Energy Conservation Program: Test Procedure for Consumer Water Heaters and Residential-Duty Commercial Water Heaters, 40406-40494 [2023-11429]
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Federal Register / Vol. 88, No. 118 / Wednesday, June 21, 2023 / Rules and Regulations
For further information on how to
review the docket, contact the
Appliance and Equipment Standards
Program staff at (202) 287–1445 or by
email: ApplianceStandardsQuestions@
ee.doe.gov.
DEPARTMENT OF ENERGY
10 CFR Parts 429, 430, and 431
[EERE–2019–BT–TP–0032]
RIN 1904–AE77
FOR FURTHER INFORMATION CONTACT:
Energy Conservation Program: Test
Procedure for Consumer Water
Heaters and Residential-Duty
Commercial Water Heaters
Office of Energy Efficiency and
Renewable Energy, Department of
Energy.
ACTION: Final rule.
AGENCY:
This final rule incorporates by
reference the latest version of the
industry testing standard for consumer
water heaters and residential-duty
commercial water heaters and adopts
relevant portions of those standards into
the Federal test procedure. In this final
rule, the U.S. Department of Energy
(DOE) is also expanding the scope of
coverage of the test procedure to apply
to certain consumer water heater
designs (including circulating water
heaters and low-temperature water
heaters), adding definitions for certain
specialty water heaters, updating test
conditions and tolerance requirements
to reduce burden, clarifying test set-up
and installation methods, addressing the
test conduct for products which can
store water at temperatures above the
delivery setpoint, establishing an
effective volume calculation, and
extending untested provisions to
electric instantaneous water heaters.
DATES: The effective date of this rule is
July 21, 2023. The final rule changes
will be mandatory for consumer water
heater testing starting December 18,
2023 and for residential-duty
commercial water heater testing starting
June 17, 2024. The incorporation by
reference of certain material listed in
this rule is approved by the Director of
the Federal Register on July 21, 2023.
ADDRESSES: The docket, which includes
Federal Register notices, public meeting
attendee lists and transcripts,
comments, and other supporting
documents/materials, is available for
review at www.regulations.gov. All
documents in the docket are listed in
the www.regulations.gov index.
However, not all documents listed in
the index may be publicly available,
such as those containing information
that is exempt from public disclosure.
A link to the docket web page can be
found at: www.regulations.gov/docket/
EERE-2019-BT-TP-0032. The docket
web page contains instructions on how
to access all documents, including
public comments, in the docket.
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SUMMARY:
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Ms. Julia Hegarty, U.S. Department of
Energy, Office of Energy Efficiency and
Renewable Energy, Building
Technologies Office, EE–5B, 1000
Independence Avenue SW, Washington,
DC 20585–0121. Telephone: (202) 597–
6737. Email: ApplianceStandards
Questions@ee.doe.gov.
Mr. Eric Stas, U.S. Department of
Energy, Office of the General Counsel,
GC–33, 1000 Independence Avenue SW,
Washington, DC 20585–0121.
Telephone: (202) 586–5827. Email:
Eric.Stas@hq.doe.gov.
SUPPLEMENTARY INFORMATION: DOE
incorporates by reference the following
industry standards into part 430:
ANSI/ASHRAE Standard 41.1–2020,
‘‘Standard Methods for Temperature
Measurement,’’ ANSI-approved June 30,
2020 (‘‘ASHRAE 41.1–2020’’).
ANSI/ASHRAE Standard 41.6–2014,
‘‘Standard Method for Humidity
Measurement,’’ ANSI-approved July 3,
2014 (‘‘ASHRAE 41.6–2014’’).
ANSI/ASHRAE Standard 118.2–2022,
‘‘Method of Testing for Rating
Residential Water Heaters and
Residential-Duty Commercial Water
Heaters,’’ ANSI-approved March 1, 2022
(‘‘ASHRAE 118.2–2022’’).
Copies of ASHRAE 41.1–2020,
ASHRAE 41.6–2014, and ASHRAE
118.2–2022 can be obtained from the
American Society of Heating,
Refrigerating, and Air-Conditioning
Engineers, Inc., (ASHRAE), 180
Technology Parkway NW, Peachtree
Corners, GA 30092, (800) 527–4723 or
(404) 636–8400, or online at:
www.ashrae.org.
ASTM D2156–09 (Reapproved 2018)
‘‘Standard Test Method for Smoke
Density in Flue Gases from Burning
Distillate Fuels,’’ approved October 1,
2018 (‘‘ASTM D2156–09 (RA 2018)’’).
ASTM E97–82 (Reapproved 1987)
‘‘Standard Test Methods for Directional
Reflectance Factor, 45-Deg 0-Deg, of
Opaque Specimens by Broad-Band
Filter Reflectometry,’’ approved October
29, 1982 and withdrawn 1991 (‘‘ASTM
E97–1987 (W1991)’’).
Copies of ASTM D2156–09 (RA 2018)
can be obtained from ASTM
International (ASTM), 100 Barr Harbor
Drive, P.O. Box C700, West
Conshohocken, PA 19428–2959 or
online at: www.astm.org.
Copies of ASTM E97–1987 (W1991)
are reasonably available from standards
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resellers including GlobalSpec’s
Engineering 360 (https://
standards.globalspec.com/std/3801495/
astm-e97-82-1987) and IHS Markit
(https://.global.ihs.com/doc_
detail.cfm?document_
name=ASTM%20E97&item_s_
key=00020483).
See section IV.N of this document for
a further discussion of these industry
standards.
Table of Contents
I. Authority and Background
A. Authority
B. Background
II. Synopsis of the Final Rule
III. Discussion
A. Scope of Applicability and Definitions
1. Demand-Response Water Heaters
2. Heat Pump Water Heaters
3. Residential-Duty Commercial Water
Heaters
4. Specialty Water Heaters
B. Updates to Industry Standards
1. ASHRAE 41.1–2020
2. ASHRAE 118.2–2022
C. Test Conditions and Tolerances
1. Supply Water Temperature
Measurements
2. Gas Pressure
3. Input Rate
4. Ambient Test Condition Tolerances
5. Electrical Supply Voltage Tolerances
6. Flow Rate Tolerances
7. Optional Test Conditions for Heat Pump
Water Heaters
D. Test Set-Up and Installation
1. Split-System Heat Pump Water Heaters
2. Mixing Valves
3. Flow Meter Location
4. Separate Storage Tanks
E. Test Conduct
1. High Temperature Testing
2. Very Small Draw Pattern Flow Rate
3. Low-Temperature Water Heaters
4. Delivery Temperature for FlowActivated Water Heaters
5. Heat Pump Water Heaters
6. Draw Pattern for Commercial
Applications
7. Method for Determining Internal Tank
Temperature for Certain Water Heaters
8. Alternate Order 24-Hour Simulated-Use
Test
F. Computations
1. Mass Calculations
2. Effective Storage Volume
G. Untested Provisions (Alternative
Efficiency Determination Methods)
1. Representations of First-Hour Ratings for
Untested Basic Models
2. Alternative Rating Method for Electric
Instantaneous Water Heaters
H. Corrections and Clarifications
1. Flow-Activated Terminology
2. Second Identical 24-Hour Simulated-Use
Test
3. Connected Products
4. Heating Value of Gas
I. Effective and Compliance Dates
J. Test Procedure Costs
1. Separate Storage Tanks
2. Method for Determining Internal Tank
Temperature for Certain Water Heaters
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3. High Temperature Testing
4. Additional Amendments
IV. Procedural Issues and Regulatory Review
A. Review Under Executive Orders 12866,
13563, and 14094
B. Review Under the Regulatory Flexibility
Act
C. Review Under the Paperwork Reduction
Act of 1995
D. Review Under the National
Environmental Policy Act of 1969
E. Review Under Executive Order 13132
F. Review Under Executive Order 12988
G. Review Under the Unfunded Mandates
Reform Act of 1995
H. Review Under the Treasury and General
Government Appropriations Act, 1999
I. Review Under Executive Order 12630
J. Review Under Treasury and General
Government Appropriations Act, 2001
K. Review Under Executive Order 13211
L. Review Under Section 32 of the Federal
Energy Administration Act of 1974
M. Congressional Notification
N. Description of Materials Incorporated by
Reference
V. Approval of the Office of the Secretary
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I. Authority and Background
Consumer water heaters are included
in the list of ‘‘covered products’’ for
which DOE is authorized to establish
and amend energy conservation
standards and test procedures. (42
U.S.C. 6292(a)(4)) DOE’s energy
conservation standards and test
procedures for consumer water heaters
are currently prescribed respectively at
title 10 of the Code of Federal
Regulations (CFR), part 430, section
32(d), and 10 CFR part 430, subpart B,
appendix E ((appendix E), Uniform Test
Method for Measuring the Energy
Consumption of Water Heaters.
Residential-duty commercial water
heaters, for which DOE is also
authorized to establish and amend
energy conservation standards and test
procedures (42 U.S.C. 6311(1)(K)), must
also be tested according to appendix E.
10 CFR 431.106(b)(1) (See 42 U.S.C.
6295(e)(5)(H)). DOE’s energy
conservation standards for residentialduty commercial water heaters are
currently prescribed at 10 CFR
431.110(b)(1). The following sections
discuss DOE’s authority to establish and
amend test procedures for consumer
water heaters and residential-duty
commercial water heaters, as well as
relevant background information
regarding DOE’s consideration of test
procedures for these products and
equipment.
A. Authority
The Energy Policy and Conservation
Act, as amended (EPCA),1 authorizes
1 All references to EPCA in this document refer
to the statute as amended through the Energy Act
of 2020, Public Law 116–260 (Dec. 27, 2020), which
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DOE to regulate the energy efficiency of
a number of consumer products and
certain industrial equipment. (42 U.S.C.
6291–6317, as codified) Title III, Part B 2
of EPCA established the Energy
Conservation Program for Consumer
Products Other Than Automobiles,
which sets forth a variety of provisions
designed to improve energy efficiency.
(42 U.S.C. 6291–6309, as codified)
These products include consumer water
heaters, one of the subjects of this
document. (42 U.S.C. 6292(a)(4)) Title
III, Part C 3 of EPCA, added by Public
Law 95–619, Title IV, section 441(a),
established the Energy Conservation
Program for Certain Industrial
Equipment, which again sets forth a
variety of provisions designed to
improve energy efficiency. (42 U.S.C.
6311–6317, as codified) This equipment
includes residential-duty commercial
water heaters, which are also the subject
of this document. (42 U.S.C. 6311(1)(K))
The energy conservation program
under EPCA consists essentially of four
parts: (1) testing, (2) labeling, (3) Federal
energy conservation standards, and (4)
certification and enforcement
procedures. Relevant provisions of
EPCA specifically include definitions
(42 U.S.C. 6291; 42 U.S.C. 6311), test
procedures (42 U.S.C. 6293; 42 U.S.C.
6314), labeling provisions (42 U.S.C.
6294; 42 U.S.C. 6315), energy
conservation standards (42 U.S.C. 6295;
42 U.S.C. 6313), and the authority to
require information and reports from
manufacturers (42 U.S.C. 6296; 42
U.S.C. 6316).
The Federal testing requirements
consist of test procedures that
manufacturers of covered products and
commercial equipment must use as the
basis for: (1) certifying to DOE that their
products/equipment comply with the
applicable energy conservation
standards adopted pursuant to EPCA (42
U.S.C. 6295(s); 42 U.S.C. 6296; 42 U.S.C.
6316(a)-(b)), and (2) making other
representations about the efficiency of
those products/equipment (42 U.S.C.
6293(c); 42 U.S.C. 6314(d)). Similarly,
DOE must use these test procedures to
determine whether the products comply
with any relevant standards
promulgated under EPCA. (42 U.S.C.
6295(s))
Federal energy efficiency
requirements for covered products and
equipment established under EPCA
generally supersede State laws and
regulations concerning energy
reflect the last statutory amendments that impact
Parts A and A–1 of EPCA.
2 For editorial reasons, upon codification in the
U.S. Code, Part B was redesignated Part A.
3 For editorial reasons, upon codification in the
U.S. Code, Part C was redesignated Part A–1.
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conservation testing, labeling, and
standards. (42 U.S.C. 6297(a)-(c); 42
U.S.C. 6316(a)-(b)) DOE may, however,
grant waivers of Federal preemption in
limited circumstances for particular
State laws or regulations, in accordance
with the procedures and other
provisions of EPCA. (42 U.S.C. 6297(d);
42 U.S.C. 6316(a); 42 U.S.C.
6316(b)(2)(D))
Under 42 U.S.C. 6293, EPCA sets forth
the criteria and procedures DOE must
follow when prescribing or amending
test procedures for covered products.
Specifically, EPCA requires that any test
procedures prescribed or amended shall
be reasonably designed to produce test
results which measure energy
efficiency, energy use, or estimated
annual operating cost of a covered
product during a representative average
use cycle or period of use and not be
unduly burdensome to conduct. (42
U.S.C. 6293(b)(3)) Under 42 U.S.C. 6314,
the statute sets forth the criteria and
procedures DOE must follow when
prescribing or amending test procedures
for covered equipment, reciting similar
requirements at 42 U.S.C. 6314(a)(2).
In addition, the Energy Independence
and Security Act of 2007 amended
EPCA to require that DOE amend its test
procedures for all covered consumer
products to integrate measures of
standby mode and off mode energy
consumption. (42 U.S.C. 6295(gg)(2)(A))
Standby mode and off mode energy
consumption must be incorporated into
the overall energy efficiency, energy
consumption, or other energy descriptor
for each covered product, unless the
current test procedure already accounts
for and incorporates the standby mode
and off mode energy consumption, or if
such integration is technically
infeasible. (42 U.S.C. 6295(gg)(2)(A)(i)–
(ii)) If an integrated test procedure is
technically infeasible, DOE must
prescribe separate standby mode and off
mode energy use test procedures for the
covered product, if a separate test is
technically feasible. (42 U.S.C.
6295(gg)(2)(A)(ii))) Any such
amendment must consider the most
current versions of the International
Electrotechnical Commission (IEC)
Standard 62301 4 and IEC Standard
62087,5 as applicable. (42 U.S.C.
6295(gg)(2)(A))
The American Energy Manufacturing
Technical Corrections Act (AEMTCA),
Public Law 112–210, further amended
4 IEC 62301, Household electrical appliances—
Measurement of standby power (Edition 2.0, 2011–
01).
5 IEC 62087, Audio, video and related
equipment—Methods of measurement for power
consumption (Edition 1.0, Parts 1–6: 2015, Part 7:
2018).
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EPCA to require that DOE establish a
uniform efficiency descriptor and
accompanying test methods to replace
the energy factor (EF) metric for covered
consumer water heaters and the thermal
efficiency (TE) and standby loss (SL)
metrics for commercial water-heating
equipment 6 within one year of the
enactment of AEMTCA. (42 U.S.C.
6295(e)(5)(B)–(C)) The uniform
efficiency descriptor and accompanying
test method were required to apply, to
the maximum extent practicable, to all
water-heating technologies in use at the
time and to future water-heating
technologies, but could exclude specific
categories of covered water heaters that
do not have residential uses, can be
clearly described, and are effectively
rated using the TE and SL descriptors.
(42 U.S.C. 6295(e)(5)(F) and (H)) In
addition, beginning one year after the
date of publication of DOE’s final rule
establishing the uniform descriptor, the
efficiency standards for covered water
heaters were required to be
denominated according to the uniform
efficiency descriptor established in the
final rule (42 U.S.C. 6295(e)(5)(D)); and
for affected covered water heaters tested
prior to the effective date of the test
procedure final rule, DOE was required
to develop a mathematical factor for
converting the measurement of their
energy efficiency from the EF, TE, and
SL metrics to the new uniform energy
descriptor. (42 U.S.C. 6295(e)(5)(E)(i)–
(ii))
EPCA also requires that, at least once
every seven years, DOE evaluate test
procedures for each type of covered
product and covered equipment,
including consumer water heaters and
residential-duty commercial water
heaters, to determine whether amended
test procedures would more accurately
or fully comply with the requirements
for the test procedures to not be unduly
burdensome to conduct and be
6 The initial thermal efficiency and standby loss
test procedures for commercial water heating
equipment (including residential-duty commercial
water heaters) were added to EPCA by the Energy
Policy Act of 1992 (EPACT 1992), Public Law 102–
486, and corresponded to those referenced in the
ASHRAE and Illuminating Engineering Society of
North America (IESNA) Standard 90.1–1989 (i.e.,
ASHRAE Standard 90.1–1989). (42 U.S.C.
6314(a)(4)(A)) DOE subsequently updated the
commercial water heating equipment test
procedures on two separate occasions—once in a
direct final rule published on October 21, 2004, and
again in a final rule published on May 16, 2012.
These rules incorporated by reference certain
sections of the latest versions of American National
Standards Institute (ANSI) Standard Z21.10.3, Gas
Water Heaters, Volume III, Storage Water Heaters
with Input Ratings Above 75,000 Btu Per Hour,
Circulating and Instantaneous, available at the time
(i.e., ANSI Z21.10.3–1998 and ANSI Z21.10.3–2011,
respectively). 69 FR 61974, 61983 (Oct. 21, 2004)
and 77 FR 28928, 28996 (May 16, 2012).
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reasonably designed to produce test
results that reflect energy efficiency,
energy use, and estimated operating
costs during a representative average
use cycle (or additionally, period of use
for consumer products). (42 U.S.C.
6293(b)(1)(A); 42 U.S.C. 6314(a)(1)(A))
If the Secretary determines, on her
own behalf or in response to a petition
by any interested person, that a test
procedure should be prescribed or
amended, the Secretary shall promptly
publish in the Federal Register
proposed test procedures and afford
interested persons an opportunity to
present oral and written data, views,
and arguments with respect to such
procedures. (42 U.S.C. 6293(b)(2); 42
US.C. 6314(b)) The comment period on
a proposed rule to amend a test
procedure shall be at least 60 days 7 and
may not exceed 270 days. (42 U.S.C.
6293(b)(2)) In prescribing or amending a
test procedure, the Secretary shall take
into account such information as the
Secretary determines relevant to such
procedure, including technological
developments relating to energy use or
energy efficiency of the type (or class)
of covered products involved. (42 U.S.C.
6293(b)(2)) If DOE determines that test
procedure revisions are not appropriate,
DOE must publish in the Federal
Register its determination not to amend
the test procedures. (42 U.S.C.
6293(b)(1)(A)(ii); 42 U.S.C.
6314(a)(1)(A)(ii)) DOE is publishing this
final rule in satisfaction of the 7-year
review requirement specified in EPCA.
(42 U.S.C. 6293(b)(1)(A) and 42 U.S.C.
6314(a)(1)(A))
B. Background
The following discussion provides a
brief history of the current rulemaking,
which considers potential amendments
to the test procedure for consumer water
heaters and residential-duty commercial
water heaters.8 On April 16, 2020, DOE
published in the Federal Register a
request for information (April 2020 RFI)
seeking comments on the existing DOE
test procedure for consumer water
heaters and residential-duty commercial
water heaters. 85 FR 21104. The April
2020 RFI discussed a draft version of the
7 For
covered equipment, if the Secretary
determines that a test procedure amendment is
warranted, the Secretary must publish proposed test
procedures in the Federal Register and afford
interested persons an opportunity (of not less than
45 days’ duration) to present oral and written data,
views, and arguments on the proposed test
procedure. (42 U.S.C. 6314(b))
8 For a more complete history of earlier
rulemaking efforts to develop the energy
conservation standards and test procedure for
consumer water heaters and residential-duty
commercial water heaters, please consult the
January 11, 2022 NOPR. See 87 FR 1554, 1556–
1558.
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American National Standards Institute
(ANSI)/American Society of Heating,
Refrigeration, and Air Conditioning
Engineers (ASHRAE) Standard 118.2,
‘‘Method of Testing for Rating
Residential Water Heaters and
Residential-Duty Commercial Water
Heaters,’’ published in March 2019
(March 2019 ASHRAE Draft 118.2),
which is very similar to the existing
DOE test procedure for consumer water
heaters and residential-duty commercial
water heaters. 85 FR 21104, 21108–
21110 (April 16, 2020).
In the April 2020 RFI, DOE requested
comments, information, and data about
a number of issues, including: (1)
differences between the March 2019
ASHRAE Draft 118.2 and the existing
DOE test procedure; (2) test tolerances
for supply water temperature, ambient
temperature, relative humidity, voltage,
and gas pressure; (3) the location of the
instrumentation that measures water
volume or mass; and (4) how to test
certain types of consumer water heaters
that cannot be easily tested to the
existing DOE test procedure (i.e.,
recirculating gas-fired instantaneous
water heaters, water heaters that cannot
deliver water at 125 degrees Fahrenheit
(°F) ±5 °F, and water heaters with
storage volumes greater than 2 gallons
that cannot have their internal tank
temperatures measured). Id. at 85 FR
21109–21114.
DOE subsequently published in the
Federal Register a notice of proposed
rulemaking on January 11, 2022
(January 2022 NOPR) in which the
Department proposed to update
appendix E, and related sections of the
CFR, as follows:
(1) Incorporate by reference current
versions of industry standards
referenced by the current and proposed
DOE test procedures: ASHRAE Standard
41.1,9 ASHRAE Standard 41.6,10 the
pending update to ASHRAE Standard
118.2 11 (contingent on it being
substantively the same as the draft
which was under review), ASTM
International (ASTM) Standard
D2156,12 and ASTM Standard E97.13
9 ASHRAE Standard 41.1–2020, ‘‘Standard
Methods for Temperature Measurement,’’ approved
June 30, 2020.
10 ASHRAE Standard 41.6–2014, ‘‘Standard
Method for Humidity Measurement,’’ ANSI
approved July 3, 2014.
11 ASHRAE Standard 118.2–2022, ‘‘Method of
Testing for Rating Residential Water Heaters and
Residential-Duty Commercial Water Heaters,’’ ANSI
approved March 1, 2022.
12 ASTM Standard D2156–09 (RA 2018),
‘‘Standard Test Method for Smoke Density in Flue
Gases from Burning Distillate Fuels,’’ reapproved
October 1, 2018.
13 ASTM Standard E97–1987 (W 1991), ‘‘Standard
Test Methods for Directional Reflectance Factor, 45-
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(2) Add definitions for ‘‘circulating
water heater,’’ ‘‘low temperature water
heater,’’ and ‘‘tabletop water heater.’’
(3) Specify how a mixing valve should
be installed when the water heater is
designed to operate with one.
(4) Modify flow rate requirements
during the first-hour rating (FHR) test
for water heaters with a rated storage
volume less than 20 gallons.
(5) Modify timing of the first
measurement in each draw of the 24hour simulated-use test.
(6) Clarify the determination of the
first recovery period.
(7) Clarify the mass of water to be
used to calculate recovery efficiency.
(8) Modify the terminology
throughout appendix E to explicitly
state ‘‘non-flow activated’’ and ‘‘flowactivated’’ water heater, where
appropriate.
(9) Clarify the descriptions of defined
measured values for the standby period
measurements.
(10) Modify the test condition
specifications and tolerances, including
electric supply voltage tolerance,
ambient temperature, ambient dry-bulb
temperature, ambient relative humidity,
standard temperature and pressure
definition, gas supply pressure, and
manifold pressure.
(11) Add provisions to address gasfired water heaters with measured fuel
input rates that deviate from the
certified input rate.
(12) Clarify provisions for calculating
the volume or mass delivered.
(13) Add specifications for testing for
the newly defined ‘‘low temperature
water heaters.’’
(14) Clarify testing requirements for
the heat pump part of a split-system
heat pump water heater.
(15) Define the use of a separate
unfired hot water storage tank for testing
water heaters designed to operate with
a separately sold hot water storage tank.
(16) Clarify that any connection to an
external network or control be
disconnected during testing.
(17) Add procedures for estimating
internal stored water temperature for
water heater designs in which the
internal tank temperature cannot be
directly measured.
(18) Modify the provisions for
untested water heater basic models
within 10 CFR 429.70(g) to include
electric instantaneous water heaters.
87 FR 1554, 1558.14
DOE held a public meeting related to
the January 2022 NOPR on January 27,
2022 (hereinafter, the NOPR public
meeting).
On July 14, 2022, DOE published a
supplemental notice of proposed
rulemaking in the Federal Register (July
2022 SNOPR), that proposed to
maintain the proposals from the January
2022 NOPR but with modifications
discussed in the July 2022 SNOPR. 87
FR 42270. Specifically, the July 2022
SNOPR proposed to further update
appendix E and related sections of the
CFR by:
(1) Additionally requiring that, for
water heaters with rated storage volume
less than 2 gallons and a rated
maximum gallons per minute (Max
GPM or maximum GPM) of less than 1
gallon per minute, the flow rate
tolerance shall be ±25 percent of the
rated Max GPM.
(2) Allowing optional efficiency
representations at alternative test
conditions for heat pump water heaters.
(3) Adding a definition for ‘‘splitsystem heat pump water heaters’’ to
distinguish these from circulating heat
pump water heaters (i.e., ‘‘heat pumponly’’ water heaters).
(4) Requiring gas-fired circulating
water heaters to be tested using an
unfired hot water storage tank
(UFHWST) with a storage volume
between 80 and 120 gallons and meets
but does not exceed the minimum
energy conservation standards (based on
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R-value) required at 10 CFR 431.110(a),
and that circulating heat pump water
heaters be tested using a 40-gallon
electric resistance water heater at the
minimum UEF standard required at 10
CFR 430.32(d).
(5) Requiring that water heaters (with
the exception of demand-response water
heaters) with user-selectable modes to
‘‘overheat’’ the water stored in the tank
to increase effective capacity be tested at
the highest internal tank temperature
that can be achieved while maintaining
the outlet water temperature at 125 °F
±5 °F. (If no such overheated mode
exists, the unit is to be tested in a
default mode.)
(6) Defining ‘‘demand-response water
heater’’ based on the U.S.
Environmental Protection Agency (EPA)
ENERGY STAR Product Specification
for Residential Water Heaters Version
5.0 (ENERGY STAR Water Heaters
Specification v5.0) 15 definition for
‘‘connected water heating product,’’
with the additional requirement that
demand-response water heaters cannot
overheat as a result of user-initiated
operation.
(7) Establishing a metric and method
for determining the effective storage
volume.
(8) Adopting a method of determining
the internal storage tank temperature for
certain water heaters which cannot be
directly measured using draws at the
beginning and end of the 24-hour
simulated-use test. 87 FR 42270, 42273–
42274 (July 14, 2022).
This final rule responds to comments
received in response to the January 2022
NOPR that were not addressed in the
July 2022 SNOPR and comments
received in response to the July 2022
SNOPR. Table I.1 presents the list of
commenters who provided written
submissions and/or oral statements at
the NOPR public meeting which are
addressed in this final rule.
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TABLE I.1—LIST OF COMMENTERS WITH WRITTEN SUBMISSIONS ADDRESSED IN THIS FINAL RULE
Commenter(s)
Reference in this final rule
Comment No. in the docket
A.O. Smith Corporation ................................................................
A.O. Smith ................................
Air Conditioning, Heating, and Refrigeration Institute ..................
AHRI .........................................
American Public Gas Association ................................................
Appliance Standards Awareness Project .....................................
APGA .......................................
ASAP ........................................
NOPR No. 37; Transcript*;
SNOPR No. 51*.
NOPR No. 40; Transcript;
SNOPR No. 55.
NOPR No. 38 ...........................
Transcript .................................
Appliance Standards Awareness Project, American Council for
an Energy-Efficient Economy, National Consumer Law Center
(on behalf of its low-income clients).
ASAP, ACEEE, and NCLC ......
NOPR No. 34 ...........................
Deg 0-Deg, of Opaque Specimens by Broad-Band
Filter Reflectometry,’’ approved January 1987,
withdrawn 1991. Referenced by ASTM Standard
D2156–09 (RA 2018).
14 A correction was published in the Federal
Register on January 19, 2022, to properly reflect the
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date of the public meeting to discuss the January
2022 NOPR. 87 FR 2731.
15 EPA published the ENERGY STAR Water
Heater Specification v5.0 on July 18, 2022. The
ENERGY STAR Water Heater Specification v5.0 is
available online at: www.energystar.gov/products/
PO 00000
Frm 00005
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Commenter type
Manufacturer.
Manufacturer Trade Association.
Utility Trade Association.
Efficiency Advocacy Organization.
Efficiency Advocacy Organizations.
spec/residential_water_heaters_specification_
version_5_0_pd (Last accessed on July 25, 2022).
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Federal Register / Vol. 88, No. 118 / Wednesday, June 21, 2023 / Rules and Regulations
TABLE I.1—LIST OF COMMENTERS WITH WRITTEN SUBMISSIONS ADDRESSED IN THIS FINAL RULE—Continued
Commenter(s)
Reference in this final rule
Comment No. in the docket
Commenter type
Appliance Standards Awareness Project, American Council for
an Energy-Efficient Economy, Natural Resources Defense
Council.
Applied Energy Technology Company .........................................
Bradford White Corporation ..........................................................
Edison Electric Institute ................................................................
GE Appliances ..............................................................................
Jim Lutz ........................................................................................
Nathan Dyson ...............................................................................
New York State Energy Research and Development Authority ..
Northwest Energy Efficiency Alliance ...........................................
ASAP, ACEEE, and NRDC ......
SNOPR No. 54 .........................
Efficiency Advocacy Organizations.
AET ..........................................
BWC .........................................
EEI ............................................
GEA ..........................................
Lutz ...........................................
Dyson .......................................
NYSERDA ................................
NEEA ........................................
NOPR No. 29 ...........................
NOPR No. 33; SNOPR No. 48
Transcript .................................
SNOPR No. 53 .........................
NOPR No. 35 ...........................
NOPR No. 28 ...........................
NOPR No. 32; SNOPR No. 50
NOPR No. 30; SNOPR No. 56
Nyle Water Heating Systems, LLC ..............................................
Pacific Gas and Electric Company, San Diego Gas and Electric,
and Southern California Edison, collectively referred to as the
‘‘California Investor-Owned Utilities’’.
Rheem Manufacturing Company ..................................................
Nyle ..........................................
CA IOUs ...................................
SNOPR No. 57 .........................
NOPR No. 36; SNOPR No. 52
Testing Laboratory.
Manufacturer.
Utility Trade Association.
Manufacturer.
Individual.
Individual.
State Agency.
Efficiency Advocacy Organization.
Manufacturer.
Utilities.
Rheem ......................................
SEA Groups, Ltd ..........................................................................
Stone Mountain Technologies, Inc ...............................................
SEA ..........................................
SMTI .........................................
NOPR No. 31; Transcript;
SNOPR No. 47.
NOPR No. 24 ...........................
SNOPR No. 49 .........................
Manufacturer.
Manufacturer.
Manufacturer.
* Note: The January 27, 2022 TP NOPR Pubic Meeting Transcript can be found in the docket for this rulemaking at www.regulations.gov under entry number
EERE–2019–BT–TP–0032–0027. Comments arising from the public meeting will be cited as follows: (Commenter name, Jan. 27, 2022 Public Meeting Transcript, No.
27 at p. X).
A parenthetical reference at the end of
a comment quotation or paraphrase
provides the location of the item in the
public record.16 To the extent that
interested parties have provided written
comments that are substantively similar
to any oral comments provided during
the NOPR public meeting, DOE cites the
written comments throughout this final
rule. Any oral comments provided
during the webinar that are
substantively distinct from a submitter’s
written comments are summarized and
cited separately throughout this final
rule.
APGA commented that DOE should
adopt changes to its rulemaking process
as outlined in a report by National
Academies of Sciences, Engineering,
and Medicine (NASEM) for both test
procedures and standards. (APGA, No.
38 at p. 2) In response, the Department
notes that the rulemaking process for
test procedures of covered products and
equipment are outlined at appendix A
to subpart C of 10 CFR part 430, and
DOE periodically examines and revises
these provisions in separate rulemaking
proceedings.
Section II of this document provides
a synopsis of this final rule, and section
III of this document discusses each
amendment to the test procedure for
consumer water heaters and residentialduty commercial water heaters in detail.
II. Synopsis of the Final Rule
In this final rule, DOE amends
appendix E and related sections of the
CFR. In summary, the final rule:
1. Incorporates by reference current
versions of industry standards: ASHRAE
41.1, ASHRAE 41.6, ASHRAE 118.2,
ASTM D2156, and ASTM E97.
2. Adds definitions for ‘‘circulating
water heater, ‘‘tabletop water heater,
and ‘‘low-temperature water heater.
3. Harmonizes various aspects of the
DOE test procedure with industry test
procedures ASHRAE 118.2–2022 and
NEEA Advanced Water Heating
Specification v8.0.
4. Modifies the test condition
specifications and tolerances, including
electric supply voltage tolerance,
ambient conditions (ambient dry-bulb
temperature and ambient relative
humidity), standard temperature and
pressure definition, gas supply pressure,
manifold pressure, inlet water
temperature, and flow rate tolerances,
and adds optional test conditions for
heat pump water heaters.
5. Specifies and clarifies methods for
mixing valve installation for affected
water heaters, orifice modification, and
calculation of volume or mass delivered.
6. Defines the use of a separate
unfired hot water storage tank or
separate electric storage water heater for
testing water heaters designed to operate
with a separately sold tank.
7. Adds procedures for estimating
internal stored water temperature for
water heater designs in which the
internal tank temperature cannot be
directly measured.
8. Clarifies test procedures for water
heaters with network connection
capabilities.
9. Clarifies test procedures for flowactivated water heaters and water
heaters that are not flow-activated by
aligning terminology.
10. Includes additional testing
provisions for electric resistance water
heaters undergoing optional high
temperature testing.
11. Includes a calculation for
determining the effective storage
volume of a water heater.
The adopted amendments are
summarized in Table II.1 compared to
the test procedure provision prior to the
amendment, as well as the reason for
the adopted change.
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TABLE II.1—SUMMARY OF CHANGES IN THE AMENDED TEST PROCEDURE
DOE test procedure prior to amendment
Amended test procedure
References the 1986 (Reaffirmed 2006) version of ASHRAE
41.1 for methods for temperature measurement.
The 1982 version of ASHRAE 41.6 for methods for humidity
measurement is referenced within the 1986 version of
ASHRAE 41.1.
References the updated 2020 version of ASHRAE 41.1 .......
Industry TP Update to ASHRAE 41.1.
References the 2014 version of ASHRAE 41.6, which is referenced by ASHRAE 41.1–2020.
Industry TP Update to ASHRAE 41.6.
16 The parenthetical reference provides a
reference for information located in the docket of
DOE’s rulemaking to develop test procedures for
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consumer water heaters and residential-duty
commercial water heaters. (Docket No. EERE–2019–
BT–TP–0032, which is maintained at
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Attribution
www.regulations.gov). The references are arranged
as follows: (commenter name, comment docket ID
number, page of that document).
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TABLE II.1—SUMMARY OF CHANGES IN THE AMENDED TEST PROCEDURE—Continued
DOE test procedure prior to amendment
Amended test procedure
References the 2009 version of ASTM D2156 for testing
smoke density in flue gases from burning distillate fuels.
The 1987 version of ASTM E97 for testing directional reflectance factor, 45-deg 0-deg, of opaque specimens by
broad-band filter reflectometry is referenced within ASTM
D2156–09.
Does not define a ‘‘circulating water heater’’ as used in 10
CFR 430.2.
Does not define a ‘‘tabletop water heater’’ as used as a
product class distinction at 10 CFR 430.32(d).
Interprets the upper limit for consumer electric heat pump
water heaters to be 12 kW of input, with ‘‘commercial heat
pump water heater’’ defined at 10 CFR 431.102 as having
rated electric power input greater than 12 kW.
Does not address how to configure a water heater for test
when a mixing valve is required for proper operation.
Requires the flow rate during the FHR test to be 1.0 ± 0.25
gpm (3.8 ± 0.95 L/min) for water heaters with a rated storage volume less than 20 gallons.
Does not address the situation in which the first recovery
ends during a draw when testing to the 24-hour simulateduse test.
References the version of ASTM D2156 that was reaffirmed
in 2018.
References the 1987 version of ASTM E97, which is referenced by ASTM D2156–09 (RA 2018).
Industry TP Update to ASTM D2156.
Adds a definition for ‘‘circulating water heater’’ to 10 CFR
430.2.
Adds a definition for ‘‘tabletop water heater’’ to 10 CFR
430.2.
Corrects the upper limit for consumer electric heat pump
water heaters to 24 amperes at 250 volts of input and
amends the definition for ‘‘commercial heat pump water
heater’’ accordingly.
Specifies how a mixing valve should be installed when the
water heater is designed to operate with one.
Requires the flow rate during the FHR test to be 1.5 ± 0.25
gpm (5.7 ± 0.95 L/min) for water heaters with a rated
storage volume less than 20 gallons.
Clarifies that the first recovery period will extend to the end
of the draw in which the first recovery ended, and that if a
second recovery initiates prior to the end of the draw, that
the second recovery is part of the first recovery period as
well.
Clarifies that, for the calculation of recovery efficiency, the
mass of water removed during the first recovery period includes water removed during all draws from the start of
the test until the end of the first recovery period.
Clarifies the alternate approach to determine the energy
consumed during the 24-hour simulated use test if a
standby period occurs after the final draw of the test.
Allow for testing certain consumer water
heaters.
Reinstate definition inadvertently removed by previous final rule.
Make consistent with statutory definition.
The recovery efficiency equation for storage-type water
heaters refers to the mass of water removed from the
start of the test to the end of the first recovery period.
The procedures for the standby period after the last draw of
the 24-hour simulated-use test allow for a recovery to
occur at the end of the 8-hour standby period, which indicates that the power to the main burner, heating element,
or compressor is not disabled.
Appendix E uses the phrases ‘‘storage-type’’ and ‘‘instantaneous-type’’ to refer to ‘‘non-flow activated’’ and ‘‘flow-activated’’ water heaters, respectively.
The descriptions for Qsu,0, Qsu,f, Tsu,0, Tsu,f, tstby,1, Tt,stby,1,
and Ta,stby,1 only address when the standby period occurs
between draw clusters 1 and 2.
Specifies that the first required measurement for each draw
of the 24-hour simulated-use test is 5 seconds after the
draw is initiated.
Requires the electric supply voltage to be within ±1 percent
of the rated voltage for the entire test.
Requires maintaining ambient temperature for non-heat
pump water heaters within a range of 67.5 °F ± 2.5 °F.
Requires maintaining the dry-bulb temperature for heat
pump water heaters within a range of 67.5 °F ± 1 °F.
Requires maintaining the relative humidity for heat pump
water heaters within a range of 50 percent ±2 percent.
Requires that the heating value be corrected to a standard
temperature and pressure, but does not state what temperature and pressure is standard or how to correct the
heating value to the standard temperature and pressure.
lotter on DSK11XQN23PROD with RULES2
Requires that the manifold pressure be within ±10 percent of
the manufacturer recommended value.
Does not specify the input rate at which the gas supply
pressure tolerance is determined.
Does not contain procedures for modifying the orifice of a
water heater that is not operating at the manufacturer
specified input rate.
Does not specify how to calculate the mass removed from
the water heater when mass is calculated indirectly using
density and volume measurements.
Does not accommodate testing of ‘‘low-temperature water
heaters’’ in appendix E.
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Attribution
Industry TP Update to ASTM E97.
Method added by DOE to improve repeatability.
Harmonization with industry TP
ASHRAE 118.2–2022.
Harmonization with industry TP
ASHRAE 118.2–2022.
Harmonization with industry TP
ASHRAE 118.2–2022.
Harmonization with industry TP
ASHRAE 118.2–2022.
Uses the terms ‘‘non-flow activated’’ and ‘‘flow-activated’’
water heater, where appropriate.
Clarification.
The descriptions for Qsu,0, Qsu,f, Tsu,0, Tsu,f, tstby,1, Tt,stby,1,
and Ta,stby,1 are generalized to refer to the section where
the standby period is determined.
Specifies that the first required measurement for each draw
of the 24-hour simulated-use test is 15 seconds after the
draw is initiated.
Requires the electric supply voltage to be within ±2 percent
of the rated voltage beginning 5 seconds after the start of
a recovery and ending 5 seconds before the end of a recovery.
Requires maintaining the ambient temperature for non-heat
pump water heaters within a range of 67.5 °F ± 5 °F, and
with an average of 67.5 °F ± 2.5 °F.
Requires maintaining the dry-bulb temperature for heat
pump water heaters within a range of 67.5 °F ± 5 °F, and
with an average of 67.5 °F ± 1 °F during recoveries and
an average of 67.5 °F ± 2.5 °F when not recovering.
Requires maintaining the relative humidity for heat pump
water heaters within a range of 50 percent ±5 percent,
and at an average of 50 percent ±2 percent during recoveries.
States that the standard temperature is 60 °F (15.6 °C) and
the standard pressure is 30 inches of mercury column
(101.6 kPa). Provides a method for converting heating
value from the measured to the standard conditions via
incorporation by reference of ASHRAE 118.2–2022.
Clarifies that the manifold pressure tolerance applies only to
water heaters with a pressure regulator that can be adjusted. Requires that the manifold pressure be within the
greater of ±10 percent of the manufacturer recommended
value or ±0.2 inches water column.
Specifies that the gas supply pressure tolerance is to be
maintained when operating at the maximum input rate.
Adds provisions regarding the modification of the orifice ......
Clarification.
Method updated by DOE to reduce burden.
Method updated by DOE to reduce burden.
Method updated by DOE to reduce burden.
Method updated by DOE to reduce burden.
Method updated by DOE to reduce burden
Harmonization with industry TP
ASHRAE 118.2–2022.
Method updated by DOE to reduce burden.
Method added by DOE to clarify enforcement test procedure.
Method added by DOE to clarify enforcement test procedure.
Specifies how to calculate the mass of water indirectly using
density and volume measurements.
Method added by DOE to improve repeatability.
Adds a definition of ‘‘low-temperature water heater’’ in 10
CFR 430.2 and requires low temperature water heaters to
be tested to their maximum possible delivery temperature
in appendix E.
Allow for testing certain consumer water
heaters.
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TABLE II.1—SUMMARY OF CHANGES IN THE AMENDED TEST PROCEDURE—Continued
DOE test procedure prior to amendment
Amended test procedure
Attribution
Explicitly states that the heat pump part of a split-system
heat pump water heater is tested at the dry-bulb temperature and relative humidity conditions required for heat
pump water heaters, and that the storage tank is tested
at the ambient temperature and relative humidity conditions required for non-heat pump water heaters.
Requires that gas-fired circulating water heaters be tested
using a UFHWST with a storage volume between 80 and
120 gallons and that meets but does not exceed the minimum energy conservation standards required according
to 10 CFR 431.110(a), and that heat pump circulating
water heaters be tested using a 40-gallon electric storage
water heater at the minimum UEF standard required at 10
CFR 430.32(d).
Explicitly states that any connection to an external network
or control be disconnected during testing.
Establishes a method of determining the internal storage
tank temperature using draws at the beginning and end of
the 24-hour simulated use test.
Extends the untested provisions within 10 CFR 429.70(g) to
include electric instantaneous water heaters.
Method added by DOE to improve representativeness and repeatability.
Method added by DOE to improve repeatability and reproducibility.
Does not include optional efficiency representations at alternative test conditions for heat pump water heaters.
Specifies that flow rates for all water heaters with rated storage volume less than 2 gallons must be maintained within
a tolerance of ±0.25 gallons per minute. Additionally proposes that for water heaters with rated storage volume
less than 2 gallons and a rated Max GPM of less than 1
gallon per minute, the flow rate tolerance shall be ±25
percent of the rated Max GPM.
Allows for optional efficiency representations at alternative
test conditions for heat pump water heaters.
Does not include a definition for ‘‘split-system heat pump
water heater.’’.
Adds a definition for ‘‘split-system heat pump water heater’’
to distinguish these from heat pump-only water heaters.
Specifies that water heaters with multiple modes of operation be tested in the ‘‘default’’ or other similarly named
mode.
Provides a test method for electric resistance water heaters
subject to high temperature testing (setting the water
heater to the highest storage tank temperature and using
a mixing valve to temper the delivery water to be within
125 ± 5 °F). Does not require the use of this type of testing for any water heaters, however, until compliance with
amended standards is required.
Establishes a metric and method for determining the effective storage volume of storage-type water heaters and circulating water heaters.
Adopts a definition for ‘‘thermal break’’ but does not mandate the use of this component in test set-up.
Does not explicitly define the test conditions required for
each part of a split-system heat pump water heater.
Does not accommodate testing of water heaters that require
a separately-sold hot water storage tank to properly operate.
Does not address water heaters with network connection capabilities.
Does not accommodate certain water heaters for which the
mean tank temperature cannot be directly measured.
10 CFR 429.70(g) does not allow untested electric instantaneous water heaters to be certified, but does allow untested electric storage water heaters to be certified.
Does not specify flow rate tolerance for water heaters with
rated storage volume less than 2 gallons.
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Does not include any method to determine effective storage
volume of storage-type water heaters or circulating water
heaters.
Does not include a definition for ‘‘thermal break.’’ ..................
DOE has determined that the
amendments described in section III and
adopted in this document will not alter
the measured efficiency of consumer
water heaters and residential-duty
commercial water heaters, or require
retesting or recertification solely as a
result of DOE’s adoption of the
amendments to the test procedures.
Discussion of DOE’s actions are
addressed in detail in section III of this
document.
The effective date for the amended
test procedures adopted in this final
rule is 30 days after publication of this
document in the Federal Register.
Representations of energy use or energy
efficiency must be based on testing in
accordance with the amended test
procedures beginning 180 days after the
publication of this final rule for
consumer water heaters and 360 after
the publication of this final rule for
residential-duty commercial water
heaters.
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III. Discussion
A. Scope of Applicability and
Definitions
This document covers those products
that meet the definition of consumer
‘‘water heaters,’’ as defined in the
statute at 42 U.S.C. 6291(27), as codified
at 10 CFR 430.2. This document also
covers commercial water heating
equipment with residential applications
((i.e., those water heaters which meet
the definition of ‘‘residential-duty
commercial water heater’’ at 10 CFR
431.102).
In the context of covered consumer
products, EPCA defines ‘‘water heater’’
as a product which utilizes oil, gas, or
electricity to heat potable water for use
outside the heater upon demand,
including—
(a) Storage type units which heat and
store water at a thermostatically
controlled temperature, including gas
storage water heaters with an input of
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Allow for testing certain consumer water
heaters.
Clarification.
Allow for testing certain consumer water
heaters.
AEDM allowed by DOE to reduce burden.
Harmonization with industry TP NEEA
Advanced Water Heating Specification v8.0.
Harmonization with industry TP NEEA
Advanced Water Heating Specification v8.0.
Method added by DOE to improve representativeness.
Method added by DOE which adopts a
metric for additional consumer information.
Harmonization with industry TP
ASHRAE 118.2–2022.
75,000 Btu per hour or less, oil storage
water heaters with an input of 105,000
Btu per hour or less, and electric storage
water heaters with an input of 12
kilowatts or less;
(b) Instantaneous type units which
heat water but contain no more than one
gallon of water per 4,000 Btu per hour
of input, including gas instantaneous
water heaters with an input of 200,000
Btu per hour or less, oil instantaneous
water heaters with an input of 210,000
Btu per hour or less, and electric
instantaneous water heaters with an
input of 12 kilowatts or less; and
(c) Heat pump type units, with a
maximum current rating of 24 amperes
at a voltage no greater than 250 volts,
which are products designed to transfer
thermal energy from one temperature
level to a higher temperature level for
the purpose of heating water, including
all ancillary equipment such as fans,
storage tanks, pumps, or controls
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necessary for the device to perform its
function.
(42 U.S.C. 6291(27); 10 CFR 430.2)
In addition, at 10 CFR 430.2, DOE
defines several specific categories of
consumer water heaters, as follows:
(1) ‘‘Electric instantaneous water
heater’’ means a water heater that uses
electricity as the energy source, has a
nameplate input rating of 12 kW or less,
and contains no more than one gallon of
water per 4,000 Btu per hour of input.
(2) ‘‘Electric storage water heater’’
means a water heater that uses
electricity as the energy source, has a
nameplate input rating of 12 kW or less,
and contains more than one gallon of
water per 4,000 Btu per hour of input.
(3) ‘‘Gas-fired instantaneous water
heater’’ means a water heater that uses
gas as the main energy source, has a
nameplate input rating less than
200,000 Btu/h, and contains no more
than one gallon of water per 4,000 Btu
per hour of input.
(4) ‘‘Gas-fired storage water heater’’
means a water heater that uses gas as the
main energy source, has a nameplate
input rating of 75,000 Btu/h or less, and
contains more than one gallon of water
per 4,000 Btu per hour of input.
(5) ‘‘Grid-enabled water heater’’
means an electric resistance water
heater that—
(a) Has a rated storage tank volume of
more than 75 gallons;
(b) Is manufactured on or after April
16, 2015;
(c) Is equipped at the point of
manufacture with an activation lock
and;
(d) Bears a permanent label applied
by the manufacturer that—
(i) Is made of material not adversely
affected by water;
(ii) Is attached by means of non-watersoluble adhesive; and
(iii) Advises purchasers and end-users
of the intended and appropriate use of
the product with the following notice
printed in 16.5 point Arial Narrow Bold
font: ‘‘IMPORTANT INFORMATION:
This water heater is intended only for
use as part of an electric thermal storage
or demand response program. It will not
provide adequate hot water unless
enrolled in such a program and
activated by your utility company or
another program operator. Confirm the
availability of a program in your local
area before purchasing or installing this
product.’’
(6) ‘‘Oil-fired instantaneous water
heater’’ means a water heater that uses
oil as the main energy source, has a
nameplate input rating of 210,000 Btu/
h or less, and contains no more than one
gallon of water per 4,000 Btu per hour
of input.
(7) ‘‘Oil-fired storage water heater’’
means a water heater that uses oil as the
main energy source, has a nameplate
input rating of 105,000 Btu/h or less,
and contains more than one gallon of
water per 4,000 Btu per hour of input.
The definition for ‘‘grid-enabled water
heater’’ includes the term ‘‘activation
lock,’’ which is defined to mean a
control mechanism (either by a physical
device directly on the water heater or a
control system integrated into the water
heater) that is locked by default and
contains a physical, software, or digital
communication that must be activated
with an activation key to enable the
product to operate at its designed
Water heater type
specifications and capabilities and
without which the activation of the
product will provide not greater than 50
percent of the rated first-hour delivery
of hot water certified by the
manufacturer. 10 CFR 430.2. As
specified in this definition, the control
mechanism must be physically
incorporated into the water heater or, if
a control system, integrated into the
water heater to qualify as an activation
lock. DOE is aware of certain State
programs that encourage water heaters
to be equipped with communication
ports that allow for demand-response
communication between the water
heater and the utility.17 DOE notes that
presence of such a communication port,
in and of itself, would not qualify as an
activation lock for the purpose of
classifying a water heater as a gridenabled water heater. Demand-response
water heaters are discussed separately
in section III.A.1 of this final rule.
Additionally, as discussed further in
section III.A.3 of this document, the
appendix E test procedure also applies
to residential-duty commercial water
heaters. (See 10 CFR 431.106(b)(1)) DOE
defines these equipment categories at 10
CFR 431.102 as any gas-fired storage,
oil-fired storage, or electric
instantaneous commercial water heater
that meets the following conditions:
(1) For models requiring electricity,
uses single-phase external power
supply;
(2) Is not designed to provide outlet
hot water at temperatures greater than
180 °F; and
(3) Does not meet any of the following
criteria:
Indicator of non-residential application
Gas-fired Storage .....................................................................
Oil-fired Storage .......................................................................
Electric Instantaneous ..............................................................
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Rated input >105 kBtu/h; Rated storage volume >120 gallons.
Rated input >140 kBtu/h; Rated storage volume >120 gallons.
Rated input >58.6 kW; Rated storage volume >2 gallons.
In the January 2022 NOPR, DOE
discussed definitions and the scope of
appendix E for heat pump water heaters
(electric as well as gas-fired), gas-fired
instantaneous water heaters (specifically
circulating gas-fired water heaters),
tabletop water heaters, and residentialduty commercial water heaters. 87 FR
1554, 1560–1567 (Jan. 11, 2022).
Additionally, DOE proposed a new
definition for ‘‘demand-response water
heater’’ in the July 2022 SNOPR. 87 FR
42270, 42280 (July 14, 2022).
BWC generally agreed with DOE’s
determinations regarding product and
equipment definitions and
classifications. (BWC, No. 33 at p. 1)
AET generally commented that DOE’s
test procedures should be appropriate
for all consumer water heaters within
the scope of standards, especially for
electric instantaneous water heaters.
(AET, No. 29 at pp. 11–12)
17 On May 7, 2019, the State of Washington
signed House Bill 1444 which amended the Revised
Code of Washington (RCW) (i.e., the statutory code
in the State of Washington), Title 19, Chapter
19.260 (RCW 19.260). On January 6, 2020, the State
of Washington amended the Washington
Administrative Code (WAC) (i.e., the regulatory
code in the State of Washington), Title 194, Chapter
194–24 (WAC 194–24) (Washington January 2020
Amendment) to align with RCW 19.260. Similarly,
the State of Oregon published a final rule (Oregon
August 2020 final rule) on August 8, 2020, which
amended the Oregon Administrative Rules (OAR),
Chapter 330, Division 92 (OAR–330–092). The
Washington House Bill 1444 and the Oregon August
2020 final rule established a definition for electric
storage water heater (RCW 19.260.020(14); OAR–
330–092–0010(10)), an effective date of January 1,
2021 in Washington and January 1, 2022 in Oregon
(RCW 19.260.080(1); OAR–330–092–0015(17)), a
requirement that electric storage water heaters must
have a modular demand response communications
port compliant with the March 2018 version of the
ANSI/CTA–2045–A communication interface
standard, or a standard determined to be equivalent
(RCW 19.260.080(1)(a)–(b); OAR–330–092–
0020(17)), and, in Oregon, must bear a label or
marking on the products stating either ‘‘DR-ready:
CTA–2045–A’’ or ‘‘DR-ready: CTA–2045–A and
[equivalent DR system protocol]’’ (OAR–330–092–
0045(17)).
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As discussed throughout this
rulemaking, it is DOE’s intention to
ensure that the appendix E test
procedure amended by this final rule is
appropriate and applicable to all
consumer water heaters and residentialduty commercial water heaters. Sections
III.A.1 through III.A.4 of this document
address specific issues related to scope
and definitions that either DOE
requested comment on in the January
2022 NOPR or July 2022 SNOPR, or that
were identified by commenters in
response to those documents.
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1. Demand-Response Water Heaters
Storage-type water heaters that have
‘‘connected’’ capability, often referred to
as ‘‘demand-response’’ water heaters,
can be remotely activated and/or
deactivated by signals from a utility
company or another program operator,
and are able to serve as a thermal energy
storage device. DOE considered whether
specific testing requirements would be
appropriate for demand-response water
heaters (such as requiring measurement
of the energy consumed by connected
features, or providing a method for
calculating the amount of thermal
energy storage available); however, DOE
had tentatively determined that
additional test procedure provisions
(such as the calculation of a thermal
energy storage metric) are premature
and unnecessary to specify at this time
as the market continues to develop and
evolve. DOE proposed only that a
provision be added to the test procedure
to require that if a water heater can
connect to an external network or
controller, that communication shall be
disabled during testing. 87 FR 1554,
1585–1586 (Jan. 11, 2022). Several
stakeholders provided input on this
tentative determination.
NEEA encouraged DOE to adopt
definitions and test methods for
‘‘connectable’’ water heaters in the test
procedure. The commenter pointed to
the following existing and emerging
standards as references: Consumer
Technology Association (CTA) Standard
2045 (ANSI/CTA–2045)/EcoPort,18 U.S.
Environmental Protection Agency (EPA)
ENERGY STAR connected device
requirements, and AHRI 1430, Standard
for Demand Response for Electric Water
Heaters.19 NEEA stated that definitions
18 Available online at: shop.cta.tech/products/
https-cdn-cta-tech-cta-media-media-ansi-cta-2045b-final-2022-pdf (Last accessed on Sept. 17, 2022).
19 AHRI Standard 1430, ‘‘Standard for Demand
Response for Electric Water Heaters,’’ was
published in December 2022. It is an industry
consensus standard developed by an AHRI
Consensus Standards Project Committee that
includes definitions, test requirements, operating
and physical requirements, minimum data
requirements for published ratings, marking and
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of connectivity have already been
adopted by the States of Washington,
Oregon, and California as part of their
water heating appliance standards.
(NEEA, No. 30 at pp. 2–3) The CA IOUs
recommended the adoption of a
definition for the communication
capability for grid-enabled water heaters
that is consistent with the Connected
Product Criteria in the ENERGY STAR
Product Specification for Residential
Water Heaters.20 The CA IOUs also
recommended that DOE incorporate the
associated ENERGY STAR connected
products test procedure into the
appendix E test procedure. (CA IOUs,
No. 36 at pp. 2–3)
In response, DOE considered these
comments and also assessed the
operation of demand-response water
heaters as grid thermal energy storage
devices using specific communication
protocols in order to determine how to
distinguish these products from other
water heaters capable of storage tank
overheating. On July 18, 2022, EPA
published an ENERGY STAR Version
5.0 Residential Water Heater
Specification, which included
definitions for ‘‘connected water heater
product’’ and ‘‘demand response.’’
These definitions included references to
Consumer Technology Association
(CTA) Standard 2045 (ANSI/CTA–
2045),21 a design standard for a
communications module that allows a
water heater to receive signals from a
utility company (e.g., a curtailment
request). As indicated by NEEA and the
CA IOUs, the presence of a CTA–2045
port uniquely enables a water heater to
be able to participate in any demandresponse program, and DOE has
additionally determined that products
nameplate, and data and conformance conditions
for demand-response electric water heaters. For
more information, see www.ahrinet.org/searchstandards/ahri-1430-demand-flexible-electricstorage-water-heaters (Last accessed on Feb. 17,
2023).
20 According to version 5.0 of the ENERGY STAR
Program Requirements for Residential Water
Heaters Eligibility Criteria, a ‘‘connected water
heater product (CWHP)’’ includes the ENERGY
STAR certified water heater, integrated or separate
communications hardware, and additional
hardware and software required to enable
connected functionality. ‘‘Demand Response’’ is
also defined by that source to mean changes in
electric or gas usage by end-use customers from
their normal consumption patterns in response to
changes in the price of electricity or gas over time,
or to incentive payments designed to induce lower
electricity or gas use at times of high wholesale
market prices or when system reliability is
jeopardized. Version 5.0 of the ENERGY STAR
specification is available online at:
www.energystar.gov/products/spec/residential_
water_heaters_specification_version_5_0_pd (Last
accessed on July 25, 2022).
21 See section 4.D.a of the ENERGY STAR Version
5.0 specification.
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with these features are increasing in
number.
In the July 2022 SNOPR, DOE noted
that certain new water heaters were
available on the market that are shipped
from the point of manufacture with a
mixing valve installed and intentionally
‘‘overheat’’ 22 the water to a stored
temperature that is higher than the
delivery temperature setpoint to provide
additional capacity.23 87 FR 42270,
42279–42280 (July 14, 2022). DOE
proposed specific test requirements for
such products (see section III.E.1 of this
document for discussion). DOE also
noted that water heaters with demandresponse capabilities may undergo
utility-initiated overheating during
certain periods to store additional
energy in the water heater during peak
demand periods, and tentatively
determined that the test provisions
proposed for water heaters that overheat
may not be appropriate for demandresponse water heaters that overheat. Id.
To distinguish demand-response water
heaters from other types capable of
overheating, DOE proposed to define a
‘‘demand-response water heater’’ as
follows:
Demand-response water heater means
a storage-type water heater that—
1. Has integrated communications
hardware and additional hardware and
software required to enable connected
functionality with a utility or third
party, that dispatches signals with
demand response instructions and/or
price signals to the product and receives
messages from the demand-response
water heater;
2. Meets the communication and
equipment standards for Consumer
Technology Association (CTA) Standard
2045–B (ANSI/CTA–2045–B); 24
3. Automatically heats the stored
water above the delivery temperature
setpoint only in response to instructions
received from a utility or third party.
87 FR 42270, 42280 (July 14, 2022). DOE
sought comment on this proposed
definition. Id.
22 The term ‘‘overheating’’ refers to raising the
tank temperature above the outlet water setpoint
and does not denote performance outside of the
normal operating range of the water heater.
23 While typical water heaters do not store water
warmer than the outlet temperature setpoint (which
is, on average, 125 ± 5 °F), water heaters designed
to increase energy storage capacity may overheat
the tank to temperatures such as 140–150 °F and use
a mixing valve to temper the outlet water down to
the setpoint condition. The energy storage capacity
is proportional to both the size of the tank and the
temperature of the water within.
24 ANSI/CTA–2045–B, ‘‘Modular
Communications Interface for Energy
Management,’’ published February 2021. (Available
at: shop.cta.tech/products/https-cdn-cta-tech-ctamedia-media-ansi-cta-2045-b-final-2022-pdf) (Last
accessed Sept. 17, 2022).
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In response to the July 2022 SNOPR,
AHRI, A.O. Smith, BWC, and Rheem
recommended that DOE change its
definition of ‘‘demand-response water
heater’’ to be consistent with ENERGY
STAR and AHRI Standard 1430.25
(AHRI, No. 55 at p. 7; A.O. Smith, No.
51 at pp. 6–7; BWC, No. 48 at p. 2;
Rheem, No. 47 at p. 6) Specifically,
AHRI and A.O. Smith requested that
DOE define ‘‘demand-flexible water
heater’’ as ‘‘an electric resistance storage
water heater or heat pump water heater
with the capability to reduce, shed,
shift, load up, and modulate energy
consumption in response to a command
or instructions received from a utility or
third party.’’ (AHRI, No. 55 at p. 7; A.O.
Smith, No. 51 at pp. 6–7) BWC
requested that DOE use the ENERGY
STAR and AHRI Standard 1430
definitions of ‘‘demand-response’’ to
avoid manufacturer burden and allow
for easier future development of these
products. (BWC, No. 48 at p. 2) Rheem
further recommended that DOE seek
direct feedback from EPA’s ENERGY
STAR program. (Rheem, No. 47 at p. 6)
NYSERDA pointed out that DOE’s
proposed definition for ‘‘demandresponse water heater,’’ which states
that it cannot overheat as a result of
user-initiated operation, is an additional
requirement beyond ENERGY STAR’s
definitions. Accordingly, NYSERDA
urged DOE to define ‘‘overheating test
exempt water heaters’’ so as to avoid
creating market confusion, and the
commenter recommended that DOE
consider the power usage for
connectedness as included in the
ENERGY STAR water heater
specification, as it would allow utilities
to plan more effectively, encourage the
additional load to be minimal, and
inform consumers regarding anticipated
operating costs. (NYSERDA, No. 50 at p.
2)
NEEA indicated support for DOE’s
proposed definition of ‘‘demandresponse water heater’’ and the proposal
for demand-response water heaters to
meet the communication and equipment
standards for ANSI/CTA–2045. (NEEA,
No. 56 at pp. 2–3) AHRI, however,
indicated that DOE’s definition would
require compliance with the demandresponse program the water heater is
enrolled in, whereas other, non-DOE
definitions allow consumers to opt out.
(AHRI, No. 55 at p. 7) BWC and Rheem
requested that DOE remove the
requirement to comply with CTA–2045.
25 AHRI Standard 1430–2022 (I–P), ‘‘2022
Standard for Demand Flexible Water Heaters,’’
published December 2022. (Available at: https://
www.ahrinet.org/search-standards/ahri-1430demand-flexible-electric-storage-water-heaters.)
(Last accessed Feb. 17, 2023)
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(BWC, No. 48 at pp. 1–2, Rheem, No. 47
at p. 6) BWC stated that requiring
compliance with CTA–2045 may
prevent manufacturers from designing
their products around separate and
future protocols. (BWC, No. 48 at pp. 1–
2)
Rheem recommended that DOE’s
definition acknowledge the fact that
many water heaters with demandresponse capability are currently
shipped without all necessary hardware
to participate in a demand-response
program. Rheem also suggested that
DOE’s definition does not cover most
demand-response water heaters because
it excludes water heaters without the
ability to heat water above the setpoint.
(Rheem, No. 47 at p. 6)
After reviewing these comments from
stakeholders, DOE understands that, for
the purpose of demand-response
programs, utilities and manufacturers
would benefit from a standardized
definition of ‘‘demand-response water
heater,’’ specifically one that requires
certain communications protocols to be
present in order to be compatible with
the demand-response signals from the
utility or third-party. Stakeholders have
indicated that, in order to be deemed a
‘‘demand-response water heater,’’ a
product must demonstrate that it is
capable of executing the commands
from the demand-response signals (i.e.,
pass the verification tests in the
ENERGY STAR Test Method to Validate
Demand Response or in AHRI Standard
1430). However, DOE proposed a more
limited definition for ‘‘demand-response
water heater’’ in the July 2022 SNOPR,
seeking only to describe the types of
water heaters that could temporarily
increase the storage tank temperature as
a means to perform a load up 26 such
that this particular operation would not
be considered ‘‘overheating’’ in the
appendix E test procedure (see 87 FR
42270, 42280 (July 14, 2022)). This led
DOE to revisit its proposed definition
and to reassess its planned approach.
As a result, in this final rule, DOE has
decided not to establish a definition for
‘‘demand-response water heater.’’ DOE
has considered the various requirements
which stakeholders suggested should be
criteria for a product to be called a
‘‘demand-response water heater’’ and
has determined that, while
26 According to the ENERGY STAR Test Method
to Validate Demand Response v1.2, a connected
water heating product is required to use and/or
store additional thermal energy that the device
otherwise would not have used/stored under
normal operation in response to a load up request.
This allows the stored thermal energy to increase
within the safety parameters determined by the
manufacturer, and, for installations with a mixing
valve, the device may exceed the user set point
temperature.
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standardization of these requirements
may be beneficial to utilities and
industry, it is unnecessary at this time
because DOE can instead describe the
types of water heaters that can
temporarily increase the storage tank
temperature only in response to
instructions from a utility or third-party
demand response program without
defining ‘‘demand-response water
heater’’. Additionally, as discussed in
section III.E.1.b of this document, this
final rule only amends the test
procedure to provide a means for testing
water heaters in the highest tank
temperature setting, and DOE is
adopting it as a voluntary measure in
this test procedure for certain electric
storage water heaters. As such, it is no
longer necessary to establish a
definition for ‘‘demand-response water
heater’’ in this test procedure
rulemaking.
2. Heat Pump Water Heaters
As discussed in section III.A of this
document, EPCA defines ‘‘water heater’’
to include, in relevant part, (A) storage
type units which heat and store water at
a thermostatically controlled
temperature, including . . . electric
storage water heaters with an input of
12 kilowatts or less; (B) instantaneous
type units which heat water but contain
no more than one gallon of water per
4,000 Btu per hour of input, including
. . . electric instantaneous water heaters
with an input of 12 kilowatts or less;
and (C) heat pump type units, with a
maximum current rating of 24 amperes
at a voltage no greater than 250 volts,
which are products designed to transfer
thermal energy from one temperature
level to a higher temperature level for
the purpose of heating water, including
all ancillary equipment such as fans,
storage tanks, pumps, or controls
necessary for the device to perform its
function. (42 U.S.C. 6291(27))
Because the maximum current and
voltage ratings for consumer heat pump
type units are 24 amperes at no more
than 250 volts, the maximum electrical
input for this type of product is
determined to be 6 kilowatts.27 In this
final rule, DOE is providing
clarifications on how these definitions
apply to electric and gas-fired heat
pump storage water heaters.
a. Electric Heat Pump Storage Water
Heaters
EPCA is not explicit as to whether
heat pump type units are considered a
subcategory of storage type units and
27 Power equals current times voltage, so the
definition of consumer heat pump type unit
corresponds to a maximum power rating of 6,000
W, or 6 kW (i.e., 24 A times 250 V equals 6,000 W).
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instantaneous type units. ‘‘Storage type
units’’ and ‘‘instantaneous type units’’
are not exclusive of ‘‘heat pump type
units.’’ Based on the statute’s ‘‘water
heater’’ definition, an electric heat
pump type unit could be covered under
the ‘‘water heater’’ definition’s
description of storage type units (if it
heats and stores water at a
thermostatically controlled temperature
with an input of 12 kilowatts or less) or
instantaneous type unit (if it heats water
and contains no more than one gallon of
water per 4,000 Btu per hour of input
and has an input of 12 kilowatts or less).
On November 10, 2016, DOE
published a final rule in the Federal
Register (the November 2016 Final
Rule) that treated heat pump-type units
as a subcategory of the other two types
of units listed in the definition of water
heater. Specifically, DOE stated in the
November 2016 final rule that a heat
pump water heater with a total rated
input of less than 12 kilowatts would be
a consumer water heater because EPCA
classifies electric water heaters with less
than 12 kilowatts rated electrical input
as consumer water heaters. 81 FR 79261,
79301–79302. In the January 2022
NOPR, DOE responded to comments
requesting clarification on whether
electric heat pump water heaters
between 6 kilowatts and 12 kilowatts of
input should be classified as consumer
water heaters or commercial water
heaters. 87 FR 1554, 1561–1563 (Jan. 11,
2022). Upon further review of EPCA and
the water heater market, DOE initially
determined in the January 2022 NOPR
that the interpretation presented in the
November 2016 Final Rule was not the
best reading of EPCA. Id.
In the January 2022 NOPR, DOE
explained that the structure of the
statutory definition of ‘‘water heater’’ in
the Energy Conservation Program for
Consumer Products in Part A of EPCA
lists each type of water heater at equal
subparagraph designations. Therefore,
when defining ‘‘water heater’’ for the
purpose of determining whether a water
heater is a consumer water heater, the
energy use criteria specified for heat
pump-type units is to be applied
separately and distinctly from the
criteria specified for the categorizations
of storage-type units and instantaneoustype units. Therefore, DOE had
tentatively determined that heat pump
water heaters, which operate with a
maximum current rating greater than 24
amperes or at a voltage greater than 250
volts, are more appropriately covered as
commercial water heaters than
consumer water heaters. 87 FR 1554,
1561–1562 (Jan. 11, 2022).
As explained in the January 2022
NOPR, there are three other reasons why
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DOE tentatively concluded that the
revised interpretation would be more
applicable to the residential water
heater market.
First, heat pump technology is
capable of providing heat output which
exceeds the energy input. A heat pump
type unit with an input rate of 12
kilowatts could have a heating capacity
(i.e., output capacity) of approximately
42 kilowatts, which is 3.6 times the
output heating capacity provided by the
largest possible consumer electric
storage type water heater (i.e., 11.8
kilowatts).28 While a heat pump-type
unit with a 12 kilowatt input capacity
could theoretically be designed and
installed in a residential application, its
water heating capacity (i.e., output
capacity) would far exceed the water
heating demand of any residential
installation. 87 FR 1554, 1562 (Jan. 11,
2022).
Second, the DOE test procedure for
consumer water heaters at the time of
the November 2016 Final Rule only
covered heat pump water heaters which
have ‘‘a maximum current rating of 24
amperes (including the compressor and
all auxiliary equipment such as fans,
pumps, controls, and, if on the same
circuit, any resistive elements) for an
input voltage of 250 volts or less,’’ and,
therefore, electric heat pump water
heaters with greater than 24 amperes at
250 volts were not considered at the
time when the current energy
conservation standards for consumer
water heaters were established (April
2010). As a result, these current
standards do not reflect energy usage for
heat pump water heaters between 6
kilowatts and 12 kilowatts, and such
products are more appropriately rated to
the commercial water heater test
procedure (10 CFR 431.106) and
evaluated against the maximum standby
loss standards for this equipment (10
CFR 431.110(a)). 87 FR 1554, 1562 (Jan.
11, 2022).
Third, based on its review of the
market, DOE is aware of integrated heat
pump water heaters, split-system heat
pump water heaters, and heat pumponly water heaters (i.e., circulating heat
pump water heaters) which are designed
for use in residential applications, and
all such products are rated at or below
24 A/250 V of input. Integrated heat
28 A 12-kW electric resistance water heater with
an assumed recovery efficiency of 98 percent would
have an output heating capacity of 11.8 kW (12 kW
× 0.98 = 11.8 kW). An electric heat pump-type
water heater with a 12-kW input capacity, with an
assumed recovery efficiency of 350 percent, would
have an output heating capacity of 42 kW (12 kW
× 3.5 = 42 kW), which is 3.6 times greater than the
11.8 kW output heating capacity of an electric
resistance water heater with equivalent input
capacity.
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pump water heaters, which consist of an
air-source heat pump in one assembly
with a storage tank, typically operate
with 240-volt input. Although
integrated heat pump water heaters
usually have backup 4.5-kilowatt
electric resistance heating elements, the
elements do not operate simultaneously,
which ensures that these products do
not surpass 6 kilowatts of input or 24 A/
250 V at any given time. Some
integrated heat pump water heaters are
designed to operate at only 120 volts of
input (i.e., ‘‘retrofit-ready,’’ ‘‘plug-in,’’
or ‘‘120-volt’’ heat pump water heaters).
Split-system heat pump water heaters,
which consist of a separate heat pump
and storage tank that are sold together
(where the heat pump components are
usually situated outdoors), are also
covered by the currently applicable
appendix E test procedure and have
electrical input ratings which do not
exceed 24 A/250 V. Circulating heat
pump water heaters (or ‘‘heat pumponly’’ water heaters), which consist of
only a heat pump module and must be
installed with a separate storage tank,
similarly do not exceed this limit, and
there are models of circulating heat
pump water heaters which are intended
to operate on 120 volts of input.
Alternative source heat pump water
heaters (e.g., ground-source or watersource), were not considered in this
rulemaking due to their predominant
use as commercial products. 87 FR
1554, 1563 (Jan. 11, 2022).
In this final rule, DOE maintains the
revised interpretation as discussed in
the January 2022 NOPR. To clarify this
interpretation in the regulatory
definitions, DOE is amending the
definition of ‘‘commercial heat pump
water heater’’ at 10 CFR 431.102 to
reflect this revised interpretation. The
revised definition reads: ‘‘Commercial
heat pump water heater (CHPWH)
means a water heater (including all
ancillary equipment such as fans,
blowers, pumps, storage tanks, piping,
and controls, as applicable) that uses a
refrigeration cycle, such as vapor
compression, to transfer heat from a
low-temperature source to a highertemperature sink for the purpose of
heating potable water, and operates with
a current rating greater than 24 amperes
or a voltage greater than 250 volts. Such
equipment includes, but is not limited
to, air-source heat pump water heaters,
water-source heat pump water heaters,
and direct geo-exchange heat pump
water heaters.’’
In the April 2020 RFI, DOE requested
feedback on the need for creating a
separate definition for ‘‘electric heat
pump storage water heater,’’ similar to
the definition in the March 2019
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ASHRAE Draft 118.2, or whether the
current DOE definitions in 10 CFR 430.2
for ‘‘electric storage water heater’’ and
‘‘water heater,’’ which include ‘‘heat
pump type units,’’ would adequately
cover such products for the purpose of
performing the DOE test procedure. 85
FR 21104, 21110 (April 16, 2020). The
Department’s tentative determination in
the January 2022 NOPR was that a
separate definition would not be needed
because the current definitions were
sufficient to describe these products. 87
FR 1554, 1563–1564 (Jan. 11, 2022). In
response to the January 2022 NOPR,
Rheem requested that the product classspecific definitions include or refer to
the ‘‘heat pump type’’ requirements in
EPCA. (Rheem, No. 31 at p. 2) BWC
agreed with DOE’s assessment that
consumer heat pump water heaters
operate at no greater than 24 amperes at
250 volts. (BWC, No. 33 at pp. 1–2)
Additionally, DOE received several
comments on the January 2022 NOPR
regarding definitions for specific types
of heat pump water heaters used in
residential applications.
The CA IOUs recommended that DOE
should supplement its test procedure
definitions to address heat pump water
heaters rated to operate at 120 volts of
input. More specifically, the CA IOUs
recommended that DOE develop a
separate definition for 120-volt heat
pump water heaters in the test
procedure and consider any
distinguishing characteristics that might
require changes to the test procedure to
represent their real-world performance
accurately. These commenters argued
that a separate definition would allow
for the possibility of separate energy
conservation standards for these
products. The CA IOUs stated that they
expect the first 120-volt heat pump
water heaters to appear on the retail
market in 2022 and noted that the
California Energy Commission recently
adopted a goal to install six million heat
pumps (for space and water heating) by
2030, many of which they anticipate
will be 120-volt heat pump water
heaters. (CA IOUs, No. 36 at p. 4)
AET expressed support for the
inclusion of heat pump-only water
heaters within the scope of the DOE test
procedure but suggested revising the
terminology so as to differentiate a ‘‘heat
pump water heater without a tank’’ from
a ‘‘heat pump water heater with a tank.’’
(AET, No. 29 at p. 2) On this point, DOE
notes that there is not yet a particular
term for these products defined at 10
CFR 430.2 or in appendix E. These
products may be referred to using any
of the terms mentioned by AET, but the
clearest description of these products is
‘‘circulating heat pump water heaters.’’
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Circulating water heaters are discussed
further in section III.A.4.a of this
document. DOE is adopting a definition
for ‘‘circulating water heater’’ in this
final rule, which will include these
products.
Rheem recommended that DOE
include split-system heat pump water
heaters in the ‘‘water heaters requiring
a storage tank’’ definition proposed in
the January 2022 NOPR and that DOE
define ‘‘integrated heat pump water
heater’’ to distinguish them from splitsystem water heaters. (Rheem, No. 47 at
p. 4) AHRI stated that a definition of
‘‘split-system water heater’’ is not
required if DOE does not include the
proposed optional additional test
conditions in this rulemaking. (AHRI,
No. 55 at p. 5)
In response to Rheem’s comments, a
split-system water heater is not
necessarily a ‘‘water heater requiring a
storage tank,’’ as proposed in the
January 2022 NOPR, because for a water
heater to meet the proposed definition
of ‘‘water heater requiring a storage
tank’’ would mean there is no storage
tank specified or supplied by the
manufacturer but that it requires one for
testing and operation. A split-system
water heater, however, may have a
manufacturer supplied or specified tank
and, as such, would not necessarily fall
under the definition of a ‘‘water heater
requiring a storage tank.’’ When the tank
is specified or supplied by the
manufacturer, that tank should be used
for testing, rather than a water heater or
storage tank that meets the default
conditions that were proposed to be
added in section 4.10 of appendix E.
Additionally, in response to the
suggestion that DOE define ‘‘integrated
heat pump water heater,’’ DOE notes
that, as discussed later in this section,
it is modifying the definition of a ‘‘splitsystem water heater’’ based on
comments to mean a heat pump-type
water heater in which at least the
compressor, which may be installed
outdoors, is separate from the storage
tank. Therefore, heat pump water
heaters that do not fall under the
definition of ‘‘split-system water heater’’
adopted in this final rule would be
integrated heat pump water heaters, as
the refrigeration components would be
integrated with the tank. Thus, it is
unnecessary to separately define
‘‘integrated heat pump water heaters,’’
and the term would not be used in the
test method. Creating additional
definitions for this configuration may
lead to confusion. In response to AHRI’s
comment, as discussed and for the
reasons explained in section III.C.7 of
this document, DOE has decided to
include the proposed optional
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additional test conditions in this
rulemaking, and, thus, the Department
has defined the term ‘‘split-system water
heater.’’
A.O. Smith requested that DOE
clearly define ‘‘heat pump-only water
heater’’ and elucidate how appendix E
applies to them. (A.O. Smith, No. 51 at
p. 5) BWC requested that DOE clarify in
its definitions the difference between
split-system and heat pump-only water
heaters. (BWC, No. 48 at p. 1)
In response, a heat pump-only water
heater is considered a circulating water
heater, which is a type of heat pump
water heater, falls under the circulating
water heater product classes, and is
covered under the associated provisions
of appendix E. Such distinctions were
previously discussed in the January
2022 NOPR. 87 FR 1554, 1565 (Jan. 11,
2022). These units have an input greater
than or equal to 4,000 Btu per hour per
gallon, and accordingly, they are
considered instantaneous water heaters.
In contrast, split-system heat pump
water heaters (which, unlike heat pumponly units, are distributed with a storage
tank) are considered storage water
heaters.
After considering these comments,
DOE has decided to affirm coverage in
this test procedure final rule for all of
the aforementioned types of consumer
heat pump water heaters. In particular,
DOE has determined that the current
definitions of ‘‘heat pump-type’’ and
‘‘electric storage water heater’’
adequately cover the electric heat pump
water heaters on the market that are
representative of residential use
(including, but not limited to, integrated
240-volt and 120-volt heat pump water
heaters, split-system heat pump water
heaters, and circulating heat pump
water heaters), and that a separate
definition for ‘‘electric heat pump water
heaters’’ is not needed in order to
appropriately characterize the test
procedure for consumer water heaters
and residential-duty commercial water
heaters.
At the time of this final rule, DOE is
only aware of a small number of 120volt integrated heat pump water heaters
and circulating heat pump water heaters
on the market. Therefore, DOE has
limited information to determine
whether there are any distinguishing
characteristics of these products which
would necessitate tailored test
procedure requirements in order to
produce ratings that are representative,
reproducible, and repeatable. One
manufacturer has publicly certified
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ratings 29 for 120-volt electric storage
heat pump models using the currently
applicable appendix E test procedure
(without the use of a test procedure
waiver), so DOE, therefore, concludes
that the appendix E test procedure is
appropriate and representative for these
models. DOE is aware, however, that
default mode operation of 120-volt
electric storage heat pump water heaters
may require raising the tank
temperature above the delivery setpoint
in order to meet consumer expectations
of first hour rating (FHR), and further
discussion of potential impacts of
storage tank overheating on ratings for
120-volt electric storage heat pump
water heaters as a result of this final
rule’s action can be found in section
III.E.1 and III.J.3 of this document.
In response to the July 2022 SNOPR,
which proposed optional ambient test
conditions and new definitions for
‘‘split-system water heaters,’’ AHRI and
A.O. Smith requested that DOE change
its definition of ‘‘split-system water
heater’’ to the definition used by
ENERGY STAR, which specifies that the
compressor, evaporator, and/or
condenser are separated from a storage
tank that is specified by the
manufacturer and rated as a single
system. (AHRI, No. 55 at p. 5; A.O.
Smith, No. 51 at p. 4) A.O. Smith
offered an alternative definition to
DOE’s earlier definition of ‘‘split-system
heat pump water heater’’ which
specified the heat pump as being an
outdoor component. (A.O. Smith, No. 51
at pp. 4–5)
A.O. Smith, NEEA, and the CA IOUs
stated that it is unnecessary for the
definition of ‘‘split-system water heater’’
to specify the location of specific
components and requested that DOE
eliminate the distinction between
indoor and outdoor components. (A.O.
Smith, No. 51 at p. 5; CA IOUs, No. 52
at pp. 4–5; NEEA, No. 56 at p. 2) The
CA IOUs stated that the compressor
should be specified as the component
separate from the storage tank, rather
than the heat pump, to more generally
reflect split-system water heaters. (CA
IOUs, No. 52 at pp. 4–5)
NEEA additionally recommended that
DOE should not include references to
‘‘indoor’’ or ‘‘outdoor’’ in its proposed
definition of ‘‘split-system heat pump
water heater,’’ as outdoor installation of
the heat pump component does not
necessarily follow the splitting of
heating and storage functions into
separate components, and an all-indoor
29 DOE reviewed public certification data in its
Compliance Certification Management System
(CCMS) database, found online at
www.regulations.doe.gov/certification-data/
#q=Product_Group_s%3A*.
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split-system HPWH has the potential to
provide significant benefits to
consumers. NEEA added that adopting a
split-system definition that excludes
such products could hinder
manufacturers in bringing them to
market. (NEEA, No. 56 at p. 2) Similarly,
Nyle commented that the proposed
definition is problematic because not all
split-system heat pump water heaters
contain an outdoor component, noting
that it manufactures a 120-volt heat
pump water heater for indoor use only.
Nyle suggested revising the definition to
indicate that a split-system heat pump
water heater means a heat pump-type
water heater where the storage unit and
heat pump components are independent
from one another but must be connected
to operate (i.e., through refrigerant lines,
water piping, or via a thermal storage
device). (Nyle, No. 57 at p. 1)
In order to address the need for
separate test conditions for split-system
water heaters (see section III.C.7 of this
document for a discussion on optional
test conditions, which simulate different
indoor and outdoor air conditions for
the different components of a splitsystem water heater), DOE is adopting a
definition for this subset of heat pump
water heaters at 10 CFR part 430,
subpart B, appendix E, section 1.14.
In response to these comments, DOE
acknowledges that it is not necessary to
specify the location of the components
and/or the storage tank in the definition
of ‘‘split-system heat pump water
heater’’ as long as they are separate.
Therefore, DOE has changed the
definition of ‘‘split-system heat pump
water heater’’ to mean a heat pump-type
water heater in which at least the
compressor, which may be installed
outdoors, is separate from the storage
tank. This definition still reflects that
which is used in NEEA’s Advanced
Water Heating Specification (AWHS)
version 8.0 (AWHS v8.0),30 with minor
modifications.
Additionally, a new definition for
‘‘circulating water heater’’ is being
established in this final rule at 10 CFR
430.2, as discussed in section III.A.4.a of
this document. This product category
includes heat pump-only water heaters,
30 AWHS v8.0 was published by NEEA on March
1, 2022. Although early editions of the AWHS
focused primarily on providing more representative
performance metrics for heat pump water heaters in
cold climates, the latest editions are now more
broadly focused on providing representative
performance metrics for heat pump water heaters
across all climates. AWHS v8.0 includes separate
test condition requirements for integrated and splitsystem heat pump water heaters. These test
conditions are discussed further in detail in section
III.C.1 of this final rule. (Available at: neea.org/
resources/advanced-water-heating-specificationv8.0) (Last accessed on Sept. 19, 2022).
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which is also discussed in section
III.A.4.a of this document. Specific
testing provisions for circulating water
heaters are being newly established in
this final rule, as discussed in section
III.D.4 of this document.
b. Gas-Fired Heat Pump Storage Water
Heaters
The statutory definition for a ‘‘heat
pump type’’ water heater (see 42 U.S.C.
6291(27)(C)) is not specific to electric
heat pump type water heaters. Gas-fired
heat pump storage water heaters
typically use an absorption or
adsorption refrigeration cycle, driven by
a gas burner, to transfer heat from the
surrounding air to the water inside the
water heater.
In the July 2014 Final Rule, DOE
codified a definition for ‘‘gas-fired heat
pump water heater’’ as follows:
Gas-fired heat pump water heater
means a water heater that uses gas as the
main energy source, has a nameplate
input rating of 75,000 Btu/h (79 MJ/h)
or less, has a maximum current rating of
24 amperes (including all auxiliary
equipment such as fans, pumps,
controls, and, if on the same circuit, any
resistive elements) at an input voltage of
no greater than 250 volts, has a rated
storage volume not more than 120
gallons (450 liters), and is designed to
transfer thermal energy from one
temperature level to a higher
temperature level to deliver water at a
thermostatically controlled temperature
less than or equal to 180 °F (82 °C). 79
FR 40542, 40567 (July 11, 2014).
Then, in the November 2016 Final
Rule, DOE reasoned that even though
gas-fired heat pump water heaters were
covered by the existing test procedure,
this definition was extraneous because
it is not specifically referenced in any
part of DOE’s test procedures or energy
conservation standards for consumer
water heaters. 81 FR 79261, 79261,
79287 (Nov. 10, 2016). The definition
for ‘‘gas-fired heat pump water heater’’
was deleted, and the current definition
for ‘‘gas-fired storage water heater’’ was
added instead. Id. at 81 FR 79320–
79321.
Since the deletion of the definition in
the November 2016 Final Rule,
ASHRAE published an updated version
of the test standard 118.2, ‘‘Method of
Testing for Rating Residential Water
Heaters and Residential-Duty
Commercial Water Heaters,’’ in January
2022 (ASHRAE 118.2–2022) (see section
III.B.2 for further discussion of this
standard). The January 2022 NOPR
issued prior to publication of ASHRAE
118.2–2022 and assessed public review
drafts of ASHRAE 118.2–2022—all of
which still included a definition for
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‘‘gas-fired heat pump storage water
heater.’’ The definition for ‘‘gas-fired
heat pump storage water heaters’’ in the
public review drafts of ASHRAE 118.2–
2022 was adopted in section 2.4 of the
final published version, which defines
the term as follows:
(a) Use gas as the main energy source,
(b) Have a nameplate input rating of
20,000 Btu/h (26.4 MJ/h) or less,
(c) Have a maximum current rating of
24 amp (including all auxiliary
equipment, such as fans, pumps,
controls, and, if on the same circuit, any
resistive elements) at an input voltage of
no greater than 250 V,
(d) Have a rated storage volume not
more than 120 gal (450 L), and
(e) Are designed to transfer thermal
energy from one temperature level to a
higher temperature level to deliver
water at a thermostatically controlled
temperature less than or equal to 180 °F
(82 °C).
In the January 2022 NOPR, DOE
stated that, currently, a water heater that
uses gas as the main energy source, has
a nameplate input rating of 75,000 Btu/
h or less, and contains more than one
gallon of water per 4,000 Btu per hour
of input is a gas-fired storage water
heater. (10 CFR 430.2) If the gas-fired
storage water heater also has a heat
pump with a maximum current rating of
24 amperes at a voltage no greater than
250 volts, is designed to transfer thermal
energy from one temperature level to a
higher temperature level for the purpose
of heating water, including all ancillary
equipment such as fans, storage tanks,
pumps, or controls necessary for the
device to perform its function, it would
be a heat pump type unit (see 10 CFR
430.2). 87 FR 1554, 1564 (Jan. 11, 2022).
DOE also noted in the January 2022
NOPR that this industry definition
establishes the scope of coverage for
these products more narrowly than the
current definitions for ‘‘gas-fired storage
water heater’’ and ‘‘heat pump type’’
water heater together. Specifically, the
ASHRAE 118.2–2022 definition limits
the input rate at 20,000 Btu/h—
presumably because the input rates of
models currently in development for
residential applications are less than
20,000 Btu/h—whereas the current
definitions at 10 CFR 430.2
accommodate potential future products
up to 75,000 Btu/h. In recognition of the
developing market for gas-fired heat
pump water heaters, DOE had
tentatively determined not to limit
scope of coverage to only 20,000 Btu/h.
87 FR 1554, 1564 (Jan. 11, 2022).
In response to the January 2022
NOPR, BWC suggested DOE re-evaluate
whether current consumer water heater
definitions adequately cover gas-fired
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heat pump water heaters (as defined by
ASHRAE) in light of questions as to
whether features related to these
products depart from the current
consumer water heater definitions.
(BWC, No. 33 at p. 2) However, the
commenter did not provide further
details.
DOE did not receive any additional
comments elucidating which features
may be of concern, and as a result, DOE
is not able to identify reasons to justify
redefining gas-fired heat pump storage
water heaters in a way that departs from
the current definitions. At the time of
this final rule, such products are still
mostly in the field trial stage in the
United States, and, thus, they are not
mass-produced, nor are they widely
distributed in the commercial market.
However, DOE is aware that products
currently under development consist of
a modulating gas-fired burner that
powers an absorption cycle using a
design which would meet the definition
for a ‘‘split-system heat pump water
heater’’ (discussed in section III.A.2.a of
this document). Nonetheless, because
the current definitions for ‘‘gas-fired
storage water heater’’ and ‘‘heat pump
type’’ water heater are sufficiently
broad, such products would remain
appropriately encompassed within the
current scope of coverage. Should more
designs of gas-fired heat pump water
heaters (either storage type or
instantaneous type) emerge into the
water heaters market, DOE would
evaluate the definitions and
appropriateness of its test methods for
gas-fired and heat pump products as
they would apply to this novel
technology.
Moreover, while ASHRAE 118.2–2022
does define gas-fired heat pump storage
water heaters, there are no unique test
methods for these products outlined in
the industry test standards. Similar to
the determination in the November 2016
Final Rule, DOE has concluded that the
definition in ASHRAE 118.2–2022 is
extraneous. Furthermore, given that no
concrete concerns regarding the
applicability of the current methods to
gas-fired heat pump water heaters have
been identified, DOE has determined
not to adopt any specific provisions for
these in its amended appendix E test
procedure at this time.
3. Residential-Duty Commercial Water
Heaters
In this rulemaking, DOE has sought
comment on the definition for
‘‘residential-duty commercial water
heater,’’ which defines a category of
commercial water heaters that are
subject to the appendix E test procedure
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due to their residential applications. 85
FR 21104, 21108 (April 16, 2020).
In the January 2022 NOPR, DOE
acknowledged that some water heaters
intended for commercial use are
covered by the residential-duty
commercial water heater definition and
tested and rated to the appendix E test
procedure and residential-duty
commercial water heater energy
conservation standards in terms of UEF.
DOE explained that these water heaters
have characteristics that are similar to
water heaters with residential
applications and, as such, under 42
U.S.C. 6295(e)(5)(F), cannot be excluded
from being tested and rated using the
consumer water heaters test procedure
and residential-duty commercial water
heater energy conservation standards.
Thus, DOE did not propose
amendments to this definition. 87 FR
1554, 1566 (Jan. 11, 2022).
DOE has determined that whether a
product is marketed as commercial or
residential may not always be indicative
of the intended installation location.
The January 2022 NOPR provided the
example of water heaters that are
intended for residential use but
sometimes marketed as ‘‘commercialgrade’’ as a means to convey an
expectation of reliability. 87 FR 1554,
1566–1567 (Jan. 11, 2022).
In commenting on the January 2022
NOPR, with regards to residential-duty
commercial water heaters, AET
commented that the method used to
evaluate consumer electric
instantaneous and residential-duty
commercial electric instantaneous water
heaters in the December 2016
Conversion Factor Final Rule was not
approved for these products, and the
energy conservation standards DOE
issued for consumer water heaters could
not be met by them. AET argued that the
energy conservation standards for
residential-duty commercial electric
instantaneous water heaters were based
on performance for fossil fuel-fired
commercial tankless water heaters as
opposed to actual product testing, and,
therefore, the commenter asserted that
the minimum efficiency requirements
for residential-duty commercial electric
instantaneous water heaters are too low
and should be updated. (AET, No. 29 at
pp. 14–15)
DOE understands that the
commenter’s discussion of the ‘‘method
used to evaluate consumer electric
instantaneous and residential-duty
commercial electric instantaneous water
heaters’’ refers to the analytical
approach in 2016 that was used to
predict the UEF values of these water
heaters from existing representations of
maximum GPM (see 81 FR 96204,
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92616–92617 (Dec. 29, 2016)) and
thermal efficiency (see 81 FR 96204,
96218 (Dec. 29, 2016)). At this time,
however, the current appendix E test
procedure does provide a method to test
and rate these water heaters.31 DOE
notes that there are currently consumer
and residential-duty commercial electric
instantaneous water heaters certified to
meet the applicable energy conservation
standards.
Otherwise, DOE did not receive any
comments specifically pertaining to the
definition for residential-duty
commercial water heaters. Therefore,
DOE is not amending the definition for
‘‘residential-duty commercial water
heater’’ in this final rule for the reasons
previously discussed. DOE may
consider potential amended standards
for residential-duty commercial electric
instantaneous water heaters in a
separate rulemaking addressing the
energy conservation standards for
commercial water heaters.32
4. Specialty Water Heaters
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As first proposed in the January 2022
NOPR, this final rule expands the scope
of coverage of the appendix E test
procedure to include low-temperature
water heaters and circulating water
heaters, which both fall under the
statutory definition of consumer ‘‘water
heater’’ but did not previously have test
methods appropriate for their unique
operation. DOE is also re-instating an
inadvertently omitted definition for
‘‘tabletop water heater’’ at 10 CFR 430.2.
In addition, DOE has considered
whether to address solar water heaters
in the consumer water heaters test
procedure, but the Department has
determined not to expand the scope of
coverage of the appendix E to these
products at this time. DOE may further
consider solar water heaters in a
separate rulemaking in the future. Each
of these categories of water heaters is
discussed in the following subsections.
Dyson generally commented that
indirect circulation systems especially
have an extraordinarily flexible use case
and can be implemented in both warm
and cool regions. (Dyson, No. 28 at p.
1) DOE understands this comment to
refer to systems which use a separate
boiler to provide the heat source for
domestic water heating. However,
31 Section 5.3.2 of appendix E details the Max
GPM rating test for flow-activated water heaters,
Table II in section 5.4.1 of appendix E details how
to select draw pattern based on Max GPM rating,
and sections 5.4.2 and 5.4.3 of appendix E detail the
test sequence.
32 DOE is concurrently evaluating energy
conservation standards for commercial water
heaters in Docket No. EERE–2021–BT–STD–0027.
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consumer boilers are not within the
scope of this rulemaking.
a. Circulating Water Heaters
As discussed in section III.A of this
document, a gas-fired instantaneous
water heater is a water heater that uses
gas as the main energy source, has a
nameplate input rating less than
200,000 Btu per hour, and contains no
more than one gallon of water per 4,000
Btu per hour of input. 10 CFR 430.2.
In the April 2020 RFI, DOE requested
feedback on the typical application of a
specific configuration of gas-fired
instantaneous water heaters, commonly
referred to as ‘‘circulating gas-fired
instantaneous water heaters.’’ 85 FR
21104, 21113 (April 16, 2020). As
explained in the April 2020 RFI, DOE
has found that several manufacturers
produce consumer gas-fired
instantaneous water heaters that are
designed to be used with a volume of
stored water (usually in a tank, but
sometimes in a recirculating hot water
system of sufficient volume, such as a
hydronic space heating or designated
hot water system) in which the water
heater does not provide hot water
directly to fixtures, such as a faucet or
shower head, but rather replenishes heat
lost from the tank or system through hot
water draws or standby losses by
circulating water to and from the tank
or other system. These circulating gasfired instantaneous water heaters are
typically activated by an aquastat 33
installed in a storage tank that is sold
separately or by an inlet water
temperature sensor. DOE further stated
that while the products identified by
DOE are within the statutory and
regulatory definition of a consumer
‘‘water heater’’ and, therefore, a covered
product, the design and application of
circulating gas-fired instantaneous water
heaters make testing to the currently
applicable Federal test procedure for
consumer water heaters difficult, if not
impossible, as these products are not
capable of delivering water at the
temperatures and flow rates specified in
the UEF test method contained therein.
Id. As a result, the currently applicable
appendix E test procedure does not
sufficiently cover circulating water
heaters.
DOE received several comments on
the April 2020 RFI recommending
generally that DOE amend the
regulatory definitions of gas-fired
instantaneous water heaters to exclude
models designed exclusively for
commercial use even though they have
33 An ‘‘aquastat’’ is a temperature measuring
device typically used to control the water
temperature in a separate hot water storage tank.
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input rates below the consumer water
heater input rate limit (i.e., ≤200,000
Btu/h). AHRI and individual
manufacturers commented that these
products are used in commercial
applications even though they may in
certain cases meet the statutory
definition for a consumer water heater,
and that the residential draw pattern
profiles may not be applicable. These
comments are discussed in detail in the
January 2022 NOPR. 87 FR 1554, 1565
(Jan. 11, 2022).
In the January 2022 NOPR, DOE noted
that 42 U.S.C. 6291(1) states that a
‘‘consumer product’’ means any article
of a type which, to any significant
extent, is distributed in commerce for
personal use or consumption by
individuals. DOE also stated that its
examination of product literature has
found that circulating water heaters are
predominately marketed for commercial
applications. However, the input rates
of many of the available models are
below the maximum input rate of a
consumer water heater and can,
therefore, be suitable for residential
applications. DOE noted that there exist
circulating heat pump water heaters
(heat pump-only water heaters) which
operate in the same manner as gas-fired
circulating water heaters but are clearly
marketed for residential applications.
Consequently, it is foreseeable that there
could be the potential for product
substitution into the consumer market.
For these reasons, DOE tentatively
determined that circulating water
heaters are covered ‘‘consumer
products.’’ 87 FR 1554, 1565 (Jan. 11,
2022).
In the January 2022 NOPR, DOE
proposed to include the following
definition at 10 CFR 430.2: ‘‘Circulating
water heater means an instantaneous or
heat pump-type water heater that does
not have an operational scheme in
which the burner, heating element, or
compressor initiates and/or terminates
heating based on sensing flow; has a
water temperature sensor located at the
inlet of the water heater or in a separate
storage tank that is the primary means
of initiating and terminating heating;
and must be used in combination with
a recirculating pump and either a
separate storage tank or water
circulation loop in order to achieve the
water flow and temperature conditions
recommended in the manufacturer’s
installation and operation instructions.’’
87 FR 1554, 1565 (Jan. 11, 2022).
Commenters had varying viewpoints
on this topic. AET expressed general
agreement with DOE’s proposal to add
a new definition and product category
for circulating water heaters. (AET, No.
29 at p. 1)
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Rheem supported the addition of a
definition for ‘‘circulating water heater’’
to 10 CFR 430.2 and accompanying test
procedures within appendix E for such
products that have residential
applications, but the commenter
emphasized that the division between
consumer and commercial water heaters
should be appropriately set. Rheem
argued that because a ‘‘circulating water
heater’’ must use a separate storage tank,
circulating water heater product classes
should be defined using the storage-type
unit input rate criteria (e.g., a gas-fired
circulating water heater with an input
rate at or below 75,000 Btu/h is a
consumer water heater and greater than
75,000 Btu/h is a commercial water
heater). Rheem also recommended
further investigation as to whether
certain capacities of storage-type water
heaters could be covered by the
‘‘circulating water heater’’ definition.
Rheem added that the ‘‘circulating water
heater’’ definition should be amended to
allow a water temperature sensor at the
outlet of the water heater. (Rheem, No.
31 at p. 2)
BWC generally disagreed with DOE’s
proposal that circulating water heaters
should be covered as consumer
products, arguing that these products
are exclusively installed in commercial
applications as either part of a
recirculation loop or coupled to an
unfired hot water storage tank. BWC
also noted that circulating water heaters
heat water to higher temperatures than
consumer instantaneous water heaters
do. BWC argued that classifying
circulating water heaters as consumer
products would provide little to no
benefit to consumers, place additional
burden on manufacturers, and cause
market confusion as to how these
products are specified and designed for
field applications. (BWC, No. 33 at pp.
1–2)
AHRI expressed concerns about
including circulating water heaters in a
residential water heaters test procedure
because they are mostly used in
commercial applications, even with
input rates below 200,000 Btu/h. In lieu
of a solution in the test procedure, AHRI
requested that DOE reinstate the
enforcement policy on circulating water
heaters.34 (AHRI, No. 40 at p. 5) A.O.
Smith provided similar comments,
suggesting that DOE should reissue the
September 5, 2019 enforcement policy
for gas-fired circulating water heaters, or
alternatively identify them in the test
procedure as ‘‘historically regulated as
commercial water heating equipment’’
34 DOE had issued an enforcement policy for
circulating water heaters that expired on December
31, 2021.
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that ‘‘can be tested via the thermal
efficiency energy metrics; and . . .
therefore should not be subjected to
UEF requirements.’’ (A.O. Smith, No. 37
at pp. 2–3) Like AHRI and A.O. Smith,
BWC recommended reinstating the
September 2019 enforcement policy to
allow industry to determine the proper
test procedure. (BWC, No. 33 at pp. 1–
2)
EEI requested more information on
the size of the existing stock and current
sales volumes of circulating water
heaters. (EEI, Jan. 27, 2022 Public
Meeting Transcript, No. 27 at pp. 46–47)
In response, the Department reiterates
that EPCA directed DOE to develop a
test procedure that applies, to the
maximum extent practicable, to all
water heating technologies in use and to
future water heating technologies. (42
U.S.C. 6295(e)(5)(H)) As a circulating
water heater could be designed to
operate in a similar manner to other
consumer water heaters (i.e., ‘‘heat
pump-only’’ water heaters) and at
conditions appropriate for residential
applications, DOE is required to address
these products in appendix E with other
classes of consumer water heaters.
Furthermore, the definition for
‘‘consumer product’’ states that it is an
article ‘‘of a type’’ that is distributed for
personal use or consumption by
individuals ‘‘without regard to whether
such article of such type is in fact
distributed in commerce for personal
use or consumption by an individual.’’
(42 U.S.C. 6291(1))
In response to Rheem’s comment,
circulating water heaters have high
input rate to storage volume ratios,
which classify these products as
instantaneous-type water heaters (see 10
CFR 430.2 and 42 U.S.C. 6291(27)(B)).
As such, the statutory definition of a
storage-type water heater (found at 42
U.S.C. 6291(27)(A)) does not cover
circulating water heaters because
circulating water heaters have no more
than one gallon of water per 4,000 Btu/
h of input. As a result, the 75,000 Btu/
h upper limit on the input rate for gasfired storage-type water heaters would
not apply and will not be included in
the scope of the definition of
‘‘circulating water heater.’’
In response to BWC’s comments, DOE
notes that hot water delivery
temperature is not related to the
statutory definition of coverage. Rather,
EPCA defines whether a water heater is
covered as a consumer product
primarily according to its input rating,
without regard to its maximum hot
water delivery temperature. DOE also
concludes that classifying circulating
water heaters (that meet the input rating
requirements) as consumer products
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would provide a benefit to consumers
by allowing them to compare circulating
water heaters alongside other consumer
water heaters with a UEF rating. Under
42 U.S.C. 6293(b), EPCA requires that
DOE test procedure not place undue
burden on manufacturers. In this
instance, although test burden would
increase for manufacturers of circulating
water heaters, it would not be
considered an undue burden, because
these water heaters are consumer
products (by definition) and, therefore,
should be subject to consumer water
heater test procedures. Contrary to
BWC’s assertion, DOE concludes that
covering circulating water heaters as
consumer products would reduce or
resolve market confusion surrounding
these products; since they can be used
in residential applications, they should
be rated accordingly.
In response to A.O. Smith’s comment
requesting DOE to consider circulating
gas-fired water heaters as historically
regulated as commercial water heaters
and sufficiently described by the
commercial water heater metrics, DOE
is not expanding the scope to products
which are ‘‘historically regulated as
commercial water heating equipment’’
because DOE is only considering
circulating gas-fired water heaters with
input rates less than or equal to 200,000
Btu/h, which meet the existing statutory
definition for consumer water heaters
(and, thus, do not meet the definition
for gas-fired instantaneous commercial
water heaters). Furthermore, DOE
clarifies that the Department is not
considering these gas-fired circulating
water heaters (ones which meet the
existing statutory definition for
consumer water heaters) to be
residential-duty commercial water
heaters.
In response to the July 2022 SNOPR,
BWC and AHRI once again reiterated
their understanding that circulating
water waters are used almost
exclusively in commercial applications.
(BWC, No. 48 at p.4; AHRI, No. 55 at p.
5) BWC requested that DOE exercise
authority granted under the American
Manufacturing Technical Corrections
Act (AEMTCA) (42 U.S.C. 6295(e)(5)(F))
to regulate circulating water heaters as
commercial products even though they
meet residential definitions, or clearly
demonstrate residential use. (BWC, No.
48 at p. 4) AHRI suggested that
addressing circulating water heaters in a
consumer rulemaking would cause
confusion because their efficiency
metric is different from conventional
consumer water heaters. (AHRI, No. 55
at p. 5)
In response, EPCA allows DOE to
provide an exclusion from the uniform
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efficiency descriptor for specific
categories of otherwise covered water
heaters that do not have residential
uses, that can be clearly described, and
that are effectively rated using the
current thermal efficiency and standby
loss descriptors. (42 U.S.C.
6295(e)(5)(F)(i)) 35 However, DOE reads
this statutory provision as only
permitting exclusion of water heaters
that were categories of covered
commercial water heaters under section
342(a)(5) of EPCA [42 U.S.C. 6313(a)(5)].
It does not grant DOE authority to
exclude consumer water heaters from
the ambit of the uniform test procedure,
nor to somehow convert consumer
water heaters to commercial water
heaters and to subject them to energy
conservation standards applicable to
commercial water heaters. In the present
case, it is clear that the circulating water
heaters in question are consumer water
heaters, given that they have input rates
below 200,000 Btu/h, and they
otherwise meet the definitional criteria
of the statute for an instantaneous-type
water heater (see 42 U.S.C. 6291(27)(B)).
Moreover, circulating water heaters
have the demonstrated ability to
perform tank loading or recirculating
loop operation, as would indicate that
these products do have clearly
described residential uses.
Consequently, in response to these
comments, DOE notes that because both
heat pump-only and gas-fired
circulating water heaters meet the
requirements to be classified as
consumer products under EPCA, the
statute requires that such water heaters
must be tested according to DOE test
procedure at appendix E.
This final rule establishes a test
method to determine the UEF of
consumer circulating water heaters.
Effective and compliance dates are
discussed further in section III.I of this
document.
In development of this final rule, DOE
was not able to discern rates of
shipments and amount of stock for
consumer circulating water heaters as
EEI had requested. However, DOE did
identify circulating water heater models
currently on the market that are
consumer water heaters. DOE has
determined that circulating water
heaters may have a water temperature
35 DOE acted in accordance with EPCA provisions
as specified at 6295(e)(5)(F)(i) when establishing
product classes for residential-duty commercial
water heaters. In a July 2014 Final Rule establishing
the UEF test procedure, DOE determined that
covered commercial water heating equipment that
did not meet the definition of a ‘‘residential-duty
commercial water heater’’ met the criteria in EPCA
for exclusion from the uniform efficiency
descriptor. 79 FR 40542, 40545–40547 (July 11,
2014).
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sensor at the inlet or at the outlet of the
water heater—as suggested by Rheem—
and, therefore, the Department agrees
with Rheem and is adopting the
following definition for ‘‘circulating
water heater’’ at 10 CFR 430.2:
Circulating water heater means an
instantaneous or heat pump-type water
heater that does not have an operational
scheme in which the burner, heating
element, or compressor initiates and/or
terminates heating based on sensing
flow; has a water temperature sensor
located at the inlet or at the outlet of the
water heater or in a separate storage
tank that is the primary means of
initiating and terminating heating; and
must be used in combination with a
recirculating pump and either a separate
storage tank or water circulation loop in
order to achieve the water flow and
temperature conditions recommended
in the manufacturer’s installation and
operation instructions.
b. Low-Temperature Water Heaters
DOE has identified certain flowactivated water heaters that are designed
to deliver water at temperatures below
the set point temperature of 125 °F ±5 °F
(51.7 °C ±2.8 °C) that is required by
section 2.5 of the currently applicable
appendix E (hereinafter referred to as
‘‘low-temperature’’ water heaters).
These low-temperature water heaters
(often referred to as ‘‘handwashing’’ or
‘‘point-of-use’’ water heaters in
marketing literature) typically have low
heating rates, which requires the testing
agency to reduce the flow rate in order
to be able to achieve the outlet
temperature within the set point
temperature range. However, these units
also have a minimum activation flow
rate below which the unit shuts off. To
the extent that a unit would stop heating
water when the flow rate is too low,
there may be no flow rate at which the
unit would operate and deliver water at
the outlet temperature required under
section 2.5 of appendix E. Further, the
definition of water heater or electric
instantaneous water heater does not
include a minimum water delivery
temperature. To the extent that a lowtemperature water heater uses electricity
as the energy source, has a nameplate
input rating of 12 kilowatts or less, and
contains no more than one gallon of
water per 4,000 Btu per hour of input,
it would be an electric instantaneous
water heater. 10 CFR 430.2. Therefore,
because such products are within the
scope of consumer water heater
coverage under EPCA, the appendix E
test procedure should address them;
however, the currently applicable
appendix E does not address them.
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DOE requested information in the
April 2020 RFI on testing these products
at a lower set point temperature and
other potential changes which may be
necessary to accommodate these types
of models. 85 FR 21104, 21113 (April
16, 2020). Several commenters on the
April 2020 RFI recommended that the
test procedure be modified to indicate a
lower set point temperature for testing,
such as the maximum water
temperature delivery that the model is
capable of delivering (see NOPR
discussion for complete details). 87 FR
1554, 1582 (Jan. 11, 2022).
In the January 2022 NOPR, DOE
proposed to define a ‘‘low-temperature
water heater’’ as an electric
instantaneous water heater that is not a
circulating water heater and cannot
deliver water at a temperature greater
than or equal to the set point
temperature specified in section 2.5 of
appendix E to subpart B of this part
when supplied with water at the supply
water temperature specified in section
2.3 of appendix E to subpart B of this
part. DOE also tentatively determined
that lowering the set point temperature
for low-temperature water heaters to
their maximum possible delivery
temperature would allow these water
heaters to be tested appropriately and in
a representative manner. As such, DOE
proposed to require low-temperature
water heaters to be tested to their
maximum possible delivery
temperature. 87 FR 1554, 1583 (Jan. 11,
2022).
AET agreed with DOE’s proposal to
add a new definition and product
category for low-temperature water
heaters. (AET, No. 29 at p. 2) EEI
requested more information on the size
of the existing stock, as well as the
current sales volumes of lowtemperature water heaters. (EEI, Jan, 27,
2022 Public Meeting Transcript, No. 27
at pp. 46–47) As with circulating water
heaters, DOE does not currently have
this information available but will
continue to gather this data to the extent
possible.
Rheem commented that the proposed
definition for ‘‘low-temperature water
heater’’ should include water heaters
with less than 10 gallons of storage and
clarify how it is different from other
electric water heaters. Rheem suggested
that the installation and operation (I&O)
manual could be referenced to
determine delivery temperature limits,
but alternatively, manufacturers could
certify supplemental testing instructions
to DOE (i.e., when testing an electric
instantaneous water heater set according
to the I&O manual and cannot meet the
required delivery temperature, the unit
should be tested according to the
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maximum delivery temperature).
(Rheem, No. 31 at p. 3)
In response to the comments from
Rheem, DOE notes that the inability to
deliver water at the specified outlet
water temperatures in appendix E is
independent of the storage volume of
the water heater. Hence, restricting this
product type definition to only those
water heaters that have less than 10
gallons of storage volume may
unintentionally leave larger lowtemperature water heaters without
adequate test provisions in appendix E.
This inability to deliver water at 125 °F
±5 °F—specifically at the appendix E
flow rate—serves as the key
distinguishing factor between lowtemperature water heaters and other
electric instantaneous water heaters.
While the maximum delivery
temperatures may be noted in an I&O
manual, as Rheem suggested, this must
be verified under the test conditions
(most notably the supply water
temperatures) specified in appendix E.
Section 5.2.2 of the amended appendix
E includes instructions for setting the
outlet discharge temperature. Should
the flow rate need to be reduced in
order to meet the outlet temperature
requirements, then the product would
meet the criterion for a low-temperature
water heater.
In this final rule, DOE is adopting a
slightly modified definition for ‘‘lowtemperature water heater,’’ taking into
account the comments provided by
Rheem. Accordingly, DOE is defining
‘‘low-temperature water heater’’ as an
electric instantaneous water heater that
is not a circulating water heater and
cannot deliver water at a temperature
greater than or equal to the set point
temperature specified in section 2.5 of
appendix E when supplied with water
at the supply water temperature
specified in section 2.3 of appendix E at
the flow rate specified in section 5.2.2.1
of appendix E. (DOE is including
language which specifies that the
delivery temperature is that which
results from the appendix E flow rate.)
c. Tabletop Water Heaters
As discussed in the January 2022
NOPR, the definition for ‘‘tabletop water
heater’’ was removed from appendix E
as part of the July 2014 Final Rule but
was inadvertently not added to 10 CFR
430.2 (79 FR 40542, 40567–40568 (July
14, 2014)). 87 FR 1554, 1566 (Jan. 11,
2022). Up until then, ‘‘tabletop water
heater’’ was defined as a water heater in
a rectangular box enclosure designed to
slide into a kitchen countertop space
with typical dimensions of 36 inches
high, 25 inches deep, and 24 inches
wide. 66 FR 4474, 4497 (Jan. 17, 2001).
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In the January 2022 NOPR, after
considering comments on the April
2020 RFI, DOE proposed to add the
definition of tabletop water heater 10
CFR 430.2, as it read prior to being
removed from appendix E. 87 FR 1554,
1556.
In response to the January 2022
NOPR, AET agreed with re-instating the
definition for tabletop water heater at 10
CFR 430.2. (AET, No. 29 at p. 2)
DOE did not receive any other
comment relating to this proposal, so
the Department is re-instating the
definition for ‘‘tabletop water heater’’ at
10 CFR 430.2, as proposed.
d. Solar Water Heaters
In response to an RFI published on
May 21, 2020 (May 2020 RFI), regarding
the energy conservation standards for
consumer water heaters (85 FR 30853),
the Solar Rating & Certification
Corporation (SRCC) recommended that
solar water heating technologies be
considered for inclusion in the energy
conservation standards and test
procedures for consumer water heaters.
SRCC stated that without the
involvement of DOE, the industry
metrics struggle to gain acceptance with
policymakers and consumers. SRCC also
stated that DOE rulemakings to include
solar-equipped water heaters in
regulations would serve to establish a
single performance metric and signal
the legitimacy of solar water heating
technologies. (Docket: EERE–2017–BT–
STD–0019, SRCC, No. 11 at pp. 3–4)
Subsequently, on October 7, 2020,
SRCC published a draft test procedure
titled, ‘‘Solar Uniform Energy Factor
Procedure for Solar Water Heating
Systems’’ (SUEF test method).36 The
draft SRCC test procedure addresses
methods to test different types of solar
water heaters.
In the January 2022 NOPR, DOE
responded to SRCC’s comment on the
May 2020 RFI, by noting that on April
8, 2015, DOE published an energy
conservation standards NOPR (the April
2015 NOPR) addressing definitions for
consumer water heaters (80 FR 18784).
87 FR 1554, 1585 (Jan. 11, 2022). DOE
further noted that the April 2015 NOPR
proposed definitions for ‘‘solar-assisted
fossil fuel storage water heater’’ and
‘‘solar-assisted electric storage water
heater’’ and clarified that water heaters
meeting these definitions are not subject
to the amended energy conservation
standards for consumer water heaters
36 SRCC’s draft Solar Uniform Energy Factor
Procedure for Solar Water Heating Systems is
available at: www.iccsafe.org/wp-content/uploads/
is_stsc/Solar-UEF-Specification-for-Rating-SolarWater-Heating-Systems-20201012.pdf (Last
accessed on July 13, 2022).
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established by the April 2010 final rule.
Id. DOE stated its intention to address
solar water heaters in a separate
rulemaking. Id. In response to the
January 2022 NOPR, SEA commented
that DOE should account for solar water
heaters in its test procedure and energy
conservation standards. (SEA, No. 24 at
p. 1)
In response, DOE notes that ‘‘solar
water heater,’’ as defined in section 5.1
of SRCC’s SUEF test method, include a
solar collector or module that is directly
exposed to solar radiation outdoors and
is often separated from a storage tank
and/or back-up water heater located
indoors. Therefore, appendix E does not
currently accommodate these products,
and an in-depth evaluation of the
modifications to appendix E necessary
to accommodate the testing of these
products is required. Given the lack of
available test data utilizing the SUEF
test method, DOE is not amending the
scope of the appendix E test procedure
in this rulemaking to explicitly include
solar water heaters at this time.
However, DOE will continue to consider
these solar water heater products
further, and depending upon the
conclusions reached, the Department
may address them in a separate future
rulemaking, as appropriate.
B. Updates to Industry Standards
Prior to the effective date of this final
rule, the applicable DOE test procedure
in appendix E referenced the following
industry standards:
• ASHRAE 41.1–1986 (Reaffirmed
2006), Standard Method for
Temperature Measurement (ASHRAE
41.1–1986 (RA 2006)); and
• ASTM D2156–09, (ASTM D2156–
09), Standard Test Method for Smoke
Density in Flue Gases from Burning
Distillate Fuels.
ASHRAE 41.1–1986 (RA 2006) was
superseded by ASHRAE 41.1–2013 on
January 30, 2013 (ASHRAE 41.1–2013).
ASHRAE 41.1–2013 was superseded by
ASHRAE 41.1–2020 on June 30, 2020.
Updates to ASHRAE 41.1 are discussed
in section III.B.1 of this document.
ASTM D2156–09 was reapproved
without modification in 2018 (ASTM
D2156–09 (RA 2018)). In the January
2022 NOPR, DOE proposed to update
appendix E to reference the most recent
version of ASTM D2156 (i.e., ASTM
D2156–09 (RA 2018)). 87 FR 1554, 1567
(Jan. 11, 2022). DOE did not receive any
comments in response to its proposal.
Therefore, DOE is updating the
reference of ASTM D2156–09 to the
most recent industry standard (i.e.,
ASTM D2156–09 (RA 2018)). DOE is
also incorporating by reference ASTM
E97–1987 (W1991) because it is
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necessary to perform procedures within
ASTM D2156–09 and ASTM D2156–09
(RA 2018).37
As discussed previously in this
document, ASHRAE maintains a water
heater test procedure, ANSI/ASHRAE
Standard 118.2, ‘‘Method of Testing for
Rating Residential Water Heaters.’’ The
test procedure specified in ANSI/
ASHRAE 118.2–2006 (RA 2015) is
similar to the DOE test procedure that
was in effect prior to the July 2014 final
rule, although neither the previous DOE
consumer water heater test procedure
nor the version in place prior to this
final rule reference ANSI/ASHRAE
Standard 118.2–2006 (RA 2015). In
March 2019, ASHRAE published the
March 2019 ASHRAE Draft 118.2, the
second public review draft of Board of
Standards Review (BSR) ANSI/ASHRAE
Standard 118.2–2006R, ‘‘Method of
Testing for Rating Residential Water
Heaters and Residential-Duty
Commercial Water Heaters,’’ which DOE
referenced in the April 2020 RFI. 85 FR
21104, 21109–21111 (April 16, 2020). In
April 2021, ASHRAE published
substantive changes to a previous public
review draft 38 of BSR ANSI/ASHRAE
Standard 118.2–2006R, ‘‘Method of
Testing for Rating Residential Water
Heaters and Residential-Duty
Commercial Water Heaters’’ (April 2021
ASHRAE Draft 118.2). The January 2022
NOPR examined these public review
drafts and discussed the differences
between them and the DOE test
procedure. 87 FR 1554, 1567 (Jan. 11,
2022).
On January 24, 2022, ASHRAE
published a revised edition of the 118.2
standard, ‘‘Method of Testing for Rating
Residential Water Heaters and
Residential-Duty Commercial Water
Heaters,’’ ASHRAE 118.2–2022. The
published edition finalized revisions
shown in the March 2019 and April
2021 public review drafts.
In comments responding to the
January 2022 NOPR, Lutz encouraged
DOE to incorporate by reference the
industry test standard ASHRAE 118.2–
2022. Lutz also recommended DOE
review the test procedures in use in
37 Certain methods provided as part of ASTM
E97–1987 (W1991) are directly referenced by ASTM
D2156–09 and ASTM D2156–09 (RA 2018). Copies
of ASTM E97–1987 (W1991) are readily available
from ASTM International, 100 Barr Harbor Drive,
P.O. Box C700, West Conshohocken, PA 19428–
2959 or online at: www.astm.org. (Last accessed on
Sept. 20, 2022.)
38 The April 2021 ASHRAE Draft 118.2 shows
only the proposed substantive changes to the March
2019 ASHRAE Draft 118.2. All sections not
included in the April 2021 ASHRAE Draft 118.2 are
as proposed in the March 2019 ASHRAE Draft 118.2
or have not been changed in a way that their
content affects the results of the test procedure
proposed in the March 2019 ASHRAE Draft 118.2.
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Europe and Japan. (Lutz, No. 35 at p. 1)
BWC supported DOE’s proposal to
incorporate by reference the latest
industry test standards. (BWC, No. 33 at
p. 2)
As discussed previously in this
document, DOE will adopt industry test
standards as DOE test procedures for
covered products and equipment, unless
such methodology would be unduly
burdensome to conduct or would not
produce test results that reflect the
energy efficiency, energy use, water use
(as specified in EPCA) or estimated
operating costs of that equipment during
a representative average use cycle. (10
CFR part 430, subpart C, appendix A,
section 8(c)) In this final rule, DOE is
harmonizing provisions in appendix E
to align with certain updates in
ASHRAE 118.2–2022 rather than
incorporate the entire industry test
standard. DOE has concluded that
certain updates in ASHRAE 118.2–2022
do not meet the EPCA criteria outlined
in this paragraph and has, thus,
determined that those updates should
not be incorporated into the DOE test
procedure at appendix E. DOE’s
assessment of ASHRAE 118.2–2022 is
laid out in detail in section III.B.2 of this
document.
Finally, as discussed in the July 2022
SNOPR, DOE has reviewed NEEA’s
Advanced Water Heating Specifications
in order to assess optional rating
conditions and methods for heat pump
water heaters. This test procedure was
identified by stakeholders in response to
the January 2022 NOPR as becoming a
widely used methodology to provide
alternate ratings for heat pump water
heaters at different climate conditions.
87 FR 42270, 42275–42276 (July 14,
2022). In the January 2022 NOPR, DOE
discussed comments previously
received on the April 2020 RFI
suggesting that DOE explore the usage of
NEEA’s Advanced Water Heating
Specification—which was at version 7.0
at the time—for voluntary climatespecific efficiency representations of
heat pump water heaters. 87 FR 1554,
1580 (Jan. 11, 2022). In response to
those comments, DOE stated that it did
not have data to indicate what
conditions would be representative for
regional representations, and, thus, DOE
tentatively determined not to allow
optional representations of additional
efficiency ratings at test conditions
other than those found in the DOE test
procedure (which are representative of
the Nation as a whole), such as those
made in accordance with NEEA’s
Advanced Water Heating Specification.
Id. However, as discussed in the July
2022 SNOPR, DOE has re-evaluated the
benefits to consumers provided by
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optional representations. 87 FR 42270,
42275–42277 (July 14, 2022). In this
final rule, DOE is including optional test
conditions for heat pump water heaters
aligning with version 8.0 (the latest
version) of NEEA’s Advanced Water
Heating Specification. This matter is
discussed in further detail in section
III.C.7 of this document.
1. ASHRAE 41.1–2020
As stated previously, ASHRAE 41.1–
1986 (RA 2006) was superseded by
ASHRAE 41.1–2013, and ASHRAE
41.1–2013 was superseded by ASHRAE
41.1–2020. ASHRAE 41.1–2013
removed the aspirated wet-bulb
psychrometer descriptions and stated
they would be included in the next
revision to ASHRAE 41.6, ‘‘Standard
Method for Humidity Measurement.’’
ASHRAE 41.6 was updated on July 3,
2014, and included the aspirated wetbulb psychrometer descriptions that
were removed in ASHRAE 41.1–2013.
ASHRAE 41.1–2013 also added
uncertainty analysis for temperature
measurements, information for
thermistor-type devices, descriptions for
thermopiles, and reorganized the
standard to be consistent with other
ASHRAE standards. ASHRAE 41.1–
2020 added conditional steady-state test
criteria and further updated the
standard to meet ASHRAE’s mandatory
language requirements.
As discussed in the January 2022
NOPR, section 3.2.1 of appendix E
requires that temperature measurements
be made in accordance with ASHRAE
41.1–1986 (RA 2006), and section 3.2.2
of appendix E provides accuracy and
precision requirements for air dry-bulb,
air wet-bulb, inlet and outlet water, and
storage tank temperatures. Sections
5.2.2.1 and 5.3.2 of appendix E
effectively require steady-state operation
in which the flow-activated water heater
is operating at the maximum input rate,
is supplied with water at a temperature
of 58 °F ±2 °F, and delivers water at a
temperature of 125 °F ±5 °F. 87 FR 1554,
1567 (Jan. 11, 2022).
In the development of this final rule,
DOE reviewed ASHRAE 41.1–1986 (RA
22006), ASHRAE 41.1–2013, and
ASHRAE 41.1–2020 and found that the
sections most relevant to appendix E are
the temperature measurement sections
(i.e., sections 5 through 11 of ASHRAE
41.1–1986 (RA 2006), section 7 of
ASHRAE 41.1–2013, and section 7 of
ASHRAE 41.1–2020) 39 and the steadystate test criteria added in ASHRAE
41.1–2020. The information in the
39 Sections 5 through 11 of ASHRAE 41.1–1986
(RA 2006) were combined into section 7 of
ASHRAE 41.1–2013.
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temperature measurement sections of
the examined three versions of ASHRAE
41.1 does not vary significantly. The
additional steady-state test criteria of
ASHRAE 41.1–2020 varies significantly
from and is more stringent than 40 the
criteria specified in sections 5.2.2.1 and
5.3.2 of appendix E; however, the
appendix E criteria supersede those in
ASHRAE 41.1–2020.
In the January 2022 NOPR, DOE
tentatively determined that updating the
reference of ASHRAE 41.1–1986 (RA
2006) to the most recent version of the
industry standard (i.e., ASHRAE 41.1–
2020) would not have a significant effect
on the test results, as the content of the
relevant sections of the ASHRAE 41.1
standards have not changed
significantly and the new content
published in ASHRAE 41.1–2020 is
superseded by appendix E. As such,
DOE proposed to update the reference of
ASHRAE 41.1–1986 (RA 2006) to
ASHRAE 41.1–2020. ASHRAE 41.1–
2020 references ASHRAE 41.6–2014 and
requires its use when measuring the
wet-bulb temperature. The wet-bulb
temperature is required when testing
heat pump water heaters to appendix E,
and, therefore, DOE also proposed to
incorporate by reference ASHRAE 41.6–
2014. 87 FR 1554, 1567–1568 (Jan. 11,
2022).
DOE did not receive any comments in
response to its proposals to incorporate
by reference ASHRAE 41.1.–2020 and
ASHRAE 41.6–2014; therefore, DOE is
incorporating by reference both
standards in this final rule for the
reasons previously stated.
2. ASHRAE 118.2–2022
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ASHRAE 118.2–2022, published on
January 24, 2022 and approved by ANSI
on March 1, 2022, supersedes ASHRAE
118.2–2006. The foreword to ASHRAE
118.2–2022 states that it was derived
from the DOE appendix E test procedure
but also has several substantive changes.
Specifically, it notes that a major change
was to move the conditions of the test
(air temperature, humidity, inlet and
outlet water temperatures) and draw
patterns to an Informative Appendix A,
‘‘U.S. Values for Test Variables,’’
indicating that this test standard has
been revised such that it can easily be
applied with other test conditions and
draw patterns. Additionally, the
40 Section 5.5.3 of ASHRAE 41.1–2020 would be
used to determine steady-state operation within
sections 5.2.2.1 and 5.3.2 of appendix E. Using this
criteria, a flow-activated water heater delivering
water between 120 °F and 121 °F, which is within
the current delivery temperature range of 125 °F ±
5 °F, would not be considered in steady-state due
to the difference in temperature between the
average of the sample and the set point temperature.
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foreword states that other changes
include clarifying the timing of the
standby period, clarifying the end of the
recovery period, specifying that the
density of water used in calculations be
measured at the outlet, and adjusting
the FHR flow rate for smaller tanks and
defining a draw time limit if the water
heater can keep up with the FHR flow
rate. The following subsections of this
final rule discuss the substantial
differences between the updated
ASHRAE 118.2–2022 test standard and
DOE’s existing appendix E test
procedure. Based on a review of its own
test data and stakeholder feedback, the
Department is not adopting every
update in ASHRAE 118.2–2022 into the
amended appendix E test procedure
promulgated by this final rule. DOE has
provided discussion of the amendments
being made to harmonize with ASHRAE
118.2–2022 in section III.B.2.b of this
document, whereas other updates in
ASHRAE 118.2–2022 not being adopted
are discussed in section III.B.2.c of this
document.
AET generally supported DOE’s
proposal to adopt most aspects of
ASHRAE 118.2 but noted that the
definition of ‘‘UEF’’ in ASHRAE 118.2
is different from the definition of that
term used by DOE. AET noted that a
UEF rating per ASHRAE Standard 118.2
would not be comparable to a UEF
rating per DOE’s test procedure due to
differences in test conditions. (AET, No.
29 at pp. 6–7) DOE agrees that there
could be differences between the UEF
test result from ASHRAE 118.2–2022
and the amended appendix E test
procedure from this final rule. Where
differences between these test
procedures exist, the requirements at 10
CFR 430.23 and appendix E control. As
such, manufacturers must ensure that
any representations of ‘‘UEF’’ are made
in accordance with the applicable
version of the DOE test procedure.
a. Scope
Section 2 of ASHRAE 118.2–2022
states that the industry test standard
applies to water heaters designed to be
capable of providing outlet water at a
controlled temperature of at least the
nominal outlet water temperature under
the conditions specified in the standard.
As discussed in section III.A.4.b of this
final rule, the January 2022 NOPR
proposed to expand the scope of the
DOE test procedure to include lowtemperature water heaters. 87 FR 1554,
1582–1583 (Jan. 11, 2022). As such, the
scope of ASHRAE 118.2–2022 is
narrower than the test procedure
proposed in DOE’s January 2022 NOPR
and July 2022 SNOPR because it
explicitly excludes low-temperature
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40425
water heaters. In order to include lowtemperature water heaters within the
scope of the amended appendix E test
procedure, DOE is including testing
provisions which are not in ASHRAE
118.2–2022 to allow for the testing of
low-temperature water heaters. These
test methods are discussed in section
III.E.3 of this final rule.
Additionally, the scope of ASHRAE
118.2–2022 differs significantly from the
scope of products covered under the
EPCA definition for consumer ‘‘water
heater’’ and DOE’s definition for
‘‘residential-duty commercial water
heater.’’ For example, section 2 of
ASHRAE 118.2–2022 limits the storage
volume for storage-type water heaters to
120 gallons or less and limits the
maximum delivery temperature to
180 °F (82 °C), whereas EPCA does not
place limits on storage volume or
maximum delivery temperature for
consumer water heaters. (42 U.S.C.
6291(27); 42 U.S.C. 6311(12)(A)–(B)))
The scope of electric instantaneous
water heaters covered by ASHRAE
118.2–2022 equates to the limit for
residential-duty commercial electric
instantaneous water heaters; however,
section 2.2 of ASHRAE 118.2–2022 does
not specify any limits on storage
volume, and as a result, it covers certain
commercial electric instantaneous water
heaters—whereas the currently
applicable appendix E test procedure
does not. Section 2.1 of ASHRAE 118.2–
2022 has a definition for ‘‘electric heatpump storage water heater’’ which
explicitly limits the nameplate input
rating to 12 kilowatts or less, which, as
discussed in section III.A.2.a of this
final rule, does not correspond to the
statutory limit for heat pump-type units
and would include commercial heat
pump water heaters (which are outside
of the scope of the appendix E test
procedure). Finally, section 2.4 of
ASHRAE 118.2–2022 limits gas-fired
heat pump storage water heaters to
nameplate input ratings no greater than
20,000 Btu/h, which is significantly
lower than the statutory limit of 75,000
Btu/h (see 42 U.S.C. 6291(27)(A) and the
discussion in section III.A.2.b of this
document).
In the January 2022 NOPR, DOE
evaluated feedback from commenters
indicating that most aspects of the test
methods in ASHRAE 118.2–2022 41
were still applicable outside of its
formal scope of coverage. 87 FR 1554,
1568 (Jan. 11, 2022). In the January 2022
41 ASHRAE 118.2–2022 was published on January
24, 2022, which was after the January 2022 NOPR
was published in the Federal Register on January
11, 2022; thus, the NOPR only discusses public
review drafts of ASHRAE 118.2–2022 which were
available at the time.
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NOPR, DOE stated that it has found
through testing that models with rated
storage volumes above 120 gallons or
that can deliver water above 180 °F can
be tested to DOE’s appendix E test
procedure, and, given the similarities
between the currently applicable DOE
test procedure and ASHRAE 118.2–
2022, DOE tentatively determined that
such models could also be tested using
the methods in the ASHRAE test
standard. Id. DOE did not receive any
comments in response to this tentative
conclusion in the January 2022 NOPR.
Therefore, in evaluating the provisions
within ASHRAE 118.2–2022, DOE has
determined that its test methods remain
applicable to all consumer water heaters
and residential-duty commercial water
heaters within the scope of appendix E
(with the exception of low-temperature
water heaters). As proposed in the
January 2022 NOPR, this final rule
makes several amendments to appendix
E to harmonize with new provisions in
ASHRAE 118.2–2022. Additionally,
DOE determined that methods specified
in annex B of ASHRAE 118.2 were
applicable to the associated test
procedures of this rulemaking, and,
therefore, the Department has
incorporated by reference ASHRAE
118.2–2022 for use in appendix E, with
annex B being the directly applicable
provision.
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b. Provisions in ASHRAE 118.2–2022
Being Addressed by DOE
Thermal Break
ASHRAE 118.2–2022 specifies the use
of a ‘‘thermal break’’ in the test set-ups
shown for free-standing water heaters
and water heaters supplied with a
countertop enclosure (see Figures 1, 2,
3, 6, 7, 8, and 9 of ASHRAE 118.2–
2022). A thermal break is optional in the
ASHRAE 118.2–2022 test set-ups shown
for wall-mounted water heaters (see
Figures 4 and 5 of ASHRAE 118.2–
2022).
ASHRAE 118.2–2022 defines a
‘‘thermal break’’ in section 3 as a nipple
made of material that has thermal
insulation properties (e.g. plastics) to
insulate the bypass loop from the inlet
piping. It should be able to withstand a
pressure of 150 psi (1.034 MPa), and a
temperature greater than the maximum
temperature the water heater is designed
to produce. A thermal break is added to
the test set-up to prevent heat from
traveling up the inlet piping into a
bypass line, if one is utilized. (ASHRAE
118.2–2022 requires a bypass line to be
installed, whereas the existing appendix
E test procedure does not.) When
purging the inlet piping before a draw,
any heat that is transferred from the
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water heater through the inlet piping to
the bypass line section would be lost, as
the bypass line is replenished with cold
supply water. The thermal break helps
to prevent this heat loss.
In this rulemaking, DOE has sought
feedback from stakeholders in the April
2020 RFI as to whether a thermal break
should be required in the DOE test
procedure regardless of whether a
bypass line is used, and additionally,
whether DOE should adopt a definition
for this set-up component. 85 FR 21104,
21110 (April 16, 2020). The January
2022 NOPR discussed the mixed
comments received on this topic. In
summary, three commenters stated that
a thermal break should be included in
the test set-up regardless of whether
there is a bypass or purge line; however,
three others (including a testing
standards organization, CSA Group)
stated that a thermal break is not needed
if no bypass or purge loop is present.
Several commenters indicated that a
standardized definition for a ‘‘thermal
break’’ would be beneficial for
repeatability of the test procedure. 87
FR 1554, 1569 (Jan. 11, 2022).
In the January 2022 NOPR, DOE
explained that a bypass line is a method
that test laboratories use to ensure inlet
water temperatures are within the
bounds of the test procedure (i.e.,
within 58 °F ±2 °F by the first
measurement of the draw), but its
inclusion in the test set-up can create a
condition whereby a constant low
temperature can remove energy from the
water heater at a higher rate than would
be removed in the field. Because a
bypass line is not the only approach to
maintaining inlet conditions, DOE had
tentatively determined that requiring a
thermal break (and providing a
definition for this component) would
not be necessary. Id.
BWC responded by indicating that it
is not aware of any manufacturer or test
laboratory omitting the use of a thermal
break, and, therefore, DOE should adopt
a definition for ‘‘thermal break’’ to
ensure consistent results from
laboratory to laboratory. The commenter
recommended that a thermal break
should be defined as ‘‘a plastic and
thermally non-conductive material that
can withstand a minimum temperature
of 150 °F.’’ BWC also stated that its
testing indicated that when a bypass
line (also known as a ‘‘purge loop’’) is
used, all temperatures more consistently
met the tolerance criteria in appendix E;
furthermore, test results were more
often out of tolerance when a bypass
line was not used. BWC argued that as
a result, use of a bypass line will remain
common practice, and as such, thermal
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breaks will also continue to be used.
(BWC, No. 33 at p. 3)
DOE has considered the comments
received on this topic throughout this
rulemaking, and, although DOE
maintains that a thermal break would
not be needed in all set-up cases, the
Department has concluded that there is
overwhelming support for establishing a
standardized definition for ‘‘thermal
break.’’ In order to address concerns
regarding the repeatability of the test
procedure (i.e., various facilities
maintaining a consistent set-up
approach), DOE is adopting a definition
for this component consistent with that
in section 3 of ASHRAE 118.2–2022, but
with minor modification. Specifically,
DOE is defining ‘‘thermal break’’ as ‘‘a
thermally non-conductive material that
can withstand a pressure of 150 psi
(1.034 MPa) at a temperature greater
than the maximum temperature the
water heater is designed to produce and
is utilized to insulate a bypass loop, if
one is used in the test set-up, from the
inlet piping.’’ However, DOE is not
requiring the use of a bypass loop or a
thermal break in this final rule. DOE
reasons that providing a definition for a
thermal break will improve consistency
in test set-ups when the testing agency
opts to use a bypass loop with a thermal
break.
FHR Test Flow Rates
Section 7.3.3.1 of ASHRAE 118.2–
2022 indicates that the flow rate for
non-flow-activated water heaters with
rated storage volumes less than 20
gallons would be 1.5 ± 0.25 gallons per
minute (gpm) (5.7 ± 0.95 liters (L)/
minute (min)) when conducting the
FHR test. Section 5.3.3, ‘‘First-Hour
Rating Test,’’ of appendix E requires
that water heaters with a storage volume
less than 20 gallons be tested at 1.0 ±
0.25 gpm (3.8 ± 0.95 L/min). These flow
rates are lower than the 3.0 ± 0.25 gpm
(11.4 ± 0.95 L/min) required for water
heaters with rated storage volumes
greater than or equal to 20 gallons.
Water heaters with low rated storage
volumes (less than 20 gallons) and high
input rates can potentially operate
indefinitely (i.e., instantaneously) at
even the 3.0 ± 0.25 gpm (11.4 ± 0.95 L/
min) flow rate. Therefore, when such
products are tested as currently required
by appendix E, the measured FHR is
near the maximum possible value of 60
gallons (227 L) 42 and, as a result, these
42 At 1.0 ±0.25 gallons per minute during the 60minute first-hour rating test, the maximum possible
delivery capacity is 1.0 gallon per minute × 60
minutes = 60 gallons. At 1.5 ± 0.25 gallons per
minute during the 60-minute first-hour rating test,
the maximum possible delivery capacity is 1.5
gallon per minute × 60 minutes = 90 gallons.
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products would be required to use the
medium draw pattern according to
Table I of appendix E. However, as
discussed in the January 2022 NOPR,
these models could be used in
applications similar to water heaters
that are required to test using the high
draw pattern, and the existing method
of testing these products may not best
represent how they are used in the field.
Instead, DOE finds that a flow rate of 1.5
± 0.25 gpm (5.7 ± 0.95 L/min)—as
introduced in ASHRAE 118.2–2022—
would be sufficient to allow these
products to be tested and rated in the
high draw pattern. 87 FR 1554, 1569–
1570 (Jan. 11, 2022).
In this rulemaking, DOE has sought
information from commenters regarding
the flow rate for the FHR test of nonflow-activated water heaters with rated
storage volumes less than 20 gallons.
DOE has also participated in the public
review of ASHRAE 118.2 prior to the
2022 edition being released, leading up
to the establishment of the 1.5 ± 0.25
gpm (5.7 ± 0.95 L/min) flow rate criteria
for these products during the FHR test.
DOE also performed testing on three
electric storage water heaters less than
20 gallons to both the then currently
applicable appendix E and ASHRAE
118.2–2022 flow rates and provided
these test data in the January 2022
NOPR. The results indicated that
changing the flow rate during the FHR
test for water heaters with a rated
storage volume less than 20 gallons from
1.0 ± 0.25 gpm (3.8 ± 0.95L/min) to 1.5
± 0.25 gpm (5.7 ± 0.95 L/min) would
have a relatively minimal impact on the
FHR for water heaters with low input
rates. For models with high input rates,
the change in flow rate could
significantly increase the FHR and
result in some models being tested and
rated for UEF using a higher draw
pattern, which would provide ratings
that are more representative of their
actual use. Therefore, DOE proposed to
adopt the higher flow rate of 1.5 ± 0.25
gpm (5.7 ± 0.95 L/min) for the FHR test
of non-flow-activated water heaters with
rated storage volumes less than 20
gallons. 87 FR 1554, 1570 (Jan. 11,
2022).
In response, AHRI indicated that the
revised flow rate of 1.5 gpm may not be
appropriate for models as small as 2
gallons, for which the proposed change
could yield unrepresentative results for
FHR. (AHRI, No. 40 at p. 4) AHRI also
raised concerns about the accuracy of
flow rates for smaller capacity water
heaters. (AHRI, Jan. 27, 2022 Public
Meeting Transcript, No. 27 at p. 41)
Rheem generally supported DOE’s
proposal to align with ASHRAE 118.2–
2022 on this issue. However, Rheem
pointed out that the test data provided
in the NOPR reflected consumer water
heaters in only the very small draw
pattern, so Rheem requested DOE to
provide further test data and also to
conduct testing on products near the
division between the very small and low
draw patterns. Rheem stated that a
change in draw pattern will affect the
40427
UEF rating and will need to be taken
into account. (Rheem, No. 31 at p. 2)
In response to the concerns raised by
AHRI, DOE notes that its test data
presented in the January 2022 NOPR
were taken from samples in the very
small draw pattern (see 87 FR 1554,
1570 (Jan. 11, 2022)). DOE has
additionally provided the storage
volumes of the products which were
tested in Table III.1 of this final rule.
The samples were all approximately 2
gallons in storage volume, and the 1.5
gpm flow rate was found to be
sufficiently representative for these
products (the absolute value of the
largest percent difference was less than
5 percent). Additionally, as stated in the
January 2022 NOPR, the increase in
flow rate did not cause any of these
products to move from the very small
draw pattern to the low draw pattern,
which resolves a chief concern
regarding the representativeness of the
FHR results. Id. In response to Rheem’s
requests for additional data, DOE was
not able to identify non-flow-activated
water heaters less than 20 gallons closer
to 18 gallons of FHR—the division
between the very small and low draw
patterns—in order to perform testing on
such products. However, while the net
average change may approximately be a
2-percent increase in FHR rating, DOE
has determined that the increased flow
rate will allow products to be rated in
more representative draw patterns, as
discussed earlier in this section.
TABLE III.1—AVERAGE FIRST-HOUR RATING BASED ON A FLOW RATE OF 1.0 GPM AND 1.5 GPM
Unit No.
Measured
storage
volume,
gallons
Average FHR * at 1.0 gpm (3.8 L/
min), gallons
Average FHR * at 1.5 gpm (5.7 L/
min), gallons
1 ......................................................
2 ......................................................
3 ......................................................
Net Average ............................
2.4
2.4
1.8
........................
7.3 (Very Small) .............................
6.4 (Very Small) .............................
6.9 (Very Small) .............................
........................................................
7.5 (Very Small) .............................
6.2 (Very Small) .............................
7.2 (Very Small) .............................
+2.0.
Change
%
+3.4
-2.2
+4.7
* FHR results are rounded to the nearest 0.1 gallon and reflect the arithmetic mean of four trials per water heater.
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In this final rule, DOE is amending
section 5.3.3.1 of the appendix E test
procedure to require a flow rate of 1.5
± 0.25 gpm (5.7 ± 0.95 L/min) when
conducting the FHR test on non-flowactivated water heaters with rated
storage volumes less than 20 gallons.
24-Hour Simulated-Use Test First
Recovery Period
The first recovery period of the 24hour simulated-use test is used in
section 8.3.2 of ASHRAE 118.2–2022
and section 6.3.2 of appendix E to
calculate recovery efficiency. Section
8.3.2 of ASHRAE 118.2–2022 specifies
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that, when the first recovery of the 24hour simulated-use test ends during a
draw, the first recovery period extends
until the end of that draw, whereas
DOE’s test procedure does not explicitly
address how to calculate recovery
efficiency if the first recovery period
ends during a draw.
A ‘‘recovery period’’ is defined in
section 1 of appendix E as ‘‘the time
when the main burner of a storage water
heater is raising the temperature of the
stored water.’’ Each of the parameters in
the current recovery efficiency equation
in section 6.3.2 of appendix E is
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recorded from the ‘‘beginning of the test
to the end of the first recovery period
following the first draw.’’ The currently
applicable appendix E test procedure
does not explicitly state whether values
are recorded at the end of the recovery
period that ends after the initiation of
the first draw, or at the end of a recovery
period that occurs after the end of the
first draw.
In the January 2022 NOPR, DOE noted
that the situation in which a recovery
ends during a draw likely occurs during
draws with a low enough flow rate that
the water heater can heat water more
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quickly than the draw is removing. 87
FR 1554, 1574 (Jan. 11, 2022). DOE also
explained that the energy used for the
recovery efficiency calculation includes
energy used to heat water and auxiliary
energy; therefore, the energy associated
with the first recovery period should
represent the entire draw to capture all
energy use. Id.
On January 31, 2020, DOE published
in the Federal Register a Notice of
Decision and Order 43 (Decision and
Order) by which a test procedure waiver
for certain basic models was granted to
address the issue of a second recovery
initiating during the draw during which
the first recovery ended. 85 FR 5648.
The Decision and Order prescribes an
alternate test procedure that extends the
first recovery period to include both the
first and second recoveries. Id. at 85 FR
5652. In the context of the Decision and
Order, DOE determined that the
consideration of delivered water mass
and inlet and outlet temperatures until
the end of the draw is appropriately
representative, and, therefore, the entire
energy used from both recoveries is
included. Id. at 85 FR 5651–5652.
In the January 2022 NOPR, after
considering comments received in
response to the April 2020 RFI, DOE
proposed to establish a new provision
that states that when the first recovery
ends during a draw, the first recovery
period is extended to the end of the
draw and the mean tank temperature
measured immediately after cut-out is
used as the maximum mean tank
temperature value in the recovery
efficiency calculation. 87 FR 1554, 1574
(Jan. 11, 2022). In addition, DOE
proposed to update the recovery
efficiency equation to specify
accounting for the mass of water drawn
for all draws initiated during the
recovery period. DOE noted that such a
change would be consistent with the
published Notice of Decision and Order
and was supported by commenters. Id.
In response, BWC stated the proposed
updates to the overall test procedure
provide a more accurate calculation of
recovery efficiency and eliminate
situations where products would be
disadvantaged for completing their
recovery in the middle of a draw,
thereby providing a more representative
measurement of a product’s overall
energy efficiency. (BWC, No. 33 at pp.
5–6)
DOE did not receive any other
comments in response to these
proposals. As such, DOE is amending
43 Notice of Decision and Order in response to
BWC petition for waiver is available at:
www.regulations.gov/document?D=EERE-2019-BTWAV-0020-0008.
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appendix E to adopt the proposals from
the January 2022 NOPR, which are
consistent with the alternate test
procedure in the Decision and Order
and in ASHRAE 118.2–2022.
24-Hour Simulated-Use Test Final Hour
Although not stated explicitly in
section 5.4.2 of the currently applicable
appendix E, in the case that the standby
period is between the first and second
draw clusters, power to the main
burner, heating element, or compressor
is disabled during the last hour of the
24-hour simulated-use test. In the case
that the standby period is after the last
draw of the 24-hour simulated-use test,
power to the main burner, heating
element, or compressor is not disabled.
Section 5.4.2 of the currently applicable
appendix E states that during the last
hour of the 24-hour simulated-use test,
power to the main burner, heating
element, or compressor shall be
disabled; at 24 hours, record the reading
given by the gas meter, oil meter, and/
or the electrical energy meter as
appropriate; and determine the fossil
fuel and/or electrical energy consumed
during the entire 24-hour simulated-use
test and designate the quantity as Q.
Section 5.4.2 of the currently applicable
appendix E also provides that in the
case that the standby period is after the
last draw of the 24-hour simulated-use
test, an 8-hour standby period is
required, and this period may extend
past hour 24. The procedures for the
standby period after the last draw of the
24-hour simulated-use test allow for a
recovery to occur at the end of the 8hour standby period, which indicates
that the power to the main burner,
heating element, or compressor is not
disabled. DOE’s procedure, as
described, may result in some
confusion. Further, the method of
determining the total energy use during
the 24-hour simulated-use test, Q, and
total test time are not explicitly stated
for when a standby period occurs after
the last draw of the 24-hour simulateduse test. As discussed in the following
paragraphs, DOE is amending the
procedures for the last hour of the 24hour simulated-use test, consistent with
its proposals in the January 2022 NOPR,
to explain how to end the test for both
standby period scenarios, and this
amendment aligns with the updated
approach in ASHRAE 118.2–2022.
In ASHRAE 118.2–2022, power is not
disabled when the standby period
occurs after the last draw of the test.
However, if a recovery occurs between
an elapsed time of 23 hours following
the start of the test (hour 23) and 24
hours following the start of the test
(hour 24), the following alternate
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approach is applied to determine the
energy consumed during the 24-hour
simulated-use test: The time, total
energy used, and mean tank temperature
are recorded at 1 minute prior to the
start of the recovery occurring between
hour 23 and hour 24, along with the
average ambient temperature from 1
minute prior to the start of the recovery
occurring between hour 23 and hour 24
to hour 24 of the 24-hour simulated-use
test. These values are used to determine
the total energy used by the water heater
during the 24-hour simulated-use test.
This alternate calculation combines the
total energy used 1 minute prior to the
start of the recovery occurring between
hours 23 and 24 and the standby loss
experienced by the tank during the time
between the minute prior to the
recovery start and hour 24. This
provision in section 7.4.3.2 of ASHRAE
118.2–2022 does not require the water
heater to be de-energized during the
standby period. Disabling power to the
water heater is typically a manual
operation that requires the presence of
a technician. In cases where the
technician does not disable power at the
correct time, a retest of the 24-hour
simulated-use test may be necessary. To
the extent this provision would
eliminate the need to ensure that a unit
is switched off for the last hour of the
24-hour simulated-use test, it could
reduce test burden.
In the January 2022 NOPR, after
considering comments on the April
2020 RFI, DOE tentatively concluded
that further evaluation of the alternate
procedure presented in the March 2019
ASHRAE Draft 118.2 and April 2021
ASHRAE Draft 118.2 should be
conducted before a determination is
made on whether DOE should adopt
such changes. However, DOE also
tentatively determined that the
procedure for the last hour of the 24hour simulated-use test would benefit
from further, more explicit instruction,
and, thus, DOE proposed to explicitly
state how to end the test depending on
whether the standby period is between
draw clusters 1 and 2 or after the last
draw of the test. 87 FR 1554, 1575 (Jan.
11, 2022).
No comments or data were received
on this topic in response to the January
2022 NOPR or July 2022 SNOPR.
As such and for the reasons
previously stated, DOE is finalizing its
proposal from the January 2022 NOPR
to clarify how to end the test depending
on when the standby period occurs.
DOE will continue to evaluate the
impacts of fully adopting the ASHRAE
118.2–2022 method and may consider
that in a future test procedure
rulemaking for the subject water heaters.
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As discussed in section III.E.4 of this
document, DOE is dividing section 5.4.2
of appendix E into two sections: section
5.4.2.1, ‘‘Water Heaters that Can Have
Internal Storage Tank Temperature
Measured Directly,’’ and section 5.4.2.2,
‘‘Water Heaters that Cannot Have
Internal Storage Tank Temperature
Measured Directly.’’ The new section
5.4.2.1 of appendix E provides specific
direction on the measurements to be
taken if the standby period occurs at the
end of the first recovery period after the
last draw of the 24-hour simulated-use
test. These revised instructions for the
final hour of the 24-hour simulated-use
test also no longer require disabling the
water heater for the standby mode, a
change which harmonizes with the
procedure in ASHRAE 118.2–2022. DOE
has determined that these provisions are
appropriate only for water heaters that
can have internal storage tank
temperatures measured directly,
because these steps require recording
the mean tank temperature at various
points during the final hour. For water
heaters that cannot have internal storage
tank temperatures measured directly,
DOE is adopting an alternative method
entirely (discussed in section III.E.7 of
this document) which requires a
standby period after the final draw and
temperature measurements made via
estimation.
c. Other Updates
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Inlet Water Temperature Measurement
Location
In its review of the ASHRAE 118.2–
2022 set-up figures, DOE determined
that the placement of the inlet water
temperature measurement probe differs
between ASHRAE 118.2–2022 and the
currently applicable appendix E. In
ASHRAE 118.2–2022, the inlet water
temperature is always measured on the
upstream side of the heat trap formed by
the U-bend in the required piping,
whereas the figures in appendix E vary
this location (i.e., either on the upstream
side or on the downstream side of the
U-bend) depending on the type of water
heater being tested.
DOE requested information about the
potential impact of this measurement
location on energy efficiency results in
the January 2022 NOPR. 87 FR 1554,
1569 (Jan. 11, 2022).
On this topic, BWC stated there are
inconsistencies in the placement of inlet
thermocouples in the set-up figures
currently shown in appendix E. BWC
suggested adopting the figures in
ASHRAE Standard 118.2, as they are
representative of most set-ups and
illustrate placement of the inlet
thermocouples on the upstream side of
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the U-bend in all instances. BWC also
more generally urged DOE to adopt the
water heater test set-up figures adopted
in ASHRAE 118.2–2022, stating that it
is not aware of any testing laboratory
that does not utilize the set-ups
depicted in these figures. (BWC, No. 33
at pp. 2–3) (DOE understands the
‘‘inconsistencies’’ mentioned by BWC as
referring to the differences in
temperature probe placement for
different types of water heaters, as
mentioned at the beginning of this
subsection.)
AET indicated that there may be
problems with the location and
orientation of the bypass (purge) line
connection in the ASHRAE 118.2–2022
test set-ups when testing small water
heaters (i.e., electric instantaneous
water heaters). The commenter claimed
that without a bypass line installed at
the water inlet, it is not possible to meet
the test conditions and tolerances for
the inlet water temperature during test
draws when the measurement location
is as specified in the current appendix
E test procedure. AET explained that the
location of the bypass line combined
with the rest of the piping configuration
for measuring inlet water temperature
can induce a small amount of flow in
the piping near the inlet to the water
heater, even when a draw is not being
conducted and there is no flow through
the water heater. According to AET,
flow-activated water heaters with
especially sensitive flow sensors could
initiate heating upon sensing this ‘‘false
flow,’’ and this would in turn cause the
energy consumption under test to
increase in an unrepresentative manner.
AET provided a detailed description of
this phenomenon in its public comment
and stated that its claims were
substantiated by review of recent test
data, though these data were not
provided to DOE. AET suggested that
one potential solution to the identified
problem could be to move the
connection point of the purge line and
the inlet measurement location further
from the water heater. In addition, AET
suggested adjusting the various pipe Tjunctions and their orientations such
that the momentum of a cold-water
purge will be directed horizontally away
from the pipe direction going to the
water heater and not induce a false flow,
with the commenter opining that this
change could be implemented for all
types of water heaters. (AET, No. 29 at
pp. 6–9)
As discussed in the January 2022
NOPR, maintaining the same inlet water
temperature measurement location for
all water heater types ((i.e., harmonizing
with ASHRAE 118.2–2022)) would
simplify the test set-up as compared to
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the requirements of the currently
applicable appendix E. However, DOE
did not have sufficient information at
the time to propose such harmonization.
87 FR 1554, 1568–1569 (Jan. 11, 2022).
In the January 2022 NOPR, DOE noted
that use of a bypass loop is not the only
possible test set-up for meeting the test
conditions within appendix E. 87 FR
1554, 1569 (Jan. 11, 2022). However,
based on the comment from BWC, DOE
understands that many test facilities do
use a bypass loop as a solution to having
to stabilize the inlet water conditions.
After considering the comments from
AET and BWC, DOE has determined
that laboratories are likely to continue to
use bypass lines regardless of the
placement of the inlet water
temperature measurement, because a
bypass line is simple to install and
relatively low-cost. If this occurs, then
there is a risk that UEF ratings for
certain flow-activated water heaters
with highly sensitive sensors may be
lower due to the additional energy
consumption of the water heater when
a false flow is sensed. DOE is not
incorporating the updates found in the
ASHRAE 118.2–2022 figures. Instead,
DOE is maintaining the current set-up
directions for inlet water temperature
measurement in appendix E and, which
will allow for the continued use of a
bypass line when necessary and
appropriate. Regarding AET’s concerns
about the location of the bypass loop for
certain electric instantaneous water
heaters, DOE notes that it has not
observed the issue in any of its testing.
Further, DOE is not adopting the figures
in ASHRAE 118.2–2022, so, therefore,
the Department is not specifying the
location of the bypass loop in its test
set-up. Accordingly, during testing,
there will be sufficient flexibility to
locate the bypass line, when necessary,
in a location that results in
representative operation and
performance of the unit under test.
FHR Test Initiation Criteria
ASHRAE 118.2–2022 includes
additional criteria defining the start of
the FHR test as compared to DOE’s test
procedure at appendix E. These
differences are briefly explained in the
following paragraphs.
Section 5.3.3.3 of the currently
applicable appendix E states that prior
to the start of the FHR test, if the water
heater is not operating (i.e., heating
water), initiate a draw until cut-in 44
44 ‘‘Cut-in’’ is defined in section 1 of appendix E
as ‘‘the time when or water temperature at which
a water heater control or thermostat acts to increase
the energy or fuel input to the heating elements,
compressor, or burner.’’
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(i.e., when the water heater begins
heating water). The draw is then
terminated any time after cut-in, and the
water heater is operated until cut-out.45
Once the maximum mean tank
temperature is observed after cut-out,
the initial draw of the FHR test begins.
Section 7.3.3.3 of ASHRAE 118.2–
2022 specifies that the draw preceding
the initial draw of the FHR test must
proceed until the outlet temperature
drops 15 °F below the maximum outlet
temperature observed, or until a draw
time limit 46 is reached. If the draw time
limit is reached before the outlet
temperature drops 15 °F below the
maximum outlet temperature observed,
then the main heating source of the
water heater is shut off, and the draw is
continued until the outlet temperature
has dropped 15 °F below the maximum
outlet temperature. Requiring the outlet
temperature to drop 15 °F below the
maximum outlet temperature may
provide a more consistent starting
condition for the FHR test compared to
the pre-conditioning method specified
in the currently applicable DOE test
procedure because draws of varying
lengths can create different internal tank
temperature profiles.
Thus, in the January 2022 NOPR, DOE
tentatively determined that the
additional requirement to tie the length
of the initial draw to a specific outlet
temperature (which in some cases
would extend the draw length as
compared to the currently applicable
DOE test procedure) could increase the
repeatability of the FHR test. 87 FR
1554, 1570–1571 (Jan. 11, 2022).
However, DOE also argued that, with
both the ASHRAE 118.2–2022 and
appendix E initiation criteria, the water
heater can be considered ‘‘fully heated’’
and to have similar internal energy
content before beginning the FHR test,
although differences may be present due
to the internal water temperature
gradient throughout the tank. DOE did
not propose an amendment to include
pre-FHR test conditioning, because it
was unclear how these differences in
internal tank temperature would affect
the test results. 87 FR 1554, 1571 (Jan.
11, 2022).
In response, A.O. Smith stated that
the 15 °F initiation criterion and the
additional specificity on draw
45 ‘‘Cut-out’’ is defined in section 1 of appendix
E as ‘‘the time when or water temperature at which
a water heater control or thermostat acts to reduce
to a minimum the energy or fuel input to the
heating elements, compressor, or burner.’’
46 The draw time limit is the rated storage
capacity divided by the flow rate times 1.2 (i.e., for
a 75-gallon water heater the draw time limit would
be 30 minutes, or 75 gallons divided by 3 gpm times
1.2).
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termination in ASHRAE 118.2 would
improve consistency and repeatability
and would not conflict with the
currently applicable DOE test
procedure, and, therefore, those
provisions should be adopted. (A.O.
Smith, No. 37 at pp. 6–7) BWC also
urged DOE to consider adopting the preFHR pre-conditioning requirements
specified in ASHRAE 118.2. BWC stated
that the specifications in ASHRAE 118.2
only add parameters to achieve better
testing consistency, and that the
currently applicable test procedure may
frequently yield inconsistencies from
short pre-draws prior to the initiation of
the FHR test, thereby causing storage
water heaters to be unable to meet the
test procedure’s 125 °F ± 5 °F
requirement. BWC stated that changes to
the pre-FHR preconditioning
requirements were agreed to by
manufacturers during the development
of ASHRAE 118.2, and that
manufacturers are prepared to
undertake the burden of any re-testing
in favor of a more robust test method.
(BWC, No. 33 at pp. 4–5)
In response, DOE notes that
commenters did not indicate the impact
of this change on rated values of
products nor did they provide any data
in that regard. Additionally, DOE is not
aware of storage water heaters which are
not able to meet the 125 °F ± 5 °F outlet
temperature requirement, but if this is
demonstrated to be a problem, the
Department would address the impacted
products in a future rulemaking once
more data are collected. Although the
Department acknowledges the potential
benefits to consistency and repeatability
that may accompany a pre-FHR
preconditioning requirement, without a
clear understanding of the associated
impact on ratings, DOE is not adopting
this change to the Federal test procedure
at this time.
Additionally, DOE notes that the draw
time limit in section 7.3.3.3 of ASHRAE
118.2–2022 is a function of the
‘‘nominal’’ capacity of the water heater
(in gallons or liters). Nominal capacity
is typically not equal to the rated storage
volume, and there is no standardized
methodology in appendix E or in
ASHRAE 118.2–2022 to determine
nominal capacity; hence, there is a
concern that the draw time limits could
be different for two identical water
heaters labeled at two different nominal
capacities. If DOE were to adopt the
essence of the initiation criteria in
ASHRAE 118.2–2022, DOE would
consider substituting ‘‘nominal
capacity’’ for ‘‘rated storage volume’’
(because rated storage volume is a
standardized metric with a test method
associated with it in section 5.2.1 of
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appendix E). This deviation could cause
additional testing costs for
manufacturers.
For these reasons, DOE is maintaining
the FHR test initiation criteria currently
found in appendix E, which provide
that the preconditioning draw can be
terminated any time after cut-in, and the
water heater is operated until cut-out.
Once the maximum mean tank
temperature is observed after cut-out,
the initial draw of the FHR test begins.
24-Hour Simulated-Use Test Initiation
Criteria
Similar to the initiation criteria
discussed in the previous section for the
FHR test, section 7.4.2 of ASHRAE
118.2–2022 includes criteria for a pre24-hour simulated-use test draw, which
ends after either the outlet temperature
drops by 15 °F or the draw time limit is
reached. Section 5.4.2 of the currently
applicable appendix E requires that the
water heater sit idle for 1 hour prior to
the start of the 24-hour simulated-use
test, during which time no water is
drawn from the unit and no energy is
input to the main heating elements, heat
pump compressor, and/or burners.
Appendix E provides no instruction on
how to condition the tank prior to this
one hour. However, as discussed in the
previous section, it remains unclear
how the outlet temperature drop criteria
and the draw time limit will affect the
internal tank temperature at the start of
the 24-hour simulated-use test and how
this difference in internal tank
temperatures will affect the test results.
In the January 2022 NOPR, DOE did
not propose to amend appendix E to
include the April 2021 ASHRAE Draft
118.2 24-hour simulated-use test
initiation criteria (which was
substantially the same as the 24-hour
simulated-use test initiation criteria
included in ASHRAE 118.2–2022) and
invited comment and data that provide
information on the impact of this update
on UEF results. 87 FR 1554, 1573 (Jan.
11, 2022).
On this topic, BWC argued that the
initiation criteria in ASHRAE Standard
118.2 should also be adopted for the 24hour simulated-use test so as to improve
the repeatability and reproducibility of
the test procedure. (BWC, No. 33 at pp.
4–5) DOE considered this comment, as
well as those received regarding the
FHR test initiation criteria, and has
determined that it still lacks the
necessary data that would provide a
clear understanding of the impact that
this update would have on ratings.
Accordingly, for the same reasons stated
in the previous section, DOE is not
adopting this change in this final rule.
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FHR Test Termination Temperature
Section 7.3.3.4 of ASHRAE 118.2–
2022 includes additional criteria
regarding water draws during the FHR
test, as compared to the current DOE
test procedure. The FHR test required in
section 5.3.3 of appendix E specifies a
series of water draws over the course of
one hour. After each water draw is
initiated, the draw is terminated when
the outlet water temperature decreases
15 °F from the maximum outlet water
temperature measured during the draw.
For example, if after initiating a water
draw, the outlet water temperature
reaches a maximum temperature of
125 °F, the water draw would continue
until the outlet water temperature drops
to 110 °F, at which time the water draw
would be terminated. Similar to the
public review drafts of ASHRAE 118.2,
section 7.3.3.4 of ASHRAE 118.2–2022
specifies that water draws during the
FHR test terminate if either: (1) The
outlet water temperature decreases by
the quantity of nominal delivery
temperature minus 110 °F from the
maximum outlet water temperature 47 or
(2) the outlet water temperature
decreases to 105 °F, regardless of the
maximum outlet water temperature
measured during the draw. Setting a
minimum temperature threshold of
105 °F would reflect that, in practice,
consumers would likely stop drawing
water when it gets below 105 °F, as the
water would no longer be considered
‘‘hot.’’
A temperature of 105 °F would be the
FHR test termination temperature if the
maximum outlet temperature were
120 °F (a 15 °F difference) as per the
current DOE test procedure. 120 °F is
the lower end of the outlet temperature
tolerance band specified in section
5.2.2.2 of appendix E (i.e., 125 °F ± 5 °F).
However, as discussed in section
III.A.4.b of this document, there exist
low-temperature water heaters that are
not capable of maintaining these
temperatures when tested to the flow
rates required in section 5.2.2.2 of
appendix E, and this raises the question
of whether a criterion for ending a draw
when the outlet temperature reaches
105 °F would be representative for all
consumer water heaters and residentialduty commercial water heaters.
In this rulemaking, DOE sought
information and feedback from
stakeholders on the potential impacts
and implications of setting an FHR test
47 The nominal delivery temperature in section
2.4 of the appendix E test procedure is 125 °F, and
125 °F¥110 °F = 15 °F. Thus, for a nominal delivery
temperature of 125 °F, ASHRAE 118.2–2022 and the
DOE test procedure both use a 15 °F drop to
indicate when the draw must be terminated.
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termination temperature such as 105 °F.
In particular, DOE was interested in
data which would determine the
representativeness of a 105 °F minimum
temperature based on consumer use and
expectations. 85 FR 21104, 21109 (April
16, 2020). While several stakeholders
generally supported the use of a
termination temperature, two
manufacturers indicated that more
testing and investigation are necessary
prior to adopting this. 87 FR 1554, 1571,
1572 (Jan. 11, 2022). In commenting on
the April 2020 RFI, Rheem suggested
100 °F instead to account for lowtemperature water heaters. (Rheem, No.
14 at p. 3) In the January 2022 NOPR,
DOE tentatively determined that, based
on a review of existing test data, the
105 °F termination temperature criterion
would affect only a small number of
tests, if any. Additionally, DOE noted
that Rheem’s suggested 100 °F
termination temperature would most
likely not be representative for all types
of consumer water heaters and
residential-duty commercial water
heaters. Given the need for further
evaluation of the specific termination
temperature and its potential impacts,
DOE did not propose to adopt a
termination temperature for the FHR
test in the January 2022 NOPR. 87 FR
1554, 1572 (Jan. 11, 2022).
In response to the January 2022
NOPR, BWC reiterated that DOE should
include the 105 °F termination
temperature established in ASHRAE
Standard 118.2 to provide additional
clarity and reflect representative usage.
(BWC, No. 33 at p. 4) However,
commenters did not provide additional
data or consumer usage information to
indicate whether 105 °F is
representative of the minimum delivery
temperature consumers generally
expect. DOE was likewise unable to
obtain widespread field use data on its
own initiative.
As of this final rule, there remains
significant uncertainty regarding what
the value of the termination temperature
should be. As noted previously, Rheem
indicated 100 °F should be used to
account for low-temperature water
heaters. Section 7.3.3.4 of ASHRAE
118.2–2022 uses a 105 °F minimum
termination temperature, which was
recommended by several stakeholders.
DOE did not receive, nor has DOE
found, any additional data regarding the
minimum delivery temperature
consumers would generally expect.
However, should the water heater
provide a maximum delivery
temperature during the test which is
lower than 120 °F (which may
potentially occur even if the unit’s
controls are adjusted properly according
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to section 5.2.2 of appendix E), a 15 °F
temperature drop would result in
termination below 105 °F. DOE expects
this would impact a relatively small
number of units, but at this time, there
is inadequate test data to indicate how
frequently this may occur, which types
of products would be affected, and how
they would be affected by a specific
termination temperature.
Given these considerations, DOE is
not adopting a minimum termination
temperature for the FHR test in this
rulemaking.
FHR Test Final Draw Volume
Section 5.3.3.3 of appendix E includes
a provision for the FHR test requiring
that if the final draw is not initiated
prior to one hour from the start of the
test, then a final draw is imposed at the
elapsed time of one hour. In this
situation, calculations presented in
section 6.1 of appendix E are used to
determine the volume drawn during the
final draw for purposes of calculating
FHR. The volume of the final draw is
‘‘scaled’’ based on the temperature of
the water delivered during the final
draw as compared to the temperature of
the water delivered during the previous
draw to account for the water removed
in the final draw being at a lower
temperature than previous draws. The
scaled final draw volume is added to the
total volume drawn during the prior
draws to determine the FHR. ASHRAE
118.2–2022 does not include a final
draw volume scaling calculation for the
case in which a draw is not in progress
at one hour from the start of the test and
a final draw is imposed at the elapsed
time of one hour. Instead, the ASHRAE
118.2–2022 method calculates FHR as
the sum of the volume of hot water
delivered giving full credit to the final
draw.
The methodology for conducting the
FHR test, and in particular the issue of
whether to scale the final draw, was
considered by DOE in a final rule that
was published in the Federal Register
on May 11, 1998 (the May 1998 Final
Rule). 63 FR 25996. In the May 1998
Final Rule, DOE determined that scaling
the final draw volume based on the
outlet water temperature was
appropriate and was included to adjust
the volume of the last draw to account
for the lower heat content of the last
draw compared to the earlier draws
with fully heated water. Id. at 63 FR
25996, 26004–26005.
In the January 2022 NOPR, after
considering comments on the April
2020 RFI, DOE proposed not to update
the final draw volume provisions in the
FHR test because DOE tentatively
determined that scaling the final draw
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volume based on outlet temperature is
more representative of the actual use in
the field. 87 FR 1554, 1573 (Jan. 11,
2022). As discussed in the January 2022
NOPR, AHRI and individual
manufacturers recommended that DOE
remove the scaling calculations to
harmonize with ASHRAE 118.2–2022,
indicating that this change would have
minimal impact on ratings. Id. at 87 FR
1572. CSA, however, raised concerns
with that approach, because water is
usually tempered by the end user, and
the commenter argued that a water
heater that delivers a volume of water at
a higher temperature should not be
credited the same as one that delivers
roughly the same volume at a lower
temperature. CSA also noted that
removing the scaling of the final draw
volume could possibly move water
heaters to a higher draw pattern. Id.
After considering these comments,
DOE noted in the January 2022 NOPR
that the scaling of the final draw
accounts for the possible lower heat
content of the last draw as compared to
earlier draws. DOE further explained
that the test procedure specifies a
constant flow rate throughout testing,
and, as water is drawn from a typical
non-flow-activated water heater, the
water temperature decreases. As the
temperature of the water delivered by
the water heater decreases, mixing
valves at the point of use will reduce the
amount of cold water being mixed with
the hot water in order to maintain the
same delivery temperature to the
consumer. If the water from the water
heater is at a lower temperature, more
of this hot water will be required to
reach the correct temperature at the
fixture. Thus, DOE tentatively
determined that scaling the final draw
volume based on outlet temperature is
more representative of the actual use in
the field. 87 FR 1554, 1572–1573 (Jan.
11, 2022). Furthermore, DOE also noted
that if the scaling calculation were
removed, many water heaters would
have a different FHR than under the
currently applicable appendix E, and
some would change draw pattern bins,
which would require retesting for UEF
and thereby increase manufacturer
burden. Id.
In response, BWC strongly disagreed
with DOE’s position that scaling the
final draw based on outlet temperature
is representative of field use. BWC
reiterated its earlier comments that
scaling should not be necessary and
would potentially lead to unrepeatable
test results depending on the timing of
the last draw (e.g., creating the
possibility of two different FHR ratings
for the same product). BWC instead
recommended the procedure in
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ASHRAE Standard 118.2, where the
sum of the volume of hot water
delivered is used without scaling the
final draw. BWC argued that this
approach would more fairly account for
water heated by the product. (BWC, No.
33 at pp. 4–5)
After considering BWC’s comment,
DOE maintains that when the final draw
is imposed at the end of the FHR test,
scaling the volume of water drawn by
temperature is representative and
appropriate. Scaling the final draw
allows FHR to capture the difference in
hot water delivery capacity between
water heaters that provide roughly the
same amount of hot water in the final
draw, but where one water heater
provides water at a higher temperature
than the other. This is appropriate
because, as noted, the water temperature
is usually tempered at the fixture to
provide the end user with water at the
target outlet temperature. If the hot
water is at a lower temperature, more
water is required to provide the user
with water at the target temperature,
while less water would be needed if the
water is at a higher temperature.
Therefore, DOE has concluded that it is
appropriate for FHR to reflect this
difference in capacity, which would not
be accounted for if the scaling
calculation is removed. DOE also notes
that, at this time, there is limited
information available to assess the
potential impacts of removing the
scaling calculation on UEF and FHR
ratings, and as a result DOE is not
amending the appendix E test procedure
to include the full volume of the final
draw.
24-Hour Simulated-Use Test Standby
Period Duration
Appendix E includes a standby 48
loss measurement period between the
first and second draw clusters 49 of the
24-hour simulated use test. During this
time, temperature data is recorded and
used to calculate the standby heat loss
coefficient. See section 5.4.2 of
appendix E. Sections 7.4.3.1 and 7.4.3.2
of ASHRAE 118.2–2022 add a condition
that the standby period data can be
recorded between the first and second
draw clusters only if the time between
the observed maximum mean tank
temperatures after cut-out following the
48 ‘‘Standby’’ is defined in section 1.12 of
appendix E as ‘‘the time, in hours, during which
water is not being withdrawn from the water
heater.’’
49 A ‘‘draw cluster’’ is defined in section 1 of
appendix E as ‘‘a collection of water draws initiated
during the 24-hour simulated-use test during which
no successive draws are separated by more than 2
hours.’’ There are two draw clusters in the very
small draw pattern and three draw clusters in the
low, medium, and high draw patterns.
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first draw cluster to the start of the
second draw cluster is greater than or
equal to 6 hours. Otherwise, the standby
period data would be recorded after the
last draw of the test. This condition
would provide a sufficiently long
standby period to determine standby
loss, which might make this calculation
more repeatable and the results more
representative of standby losses
experienced in an average period of use.
However, this might also cause the test
to extend beyond a 24-hour duration.
The currently applicable DOE test
procedure does not have a 6-hour
minimum for a standby period between
the first and second draw clusters of the
24-hour simulated use test. However,
section 5.4.2 of appendix E states, ‘‘In
the event that the recovery period
continues from the end of the last draw
of the first draw cluster until the
subsequent draw, the standby period
will start after the end of the first
recovery period after the last draw of the
simulated-use test, when the
temperature reaches the maximum
average tank temperature, though no
sooner than five minutes after the end
of this recovery period. The standby
period shall last eight hours, so testing
will extend beyond the 24-hour
duration of the simulated-use test.’’ As
such, DOE does currently have a
minimum standby period duration, but
only under the particular case that there
is no opportunity to observe standby
operation between the first draw cluster
and the second draw cluster.
In the April 2020 RFI, the Department
requested comments on potentially
adding a minimum standby period
length of 6 hours and the associated
data collection and calculations. 85 FR
21104, 21110 (April 16, 2020).
Commenters were split on the
appropriateness of this amendment,
with some stakeholders noting a key
concern would be the extension of the
total test period time to over 24 hours
in many cases. 87 FR 1554, 1574 (Jan.
11, 2022).
The standby heat loss coefficient (i.e.,
UA) is the main result calculated from
the data recorded during the standby
period. DOE reviewed its available test
data and found that, generally, the
standby period duration has little effect
on the UA value, and the UA value in
turn has very little effect on UEF. As
discussed in the January 2022 NOPR,
UA is used only to adjust the daily
water heating energy consumption to
the nominal ambient temperature of
67.5 °F (19.7 °C); given that the ambient
temperature range is relatively narrow
(i.e., 65 °F to 70 °F (18.3 °C to 21.1 °C)),
the adjustment has only a minimal
impact on the daily water heating
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energy consumption. 87 FR 1554, 1574
(Jan. 11, 2022).
In commenting on the January 2022
NOPR, BWC generally disagreed with
DOE’s tentative determination that
including a 6-hour standby period
minimum would not significantly
impact UEF ratings. BWC also
mentioned that it has experienced
difficulty having adequate time to
calculate the standby loss coefficient
after the first draw cluster. Thus, BWC
reiterated its support for the
methodology in ASHRAE 118.2–2022
but stated that the company would like
time to examine this matter before
commenting further. (BWC, No. 33 at p.
6) BWC did not provide further
comments or data on this topic in
response to the July 2022 SNOPR.
Considering that DOE did not receive
further comments demonstrating a
quantifiable impact of the standby
period length on the UEF, DOE
concludes, as initially presented in the
January 2022 NOPR, that based on its
test data, the duration of the standby
period does not significantly impact the
UEF result. Therefore, in order to
minimize burden (i.e., total test
duration) on manufacturers and
laboratories while still allowing results
to be representative, repeatable, and
reproducible, DOE is not amending the
appendix E test procedure to require the
standby period to be a minimum of 6
hours in duration.
C. Test Conditions and Tolerances
In the January 2022 NOPR, DOE made
a number of proposals to the test
conditions and tolerances that were
intended to improve representativeness,
reduce testing burden, and/or
harmonize with industry test methods.
87 1554, 1558–1559 (Jan. 11, 2022).
These proposals included changes to the
electric supply voltage tolerance,
ambient condition tolerances, gas
supply pressure and manifold pressure
tolerances, and flow rate tolerances for
certain water heaters. Id. In addition, in
the July 2022 SNOPR, DOE made
supplemental proposals regarding the
tolerance on flow rate during the UEF
test for models with rated storage
volumes less than 2 gallons and max
GPM less than 1 gallon, and regarding
optional test conditions for heat pump
water heaters. 87 FR 42270, 42273 (July
14, 2022). These proposals were
intended to improve repeatability and
reproducibility and harmonize with
industry testing practices, respectively.
Id.
In response to the January 2022 NOPR
proposals, APGA provided general
comments stressing the importance of
ensuring accuracy, repeatability, and
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reproducibility in a test procedure that
is not unduly burdensome to conduct.
(APGA, No. 38 at pp. 1–2) AHRI
indicated its support of DOE’s proposals
to reduce test burden; specifically, AHRI
supported increasing test tolerances for
ambient temperature and relative
humidity, and extending untested
provisions to include electric
instantaneous water heaters. (AHRI, Jan.
27, 2022 Public Meeting Transcript, No.
27 at p. 40)
As previously discussed in section I.A
of this final rule, DOE’s efforts are
aligned with EPCA requirements to
create test procedures that are
representative of average use without
being unduly burdensome to conduct.
(42 U.S.C. 6293(b)(3)) Each of the
proposed changes to test conditions and
tolerances, along with specific
stakeholder comments received and
DOE’s responses, are discussed further
in the subsections that immediately
follow.
1. Supply Water Temperature
Measurements
Section 2.3 of the currently applicable
appendix E specifies maintaining the
supply water temperature at 58 °F ± 2 °F
(14.4 °C ± 1.1 °C). During the 24-hour
simulated-use test, maintaining the
supply water temperature within this
range can be difficult at the immediate
start of a draw due to the short time
between draw initiation and the first
measurement at 5 seconds (with
subsequent measurements every 3
seconds thereafter), as required by
sections 5.4.2 and 5.4.3 of appendix E.
In some test configurations, particularly
during the lower flow rate water draws,
the inlet water and piping may retain
heat from a previous draw, causing the
water entering the unit during the initial
measurements to be slightly outside of
tolerance. Any supply water
temperature reading outside of the test
tolerances would invalidate a test.
However, due to the small percentage of
total water use that would be affected,
supply water temperatures that are
slightly out of tolerance for the first one
or two data points would have a
negligible effect on the overall test
result.50 This issue is less evident
during the FHR test, which specifies an
initial temperature measurement 15
seconds after the start of the water draw.
This is not an issue during the Max
50 For example, the first two temperature readings
would reflect 8 seconds of water flow, in
comparison to total water draw durations ranging
from 1 minute to over 8 minutes, according to the
water draw patterns defined in Tables III.1, III.2,
III.3, and III.4 of appendix E.
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GPM test due to the system being in
steady state during the entire test.
In the April 2020 RFI, DOE requested
feedback on whether one or two supply
water temperature data points outside of
the test tolerance at the beginning of a
draw would have a measurable effect on
the results of the test. 85 FR 21104,
21111 (April 16, 2020). DOE further
requested feedback on whether it should
consider relaxing the requirement for
supply water temperature tolerances at
the start of a draw, and if so, which
methods are most appropriate for doing
so while maintaining accuracy and
repeatability. Id. at 85 FR 21111–21112.
DOE received comments regarding these
tolerances from stakeholders including
AHRI, A.O. Smith, NEEA, Rheem, BWC,
CSA, Rinnai, and SMTI. These
comments are summarized and
discussed in section III.C.3.a of the
January 2022 NOPR. 87 FR 1554, 1576–
1577 (Jan. 11, 2022).
In response to comments made on the
April 2020 RFI, DOE proposed in the
January 2022 NOPR to increase the time
between initiating the draw and first
measurement of supply water
temperature from 5 seconds to 15
seconds in sections 5.4.2 and 5.4.3 of
appendix E, as recommended by the
commenters. 87 FR 1554, 1577 (Jan. 11,
2022). DOE reasoned that the proposed
change may, if adopted, reduce test
burden by reducing the occurrence of a
test being invalidated (which would
require re-testing) due to the first one or
two water temperature readings
exceeding the defined temperature
tolerance. Further, this proposed change
would eliminate the need to amend the
supply water temperature tolerances
which, outside of the time period at the
start of a draw, are relatively easy to
maintain. Id.
In response to the January 2022
NOPR, A.O. Smith reiterated its
previous comment that there would be
no measurable effect on test results by
allowing one or two supply water
temperature data points outside of the
current test tolerance at the beginning of
a draw. The commenter suggested that
DOE should adopt the test set-up
described in ASHRAE 118.2–2022,
which includes a purge line designed by
third-party laboratories to help achieve
tolerances on supply water temperature.
A.O. Smith also commented that
widening tolerances in certain cases
may ultimately cause variations in test
results. (A.O. Smith, No. 37 at p. 5) In
contrast, BWC supported DOE’s
proposal to increase the span between
the first draw initiation and the first
temperature measurement from 5
seconds to 15 seconds because it would
reduce testing burden; the 5-second
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time interval requires significant and
frequent purging which, if not
conducted, may invalidate tests. (BWC,
No. 33 at p. 7) In response to A.O.
Smith, DOE reiterates its position, as
previously stated in the January 2022
NOPR, that although one or two
measurements outside the current
tolerance may not have an effect on test
results, DOE has chosen to alleviate the
issue of potential test invalidation by
instead increasing the time between
initiating the draw and first
measurement of supply water
temperature. Id.
After considering these comments,
DOE has decided to adopt the proposal
from the January 2022 NOPR to increase
the time between initiating the draw
and first measurement from 5 seconds to
15 seconds in sections 5.4.2 and 5.4.3 of
appendix E. In response to A.O. Smith’s
suggestion that DOE adopt the test setup in ASHRAE 118.2–2022, as
discussed in detail in section III.B.2.c of
this document, DOE is maintaining the
current set-up directions for inlet water
temperature measurement in appendix
E and not incorporating the updates
found in the ASHRAE 118.2–2022
figures because the addition of a bypass
line and thermal break was determined
to be optional. However, increasing the
time of first recordation of the supply
water temperature measurement after
the start of a draw from being taken at
5 seconds to being taken at 15 seconds
will allow units to reach a supply
temperature within tolerance without
need for modifications to the test set-up.
2. Gas Pressure
For gas-fired water heaters, sections
2.7.2 and 2.7.3 of the currently
applicable appendix E require
maintaining the gas supply pressure in
accordance with the manufacturer’s
specifications; or if the supply pressure
is not specified, maintaining a supply
pressure of 7 to 10 inches of water
column (1.7 to 2.5 kPa) for natural gas
and 11 to 13 inches of water column
(2.7 to 3.2 kPa) for propane gas. In
addition, for gas-fired water heaters
with a pressure regulator, sections 2.7.2
and 2.7.3 of the currently applicable
appendix E require the regulator outlet
pressure to be within ±10 percent of the
manufacturer’s specified manifold
pressure.
In the January 2022 NOPR, DOE noted
that from a review of product literature,
DOE found that many gas-fired water
heaters with modulating input rate
burners have a factory preset manifold
pressure that is computer-controlled
and cannot be adjusted directly.
Further, the manufacturer-specified
manifold pressure typically refers to
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when the water heater is operating at
the maximum firing rate. As a result,
and after considering comments on the
April 2020 RFI, DOE proposed to
remove the ±10 percent manifold
pressure tolerance for certain gas-fired
water heaters, recognizing that some of
these products do not provide the
capability to adjust the manifold
pressure. 87 FR 1554, 1578–1579 (Jan.
11, 2022). DOE also proposed the
addition of an absolute manifold
pressure tolerance of ±0.2 inches water
column, which would be used for gasfired water heaters with a zero-governor
valve for which the ±10 percent
tolerance would be overly restrictive. Id.
For example, applying the ±10 percent
to a manufacturer recommended gas
pressure of 0.1 inches water column
would result in a tolerance of ±0.01
inches of water column, which is less
than both the accuracy and precision
tolerances required for gas pressure
instrumentation within section 3.1 of
the currently applicable appendix E.
Further, DOE proposed that the required
gas pressures within appendix E apply
when operating at the manufacturer’s
specified input rate or, for modulating
input rate water heaters, the maximum
input rate. Id.
DOE did not receive comments in
response to the previously discussed
amendments to sections 2.7.2 and 2.7.3
of appendix E proposed in the January
2022 NOPR concerning manifold
pressure tolerance for gas-fired water
heaters. Accordingly, DOE is adopting
these amendments in this final rule for
the reasons previously stated.
3. Input Rate
In addition to the gas pressure
requirements, section 5.2.3 of the
currently applicable appendix E test
procedure requires maintaining an
hourly Btu rating (i.e., input rate) that is
within ±2 percent of the value specified
by the manufacturer (i.e., the nameplate
value). DOE has observed during testing
that an input rate cannot be achieved
that is within ±2 percent of the
nameplate value while maintaining the
gas supply pressure and manifold
pressure within the required ranges for
some gas-fired water heaters. In such
instances, it is common practice for the
testing laboratory to modify the size of
the orifice that is shipped with the
water heater; for example, the testing
laboratory may enlarge the orifice to
allow enough gas flow to achieve the
nameplate input rating within the
specified tolerance, if the input rate is
too low with the orifice as supplied. For
commercial water heating equipment,
DOE addressed this issue by specifying
in the product-specific enforcement
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provisions that, if the fuel input rate is
still not within ±2 percent of the rated
input after adjusting the manifold and
supply pressures to their specified
limits, DOE will attempt to modify the
gas inlet orifice. 10 CFR 429.134(n)(ii).
In the April 2020 RFI, DOE requested
comment on whether provisions should
be added to the test procedure at
appendix E to address water heaters that
cannot operate within ±2 percent of the
nameplate rated input as shipped from
the factory and how this issue should be
addressed. 85 FR 21104, 21112 (April
16, 2020). On this topic, DOE received
comments from manufacturers and their
representatives, including AHRI,
Rheem, Rinnai, BWC, and CEC,
suggesting various methods to achieve
the ±2 percent tolerance. These
comments are summarized and
discussed in the January 2022 NOPR. 87
FR 1554, 1579 (Jan. 11, 2022).
After considering these comments,
DOE proposed in the January 2022
NOPR to add provisions to appendix E
to provide further direction for
achieving an input rate that is ±2
percent of the nameplate value specified
by the manufacturer. 87 FR 1554, 1579
(Jan. 11, 2022). Specifically, DOE
proposed to modify section 5.2.3 of
appendix E to require that the following
steps be taken to achieve an input rate
that is ±2 percent of the nameplate value
specified by the manufacturer:
(1) Attempt to increase or decrease the
gas outlet pressure within ±10 percent
of the value specified on the nameplate
to achieve the nameplate input (within
±2 percent).
(2) If the fuel input rate is still not
within ±2 percent of the nameplate
input, increase or decrease the gas
supply pressure within the range
specified on the nameplate.
(3) If the measured fuel input rate is
still not within ±2 percent of the
certified rated input, modify the gas
inlet orifice as required to achieve a fuel
input rate that is ±2 percent of the
nameplate input rate.
Id.
Regarding commenters’ suggestion to
check for leaks as an additional step in
the process, DOE noted that gas leak
detection should be part of a test
laboratory’s normal operating
procedures, and, therefore, detection
does not require specification within
DOE’s test procedures. 87 FR 1554, 1579
(Jan. 11, 2022). DOE also explained that
the purpose of adjusting the orifice
during testing is to ensure that the
performance of the water heater is
representative of performance at the Btu
rating specified by the manufacturer on
the product’s nameplate, which informs
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the field installation conditions.
Allowing for adjustment of the orifice
reduces test burden and improves
repeatability by providing test
laboratories with a last resort to
maintain the hourly Btu rating as
specified by the manufacturer. Further,
DOE noted that the proposal that the
orifice be modified would occur only
after other options have been exhausted.
Lastly, DOE proposed that should a unit
fail to achieve an input within the 2
percent tolerance, DOE would continue
testing with the measured input value as
opposed to the rated value (i.e., the fuel
input rate found via testing would be
used for the purpose of determining
compliance). 87 FR 1554, 1579–1580
(Jan. 11, 2022).
In response to DOE’s proposals on
this topic in the January 2022 NOPR,
AHRI agreed with the Department’s
proposal to first adjust the manifold
pressure and then modify the orifice if
an input rate within 2 percent of the
nameplate input rating is not achieved.
(AHRI, No. 40 at pp. 1–2)
Rheem, AHRI, and BWC commented
that if the unit cannot reach input rates
within ±2 percent of the nameplate rate,
the unit is likely faulty, and the test
results should not be accepted. (Rheem,
No. 31 at pp. 2–3; AHRI, No. 40 at pp.
1–2; BWC, No. 33 at p. 8) AHRI
suggested that if this occurs, the
manufacturer should be contacted.
AHRI also stated that laboratory testing
should only be performed by qualified
laboratory personnel, adding that the
architecture of oil-fired water heaters
also introduces additional complexity
for these products. (AHRI, No. 40 at p.
2) BWC also commented that last-resort
orifice adjustments should only be
performed by qualified laboratory
personnel, and indicated that DOE may
wish to reference language in Section
A1.3.2.1.10 of the AHRI Residential
Water Heater Operations Manual.51
(BWC, No. 33 at p. 7)
In response to these comments, DOE
agrees with commenters that testing
should generally be performed at
51 AHRI maintains an Operations Manual for
Residential Water Heater Certification Program
(AHRI Residential Water Heaters Operations
Manual), which addresses how testing will be done
in the AHRI certification program. Section
A1.3.2.1.10 of the January 2022 edition of the AHRI
Operations Manual for its Residential Water Heaters
states: ‘‘If adjusting the manifold pressure does not
achieve the rated input, the operator shall re-orifice
the unit using an alternate orifice supplied by the
manufacturer. [Note: Manufacturers are to supply
test facility with a selection of orifices for use at the
test facility. When a test unit is re-orificed, the test
facility will notify the manufacturer of the alternate
orifice used, and the manufacturer shall re-supply
the test facility with a replacement orifice.’’ See:
www.ahrinet.org/Portals/OM/RWH_OM.pdf. (Last
accessed July 21, 2022.)
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accredited laboratory institutions by
qualified personnel. In response to
BWC’s suggestion that DOE reference
section A1.3.2.1.10 of the AHRI
Residential Water Heater Operations
Manual, DOE notes that the
amendments to section 5.2.3 of
appendix E are consistent with the
instructions in the AHRI Residential
Water Heater Operations Manual in that
they both require a modification to the
orifice, with the AHRI Operations
Manual requiring the testing laboratory
to ‘‘re-orifice’’ the unit and the language
DOE is adopting requiring the test
agency to ‘‘modify’’ the orifice. The
finalized amendment would provide a
more flexible approach than the
language of section A1.3.2.1.10 of the
AHRI Residential Water Heater
Operations Manual by not requiring
involvement by the water heater
manufacturer in any modifications to
the orifice. DOE notes that a unit not
achieving the nameplate input rate
within ±2 percent could represent a
malfunctioning unit or a broader issue
in the design of the model. Under the
proposed test approach, such models
would be tested and evaluated for
compliance based on its actual
performance.
With regards to oil-fired water
heaters, the amended section 5.2.3
provisions to appendix E reference the
fuel oil supply requirements in section
2.7.4 of appendix E, which provide
adequate direction for the adjustment.
After evaluating these comments,
DOE is adopting modifications to
appendix E and 10 CFR 429.134
concerning input rate provisions as
proposed in the January 2022 NOPR and
for the reasons previously stated.
4. Ambient Test Condition Tolerances
Section 2.2 of appendix E specifies
maintaining the ambient air temperature
between 65.0 °F and 70.0 °F (18.3 °C and
21.1 °C) on a continuous basis for all
types of consumer water heaters (and
residential-duty commercial water
heaters) other than heat pump water
heaters. For heat pump water heaters,
the dry-bulb (ambient air) temperature
must be maintained between 67.5 °F
±1 °F (19.7 °C ±0.6 °C), and the relative
humidity must be maintained at 50
percent ±2 percent throughout the test.
Appendix E does not specify a relative
humidity tolerance for non-heat pump
water heaters. Similar to the supply
water temperature discussed previously,
a brief measurement of air temperature
or relative humidity that is only
minimally outside of the test tolerance
would invalidate a test, but likely would
have a negligible effect on the results of
the test, as the total time out of tolerance
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40435
would be insignificant compared to the
total time of the test. In the April 2020
RFI, DOE requested feedback on
whether the tolerances for ambient air
temperature and relative humidity are
difficult to maintain at the start of a
draw, and if so, whether DOE should
consider relaxing these requirements at
the start of a draw and to what extent.
85 FR 21104, 21112 (April 16, 2020).
After considering comments received
on the April 2020 RFI, DOE proposed in
the January 2022 NOPR to change the
ambient temperature requirement for
non-heat pump water heaters to an
average of 67.5 °F ± 2.5 °F, with a
maximum deviation of 67.5 °F ± 5 °F, as
opposed to only a maximum deviation
of 67.5 °F ± 2.5 °F as currently specified
in the test procedure. 87 FR 1554, 1578
(Jan. 11, 2022). DOE reasoned that such
a change could, if adopted, reduce the
need to re-run tests in instances in
which the results of the invalid test and
the valid test would not differ
significantly, and, therefore, reduce test
burden. Id. DOE also noted that through
a review of its available test data, DOE
found that short fluctuations in ambient
temperature have little to no effect on
the test results of non-heat pump water
heaters. Id.
For heat pump water heaters, DOE
proposed in the January 2022 NOPR to
change the dry-bulb temperature
requirement for heat pump water
heaters to an average of 67.5 °F ± 1 °F
during recoveries and an average of
67.5 °F ± 2.5 °F when not recovering,
with a maximum deviation of 67.5 °F ±
5 °F, as opposed to only a maximum
deviation of 67.5 °F ± 1 °F as currently
specified in the test procedure. Id. DOE
reasoned that this proposed change
would maintain the stringency of the
dry-bulb temperature requirement while
allowing for short deviations from the
targeted dry-bulb temperature range,
which would reduce the need to re-run
tests in instances in which the results of
the invalid test and the valid test would
not differ significantly, and, therefore,
reduce test burden. Id.
For heat pump water heaters, DOE
also proposed in the January 2022
NOPR to increase the absolute relative
humidity tolerance from ±2 percent to
±5 percent across the entire test, with
the average relative humidity between
50 percent ±2 percent during recoveries.
87 FR 1554, 1578 (Jan. 11, 2022). DOE
reasoned that this change, if adopted,
would reduce test burden by reducing
the need to re-run tests in instances in
which the results of the invalid test and
the valid test would not differ
significantly. Id.
As noted, the currently applicable
appendix E does not specify a relative
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humidity tolerance for non-heat pump
water heaters. In the January 2022
NOPR, DOE explained that (as initially
described in the April 2020 RFI), DOE
conducted exploratory testing to
investigate the effect of relative
humidity on the measured UEF values
of two consumer gas-fired instantaneous
water heaters that are flow-activated and
have less than 2 gallons of storage
volume, one using non-condensing
technology and the other using
condensing technology. 87 FR 1554,
1578 (Jan. 11, 2022). For each model,
testing was performed at a relative
humidity of 50 percent and at a relative
humidity of 80 percent, and DOE found
that increasing relative humidity from
50 percent to 80 percent resulted in a
maximum change in UEF for the noncondensing and condensing models of
0.011 and 0.015, respectively. DOE
noted that UEF is reported to the nearest
0.01 (see 10 CFR 429.17(b)(2)), and,
thus, a change in UEF on the order of
0.01 to 0.02 as suggested by DOE’s test
results could be considered as
substantively impacting the test results.
However, DOE did not propose to adopt
a tolerance on relative humidity in the
January 2022 NOPR, noting that it was
still examining this issue. DOE
requested further comment and test data
on whether a relative humidity
requirement should be added to
appendix E for non-heat pump water
heaters. Id.
In response to the proposals made in
the January 2022 NOPR concerning
ambient air temperature and relative
humidity tolerances, AHRI indicated its
support of DOE’s proposals to reduce
test burden; specifically, AHRI
supported increasing test tolerances for
ambient temperature and relative
humidity. (AHRI, Jan. 27, 2022 Public
Meeting Transcript, No. 27 at p. 40)
NEEA and CA IOUs suggested that DOE
should specify a relative humidity level
of 50 percent ± 5 percent for all water
heater types as was proposed for heat
pump water heaters in the January 2022
NOPR, which the commenters argued
would reduce test burden and ensure
that results are comparable, repeatable,
and representative across all products
and technologies. (NEEA, No. 30 at pp.
1–2; CA IOUs, No. 36 at pp. 3–4)
BWC, however, anticipated difficulty
maintaining even the proposed ±5
percent tolerance during compressor
cycling for electric heat pump water
heaters. BWC also argued that
establishing a relative humidity
tolerance when testing water heaters
other than heat pump water heaters is
unnecessary after observing low impact
on UEF rating during its testing of a gas
instantaneous water heater at both 20
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percent relative humidity and 100
percent relative humidity. (BWC, No. 33
at p. 7) In response to BWC’s comments,
DOE notes that BWC has not provided,
nor is DOE aware of, any data suggesting
that a ±5 percent relative humidity
tolerance would be difficult to maintain
for heat pump water heaters.
After considering comments on the
January 2022 NOPR, DOE is adopting
the changes to ambient air temperature
and relative humidity tolerances as
proposed. Regarding the
recommendation that DOE specify a
relative humidity level of 50 percent ±
5 percent for all water heater types, DOE
finds that it does not have adequate test
data to make such a change at this time,
but DOE will continue to further
investigate this issue.
5. Electrical Supply Voltage Tolerances
For all water heaters, section 2.7.1 of
the currently applicable appendix E
specifies maintaining the electrical
supply voltage within ±1 percent of the
center of the voltage range specified by
the manufacturer. In the April 2020 RFI,
DOE requested feedback on whether the
tolerances for electrical supply voltage
are difficult to maintain at the start of
a draw, and if so, whether DOE should
consider relaxing these requirements at
the start of a draw and to what extent.
85 FR 21104, 21112 (April 16, 2020).
In the January 2022 NOPR, after
considering comments received in
response to the April 2020 RFI, DOE
proposed to increase the electrical
supply voltage tolerance from ±1
percent on a continuous basis to ±2
percent on a continuous basis. 87 FR
1554, 1577 (Jan. 11, 2022). DOE also
proposed to add clarification that this
tolerance is only applicable beginning 5
seconds after the start of a recovery to
5 seconds before the end of a recovery
(i.e., only when the water heater is
undergoing a recovery). Id. DOE
reasoned that these proposed changes
could reduce test burden by reducing
the need to re-run tests while
maintaining the representativeness of
the test procedure. Id.
In response to these proposed
changes, DOE received comment from
BWC supporting the proposal to
increase the tolerance for electric supply
voltage. (BWC, No. 33 at p. 7)
DOE has thus determined that the
proposed changes to sections 2.7.1 and
3.7 of appendix E concerning electric
supply voltage tolerance are appropriate
and is adopting them in this final rule
for the reasons previously stated.
6. Flow Rate Tolerances
Section 5.4.2 of appendix E, Test
Sequence for Water Heaters with Rated
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Storage Volumes Greater Than or Equal
to 2 Gallons, provides that all draws
during the 24-hour simulated-use test
must be made at the flow rates specified
in the applicable draw pattern table in
section 5.5 of this appendix, within a
tolerance of ±0.25 gallons per minute
(±0.9 liters per minute). Section 5.4.3 of
appendix E, Test Sequence for Water
Heaters with Rated Storage Volume Less
Than 2 Gallons, currently does not
provide explicit instruction for the
tolerance on the flow rate.
Within the proposed amendments to
the regulatory text provided in the
January 2022 NOPR, DOE included a
proposed amendment to section 5.4.3 of
appendix E to specify that flow rates for
water heaters with rated storage volume
less than 2 gallons must be maintained
within a tolerance of ±0.25 gallons per
minute (±0.9 liters per minute). 87 FR
1554, 1603 (Jan. 11, 2022). Because this
proposed change was not addressed
explicitly in the preamble to the January
2022 NOPR, DOE raised this issue again
in the July 2022 SNOPR. 87 FR 42270,
42274 (July 14, 2022).
However, as discussed in the July
2022 SNOPR, there are models with
Max GPM delivery capacities at or
below 1.0 gallon per minute, and for
these products, the flow rate used
during draws must be the Max GPM
flow rate. A flow rate tolerance of ±0.25
gallons per minute would be too wide
for products with Max GPM flow rates
as low as 0.20 gallons per minute.
Because the flow rate tolerance
represents 25 percent of the flow rate at
1.0 gallon per minute, DOE proposed
another amendment to section 5.4.3 of
appendix E in the July 2022 SNOR to
specify that for water heaters with a
rated Max GPM of less than 1 gallon per
minute, the flow rate tolerance shall be
±25 percent of the rated Max GPM. DOE
reasoned that for such products, a flow
rate tolerance ±25 percent of the rated
Max GPM would represent the same
level of variation (on a percentage basis)
as for products rated at 1.0 gallon per
minute and subject to a tolerance of
±0.25 gallon per minute. DOE noted that
third-party laboratories are currently
technically capable of implementing
this methodology based on DOE’s own
test data. 87 FR 42270, 42274 (July 14,
2022).
In response to the July 2022 SNOPR,
ASAP, ACEEE, and NRDC expressed
support for DOE’s proposal to specify
the flow rate tolerance requirements for
water heaters with a rated storage
volume under 2 gallons. (ASAP, ACEEE,
and NRDC, No. 54 at p. 1) BWC
expressed they had not had adequate
time to conduct testing in order to
determine the impact of DOE’s proposed
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establishment of a ±25 percent of
maximum GPM threshold, and as a
result, the company had no further
comments on that proposal. (BWC, No.
48 at p. 2)
AHRI, A.O. Smith, and Rheem offered
a few potential revisions to the
proposal. AHRI requested that DOE set
a minimum tolerance of ±0.1 gpm for
the 24-hour simulated-use test for
models with maximum flow rates less
than 1 gpm because the proposed ±25
percent tolerance may be difficult to
meet for some models. (AHRI, No. 55 at
p. 2) A.O. Smith stated that the
proposed flow rate tolerances for the 24hour simulated-use test for water
heaters with a rated storage volume less
than 2 gallons would require
manufacturers to invest in more precise
equipment and may also easily
invalidate results for units with low
Max GPM values. Accordingly, A.O.
Smith requested that DOE adopt the
proposed flow rate tolerance from the
NOPR, rather than the SNOPR. (A.O.
Smith, No. 51 at pp. 2–3) Rheem
indicated that the proposed flow rate
tolerance of 25 percent of Max GPM
may be too low for water heaters with
very low max GPM and recommended
that DOE change the tolerance to the
maximum between that value and ±0.1
gpm. Rheem also recommended that all
flow rate tolerances be calculated based
on the average of the flow rate over the
entire draw, so as to help reduce the
number of invalid tests. (Rheem, No. 47
at p. 2)
As discussed previously, the lowest
Max GPM certified to DOE is currently
0.2 gpm, and DOE’s amended test
procedure must provide a reproducible
and repeatable method for testing
products with such low flow rates. DOE
has determined that a tolerance of ±0.1
gpm could offer too much variability in
test results for products rated with such
low flow rates. Specifically, a tolerance
this wide would represent ±50 percent
of the flow rate of this kind of water
heater, and because the temperature rise
through the water heater is inversely
related to the flow rate when the water
heater is constantly firing at its
maximum input rate, this variation in
flow rate can cause the temperature rise
to potentially double. As stated, DOE is
aware that third-party laboratories are
equipped with instrumentation to
measure flow rates within the tolerance
level proposed in the July 2022 SNOPR.
DOE did not receive any test data in
response to the July 2022 SNOPR
indicating that manufacturers or third
party test laboratories would not be able
to meet the tolerances proposed in the
July 2022 SNOPR. Furthermore, DOE
has concluded that a 0.1 gpm tolerance
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is too large for the lowest flow rate
models currently on the market (0.2
gpm) and would be even more
problematic if models with flow rates
below 0.2 gpm are introduced in the
future. As such, in this final rule, DOE
is adopting the flow rate tolerance
amendments to sections 5.4.2 and 5.4.3
of appendix E, as proposed in the July
2022 SNOPR.
7. Optional Test Conditions for Heat
Pump Water Heaters
In the course of this rulemaking, DOE
has received numerous comments from
stakeholders requesting that DOE
consider allowing manufacturers to
optionally rate heat pump water heaters
to test conditions other than those
currently specified in appendix E,
which are intended to be representative
of national average water and air
temperatures. Commenters noted that
heat pump operation is dependent upon
the surrounding ambient air
temperatures,52 and that there would be
significant value to providing
consumers, installers, and utilities with
efficiency representations that are closer
to the conditions for particular climates.
See 87 FR 1554, 1580 (Jan. 11, 2022) and
87 FR 42270, 42275–42276 (July 14,
2022).
For example, Lutz commented that a
single inlet water temperature may not
be representative for all cases because
this may vary by geographical location,
and, furthermore, that taking this into
account is even more important for
split-system heat pump water heaters
with an outdoor unit. (Lutz, No. 35 at p.
1) NEEA argued that, because heat
pump water heater performance can be
affected by variations in ambient
conditions, DOE should clarify what
manufacturers can report about a unit’s
performance at conditions other than
those required by the test procedure.
NEEA added that information regarding
delivery capacity and sizing guidance
would be important for installers.
(NEEA, No. 30 at p. 3)
In the January 2022 NOPR, DOE did
not propose to allow for optional
(voluntary) representations of heat
pump water heater efficiencies at nonstandard temperatures because there
52 Because heat pumps ‘‘transfer thermal energy
from one temperature level to a higher temperature
level’’ (see 42 U.S.C. 6291(27)(C) and 10 CFR 430.2),
the energy efficiency is dependent upon the
difference between temperatures that must be
overcome by the heat pump cycle. As discussed in
section III.A.2 of this document, heat pump water
heaters are typically air-source, i.e., these products
source heat from surrounding air and transfer it to
domestic hot water. Therefore, lower ambient air
temperatures, such as those experienced in colder
climates or due to seasonal differences, would
result in lower efficiencies.
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was not enough information at the time
to identify the most representative
alternate test conditions (e.g., regional
conditions). 87 FR 1554, 1580 (Jan. 11,
2022). However, commenters on the July
2022 SNOPR identified the NEEA
Advanced Water Heating Specification
(currently at version 8.0, AWHS v8.0)
provides multiple conditions which
manufacturers are providing ratings at.
87 FR 42270, 42775–42276 (July 14,
2022). Consequentially, DOE revisited
the NEEA Advanced Water Heating
Specification to determine how the test
conditions specified in that document
might be applied for optional
representations in the DOE test
procedure.
Section 2.2 of appendix E currently
specifies that the ambient air
temperature shall be maintained
between 65.0 °F and 70.0 °F (18.3 °C and
21.1 °C) on a continuous basis during
the test. Additionally, for heat pump
water heaters, that test procedure
provision provides that the dry-bulb
temperature shall be maintained at
67.5 °F ± 1 °F (19.7 °C ± 0.6 °C) and that
the relative humidity shall be
maintained at 50 percent ± 2 percent
throughout the test. EPCA requires that
the DOE test procedure must be
reasonably designed to produce test
results which measure energy efficiency
during a representative average use
cycle or period of use. (42 U.S.C.
6293(b)(3)) While the test conditions in
the current appendix E test procedure
must remain representative for the
nation as a whole, in the July 2022
SNOPR, DOE tentatively determined
that comments from interested parties
have demonstrated that allowing
additional representations of efficiency
at alternative ambient conditions could
provide consumers with additional
information about the expected
performance of heat pump water heaters
at conditions that are representative of
their specific installation circumstances.
For other types of covered products and
equipment, DOE has adopted optional
metrics for voluntary representations
where it was determined that the
primary efficiency metric would not be
representative for certain installation
conditions common for the product or
equipment.53 As discussed in the July
53 For example, on July 27, 2022, DOE published
a final rule in the Federal Register pertaining to test
procedures for direct-expansion dedicated outdoor
air systems, including provisions for optional
representations of energy efficiency when the
equipment is installed in applications where inlet
water conditions are expected to deviate
substantially from standard conditions. See 10 CFR
part 431, subpart F, appendix B, section 2.2.3(d) as
established by that final rule. 87 FR 45164, 45201
(July 27, 2022).
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2022 SNOPR, depending on the
installation location (e.g., whether the
water heater is installed in an
unconditioned space such as a garage or
attic), the ambient conditions may vary
significantly from the conditions in the
DOE test method, thereby resulting in
significantly different performance for
heat pump water heater products. Thus,
DOE reversed its position and
tentatively determined to allow for
certain optional representations for
additional ambient conditions. 87 FR
42270, 42275–42276 (July 14, 2022).
AWHS v8.0 was published by NEEA
on March 1, 2022. Though early editions
of the AWHS focused primarily on
providing more representative
performance metrics for heat pump
water heaters in cold climates, the latest
editions are now more broadly focused
on providing representative
performance metrics for heat pump
water heaters across all climates.
Performance metrics in the AWHS are
generally calculated by measuring
energy efficiency at multiple (two or
more) ambient test conditions, linearly
interpolating between the test results,
and finally calculating an ambient
temperature-weighted efficiency metric
using temperature bin data. The metric
is a cold climate efficiency (CCE) rating
for integrated heat pump water heaters
installed in semi-conditioned spaces
(i.e., garage, basement) and a seasonal
coefficient of performance (SCOP) for
split-system heat pump water heaters
(where the heat pump is separated from
the storage tank and located outdoors).
DOE tentatively determined in the July
2022 SNOPR that adopting the test
conditions in AWHS v8.0 would not
significantly increase test burden for
manufacturers who choose to provide
these ratings, because manufacturers are
already providing representations of
CCE and SCOP to NEEA’s Qualified
Products List.54 The test conditions in
AWHS v8.0 differ from the standard
conditions in appendix E in terms of
inlet water temperature, ambient drybulb temperatures, and ambient relative
humidity. A detailed discussion of these
conditions was provided in the July
2022 SNOPR. 87 FR 42270, 42276 (July
14, 2022).
In the July 2022 SNOPR, DOE
proposed to allow voluntary
representations of a new metric, EX,
analogous to UEF, at optional test
conditions for heat pump water heaters.
The subscript ‘‘X’’ would be used to
denote the set of conditions being used,
and these voluntary representations of
54 Available
at: neea.org/img/documents/
residential-unitary-HPWH-qualified-productslist.pdf (Last accessed on May 11, 2022).
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EX would not be integrated together to
form a seasonal efficiency metric—in
contrast to the methodology in AWHS
v8.0. DOE’s proposal intended to
eliminate any reduction in
representativeness caused by
assumptions in climate weighting
factors. Without substantial additional
data, DOE tentatively determined that it
would not be able to evaluate whether
or not the weighting factors in AWHS
v8.0 (used to create a weighted average
of the results at various test conditions
together into one metric, CCE or SCOP)
are representative of climates in the
United States, and, thus, DOE proposed
to allow for the use of standalone EX
representations only in a way that it is
clear to a consumer what test conditions
were used in determining the rating. 87
FR 42270, 42276–42277 (July 14, 2022).
In response to the July 2022 SNOPR,
ASAP, ACEEE, and NRDC expressed
support for DOE’s proposal to adopt
optional test conditions needed for
calculating climate-specific efficiencies.
(ASAP, ACEEE, and NRDC, No. 54 at p.
2) A.O. Smith acknowledged that
optional efficiency ratings may have
consumer utility and stated that
additional measures of efficiency may
assist with increasing market adoption
of heat pump water heaters. (A.O.
Smith, No. 51 at pp. 3–4) The CA IOUs
supported DOE’s tentative
determination to allow optional
efficiency representations at multiple
test conditions for heat pump water
heaters, stating that this change will
help consumers choose the heat pump
water heater that best suits their needs
and will aid in the maturation and
expansion of the heat pump water
heater market. (CA IOUs, No. 52 at pp.
1–2)
NEEA also supported DOE’s proposal
to allow for optional efficiency
representations at alternative ambient
conditions for heat pump water heaters
but encouraged DOE not to limit
condition representations based on the
specific type of heat pump. NEEA stated
that both split-system water heaters and
heat pump-only water heaters can be
designed for any combination of indoor,
outdoor, and semi-conditioned space
operation of the heat pump component.
Therefore, NEEA suggested that DOE
should not specify which metrics may
be reported on the basis of heat pump
type, as these additional representations
would not add any burden to
manufacturers because they are
optional. (NEEA, No. 56 at pp. 1–2)
A.O. Smith requested that DOE clarify
whether manufacturers may represent
optional metrics as consistent with
appendix E. (A.O. Smith, No. 51 at pp.
3–4)
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In response to NEEA’s comment, DOE
acknowledges that split-system and heat
pump-only water heaters may be
installed in a variety of configurations
which can vary the location of
components. For example, a heat pump
module (comprised of the compressor,
evaporator, and expansion devices)
could be installed either outdoors or in
a separate room indoors. Therefore, DOE
has updated the table of optional test
conditions in section 2.8 of appendix E
to reflect this fact by allowing splitsystem and heat pump-only water
heaters to be tested at the conditions
specified for any EX. In response to
NEEA and A.O. Smith, DOE notes that
manufacturers will be able to represent
optional metrics as specified in the
amended appendix E.
Rheem stated that the Code of Federal
Regulations only allows voluntary
ratings for distribution transformers and
commercial prerinse spray valves.
Rheem also stated that the 24-hour
simulated-use test for water heaters is
more complex and very different from
those specified for these other types of
equipment which, according to Rheem,
have test procedures that easily handle
testing at alternate conditions. (Rheem,
No. 47 at pp. 2–3)
In response to Rheem’s comment,
DOE notes that optional additional test
conditions are being adopted in
appendix E because industry has
already demonstrated its desire for them
through testing at specific conditions in
compliance with NEEA Advanced
Water Heating Specification v8.0. By
amending appendix E to include these
conditions, DOE is simply standardizing
current industry practices. Because
ratings at such conditions are voluntary,
DOE anticipates that there would be no
undue burden associated with adoption
of such provisions in this final rule.
DOE also notes that water heaters are
used in a variety of conditions and are
expected to operate at all times despite
them. This sets water heaters apart as
compared to what is expected of other
products (e.g., air conditioners), which
are only active and operate in response
to specific conditions. Test procedures
for these products already include a
range of conditions, and, therefore, they
do not require optional representations
of performance. For these other types of
products, the range of conditions
experienced would be narrower and
more predictable than the range of
conditions experienced by heat pump
water heaters,55 and, therefore, it is not
55 For example, Table 11 in section 3.6.1 of
appendix M1 to subpart B of 10 CFR part 430
provides the heating mode test conditions for
central (space-conditioning) heat pumps having a
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unduly burdensome to require testing at
multiple conditions for these other
types of products. The narrower range of
air conditions also ensures that the
results of testing are highly
representative of the product’s average
performance. This is not the case for
heat pump water heaters because of the
many different installation
configurations which are applicable to
heat pump water heaters—for instance,
some are located indoors, and some are
located outdoors. Allowing testing at
these conditions to be optional avoids
burdening manufacturers with test
conditions that may not apply to their
products. Using a different metric (EX)
for these conditions also ensures that
these representations are not read as
being valid for all consumer
applications; instead, the representation
is specific to the condition at which the
water heater is being tested.
AHRI, BWC, and Rheem suggested
that allowing optional ambient test
conditions may increase manufacturer
burden, arguing that they may
eventually be driven by the market to
conduct such testing. (AHRI, No. 55 at
p. 3; BWC, No. 48 at p. 2; Rheem, No.
47 at p. 3) BWC also stated that not all
manufacturers are currently conducting
testing per NEEA Advanced Water
Heating Specification v8.0, and that
DOE allowing optional testing based on
its test conditions would cause
significant burden. (BWC, No. 48 at p.
2) Rheem requested that DOE either
adopt the position from the last test
procedure rulemaking that requiring
additional testing at alternate conditions
is unduly burdensome or provide
justification for why it is not. (Rheem,
No. 47 at p. 3) AHRI indicated that
third-party laboratories may not be
equipped to perform the optional tests
at additional ambient conditions
because of how the test set-up differs
from that used in the standard test and
that large capital burdens would need to
be incurred in order to comply. AHRI
also expressed concern that DOE did not
adequately solicit manufacturer and
laboratory feedback on increased test
burden due to the proposed optional
additional ambient test conditions.
(AHRI, No. 55 at p. 4) Rheem also stated
that optional tests currently performed
by manufacturers are not necessarily
single-speed compressor and a fixed-speed indoor
blower. The range of temperatures at which the
outdoor evaporator coil can be tested is from 5 °F
at the lowest to 47 °F at the highest. Because a heat
pump water heater would also be active during the
summer months, DOE has determined that the
representative range of outdoor ambient
temperatures for a split-system heat pump water
heater’s outdoor evaporator coil could be from 5 °F
at the lowest to 95 °F at the highest.
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done to be in accordance with AWHS
and that NEEA, an entity which is not
a manufacturer, distributor, retailer, or
private labeler, was not restricted from
making representations of products
based on testing which did not use the
DOE test procedure. (Rheem, No. 47 at
pp. 2–3)
In response to these comments, DOE
disagrees that optional testing will
increase manufacturer burden for a
number of reasons. First, as previously
discussed in the July 2022 SNOPR, DOE
is currently aware of 17 water heater
brands represented in the Qualified
Products List for AWHS v8.0.
Participation in NEEA’s program using
Advanced Water Heating Specification
v8.0 requires manufacturers to submit
their own test results at the prescribed
test conditions; NEEA does not appear
to perform testing on behalf of
manufacturers, per its own
documentation.56 Most importantly,
DOE reiterates that this testing is
ultimately optional, so a manufacturer
may decline to undertake any additional
testing. Consequently, DOE has
concluded that allowing optional
additional testing conditions will not
increase burden for manufacturers.
BWC claimed that DOE is not
authorized under EPCA to allow
manufacturers to have additional
optional representations of performance
and requested that DOE clarify its
statutory authority. (BWC, No. 48 at p.
2) Rheem claimed that justifications for
other products allowing optional
additional ratings do not apply to
consumer water heaters and stated that
EPCA 57 can be interpreted as
prohibiting optional additional test
conditions that are not in the test
procedure.
In response to these comments, DOE
finds BWC’s and Rheem’s
interpretations of 42 U.S.C. 6293(c) to be
misguided. The statute requires
appliance efficiency testing and
representations to be done in
accordance with the DOE test
procedure. DOE routinely incorporates
by reference private sector testing
methods into Federal test procedures,
and nothing in the statute would
prohibit adoption of optional test
conditions as these commenters suggest.
56 Steps in the process flow for NEEA’s AWHS
Qualified Products List can be found online at:
neea.org/img/documents/qualified-productsprocess-flow.pdf (Last accessed on Sept. 10, 2022).
57 The commenter cited 42 U.S.C. 6293(c),
‘‘Restriction on Certain Representations,’’ of which
subsection (1) prohibits representations not made in
accordance with the currently applicable test
procedure and subsection (2) prohibits
representations not made in accordance with a new
or amended test procedure 180 days after the
adoption of that test procedure.
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DOE notes that the optional conditions
at which manufacturers may choose to
test their products are specified as part
of the AWHS v8.0 test procedure and
are not left up to manufacturers to
determine individually. Precisely by
including these optional conditions and
metrics in the appendix E test
procedure, DOE is permitting
manufacturers and other parties to make
such representations to the public in the
manner which the statute contemplates.
EPCA requires that a uniform efficiency
metric (i.e., UEF) be used to rate all
water heaters; however, the addition of
optional representations does not
prevent manufacturers from making its
mandatory UEF rating under the
required conditions. By virtue of the
new heat pump water heater testing and
metric being optional, DOE would not
enforce the required energy
conservation standard based upon
results of testing at optional test
conditions. Permitting testing under the
specified optional conditions may also
serve another purpose. In a future
rulemaking considering further
amendments to the appendix E test
procedure, DOE may consider adopting
multiple ambient test conditions for
certain types of water heaters, if data
from testing at these additional
conditions proves that this methodology
yields results more representative of
energy consumption over an average use
cycle. Hence, allowing manufacturers to
test and rate these optional conditions
would allow more data to be collected
for potential future amendments.
AHRI requested that DOE provide any
data justifying the proposal to include
optional ambient test conditions to
stakeholders. (AHRI, No. 55 at pp. 2–3)
BWC requested that DOE readopt its
position that there is insufficient data to
support optional additional ambient test
conditions and to provide the data that
caused DOE to make this proposal in the
SNOPR. (BWC, No. 48 at p. 2)
In response, DOE notes that NEEA’s
Qualified Products List 58 indicates the
climate-weighted average performance
of heat pump water heaters as tested by
manufacturers to the various conditions
in AWHS v8.0. (This performance
metric, ‘‘cool climate efficiency,’’ is a
result of testing under the optional
conditions which DOE is adopting in
this final rule.) From the data points in
NEEA’s Qualified Products List,
manufacturers demonstrate that heat
pump water heaters are less energyefficient at these additional conditions.
For example, Tier 4 products, which
58 Available at: www.neea.org/img/documents/
residential-unitary-HPWH-qualified-productslist.pdf (Last accessed on Sept. 18, 2022).
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range in UEF from 3.45 to 4.02 at DOE’s
required test conditions, have cool
climate efficiencies ranging from 3.1 to
3.5. These ratings have been provided to
NEEA by manufacturers conducting
their own testing. While DOE is not
adopting the cool climate efficiency
metric (because it requires testing at all
of the additional ambient conditions,
and that would significantly increase
burden for a manufacturer wanting to
provide consumers with additional
ratings), these cool climate efficiency
ratings are an objective indication of
how performance can be impacted by
varying climatic conditions. By
adopting EX optional ratings in
appendix E, DOE expects to facilitate
manufacturer testing and the generation
of relevant data related to water heater
performance at these additional
conditions. Again, the standardized
voluntary ratings could be considered in
a future rulemaking to determine the
representativeness of the current
mandatory ambient conditions in
appendix E.
AHRI also stated that DOE has not
provided evidence that NEEA’s AWHS
test conditions ensure repeatability and
reproducibility and suggested that these
requirements still apply even if the
procedure is optional. (AHRI, No. 55 at
p. 4)
Repeatability refers to the quality of a
test method which allows a laboratory
to achieve the same results when a
product is tested on more than one
occasion. Reproducibility refers to the
quality of a test method which allows
one laboratory to reproduce the results
obtained by another laboratory. Test
tolerances and set-up requirements are
essential to these parameters. As
proposed in the July 2022 SNOPR and
adopted in this final rule, the optional
test conditions would be tested per the
same tolerances and set-up
requirements as the current UEF test
procedure—simply at different
temperatures. Utilization of this Federal
testing framework makes it possible for
DOE to ensure that the voluntary ratings
of EX are repeatable and reproducible.
AHRI stated that DOE has not
provided references to other occasions
when it has adopted optional metrics for
voluntary representations for other
products or equipment. (AHRI, No. 55 at
p. 4) AHRI requested that DOE remove
the proposal concerning optional
additional ambient test conditions from
this rulemaking and instead address it
in a subsequent rulemaking for these
products. (AHRI, No. 55 at p. 4)
In response and as discussed earlier
in this section, DOE has previously
adopted optional metrics for voluntary
representations where there was a clear
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industry precedent for these metrics and
a consumer utility for having the
additional performance information.
Most recently, this was done for
dedicated outdoor air systems
(DOASes). For heat pump water heaters,
there is a clear indication that industry
wishes to provide consumers with these
additional ratings because numerous
product representations have been
submitted by several manufacturers to
NEEA for its Qualified Products List.
DOE’s amendment to officially adopt
these supplemental test conditions into
the appendix E test procedure ensures
that when these representations are
provided, they are done so based on a
consistent test method.
Rheem stated that it has not had
enough time to evaluate DOE’s proposal
to allow optional additional test
conditions. (Rheem, No. 47 at p. 2)
Rheem requested that DOE clarify the
sampling, certification, and enforcement
provisions for heat pump water heaters
with alternate representations. (Rheem,
No. 47 at p. 3)
In response, DOE notes that it
provided a three-week comment period
on the limited set of issues presented in
the July 2022 SNOPR, and other
commenters were able to assess DOE’s
latest proposal and provide substantive
comments during the time allotted. By
virtue of EX being an optional metric for
voluntary representations, DOE will not
require certification of EX
representations. Manufacturers who opt
to determine Ex must apply the
sampling requirements for determining
UEF in order to ensure consistency in
values provided to consumers.
Rheem recommended that DOE fully
evaluate the alternate conditions
specified in AWHS before adopting
them. (Rheem, No. 47 at p. 4) Rheem
stated that it has not had time to fully
evaluate the alternate test conditions
and questions whether they adequately
represent the entire Nation, or only
represent the Northwest, as these test
conditions were developed by NEEA.
(Rheem, No. 47 at p. 4)
To clarify, by allowing manufacturers
to make separate EX representations for
each set of test conditions, the voluntary
representations, individually, are not
designed to be representative of the
entire United States. To do so would
require these test conditions to be
averaged together based on prevalence
of climate conditions at a given location,
and this aspect of NEEA’s AWHS v8.0
is not being used in the appendix E
optional representations. Instead, it is
DOE’s mandatory testing scenario—the
determination of UEF through the
standard rating conditions—that is
intended to reflect average conditions
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for the Nation as a whole. DOE has
evaluated the full set of test conditions
NEEA specifies in AWHS v8.0 and has
determined that these conditions are
meant to cover the full range of
operating conditions (temperature and
humidity) possible across the United
States. They are not meant to only
represent the range of conditions
possible in the Northwestern United
States. The purpose of EX
representations, as employed by DOE at
appendix E, is to indicate performance
at individual rating points, which, along
with UEF, will provide additional
information to consumers.
Manufacturers will be permitted to
make voluntary representations at any
of the optional test conditions specified
in appendix E.
BWC stated that DOE’s proposal to
allow optional additional test
conditions would confuse consumers
and installers because they may not
have the means to sufficiently assess
environmental conditions where they
live. (BWC, No. 48 at p. 3) In addition,
BWC commented that allowing optional
additional test conditions may cause
scarcity of testing resources, thereby
significantly increasing manufacturer
burden. (BWC, No. 48 at p. 3)
DOE disagrees with BWC’s
presumption that consumers and
installers cannot assess environmental
conditions. These parties may easily
access a variety of sources of freely
available weather data, such as
information generated by the National
Oceanic and Atmospheric
Administration (NOAA) and the
National Weather Service (NWS).59 60 In
addition, installers of central air
conditioning, central heat pump, and
cool-climate heat pump units already
have sufficient access to local
environmental data required to install
them. These data are the same data
required for the installation of water
heaters. Although DOE understands
BWC’s concern regarding limited testing
resources, DOE once again reiterates
that this testing is ultimately optional;
manufacturers are not obligated to make
capital investments or dedicate testing
resources if it is not feasible. To the
extent that optional testing would
59 The National Weather Service (NWS) maintains
a Climate page on their website which provides past
weather records and climate information for regions
of the United States and its territories. This page is
available at: www.weather.gov/wrh/climate. (Last
accessed Sept. 28, 2022)
60 The National Centers for Environmental
Information (NCEI) maintains a Past Weather page
with past weather data from weather stations
around the world. This data is available for
download in various file formats. This page is
available at: www.ncei.noaa.gov/access/pastweather/. (Last accessed Sept. 28, 2022)
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utilize resources that would otherwise
be used for mandatory testing, DOE
notes that manufacturers would have
the option of foregoing or delaying
optional testing to accommodate
mandatory testing since DOE is not
requiring use of any of the optional test
conditions. Furthermore, as
manufacturers have already provided
ratings to NEEA at these alternate
conditions, DOE does not believe that
officially adopting these test conditions
would change overall available
laboratory capacity, especially as
manufacturers may opt to test these
optional conditions in-house.
ASAP, ACEEE, and NRDC requested
that DOE clarify which optional test
conditions would apply to split-system
water heaters with an indoor heat pump
component. (ASAP, ACEEE, and NRDC,
No. 54 at p. 2) In response, DOE notes
that the included optional test
conditions are intended to be used at
the discretion of the manufacturer.
Manufacturers are free to use the
conditions specified by the test points
they believe are most similar to what
their product may experience during
operation. For example, a manufacturer
of a split-system heat pump water heater
whose compressor and storage tank are
located outdoors and indoors,
respectively, may decide it would be
beneficial to evaluate the product’s
performance at an outdoor ambient
temperature of 34.0 °F. In this case, the
manufacturer would test the product
using the conditions specified by the E34
metric: outdoor dry-bulb temperature
and relative humidity of 34.0 °F and 72
percent, respectively, indoor dry-bulb
temperature and relative humidity of
67.5 °F and 50 percent, respectively, and
supply water temperature of 47.0 °F.
Rheem requested that DOE evaluate
wider tolerance ranges for the alternate
test conditions. Rheem also asked that
DOE clarify whether relative humidity
control is required for storage tanks
during split-system water heater tests, in
which case, the commenter argued that
two psychrometric chambers would be
required. (Rheem, No. 47 at pp. 3–4)
In response, DOE notes that the
amendments being adopted for ambient
condition tolerances during UEF testing
would also apply to EX testing, hence
allowing a similarly wider tolerance
range to apply at all conditions. When
testing a split-system heat pump water
heater or heat pump water heater
requiring a separate storage tank, the
heat pump portion of the system shall
be tested at the relative humidity
conditions specified, and the storage
tank can be tested at either the same
conditions or the conditions specified in
section 2.2.1 of appendix E. Thus, the
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relative humidity control is not required
for the storage tank during split-system
water heater tests. This is discussed
further in section III.D.1 of this
document.
Rheem requested that DOE remove
‘‘heat pump only’’ from the table of
alternate test conditions because they
are the same as the outdoor portion of
a split-system water heater. (Rheem, No.
47 at p. 4)
In response, DOE wishes to make
clear that circulating heat pump water
heaters (heat pump-only water heaters)
and split-system water heaters are not
identical. Circulating heat pump water
heaters are instantaneous-type units,
whereas split-system heat pump water
heaters have a storage tank and are,
overall, storage-type units. Both types of
products may have the heat pump
module located remotely from the
storage tank, but still indoors. In light of
this comment, DOE has modified the
table of alternate test conditions to
explicitly allow split-system and
circulating heat pump water heaters to
be tested at any of the conditions
specified.
D. Test Set-Up and Installation
1. Split-System Heat Pump Water
Heaters
In section III.A.2 of this document,
DOE discussed a new definition for this
subset of heat pump water heaters. As
established by this final rule, a ‘‘splitsystem heat pump water heater’’ means
a heat pump-type water heater with an
indoor storage tank and outdoor heat
pump component. In considering such
products, DOE had found that in a splitsystem heat pump, the heat pump part
of the system is typically installed
outdoors and, as a result, does not use
the indoor ambient air for water heating
directly. In the current appendix E test
procedure, different ambient conditions
are specified in appendix E for heat
pump water heaters and non-heat pump
water heaters, but there are no specific
conditions for split-system heat pump
water heaters.
In the January 2022 NOPR, DOE
proposed to specify that the heat pump
part of the system shall be tested using
the heat pump water heater dry-bulb
temperature and relative humidity
requirements, while the storage tank
part of the system shall be tested using
the non-heat pump water heater
ambient temperature and relative
humidity requirements. DOE noted that
the required non-heat pump water
heater ambient conditions can be met by
keeping the entire system within the
dry-bulb temperature and relative
humidity requirements for heat pump
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water heaters (i.e., both parts of the
system can be tested in the same
psychrometric chamber). 87 FR 1554,
1583 (Jan. 11, 2022).
On this topic, AHRI requested that
DOE clarify whether the proposed
testing requirements for split-system
heat pump water heaters would mean
testing would have to be carried out
with the heat pump and storage tank in
separate rooms. (AHRI, Jan, 27, 2022
Public Meeting Transcript, No. 27 at
p. 42) NYSERDA indicated that DOE
should collaborate with manufacturers
to ensure that test conditions and set-up
for split-system heat pump water
heaters are consistent, repeatable, and
not burdensome. (NYSERDA, No. 32 at
p. 4) BWC suggested that DOE should
permit manufacturers and testing
laboratories as much flexibility as
possible when determining the testing
locations of separate system
components and not prevent test set-ups
that can meet the specified conditions
for both systems in the same room or
area, if a manufacturer or test laboratory
so chooses. (BWC, No. 33 at p. 9) Rheem
requested clarification that the storage
tank can be tested at the heat pump test
conditions and still meet the
requirements of appendix E. (Rheem,
No. 31 at p. 3)
To reiterate DOE’s explanation in the
January 2022 NOPR, if a single room,
chamber, or area is capable of meeting
the dry-bulb temperature and relative
humidity requirements for heat pump
water heaters, then, like integrated heat
pump water heaters, split-system heat
pump water heaters can be tested with
both indoor and outdoor components in
the same space. In response to
NYSERDA, by adopting this approach,
DOE is aligning with the methodology
used already by industry when testing
heat pump water heater products for
other representations (such as the
Qualified Products List for NEEA’s
AWHS v8.0), so consequently, DOE
expects the results generated to be
consistent, repeatable, and not unduly
burdensome.
2. Mixing Valves
As discussed in section III.E.1 of this
final rule, there are certain water heater
designs which raise the temperature of
water stored in the tank significantly
above the outlet water temperature, and
these products are meant to be used
with a mixing valve (which may or may
not be provided with or built-in to the
unit) so that the hot stored water can be
tempered down to a more typical
delivery temperature. The January 2022
NOPR noted that the installation
instructions in section 4 of appendix E
do not address cases when a separate
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mixing valve should be installed. 87 FR
1554, 1580 (Jan. 11, 2022).
The January 2022 NOPR proposed to
incorporate instructions for separate
mixing valve installations based on
those found in the ENERGY STAR Test
Method to Validate Demand Response
for Connected Residential Water Heaters
(ENERGY STAR Connected Test
Method) (published on April 5, 2021).
This set-up requires installing the
mixing valve in accordance with the
water heater and mixing valve
manufacturer’s instructions. Absent
instruction from the water heater or
mixing valve manufacturer, the mixing
valve is to be installed in the outlet
water line, upstream of the outlet water
temperature measurement location, with
the cold water supplied from a tee
installed in the inlet water line,
downstream of the inlet water
temperature measurement location (i.e.,
the mixing valve and cold water tee are
installed within the inlet and outlet
water temperature measurement
locations). Section 4.1 of the ENERGY
STAR Connected Test Method further
clarifies that if the liquid flow rate and/
or mass measuring instrumentation is
installed on the outlet side of the water
heater, that it shall be installed after the
mixing valve. 87 FR 1554, 1580 (Jan. 11,
2022).
On July 18, 2022, EPA published the
ENERGY STAR Connected Residential
Water Heaters Test Method to Validate
Demand Response, Version 1.2.61 The
updated test method retains the same
instructions for setting up mixing valves
in section 4.1.
In response to the January 2022
NOPR, ASAP, ACEEE, and NCLC; AET;
A.O. Smith; and the CA IOUs supported
DOE’s proposal to include instructions
for the installation of a mixing valve.
(ASAP, ACEEE, and NCLC, No. 34 at pp.
1–2; AET, No. 29 at p. 2; A.O. Smith,
No. 37 at p. 4; CA IOUs, No. 36 at p.
4) A.O. Smith also commented that,
depending on the design, there may be
additional steps that are required (e.g.,
independently adjusting the tank
thermostat and the mixing valve settings
to remain in default mode per the
manufacturer’s instructions), and,
therefore, DOE should clarify the details
of this procedure. (A.O. Smith, No. 37
at p. 4)
In this final rule, DOE is adopting the
proposed installation instructions for
mixing valves as discussed in the
January 2022 NOPR. To the extent that
there may be additional steps required
to maintain normal operation with the
61 Available at: www.energystar.gov/products/
spec/residential_water_heaters_specification_
version_5_0_pd (Last accessed on July 25, 2022).
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mixing valve installed per the
manufacturer’s specifications, these
instructions would be heeded in
accordance with section 4.3 of the
amended appendix E test procedure. As
described in section III.E.1 of this
document, DOE is also providing an
optional test method for high storage
tank temperature operation, and this test
method involves the installation of
mixing valves for products which do not
come so equipped.
3. Flow Meter Location
The current test procedure does not
specify where in the flow path the flow
volume and density of water must be
measured, and this allows for laboratory
test set-ups to perform these
measurements either on the cold/inlet
side of the water heater or on the hot/
outlet side. As discussed in this
rulemaking, water mass calculations can
account for the difference in the density
of water at the inlet vs. the outlet (colder
water at the inlet has a higher density);
however, there could be cases when a
measurement based on the inlet location
could result in inaccurate mass
calculations. Specifically, some of the
mass of inlet water could, after being
heated, expand out of the water heater
into the expansion tank and be purged
prior to a draw. Any ‘‘expanded’’
volume of water that is lost through the
bypass (purge) line could be included in
a volume measurement taken at the
inlet, but not be included in a volume
measurement taken at the outlet. 87 FR
1554, 1581 (Jan. 11, 2022). The
Department requested information and
data regarding the issue of flow meter
location (inlet vs. outlet) in the April
2020 RFI and the January 2022 NOPR.
85 FR 21104, 21113 (April 16, 2020); 87
FR 1554, 1581 (Jan. 11, 2022).
In response to the April 2020 RFI,
four commenters either disagreed with
requiring the flow meter to be located at
the outlet or requested that DOE
continue to allow facilities to choose the
location, whereas two commenters
stated that the flow rate should be
measured at the outlet of the water
heater, expressing concern that
measuring at the inlet may be
inaccurate. 87 FR 1554, 1581 (Jan. 11,
2022). The January 2022 NOPR
presented DOE’s exploratory test data
evaluating the effect of flow meter
location on the water mass
measurement (see Table III.2 of the
January 2022 NOPR). DOE’s testing
using Coriolis flow meters on both the
inlet and outlet water lines indicated
that more accurate measurements of the
mass of water delivered are obtained
when the flow meter is located in the
outlet water line than when located on
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the inlet line, when both results were
compared to a mass scale.62 In
particular, the error in the UEF resulting
from a mass measurement from a flow
meter at the outlet ranged between 0.002
and 0.016, whereas the error in the UEF
resulting from a mass measurement
from a flow meter at the inlet ranged
between 0.023 and 0.029, depending on
the type of water heater (with DOE
testing both gas-fired storage and gasfired instantaneous water heaters). DOE
also acknowledged that third party
laboratories typically install a flow
meter on the inlet side. However, DOE
did not propose a change based on this
limited set of test results, which only
included one gas-fired storage water
heater sample and one gas-fired
instantaneous water heater sample, and
stated that more test data are required.
Id. at 87 FR1581–1582.
In response to the NOPR’s request for
information on this issue, AHRI stated
that having the flow meter at the inlet
of the water heater avoids having debris
damage the flow meters (e.g., Teflon
tape debris from the test rig can end up
in the flow meter and cause damage). In
addition, AHRI commented that placing
the flow meter at the outlet may cause
water mass calculation problems,
because the temperature variation is
greater at the outlet, and flow meters
may not be designed to withstand these
higher outlet water temperatures.
Therefore, AHRI indicated it would
support the option of installing a flow
meter at the inlet. (AHRI, No. 40 at
p. 2) Rheem once again noted that major
third-party testing laboratories have
flow meters installed at the inlet of the
water heater and that it is likely that all
certified models have been tested with
such a set-up. (Rheem, No. 31 at pp. 4–
5) BWC commented that manufacturers
should still have the option to install
flow meters at the inlet to ensure
accurate results and longevity of testing
equipment, as well as to avoid
manufacturer burden. Specifically, BWC
indicated that manufacturers may have
sophisticated set-ups with flow meters
installed at the inlet, and there could be
substantial burden with overhauling
these set-ups. (BWC, No. 33 at p. 8)
Based on these comments, DOE has
determined that a requirement for flow
meters to be installed at the outlet may
not only require re-testing a large
number of basic models but also
62 Mass of water drawn from the water heater can
either be directly measured using a mass scale, or
it can be calculated by using a flow meter to
measure the volume of water moved (and converted
to mass using the density of the water). The mass
scale approach represents the actual value of the
mass of water drawn, against which the flow meter
results can be compared.
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potentially degrade the reliability of the
testing rig due to debris flowing
downstream. Because there is a
generally consensus among stakeholders
who commented on this issue that it is
necessary to retain the ability to install
the flow meter at the inlet side, DOE is
not amending appendix E to require
measurement at the outlet side. Instead,
DOE is maintaining its current
provisions in sections 3 and 4 of
appendix E, which allow for the flow
meter to be installed on either the inlet
or outlet side.
4. Separate Storage Tanks
Some water heaters on the market
require a volume of water, typically
contained in either a storage tank (or
tanks) or in a piping distribution system
of sufficient volume, to operate. These
products operate by circulating water
stored either in the piping system or
from a separate tank (or multiple
separate tanks) to the water heater to be
heated then back to the piping system
or tank until hot water is needed. As
discussed in section III.A.4.a of this
document, DOE is adopting a definition
for these products, which are termed
‘‘circulating water heaters.’’ In the
January 2022 NOPR, DOE identified two
types of circulating water heater
products that require a volume of water
to operate—heat pump-only water
heaters that require installation with a
separate storage tank and circulating
gas-fired instantaneous water heaters
that require installation with a separate
storage tank or a piping system of
sufficient volume. 87 FR 1554, 1583–
1585 (Jan. 11, 2022). Circulating gasfired instantaneous water heaters are
distinct from other types of gas-fired
instantaneous water heaters in that they
are not designed to operate independent
of a storage tank or hot water system, as
other gas-fired instantaneous water
heaters are. This applies generally to
circulating water heaters; however, DOE
has determined that there are no electric
resistance or oil-fired circulating water
heaters on the market today.
The currently applicable appendix E
test procedure does not have procedures
in place to appropriately test circulating
water heaters. In the January 2022
NOPR, DOE proposed to require that
circulating water heaters be tested using
an 80 gallon (±1 gallon) unfired hot
water storage tank (UFHWST) that
meets the energy conservation standards
for an unfired hot water storage tank at
10 CFR 431.110(a). 87 FR 1554, 1583–
1585 (Jan. 11, 2022).
In response to the January 2022
NOPR, DOE received a number of
comments regarding the separate storage
tank requirements, primarily related to
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the ±1 gallon tolerance, the
representativeness of an 80-gallon
unfired hot water storage tank, and the
lack of a specification of an upper
bound on thermal insulation for the
unfired hot water storage tank. These
comments were discussed in detail and
addressed in the July 2022 SNOPR.
Some commenters specifically
recommended that DOE specify electric
storage water heaters to be paired with
heat pump-only water heaters.
Commenters also raised questions as to
whether or not the separate tanks to be
used during testing may have back-up
heating. For gas-fired circulating water
heaters, commenters urged DOE to
consider allowing multiple tank sizes to
be used for testing rather than just the
80-gallon tank proposed in the January
2022 NOPR. 87 FR 42270, 42281–42283
(July 14, 2022).
After considering the issues raised by
commenters responding to the January
2022 NOPR, in the July 2022 SNOPR,
DOE proposed several updates to its
earlier proposals (in section 4.10 of
appendix E) for testing circulating water
heaters as initially presented in the
January 2022 NOPR. 87 FR 42270,
42282–42283 (July 14, 2022). These
proposed modifications to DOE’s initial
proposal are set forth in the paragraphs
that follow.
After re-evaluating the market for
heat-pump-only water heaters, DOE
tentatively determined that testing such
products with a conventional electric
storage water (i.e., an electric water
heater that uses only electric resistance
heating elements) would be more
representative than testing with an
UFHWST. Therefore, DOE proposed
that heat-pump-only water heaters be
tested in the medium draw pattern
using a 40-gallon traditional electric
storage tank (i.e., that provides heat only
with electric resistance heating
elements) that has a UEF rating at the
minimum required at 10 CFR 430.32(d).
DOE chose a 40-gallon tank in the
medium draw pattern because that size
and draw pattern combination has the
highest number of models currently
available on the market.63 DOE also
proposed that, for heat pump-only water
heaters, the test be carried out using a
tank that does not ‘‘over-heat’’ the
stored water (i.e., Tmax,1 (maximum
measured mean tank temperature after
cut-out following the first draw of the
24-hour simulated-use test) must be less
than or equal to Tdel,2 (average outlet
water temperature during the 2nd draw
63 See Figure 3A.2.8 of the Preliminary Analysis
Technical Support Document for consumer water
heaters (Docket No. EERE–2017–BT–STD–0019–
0018).
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of the 24-hour simulated-use test); see
section III.E.1 of this document for more
discussion of water heater ‘‘overheating’’). This would ensure that the
electric storage tanks are not
overheating during the test, thereby
ensuring consistency across tests. 87 FR
42270, 42282 (July 14, 2022).
By contrast, DOE maintained its
earlier proposal that a UFHWST be used
for testing of circulating gas-fired water
heaters, as those products are more
likely to be installed with a UFHWST in
the field. Therefore, DOE tentatively
concluded that testing with an
UFHWST would be representative for
such units. 87 FR 42270, 42282 (July 14,
2022).
In response to the January 2022
NOPR, some commenters suggested that
DOE allow manufacturers to specify the
storage tank used for testing. DOE noted
that this approach could lead to
additional test burden for third-party
testing laboratories, which may need to
acquire more than one storage tank if
they are performing tests for multiple
manufacturers, each of whom may
specify a different storage tank for
testing. In order to avoid creating the
potential for additional test burden,
DOE tentatively determined not to allow
manufacturers to specify the electric
storage water heater or unfired hot water
storage tank used respectively for testing
the heat pump-only or gas-fired
instantaneous circulating water heaters.
Additionally, DOE stated it would
consider relevant amendments to
certification and reporting requirements
in a separate rulemaking. 87 FR 42270,
42282 (July 14, 2022).
After considering the comments
regarding the tolerance on the storage
tank initially proposed in the January
2022 NOPR, DOE tentatively
determined in the July 2022 SNOPR that
a wider tolerance would reduce
potential testing burden while still
providing representative and
reproducible results. Specifically, DOE
tentatively concluded that a 10-percent
tolerance would increase flexibility for
manufacturers by increasing the number
of tanks that could be used for testing,
while not materially impacting the UEF
test results. Therefore, consistent with
the recommendations provided by
commenters, DOE proposed to adopt a
10 percent tolerance (±10 percent,
allowing products with rated storage
volumes between 36 gallons and 44
gallons) for the electric storage water
heater used for testing heat-pump-only
water heaters. 87 FR 42270, 42282 (July
14, 2022).
Additionally, after further review of
the market for circulating gas-fired
instantaneous water heaters and unfired
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hot water storage tanks, DOE proposed
in the July 2022 SNOPR to allow testing
with a tank at any storage volume
between 80- and 120-gallons. Based on
further analysis, DOE tentatively
determined that variations in the tank
size should not significantly impact the
result of the test. During a water draw,
the internal tank temperature decreases
as hot water exits the tank and is
replenished by colder water entering the
tank. Generally, different tank sizes will
result in different rates of internal
temperature decrease during a water
draw (e.g., during a specified water
draw, a smaller tank will generally
experience a faster decrease in
temperature compared to a larger tank).
During a test, any potential differences
in the tank water temperature due to the
use of different size tanks would be
accompanied by a corresponding
proportional difference in burner ontime, such that the impact on measured
efficiency (i.e., the ratio of energy output
to energy input) would be negligible.
DOE noted its recognition that a larger
tank would likely have more standby
losses than a smaller tank; however,
DOE tentatively determined that the
impact this would have on measure
efficiency would also not be significant.
87 FR 42270, 42282–42283 (July 14,
2022).
DOE noted that providing a range of
allowable tank volumes would reduce
potential burden by providing
manufacturers with more tank options,
thereby allowing them to pair their
circulating gas-fired instantaneous water
heaters with an existing UFHWST
model. This approach is also likely to be
more representative of how the units
would be installed in the field as
opposed to testing with a custom-made
tank for testing or a competitor’s tank
that meets a specific volume
requirement. 87 FR 42270, 42283 (July
14, 2022).
In addition, after considering
comments in response to the January
2022 NOPR, DOE tentatively
determined in the July 2022 SNOPR that
the lack of an upper bound on the
thermal insulation value for the
UFHWST could lead to differences in
measured efficiency that reflect
differences in tank performance, rather
than reflecting differences in water
heater performance. Therefore, DOE
tentatively determined that more
specific constraints on tank performance
are warranted to ensure more
comparable test results across the
subject water heater models. DOE
proposed to require that UFHWSTs used
for testing circulating gas-fired
instantaneous water heaters exactly
meet the baseline energy conservation
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standard for UFHWSTs.64 87 FR 42270,
42283 (July 14, 2022). However, DOE
did not include commenters’ suggested
specifications for other tank
characteristics (such as the inlet and
outlet connection locations, internal
tank baffling, and inlet tube designs) for
the UFHWST because, as explained in
the July 2022 SNOPR, DOE tentatively
determined that over-specifying the
design of the UFHWST—given the
impacts on the UEF rating are
minimal—could result in a very narrow
range of UFHWST models which could
be used for testing circulating water
heaters, thereby potentially introducing
significant barriers to testing these
products at third-party laboratories. In
addition, DOE tentatively concluded
that it lacked sufficient information
regarding these specifications to do so.
87 FR 42270, 42283 (July 14, 2022).
Similarly, DOE proposed that the
electric storage water heater used for
testing heat-pump-only water heaters
have a rated UEF corresponding to the
minimum standard found at 10 CFR
430.32(d), thereby helping to ensure
more comparable results.
In summary, in the July 2022 SNOPR,
DOE proposed to further amend the
separate storage tank requirements
proposed in the January 2022 NOPR for
heat pump-only and gas-fired
circulating water heaters. DOE proposed
that heat pump-only water heaters be
tested with a 40-gallon (±4 gallons)
electric storage water heater that has a
UEF value corresponding to the
minimum standard for such products
and that does not ‘‘over-heat’’; and that
gas-fired circulating water heaters be
tested with an 80-gallon to 120-gallon
unfired hot water storage tank that is
rated equal to the energy conservation
standard for such equipment.
In response to the July 2022 SNOPR,
NEEA indicated support for DOE’s
revisions to the proposed test procedure
for circulating water heaters. (NEEA,
No. 56 at p. 2) A.O. Smith and the CA
IOUs supported DOE’s proposal
requiring gas-fired circulating water
heaters to be tested using a UFHWST
with a storage volume between 80 and
120 gallons and an R-value exactly at
the minimum R-value required at 10
CFR 431.110(a). (A.O. Smith, No. 51 at
p. 8; CA IOUs, No. 52 at p. 6) The CA
IOUs also indicated support for the
revision to require heat pump
circulating water heaters to use a 40gallon electric resistance water heater
meeting the minimum UEF
requirements. (CA IOUs, No. 52 at p. 6)
64 Currently, baseline energy conservation
standards for UFHWSTs require a thermal
insulation of R–12.5. 10 CFR 431.110(a).
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AHRI stated that allowing
manufacturers to specify the storage
tank used for testing circulating water
heaters would not increase test burden
for third-party laboratories because
manufacturers would provide both the
water heater and the storage tank it was
designed to be used with to the
laboratories. (AHRI, No. 55 at pp. 5–6)
BWC suggested that the capacity range
of 80 to 120 gallons for UFHWSTs used
to test circulating water heaters is too
wide to ensure consistent results, so,
therefore, the commenter requested that
DOE complete further testing to validate
it. (BWC, No. 48 at p. 4)
After considering these comments,
DOE has concluded that providing a
range of allowable tank volumes for use
with circulating gas-fired instantaneous
water heaters as described in the July
2022 SNOPR would reduce potential
burden by providing manufacturers
with more tank options, thereby
allowing them to pair their circulating
gas-fired instantaneous water heaters
with an existing UFHWST model. This
approach balances manufacturer burden
(by allowing flexibility in the tank size)
with ensuring reproducibility of test
results (by limiting the options to a
fixed range of sizes). In response to
AHRI’s comments, DOE notes that it is
not adopting changes to the certification
requirements in this final rule, and
whether or not manufacturers may
specify a specific model of UFHWST is
an issue out of the scope of this test
procedure rulemaking and will be
addressed in a future rulemaking
addressing certification requirements for
consumer water heaters.
As such, in this final rule, DOE is
adopting the separate storage tank
requirements for circulating gas-fired
instantaneous water heaters as proposed
in the July 2022 SNOPR. In response to
BWC’s comment, DOE understands that
the choice of tank size may result in
slightly different ratings for these
products, and BWC seeks to determine
how much variability in results there
would be if testing were to be conducted
with an 80-gallon UFHWST versus a
120-gallon UFHWST. However, the
Department’s approach is instead to
permit manufacturers some flexibility in
testing options so as to be able to tailor
the tank pairing to the design or
application intent of the circulating
water heater, and to then subsequently
account for the variation in ratings
when setting amended standards for
circulating water heaters by having the
required UEF be a function of the
effective volume. As discussed in
section III.I of this document,
compliance with the separate storage
tank test method will not be required
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until compliance with amended energy
conservation standards is mandatory, if
such standards are adopted.
Additionally, section III.F.2.b of this
document describes the use of the
effective storage volume metric to be
able to associate efficiency ratings to the
storage tank size for circulating water
heaters. This matter is discussed further
in this section in response to other
comments. In taking these steps, DOE
can, in the ongoing standards
rulemaking for consumer water heaters,
propose and request comment on new
energy conservation standards for
circulating water heaters that are
functions of the effective storage
volume.
SMTI requested that DOE widen the
accepted volume range for electric
storage tanks used to test separate heat
pump-only water heaters based on the
performance requirements of each
product instead of requiring that all
products be tested with a 40-gallon tank.
(SMTI, No. 49 at p. 1) SMTI suggested
that heat pump-only water heaters be
tested with manufacturer-specified
storage tanks, which the manufacturer
would provide to third-party
laboratories, and that a 40-gallon tank be
used if a specific storage tank is not
specified. (SMTI, No. 49 at p. 2) A.O.
Smith stated that there is insufficient
data to conclude that the 40-gallon
electric resistance water heater should
be used for testing heat-pump-only or
split-system water heaters and that a 50gallon electric resistance water heater
may be more representative based on
manufacturer data. (A.O. Smith, No. 51
at p. 9) However, A.O. Smith did not
provide any manufacturer data to
support its claim that a 50-gallon
electric resistance water heater would
be more representative.
As described in the July 2022 SNOPR,
DOE selected a 40-gallon tank in the
medium draw pattern because that size
and draw pattern combination has the
highest number of models currently
available on the market as observed in
models currently certified to DOE’s
Compliance Certification Database (see
Figure 3A.2.8 of Preliminary Analysis
TSD). 87 FR 42270, 42282 (July 14,
2022). This finding has not changed
since the publication of the July 2022
SNOPR, and on this basis (because
additional data were not provided by
stakeholders), DOE has concluded that
this tank size and draw pattern are the
most representative choice to be paired
with a heat pump-only water heater. In
response to SMTI’s request to widen the
volume range, DOE has determined to
adopt a volume tolerance of ±5 gallons,
as opposed to ±10% (4 gallons) which
was proposed in the July 2022 SNOPR.
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This change is based on further
inspection of the rated storage volumes
of electric storage water heaters which
have a nominal capacity of ‘‘40 gallons’’
as observed in models certified to DOE’s
Compliance Certification Database. As
such, DOE does not expect the
difference to be substantial in impacting
energy efficiency results for circulating
heat pump water heaters because the
volume range covers products of the
same nominal volume. As previously
stated in response to a comment made
by AHRI, DOE is allowing
manufacturers to specify an effective
storage volume for the tank rather than
a specific model because any
characteristics of the tank that would
affect the efficiency rating of the
circulating water heater during a test are
accounted for in the volume and
efficiency rating (in this case, UEF) of
the tank.
AHRI and BWC indicated that DOE’s
primary TSD for energy conservation
standards for consumer water heaters
suggests that the 40-gallon electric
resistance water heaters used to test
heat-pump-only water heaters may be
phased out by future DOE regulations.
(AHRI, No. 55 at p. 5; BWC, No. 48 at
pp. 4–5) Rheem supported AHRI’s
comment on this issue. (Rheem, No. 47
at p. 5)
In response, DOE notes that the
current energy conservation standards
rulemaking for consumer water heaters
is still ongoing, and any preliminary
results published as part of that
rulemaking are neither final nor binding
in any way. Consequently, it is not
confirmed that electric resistance
storage water heaters will be phased out.
Nevertheless, to ensure there will be no
confusion in the event such regulatory
changes were to occur, DOE is removing
the requirement that the storage tank
use only electric resistance heating
elements. Accordingly, the associated
portion of section 4.10 of appendix E
has been updated to read as follows:
‘‘When testing a heat pump
circulating water heater, the tank to be
used for testing shall be an electric
storage water heater that has a measured
volume of 40 gallons (±5 gallons), has a
First-Hour Rating greater than or equal
to 51 gallons and less than 75 gallons
resulting in classification under the
medium draw pattern, and has a rated
UEF equal to the minimum UEF
standard specified at 10 CFR 430.32(d),
rounded to the nearest 0.01. The
operational mode of the heat pump
circulating water heater and storage
water heater paired system shall be set
in accordance with section 5.1.1 of this
appendix.’’
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In its comments on the July 2022
SNOPR, A.O. Smith supported ensuring
that non-unitary heat pump water
heaters 65 intended for use in a
single-family home or an individual
dwelling unit that need to be paired
with a separate storage tank are tested
and certified to the Department
consistent with appendix E. (A.O.
Smith, No. 51 at pp. 8–9) A.O. Smith
also requested that DOE clearly define
the test apparatus for heat pump
circulating water heaters. (A.O. Smith,
No. 51 at p. 9)
In response to concern from certain
stakeholders, DOE will allow
manufacturers of gas-fired circulating
water heaters to represent thermal
efficiency test results measured
according to the commercial water
heaters test procedure outlined at 10
CFR part 431, subpart G, in addition to
the required UEF test results. DOE also
notes that this final rule clearly defines
the test apparatus for circulating heat
pump water heaters in section 4.10 of
the amended appendix E.
Rheem reiterated its request for
clarification as to whether a system (i.e.,
a heat pump and storage tank designed
to be used together) can be certified
independent of the proposed method to
use a specific storage tank or electric
resistance water heater. (Rheem, No. 47
at p. 5) Rheem also requested that DOE
address whether a split-system water
heater, designed to be used with an 80gallon tank, can have a storage tank with
electric resistance elements and whether
a replacement tank can be sold. (Rheem,
No. 47 at p. 5)
In response to Rheem, DOE would
clarify that a product which consists of
a heat pump and a storage tank designed
to be used together and are sold together
would constitute a ‘‘split-system heat
pump water heater.’’ Such a system
would be certified altogether as an
electric storage water heater, and there
would be no need to use the test
procedure provisions for a separate
storage tank. If the heat pump module
were sold separately and independent of
the tank, then it would constitute a
‘‘circulating heat pump water heater,’’
and the test procedure provisions for a
40-gallon ±5 gallon separate storage
water heater would then apply. In
Rheem’s example of a product with an
80-gallon storage tank, that
configuration would constitute a ‘‘split65 DOE understands ‘‘non-unitary heat pump
water heaters’’ to refer to products which consist of
a heat pump system to heat water but are not
packaged with the rest of the components used in
domestic hot water production (i.e., a hot water
storage tank). These products are considered
circulating heat pump water heaters in this
rulemaking.
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system heat pump water heater’’—an
electric storage water heater with a
storage volume of 80 gallons. The
separate storage tank provisions do not
apply to such a product. The 80-gallon
storage tank component of the splitsystem heat pump water heater may
have electric resistance back-up
elements. Replacement storage tanks
sold on a separate basis—essentially an
electric resistance water heater with a
storage volume of 80-gallons—would
not be permitted, because electric
resistance heating elements would not
be able to achieve the UEF energy
conservation standard levels mandatory
for electric storage water heaters greater
than 55 gallons for which compliance is
currently required (see 10 CFR
430.32(d)).
In response to the January 2022
NOPR, A.O. Smith also commented that
the energy from a circulating pump
should be used in the UEF calculations
and that the flow rates between the
circulating heat pump water heater and
the storage tank should be specified by
the manufacturer. (A.O. Smith, No. 37 at
p. 3) DOE agrees that including the
energy use of the circulating pump is
appropriate and consistent with the
currently applicable appendix E test
procedure, which requires measurement
of power consumption of auxiliary
electricity-using components. In this
final rule, for water heaters which
require separate storage tanks, the
power consumption of the circulating
pump shall be directly metered if the
pump is integrated into the water
heater. Section 4.10 of the amended
appendix E test procedure will require
that if the water heater is supplied with
a separate, non-integrated circulating
pump, it is to be installed as per the
manufacturer’s installation instructions,
and its power consumption will
similarly be accounted for in the energy
measurements to determine UEF.
In conclusion, after considering
comments received in response to the
January 2022 NOPR and the July 2022
SNOPR, DOE is adopting the
requirements for separate storage tanks
as discussed in this final rule.
DOE’s previous proposals involving
the use of separate storage tanks did not
specify a test procedure by which the
storage volume of unfired hot water
storage tanks paired with circulating
water heaters to determine efficiency is
to be measured. It is important to obtain
a precise measurement of the storage
volume of the UFHWST because its
physical size affects the measured
efficiency of the water heater due to
standby losses of heat from the stored
water to the air surrounding the storage
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tank; these standby losses increase as
the size of the tank increases.
To ensure the accuracy and
repeatability of test results, DOE is
amending sections 4.10 and 5.2.1 of
appendix E so that the method for
determining storage tank volume
specified in section 5.2.1 must also be
conducted to verify the volume of
unfired hot water storage tanks used to
test circulating water heaters. In this
method, storage volume is determined
in gallons by subtracting the tare weight,
measured while the tank is dry and
empty, from the weight of the system
when filled with water and dividing the
resulting net weight of water by the
density of water at the measured water
temperature. This method is consistent
with how the volume of unfired hot
water storage tanks is currently rated. It
is also the method specified for storagetype and storage-type instantaneous
commercial water heaters under subpart
G to 10 CFR part 431.
Additionally, as discussed in section
III.F.2.b of this document, DOE is
establishing that the effective storage
volume of a circulating water heater is
equivalent to the measured storage
volume of the separate storage tank
which was used during testing of the
circulating water heater. This alleviates
the manufacturers’ concerns by ensuring
that the standby losses reflected in the
UEF rating of the circulating water
heater can be mapped to the volume of
the separate storage tank which was
used during testing without having to
specify a particular model of tank, for
example. DOE would consider this tank
volume in the development of energy
conservation standards for circulating
water heaters.
E. Test Conduct
As discussed throughout this
rulemaking, EPCA requires that any test
procedures prescribed or amended
under this section shall be reasonably
designed to produce test results which
measure energy efficiency, energy use,
or estimated annual operating cost of a
covered product during a representative
average use cycle (as determined by the
Secretary) or period of use and shall not
be unduly burdensome to conduct. (42
U.S.C. 6293(b)(3)) The proposed
changes to test conduct, along with
specific stakeholder comments received
and DOE’s responses, are discussed
further in the subsections that
immediately follow.
1. High Temperature Testing
Certain electric storage water heaters
on the market are capable of raising the
temperature of the stored water
significantly above the outlet water
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temperature requirements specified in
section 2.4 of appendix E, while still
delivering water at a lower temperature
that is at or near the temperature
specified in appendix E. The storage
tank is heated to a temperature which is
still within the normal operating range
of the water heater, but a mixing valve
is typically installed with these
products (either integrated into the
water heater by the manufacturer at the
factory, or added to the water heater in
the field by the installer) to temper the
outlet water to a more typical delivery
temperature. (Set-up requirements for
mixing valves that are to be used during
testing are discussed in section III.D.2 of
this final rule.) When the outlet water is
tempered like this, a smaller amount of
the hot water from the tank is required
to meet demand (because the water in
the tank is hotter than desired). Because
less water needs to be removed from the
tank, the effect of a mixing valve is to
increase the amount of hot water that
can be delivered overall by the water
heater. In addition to determining the
set-up considerations to test these
products in a representative manner,
DOE must consider the impact of raising
the storage tank temperature
significantly above the setpoint outlet
temperature (i.e., ‘‘storage tank
overheating’’) on the efficiency of a
water heater since this represents how
the water heater will be used in the
field.
As discussed in the July 2022 SNOPR,
storage tank overheating increases the
amount of hot water that a given size
water heater can deliver. 87 FR 42270,
42277–42278 (July 14, 2022).
Historically, it has not been
uncommon for water heaters to come
with the capability to adjust the settings
to increase the temperature of the water
being stored in the tank, although, it is
DOE’s understanding that in the past,
consumers rarely modified the
preconfigured settings on their storage
tanks. However, DOE has recently
become aware of products that are being
marketed to consumers with ‘‘capacity
boosting’’ capabilities so as to avoid the
need to install a larger storage-type
water heater. The products (that DOE
addressed in the July 2022 SNOPR) are
equipped with user-operable modes
which set the water heater to boost the
storage tank temperature and use a
built-in mixing valve (or one installed at
the point of manufacture) to
automatically maintain the delivery
temperature. For example, one
manufacturer produces 30-, 40-, and 50gallon water heaters with an ‘‘X-High
Setting’’ claiming to provide the same
amount of hot water (‘‘Effective
Capacity,’’ as the manufacturer refers to
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it) as significantly larger water heaters
with a more typical storage tank
temperature of 125 °F—such as an 80gallon capacity for the 50-gallon model,
64-gallon capacity for the 40-gallon
model, and 48-gallon capacity for the
30-gallon model.66 DOE notes that the
40-gallon model and the 50-gallon
model are capable of providing effective
capacities greater than 55 gallons,
which, based on effective capacity,
would put these models into a different
product class. (see 10 CFR 430.32(d)).
Another manufacturer produces a 55gallon water heater with a variety of
settings allowing the user to get
‘‘performance equivalency’’ of a 65-, 80, or 100-gallon tank, stating that the tank
raises the temperature safely up to
170 °F.67 Again, these increased
capacities would put this model into a
different product class.
As stated in the July 2022 SNOPR,
consumers would be expected to use the
over-heated mode as part of the regular
operation of their water heater.
Accordingly, for such products, DOE
expects that a representative average use
cycle would include some portion of
time in over-heated mode. 87 FR 42270,
42279 (July 14, 2022). For these water
heaters, DOE believes that a
representative average use cycle in the
test procedure must encompass the
’’capacity boosting’’ capability, as this is
the mode that DOE believes the
consumer will likely be using once
installed in the field, because such
purchases are likely predicated on this
capacity-boosting capability.
The operational mode selection
instructions in section 5.1 of appendix
E do not specifically address the
situation when a water heater has this
type of operational mode that boosts the
capacity. In response to the January
2022 NOPR, several commenters
requested that DOE consider
amendments to the appendix E test
procedure to provide more
representative efficiency results
(including ways to account for the
increased effective capacity) for these
products that ‘‘overheat’’ the stored
water beyond the delivery temperature.
After considering these comments in the
July 2022 SNOPR, DOE proposed to
establish additional requirements for the
testing of water heaters which have
these operational modes. 87 FR 42270,
42278 (July 14, 2022).
66 See, for example: www.geappliances.com/
appliance/GE-Smart-50-Gallon-Electric-WaterHeater-with-Flexible-Capacity-GE50S10BMM (Last
accessed April 14, 2023).
67 For example, DOE’s Compliance Certification
Database includes a 107-gallon electric storage
water heater with an FHR of 94 gallons.
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In order to further examine the
potential impacts of storing water at
temperatures higher than the delivery
temperature, DOE performed testing on
one 50-gallon electric resistance storage
water heater that includes a built-in
mixing valve and multiple userselectable modes to boost the delivery
capacity through storage tank
overheating. As described in the July
2022 SNOPR, DOE collected data at
three different storage tank
temperatures, each of which provided
an outlet water temperature at 125 °F
±5 °F through the use of the built-in
mixing valve. DOE compared the
maximum measured mean tank
temperature after cut-out following the
first draw of the 24-hour simulated-use
test (Tmax,1) to the average outlet water
temperature during the second draw
(Tdel,2) as an indicator of the degree of
‘‘overheating.’’ DOE’s test data is
provided in Table III.3 of the July 2022
SNOPR. 87 FR 42270, 42278–42279
(July 14, 2022).
The test results indicated that storage
tank overheating clearly leads to an
increase in the measured FHR value.
The test configuration corresponding to
the current DOE test procedure
produced an FHR value of 77 gallons.
The overheated configurations with
mean tank temperatures of 144.5 and
159.6 produced FHR values of 81 and 95
gallons, respectively. DOE notes that an
FHR of 95 gallons is comparable to that
of a 100-gallon electric storage water
heater.68 However, increasing the
temperature of the stored water can
reduce energy efficiency because the
hotter tank undergoes substantially
higher standby energy losses. As shown
in Table III.3 of the July 2022 SNOPR,
DOE’s test data show that at a tank
temperature of 124.3 °F, the measured
UEF is 0.94, which is compliant with
the current standards. When the
temperature is increased to 144.5 °F, the
UEF decreases to 0.90. Further
increasing the temperature to 159.6 °F
decreases the UEF to 0.88. 87 FR 42270,
42279 (July 14, 2022).
All of the tested temperatures
correspond to normal operational modes
for the water heater, and a review of
publicly-available product literature
indicates that products that utilize
storage tank overheating generally offer
user-selectable operational modes that
result in stored water temperatures
ranging from 100 °F to 170 °F.
Consumers who choose to use a highcapacity (i.e., ‘‘overheated’’) mode will
experience the water heater performing
68 For example, DOE’s Compliance Certification
Database includes a 107-gallon electric storage
water heater with an FHR of 94 gallons.
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significantly worse in terms of its energy
efficiency rating than if the rating were
determined based on testing without
storage tank overheating. In other
words, the rated efficiency at the rated
delivery capacity would not be
representative of an average use cycle or
period of use when operated in a highcapacity mode. 87 FR 42270, 42279
(July 14, 2022).
In the July 2022 SNOPR, DOE
surmised that consumers who purchase
a water heater that provides overheating
capability would do so with the intent
to use such capability; as such, these
consumers would be expected to use the
over-heated mode some portion of the
time, ranging from occasional use (e.g.,
switching between the normal mode
and the overheated mode depending on
the hot water capacity needed at any
particular time) to regular use.
Accordingly, for such products, DOE
expects that a representative average use
cycle would include some portion of
time in overheated mode. For this
reason, DOE tentatively determined that
testing storage-type water heaters that
offer user-selectable overheated modes
in the overheated mode would provide
a more representative result than testing
in the default mode. Therefore, DOE
proposed to amend section 5.1 of
appendix E to require that for water
heaters that offer a user-selected
operational mode(s) in which the
storage tank is maintained at a
temperature higher than the delivery
temperature, the operational mode shall
be that which results in the highest
mean tank temperature while
maintaining an outlet temperature of
125 °F ±5 °F. Because this amendment
would change the measured energy
efficiency, DOE proposed that
compliance with this requirement
would not be necessary until the
compliance date for amended energy
conservation standards. 87 FR 42270,
42279 (July 14, 2022).
As explained in the July 2022 SNOPR,
demand-response water heaters with the
capability to undergo utility-initiated
overheating would not be expected to
increase the capacity of the water heater
over a typical average use cycle in the
same way that a water heater with userinitiated overheating would, so DOE
had tentatively concluded that testing
demand-response water heaters in the
default/normal would be the most
representative method for those
products. Therefore, DOE proposed to
define ‘‘demand-response water heater’’
(see section III.A.1 of this document)
and exclude such products from the
requirement to test in the operational
mode that results in the highest mean
tank temperature while maintaining an
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outlet temperature of 125 °F ±5 °F, even
if they are capable of overheating the
stored water. 87 FR 42270, 42280 (July
14, 2022).
In response to the July 2022 SNOPR,
BWC stated that the phrase ‘‘storage
tank overheating’’ may be confusing to
consumers and suggested that DOE find
an alternate phrase to describe this
concept (i.e., ‘‘water heaters with high
heat modes’’). (BWC, No. 48 at p. 3)
GEA also disagreed with DOE’s use of
the term ‘‘over-heating’’ to refer to water
heaters that can deliver water at lower
temperature than that at which it is
stored, suggesting ‘‘delivery-control’’ as
an alternative, given that these products
heat in the manner intended. (GEA, No.
53 at p. 2) In response to these
comments and acknowledging the
sensitivity around the potentially
negative connotation of the term
‘‘overheating,’’ as noted earlier in this
document, DOE’s use of the term
‘‘overheating’’ does not denote
performance outside of the normal
operating range of the water heater, but
rather refers to raising the tank
temperature above the outlet water
setpoint. To avoid any potential
confusion, DOE will hereinafter refer to
water heaters with overheating
capability as water heaters with ‘‘high
heat modes.’’
The following subsections summarize
the remaining comments received in
response to the provisions proposed in
the July 2022 SNOPR for water heaters
with high heat modes and include
DOE’s additional assessments of the
impact on UEF ratings,
representativeness of the test method,
and implications for compliance with
standards associated with high
temperature testing.69 As discussed in
the following subsections, DOE has
concluded that including test conduct
provisions for determining the ratings of
water heaters tested using the high
temperature testing method would be
justified. Therefore, in this final rule,
DOE is establishing the methodology for
determining ratings for electric
resistance storage water heater using
high temperature testing in appendix E,
but DOE is allowing voluntary
representations at this point.
Specifically, manufacturers may opt to
use the high temperature test method in
addition to the regular temperature
69 DOE is establishing a method for testing water
heaters at an elevated tank temperature, including
water heaters without ‘‘high heat modes.’’
Therefore, DOE refers to water heaters with a builtin mixing valve and operational mode for
overheating the water in the tank as water heaters
with ‘‘high heat modes’’ but refers to the testing of
water heaters at elevated storage water temperatures
as ‘‘high temperature testing.’’
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setting test method if they desire to
make voluntary representations of the
efficiency when tested in high
temperature mode. DOE will consider
establishing requirements for which
electric resistance storage water heaters
must be tested and represented
according to the method for high
temperature testing in its ongoing
energy conservation standards
rulemaking for consumer water heaters.
Until such time, the regular test method
is mandatory for compliance with the
current Federal energy conservation
standards.
a. Impact on UEF Ratings
In response to the July 2022 SNOPR,
ASAP, ACEEE, and NRDC expressed
support for DOE’s proposal for
addressing storage-type water heaters
that heat the stored water beyond the
delivery temperature. (ASAP, ACEEE,
and NRDC, No. 54 at p. 2)
NEEA supported DOE’s proposal to
test water heaters in a user-selectable
‘‘overheat’’ mode when such a mode is
available, as well as DOE’s proposed
methodology for identifying ‘‘overheat’’
modes. NEEA also indicated that it had
performed testing on two 120-volt heat
pump water heater models which had
these modes available, and its test
results showed a significant reduction
in efficiency when the water heater was
set to store water at an elevated
temperature of 140 °F.70 Thus, NEEA
stated that requiring testing in the
‘‘overheat’’ mode would help realize the
energy and cost savings intended with
efficiency standards. (NEEA, No. 56 at
p. 2)
BWC disagreed that water heaters
with high heat modes should have
separate testing requirements and
expressed concern that tests to examine
the potential effects of heating stored
water above the delivery temperature
setpoint were conducted on a single 50gallon electric resistance storage water
heater. BWC urged DOE to conduct
further testing before finalizing this
proposal. (BWC, No. 48 at p. 3) In
response, DOE notes that the UEF
ratings of products which store water at
higher temperatures will be lower due
to the higher standby losses incurred as
a result of this high temperature storage.
DOE did, however, conduct additional
testing (see section III.F.2 of this
document) to determine that the method
of determining effective storage volume
from the high temperature testing will
only affect products which significantly
70 An August 30, 2022 report by NEEA containing
test data for these water heaters can be found online
at: neea.org/resources/plug-in-heat-pump-waterheaters-an-early-look-to-120-volt-products (Last
accessed on Nov. 22, 2022).
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increase capacity by increasing storage
temperature.
Additionally, DOE reviewed the heat
pump water heater test data referenced
in NEEA’s comment. NEEA tested two
50-gallon 120-volt heat pump water
heaters at two storage setpoint
temperatures (i.e., 125 °F and 140 °F),
with mixing valves installed to temper
the delivery to 120 °F. NEEA’s report
concludes that the recovery efficiency
can decrease by a factor of 3 to 8 percent
when the setpoint temperature is
increased from 125 °F to 140 °F. The
higher setpoint temperature resulted in
an increase in FHR of approximately 13
gallons. NEEA’s report also states that at
67.5 °F ambient air, an increase in the
setpoint temperature could increase
standby losses by 25 percent, although
NEEA stated that standby losses
contribute less to the overall energy
consumption of a heat pump water
heater compared to recovery periods.
DOE notes that NEEA did not conduct
standby loss testing or present the UEF
results of these water heaters in each
mode. DOE expects that the standby loss
from having a higher setpoint
temperature would have a more
significant impact on electric resistance
water heaters because the recovery
efficiency of electric resistance heating
is not affected by the water
temperature.71 However, in conjunction
with DOE’s own test data (which was
obtained through full 24-hour simulated
use test measurements of an electric
resistance storage water heater), DOE
has determined that high temperature
testing would result in significantly
lower UEF results compared to setting
the tank temperature close to the
delivery setpoint of 125 °F.
Given the significant difference in
UEF performance that have been
observed based on the temperature of
the water stored in the tank, DOE has
concluded it is appropriate to provide a
method to conduct high temperature
testing. Section III.E.1.d of this
document describes how DOE is
establishing the requirements for high
temperature testing. Due to the expected
impacts of high temperature testing on
UEF, DOE will not require compliance
with this test method until compliance
with amended energy conservation
standards accounting for such water
heaters is also required.
71 Section 6.3.2 of the currently applicable
appendix E test procedure (which will be re-located
to section 6.3.3 upon the effective date of this final
rule) states that the recovery efficiency for electric
water heaters with immersed heating elements, not
including heat pump water heaters with immersed
heating elements, is assumed to be 98 percent.
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b. Demand-Response Water Heaters
As discussed previously, in the July
2022 SNOPR, DOE proposed to define
‘‘demand-response water heater’’ and
exclude such products from the
proposed requirement to test in the
operational mode that results in the
highest mean tank temperature while
maintaining an outlet temperature of
125 °F ±5 °F, even if they are capable of
heating the stored water above the
delivery temperature. 87 FR 42270,
42280 (July 14, 2022).
In response to the July 2022 SNOPR,
NYSERDA indicated that water heaters
with demand-response functionality
should be excluded from testing at the
highest tank temperature available.
(NYSERDA, No. 50 at p. 3) A.O. Smith
agreed with DOE’s assessment that
demand-response water heaters need
the operational capability to ‘‘over-heat’’
the stored water in the tank above the
intended outlet water temperature in
response to a signal or command from
a utility or third-party aggregator. The
commenter stated that these load-up
events are typically short in duration
and do not keep the stored water in an
over-heated state continuously or
permanently. However, A.O. Smith
raised concerns about the impact of this
proposed amendment on the availability
of the high heat mode feature on nondemand-response products. A.O. Smith
urged DOE to continue to allow nondemand-response heat pump water
heaters with selectable high heat modes
to retain this functionality for customer
utility. (A.O. Smith, No. 51 at pp. 5–6)
In contrast, the CA IOUs suggested
that demand-response capable water
heaters should be subject to the same
test procedure as other water heaters
capable of operating in high heat modes.
(CA IOUs, No. 52 at p. 6)
As noted in section III.A.1 of this
document, DOE is not establishing a
definition for ‘‘demand-response water
heater’’ in this final rule in order to
prevent potential industry confusion
from arising due to any differences in
the features requirements specified in
such definition. However, DOE has
found it appropriate to still consider
factors which would help to determine
whether it is most representative to
require demand-response water heaters
to test at the highest tank temperature
setting.
As described in the July 2022 SNOPR
and discussed in section III.A.1 of this
document, high-temperature water
storage occurring in demand-response
water heaters and initiated by the
electric utility serves an important
purpose for energy storage and grid
flexibility. 87 FR 44270, 42279–42280
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(July 14, 2022). Additionally, DOE noted
that demand-response water heaters do
not perform this action to increase the
overall daily capacity of the water
heater. Instead, the capacity is only
temporarily boosted to counteract the
deactivation of the heating elements for
extended periods of time when demand
curtailment is occurring. As such,
demand-response water heaters with the
capability to undergo only utilityinitiated high heat modes would not be
expected to increase the capacity of the
water heater over a typical average use
cycle in the same way that a water
heater with the ability to have the user
increase the storage tank temperature
would. Id.
To reiterate, EPCA requires that any
test procedures prescribed or amended
shall be reasonably designed to product
test results which measure energy
efficiency, energy use, or estimated
annual operating cost of a covered
product or equipment during a
representative average use cycle or
period of use and not be unduly
burdensome to conduct. (42 U.S.C.
6293(b)(3); 42 U.S.C. 6314(a)(2)). Thus,
DOE must determine whether testing at
the highest tank temperature setting
during the delivery capacity test and the
24-hour simulated-use test is
representative of an average use cycle
for a demand-response water heater.
Based on information collected during
this rulemaking, including the comment
from NYSERDA, demand-response
water heaters do not typically remain in
a high-temperature storage state for the
entirety of a 24-hour average use cycle.
The additional energy used and stored
when this type of water heater increases
the tank temperature is offset by
significant periods of low energy usage
such that, over a 24-hour average use
cycle, the total energy stored and
consumed by the water heater is similar
to that for a product which maintains a
normal storage tank temperature
throughout the day.
In response to A.O. Smith’s concern
about non-demand-response water
heaters, as discussed in further detail in
sections III.E.1.c and III.E.1.d of this
document, DOE notes that the
provisions finalized in this rulemaking
do not require high temperature testing
for any water heaters in particular at
this time and, therefore, would not
preclude the possibility of non-demandresponse heat pump water heaters
having user-selectable high heat modes.
DOE will consider these concerns
further at such time as it proposes to
require high temperature testing for
certain types of water heaters in a future
rulemaking.
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c. Representativeness of Field Use
AHRI indicated that additional
operational modes to heat water above
125 °F are not meant to be the primary
mode of operation and should not be
used continuously. AHRI stated that the
proposal in the July 2022 SNOPR to test
water heaters with these modes at the
settings providing the highest internal
tank temperature does not reflect the
purpose of these modes, and that
proposal would require more test data
than provided in the NOPR to
understand its consequences. For these
reasons, AHRI requested that DOE
retract this proposal from the current
rulemaking and address it at a later
time. (AHRI, No. 55 at p. 6) Similarly,
Rheem requested that DOE not consider
water heaters with a temporary, nondefault high heat mode as being water
heaters with high heat modes and that
DOE not include any changes related to
high heat modes in the final rule.
(Rheem, No. 47 at p. 6)
GEA argued that the essential
function of ‘‘delivery-control’’ water
heaters is no different than a consumer
who sets their standard storage water
heater to a higher temperature and
regulates water temperature at the tap
by mixing in cold water. GEA added
that ‘‘delivery-control’’ water heaters
provide practical energy savings
benefits not captured by the consumer
water heater test procedure, and that
these energy savings benefits mitigate
against requiring testing at the
maximum tank storage temperature.
Specifically, GEA described a use case
where a consumer may use a ‘‘deliverycontrol’’ water heater in a high heat
mode on occasion when more guests are
in the home, which they suggested
would, on balance, use less energy as
compared to full time use of a water
heater with an oversized storage
capacity. (GEA, No. 53 at p. 3)
GEA suggested that many consumers
already set their storage water heater to
temperatures above 140 °F and that
‘‘delivery-control’’ water heaters simply
allow consumers to do so in a safer way
by premixing to a lower temperature,
adding that such water heaters should
not be penalized through efficiency
ratings for providing a safety feature to
prevent scalding. (GEA, No. 53 at p. 3)
GEA stated that DOE has provided no
evidence that setting ‘‘delivery-control’’
water heaters at their maximum storage
temperature is a ‘‘representative average
use cycle or period of use’’ as required
by EPCA at 42 U.S.C. 6293(b)(3). GEA
also noted that many other products
regulated under EPCA have modes that
allow for increased or decreased energy
consumption relative to their default
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setting but that these modes are not
included in their respective DOE test
procedures because they have not been
deemed representative of an average use
cycle. (GEA, No. 53 at p. 4)
NYSERDA recommended that all
water heaters with the option to elevate
the tank temperature, except those with
demand-response functionality, should
be tested at the highest tank temperature
available, as thermostatic mixing valves
are regularly installed in the field.
(NYSERDA, No. 50 at p. 3) The CA IOUs
also commented that external mixing
valves are readily available to
consumers, and in at least one State
(Vermont), they are required for all
residential water heater installations.
Therefore, the CA IOUs urged DOE to
consider changes to its regulations that
would further incentivize installers and
consumers to minimize installation
costs at the expense of energy efficiency.
(CA IOUs, No. 52 at p. 5) GEA stated
that thermostatic mixing valves can be
integrated into a product at the factory
or added as an accessory at a
consumer’s home and suggested that if
manufacturers are required to make
‘‘inaccurate’’ representations of energy
consumption for mixing valves
integrated at factories, more mixing
valves will be sold as accessories,
because consumer demand for
flexibility and safety will not change.
(GEA, No. 53 at p. 4)
As previously discussed in the July
2022 SNOPR and in response to the
comments of AHRI and Rheem, DOE
expects that consumers who purchase a
water heater with high heat modes
intend to use it in order to meet hot
water demands; therefore, testing these
water heaters using only the default
operational mode would not be
representative of the product’s energy
consumption over an average use cycle.
87 FR 42270, 42279 (July 14, 2022).
From its review of product literature,
DOE has found that manufacturers of
water heaters with high heat modes
market these products as smaller storage
water heaters which provide the
delivery capacities of larger storage
water heaters, and consumers may opt
to install a smaller water heater with
high heat mode in lieu of a larger water
heater as a result (e.g., if a larger water
heater does not fit in the installation
space). As such, in order to yield
efficiency results that would be most
representative of the product’s
enhanced delivery capabilities, DOE has
concluded that it would be necessary to
include a high temperature testing
method.
In light of these comments, DOE has
determined that the ability to operate
with an elevated tank temperature is not
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limited to products with built-in mixing
valves and user-selectable capacity
boosting settings. DOE agrees with
commenters that a product with a fieldinstalled mixing valve and the storage
tank manually set to a higher
temperature could operate in much the
same way, and that this practice may be
prevalent given how readily available
separate mixing valves are to
consumers. As a result of these
considerations, DOE concludes that it is
possible such testing could be
appropriate for models capable of
heating and storing water above the
delivery temperature specified in the
test method while still delivering water
at the setpoint temperature of 125 ± 5 °F.
Thus, DOE is not limiting the high
temperature testing method only to
products with a specific capacity
boosting mode. In other words,
manufacturers may optionally apply the
high temperature test method to electric
resistance storage water heaters with the
capability to heat and store water above
the delivery setpoint temperature of 125
± 5 °F, including products that would
require a field-installed mixing valve to
do so.
The provisions for high temperature
testing adopted by this final rule
complement the existing operational
mode selection requirements, which,
generally, would require water heaters
to be set to a ‘‘normal’’ storage tank
temperature close to the delivery
setpoint of 125 °F (see section 5.2.1 of
the currently applicable appendix E test
procedure). Specifically, the high
temperature testing provisions require
setting the water heater to the highest
storage tank temperature and installing
a separate mixing valve to temper the
delivery water to the outlet water
requirements for products that do not
already have a mixing valve installed. If
the product is equipped with a built-in
mixing valve, then the water heater’s
storage tank temperature shall be set to
the highest temperature which allows
the built-in mixing valve to deliver
water in accordance with the outlet
water requirements.
d. Use of High Temperature Testing
In response to the July 2022 SNOPR,
NEEA agreed with DOE’s proposal to
implement this testing requirement only
upon adoption of new standards.
(NEEA, No. 56 at p. 2) A.O. Smith
supported the Department’s position
that the effective date of the proposed
changes to the test procedure covering
user-selectable over-heat modes for
non-demand-response water heaters
should coincide with the compliance
date of any amendments to the energy
conservation standards for consumer
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water heaters. (A.O. Smith, No. 51 at p.
6)
Rheem stated that DOE’s proposal to
delay testing until amended standards
are required may not align with EPCA
at 42 U.S.C 6293(c)(2) 72 and requested
clarification on DOE’s interpretation of
this statutory provision. (Rheem, No. 47
at p. 5) Rheem also requested DOE’s
interpretation of the 42 U.S.C. 6293(e)(2)
requirement to ‘‘amend the applicable
energy conservation standard during the
rulemaking carried out with respect to
such test procedure’’ with respect to
water heaters with high heat modes
because the amended test procedure
will alter their measured efficiency.
(Rheem, No. 47 at p. 5)
In response to Rheem’s questions
regarding the relevant statutory
provisions at 42 U.S.C. 6293(c)(2) and
(e)(2), DOE has concluded that the
Department’s approach comports with
both of these EPCA provisions. To
recap, as discussed in section III.I of this
document, DOE is not requiring
compliance with the high temperature
testing provisions until compliance with
amended energy conservation standards
that address water heaters with such
capabilities, if finalized, because DOE
has determined that this change to the
test procedure will impact the measured
efficiency of such water heaters. Under
42 U.S.C. 6293(c)(2), effective 180 days
after an amended or new test procedure
is prescribed or established for a
covered product, no regulated party
(i.e., manufacturer, distributor, retailer,
or private labeler) may make any
representations about the energy use or
efficiency of such product unless it has
been tested according to the new or
amended test procedure and such
representations fairly disclose the
results of such testing. In the present
case, DOE is making clear that its test
procedure provisions related to high
temperature testing are not required to
be used until the compliance date of any
amended standards that address such
water heaters.
Under 42 U.S.C. 6293(e)(1), DOE must
determine whether any test procedure
amendments would alter the measured
energy efficiency, energy use, or
72 Under 42 U.S.C. 6293(c)(2), the statute provides
that effective 180 days after an amended or new test
procedure applicable to a covered product is
prescribed or established under paragraph (b) of
this section, no manufacturer, distributor, retailer,
or private labeler may make any representation—
(A) in writing (including a representation on a
label); or (B) in any broadcast advertisement, with
respect to energy use or efficiency or, in the case
of showerheads, faucets, water closets, and urinals,
water use of such product or cost of energy
consumed by such product, unless such product
has been tested in accordance with such amended
or new test procedure and such representation
fairly discloses the results of such testing.
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measured water use of any covered
products as determined under the
existing test procedure. As explained
elsewhere, DOE has determined that the
provisions for high temperature testing
would alter measured efficiency, so this
statutory provision is likewise satisfied.
Finally, under 42 U.S.C. 6293(e)(2), if
DOE determines that its amended test
procedure will alter the measured
energy efficiency or energy use of a
covered product, the Department shall
amend the applicable energy
conservation standard during the
rulemaking carried out with respect to
such test procedure. This provision
applies to the currently applicable
energy conservation standard. As noted
previously, the high temperature testing
provisions that would alter the
measured energy efficiency of certain
water heaters are not required for
determining compliance with the
currently applicable standard. These
provisions would only be required on
the compliance date of any amended
standards that address such water
heaters. As such, there is no need to
amend the current standards under 42
U.S.C. 6293(e)(2).
DOE has determined that the high
temperature test method should apply
to electric resistance storage water
heaters for the reasons discussed in
section III.E.1 of this document.
Specifically, based on information from
stakeholders regarding the operation of
demand-response water heaters (see
section III.E.1.b of this document) and
the Department’s own testing and
calculations (see section III.F.2.a of this
document), DOE has determined that
the high temperature test method would
apply to electric resistance storage water
heaters that are capable of raising their
internal tank temperature significantly
above their delivery temperature,
without utility initiation, to boost hot
water delivery capacity in order to meet
daily household needs. Products which
raise the internal tank temperature only
as part of demand-response operation
should not use this method.
In this rulemaking, commenters have
urged DOE to provide better clarity and
specificity regarding which water
heaters may be ‘‘exempt’’ from high
temperature testing (for example, see
NYSERDA’s comments discussed in
section III.A.1 of this document). In the
concurrent the energy conservation
standards rulemaking, DOE may
consider and propose additional criteria
to further specify the subset of water
heaters which would have to comply
with potential amended standards using
the high temperature test method. This
is because there could be specific cases
when a water heater would reach a
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higher storage tank temperature in a
way that does not necessarily increase
the delivery capacity over the course of
an average use cycle. For example, a
user may choose to use an elevated
setpoint for storage temperature, but
with a delivery temperature equal to
this setpoint. In such a case where a
higher delivery temperature is actually
desired, because no cold water mixing
is occurring at the outlet, there is no
increase in the volume of hot water that
can be provided to the home. Therefore,
in its accompanying energy
conservation standards rulemaking for
consumer water heaters, DOE will
consider specifying what usercontrollable tank temperature settings
might actually constitute ‘‘delivery
capacity boosting.’’ Additionally, DOE
will also consider the length of time
these settings may be in use to
determine which types of temperature
settings would result in capacity
boosting over an average daily use cycle.
Once again, because high temperature
testing may cause ratings for certain
electric resistance storage water heaters
to decrease, DOE is not requiring the use
of these test provisions until the
compliance date of any new energy
conservation standards addressing such
water heaters (i.e., as part of the separate
rulemakings for consumer water
heaters). After the effective date of this
final rule and before the compliance
date of an amended standards final rule,
manufacturers of certain electric
resistance storage water heaters will be
allowed to use the high temperature test
method voluntarily to make additional
representations of performance in hightemperature mode.
2. Very Small Draw Pattern Flow Rate
Section 5.4.1 of appendix E states that
if the Max GPM is less than 1.7 gpm (6.4
L/min), then the very small draw
pattern must be used during the 24-hour
simulated-use test. Section 5.5 of
appendix E states that, for the very
small draw pattern, if the water heater
has a Max GPM rating less than 1 gpm
(3.8 L/min), then all draws shall be
implemented at a flow rate equal to the
rated Max GPM.
As discussed in the January 2022
NOPR, DOE has identified flowactivated water heaters that are designed
to deliver water at the set point
temperature of 125 °F ±5 °F (51.7 °C
±2.8 °C) that is required by section 2.5
of appendix E at a flow rate well below
1 gpm (3.8 L/min). For these products,
the second draw of the very small draw
pattern requires 1 gallon to be removed
at the rated Max GPM, and the pattern
requires the third draw to start five
minutes after the initiation of the
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second draw. However, any rated Max
GPM less than or equal to 0.2 gpm (0.76
L/min) will result in the second draw
lasting more than five minutes and past
the start time of the third draw. To
clarify the appropriate method of testing
these products, DOE proposed to amend
the very small draw pattern description
to state that when a draw extends
beyond the start time of a subsequent
draw, that the subsequent draw will
start after the required volume of the
previous draw has been delivered. 87
FR 1554, 1582 (Jan. 11, 2022).
DOE did not receive any comments in
response to this proposal, so, therefore,
in this final rule, DOE is adopting the
amendment to appendix E as proposed
in the January 2022 NOPR for the
reasons previously stated.
3. Low-Temperature Water Heaters
Low-temperature water heaters
(discussed further in section III.A.4.b of
this document) are flow-activated
products that do not deliver
temperatures within the required set
point temperature range of 125 °F ±5 °F
when tested according to the supply
water temperature and flow rate
requirements of appendix E. These
products are typically suited for pointof-use (POU) applications where the
outlet water is minimally tempered
prior to delivery through the faucet
(typically marketed as ‘‘handwashing’’
or ‘‘POU water heaters’’). However,
because these products cannot meet the
outlet temperature requirements in
appendix E, DOE is establishing new
provisions to address these products.
One primary concern identified in
this rulemaking is that these units
typically have low heating rates, which
currently requires the testing agency to
reduce the flow rate in order to be able
to achieve the outlet temperature within
the set point temperature range.
However, these units have a minimum
activation flow rate below which the
unit shuts off. To the extent that a unit
would stop heating water when the flow
rate is too low, there may be no flow
rate at which the unit would operate
and deliver water at the outlet
temperature required under section 2.5
of appendix E. In response to the April
2020 RFI, commenters generally
indicated that DOE should adopt
provisions to use a lower setpoint
temperature for low-temperature water
heaters. 87 FR 1554, 1582 (Jan. 11,
2022).
For the reasons explained in further
detail in the January 2022 NOPR, DOE
proposed that low-temperature water
heaters be tested at the maximum
delivery temperature when using the
flow rate requirements already
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established in appendix E. Specifically,
lowering the flow rate in order to
establish a delivery temperature of
125 °F may not be feasible for these
products because the flow rate may be
so low that the water heater does not
activate. DOE tentatively determined
that lowering the set point temperature
for low-temperature water heaters to
their maximum possible delivery
temperature would permit these water
heaters to be tested appropriately and in
a manner that would produce
representative test results. 87 FR 1554,
1582–1583 (Jan. 11, 2022).
In commenting on this issue, BWC
requested that DOE further assess
differences in testing and ratings
between electric instantaneous water
heaters and low-temperature water
heaters. (BWC, No. 33 at p. 8)
In response, DOE will continue to
assess the impact of the test procedure
provision in section 5.2.2 of appendix E
on ratings for low-temperature water
heaters as more of these products enter
the market and are certified, but at this
time, DOE is adopting these provisions
in order to set forth a repeatable,
representative approach to testing such
products. Currently, there is no
appendix E test method to test lowtemperature water heaters, and,
therefore, ratings for low-temperature
water heaters are not possible until the
effective date of this final rule. DOE is
distinguishing low-temperature water
heaters from other electric
instantaneous water heaters mainly on
the inability to reach the standardized
outlet water temperatures under the
appendix E test procedure. DOE will
consider potential impacts on UEF
ratings in its concurrent energy
conservation standards rulemaking (see
Docket No. EERE–2017–BT–STD–0019).
4. Delivery Temperature for FlowActivated Water Heaters
In providing comments in response to
the January 2022 NOPR, AET
introduced a new topic for DOE to
consider when amending the test
procedure for consumer water heaters
and residential-duty commercial water
heaters. AET indicated that the test
procedure needs to further clarify the
process for setting the delivery
temperature for flow-activated water
heaters. The commenter argued that
such clarification is necessary because
the DOE test procedure simply says to
initiate normal operation of the water
heater at the design power rating. AET
stated that, when operating flowactivated water heaters at their
maximum heating rate, outlet
temperature can be controlled two
different ways: (1) adjust some
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thermostat, and/or (2) adjust flow rate;
since the instructions do not specify a
flow rate at which to set the thermostat,
it is theoretically possible to set the
thermostat to a very high temperature,
and then adjust the flow rate so that the
unit only delivers the desired 125 °F
outlet temperature. AET claimed that
this would allow the water heater to
deliver much hotter temperatures when
the flow rate is less than the flow rate
needed to deliver 125 °F when operating
at maximum heating rate. AET
recommended to amend the test
procedure so as to provide instructions
that the flow rate for draws should be
90 percent of the theoretically
calculated maximum flow rate that
could be achieved when operating at a
full heating rate and delivering the
required 125 °F outlet temperature in
order to ensure that this temperature is
consistent. (AET, No. 29 at p. 11)
On this issue, DOE notes that section
5.2.2.1 of appendix E, ‘‘Flow-Activated
Water Heaters, including certain
instantaneous water heaters and certain
storage-type water heaters,’’ instructs
the test agency to first initiate normal
operation of the water heater at the full
input rating for electric water heaters
and at the maximum firing rate
specified by the manufacturer for gas or
oil water heaters. Section 5.2.2.1 then
states that the test agency must monitor
the discharge water temperature and set
to a value of 125 °F ±5 °F (51.7 °C
±2.8 °C) in accordance with the
manufacturer’s instructions. If the water
heater is not capable of providing this
discharge temperature when the flow
rate is 1.7 gallons ±0.25 gallons per
minute (6.4 liters ±0.95 liters per
minute), then the flow rate is adjusted
as necessary to achieve the specified
discharge water temperature. Once the
proper temperature control setting is
achieved, the setting must remain fixed
for the duration of the maximum GPM
test and the simulated-use test.
In response to AET’s comment, DOE
notes that the current appendix E test
instructions specify that the flow rate
for setting the discharge water
temperature is 1.7 gallons ±0.25 gallons
per minute (6.4 liters ±0.95 liters per
minute). If a discharge temperature of
125 °F ±5 °F is not possible at that flow
rate, the test method allows for the flow
rate to be varied only to the extent
necessary to achieve a discharge
temperature of 125 °F ±5 °F. Therefore,
DOE has determined that the current
instruction is explicit enough for the
delivery temperature setting to be
conducted in a repeatable and
reproducible manner.
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5. Heat Pump Water Heaters
In this rulemaking, DOE has sought to
address multiple test procedure
provisions related to heat pump water
heaters. In section III.A.2 of this final
rule, DOE discusses the scope of
applicability of the appendix E test
procedure to heat pump water heaters
designed for residential applications.
Section III.C.7 of this document
describes the new optional test
conditions being allowed for heat pump
water heaters for voluntary
representations of EX based on NEEA’s
Advanced Water Heating Specification.
Additionally, DOE is amending ambient
air condition tolerances for heat pump
water heater testing because air-source
heat pumps exchange latent and
sensible heat 73 with the surrounding
air, and, thus, the water heater’s normal
operation will have a tangible impact on
air temperature and moisture content
(see section III.C.4 of this document).
Furthermore, there are other
requirements being established for the
test set-up and installation of splitsystem heat pump water heaters and
circulating heat pump water heaters (see
sections III.D.1 and III.D.4 of this
document).
In addition to these topics, DOE has
evaluated the draw patterns for
conducting the 24-hour simulated-use
test on heat pump water heaters with
back-up electric resistance heating
elements. In the present market,
consumer heat pump water heaters are
typically ‘‘integrated,’’ with the airsource heat pump and storage tank built
together into one assembly. This
‘‘typical’’ consumer heat pump water
heater uses electricity and has back-up
electric resistance elements within the
storage tank. Heating water with the
heat pump components is more efficient
than heating water with the back-up
resistance elements. Therefore, water
heaters with controls that prioritize heat
pump water heating over resistance
element water heating will operate more
efficiently than water heaters that do not
prioritize heat pump water heating or
that do not prioritize heat pump water
heating to the same extent.
In response to the April 2020 RFI, the
Joint Commenters suggested modifying
the test procedure to reflect the
effectiveness of controls in minimizing
use of the resistance element in heat
pump water heaters, stating this
modification would improve the
73 ‘‘Sensible heat’’ refers to heat that is exchanged
with surrounding air that is detectable by
measuring the change in temperature of the air, as
it does not change the moisture content of the air.
‘‘Latent heat’’ refers to heat that is exchanged when
moisture in the air is condensed into liquid water
(i.e., at the evaporator of a heat pump water heater).
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representativeness of the test procedure
and create new incentives for
manufacturers to develop products that
provide increased savings for
consumers. As noted in the January
2022 NOPR, no suggestion was provided
on how to better reflect the use of
controls to minimize element usage. 87
FR 1554, 1583 (Jan. 11, 2022).
In the January 2022 NOPR, DOE noted
that its test data indicate that most (or
possibly all) heat pump water heater
models available on the market
currently operate without activating the
electric elements during the 24-hour
simulated-use test under the current
appendix E test procedure. DOE argued
that although element usage during the
test could be forced through a more
aggressive draw pattern (i.e., longer or
more frequent draws designed to
deplete the water heater and require
more hot water than the heat pump
alone could keep up with), the draw
patterns are required to be
representative of actual use. Therefore,
designing the draw pattern with the goal
of forcing resistance element use would
not be representative of typical use. 87
FR 1554, 1583 (Jan. 11, 2022).
In commenting on this issue in
response to the January 2022 NOPR, the
ASAP, ACEEE and NCLC once again
encouraged DOE to evaluate whether
current draw patterns are representative
of real-world conditions for heat pump
water heaters. The ASAP, ACEEE and
NCLC noted that investigations
conducted by NEEA 74 indicate that
electric resistance elements are
activated more frequently in heat pump
water heaters than DOE observed in its
testing. Specifically, ASAP, ACEEE and
NCLC pointed to the finding in the
NEEA study that the average annual
proportion of total input energy that was
provided by resistance heat ranged from
4 to 45 percent, depending on the water
heater model and location of
installation. (ASAP, ACEEE, and NCLC,
No. 34 at p. 2) However, DOE did not
receive any additional comments in this
rulemaking providing any specific
approach to testing heat pump water
heaters with back-up electric resistance
elements in a more representative
manner.
In response, DOE notes that the 2015
study by NEEA relies on data collected
in a limited geographical area within the
U.S.—namely, the Pacific Northwest—
and the results may not be
representative of installations across the
74 ASAP, ACEEE and NCLC cited NEEA’s 2015
Heat Pump Water Heater Model Validation Study,
(Report #E15–306), found online at:
ecotopewebstorage.s3.amazonaws.com/2015_001_
1_HPWHModelVal.pdf (Last accessed on Sept. 13,
2022).
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U.S, which is the requisite benchmark
for a Federal test procedure. For
example, one condition for electric
resistance back-up is when the ambient
air temperature is below the lowtemperature cut-out of the compressor
(e.g., 45 °F), and this is more likely to
occur in northern climates than it is to
occur across the country as a whole.
Nevertheless, the study finding
demonstrated a substantial range of
electric resistance contribution, such
that it remains unclear whether an
amended draw pattern would be more
representative.
The CA IOUs did, however, suggest
that DOE should consider any
distinguishing characteristics of 120volt heat pump water heaters that might
require changes to the test procedure to
represent their real-world performance
accurately. (CA IOUs, No. 36 at p. 4) In
response to the CA IOUs, within the
context of back-up element usage, early
indications suggest that not all 120-volt
heat pump water heaters will employ
back-up electric resistance heating
elements due to limitations on a 120volt circuit, but this market is still
evolving. As of this final rule, there are
only a limited number of commerciallyavailable 120-volt heat pump water
heaters, so DOE has determined that it
is premature to establish specific testing
requirements for 120-volt heat pump
water heaters at this time. Without
adequate test data from these products,
there is uncertainty as to what, if any,
specific requirements for 120-volt heat
pump water heaters would be
appropriate.
Therefore, after considering these
comments and the lack of available data
on this topic, DOE has decided to
maintain the current language in section
5.1 of appendix E and is not adopting
draw patterns specific to any type of
heat pump water heater. Accordingly,
the draw patterns for electric water
heaters generally will continue to apply
to these products. DOE will continue to
collect information on this topic to
inform a future test procedure
rulemaking.
6. Draw Pattern for Commercial
Applications
In response to the April 2020 RFI and
as discussed in the January 2022 NOPR,
EEI suggested DOE consider a test
procedure for consumer water heaters
used in commercial applications that
includes a draw pattern more
demanding than the ‘‘high’’ draw
pattern, which is currently the draw
pattern with the largest amount of
delivered water in the appendix E test
procedure. 87 FR 1554, 1575–1576 (Jan.
11, 2022).
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In the January 2022 NOPR, DOE
stated that 42 U.S.C. 6293(b)(3), in
relevant part, requires that any test
procedures prescribed or amended shall
be reasonably designed to produce test
results which measure energy efficiency
of a covered product during a
representative average use cycle or
period of use. Consumer water heaters
are designed for use in residential
applications, and as such, a draw
pattern representative of a commercial
installation would not be representative
of the product’s average use cycle or
period of use. For these reasons, DOE
declined to propose a draw pattern with
a delivered volume greater than the high
draw pattern in appendix E. 87 FR 1554,
1576 (Jan. 11, 2022).
BWC agreed that there is no need for
a draw pattern above ‘‘high draw,’’ since
the high draw pattern adequately
addresses products that have high hot
water deliverability within the scope of
the test procedure. (BWC, No. 33 at p.
6)
As such, DOE is not adding another
draw pattern to the appendix E test
procedure in this final rule for the
reasons previously stated.
7. Method for Determining Internal
Tank Temperature for Certain Water
Heaters
Section 4.5 of appendix E provides
the procedure for measuring the internal
storage tank temperature for water
heaters with a rated storage volume at
or above 2 gallons. Section 4.5 of
appendix E specifies that the
thermocouples be inserted into the
storage tank of a water heater through
either the anodic device opening, the
temperature and pressure relief valve, or
the outlet water line. However, DOE has
identified consumer water heaters with
physical attributes that make measuring
internal storage tank temperature
difficult, such as water heaters that have
a built-in mixing valve and no anodic
device, or that have a large heat
exchanger that does not accommodate
insertion of a thermocouple tree. In this
rulemaking, DOE sought suggestions
from stakeholders on how the internal
storage tank temperature should be
measured for these types of designs.
After considering the comments
received, DOE is amending the
appendix E test procedure to specify a
method for determining the internal
mean tank temperature for such
products, as discussed in detail later in
this section.
In response to the April 2020 RFI and
as discussed in the January 2022 NOPR,
BWC recommended a ‘‘drain-down’’
approach to address water heaters that
cannot have their internal storage tank
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temperatures measured directly (a
position echoed by Rheem). More
specifically, BWC’s suggested approach
consisted of the following: (1) After the
FHR test, purging the water heater with
inlet water at 58 °F ± 2 °F to establish the
mean tank temperature at the beginning
of the 24-hour simulated-use test; (2)
allowing the water heater to heat up to
the original thermostat setting and
recording the energy used to do so; (3)
running the appropriate draw pattern,
then fully draining the water heater by
gravity, while measuring the mass and
temperature of the water; and (4)
calculating the energy change as: energy
change = mass × specific heat × the
difference between the average end
temperature and the beginning
temperature just after the 58 °F purge.
Rheem also supported a drain-down
method, whereby the entire volume
would be removed and the temperature
measured at the end of the 24-hour test.
87 FR 1554, 1586 (Jan. 11, 2022).
However, DOE’s primary concern
with the suggested drain-down
approach was that it cannot be
conducted at every stage during the 24hour simulated-use test when the mean
tank temperature measurement is
required. As discussed in the January
2022 NOPR, the procedures
recommended by BWC and Rheem
could provide an estimate of the mean
tank temperature at the start and end of
the 24-hour simulated-use test but
would not provide an estimate at the
end of the first recovery period, the start
and end of the standby period, or an
average over the standby period, all of
which are required for determining
UEF. Instead of BWC’s drain-down
approach, DOE initially proposed a
methodology with a modified approach,
wherein the mean tank temperature
would be estimated as the average of the
inlet water temperature and the outlet
water temperature each time a mean
tank temperature measurement was
required. This method assumes that the
stored water gradually (i.e., linearly)
increases in temperature either from the
bottom of the tank to the top, or the
further the water is into the heat
exchanger from the water inlet,
depending on the design of the water
heater being tested. As the exact internal
dimensions of the storage tank or heat
exchanger cannot be known for every
water heater, DOE reasoned that the
linear assumption is the most
representative of the water heater
market as a whole. 87 FR 1554, 1586–
1587 (Jan. 11, 2022).
In response to DOE’s proposal, AHRI,
A.O. Smith, and BWC indicated that the
linear temperature gradient assumption
inherent to the proposed methodology
in the January 2022 NOPR is incorrect,
based on the companies’ own test
results. (AHRI, No. 40 at p. 5; A.O.
Smith, No. 37 at pp. 5–6; BWC, No. 33
at p. 10) In contrast, Rheem supported
DOE’s proposed linear temperature
gradient assumption. (Rheem, No. 31 at
p. 4) None of the comments received in
response to the January 2022 NOPR
suggested an alternative approach, so in
the July 2022 SNOPR, DOE revised its
proposal to incorporate aspects of
BWC’s method but included additional
methods to estimate the intermediate
temperatures required for efficiency
calculations. 87 FR 42270, 42283–42284
(July 14, 2022).
In the July 2022 SNOPR, DOE
proposed the following methodology for
water heaters with rated storage
volumes greater than or equal to 2
gallons that are unable to have their
internal tank temperatures measured
using thermocouples:
(1) After the FHR test (for non-flowactivated products) or Max GPM test (for
flow-activated products), allow the
water heater to fully recover.
(2) When cut-out occurs, deactivate
the burner, compressor, and/or
electrical heating elements.
(3) Remove the hot water from the
tank by performing a continuous draw,
while measuring the outlet water
temperature at 3-second intervals, until
the outlet water temperature is within
2 °F of the inlet water temperature for
five consecutive readings. Perform the
draw at a flow rate of 3.0 gallons per
minute (±0.25 gallons per minute).
Compute the mean tank temperature,
Tst, as follows and assign this value as
T0, Tsu,0, and Tmax,1:
Where:
Tst = the estimated average internal storage
tank temperature.
Tp = the average of the inlet and the outlet
water temperatures at the end of the period
defined by tp.
vout,p = the average flow rate during the
period.
Vst = the rated storage volume of the water
heater.
tp = the duration of the period, determined
by the length of time taken for the outlet
water temperature to be within 2 °F of the
inlet water temperature for 15 consecutive
seconds. The duration of the period shall
include the 15-second stabilization period.
Tin,p = the average of the inlet water
temperatures during the period.
Tout,p = the average of the outlet water
temperatures during the period.
(5) The standby period will start at
five minutes after the end of the first
recovery period after the last draw of the
simulated-use test. The standby period
shall last eight hours, so testing will
extend beyond the 24-hour duration of
the simulated-use test. At the end of the
final standby measurement, remove
water from the tank once again as in
step #3, including computing the value
of mean tank temperature. This
calculated mean tank temperature is
then assigned as Tsu,f and T24.
(6) Determine Tt,stby,1 as the average
of Tsu,0 and Tsu,f.
The revised proposal relied on a
different assumption—supported by
DOE’s test data—that, for typical
storage-type water heaters, T0, Tsu,0, and
Tmax,1 are similar in that they represent
temperatures near the cut-out control
temperature. Furthermore, the mean
tank temperature at the end of the
standby period, Tsu,f, can also be
measured by removing water and
measuring its temperature at the end of
a sufficiently long standby period at the
end of the test, and this value could also
approximate T24. 87 FR 42270, 42284–
42285 (July 14, 2022).
In response to the July 2022 SNOPR,
AHRI stated that manufacturers would
need additional time to complete testing
to verify the proposed equations and
requested that DOE provide additional
data and evidence that the method is
appropriate before adopting it. Further,
AHRI asked that DOE specify the correct
procedure if the initial recovery period
extends beyond the start of the second
draw. (AHRI, No. 55 at p. 8) A.O. Smith
expressed support for the revised
proposal in the SNOPR, but the
commenter added that manufacturers
will need to work with the Department
as additional testing on the identified
products ensues, should this proposed
change become part of any final rule.
(4) Re-activate the burner,
compressor, and/or electrical elements
and perform the 24-hour simulated use
test as instructed in section 5.4 of
appendix E.
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Federal Register / Vol. 88, No. 118 / Wednesday, June 21, 2023 / Rules and Regulations
(A.O. Smith, No. 51 at p. 9) BWC stated
that the equation presented in the
SNOPR is an improvement over the
January 2022 NOPR proposal that will
more effectively measure internal tank
temperatures. However, BWC also
commented that it has insufficient data
to support or reject some elements of the
proposal, and the company provided as
an example the DOE’s assumption made
in the SNOPR proposal that Tmax and Tsu
are similar. BWC explained that it
would like to conduct additional testing
before commenting further. (BWC, No.
48 at p. 5)
Rheem noted that the procedure as
proposed in section 5.4.2.2 of the
proposed appendix E does not align
with steps 1 and 2 of the preamble.
Specifically, Rheem argued that the
preamble states that after the FHR or
Max GPM test, the unit should be
allowed to fully recover, and then, one
would deactivate the burner,
compressor, and/or elements, and
remove the hot water from the tank,
which would result in a comparatively
‘‘hot’’ water temperature that is
representative of a Tmax,1 or Tsu,0 value,
both of which are measured after a draw
and that is normally followed by a
recovery; however, section 5.4.2.2 of the
proposed appendix E states that a 1hour idle period is to be performed prior
to draining the tank, which would result
in a comparatively ‘‘low’’ water
temperature that is representative of T0,
a measurement taken after an idle
period where no energy was added to
the tank. Rheem requested DOE clarify
which method should be used. (Rheem,
No. 47 at p. 8) Rheem also requested
DOE clarify when a soak-in period is
required when testing a water heater
that cannot have the internal storage
tank temperature directly measured, and
specifically, the commenter asked
whether a soak-in period is required
between draining the tank after FHR
testing and starting the 24-hour
simulated use portion of the test.
(Rheem, No. 47 at p. 8)
Rheem stated that the proposed
procedure drains water from the unit at
a flow rate of 3 gpm until the inlet and
outlet temperatures match, which
means all energy in the water and tank/
heat exchanger has been removed from
the unit under test. Rheem requested
that DOE clarify that this is the intent
of the procedure and suggested that as
an alternative, since the storage volume
is known, the test could simply remove
the stored water and estimate the
internal tank temperature using the
proposed equation. (Rheem, No. 47 at p.
8) Rheem also recommended that the
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flow rate used for draining the tank be
the flow rate of draw 1 of the 24-hour
simulated-use test and that the
temperatures be measured throughout
the draw, not just after the first 15
seconds, stating that the flow rate of 3
gpm may be too fast for some water
heaters or would not account for the
true energy content of the internal
water. (Rheem, No. 47 at p. 8) Lastly,
Rheem requested that DOE provide the
derivation of the Tst equation, stating
that the derivation and assumptions are
not immediately apparent. (Rheem, No.
47 at, p. 9)
In response, DOE provides the
following clarifications. With respect to
AHRI’s request for clarification of the
test procedure in terms of whether the
initial recovery period extends beyond
the start of the second draw, DOE notes
that the tank would only be drained of
hot water twice regardless of when the
initial recovery period ends—once after
recovery after the FHR or max GPM test,
and once at the end of the standby
period at the end of the test. The mean
tank temperature determined during the
first draining would be used to
approximate Tmax,1 regardless of when
that actually occurs during the test, as
DOE expects that Tmax,1, which occurs
after the first recovery period ends,
would not vary significantly depending
on whether it occurs after the second
draw. Regarding Rheem’s request for a
clarification of whether a 1-hour idle
period is required before the first time
drawing off all of the hot water in the
tank, DOE clarifies that the 1-hour idle
period is required, as was presented in
the regulatory text in the SNOPR. As
shown in Table III.3 which follows, T0
measurements taken after the 1-hour
idle period are comparable to Tmax,1 and
Tsu,f measurements. In addition, for
tanks for which the internal tank
temperature cannot be directly
measured, the same soak-in provisions
apply as those that apply generally as
described in sections 5.2.4 and 5.4.2 of
appendix E.
Regarding Rheem’s suggestion to
remove volume of stored water in the
tank and use the average temperature of
that water to represent the measured
mean tank temperature, DOE notes that
when drawing off hot water through the
hot water outlet, cold water is
introduced into the tank which could
mix with the stored water. Removing
only the stored volume in the tank
could result in an artificially low mean
tank temperature due to the cold inlet
water mixing with the stored water,
whereas the proposed approach
accounts for all of the thermal energy
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40455
contained in the tank to estimate the
temperature of the stored water prior to
removing the hot water from the tank.
A valid estimate of the tank temperature
could be obtained by shutting off the
supply (inlet) water line and draining
the tank by gravity using the drain at the
bottom. However, such an approach
would likely require additional
equipment for the test set-up, such as an
additional temperature sensor, a
flowmeter to measure the water leaving
through the drain, and a flow control
valve to manage the water exiting the
drain, equipment not currently included
in the typical test set-up. In addition,
DOE has found that for some water
heaters, even after draining by gravity,
a small volume of water remains in the
bottom of the tank, which would be
difficult to account for under such an
approach. After considering these
comments, DOE has concluded that the
methodology proposed in the SNOPR
would not require changes to the test
set-up and, therefore, would be less
burdensome.
DOE agrees with Rheem that a flow
rate of 3.0 gpm may not be appropriate
for all water heaters, and in particular
it may be too high for temperature
sampling rates to accurately estimate the
mean tank temperature of smaller water
heaters. Thus, DOE is adopting Rheem’s
suggestion to withdraw water at a flow
rate equal to the flow rate of the first
draw in the applicable draw pattern.
DOE also agrees with Rheem that
starting the measurements immediately,
rather than after 15 seconds, would
provide a more accurate representation
of tank temperature, and, therefore, the
Department is adopting that
recommendation as well.
In response to these comments, DOE
re-evaluated its own test data in order
to further validate the method for
determining internal tank temperature
outlined above. Underpinning this
method is an assumption that during a
simulated use test, the mean tank
temperatures that occur after the tank
has been in standby for some time, Tsu,f
and T24, are typically very similar to
each other, and that the tank
temperatures measured soon after a
recovery and subsequent ‘‘cut-out’’,
Tsu,0, T0, and Tmax,1, are also typically
very similar to each other. This is
because water heaters with thermostats
have a control band near the setpoint
which directs the cut-in and cut-out to
occur once the setpoint is reached.
Table III.2 and Table III.3 below show
the mean tank temperatures for a sample
of 29 consumer water heaters.
E:\FR\FM\21JNR2.SGM
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Federal Register / Vol. 88, No. 118 / Wednesday, June 21, 2023 / Rules and Regulations
TABLE III.2—Tsu,f AND T24 VALUES FOR WATER HEATERS TESTED BY DOE
Test No.
Product type *
1 ....................................................
2 ....................................................
3 ....................................................
4 ....................................................
5 ....................................................
6 ....................................................
7 ....................................................
8 ....................................................
9 ....................................................
10 ..................................................
11 ..................................................
12 ..................................................
13 ..................................................
14 ..................................................
15 ..................................................
16 ..................................................
17 ..................................................
18 ..................................................
19 ..................................................
20 ..................................................
21 ..................................................
22 ..................................................
23 ..................................................
24 ..................................................
25 ..................................................
26 ..................................................
27 ..................................................
28 ..................................................
29 ..................................................
Minimum .................................
Arithmetic Mean .....................
Maximum ................................
Difference
between
Tsu,f and T24
(°F)
T24
(°F)
Tsu,f
(°F)
Draw pattern
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
GS
GS
GS
GS
Low ...............................................
Medium .........................................
Medium .........................................
Medium .........................................
Medium .........................................
Medium .........................................
Medium .........................................
Low ...............................................
Medium .........................................
Medium .........................................
High ..............................................
Low ...............................................
Medium .........................................
Medium .........................................
Medium .........................................
Medium .........................................
Medium .........................................
Low ...............................................
Medium .........................................
Medium .........................................
Medium .........................................
Medium .........................................
Medium .........................................
Medium .........................................
Low ...............................................
Medium .........................................
High ..............................................
Medium .........................................
High ..............................................
125.2
121.2
124.2
122.7
120.2
123.7
120.1
121.7
124.2
127.1
124.4
123.4
121.1
121.5
117.4
117.5
125.1
121.3
119.5
122.7
116.3
112.8
126.0
124.9
124.1
125.7
125.7
125.4
128.9
127.9
116.7
123.8
122.1
121.6
120.7
119.5
122.5
117.8
126.8
122.9
120.6
116.0
119.5
119.8
123.9
124.2
120.4
119.4
114.5
124.5
118.2
135.8
122.7
122.4
126.3
126.3
132.8
130.6
2.72
4.50
0.40
0.56
1.44
3.04
0.60
0.78
6.42
0.27
1.54
2.83
5.13
1.96
2.42
6.43
0.93
0.91
0.10
8.17
8.16
5.38
9.83
2.22
1.72
0.60
0.60
7.40
1.70
...............................
...............................
...............................
.......................................................
.......................................................
.......................................................
........................
........................
........................
........................
........................
........................
0.10
3.06
9.83
* Note: ‘‘ES’’ denotes an electric storage water heater, and ‘‘GS’’ denotes a gas-fired storage water heater.
TABLE III.3—T0, Tmax,1, AND Tsu,0 VALUES FOR WATER HEATERS TESTED BY DOE
lotter on DSK11XQN23PROD with RULES2
Test No.
1 ......................................
2 ......................................
3 ......................................
4 ......................................
5 ......................................
6 ......................................
7 ......................................
8 ......................................
9 ......................................
10 ....................................
11 ....................................
12 ....................................
13 ....................................
14 ....................................
15 ....................................
16 ....................................
17 ....................................
18 ....................................
19 ....................................
20 ....................................
21 ....................................
22 ....................................
23 ....................................
24 ....................................
25 ....................................
VerDate Sep<11>2014
Product type *
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
19:48 Jun 20, 2023
T0
(°F)
Draw pattern
Low .................................
Medium ...........................
Medium ...........................
Medium ...........................
Medium ...........................
Medium ...........................
Medium ...........................
Low .................................
Medium ...........................
Medium ...........................
High ................................
Low .................................
Medium ...........................
Medium ...........................
Medium ...........................
Medium ...........................
Medium ...........................
Low .................................
Medium ...........................
Medium ...........................
Medium ...........................
Medium ...........................
Medium ...........................
Medium ...........................
Low .................................
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Tmax,1
(°F)
118.2
117.1
119.0
118.3
124.2
117.7
119.2
122.0
124.4
122.4
120.8
123.8
116.8
120.8
121.8
120.6
121.1
121.0
122.5
120.1
124.5
122.7
125.6
124.6
123.4
E:\FR\FM\21JNR2.SGM
116.8
119.8
116.0
119.6
117.8
118.7
116.2
117.1
121.3
120.5
121.1
120.7
121.9
126.0
121.2
121.8
118.6
121.4
115.3
124.1
116.7
113.6
120.4
124.4
118.4
21JNR2
Tsu,0
(°F)
114.0
120.2
119.6
120.2
119.5
119.8
117.5
115.6
121.1
122.5
122.7
124.5
119.5
125.2
121.6
122.6
121.4
118.6
116.5
125.8
118.8
114.9
122.2
125.4
119.1
Maximum
difference
between
T0 Tmax,1
and Tsu,0
(°F)
4.20
3.07
3.60
1.95
6.36
2.13
3.02
6.40
3.33
2.00
1.91
3.80
5.13
5.17
0.56
1.98
2.80
2.80
7.20
5.75
7.80
9.05
5.23
1.00
4.97
Federal Register / Vol. 88, No. 118 / Wednesday, June 21, 2023 / Rules and Regulations
40457
TABLE III.3—T0, Tmax,1, AND Tsu,0 VALUES FOR WATER HEATERS TESTED BY DOE—Continued
Test No.
26
27
28
29
....................................
....................................
....................................
....................................
Minimum ...................
Arithmetic Mean .......
Maximum ..................
Product type *
T0
(°F)
Draw pattern
Tsu,0
(°F)
Tmax,1
(°F)
Maximum
difference
between
T0 Tmax,1
and Tsu,0
(°F)
GS
GS
GS
GS
Medium ...........................
High ................................
Medium ...........................
High ................................
125.0
126.1
124.1
124.7
126.0
125.2
128.7
123.8
128.0
131.8
131.4
129.8
3.00
6.60
7.30
6.00
...............................
...............................
...............................
.........................................
.........................................
.........................................
........................
........................
........................
........................
........................
........................
........................
........................
........................
0.5656
4.28
9.05
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* Note: ‘‘ES’’ denotes an electric storage water heater, and ‘‘GS’’ denotes a gas-fired storage water heater.
On average, across multiple product
classes, the temperatures Tsu,f and T24
vary about 3 °F from each other.
Similarly, the temperatures T0, Tmax,1,
and Tsu,0 vary about 4 °F from for each
other. In both cases, the range of
variability between the mean tank
temperatures of the water heaters in the
sample was from less than 1 °F up to
9 °F. Based on these data, DOE has
concluded that both the temperatures
are similar enough among each other
that grouping them together for
determining internal storage tank
temperature, as proposed in the July
2022 SNOPR, is reasonably valid when
there is no direct alternative of
measuring these temperatures. As such,
in this final rule, DOE is adopting the
method for determining internal storage
tank temperature as proposed in the July
2022 SNOPR with the modifications
discussed in the preceding paragraphs.
In response to Rheem’s request for a
derivation of the Tst equation, DOE
notes that it was derived based on the
assumption that the withdrawn water
has the same amount of energy as the
water stored in the tank, since there
would be no energy input (i.e., the
burner, compressor, and/or electrical
heating elements are deactivated) and
assuming minimal losses over the
course of the draw. Specifically, DOE
sought to determine the initial mean
tank temperature of the water, denoted
by Tst. The energy in the withdrawn
water can be calculated based on its
mass, specific heat, and the temperature
difference between the water and the
ambient air, which are all parameters
that can be measured or determined
directly as the water is being withdrawn
from the tank. As noted previously, this
value can then be assumed to be equal
to the energy that would have been
stored in the tank before withdrawing
the water, which can also be determined
based on its mass, specific heat, and
temperature difference. The mass of
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water in the tank can be determined
based on the stored volume and density;
the specific heat can be assumed as 1
Btu/lb°F, and the temperature difference
can be calculated as Tst. minus the
ambient temperature. As Tst is the only
unknown, the equation can be
rearranged to solve for Tst to provide an
estimate of the mean tank temperature
prior to withdrawing water.
In response to requests made by
AHRI, A.O. Smith, and BWC for
additional time to conduct testing, DOE
reiterates that test procedures must be
established for all products within the
scope of this rulemaking. DOE is
finalizing this method for determining
internal tank temperature based on an
evaluation of its own test data, and the
Department does not believe it is
necessary to delay publication of this
final rule for additional data to be
collected on this topic. Water heaters
with rated storage volumes greater than
or equal to 2 gallons whose internal tank
temperatures cannot be measured using
thermocouples meet the definition of
‘‘consumer water heater’’ as codified at
10 CFR 430.2; therefore, they are
covered products and must have
applicable test procedures. In this case,
based on information from its own
testing, DOE is establishing these test
procedures in this final rule.
8. Alternate Order 24-Hour SimulatedUse Test
As discussed in the January 2022
NOPR, DOE received comments at the
RFI stage from SMTI recommending that
DOE move the standby loss period of
the test to the beginning of the 24-hour
simulated-use test and to start the first
draw at the 6-hour mark, based on
claims that water heaters with large
storage volumes but low input rates
(e.g., storage-type heat pump water
heaters) may receive artificially low
recovery efficiency results from the
current test method with the standby
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loss period occurring in the middle of
the test. 87 FR 1554, 1587 (Jan. 11,
2022).
In the January 2022 NOPR, DOE noted
that as a general matter, the result of the
standby period has a negligible effect on
UEF, so moving the standby period to
the start of the rest would likewise have
a negligible effect on UEF in terms of
improving the accuracy of the standby
loss calculations for most water heaters.
However, DOE agreed that moving the
standby period to the start of the test
may affect the recovery efficiency of the
large-volume/low-input-rate water
heaters described by SMTI, and a large
change in recovery efficiency can have
a significant effect on UEF. DOE
tentatively determined that the first
recovery is rarely delayed past the first
draw (based on DOE’s own test data),
but if the order of the 24-hour
simulated-use test were to be changed
(i.e., placing the standby loss period at
the beginning), all water heaters on the
market would need to be retested.
Therefore, DOE declined to propose
such a change, as the associated burden
on manufacturers to retest would result
in a potential increase in accuracy for
only a small subset of the consumer
water heaters available on the market.
87 FR 1554, 1587 (Jan. 11, 2022).
DOE did not receive further
comments on this topic. Therefore, DOE
has decided not to move the standby
period to the start of the 24-hour
simulated-use test because such
amendment would be unduly
burdensome on all manufacturers, as
they would be required to retest all of
their products, even though the
representativeness of the efficiency
results would be improved for only a
small subset of water heaters.
F. Computations
1. Mass Calculations
In sections 6.3.5 and 6.4.2 of
appendix E, the mass withdrawn during
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21JNR2
Federal Register / Vol. 88, No. 118 / Wednesday, June 21, 2023 / Rules and Regulations
each draw (Mi) is used to calculate the
daily energy consumption of the heated
water at the measured average
temperature rise across the water heater
(QHW). However, neither section
includes a description of how to
calculate the mass withdrawn for tests
in which the mass is indirectly
determined using density and volume
measurements. In the April 2020 RFI,
DOE requested feedback on whether to
update the consumer water heater test
procedure to include a description of
how to calculate the mass withdrawn
from each draw in cases where mass is
indirectly determined using density and
volume measurements. 85 FR 21104,
21113 (April 16, 2020). Stakeholders
generally supported including an
equation in the computations of
appendix E, with many suggesting that
DOE adopt the calculations in the AHRI
Operations Manual for Residential
Water Heater Certification Program. 87
FR 1554, 1582 (Jan. 11, 2022).
In the January 2022 NOPR, DOE
proposed that the volume at the outlet
would be multiplied by the density,
which would be based on the average
outlet temperature measured during the
draw. DOE also proposed to add
procedures similar to those in the AHRI
Operations Manual for Residential
Water Heater Certification Program; in
particular, DOE proposed to add a
method of converting inlet water
volume to outlet water volume using the
ratio of the water densities at the inlet
and outlet.75 Id.
In response to the January 2022
NOPR, BWC supported DOE’s proposed
clarifications for calculating water mass
from indirect measurements. (BWC, No.
33 at p. 8)
After carefully considering the
comments, in this final rule, DOE is
adopting the computations for
determining water mass from indirect
measurements that were proposed in the
January 2022 NOPR for the reasons
previously discussed.
Where:
kV is the dimensionless volume scaling
factor;
r(T) is the density of water evaluated at
temperature T;
CP(T) is the heat capacity of water evaluated
at temperature T;
Tmax,1 is the maximum measured mean tank
temperature after the first recovery
period of the 24-hour simulated-use test,
and
67.5 °F is the average ambient temperature.
75 The AHRI Operations Manual for Residential
Water Heater Certification Program specifies that
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2. Effective Storage Volume
In this final rule, DOE is establishing
provisions to calculate the effective
storage volume to account for: (1) water
heaters which may increase storage tank
temperature to increase delivery
capacity, and (2) circulating water
heaters. As discussed throughout
section III.E.1 of this document, raising
the temperature of the water stored in
the tank can increase the effective
storage capacity of the water heater.
Additionally, circulating water heaters
are instantaneous-type water heaters
that operate with a separate stored
volume of water such that the actual
amount of hot water that can be
provided immediately (without
additional heat input) is related to the
volume of water stored in the
circulation pipes or in the separate
tank—and not the rated storage volume
of the circulating water heater itself. The
following subsections describe the
approach used for each case.
a. Storage Water Heaters With Elevated
Stored Water Temperature
In the July 2022 SNOPR, DOE
addressed multiple comments regarding
water heaters which boost the tank
temperature in order to increase
effective storage volume. (Operation in
high heat mode and high temperature
testing are discussed in detail in section
III.E.1 of this final rule.) In particular,
DOE noted there are certain consumer
activities, such as filling a bathtub, for
which the FHR metric and the rated
storage volume metric alone do not
sufficiently describe the water heater’s
ability to provide a large amount of hot
water immediately. 87 FR 42270,
42280–42281 (July 14, 2022).
For activities such as filling a bathtub,
consumers would benefit more from
87 FR 42270, 42281 (July 14, 2022).
DOE proposed to determine the
effective storage volume by multiplying
the measured storage volume by kV. Id.
In response to DOE’s effective storage
volume proposal, ASAP, ACEEE, and
NRDC expressed support for DOE’s
the outlet water volume is equal to the inlet water
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knowing the effective storage volume
(i.e., the volume of immediately
available hot water) of a water heater,
whereas for activities such as taking a
shower, consumers could benefit more
from knowing the FHR (i.e., ability to
deliver hot water for an extended period
of time). In particular, FHR represents
one full hour of delivery and does not
necessarily describe immediate hot
water availability, as FHR is also
impacted by the rate of recovery. In the
past, rated storage volume has served as
an indication of the amount of hot water
immediately available. However, given
the emergence of new water heater
designs that allow operation in high
heat mode, and the option that has
existed to increase the tank temperature
and install an external mixing valve, to
provide additional capacity, this is no
longer the case for all water heaters.
Hence, in addition to FHR, DOE
tentatively determined in the July 2022
SNOPR that effective storage volume
would be a meaningful performance
metric for consumers. Id.
Therefore, in the July 2022 SNOPR,
DOE proposed a method to determine
effective storage volume, Veff (expressed
in gallons or liters), at section 6.3.1.1 of
appendix E. For water heaters capable of
operating in high heat mode (which
DOE proposed be determined by Tmax,1
being greater than Tdel,2 during the 24hour simulated use test), DOE proposed
to calculate the effective storage volume
based on a volume scaling factor and
data already collected during the
appendix E test. Id. at 87 FR 42281.
DOE proposed that the volume scaling
factor would be determined as follows,
which is derived by comparing the
thermal energy stored by the water
heater when the water is heated to
125 °F to the thermal energy stored at its
maximum tank temperature, using
temperature data collected during the
test:
proposal to use effective storage volume
as a metric for water heaters with high
heat modes. (ASAP, ACEEE, and NRDC,
No. 54 at pp. 2–3)
AHRI requested that DOE provide
additional data and evidence supporting
the proposed equations for calculating
effective storage volume and stated that
manufacturers would also need
volume times the inlet water density divided by the
outlet water density.
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additional time to complete testing to
verify their accuracy,
representativeness, and repeatability.
AHRI requested that DOE specify the
correct procedure to evaluate this metric
where the initial recovery period
extends beyond the start of the second
draw in this test. (AHRI, No. 55 at pp.
7–8)
BWC requested that DOE conduct
further testing for the method to
determine effective storage volume,
stating that manufacturers have not had
enough time to conduct their own
testing for this proposal. (BWC, No. 48
at pp. 3–4)
Rheem suggested that DOE may not
have enough information to incorporate
effective storage volume into its energy
conservation standards rulemaking
without amending certification criteria
because DOE is not requiring it to be
reported. (Rheem, No. 47 at p. 8)
Additionally, Rheem stated that models
without ‘‘high heat modes’’ may still
meet the conditions to be affected by the
effective storage volume calculation,
and the commenter requested that DOE
clarify how to calculate effective storage
volume when the first recovery period
extends beyond the second draw,
raising the concern that the delivery
temperature can be too low as a result
of this condition. (Rheem, No. 47 at p.
7)
In order to address these comments,
DOE has re-evaluated its own test data
to further examine the implications of
the effective storage volume calculation
40459
as proposed in the July 2022 SNOPR. In
particular, DOE sought to address
Rheem’s concern that the criteria which
triggers effective storage volume
calculation (Tmax,1 > Tdel,2) may lead
more models to be impacted than just
those operating with an elevated tank
temperature and the request for
clarification on how to calculate
effective storage volume in the instance
that the first recovery period extends
beyond the second draw. Table III.3 lists
the anonymized test data DOE evaluated
to address the first of these two
concerns. These tests were conducted in
accordance with the currently
applicable appendix E test procedure,
with a nominal setpoint temperature of
125 °F and no mixing valve installed.
TABLE III.3—Tmax,1 AND Tdel,2 VALUES FOR A SAMPLE OF WATER HEATERS
Test No.
1
2
3
4
5
6
7
8
...........................................
...........................................
...........................................
...........................................
...........................................
...........................................
...........................................
...........................................
Minimum .......................
Mean .............................
Maximum ......................
Std. Dev ........................
Product type *
Draw pattern
ES
ES
ES
ES
GS
GS
GS
GS
...............................
...............................
...............................
...............................
Medium ................................
Medium ................................
Medium ................................
Medium ................................
Medium ................................
High .....................................
Medium ................................
High .....................................
..............................................
..............................................
..............................................
..............................................
Tmax,1
(°F)
Tdel,2
(°F)
116.0
117.8
121.3
120.4
126.0
125.2
128.7
123.8
116.0
122.4
128.7
4.3
Tmax,1¥Tdel,2
(°F) **
124.6
125.8
122.8
122.6
128.5
127.2
129.5
127.0
........................
........................
........................
........................
¥8.6
¥8.0
¥1.5
¥2.2
¥2.5
¥2.0
¥0.8
¥3.2
¥8.6
¥3.6
¥0.8
3.0
kv > 1 †
NO.
NO.
NO.
NO.
NO.
NO.
NO.
NO.
lotter on DSK11XQN23PROD with RULES2
* Note: ‘‘ES’’ denotes an electric storage water heater, and ‘‘GS’’ denotes a gas-fired storage water heater.
** A value of +5 °F or more in this column would satisfy one of the two criteria for determining kV to be greater than 1.
† Per the effective storage volume calculation provisions established in this final rule.
Upon further evaluation of the test
data presented in Table III.3 and based
on comments received, in this final rule,
DOE is modifying the approach in its
earlier proposal to ensure that kV values
greater than 1 are only calculated for
water heaters operating with a
significantly elevated tank
temperature—as determined by both the
difference between the storage tank
temperature and the delivery
temperature, as well as the storage tank
temperature itself. Specifically, due to
the fact that for some of the water
heaters in Table III.3 Tmax,1 is only
slightly less than Tdel,2, DOE has
amended the criteria for determining kV
such that a water heater must have both
Tmax,1 > 130 °F and Tmax,1 > Tdel,2 + 5 °F
in order to have a kV factor greater than
1. If these two criteria are not met, then
the water heater will be assigned a kV
factor of 1 and will have an effective
storage volume equal to its rated storage
volume. This update to DOE’s proposed
approach will ensure that effective
storage volume is only calculated to be
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greater than the rated storage volume for
water heaters operating with a mean
tank temperature that is both
significantly above 125 °F and
significantly above the delivered water
temperature. The data show that for
tests conducted at a nominal 125 °F tank
temperature setpoint, a kV greater than
1.0 is not expected. For additional
reference, DOE conducted one test on a
water heater set to its maximum storage
tank temperature, resulting in a Tmax,1 of
159.6 °F and a Tdel,2 of 124.3 °F, which
would cause the kV to be equal to 1.59.
Additionally, in order to address
Rheem’s concern about models for
which the first recovery period extends
beyond the start of the second draw,
DOE has examined its own test data for
water heaters exhibiting this behavior.
Table III.4 lists anonymized data from
21 tests for which the first recovery
period extended beyond the start of the
second draw. Similar to the previous
dataset, these tests were conducted at a
tank temperature setpoint of 125 °F and
no mixing valve installed.
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DOE agrees that it would not be
appropriate to base the effective storage
volume calculation criteria on Tdel,2 if
the tank is still recovering during the
second draw, because Tdel,2 may be
lower than it would be had the tank
fully recovered. Therefore, for such
cases, DOE has determined that T0 will
take the place of Tmax,1, and Tdel,1 will
take the place of Tdel,2 in the criteria
specified previously. DOE has specified
T0 and Tdel,1 as substitutes in this
instance because they are unaffected by
the timing of the first recovery period.
Tdel,1 is measured during the first draw
of the test, which will begin prior to the
start of a recovery. T0 is measured
immediately before the first draw
(during which Tdel,1 is measured) and
before the first recovery period, and it
is, therefore, more representative of
internal tank temperature as a point of
comparison with Tdel,1 to determine
whether the storage tank temperature is
elevated relative to the delivery
temperature. In reviewing its data for
tests whose first recovery period
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extended into the second draw, as
shown in Table III.4, DOE found that the
results using T0 and Tdel,1 are very
comparable to those using Tmax,1 and
Tdel,2, as shown in Table III.3. However,
DOE is not making T0 and Tdel,1 the
default variables because when T0 is
paired with Tdel,1, the delta between the
two is a slightly less reliable indicator
of when elevated tank temperatures
actually occur, compared to the default
pair of Tmax,1 and Tdel,2. This is
evidenced by the fact that the standard
deviation of the delta, T0¥Tdel,1, is
slightly higher at 3.6, than that of the
default variables, Tmax,1¥Tdel,2, which is
3.0. These standard deviations, along
with other statistics for the test data are
shown in Table III.3 and Table III.4.
TABLE III.4—T0 AND Tdel,1 VALUES FOR A SAMPLE OF WATER HEATERS WHOSE FIRST RECOVERY PERIOD EXTENDS INTO
THE SECOND DRAW
Test No.
Product type
Draw pattern
1 ...........................................
2 ...........................................
3 ...........................................
4 ...........................................
5 ...........................................
6 ...........................................
7 ...........................................
8 ...........................................
9 ...........................................
10 .........................................
11 .........................................
12 .........................................
13 .........................................
14 .........................................
15 .........................................
16 .........................................
17 .........................................
18 .........................................
19 .........................................
20 .........................................
21 .........................................
Minimum .......................
Mean .............................
Maximum ......................
Std. Dev ........................
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
ES
...............................
...............................
...............................
...............................
Low ......................................
Medium ................................
Medium ................................
Medium ................................
Medium ................................
Low ......................................
Medium ................................
High .....................................
Low ......................................
Medium ................................
Medium ................................
Medium ................................
Medium ................................
Medium ................................
Low ......................................
Medium ................................
Medium ................................
Medium ................................
Medium ................................
Medium ................................
Low ......................................
..............................................
..............................................
..............................................
..............................................
T0
(°F)
Tdel,1
(°F)
118.2
117.1
118.3
117.7
119.2
122.0
122.4
120.8
123.8
116.8
120.8
121.8
120.6
121.1
121.0
122.5
120.1
124.5
122.7
124.6
123.4
116.8
120.9
124.6
2.4
122.8
128.7
123.7
127.7
125.9
125.2
128.3
126.8
125.6
129.5
123.8
123.9
123.1
126.6
125.0
125.3
129.0
125.0
124.3
126.3
123.0
........................
........................
........................
........................
T0¥Tdel,1
(°F) **
¥4.6
¥11.6
¥5.5
¥10.0
¥6.7
¥3.2
¥6.0
¥6.0
¥1.8
¥12.7
¥3.0
¥2.1
¥2.5
¥5.5
¥4.0
¥2.8
¥9.0
¥0.5
¥1.6
¥1.7
0.4
¥12.7
¥4.8
0.4
3.6
kv > 1 †
NO.
NO.
NO.
NO.
NO.
NO.
NO.
NO.
NO.
NO.
NO.
NO.
NO.
NO.
NO.
NO.
NO.
NO.
NO.
NO.
NO.
lotter on DSK11XQN23PROD with RULES2
* Note: ‘‘ES’’ denotes an electric storage water heater.
** A value of +5 °F or more in this column would satisfy one of the two criteria for initiating calculation of kV.
† Per the effective storage volume calculation provisions established in this final rule.
AHRI, A.O. Smith, and Rheem
expressed concern that because FHR is
used as a metric for other activities such
as building codes, plumbing codes, and
incentive programs, DOE’s proposal
may cause misalignment with those
requirements, as well as increased
burden if manufacturers were to be
required to comply with metrics for
both FHR and effective storage volume.
(AHRI, No. 55 at p. 7; A.O. Smith, No.
51 at pp. 7–8; Rheem, No. 47 at pp. 7–
8) Rheem suggested that effective
storage volume is not more appropriate
than FHR as a metric of thermal energy
storage. (Rheem, No. 47 at p. 7) A.O.
Smith and Rheem also suggested that
FHR is a more meaningful metric for
consumers and that effective storage
volume would be confusing. (A.O.
Smith, No. 51 at pp. 7–8; Rheem, No. 47
at p. 7)
In response to these comments, the
Department confirms that FHR is not
being phased out or fully replaced by
effective storage volume in the DOE test
procedure, and, therefore, this
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additional metric will not cause
misalignment with other programs and
regulations based on FHR. As stated
previously, these metrics provide
different information: effective storage
volume indicates the amount of hot
water that can be delivered immediately
without need for heat input and is
correlated to the standby losses of the
tank, whereas the FHR metric is
determined by a test which allows the
heat input to remain on and for the
water heater to initiate a recovery.
Additionally, manufacturer burden
would be minimal because the effective
storage volume can be determined based
on measurements already taken during
the 24-hour simulated use test.
DOE notes that in contrast to FHR,
effective storage volume is capable of
accounting for the increase in thermal
energy associated with heating water
above the intended delivery temperature
in comparison with larger units storing
water at conventional temperatures. It
also allows consumers to compare water
heaters with similar delivery
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capabilities but different sizes,
information which DOE considers
meaningful, while avoiding the risk of
backsliding for units with lower-thannormal FHRs, should FHR be used as
the metric. Contrary to what these
commenters suggest, DOE finds that
providing a measure of effective storage
volume is more likely to prevent
consumer confusion due to the
increased transparency it promotes by
reflecting the immediate hot water
capacity of the water heater for certain
uses such as filling a bathtub. Combined
with the high temperature test method,
consumers would have a way to directly
compare the performance of water
heaters of different sizes that can meet
the same user needs.
In response to DOE’s request for
comment regarding its proposed
equations and approach to calculate
effective storage volume, Rheem agreed
that DOE’s derivation from an energy
balance was appropriate for calculating
a scaling factor. (Rheem, No. 47 at p. 7)
NEEA commented that that the
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proposed method appears to contain an
error in the calculation of the
dimensionless volume scaling factor
(kv,) by using 67.5 °F, the standard test
condition ambient air temperature,
instead of 58 °F, the standard test
condition water inlet temperature.
Otherwise, NEEA indicated support of
DOE’s proposed method for calculating
the effective storage volume metric.
(NEEA, No. 56 at p. 3)
DOE’s volume scaling factor is
derived by comparing the thermal
energy stored by the water heater when
the water is heated to 125 °F to the
thermal energy stored at its maximum
tank temperature. In response to NEEA’s
comment, DOE notes that the method to
calculate the dimensionless volume
scaling factor kv uses ambient air
temperature because as the water in the
storage tank cools, heat is lost to the
surrounding air. Thus, the water
approaches the temperature of the
surrounding air, not the 58 °F inlet
water temperature. Therefore, DOE has
maintained this calculation method as
originally proposed.
Rheem suggested that an effective
volume scaled to 125 °F is not useful for
customers because a typical bath
temperature is around 100 °F. (Rheem,
No. 47 at p. 7) In response, DOE notes
that the effective storage volume
calculation is to show how much
additional thermal energy is stored in
the tank compared to a water heater
which is not raising the internal tank
temperature beyond the delivery
temperature. Because 125 °F is the
delivery setpoint temperature used in
the appendix E test procedure as being
representative of typical water heater
setpoint temperatures, DOE has
concluded that it is appropriate for the
tank temperature has to be compared to
125 °F.
The CA IOUs supported DOE’s
proposed effective storage volume
metric as being more representative of a
storage water heater’s hot water delivery
capacity than rated storage volume.
However, the CA IOUs asserted that
effective storage volume does not
account for differences in recovery rate
between water heaters, a factor which
also affects hot water delivery capacity
and specifically FHR. The CA IOUs
pointed out that large discrepancies in
FHR exist within a given rated storage
volume for both gas and electric storage
water heaters. Therefore, the CA IOUs
suggested DOE should revise its
proposed algorithm for the effective
storage volume to produce a metric
incorporating the volume and
temperature of the stored water and the
water heater recovery rate. (CA IOUs,
No. 52 at pp. 2–4)
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In response, effective storage volume
is intended to measure the maximum
thermal energy a water heater can store
and to indicate the amount of hot water
that is immediately available. Effective
storage volume is not intended to
measure how fast the unit is able to heat
water. This is in contrast with FHR,
which accounts for the water heater’s
recovery rate as previously described.
Accounting for water heater recovery
rate in the effective storage volume
calculation would make the effective
storage volume metric duplicative of the
existing FHR metric; DOE reiterates that
effective storage volume will not replace
FHR, which will remain a part of the
test procedure. A.O. Smith stated that
the effective storage volume metric may
become obsolete if DOE’s proposed
energy conservation standards
effectively limit the availability of nondemand response water heaters with
user-selectable high heat modes. (A.O.
Smith, No. 51 at p. 7) In response to
A.O. Smith’s comment, DOE notes that
the scope of this comment falls within
that of the energy conservation
standards rulemaking, so it will be
properly considered in the concurrent
standards rulemaking for consumer
water heaters. Additionally, DOE would
again mention that certification and
representations of effective storage
volume will not be required as a result
of this final rule, but instead may be
required at the time of any energy
conservation standards that specifically
address which water heaters may be
required to carry out high temperature
testing.
Finally, when proposing the
calculation of estimated mean tank
temperature in the July 2022 SNOPR,
DOE inadvertently omitted the
calculation of annual electrical energy
consumption from the test procedure.
DOE has once again included this
calculation as originally proposed in the
January 2022 NOPR at section 6.3.10 of
appendix E.
b. Circulating Water Heaters
As discussed in section III.D.4 of this
document, DOE is amending the test
procedure to require that circulating
water heaters must be tested with a
separate storage tank. Specifically, gasfired and oil-fired circulating water
heaters and electric resistance
circulating water heaters must be tested
with an UFHWST, and heat pump-type
circulating water heaters must be tested
with an electric storage water heater.
For circulating water heaters, effective
storage volume calculations will be
carried out in a slightly different
manner than for storage water heaters.
The methodology established in this
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40461
final rule takes into consideration the
concerns raised by stakeholders and
discussed in section III.D.4 of this
document. In summary, while
commenters expressed that it would be
beneficial to be able to use a range of
UFHWST volumes for testing non-heatpump-type circulating water heaters,
commenters were also concerned that
the results of testing may not be
reproducible without certifying the
specific model of UFHWST to be used.
Regarding the volume, DOE understands
that circulating water heater designs
may be optimized to operate with
specific storage volumes; thus, in this
final rule, DOE is allowing a range of
volumes to be used. However,
manufacturers may represent the
volume of the UFHWST in terms of the
effective storage volume of the
circulating water heater as follows.
Because circulating water heaters are
to be tested with a separate storage tank,
they operate, as a system, in a similar
manner to storage-type water heaters.
Although the volume stored by the
circulating water heater itself may be
small, these water heaters require a
separate volume of water to operate
properly. Therefore, DOE has
determined that it is appropriate for the
effective storage volume calculation for
circulating water heaters to account for
the separate storage tank, as the volume
of the stored water is representative of
the effective volume that would be
available for such a water heater in the
field, since it is necessary to install a
circulating water heater with a storage
tank or other stored volume of water.
The procedure for calculating effective
storage volume of separate storage tanks
paired with circulating water heaters is
outlined in section 6.3.1.1 of appendix
E. This procedure will prescribe the
value of the measured storage volume of
the separate storage tank to be the
effective storage volume of the
circulating water heater, and the
measured storage volume of the separate
storage tank shall be determined in
accordance with section 5.2.1 of the
amended appendix E (Determination of
Storage Tank Volume). This allows the
same method of volume measurement to
be applied to UFHWSTs and separate
electric resistance storage tanks. DOE
has determined that this approach
allows for manufacturers to have the
flexibility to use the appropriate size of
UFHWST for the circulating water
heater while still ensuring that testing
can be done in a reproducible manner.
In a separate rulemaking pertaining to
certification requirements for consumer
water heaters and residential-duty
commercial water heaters, DOE will
address any potential amendments
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which would need to be made in order
to certify the effective storage volume of
a product. DOE would consider
establishing product-specific
enforcement provisions for circulating
water heaters at such a time when
energy conservation standards for these
products are evaluated.
G. Untested Provisions (Alternative
Efficiency Determination Methods)
At 10 CFR 429.70, DOE specifies
alternative methods for determining
energy efficiency and energy use for
certain covered products and
equipment, including consumer water
heaters.76 In general, these provisions
allow a manufacturer to determine the
energy efficiency or energy use of a
basic model using an alternative
efficiency determination method
(AEDM) in lieu of actually testing the
basic model. Specific to each product or
equipment type covered by these AEDM
provisions, DOE defines the criteria for
using an AEDM and, for some products
and equipment, procedures to be used
to validate an AEDM and to perform
verification testing on units certified
using an AEDM.
The provisions at 10 CFR 429.70(g)
provide alternative methods for
determining ratings for ‘‘untested’’ basic
models of residential water heaters and
residential-duty commercial water
heaters. For models of water heaters that
differ only in fuel type or power input,
these provisions allow manufacturers to
establish ratings for untested basic
models based on the ratings of tested
basic models if certain prescribed
requirements are met. (Simulations or
other modeling predictions or ratings of
UEF, volume, first-hour rating, or
maximum gallons per minute are not
permitted (10 CFR 429.70(g)).)
Specifically, for gas water heaters, the
provisions at 10 CFR 429.70(g)(1)
specify that for untested basic models of
gas-fired water heaters that differ from
tested basic models only in whether the
basic models use natural gas or propane
gas, the represented value of UEF, FHR,
and maximum gallons per minute for an
untested basic model can be the same as
those for a tested basic model, as long
as the input ratings of the tested and
untested basic models are within ±10
percent.
For electric storage water heaters, the
provisions at 10 CFR 429.70(g)(2)
specify rating an untested basic model
using the FHR and the UEF obtained
from a tested basic model as a basis for
ratings of basic models with other input
76 Section 429.71 uses the term ‘‘residential,’’,
which is synonymous with the use of the term
‘‘consumer’’ in this document.
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ratings, provided that certain conditions
are met: (1) each heating element of the
untested basic model is rated at or above
the input rating for the corresponding
heating element of the tested basic
model; and (2) for an untested basic
model having any heating element with
an input rating that is lower than that
of the corresponding heating element in
the tested basic model, the FHR for the
untested basic model must result in the
same draw pattern specified in Table I
of appendix E for the simulated-use test
as was applied to the tested basic
model.77 10 CFR 429.70(g)(2)(i)–(ii).
In commenting on this topic in
response to the January 2022 NOPR,
Rheem suggested expanding the AEDM
provisions for consumer water heaters
to address circulating water heaters.
Specifically, Rheem identified three
possible AEDM approaches: (1) test the
thermal efficiency or COP using the
commercial water heater test procedure
and use the result to calculate an
estimated UEF for various storage
capacities; (2) open the commercial
HVAC AEDM provisions at 10 CFR
429.70(c) to circulating consumer water
heaters; or (3) add provisions similar to
the current electric storage water heater
AEDM, where a change in draw pattern
would necessitate a new test. (Rheem,
No. 31 at pp. 3–4)
Further, DOE notes that although
manufacturers of consumer water
heaters are not authorized to use an
AEDM under 10 CFR 429.70(c) to
determine ratings for consumer water
heaters, as discussed, manufacturers
may determine UEF for certain models
using the methods specified under 10
CFR 429.70(g). These models include:
(1) gas-fired basic models differing only
in whether the basic models use natural
gas or propane and with an input rating
within 10 percent and (2) electric
storage water heater basic models
differing only in heating element input
rating (in addition, for untested basic
models with a heating element with an
input rating that is lower than the input
rating of the corresponding element in
the tested basic model, the FHR for the
untested basic model must also result in
the same draw pattern as was applied to
the tested basic model). These
77 To establish whether this condition is met, the
provisions at 10 CFR 429.70(g)(2)(ii) specify
determining the FHR for the tested and the untested
basic models in accordance with the procedure
described in section 5.3.3 of 10 CFR part 430,
subpart B, appendix E, and then comparing the
appropriate draw pattern specified in Table I of
appendix E for the FHR of the tested basic model
with that for the untested basic model. If this
condition is not met, then the untested basic model
must be tested and the appropriate sampling
provisions applied to determine its UEF in
accordance with appendix E.
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provisions already provide
manufacturers with some measure of an
alternative method of rating consumer
water heaters without testing every
model, and this alternative method
reduces manufacturer test burden.
Further, DOE explained in a 2013 final
rule pertaining to AEDMs that the
AEDM provisions extend to those
products or equipment which have
‘‘expensive or highly-customized basic
models.’’ 78 FR 79579, 79580 (Dec. 31,
2013). The current AEDM provisions for
commercial HVAC equipment
(including commercial water heaters, for
example) were in part the result of a
negotiated rulemaking effort by the
Appliance Standards and Rulemaking
Federal Advisory Committee (ASRAC)
in 2013. Id. Consumer water heaters
were not considered at the time.78 Id In
this rulemaking, DOE did not receive
comments indicating that these
conditions would apply for consumer
water heaters or residential-duty
commercial water heaters, and, hence,
DOE has determined that modelingbased AEDMs are not required at this
time. Additionally, the test method
adopted in this final rule has been
determined to be representative of
energy use over an average use cycle
without being unduly burdensome.
Given these factors, DOE is not
considering further expansion of the
AEDM provisions for water heaters
within the scope of this test procedure,
aside from applying the untested model
provisions to electric instantaneous
water heaters, as discussed in section
III.G.2 of this document. The following
sections discuss representations of the
FHR value of certain untested models
and the extension of the alternative
rating method to electric instantaneoustype water heaters.
1. Representations of First-Hour Ratings
for Untested Basic Models
The provisions at 10 CFR 429.70(g)
allow for an untested electric storage
water heater basic model with element
wattages less than a tested basic model
to use the FHR of the tested basic
model, provided that the untested basic
model’s FHR is in the same draw
pattern as the tested basic model. For an
untested basic model with an element
wattage that is lower than the tested
basic model’s, the tested FHR of the
untested basic model will generally be
less than the FHR of the tested basic
model. In such cases, using the tested
basic model’s FHR to represent the
untested model’s FHR may not be as
78 Working group meeting transcripts can be
found at www.regulations.gov under Docket No.
EERE–2013–BT–NOC–0023.
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representative as using the FHR value
directly determined from the untested
model (the FHR of the untested basic
model is determined pursuant to the
procedures in appendix E specifically
for the purpose of allowing use of the
tested basic model’s UEF rating).
Instead, using the untested basic
model’s measured FHR for
representation purposes, rather than the
tested model’s FHR (as currently
required), could increase the
representativeness of the certified FHR,
while potentially not increasing burden
on the manufacturer.
The January 2022 NOPR requested
comment on the potential to revise the
existing provisions at 10 CFR
429.70(g)(2)(ii) for electric storage water
heaters with element wattages less than
the tested basic model to require that
the represented FHR of the untested
model be the untested basic model’s
FHR as determined according to the
procedures at appendix E. Specifically,
DOE sought information on whether
manufacturers collect sufficient data to
establish a rated value of FHR based on
FHR testing for untested basic models,
subject to the sampling plan
requirements at 10 CFR 429.17 (i.e.,
whether manufacturers currently
measure the FHR of at least two units of
an untested basic model to ensure it is
in the same draw pattern bin as the
tested model). 87 FR 1554, 1587–1588
(Jan. 11, 2022).
In commenting on this issue, ASAP,
ACEEE, and NCLC supported revising
the untested provisions for storage water
heaters so that the first-hour ratings for
untested models are used for ratings.
Likewise, ASAP, ACEEE, and NCLC also
supported requiring that the represented
value of max GPM for untested electric
instantaneous water heaters be the
actual value determined for the untested
model. (ASAP, ACEEE, and NCLC, No.
34 at p. 3)
BWC offered a different view,
commenting that the current AEDM
provisions yield accurate results for
untested electric storage water heaters
with element wattages less than the
tested basic models. The company
stated that changing these provisions
would result in significant burden for
manufacturers without producing
significantly different results. BWC also
urged DOE to not apply the more
stringent AEDM requirements for
electric storage water heaters to electric
instantaneous water heaters. (BWC, No.
33 at pp. 10–11)
Similarly, AHRI raised concerns about
the increased burden associated with
the proposed additional requirements
for alternate electric storage water heater
input ratings. (AHRI, No. 40 at p. 3)
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AHRI indicated that, because the
sampling plan provisions at 10 CFR
429.17 are not currently required when
certifying untested models,
manufacturers would have to retest and
recertify untested models if DOE were to
adopt such requirements. (AHRI, No. 40
at pp. 5–6) A.O. Smith requested
additional clarity on exactly which
untested models would need to be
tested to confirm FHR ratings under the
proposed untested provisions. (A.O.
Smith, Jan. 27, 2022 Public Meeting
Transcript, No. 27 at pp. 48–49) A.O.
Smith claimed that the established
practice has been to evaluate untested
electric storage water heater tank inputs
to confirm that these models would
perform in the same draw pattern as the
tested model. A.O. Smith also stated
that certifying data for untested models
would be an extra testing burden for
manufacturers which have relied on the
procedures pursuant to alternative
methods for determining energy
efficiency and energy use to establish
the ratings, and, therefore, the
commenter recommended against the
Department changing the relevant data
collection methodology. (A.O. Smith,
No. 37 at pp. 4–5)
After consideration of the comments
and the additional burden that an
amendment relating to the FHR
representations for certain untested
water heaters would impose, DOE has
decided not to amend these provisions
at this time. However, DOE reiterates
that, per the current AEDM
requirements, manufacturers are
required to test the FHR of an untested
model prior to making a determination
as to whether or not the untested model
will fall under the same draw pattern as
the tested model. This determination
should not be made on the basis of
input rates alone. Manufacturers should
consult 10 CFR 429.70(g), which states,
‘‘simulations or other modeling
predictions for ratings of the uniform
energy factor, volume, first-hour rating,
or maximum gallons per minute (GPM)
are not permitted.’’ Furthermore, as a
clarification of the existing reporting
requirements, manufacturers using the
untested provisions to certify certain
water heater models to DOE must
identify these models as being tested to
an AEDM (see 10 CFR 429.17(b)(1),
which references 10 CFR 429.12).
2. Alternative Rating Method for Electric
Instantaneous Water Heaters
In the January 2022 NOPR, in
response to earlier stakeholder
comments, DOE proposed to expand the
untested provisions (described in detail
in section III.G.1 of this document) so as
to apply similar provisions to electric
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instantaneous water heaters. The
proposed expansion would allow
electric instantaneous water heaters and
electric storage water heaters to have
similar AEDM requirements. 87 FR
1554, 1588 (Jan. 11, 2022).
As discussed in further detail in the
January 2022 NOPR, because electric
instantaneous water heaters exhibit the
same trends in performance that justify
the use of an alternative rating
determination method for electric
storage water heaters, DOE tentatively
determined that extending the use of the
untested provisions to electric
instantaneous water heaters in 10 CFR
429.70(g) would maintain a
representative rating of these products’
energy efficiency, while reducing
manufacturer burden. Therefore, DOE
proposed to permit use of the untested
provisions for electric instantaneous
water heaters through newly proposed
provisions at 10 CFR 429.70(g)(3).
Specifically, the January 2022 NOPR
proposed that the criteria that currently
apply to electric storage water heaters at
10 CFR 429.70(g)(2) would apply to
electric instantaneous type water
heaters at 10 CFR 429.70(g)(3), with the
exceptions that: (1) The criteria for
electric instantaneous water heaters
would reference the maximum GPM
rather than the FHR, as FHR applies
only to storage water heaters; and (2) the
criteria for electric instantaneous water
heaters would reference the ‘‘input rate’’
rather than the ‘‘heating element’’ or
‘‘input rating for the corresponding
heating element.’’. 87 FR 1554, 1588
(Jan. 11, 2022).
On this topic, AHRI and A.O. Smith
expressed support for the inclusion of
electric instantaneous water heaters in
the untested provisions. (AHRI, No. 40
at pp. 5–6; A.O. Smith, No. 37 at p. 2)
Based upon its previous reasoning and
after considering the relevant
comments, DOE is adopting the
untested provisions for electric
instantaneous water heaters as proposed
in the January 2022 NOPR, with only a
minor modification.
Section III.H.1 of this document
discusses terminology used with respect
to storage vs. instantaneous and flowactivated vs. non-flow-activated water
heaters. Specifically, DOE has
determined that not all instantaneous
water heaters are flow-activated, and
also that storage water heaters do not
necessarily have to be non-flowactivated, either. As such, in this final
rule, DOE is amending the language in
all of the untested provisions (those
which currently exist and those which
are being newly established) such that
the delivery capacity metric may be
either FHR or Max GPM. This correction
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will harmonize the requirements at 10
CFR 429.70(g) with the test procedure,
which specifies that the Max GPM
metric is for flow-activated water
heaters, and the FHR metric is for all
others, regardless of the water heater’s
classification as storage-type or
instantaneous-type (see section 5.3 of
appendix E).
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H. Corrections and Clarifications
DOE is adopting certain corrections
and clarifications to the appendix E test
procedure that are intended to improve
the repeatability and reproducibility of
the test procedure. These changes are
described in more detail in the
subsections that follow.
1. Flow-Activated Terminology
In sections 5.3.3.1 and 5.3.3.2 of
appendix E, which describe general
requirements and draw initiation
criteria, respectively, for the FHR test,
the term ‘‘storage-type water heaters’’ is
used. However, the FHR test applies to
all water heaters that are not flowactivated, which includes non-flowactivated instantaneous water heaters.
In this rulemaking, DOE sought
feedback on updating the phrase
‘‘storage-type water heaters’’ in section
5.3.3 to ‘‘non-flow-activated water
heaters.’’ 85 FR 21104, 21112 (April 16,
2020). Multiple stakeholders provided
comments on the use of ‘‘flowactivated’’ and ‘‘non-flow-activated’’ in
response to the April 2020 RFI and the
January 2022 NOPR.
Initially, commenters such as AHRI
and some manufacturers stated that
there is no need to change the phrase
‘‘storage-type water heaters’’ in section
5.3.3 of appendix E. However, when
DOE submitted a comment to the
ASHRAE 118.2 drafting committee
suggesting the change from ‘‘storagetype’’ to ‘‘non-flow activated’’ in the
corresponding sections of ASHRAE
118.2, this change was accepted by the
committee and used in ASHRAE 118.2–
2022. Thus, DOE proposed to update the
terminology in the January 2022 NOPR
in an effort to align terminology with
that recognized by industry. 87 FR 1554,
1576 (Jan. 11, 2022).
Specifically, section 7.3.3.1 of
ASHRAE 118.2–2022 uses the term
‘‘non-flow-activated’’ water heaters,
whereas section 5.3.3.1 of the current
appendix E test procedure uses the term
‘‘storage-type’’ water heaters. Yet
section 7.3.3.2 of ASHRAE 118.2–2022
still uses the ‘‘storage-type’’ term that is
present in section 5.3.3.2 of appendix E.
By contrast, DOE’s proposal, as
delineated in the January 2022 NOPR,
would effectively ensure that language
related to the FHR test did not
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inadvertently narrow the scope of that
test to only storage-type water heaters
whenever the term ‘‘storage-type’’ was
used in this context.
On this topic, Rheem supported the
proposed amendments to the language
throughout appendix E to use ‘‘non-flow
activated’’ and ‘‘flow-activated,’’ and to
refer to water heaters with or without
storage volumes greater than 2 gallons
as such. Rheem stated that these
changes eliminate the storage or
instantaneous type language except
where helpful to navigate the appendix.
(Rheem, No. 31 at p. 2)
Many commenters expressed
confusion regarding DOE’s proposed
changes in terminology in appendix E,
however. At the public meeting webinar
for the January 2022 NOPR, AHRI
requested further explanation of the
intent behind the proposed terminology
update changing ‘‘storage-type’’ and
‘‘instantaneous-type’’ to ‘‘non-flowactivated’’ and ‘‘flow-activated,’’
especially since the proposed terms are
not used in EPCA. AHRI requested that
DOE clarify whether or not the
terminology change would have any
impact on testing. (AHRI, Jan. 27, 2022
Public Meeting Transcript, No. 27 at pp.
41–42) In its written comments, AHRI
stated that replacing the ‘‘instantaneoustype’’ and ‘‘storage-type’’ terminology
with ‘‘flow-activated’’ and ‘‘non-flow
activated’’ may cause confusion for the
test methods relevant to water heaters
larger than 20 gallons in rated storage
volume. AHRI suggested that DOE
should consider adding steps to the test
procedure to determine: (1) if a unit is
‘‘storage-type’’ or ‘‘instantaneous-type’’
and (2) if a unit is ‘‘flow-activated’’ or
‘‘non-flow activated.’’ (AHRI, No. 40 at
p. 4) BWC did not support a change
from the terms ‘‘storage-type’’ and
‘‘instantaneous-type’’ to ‘‘non-flowactivated’’ and ‘‘flow-activated’’ for
water heaters above 20 gallons, stating
that it would create confusion for
manufacturers and testing laboratories.
(BWC, No. 33 at p. 6)
AET commented that a flow-activated
electric instantaneous water heater will
need to be able to heat its stored volume
of water to the 67 °F temperature rise in
appendix E in no more than about 30
seconds based on a calculation of
recovery efficiency and flow rate. (AET,
No. 29 at pp. 3–5) However, DOE notes
that this calculation is only possible
because the recovery efficiency of an
electric resistance water heater is
defined as 98 percent in the appendix
E test procedure; the time criterion
would vary for other types of water
heaters.
Furthermore, AET commented that
DOE should be careful in its use of the
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term ‘‘instantaneous’’ water heater to
ensure the test procedure for these
products applies to all products which
have more than 4,000 Btu/h of input per
gallon of storage, adding that there are
instantaneous water heaters have
several gallons of storage capacity or are
thermostatically-activated (which
should be tested under a non-flowactivated test method). The commenter
stressed that water heaters should be
tested per the flow-activated or nonflow-activated test method based on
whether or not they are indeed flowactivated, and not whether they are
instantaneous-type or storage-type. AET
commented that a thermostaticallyactivated unit does not necessarily mean
that stored water is kept fully heated,
but rather that the rate of change of
temperature of stored water can be used
to indicate whether a flow is occurring,
and, therefore, the distinction between
flow-activation and non-flow-activation
(i.e., thermostatic activation) may be
difficult to make for water heaters with
very small volumes. AET claimed that
hybrid instantaneous water heaters
activated by both flow and water
temperature are under development,
and such appliances should be
addressed in the test procedure. AET
also noted that the largest possible
instantaneous-type gas-fired unit may
have up to 50 gallons of storage volume
per the codified definitions, and the
largest possible instantaneous-type oilfired unit may have up to 52.5 gallons
of storage volume. Additionally, AET
provided detailed comments indicating
that not all instantaneous water heaters
are flow-activated within the scope of
the standards of consumer water
heaters, so DOE should not use the
terms interchangeably. (AET, No. 29 at
pp. 2–6)
To clarify the intent of the January
2022 NOPR’s proposal: DOE agrees with
AET that the distinction between
storage-type water heaters and
instantaneous-type water heaters is
different from the distinction between
flow-activated water heaters and water
heaters with other activation schemes.
Comments from manufacturers seem to
indicate that there could be a
misconception that ‘‘instantaneous-type
water heater’’ and ‘‘flow-activated water
heater’’ are interchangeable, because
these comments opposed DOE’s
correction to remove the ‘‘storage-type’’
term from the description of the FHR
test and replace it with the ‘‘non-flowactivated’’ term; however, these terms
are not interchangeable. When a water
heater is referred to as ‘‘storage-type’’ or
‘‘instantaneous-type,’’ those terms
specifically refer to the ratio between
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the storage volume and the input rate.
These terms are defined in EPCA (see 42
U.S.C. 6291(27)(A) and (B)) and at 10
CFR 430.2. For example, DOE’s energy
conservation standards at 10 CFR
430.32(d) distinguish between storagetype and instantaneous-type water
heaters. Section 1.6 of appendix E
defines ‘‘flow-activated’’ as an
operational scheme in which a water
heater initiates and terminates heating
based on sensing flow in order to
determine which method of testing is
most appropriate for the water heater’s
operational scheme. Therefore, whether
a water heater is storage-type or
instantaneous-type has no bearing on
whether it is determined to be ‘‘flowactivated.’’ There. can be flow-activated
storage water heaters or even non-flowactivated instantaneous water heaters.
In fact, circulating water heaters are
defined as non-flow-activated
instantaneous water heaters (see section
III.A.4.a of this final rule).
Section 5.3.1 of appendix E states,
‘‘For flow-activated water heaters,
conduct the maximum GPM test, as
described in section 5.3.2, Maximum
GPM Rating Test for Flow-Activated
Water Heaters, of this appendix. For all
other water heaters, conduct the firsthour rating test as described in section
5.3.3 of this appendix.’’ In this final
rule, the Department is maintaining this
requirement in the revised appendix E
test procedure.
With respect to comments related to
how to determine whether a water
heater is flow activated, DOE has
concluded that the definition of ‘‘flowactivated’’ in proposed section 1.6 of
appendix E is sufficient for
manufacturers and testing laboratories
to determine whether a product meets
that definition. Specifically, if a water
heater initiates or terminates heating as
a result of sensing flow—regardless of
what type of sensor is used to determine
whether a flow is occurring—then the
water heater is flow-activated. If a water
heater has two activation schemes, one
of which is based on sensing flow (e.g.,
heating can also be initiated due to the
tank temperature crossing below a
certain thermostat limit), then it still
meets the description of a flow-activated
water heater, and, therefore, must be
tested as such. This is a clarification of
the current test procedure and not an
amendment, and, thus, DOE is
maintaining the language in the
definition of ‘‘flow-activated’’ in
appendix E (which will now appear at
section 1.7).
DOE understands that the term ‘‘nonflow-activated,’’ which was used in the
January 2022 NOPR’s proposal, could be
a source of confusion, because, as AET
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states, there are products which are
dually activated. Hence, in this final
rule, DOE is not introducing this term
into the appendix E test procedure.
Instead, DOE is striking out the
references to storage-type water heaters
in provisions related to water heaters
which require the FHR test and striking
out the reference to instantaneous-type
water heaters in provisions related to
water heaters which require the Max
GPM test. Because section 5.3.1 already
instructs which test is required, these
instances of the terms ‘‘storage-type’’
and ‘‘instantaneous-type’’ are inaccurate
and extraneous. DOE has determined
that these corrections and clarifications
do not change the way in which the
appendix E test procedure is conducted.
2. Second Identical 24-Hour SimulatedUse Test
For water heaters that are not flowactivated, the water heaters test
procedure in section 5.2.2.2 of the
currently applicable appendix E
includes directions for setting the
temperature controllers such that the
test method is repeatable and
reproducible.
A.O. Smith requested DOE to clarify
that, when testing water heaters larger
than or equal to 20 gallons, the second
identical simulated-use test is not a
requirement of the procedure but only a
means by which to validate the stability
of the setting, if it is deemed necessary
to perform. (A.O. Smith, No. 37 at p. 7)
In response, the Department notes
that there is no requirement for a second
identical 24-hour simulated-use test in
appendix E. Sections 5.2.2.2.1.1 and
5.2.2.2.1.2 of the currently applicable
test procedure states that once the
proper temperature control setting is
achieved, the setting must remain fixed
for the duration of the first-hour rating
test and the simulated-use test such that
a second identical simulated-use test
run immediately following the one
specified in section 5.4 would result in
average delivered water temperatures
that are within the bounds specified in
section 2.4 of this appendix. This
language was included to explain the
intent of the temperature control.
However, for units which have an
integrated mixing valve or that are
intended for use with a mixing valve,
the language describing the second
identical 24-hour simulated-use test
may be misleading, as there may be
individual draws where the outlet
temperature is outside the bounds
specified in section 2.4 of appendix E.
As a result, the Department is amending
the language to remove reference to a
second 24-hour simulated-use test. The
procedure to ensure the stability of the
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temperature control as described in
sections 5.2.2.2.1.1 and 5.2.2.2.1.2
remains unchanged.
3. Connected Products
Section 5.1 of appendix E currently
specifies the operational mode selection
for water heaters but does not explicitly
address ‘‘smart’’ or ‘‘connected’’ modes
of operation. For water heaters that
allow for multiple user-selected
operational modes, all procedures
specified in appendix E must be carried
out with the water heater in the same
operational mode (i.e., only one mode).
This operational mode must be the
default mode (or similarly named,
suggested mode for normal operation) as
defined by the manufacturer in its
product literature for giving selection
guidance to the consumer.
On September 17, 2018, DOE
published an RFI seeking information
on the emerging smart technology
appliance and equipment market. 83 FR
46886 (September 2018 RFI). In the
September 2018 RFI, DOE sought
information to better understand market
trends and issues in the emerging
market for appliances and commercial
equipment that incorporate smart
technology. Id. at 83 FR 46887. DOE’s
intent in issuing the September 2018
RFI was to ensure that DOE did not
inadvertently impede such innovation
when fulfilling its statutory obligations
to set efficiency standards for covered
products and equipment. Id. In the
April 2020 RFI, DOE sought comment
on the same issues presented in the
September 2018 RFI as they may be
specifically applicable to consumer
water heaters. 85 FR 21104, 21114
(April 16, 2020).
Responding to the April 2020 RFI,
commenters urged DOE to update the
test procedure to better capture the
performance differences between
traditional and connected products,
provided some recommended
definitions delineating the types of
connected products, and suggested that
DOE adopt additional and/or optional
performance metrics related to grid
connectivity. These comments are
discussed in detail in the January 2022
NOPR. 87 FR 1554, 1585 (Jan. 11, 2022).
In the January 2022 NOPR, DOE
proposed to explicitly state that any
connection to an external network or
control would be disconnected during
testing. DOE proposed this given that
there were insufficient data on
consumer usage of connected features
for the Department to develop a
representative test configuration for
assessing the energy consumption of
connected functionality for water
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heaters. 87 FR 1554, 1585–1586 (Jan. 11,
2022).
On this topic, BWC agreed with DOE’s
tentative determinations and
clarifications regarding the testing of
connected water heaters. (BWC, No. 33
at p. 9) NYSERDA recommended that
DOE ensure the test procedure supports
grid-enabled water heaters specifically,
as well as connected water heaters
generally. To this point, NYSERDA
recommended that DOE should specify
how manufacturers can demonstrate
their products are ‘‘connected’’ and
include this as an item for reporting to
the agency. NYSERDA encouraged DOE
to consider the power usage for
connectedness, as this would be
informative for utilities planning for
decarbonization. Additionally,
NYSERDA stated that including the
power usage for connected functions
would encourage the load to be minimal
and better inform consumers regarding
anticipated operating costs. (NYSERDA,
No. 32 at pp. 2–3)
In response, while DOE acknowledges
the potential benefits that could be
provided by connected capability, such
as providing energy saving benefits to
consumers and enabling peak load
shifting on the grid, the Department has
concluded that requiring measurement
and reporting of the energy consumed
by connected features at this time may
prematurely hinder the development
and incorporation of such features in
water heaters. As such, DOE is
clarifying that connected features on
water heaters should remain on but
disconnected from any external network
or control for the duration of the
appendix E test. This approach will
allow some baseline energy
consumption to be accounted for
without imposing any specific network
connection test requirements.
4. Heating Value of Gas
In this rulemaking, DOE considered
the need for a clarification regarding the
correction of the heating value to a
standard temperature and pressure.
Section 3.7 of appendix E states that the
heating values of natural gas and
propane must be corrected from those
reported at standard temperature and
pressure conditions to provide the
heating value at the temperature and
pressure measured at the fuel meter, but
does not specify standard temperature
and pressure conditions. Without a
specified standard temperature and
pressure, the heating values used in
calculations may not be consistent from
laboratory to laboratory.
As discussed in the January 2022
NOPR, there are several sources which
do specify the standard temperature and
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pressure conditions for natural gas
calculations. 87 FR 1554, 1578 (Jan. 11,
2022). For example, AHRI maintains an
Operations Manual for Residential
Water Heater Certification Program
(AHRI Operations Manual), which
includes an equation that corrects the
measured heating value, when using a
dry gas and a wet test meter, to the
heating value at the standard
temperature and pressure of 60 °F
(15.6 °C) and 30 inches of mercury
column (101.6 kPa), respectively. Annex
B of the March 2019 ASHRAE Draft
118.2 also provides a method for
correcting the heating value from
measured to standard conditions, which
allows for the use of either dry or
saturated gas and either a dry or wet test
meter—and this calculation was
finalized in ASHRAE 118.2–2022 with
an example provided for 60 °F (15.6 °C)
and 30 inches of mercury column (101.6
kPa). Lastly, sections 2.4.1 and 3.1.1 of
appendix O to subpart B of 10 CFR part
430 (Uniform Test Method for
Measuring the Energy Consumption of
Vented Home Heating Equipment)
correct the input rate to the standard
conditions of 60 °F (15.6 °C) and 30
inches of mercury column (101.6 kPa).
Therefore, to align with the AHRI
Operations Manual and the current
practice in other appendices within part
430 of the CFR, DOE proposed in the
January 2022 NOPR to establish the
standard temperature and pressure
conditions for gas measurements as
60 °F (15.6 °C) and 30 inches of mercury
column (101.6 kPa), respectively.
Further, DOE proposed to adopt the
method used in Annex B of a finalized
ASHRAE 118.2–2022 to correct the
heating value of gas to standard
conditions. 87 FR 1554, 1578 (Jan. 11,
2022).
DOE did not receive comments from
stakeholders regarding this proposal.
Accordingly, DOE is adopting these
proposals in this final rule for the
reasons previously discussed.
I. Effective and Compliance Dates
The effective date for the adopted test
procedure amendments will be 30 days
after publication of this final rule in the
Federal Register.
As to the compliance date, EPCA
prescribes that all representations of
energy efficiency and energy use for
consumer products (including consumer
water heaters),), including those made
on marketing materials and product
labels, must be made in accordance with
an amended test procedure, beginning
180 days after publication of the final
rule in the Federal Register. (42 U.S.C.
6293(c)(2)) For residential-duty
commercial water heaters, this
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requirement is beginning 360 days after
publication of the final rule in the
Federal Register. (42 U.S.C. 6314(d)(1))
For consumer products, EPCA provides
an allowance for individual
manufacturers to petition DOE for an
extension of the 180-day period if the
manufacturer may experience undue
hardship in meeting the deadline. (42
U.S.C. 6293(c)(3)) To receive such an
extension, petitions must be filed with
DOE no later than 60 days before the
end of the 180-day period and must
detail how the manufacturer will
experience undue hardship. (Id.)
With the exception of two test method
provisions (i.e., high temperature testing
and separate storage tank testing),
compliance with the modified test
procedure adopted in this final rule is
required for consumer water heaters
beginning 180 days after the date of
publication of this final rule in the
Federal Register. Similarly, with the
exception of the separate storage tank
testing requirement, compliance with
the modified test procedure is required
for residential-duty commercial water
heaters beginning 360 days after the
date of publication of this final rule in
the Federal Register.
Beginning on the effective date of this
final rule, the use of the high
temperature test method (section 5.1.2
of the amended appendix E test
procedure) will be allowed for voluntary
additional representations until the
compliance date of amended energy
conservation standards for consumer
water heaters that address high
temperature operation, should such
standards be adopted. Until such a time,
the normal temperature test method
(section 5.1.1 of the amended appendix
E test procedure) is required as the basis
for ratings used to determine
compliance with energy conservation
standards. During this voluntary usage
period, manufacturers who choose to
publish two sets of ratings must clearly
indicate which values correspond to the
high temperature test method. In the
standards rulemaking, DOE plans to
clarify which type(s) of water heaters
would be required to utilize the high
temperature test method when
determining compliance with potential
amended standards.
The use of the separate storage tank
test method for circulating water heaters
(section 4.10 of the amended appendix
E test procedure) will be allowed for
voluntary representations and
compliance with standards beginning
on the effective date of this final rule.
This test method will become
mandatory when compliance with
amended energy conservation standards
for consumer water heaters and
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residential-duty commercial water
heaters is required, should such
standards addressing circulating water
heaters be adopted.
Upon the compliance date of test
procedure provisions in this final rule,
any waivers that had been previously
issued and are in effect that pertain to
issues addressed by such provisions are
terminated. 10 CFR 430.27(h)(3) and
431.401(h)(3). Recipients of any such
waivers are required to test the products
subject to the waiver according to the
amended test procedure as of the
compliance date of the amended test
procedure. The amendments adopted in
this document pertain to issues
addressed by a waiver granted to
Bradford White Corporation (Case No.
2019–006). See 85 FR 5648 (Jan. 31,
2020). On January 31, 2020, DOE
published a Notice of Decision and
Order in the Federal Register granting
Bradford White Corporation a waiver for
a specified basic model that experiences
the first cut-out of the 24-hour
simulated-use test during a draw. 85 FR
5648. The Decision and Order requires
Bradford White Corporation to use an
alternate test procedure that DOE
determined more accurately calculates
the recovery efficiency when the first
cut-out occurs during a draw. Id. at 85
FR 5651. As described in section
III.B.2.b of this document, DOE is
adopting the alternate test procedure
prescribed in the Decision and Order
granted to Bradford White Corporation
into the test procedure at appendix E.
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J. Test Procedure Costs
EPCA requires that test procedures
proposed by DOE not be unduly
burdensome to conduct. (42 U.S.C.
6293(b)(3)) The following sections
discuss DOE’s evaluation of estimated
costs associated with the proposed
amendments for consumer water heaters
and residential-duty commercial water
heaters.
1. Separate Storage Tanks
In the January 2022 NOPR, DOE
tentatively concluded that the cost of
running the test procedure using an 80gallon unfired hot water storage tank
should be the same as testing a water
heater with an integrated tank with a
comparable storage volume. The
Department estimated that testing a
fossil fuel-fired or electric storage water
heater would cost approximately $3,000
and that testing an electric storage water
heater which uses heat pump
technology would cost approximately
$4,500. In addition to the testing cost,
the manufacturer or third-party testing
facility would incur a one-time cost to
purchase an unfired hot water storage
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tank which are commercially available
for approximately $900. 87 FR 1554,
1589 (Jan. 11, 2022).
In the July 2022 SNOPR, DOE revised
its proposal. DOE estimated that, for
gas-fired circulating water heaters, these
proposed changes could require a onetime purchase of an 80- to 120-gallon
unfired hot water storage tank, which
are readily commercially available for
approximately $2,000. For heat pumponly water heaters, the proposed
changes could result in a one-time
purchase of a 40-gallon (±4 gallons)
electric storage water heater readily
available for approximately $500. 87 FR
42270, 42283 (July 14, 2022).
DOE evaluated stakeholder feedback
regarding this testing requirement and
further revised its amended provision.
This final rule adopts the following
changes concerning the testing of
circulating water heaters:
(1) Gas-fired circulating water heaters
be tested using an unfired hot water
storage tank with a storage volume
between 80 and 120 gallons and an Rvalue exactly at the minimum R-value
required at 10 CFR 431.110(a).
(2) Heat pump circulating water
heaters be tested using a 40-gallon (±5
gallons) electric storage water heater at
the minimum UEF standard required at
10 CFR 430.32(d).
AHRI generally agreed with the
estimated costs presented in the January
2022 NOPR, with the exception that
$900 may be an underestimate of the
cost of purchasing an unfired hot water
storage tank. (AHRI, No. 40 at p. 3) No
further comments on test costs were
received in response to the July 2022
SNOPR. Based upon its subsequent
review in light of AHRI’s comment, DOE
notes that its estimate for the retail price
of an unfired hot water storage tank has
been raised from $900 to $2,000.
In response, DOE recognizes that
these amendments will require
manufacturers to make one-time
purchases of the necessary storage tanks
for each testing facility. DOE’s research
indicates that the tanks required for
testing gas-fired circulating water
heaters and heat pump circulating water
heaters are commercially available at
retail prices of $2,000 and $500,
respectively, thereby reflecting thirdparty laboratory testing costs.
These amendments to appendix E
regarding storage tank requirements will
allow affected models to be certified for
the first time. Manufacturers will not be
able to rely on data generated under test
procedures in effect prior to this final
rule.
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2. Method for Determining Internal
Tank Temperature for Certain Water
Heaters
This final rule amends section 5.4 of
appendix E by the addition of section
5.4.2.2, which allows internal tank
temperature to be estimated by
removing water from the water heater
for models with rated storage volumes
greater than or equal to 2 gallons whose
internal tank temperatures are unable to
be measured using thermocouples.
DOE estimates that this testing
method may extend test duration by up
to 8 hours as part of the final standby
period of the 24-hour simulated use test.
This additional duration is estimated to
increase testing costs by up to $1,000 for
affected fossil-fuel-fired and electric
water heaters and $1,500 for affected
heat pump water heaters.
The addition of section 5.4.2.2 to
appendix E will allow affected models
to be certified for the first time. Because
these water heaters could not previously
be accurately tested, manufacturers will
not be able to rely on data generated
under test procedures in effect prior to
this final rule.
3. High Temperature Testing
DOE recognizes that the amendment
specifying the high temperature testing
method would likely cause UEF ratings
for any products that would become
subject to this test method (i.e., a subset
of electric resistance storage water
heaters) to decrease if they are currently
certified using a default temperature
setting. In order to limit potential
retesting and recertification burden for
manufacturers, any requirement to test
certain products using the high
temperature testing method will be
established only once DOE completes its
ongoing reviews of potential amended
energy conservation standards for
consumer water heaters, should such
standards be adopted. The cost to test
per this amended method would not be
different from the cost to test per the
method in the currently applicable
appendix E test procedure (i.e., testing
an electric storage water heater would
cost approximately $3,000).
4. Additional Amendments
The remainder of the test procedure
amendments adopted in this final rule
will not impact test costs.
DOE is amending section 2.5 of
appendix E, ‘‘Set Point Temperature,’’ to
allow low-temperature water heaters to
deliver water at the maximum outlet
temperature that they are capable of
producing. This aligns with how these
products are tested currently.
Manufacturers already should have
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requested a waiver for these products, as
the current test procedure cannot be
used as written to test low-temperature
water heaters. As these products are
currently tested and rated to the
procedures which DOE is adopting,
there should be no additional cost
associated with this change.
DOE is also amending the existing test
procedure for consumer and residentialduty commercial water heaters by
modifying the flow rate requirements
during the FHR test for water heaters
with a rated storage volume less than 20
gallons. This change does not
significantly affect the test results of the
FHR test, and, thus, DOE expects that
manufacturers may rely on existing test
data where available. Further, storagetype water heaters (which comprise the
majority of water heaters that need to be
tested for an FHR rating) with less than
20 gallons of rated storage volume
currently do not have energy
conservation standards codified at 10
CFR 430.32(d) and are, therefore, not
rated and certified to DOE.
Instantaneous-type water heaters that
will require an FHR rating are expected
to be circulating water heaters, and this
final rule amends the appendix E test
procedure in such a way that allows
these products to be tested and rated for
the first time (test costs for water heaters
requiring separate storage tanks are
discussed in section III.J.1 of this
document). Therefore, the update to the
FHR test method does not change the
expected testing costs for products
which have been tested per appendix E
previously.
DOE is also amending the timing of
the first measurement in each draw of
the 24-hour simulated-use test and the
test condition specifications and
tolerances, including electric supply
voltage tolerance, ambient temperature,
ambient dry-bulb temperature, ambient
relative humidity, standard temperature
and pressure definition, gas supply
pressure, and manifold pressure. These
changes are intended to reduce retesting
associated with having a single
measurement out of tolerance, while
maintaining the current
representativeness of the test conditions
and the stringency of the tolerances for
the test conditions. DOE also has
determined that the amendment to the
flow rate tolerances for water heaters
less than 2 gallons in rated storage
volume would not alter the measured
efficiency of consumer water heaters
and residential-duty commercial water
heaters, nor require retesting or
recertification. In the absence of an
explicit instruction for the flow rate
tolerance applicable to water heaters
with rated storage volume under 2
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gallons, DOE expects that general
industry best practice is to apply the
flow rate tolerances being adopted for
section 5.4.3 of appendix E for water
heaters with rated storage volume less
than 2 gallons (based on DOE’s review
of third-party laboratory test data), such
that this proposal is expected to be
consistent with current methodology.
Manufacturers will be able to rely on
data generated under the current water
heaters test procedure for the remainder
of the amendments set forth in this final
rule, so accordingly, such changes
should result in no associated increase
in costs.
techniques may include identifying
changing future compliance costs that
might result from technological
innovation or anticipated behavioral
changes. For the reasons stated in the
preamble, this final regulatory action is
consistent with these principles.
Section 6(a) of E.O. 12866 also
requires agencies to submit ‘‘significant
regulatory actions’’ to OIRA for review.
OIRA has determined that this final
regulatory action does not constitute a
‘‘significant regulatory action’’ under
section 3(f) of E.O. 12866. Accordingly,
this action was not submitted to OIRA
for review under E.O. 12866.
IV. Procedural Issues and Regulatory
Review
B. Review Under the Regulatory
Flexibility Act
The Regulatory Flexibility Act (5
U.S.C. 601 et seq.) requires preparation
of a final regulatory flexibility analysis
(FRFA) for any final rule where the
agency was first required by law to
publish a proposed rule for public
comment, unless the agency certifies
that the rule, if promulgated, will not
have a significant economic impact on
a substantial number of small entities.
As required by Executive Order 13272,
‘‘Proper Consideration of Small Entities
in Agency Rulemaking,’’ 67 FR 53461
(August 16, 2002), DOE published
procedures and policies on February 19,
2003 to ensure that the potential
impacts of its rules on small entities are
properly considered during the DOE
rulemaking process. 68 FR 7990. DOE
has made its procedures and policies
available on the Office of the General
Counsel’s website: www.energy.gov/gc/
office-general-counsel. DOE reviewed
this final rule under the provisions of
the Regulatory Flexibility Act and the
procedures and policies published on
February 19, 2003.
DOE is amending test procedures for
consumer water heaters and residentialduty commercial water heaters. DOE is
publishing this final rule in satisfaction
of the 7-year-lookback review
requirement specified in EPCA. (42
U.S.C. 6293(b)(1)(A); 6314(a)(1))
Further, amending test procedures for
consumer and residential-duty
commercial water heaters assists DOE in
fulfilling its statutory deadline for
amending energy conservation
standards for products and equipment
that achieve the maximum improvement
in energy efficiency that is
technologically feasible and
economically justified. (42 U.S.C.
6295(o)(2)(A); 42 U.S.C. 6313(a)(6))
Additionally, amending test procedures
for consumer and residential-duty
commercial water heaters allows
manufacturers to produce
measurements of energy efficiency that
A. Review Under Executive Orders
12866, 13563, and 14094
Executive Order (E.O.) 12866,
‘‘Regulatory Planning and Review,’’ 58
FR 51735 (Oct. 4, 1993), as
supplemented and reaffirmed by E.O.
13563, ‘‘Improving Regulation and
Regulatory Review,’’ 76 FR 3821 (Jan.
21, 2011) and E.O. 14094, ‘‘Modernizing
Regulatory Review,’’ 88 FR 21879 (April
11, 2023), requires agencies, to the
extent permitted by law, to: (1) propose
or adopt a regulation only upon a
reasoned determination that its benefits
justify its costs (recognizing that some
benefits and costs are difficult to
quantify); (2) tailor regulations to
impose the least burden on society,
consistent with obtaining regulatory
objectives, taking into account, among
other things, and to the extent
practicable, the costs of cumulative
regulations; (3) select, in choosing
among alternative regulatory
approaches, those approaches that
maximize net benefits (including
potential economic, environmental,
public health and safety, and other
advantages; distributive impacts; and
equity); (4) to the extent feasible, specify
performance objectives, rather than
specifying the behavior or manner of
compliance that regulated entities must
adopt; and (5) identify and assess
available alternatives to direct
regulation, including providing
economic incentives to encourage the
desired behavior, such as user fees or
marketable permits, or providing
information upon which choices can be
made by the public. DOE emphasizes as
well that E.O. 13563 requires agencies to
use the best available techniques to
quantify anticipated present and future
benefits and costs as accurately as
possible. In its guidance, the Office of
Information and Regulatory Affairs
(OIRA) in the Office of Management and
Budget (OMB) has emphasized that such
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are representative of an average use
cycle and uniform for all manufacturers.
On January 11, 2022, DOE published
a test procedure NOPR (January 2022
NOPR) in the Federal Register
proposing to amend the test procedure
for consumer water heaters and
residential-duty commercial gas water
heaters. See 87 FR 1554. DOE published
a supplemental test procedure NOPR on
July 14, 2022 (July 2022 SNOPR) in the
Federal Register, proposing certain
modifications to the January 2022
NOPR. See 87 FR 42270.
DOE conducted an initial regulatory
flexibility analysis (IRFA) as part of the
January 2022 NOPR and July 2022
SNOPR. See 87 FR 1554, 1590–1592
(Jan. 11, 2022); 87 FR 42270, 42285–
42287 (July 14, 2022). The following
sections outline DOE’s determination
that this final rule does not have a
‘‘significant economic impact on a
substantial number of small entities,’’
and that the preparation of a FRFA is
not warranted. DOE did not receive
comment specific to the impacts on
small business manufacturers as part of
the above-referenced IRFAs.
For manufacturers of consumer water
heaters and residential-duty commercial
water heaters, the Small Business
Administration (SBA) has set a size
threshold, which defines those entities
classified as ‘‘small businesses’’ for the
purposes of the statute. DOE used the
SBA’s small business size standards to
determine whether any small entities
would be subject to the requirements of
the rule. (See 13 CFR part 121.) The size
standards are listed by North American
Industry Classification System (NAICS)
code and industry description and are
available at: www.sba.gov/document/
support—table-size-standards.
Manufacturing of consumer water
heaters and residential-duty commercial
water heaters is classified under NAICS
335220, ‘‘Major Household Appliance
Manufacturing.’’ The SBA sets a
threshold of 1,500 employees or fewer
for an entity to be considered as a small
business for this category. DOE used
available public information to identify
potential small manufacturers. DOE
accessed CCMS,79 the certified product
directory of the AHRI,80 company
websites, and manufacturer literature to
identify companies that import, private
label, or produce the consumer water
heaters and residential-duty commercial
water heaters covered by this
79 U.S. Department of Energy Compliance
Certification Management System, available at:
www.regulations.doe.gov/ccms. (Last accessed July
19, 2022).
80 AHRI Directory of Certified Product
Performance is available at: www.ahridirectory.org/
Search/SearchHome (Last accessed July 19, 2022).
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rulemaking. Using these sources, DOE
has identified a total of 27
manufacturers of consumer water
heaters and residential-duty commercial
water heaters.81 Of these 27
manufacturers, DOE identified one
domestic small business that
manufactures products covered by the
test procedure amendments.
More specifically, in the January 2022
NOPR IRFA, DOE evaluated a range of
potential test procedure amendments,
with one amendment that could lead to
additional testing costs for small
business. The existing DOE test
procedure does not accommodate
testing of circulating water heaters that
require a separately sold hot water
storage tank to properly operate. In the
January 2022 NOPR, DOE proposed to
add procedures to test such circulating
water heaters to improve the
representativeness of the test procedure.
The January 2022 NOPR proposed
testing be based on a commonly
available 80-gallon unfired hot water
storage tank which minimally meets the
energy conservation standard
requirements at 10 CFR 431.110(a). DOE
estimated that the cost of running the
amended test procedure should be the
same as testing a comparable water
heater with storage volume (i.e., thirdparty testing of a fossil fuel-fired or
electric storage water heater would cost
approximately $3,000; third-party
testing of an electric storage water
heater which uses heat pump
technology would cost approximately
$4,500). If a manufacturer chose to
perform in-house testing rather than use
a third-party, the unfired hot water
storage tank was stated to be
commercially available for
approximately $900. The January 2022
IRFA identified one small manufacturer
and estimated compliance costs to be
$4,500. 87 FR 1554, 1591 (Jan. 11, 2022).
The July 2022 SNOPR further updated
DOE’s proposal for testing circulating
water heaters that require a separatelysold hot water storage tank to properly
operate. Specifically, the July 2022
SNOPR differentiated the test
requirements for gas-fired circulating
water heaters and heat pump circulating
water heaters. The July 2022 SNOPR
proposed that heat pump circulating
water heaters be tested using an electric
storage water heaters that have a rated
storage volume of 40 gallons ± 4 gallons,
have an FHR that results in
classification at the medium draw
81 The January 2022 NOPR identified 31
manufacturers. 87 FR 1554, 1591 (Jan. 11, 2022).
The July 2022 SNOPR identified 27 manufacturers.
The changes reflect revisions based on
manufacturer feedback and additional public
information.
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pattern, and be rated at exactly the
minimum required UEF. Compared to
the January 2022 NOPR, DOE revised
the requirements for circulating heat
pump water heaters to better reflect how
heat pump water heaters may be
installed in the field. To determine cost
of testing, DOE utilized a third-party test
estimate of $4,500. The July 2022 IRFA
identified one small manufacturer and
estimated compliance costs to be
$4,500. The proposal for heat pump
circulating water heaters was the only
amendment in the July 2022 SNOPR
that could cause the small manufacturer
to incur additional costs. 87 FR 42270,
42286–42287 (July 14, 2022).
In this final rule, DOE is establishing
testing requirements consistent with the
proposal for heat pump circulating
water heaters in the July 2022 SNOPR,
except that the acceptable volume range
for the separate tank has been expanded
to 40 gallons ± 5 gallons. For this final
rule, DOE is aware of one domestic
small manufacturer. The small
manufacturers has a single model (a
circulating heat pump water heater that
requires a separately-sold hot water
tank) that would be affected by the
amendments being adopted and that
would need to be re-tested. DOE
estimates that testing would cost $4,500.
If the manufacturer conducts two
rounds of physical testing, DOE expects
the cost impact on the small
manufacturer to be $9,000, which is less
than 0.01% of company revenue.
DOE has determined the cost impact
to small businesses as result of the
amendments in this final rule to be
minimal. DOE did not receive any
comments specifically pertaining to
small business impacts. Therefore, on
the basis of the de minimis compliance
burden, DOE certifies that this test
procedure final rule does not have a
‘‘significant economic impact on a
substantial number of small entities,’’
and that the preparation of a FRFA is
not warranted. DOE has submitted a
certification and supporting statement
of factual basis to the Chief Counsel for
Advocacy of the Small Business
Administration for review under 5
U.S.C. 605(b).
C. Review Under the Paperwork
Reduction Act of 1995
Manufacturers of consumer water
heaters and manufacturers of
residential-duty commercial water
heaters must certify to DOE that their
products comply with any applicable
energy conservation standards. To
certify compliance, manufacturers must
first obtain test data for their products
according to the DOE test procedures,
including any amendments adopted for
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those test procedures. DOE has
established regulations for the
certification and recordkeeping
requirements for all covered consumer
products and commercial equipment,
including consumer water heaters and
residential-duty commercial water
heaters. (See generally 10 CFR part 429.)
The collection-of-information
requirement for the certification and
recordkeeping is subject to review and
approval by OMB under the Paperwork
Reduction Act (PRA). This requirement
has been approved by OMB under OMB
control number 1910–1400. Public
reporting burden for the certification is
estimated to average 35 hours per
response, including the time for
reviewing instructions, searching
existing data sources, gathering and
maintaining the data needed, and
completing and reviewing the collection
of information.
DOE is not amending the certification
or reporting requirements for consumer
water heaters and residential-duty
commercial water heaters in this final
rule. Instead, DOE may consider
proposals to amend the certification
requirements and reporting for these
products and equipment under a
separate rulemaking regarding appliance
and equipment certification. DOE will
address changes to OMB Control
Number 1910–1400 at that time, as
necessary.
Notwithstanding any other provision
of the law, no person is required to
respond to, nor shall any person be
subject to a penalty for failure to comply
with, a collection of information subject
to the requirements of the PRA, unless
that collection of information displays a
currently valid OMB Control Number.
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D. Review Under the National
Environmental Policy Act of 1969
In this final rule, DOE amends the test
procedure for consumer water heaters
and residential-duty commercial water
heaters, amendments which it expects
will be used to develop and implement
future energy conservation standards for
such products and equipment. DOE has
determined that this rule falls into a
class of actions that are categorically
excluded from review under the
National Environmental Policy Act of
1969 (42 U.S.C. 4321 et seq.) and DOE’s
implementing regulations at 10 CFR part
1021. Specifically, DOE has determined
that adopting test procedures for
measuring energy efficiency of
consumer products and industrial
equipment is consistent with activities
identified in 10 CFR part 1021, subpart
D, appendix A, sections A5 and A6.
Accordingly, neither an environmental
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assessment nor an environmental
impact statement is required.
E. Review Under Executive Order 13132
Executive Order 13132, ‘‘Federalism,’’
64 FR 43255 (August 1010, 1999),
imposes certain requirements on
agencies formulating and implementing
policies or regulations that preempt
State law or that have federalism
implications. The Executive order
requires agencies to examine the
constitutional and statutory authority
supporting any action that would limit
the policymaking discretion of the
States and to carefully assess the
necessity for such actions. The
Executive order also requires agencies to
have an accountable process to ensure
meaningful and timely input by State
and local officials in the development of
regulatory policies that have federalism
implications. On March 14, 2000, DOE
published a statement of policy
describing the intergovernmental
consultation process it will follow in the
development of such regulations. 65 FR
13735. DOE examined this final rule
and determined that it will not have a
substantial direct effect on the States, on
the relationship between the national
government and the States, or on the
distribution of power and
responsibilities among the various
levels of government. EPCA governs and
prescribes Federal preemption of State
regulations as to energy conservation for
the products and equipment that are the
subject of this final rule. States can
petition DOE for exemption from such
preemption to the extent, and based on
criteria, set forth in EPCA. (42 U.S.C.
6297(d)) No further action is required by
Executive Order 13132.
F. Review Under Executive Order 12988
Regarding the review of existing
regulations and the promulgation of
new regulations, section 3(a) of
Executive Order 12988, ‘‘Civil Justice
Reform,’’ 61 FR 4729 (Feb. 7, 1996),
imposes on Federal agencies the general
duty to adhere to the following
requirements: (1) eliminate drafting
errors and ambiguity; (2) write
regulations to minimize litigation; (3)
provide a clear legal standard for
affected conduct rather than a general
standard; and (4) promote simplification
and burden reduction. Section 3(b) of
Executive Order 12988 specifically
requires that Executive agencies make
every reasonable effort to ensure that the
regulation: (1) clearly specifies the
preemptive effect, if any; (2) clearly
specifies any effect on existing Federal
law or regulation; (3) provides a clear
legal standard for affected conduct
while promoting simplification and
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burden reduction; (4) specifies the
retroactive effect, if any; (5) adequately
defines key terms; and (6) addresses
other important issues affecting clarity
and general draftsmanship under any
guidelines issued by the Attorney
General. Section 3(c) of Executive Order
12988 requires executive agencies to
review regulations in light of applicable
standards in sections 3(a) and 3(b) to
determine whether they are met or it is
unreasonable to meet one or more of
them. DOE has completed the required
review and determined that, to the
extent permitted by law, this final rule
meets the relevant standards of
Executive Order 12988.
G. Review Under the Unfunded
Mandates Reform Act of 1995
Title II of the Unfunded Mandates
Reform Act of 1995 (UMRA) requires
each Federal agency to assess the effects
of Federal regulatory actions on State,
local, and Tribal governments and the
private sector. Public Law 104–4, sec.
201 (codified at 2 U.S.C. 1531). For a
regulatory action resulting in a rule that
may cause the expenditure by State,
local, and Tribal governments, in the
aggregate, or by the private sector of
$100 million or more in any one year
(adjusted annually for inflation), section
202 of UMRA requires a Federal agency
to publish a written statement that
estimates the resulting costs, benefits,
and other effects on the national
economy. (2 U.S.C. 1532(a), (b)) The
UMRA also requires a Federal agency to
develop an effective process to permit
timely input by elected officers of State,
local, and Tribal governments on a
proposed ‘‘significant intergovernmental
mandate,’’ and requires an agency plan
for giving notice and opportunity for
timely input to potentially affected
small governments before establishing
any requirements that might
significantly or uniquely affect small
governments. On March 18, 1997, DOE
published a statement of policy on its
process for intergovernmental
consultation under UMRA. 62 FR
12820; also available at
www.energy.gov/gc/office-generalcounsel. DOE examined this final rule
according to UMRA and its statement of
policy and determined that the rule
contains neither an intergovernmental
mandate, nor a mandate that may result
in the expenditure of $100 million or
more in any year, so these requirements
do not apply.
H. Review Under the Treasury and
General Government Appropriations
Act, 1999
Section 654 of the Treasury and
General Government Appropriations
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Federal Register / Vol. 88, No. 118 / Wednesday, June 21, 2023 / Rules and Regulations
Act, 1999 (Pub. L. 105–277) requires
Federal agencies to issue a Family
Policymaking Assessment for any rule
that may affect family well-being. This
final rule will not have any impact on
the autonomy or integrity of the family
as an institution. Accordingly, DOE has
concluded that it is not necessary to
prepare a Family Policymaking
Assessment.
I. Review Under Executive Order 12630
DOE has determined, under Executive
Order 12630, ‘‘Governmental Actions
and Interference with Constitutionally
Protected Property Rights,’’ 53 FR 8859
(March 18, 1988), that this regulation
will not result in any takings that might
require compensation under the Fifth
Amendment to the U.S. Constitution.
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J. Review Under Treasury and General
Government Appropriations Act, 2001
Section 515 of the Treasury and
General Government Appropriations
Act, 2001 (44 U.S.C. 3516 note) provides
for agencies to review most
disseminations of information to the
public under guidelines established by
each agency pursuant to general
guidelines issued by OMB. OMB’s
guidelines were published at 67 FR
8452 (Feb. 22, 2002), and DOE’s
guidelines were published at 67 FR
62446 (Oct. 7, 2002). Pursuant to OMB
Memorandum M–19–15, Improving
Implementation of the Information
Quality Act (April 24, 2019), DOE
published updated guidelines which are
available at: www.energy.gov/sites/prod/
files/2019/12/f70/DOE
%20Final%20Updated%20IQA
%20Guidelines%20Dec%202019.pdf.
DOE has reviewed this final rule under
the OMB and DOE guidelines and has
concluded that it is consistent with
applicable policies in those guidelines.
K. Review Under Executive Order 13211
Executive Order 13211, ‘‘Actions
Concerning Regulations That
Significantly Affect Energy Supply,
Distribution, or Use,’’ 66 FR 28355 (May
22, 2001), requires Federal agencies to
prepare and submit to OMB, a
Statement of Energy Effects for any
significant energy action. A ‘‘significant
energy action’’ is defined as any action
by an agency that promulgated or is
expected to lead to promulgation of a
final rule, and that: (1) is a significant
regulatory action under Executive Order
12866, or any successor order; and (2)
is likely to have a significant adverse
effect on the supply, distribution, or use
of energy; or (3) is designated by the
Administrator of OIRA as a significant
energy action. For any significant energy
action, the agency must give a detailed
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19:48 Jun 20, 2023
Jkt 259001
statement of any adverse effects on
energy supply, distribution, or use if the
regulation is implemented, and of
reasonable alternatives to the action and
their expected benefits on energy
supply, distribution, and use.
This regulatory action is not a
significant regulatory action under
Executive Order 12866. Moreover, it
would not have a significant adverse
effect on the supply, distribution, or use
of energy, nor has it been designated as
a significant energy action by the
Administrator of OIRA. Therefore, it is
not a significant energy action, and,
accordingly, DOE has not prepared a
Statement of Energy Effects.
L. Review Under Section 32 of the
Federal Energy Administration Act of
1974
Under section 301 of the Department
of Energy Organization Act (Pub. L. 95–
91; 42 U.S.C. 7101), DOE must comply
with section 32 of the Federal Energy
Administration Act of 1974, as amended
by the Federal Energy Administration
Authorization Act of 1977. (15 U.S.C.
788; ‘‘FEAA’’) Section 32 essentially
provides in relevant part that, where a
proposed rule authorizes or requires use
of commercial standards, the notice of
proposed rulemaking must inform the
public of the use and background of
such standards. In addition, section
32(c) requires DOE to consult with the
Attorney General and the Chairman of
the Federal Trade Commission (FTC)
concerning the impact of the
commercial or industry standards on
competition.
The modifications to the Federal test
procedure for consumer water heaters
and residential-duty commercial water
heaters adopted in this final rule
incorporate testing methods contained
in certain sections of the following
applicable commercial test standards:
ASHRAE 41.1–2020, ASTM D2156–09
(RA 2018), and ASHRAE 118.2–2022.
DOE has evaluated these standards and
is unable to conclude whether they fully
comply with the requirements of section
32(b) of the FEAA (i.e., whether it was
developed in a manner that fully
provides for public participation,
comment, and review.) DOE has
consulted with both the Attorney
General and the Chairman of the FTC
about the impact on competition of
using the methods contained in these
standards and has received no
comments objecting to their use.
M. Congressional Notification
As required by 5 U.S.C. 801, DOE will
report to Congress on the promulgation
of this rule before its effective date. The
report will state that it has been
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40471
determined that the final rule is not a
‘‘major rule’’ as defined by 5 U.S.C.
804(2).
N. Description of Materials Incorporated
by Reference
In this final rule, DOE incorporates by
reference the following test standards:
ASHRAE 41.1–2020 prescribes
methods for measuring temperature
under laboratory and field conditions
which are required for system
performance tests and for testing
heating, ventilating, air-conditioning,
and refrigerating components.
ASHRAE 41.6–2014 prescribes
methods for measuring the humidity of
moist air with instruments.
ASHRAE 118.2–2022 provides test
procedures for rating the efficiency and
hot water delivery capabilities of
directly heated residential water heaters
and residential-duty commercial water
heaters.
ASTM D2156–09 (RA 2018) provides
a test method to evaluate the density of
smoke in the flue gases from burning
distillate fuels, which is intended
primarily for use with home heating
equipment burning kerosene or heating
oils, and can be used in the laboratory
or in the field to compare fuels for clean
burning or to compare heating
equipment.
ASTM E97–1987 (W1991) provides a
method to determine the 45-deg, 0-deg
directional reflectance factor of
nonfluorescent opaque specimens by
means of filter photometers.
Copies of ASHRAE 41.1–2020,
ASHRAE 41.6–2014, and ASHRAE
118.2–2022 are reasonably available
from the American Society of Heating,
Refrigerating, and Air-Conditioning
Engineers, Inc., 180 Technology
Parkway NW, Peachtree Corners, GA
30092, (800) 527–4723 or (404) 636–
8400, or online at: www.ashrae.org.
Copies of ASTM D2156–09 (RA 2018)
are reasonably available from ASTM
International, 100 Barr Harbor Drive,
P.O. Box C700, West Conshohocken, PA
19428–2959 or online at: www.astm.org.
Copies of ASTM E97–1987 (W1991)
are reasonably available from standards
resellers including GlobalSpec’s
Engineering 360 (https://
standards.globalspec.com/std/3801495/
astm-e97-82-1987) and IHS Markit
(https://global.ihs.com/doc_
detail.cfm?document_
name=ASTM%20E97&item_s_
key=00020483).
V. Approval of the Office of the
Secretary
The Secretary of Energy has approved
publication of this final rule.
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List of Subjects
10 CFR Part 429
Administrative practice and
procedure, Confidential business
information, Energy conservation,
Household appliances, Imports,
Intergovernmental relations, Reporting
and recordkeeping requirements, Small
businesses.
Administrative practice and
procedure, Confidential business
information, Energy conservation,
Household appliances, Imports,
Incorporation by reference,
Intergovernmental relations, Reporting
and recordkeeping requirements, Small
businesses.
10 CFR Part 431
Administrative practice and
procedure, Confidential business
information, Energy conservation,
Household appliances, Imports,
Intergovernmental relations,
Laboratories, Reporting and
recordkeeping requirements, Small
businesses.
Signing Authority
This document of the Department of
Energy was signed on May 22, 2023, by
Francisco Alejandro Moreno, Acting
Assistant Secretary for Energy Efficiency
and Renewable Energy, pursuant to
delegated authority from the Secretary
of Energy. That document with the
original signature and date is
maintained by DOE. For administrative
purposes only, and in compliance with
requirements of the Office of the Federal
Register, the undersigned DOE Federal
Register Liaison Officer has been
authorized to sign and submit the
document in electronic format for
publication, as an official document of
the Department of Energy. This
administrative process in no way alters
the legal effect of this document upon
publication in the Federal Register.
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Signed in Washington, DC, on May 24,
2023.
Treena V. Garrett,
Federal Register Liaison Officer, U.S.
Department of Energy.
For the reasons stated in the
preamble, DOE amends parts 429, 430,
and 431 of Chapter II of Title 10, Code
of Federal Regulations, as set forth
below:
19:48 Jun 20, 2023
1. The authority citation for part 429
continues to read as follows:
■
Authority: 42 U.S.C. 6291–6317; 28 U.S.C.
2461 note.
2. Amend § 429.70 by revising
paragraph (g)(2) and adding paragraph
(g)(3) to read as follows:
■
10 CFR Part 430
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PART 429—CERTIFICATION,
COMPLIANCE, AND ENFORCEMENT
FOR CONSUMER PRODUCTS AND
COMMERCIAL AND INDUSTRIAL
EQUIPMENT
Jkt 259001
§ 429.70 Alternative methods for
determining energy efficiency and energy
use.
*
*
*
*
*
(g) * * *
(2) Electric Storage Water Heaters.
Rate an untested basic model of an
electric storage-type water heater using
the first-hour rating or maximum GPM
(whichever is applicable under section
5.3.1 of appendix E to subpart B of this
part) and uniform energy factor obtained
from a tested basic model as the basis
for ratings of basic models with other
input ratings, provided that certain
conditions are met:
(i) For an untested basic model, the
represented value of the first-hour rating
or maximum GPM and the uniform
energy factor is the same as that of a
tested basic model, provided that each
heating element of the untested basic
model is rated at or above the input
rating for the corresponding heating
element of the tested basic model.
(ii) For an untested basic model
having any heating element with an
input rating that is lower than that of
the corresponding heating element in
the tested basic model, the represented
value of the first-hour rating or
maximum GPM and the uniform energy
factor is the same as that of a tested
basic model, provided that the first-hour
rating for the untested basic model
results in the same draw pattern
specified in Table I of appendix E for
the simulated-use test as was applied to
the tested basic model. To establish
whether this condition is met,
determine the first-hour ratings or
maximum GPMs for the tested and the
untested basic models in accordance
with the procedure described in section
5.3 of 10 CFR part 430, subpart B,
appendix E, then compare the
appropriate draw pattern specified in
Table I of appendix E for the first-hour
rating of the tested basic model with
that for the untested basic model. If this
condition is not met, then the untested
basic model must be tested, and the
appropriate sampling provisions must
be applied to determine its uniform
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energy factor in accordance with
appendix E and this part.
(3) Electric Instantaneous Water
Heaters. Rate an untested basic model of
an electric instantaneous-type water
heater using the first-hour rating or
maximum GPM and the uniform energy
factor obtained from a tested basic
model as a basis for ratings of basic
models with other input ratings,
provided that certain conditions are
met:
(i) For an untested basic model, the
represented value of the first-hour rating
or maximum GPM and the uniform
energy factor is the same as that of a
tested basic model, provided that the
untested basic model’s input is rated at
or above the input rating for the
corresponding tested basic model.
(ii) For an untested basic model
having an input rating that is lower than
that of the corresponding tested basic
model, the represented value of the firsthour rating or maximum GPM and the
uniform energy factor is the same as that
of a tested basic model, provided that
the first-hour rating or maximum GPM
for the untested basic model results in
the same draw pattern specified in
Table II of appendix E for the 24-hour
simulated-use test as was applied to the
tested basic model. To establish whether
this condition is met, determine the
first-hour rating or maximum GPM for
the tested and the untested basic models
in accordance with the procedure
described in section 5.3 of 10 CFR part
430, subpart B, appendix E, then
compare the appropriate draw pattern
specified in Table II of appendix E for
the first-hour rating or maximum GPM
of the tested basic model with that for
the untested basic model. If this
condition is not met, then the untested
basic model must be tested, and the
appropriate sampling provisions must
be applied to determine its uniform
energy factor in accordance with
appendix E and this part.
*
*
*
*
*
■ 3. Amend § 429.134 by adding
paragraph (d)(3) to read as follows:
§ 429.134 Product-specific enforcement
provisions.
*
*
*
*
*
(d) * * *
(3) Verification of fuel input rate. The
fuel input rate of each tested unit of the
basic model will be measured pursuant
to the test requirements of section 5.2.3
of 10 CFR part 430, subpart B, appendix
E. The measured fuel input rate (either
the measured fuel input rate for a single
unit sample or the average of the
measured fuel input rates for a multiple
unit sample) will be compared to the
rated input certified by the
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manufacturer. The certified rated input
will be considered valid only if the
measured fuel input rate is within ±2
percent of the certified rated input.
(i) If the certified rated input is found
to be valid, then the certified rated input
will be used to determine compliance
with the associated energy conservation
standard.
(ii) If the measured fuel input rate for
gas-fired or oil-fired water heating
products is not within ±2 percent of the
certified rated input, the measured fuel
input rate will be used to determine
compliance with the associated energy
conservation standard.
*
*
*
*
*
PART 430—ENERGY CONSERVATION
PROGRAM FOR CONSUMER
PRODUCTS
4. The authority citation for part 430
continues to read as follows:
■
Authority: 42 U.S.C. 6291–6309; 28 U.S.C.
2461 note.
§ 430.3 Materials incorporated by
reference.
5. Amend § 430.2 by adding in
alphabetical order definitions for
‘‘Circulating water heater’’, ‘‘Lowtemperature water heater’’, and
‘‘Tabletop water heater’’ to read as
follows:
■
§ 430.2
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*
Definitions.
*
*
*
*
*
Circulating water heater means an
instantaneous or heat pump-type water
heater that does not have an operational
scheme in which the burner, heating
element, or compressor initiates and/or
terminates heating based on sensing
flow; has a water temperature sensor
located at the inlet or the outlet of the
water heater or in a separate storage
tank that is the primary means of
initiating and terminating heating; and
must be used in combination with a
recirculating pump and either a separate
storage tank or water circulation loop in
order to achieve the water flow and
temperature conditions recommended
in the manufacturer’s installation and
operation instructions.
*
*
*
*
*
Low-temperature water heater means
an electric instantaneous water heater
that is not a circulating water heater and
cannot deliver water at a temperature
greater than or equal to the set point
temperature specified in section 2.5 of
appendix E to subpart B of this part
when supplied with water at the supply
water temperature specified in section
2.3 of appendix E to subpart B of this
part and the flow rate specified in
section 5.2.2.1 of appendix E to subpart
B of this part.
*
*
*
*
*
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Tabletop water heater means a heater
in a rectangular box enclosure designed
to slide into a kitchen countertop space
with typical dimensions of 36 inches
high, 25 inches deep, and 24 inches
wide.
*
*
*
*
*
■ 6. Section 430.3 is amended by:
■ a. In paragraph (g)(5), removing the
text ‘‘appendices E, AA’’ and adding, in
its place, the text ‘‘appendices AA’’;
■ b. Redesignating paragraph (g)(20) as
paragraph (g)(22);
■ c. Redesignating paragraph (g)(8)
through (19) as paragraphs (g)(9)
through (20);
■ d. Adding new paragraph (g)(8);
■ e. In newly redesignated paragraph
(g)(13), removing the text ‘‘F and EE’’
and adding, in its place, the text ‘‘E, F,
and EE’’;
■ f. Adding new paragraph (g)(21);
■ g. Revising paragraph (j).
The revisions and additions read as
follows:
*
*
*
*
(g) * * *
(8) ANSI/ASHRAE Standard 41.1–
2020 (‘‘ASHRAE 41.1–2020’’), Standard
Methods for Temperature Measurement,
ANSI-approved June 30, 2020; IBR
approved for appendix E to subpart B.
*
*
*
*
*
(21) ANSI/ASHRAE Standard 118.2–
2022 (‘‘ASHRAE 118.2–2022’’), Method
of Testing for Rating Residential Water
Heaters and Residential-Duty
Commercial Water Heaters, ANSIapproved March 1, 2022; IBR approved
for appendix E to subpart B.
*
*
*
*
*
(j) ASTM. ASTM International, 100
Barr Harbor Drive, P.O. Box C700, West
Conshohocken, PA 19428–2959; 877–
909–2786; service@astm.org;
www.astm.org.
(1) ASTM D2156–09 (Reapproved
2013) (‘‘ASTM D2156R13’’), Standard
Test Method for Smoke Density in Flue
Gases from Burning Distillate Fuels,
approved October 1, 2013; IBR approved
for appendix N to subpart B.
(2) ASTM D2156–09 (Reapproved
2018) (‘‘ASTM D2156 (R2018)’’),
Standard Test Method for Smoke
Density in Flue Gases from Burning
Distillate Fuels, approved October 1,
2018; IBR approved for appendices E, O,
and EE to subpart B.
(3) ASTM E97–82 (Reapproved 1987)
(‘‘ASTM E97–1987’’), Standard Test
Method for Directional Reflectance
Factor, 45-deg 0-deg, of Opaque
Specimens by Broad-Band Filter
Reflectometry, ASTM-approved October
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29, 1982; IBR approved for appendix E
to subpart B.
Note 2 to paragraph (j)(3): ASTM E97–
1987 was withdrawn in 1991. It is reasonably
available from standards resellers including
GlobalSpec’s Engineering 360 (https://
standards.globalspec.com/std/3801495/astme97-82-1987) and IHS Markit (https://
global.ihs.com/doc_detail.cfm?document_
name=ASTM%20E97&item_s_
key=00020483).
(4) ASTM E741–11 (Reapproved 2017)
(‘‘ASTM E741–11(2017)’’), Standard
Test Method for Determining Air
Change in a Single Zone Means of a
Tracer Gas Dilution Approved Sept. 1,
2017; IBR approved for appendix FF to
subpart B.
*
*
*
*
*
■ 7. Appendix E to subpart B of part 430
is revised to read as follows:
Appendix E to Subpart B of Part 430—
Uniform Test Method for Measuring the
Energy Consumption of Water Heaters
Note: Prior to December 18, 2023,
representations with respect to the energy
use or efficiency of consumer water heaters
covered by this test method, including
compliance certifications, must be based on
testing conducted in accordance with either
this appendix as it now appears or appendix
E as it appeared at 10 CFR part 430, subpart
B revised as of January 1, 2021.
On and after December 18, 2023,
representations with respect to energy use or
efficiency of consumer water heaters covered
by this test method, including compliance
certifications, must be based on testing
conducted in accordance with this appendix,
except as outlined in the following
paragraphs.
Prior to June 17, 2024, representations with
respect to the energy use or efficiency of
residential-duty commercial water heaters
covered by this test method, including
compliance certifications, must be based on
testing conducted in accordance with either
this appendix as it now appears or appendix
E as it appeared at 10 CFR part 430, subpart
B revised as of January 1, 2021.
On and after June 17, 2024, representations
with respect to energy use or efficiency of
residential-duty commercial water heaters
covered by this test method, including
compliance certifications, must be based on
testing conducted in accordance with this
appendix.
Water heaters subject to section 4.10 of this
appendix may optionally apply the
requirements in section 4.10 of this appendix
prior to the compliance date of a final rule
reviewing potential amended energy
conservation standards for these products
and equipment published after June 21, 2023.
After the compliance date of such standards
final rule, the requirements of section 4.10
are mandatory.
In addition, certain electric resistance
storage water heaters may optionally apply
the requirements in section 5.1.2 of this
appendix in lieu of the requirements in
section 5.1.1 of this appendix for additional
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voluntary representations only. Water heaters
must certify according to the requirements in
section 5.1.1 until the publication of a final
rule reviewing potential amended energy
conservation standards and specifying the
required use of section 5.1.2 for these
products published after June 21, 2023.
0. Incorporation by Reference.
DOE incorporated by reference in § 430.3
the entire standard for: ASHRAE 41.1–2020;
ASHRAE 41.6–2014; ASHRAE 118.2–2022;
ASTM D2156–09 (R2018); and ASTM E97–
1987. However, only enumerated provisions
of ASHRAE 118.2–2022 are applicable to this
appendix, as follows:
0.1 ASHRAE 118.2–2022
(a) Annex B—Gas Heating Value Correction
Factor;
(b) [Reserved]
0.2 [Reserved]
1. Definitions.
1.1. Cut-in means the time when or water
temperature at which a water heater control
or thermostat acts to increase the energy or
fuel input to the heating elements,
compressor, or burner.
1.2. Cut-out means the time when or water
temperature at which a water heater control
or thermostat acts to reduce to a minimum
the energy or fuel input to the heating
elements, compressor, or burner.
1.3. Design Power Rating means the power
rating or input rate that a water heater
manufacturer assigns to a particular design of
water heater and that is included on the
nameplate of the water heater, expressed in
kilowatts or Btu (kJ) per hour as appropriate.
For modulating water heaters, the design
power rating is the maximum power rating or
input rate that is specified by the
manufacturer on the nameplate of the water
heater.
1.4. Draw Cluster means a collection of
water draws initiated during the 24-hour
simulated-use test during which no
successive draws are separated by more than
2 hours.
1.5. First-Hour Rating means an estimate of
the maximum volume of ‘‘hot’’ water that a
non-flow activated water heater can supply
within an hour that begins with the water
heater fully heated (i.e., with all thermostats
satisfied).
1.6. Flow-Activated describes an
operational scheme in which a water heater
initiates and terminates heating based on
sensing flow.
1.7. Heat Trap means a device that can be
integrally connected or independently
attached to the hot and/or cold water pipe
connections of a water heater such that the
device will develop a thermal or mechanical
seal to minimize the recirculation of water
due to thermal convection between the water
heater tank and its connecting pipes.
1.8. Maximum GPM (L/min) Rating means
the maximum gallons per minute (liters per
minute) of hot water that can be supplied by
a flow-activated water heater when tested in
accordance with section 5.3.2 of this
appendix.
1.9. Modulating Water Heater means a
water heater that can automatically vary its
power or input rate from the minimum to the
maximum power or input rate specified on
the nameplate of the water heater by the
manufacturer.
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1.10. Rated Storage Volume means the
water storage capacity of a water heater, in
gallons (liters), as certified by the
manufacturer pursuant to 10 CFR part 429.
1.11. Recovery Efficiency means the ratio of
energy delivered to the water to the energy
content of the fuel consumed by the water
heater.
1.12. Recovery Period means the time when
the main burner of a water heater with a
rated storage volume greater than or equal to
2 gallons is raising the temperature of the
stored water.
1.13. Split-system heat pump water heater
means a heat pump-type water heater in
which at least the compressor, which may be
installed outdoors, is separate from the
storage tank.
1.14. Standby means the time, in hours,
during which water is not being withdrawn
from the water heater.
1.15. Symbol Usage. The following identity
relationships are provided to help clarify the
symbology used throughout this procedure:
Cp—specific heat of water
Eannual—annual energy consumption of a
water heater
Eannual,e—annual electrical energy
consumption of a water heater
Eannual,f—annual fossil-fuel energy
consumption of a water heater
EX—energy efficiency of a heat pump-type
water heater when the 24-hour simulated
use test is optionally conducted at any of
the additional air temperature conditions
as specified in section 2.8 of this appendix,
where the subscript ‘‘X’’ corresponds to the
dry-bulb temperature at which the test is
conducted.
Fhr—first-hour rating of a non-flow activated
water heater
Fmax—maximum GPM (L/min) rating of a
flow-activated water heater
i—a subscript to indicate the draw number
during a test
kV—storage tank volume scaling ratio for
water heaters with a rated storage volume
greater than or equal to 2 gallons
Mdel,i—mass of water removed during the ith
draw of the 24-hour simulated-use test
Min,i—mass of water entering the water heater
during the ith draw of the 24-hour
simulated-use test
M*del,i—for non-flow activated water heaters,
mass of water removed during the ith draw
during the first-hour rating test
M*in,i—for non-flow activated water heaters,
mass of water entering the water heater
during the ith draw during the first-hour
rating test
Mdel,10m—for flow-activated water heaters,
mass of water removed continuously
during the maximum GPM (L/min) rating
test
Min,10m—for flow-activated water heaters,
mass of water entering the water heater
continuously during the maximum GPM
(L/min) rating test
n—for non-flow activated water heaters, total
number of draws during the first-hour
rating test
N—total number of draws during the 24-hour
simulated-use test
Nr—number of draws from the start of the 24hour simulated-use test to the end to the
first recovery period as described in
section 5.4.2 of this appendix
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Q—total fossil fuel and/or electric energy
consumed during the entire 24-hour
simulated-use test
Qd—daily water heating energy consumption
adjusted for net change in internal energy
Qda—Qd with adjustment for variation of tank
to ambient air temperature difference from
nominal value
Qdm—overall adjusted daily water heating
energy consumption including Qda and
QHWD
Qe—total electrical energy used during the
24-hour simulated-use test
Qf—total fossil fuel energy used by the water
heater during the 24-hour simulated-use
test
Qhr—hourly standby losses of a water heater
with a rated storage volume greater than or
equal to 2 gallons
QHW—daily energy consumption to heat
water at the measured average temperature
rise across the water heater
QHW,67 °F—daily energy consumption to heat
quantity of water removed during test over
a temperature rise of 67 °F (37.3 °C)
QHWD—adjustment to daily energy
consumption, QHW, due to variation of the
temperature rise across the water heater
not equal to the nominal value of 67 °F
(37.3 °C)
Qr—energy consumption of water heater from
the beginning of the test to the end of the
first recovery period
Qstby—total energy consumed during the
standby time interval tstby,1, as determined
in section 5.4.2 of this appendix
Qsu,0—cumulative energy consumption,
including all fossil fuel and electrical
energy use, of the water heater from the
start of the 24-hour simulated-use test to
the start of the standby period as
determined in section 5.4.2 of this
appendix
Qsu,f—cumulative energy consumption,
including all fossil fuel and electrical
energy use, of the water heater from the
start of the 24-hour simulated-use test to
the end of the standby period as
determined in section 5.4.2 of this
appendix
T0—mean tank temperature at the beginning
of the 24-hour simulated-use test as
determined in section 5.4.2 of this
appendix
T24—mean tank temperature at the end of the
24-hour simulated-use test as determined
in section 5.4.2 of this appendix
Ta,stby—average ambient air temperature
during all standby periods of the 24-hour
simulated-use test as determined in section
5.4.2 of this appendix
Ta,stby,1—overall average ambient temperature
between the start and end of the standby
period as determined in section 5.4.2 of
this appendix
Tt,stby,1— overall average mean tank
temperature between the start and end of
the standby period as determined in
section 5.4.2 of this appendix
Tdel—for flow-activated water heaters,
average outlet water temperature during
the maximum GPM (L/min) rating test
Tdel,i—average outlet water temperature
during the ith draw of the 24-hour
simulated-use test
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Tin—for flow-activated water heaters, average
inlet water temperature during the
maximum GPM (L/min) rating test
Tst—for water heaters which cannot have
internal tank temperature directly
measured, estimated average internal
storage tank temperature
Tp—for water heaters which cannot have
internal tank temperature directly
measured, average of the inlet and the
outlet water temperatures at the end of the
period defined by tp
Tin,p—for water heaters which cannot have
internal tank temperature directly
measured, average of the inlet water
temperatures
Tout,p—for water heaters which cannot have
internal tank temperature directly
measured, average of the outlet water
temperatures
Tin,i—average inlet water temperature during
the ith draw of the 24-hour simulated-use
test
Tmax,1—maximum measured mean tank
temperature after the first recovery period
of the 24-hour simulated-use test as
determined in section 5.4.2 of this
appendix
Tsu,0—maximum measured mean tank
temperature at the beginning of the standby
period as determined in section 5.4.2 of
this appendix
Tsu,f—measured mean tank temperature at the
end of the standby period as determined in
section 5.4.2 of this appendix
T*del,i—for non-flow activated water heaters,
average outlet water temperature during
the ith draw (i = 1 to n) of the first-hour
rating test
T*max,i—for non-flow activated water heaters,
maximum outlet water temperature
observed during the ith draw (i = 1 to n)
of the first-hour rating test
T*min,i—for non-flow activated water heaters,
minimum outlet water temperature to
terminate the ith draw (i = 1 to n) of the
first-hour rating test
UA—standby loss coefficient of a water
heater with a rated storage volume greater
than or equal to 2 gallons
UEF—uniform energy factor of a water heater
V—the volume of hot water drawn during the
applicable draw pattern
Vdel,i—volume of water removed during the
ith draw (i = 1 to N) of the 24-hour
simulated-use test
Vin,i—volume of water entering the water
heater during the ith draw (i = 1 to N) of
the 24-hour simulated-use test
V*del,i—for non-flow activated water heaters,
volume of water removed during the ith
draw (i = 1 to n) of the first-hour rating test
V*in,i—for non-flow activated water heaters,
volume of water entering the water heater
during the ith draw (i = 1 to n) of the firsthour rating test
Vdel,10m—for flow-activated water heaters,
volume of water removed during the
maximum GPM (L/min) rating test
Vin,10m—for flow-activated water heaters,
volume of water entering the water heater
during the maximum GPM (L/min) rating
test
Vst—measured storage volume of the storage
tank for water heaters with a rated storage
volume greater than or equal to 2 gallons
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Veff—effective storage volume
vout,p—for water heaters which cannot have
internal tank temperature directly
measured, average flow rate
Wf—weight of storage tank when completely
filled with water for water heaters with a
rated storage volume greater than or equal
to 2 gallons
Wt—tare weight of storage tank when
completely empty of water for water
heaters with a rated storage volume greater
than or equal to 2 gallons
hr—recovery efficiency
r—density of water
tp—for water heaters which cannot have
internal tank temperature directly
measured, duration of the temperature
measurement period, determined by the
length of time taken for the outlet water
temperature to be within 2 °F of the inlet
water temperature for 15 consecutive
seconds (including the 15-second
stabilization period)
tstby,1—elapsed time between the start and
end of the standby period as determined in
section 5.4.2 of this appendix
tstby,2—overall time of standby periods when
no water is withdrawn during the 24-hour
simulated-use test as determined in section
5.4.2 of this appendix
1.16. Temperature Controller means a
device that is available to the user to adjust
the temperature of the water inside a water
heater that stores heated water or the outlet
water temperature.
1.17. Thermal break means a thermally
non-conductive material that can withstand a
pressure of 150 psi (1.034 MPa) at a
temperature greater than the maximum
temperature the water heater is designed to
produce and is utilized to insulate a bypass
loop, if one is used in the test set-up, from
the inlet piping.
1.18. Uniform Energy Factor means the
measure of water heater overall efficiency.
1.19. Water Heater Requiring a Storage
Tank means a water heater without a storage
tank specified or supplied by the
manufacturer that cannot meet the
requirements of sections 2 and 5 of this
appendix without the use of a storage water
heater or unfired hot water storage tank.
2. Test Conditions.
2.1 Installation Requirements. Tests shall
be performed with the water heater and
instrumentation installed in accordance with
section 4 of this appendix.
2.2 Ambient Air Temperature and
Relative Humidity.
2.2.1 Non-Heat Pump Water Heaters. The
ambient air temperature shall be maintained
between 65.0 °F and 70.0 °F (18.3 °C and
21.1 °C) on a continuous basis.
2.2.2 Heat Pump Water Heaters. The drybulb temperature shall be maintained at an
average of 67.5 °F ± 1 °F (19.7 °C ± 0.6 °C)
after a cut-in and before the next cut-out, an
average of 67.5 °F ± 2.5 °F (19.7 °C ± 1.4 °C)
after a cut-out and before the next cut-in, and
at 67.5 °F ± 5 °F (19.7 °C ± 2.8 °C) on a
continuous basis throughout the test. The
relative humidity shall be maintained within
a range of 50% ± 5% throughout the test, and
at an average of 50% ± 2% after a cut-in and
before the next cut-out.
When testing a split-system heat pump
water heater or heat pump water heater
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requiring a separate storage tank, the heat
pump portion of the system shall be tested
at the conditions within this section and the
separate water heater or unfired hot water
storage tank shall be tested at either the
conditions within this section or the
conditions specified in section 2.2.1 of this
appendix.
2.3 Supply Water Temperature. The
temperature of the water being supplied to
the water heater shall be maintained at 58 °F
± 2 °F (14.4 °C ± 1.1 °C) throughout the test.
2.4 Outlet Water Temperature. The
temperature controllers of a non-flow
activated water heater shall be set so that
water is delivered at a temperature of 125 °F
± 5 °F (51.7 °C ± 2.8 °C).
2.5 Set Point Temperature. The
temperature controller of a flow-activated
water heater shall be set to deliver water at
a temperature of 125 °F ± 5 °F (51.7 °C ±
2.8 °C). If the flow-activated water heater is
not capable of delivering water at a
temperature of 125 °F ± 5 °F (51.7 °C ± 2.8 °C)
when supplied with water at the supply
water temperature specified in section 2.3 of
this appendix, then the flow-activated water
heater shall be set to deliver water at its
maximum water temperature.
2.6 Supply Water Pressure. During the
test when water is not being withdrawn, the
supply pressure shall be maintained between
40 psig (275 kPa) and the maximum
allowable pressure specified by the water
heater manufacturer.
2.7 Electrical and/or Fossil Fuel Supply.
2.7.1 Electrical. Maintain the electrical
supply voltage to within ±2% of the center
of the voltage range specified on the
nameplate of the water heater by the water
heater and/or heat pump manufacturer, from
5 seconds after a cut-in to 5 seconds before
next cut-out.
2.7.2 Natural Gas. Maintain the supply
pressure in accordance with the supply
pressure specified on the nameplate of the
water heater by the manufacturer. If the
supply pressure is not specified, maintain a
supply pressure of 7–10 inches of water
column (1.7–2.5 kPa). If the water heater is
equipped with a gas appliance pressure
regulator and the gas appliance pressure
regulator can be adjusted, the regulator outlet
pressure shall be within the greater of ±10%
of the manufacturer’s specified manifold
pressure, found on the nameplate of the
water heater, or ±0.2 inches water column
(0.05 kPa). Maintain the gas supply pressure
and manifold pressure only when operating
at the design power rating. For all tests, use
natural gas having a heating value of
approximately 1,025 Btu per standard cubic
foot (38,190 kJ per standard cubic meter).
2.7.3 Propane Gas. Maintain the supply
pressure in accordance with the supply
pressure specified on the nameplate of the
water heater by the manufacturer. If the
supply pressure is not specified, maintain a
supply pressure of 11–13 inches of water
column (2.7–3.2 kPa). If the water heater is
equipped with a gas appliance pressure
regulator and the gas appliance pressure
regulator can be adjusted, the regulator outlet
pressure shall be within the greater of ±10%
of the manufacturer’s specified manifold
pressure, found on the nameplate of the
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water heater, or ±0.2 inches water column
(0.05 kPa). Maintain the gas supply pressure
and manifold pressure only when operating
at the design power rating. For all tests, use
propane gas with a heating value of
approximately 2,500 Btu per standard cubic
foot (93,147 kJ per standard cubic meter).
2.7.4 Fuel Oil Supply. Maintain an
uninterrupted supply of fuel oil. The fuel
pump pressure shall be within ±10% of the
pump pressure specified on the nameplate of
the water heater or the installation and
operations (I&O) manual by the
manufacturer. Use fuel oil having a heating
value of approximately 138,700 Btu per
gallon (38,660 kJ per liter).
2.8 Optional Test Conditions (Heat
Pump-Type Water Heaters). The following
test conditions may be used for optional
representations of EX for heat pump-type
water heaters. When conducting a 24-hour
simulated use test to determine EX, the test
conditions in section 2.1 and sections 2.4
through 2.7 apply. The ambient air
temperature and humidity conditions in
section 2.2 and the supply water temperature
in section 2.3 are replaced with the air
temperature, humidity, and supply water
temperature conditions as shown in the
following table. Testing may optionally be
performed at any or all of the conditions in
the table, and the sampling plan found at 10
CFR 429.17(a) may be applied for voluntary
representations.
Outdoor air conditions
Heat pump type
Metric
Split-System or Circulating .................................
Integrated, Split-System, or Circulating ..............
3. Instrumentation.
Dry-bulb
temperature
(°F)
E5
E34
E95
E50
E95
Relative
humidity
(%)
5.0
34.0
95.0
N/A
N/A
30
72
25
N/A
N/A
Item measured
Instrument accuracy
Gas pressure ...................................
Atmospheric pressure .....................
Water pressure ................................
±0.1 inch of water column (±0.025 kPa) ...................
±0.1 inch of mercury column (±0.34 kPa) .................
±1.0 pounds per square inch (±6.9 kPa) ...................
Relative
humidity
(%)
67.5
........................
........................
50.0
95.0
50
........................
........................
58
40
Supply water
temperature
(°F)
42.0
47.0
67.0
50.0
67.0
Instrument precision
3.2.3 Scale Division. In no case shall the
smallest scale division of the instrument or
instrument system exceed 2 times the
specified precision.
3.2.4 Temperature Difference.
Temperature difference between the entering
and leaving water may be measured with any
of the following:
(a) A thermopile
(b) Calibrated resistance thermometers
(c) Precision thermometers
(d) Calibrated thermistors
(e) Calibrated thermocouples
(f) Quartz thermometers
3.2.5 Thermopile Construction. If a
thermopile is used, it shall be made from
calibrated thermocouple wire taken from a
single spool. Extension wires to the recording
device shall also be made from that same
spool.
3.2.6 Time Constant. The time constant of
the instruments used to measure the inlet
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3.2.2 Accuracy and Precision. The
accuracy and precision of the instruments,
including their associated readout devices,
shall be within the following limits:
Instrument accuracy
Air dry-bulb temperature .........................................................................
Air wet-bulb temperature .........................................................................
Inlet and outlet water temperatures ........................................................
Storage tank temperatures ......................................................................
19:48 Jun 20, 2023
±0.05 inch of water column (±0.012 kPa).
±0.05 inch of mercury column (±0.17 kPa).
±0.50 pounds per square inch (±3.45 kPa).
the conditions as specified in ASHRAE 41.6–
2014 as referenced in ASHRAE 41.1–2020,
and excluding the steady-state temperature
criteria in section 5.5 of ASHRAE 41.1–2020.
Item measured
VerDate Sep<11>2014
Dry-bulb
temperature
(°F)
3.1 Pressure Measurements. Pressuremeasuring instruments shall have an error no
greater than the following values:
3.2 Temperature Measurement
3.2.1 Measurement. Temperature
measurements shall be made in accordance
with the Standard Method for Temperature
Measurement, ASHRAE 41.1–2020, including
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Indoor air conditions
±0.2
±0.2
±0.2
±0.5
°F
°F
°F
°F
(±0.1
(±0.1
(±0.1
(±0.3
°C)
°C)
°C)
°C)
...........................
...........................
...........................
...........................
and outlet water temperatures shall be no
greater than 2 seconds.
3.3 Liquid Flow Rate Measurement. The
accuracy of the liquid flow rate
measurement, using the calibration if
furnished, shall be equal to or less than ±1%
of the measured value in mass units per unit
time.
3.4 Electrical Energy. The electrical
energy used shall be measured with an
instrument and associated readout device
that is accurate within ±0.5% of the reading.
3.5 Fossil Fuels. The quantity of fuel used
by the water heater shall be measured with
an instrument and associated readout device
that is accurate within ±1% of the reading.
3.6 Mass Measurements. For mass
measurements greater than or equal to 10
pounds (4.5 kg), a scale that is accurate
within ±0.5% of the reading shall be used to
make the measurement. For mass
measurements less than 10 pounds (4.5 kg),
the scale shall provide a measurement that is
accurate within ±0.1 pound (0.045 kg).
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Instrument precision
±0.1 °F (±0.06 °C).
±0.1 °F (±0.06 °C).
±0.1 °F (±0.06 °C).
±0.25 °F (±0.14 °C).
3.7 Heating Value. The higher heating
value of the natural gas, propane, or fuel oil
shall be measured with an instrument and
associated readout device that is accurate
within ±1% of the reading. The heating
values of natural gas and propane must be
corrected from those measured to the
standard temperature of 60.0 °F (15.6 °C) and
standard pressure of 30 inches of mercury
column (101.6 kPa) using the method
described in Annex B of ASHRAE 118.2–
2022.
3.8 Time. The elapsed time
measurements shall be measured with an
instrument that is accurate within ±0.5
seconds per hour.
3.9 Volume. Volume measurements shall
be measured with an accuracy of ±2% of the
total volume.
3.10 Relative Humidity. If a relative
humidity (RH) transducer is used to measure
the relative humidity of the surrounding air
while testing heat pump water heaters, the
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relative humidity shall be measured with an
accuracy of ±1.5% RH.
4. Installation.
4.1 Water Heater Mounting. A water
heater designed to be freestanding shall be
placed on a 3⁄4 inch (2 cm) thick plywood
platform supported by three 2x4 inch (5
cm x 10 cm) runners. If the water heater is not
approved for installation on combustible
flooring, suitable non-combustible material
shall be placed between the water heater and
the platform. Water heaters designed to be
installed into a kitchen countertop space
shall be placed against a simulated wall
section. Wall-mounted water heaters shall be
supported on a simulated wall in accordance
with the manufacturer-published installation
instructions. When a simulated wall is used,
the construction shall be 2x4 inch (5 cm x 10
cm) studs, faced with 3⁄4 inch (2 cm)
plywood. For heat pump water heaters not
delivered as a single package, the units shall
be connected in accordance with the
manufacturer-published installation
instructions, and the overall system shall be
placed on the above-described plywood
platform. If installation instructions are not
provided by the heat pump manufacturer,
uninsulated 8 foot (2.4 m) long connecting
hoses having an inside diameter of 5⁄8 inch
(1.6 cm) shall be used to connect the storage
tank and the heat pump water heater. With
the exception of using the storage tank
described in section 4.10 of this appendix,
the same requirements shall apply for water
heaters requiring a storage tank. The testing
of the water heater shall occur in an area that
is protected from drafts of more than 50 ft/
min (0.25 m/s) from room ventilation
registers, windows, or other external sources
of air movement.
4.2 Water Supply. Connect the water
heater to a water supply capable of delivering
water at conditions as specified in sections
2.3 and 2.6 of this appendix.
4.3 Water Inlet and Outlet Configuration.
For freestanding water heaters that are taller
than 36 inches (91.4 cm), inlet and outlet
piping connections shall be configured in a
manner consistent with Figures 1 and 2 of
section 7 of this appendix. Inlet and outlet
piping connections for wall-mounted water
heaters shall be consistent with Figure 3 of
section 7 of this appendix. For freestanding
water heaters that are 36 inches or less in
height and not supplied as part of a countertop enclosure (commonly referred to as an
under-the-counter model), inlet and outlet
piping shall be installed in a manner
consistent with Figures 4, 5, or 6 of section
7 of this appendix. For water heaters that are
supplied with a counter-top enclosure, inlet
and outlet piping shall be made in a manner
consistent with Figures 7a and 7b of section
7 of this appendix, respectively. The vertical
piping noted in Figures 7a and 7b shall be
located (whether inside the enclosure or
along the outside in a recessed channel) in
accordance with the manufacturer-published
installation instructions.
All dimensions noted in Figures 1 through
7 of section 7 of this appendix must be
achieved. All piping between the water
heater and inlet and outlet temperature
sensors, noted as TIN and TOUT in the figures,
shall be Type ‘‘L’’ hard copper having the
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same diameter as the connections on the
water heater. Unions may be used to facilitate
installation and removal of the piping
arrangements. Install a pressure gauge and
diaphragm expansion tank in the supply
water piping at a location upstream of the
inlet temperature sensor. Install an
appropriately rated pressure and temperature
relief valve on all water heaters at the port
specified by the manufacturer. Discharge
piping for the relief valve must be nonmetallic. If heat traps, piping insulation, or
pressure relief valve insulation are supplied
with the water heater, they must be installed
for testing. Except when using a simulated
wall, provide sufficient clearance such that
none of the piping contacts other surfaces in
the test room.
At the discretion of the test laboratory, the
mass or water delivered may be measured on
either the inlet or outlet of the water heater.
For water heaters designed to be used with
a mixing valve and that do not have a selfcontained mixing valve, a mixing valve shall
be installed according to the water heater
and/or mixing valve manufacturer’s
installation instructions. If permitted by the
water heater and mixing valve
manufacturer’s instructions, the mixing valve
and cold water junction may be installed
where the elbows are located in the outlet
and inlet line, respectively. If there are no
installation instructions for the mixing valve
in the water heater or mixing valve
manufacturer’s instructions, then the mixing
valve shall be installed on the outlet line and
the cold water shall be supplied from the
inlet line from a junction installed
downstream from the location where the
inlet water temperature is measured. The
outlet water temperature, water flow rate,
and/or mass measuring instrumentation, if
installed on the outlet side of the water
heater, shall be installed downstream from
the mixing valve.
4.4 Fuel and/or Electrical Power and
Energy Consumption. Install one or more
instruments that measure, as appropriate, the
quantity and rate of electrical energy and/or
fossil fuel consumption in accordance with
section 3 of this appendix.
4.5 Internal Storage Tank Temperature
Measurements. For water heaters with rated
storage volumes greater than or equal to 20
gallons, install six temperature measurement
sensors inside the water heater tank with a
vertical distance of at least 4 inches (100 mm)
between successive sensors. For water
heaters with rated storage volumes between
2 and 20 gallons, install three temperature
measurement sensors inside the water heater
tank. Position a temperature sensor at the
vertical midpoint of each of the six equal
volume nodes within a tank larger than 20
gallons or the three equal volume nodes
within a tank between 2 and 20 gallons.
Nodes designate the equal volumes used to
evenly partition the total volume of the tank.
As much as is possible, the temperature
sensor should be positioned away from any
heating elements, anodic protective devices,
tank walls, and flue pipe walls. If the tank
cannot accommodate six temperature sensors
and meet the installation requirements
specified in this section, install the
maximum number of sensors that comply
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with the installation requirements. Install the
temperature sensors through:
(a) The anodic device opening;
(b) The relief valve opening; or
(c) The hot water outlet.
If installed through the relief valve opening
or the hot water outlet, a tee fitting or outlet
piping, as applicable, must be installed as
close as possible to its original location. If the
relief valve temperature sensor is relocated,
and it no longer extends into the top of the
tank, install a substitute relief valve that has
a sensing element that can reach into the
tank. If the hot water outlet includes a heat
trap, install the heat trap on top of the tee
fitting. Cover any added fittings with thermal
insulation having an R value between 4 and
8 h·ft2· °F/Btu (0.7 and 1.4 m2· °C/W). If
temperature measurement sensors cannot be
installed within the water heater, follow the
alternate procedures in section 5.4.2.2 of this
appendix.
4.6 Ambient Air Temperature
Measurement. Install an ambient air
temperature sensor at the vertical midpoint
of the water heater and approximately 2 feet
(610 mm) from the surface of the water
heater. Shield the sensor against radiation.
4.7 Inlet and Outlet Water Temperature
Measurements. Install temperature sensors in
the cold-water inlet pipe and hot-water outlet
pipe as shown in Figures 1, 2, 3, 4, 5, 6, 7a,
and 7b of section 7 of this appendix, as
applicable.
4.8 Flow Control. Install a valve or valves
to provide flow as specified in sections 5.3
and 5.4 of this appendix.
4.9 Flue Requirements.
4.9.1 Gas-Fired Water Heaters. Establish a
natural draft in the following manner. For
gas-fired water heaters with a vertically
discharging draft hood outlet, connect to the
draft hood outlet a 5-foot (1.5-meter) vertical
vent pipe extension with a diameter equal to
the largest flue collar size of the draft hood.
For gas-fired water heaters with a
horizontally discharging draft hood outlet,
connect to the draft hood outlet a 90-degree
elbow with a diameter equal to the largest
flue collar size of the draft hood, connect a
5-foot (1.5-meter) length of vent pipe to that
elbow, and orient the vent pipe to discharge
vertically upward. Install direct-vent gasfired water heaters with venting equipment
specified by the manufacturer in the I&O
manual using the minimum vertical and
horizontal lengths of vent pipe recommended
by the manufacturer.
4.9.2 Oil-Fired Water Heaters. Establish a
draft at the flue collar at the value specified
by the manufacturer in the I&O manual.
Establish the draft by using a sufficient
length of vent pipe connected to the water
heater flue outlet, and directed vertically
upward. For an oil-fired water heater with a
horizontally discharging draft hood outlet,
connect to the draft hood outlet a 90-degree
elbow with a diameter equal to the largest
flue collar size of the draft hood, connect to
the elbow fitting a length of vent pipe
sufficient to establish the draft, and orient the
vent pipe to discharge vertically upward.
Direct-vent oil-fired water heaters should be
installed with venting equipment as specified
by the manufacturer in the I&O manual,
using the minimum vertical and horizontal
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lengths of vent pipe recommended by the
manufacturer.
4.10 Storage Tank Requirement for
Circulating Water Heaters. On or after the
compliance date of a final rule reviewing
potential amended energy conservation
standards for these products published after
June 21, 2023,when testing a gas-fired, oilfired, or electric resistance circulating water
heater (i.e., any circulating water heater that
does not use a heat pump), the tank to be
used for testing shall be an unfired hot water
storage tank having volume between 80 and
120 gallons (364–546 liters) determined using
the method specified in section 5.2.1 that
meets but does not exceed the minimum
energy conservation standards required
according to 10 CFR 431.110. When testing
a heat pump circulating water heater, the
tank to be used for testing shall be an electric
storage water heater that has a measured
volume of 40 gallons (±5 gallons), has a FirstHour Rating greater than or equal to 51
gallons and less than 75 gallons resulting in
classification under the medium draw
pattern, and has a rated UEF equal to the
minimum UEF standard specified at
§ 430.32(d), rounded to the nearest 0.01. The
operational mode of the heat pump
circulating water heater and storage water
heater paired system shall be set in
accordance with section 5.1.1 of this
appendix. If the circulating water heater is
supplied with a separate non-integrated
circulating pump, install this pump as per
the manufacturer’s installation instructions
and include its power consumption in energy
use measurements.
4.11 External Communication. If the
water heater can connect to an external
network or controller, any external
communication or connection shall be
disabled for the duration of testing; however,
the communication module shall remain in
an ‘‘on’’ state.
5. Test Procedures.
5.1 Operational Mode Selection. For
water heaters that allow for multiple userselected operational modes, all procedures
specified in this appendix shall be carried
out with the water heater in the same
operational mode (i.e., only one mode).
5.1.1 Testing at Normal Setpoint. The
operational mode shall be the default mode
(or similarly named, suggested mode for
normal operation) as defined by the
manufacturer in the I&O manual for giving
selection guidance to the consumer. For heat
pump water heaters, if a default mode is not
defined in the product literature, each test
shall be conducted under an operational
mode in which both the heat pump and any
electric resistance back-up heating element(s)
are activated by the unit’s control scheme,
and which can achieve the internal storage
tank temperature specified in this test
procedure; if multiple operational modes
meet these criteria, the water heater shall be
tested under the most energy-intensive mode.
If no default mode is specified and the unit
does not offer an operational mode that
utilizes both the heat pump and the electric
resistance back-up heating element(s), the
first-hour rating test and the 24-hour
simulated-use test shall be tested in heatpump-only mode. For other types of water
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heaters where a default mode is not
specified, test the unit in all modes and rate
the unit using the results of the most energyintensive mode.
5.1.2 High Temperature Testing. This
paragraph applies to electric storage water
heaters that are capable of heating their
stored water above the target delivery
temperature without initiation from a utility
or third-party demand-response program,
except for those that meet the definition of
‘‘heat pump-type’’ water heater at 10 CFR
430.2.
For those equipped with factory-installed
or built-in mixing valves, set the unit to
maintain the highest mean tank temperature
possible while delivering water at 125 °F ±
5 °F. For those not so equipped, install an
ASSE 1017-certified mixing valve in
accordance with the provisions in section 4.3
and adjust the valve to deliver water at 125 °F
± 5 °F when the water heater is operating at
its highest storage tank temperature setpoint.
Maintain this setting throughout the entirety
of the test.
5.2 Water Heater Preparation.
5.2.1 Determination of Storage Tank
Volume. For water heaters with a rated
storage volume greater than or equal to 2
gallons and for separate storage tanks used
for testing circulating water heaters,
determine the storage capacity, Vst, of the
water heater or separate storage tank under
test, in gallons (liters), by subtracting the tare
weight, Wt, (measured while the tank is
empty) from the gross weight of the storage
tank when completely filled with water at the
supply water temperature specified in
section 2.3 of this appendix, Wf, (with all air
eliminated and line pressure applied as
described in section 2.6 of this appendix) and
dividing the resulting net weight by the
density of water at the measured
temperature.
5.2.2 Setting the Outlet Discharge
Temperature.
5.2.2.1 Flow-Activated Water Heaters,
including certain instantaneous water
heaters and certain storage-type water
heaters. Initiate normal operation of the
water heater at the design power rating.
Monitor the discharge water temperature and
set to the value specified in section 2.5 of this
appendix in accordance with the
manufacturer’s I&O manual. If the water
heater is not capable of providing this
discharge temperature when the flow rate is
1.7 gallons ± 0.25 gallons per minute (6.4
liters ± 0.95 liters per minute), then adjust
the flow rate as necessary to achieve the
specified discharge water temperature. Once
the proper temperature control setting is
achieved, the setting must remain fixed for
the duration of the maximum GPM test and
the 24-hour simulated-use test.
5.2.2.2 All Other Water Heaters.
5.2.2.2.1 Water Heaters with a Single
Temperature Controller.
5.2.2.2.1.1 Water Heaters with Rated
Volumes Less than 20 Gallons. Starting with
a tank at the supply water temperature as
specified in section 2.3 of this appendix,
initiate normal operation of the water heater.
After cut-out, initiate a draw from the water
heater at a flow rate of 1.0 gallon ± 0.25
gallons per minute (3.8 liters ± 0.95 liters per
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minute) for 2 minutes. Starting 15 seconds
after commencement of the draw, record the
outlet temperature at 15-second intervals
until the end of the 2-minute period.
Determine whether the maximum outlet
temperature is within the range specified in
section 2.4 of this appendix. If not, turn off
the water heater, adjust the temperature
controller, and then drain and refill the tank
with supply water at the temperature
specified in section 2.3 of this appendix.
Then, once again, initiate normal operation
of the water heater, and repeat the 2-minute
outlet temperature test following cut-out.
Repeat this sequence until the maximum
outlet temperature during the 2-minute test is
within the range specified in section 2.4 of
this appendix. Once the proper temperature
control setting is achieved, the setting must
remain fixed for the duration of the first-hour
rating test and the 24-hour simulated-use
test.
5.2.2.2.1.2 Water Heaters with Rated
Volumes Greater than or Equal to 20 Gallons.
Starting with a tank at the supply water
temperature specified in section 2.3 of this
appendix, initiate normal operation of the
water heater. After cut-out, initiate a draw
from the water heater at a flow rate of 1.7
gallons ± 0.25 gallons per minute (6.4 liters
± 0.95 liters per minute) for 5 minutes.
Starting 15 seconds after commencement of
the draw, record the outlet temperature at 15second intervals until the end of the 5minute period. Determine whether the
maximum outlet temperature is within the
range specified in section 2.4 of this
appendix. If not, turn off the water heater,
adjust the temperature controller, and then
drain and refill the tank with supply water
at the temperature specified in section 2.3 of
this appendix. Then, once again, initiate
normal operation of the water heater, and
repeat the 5-minute outlet temperature test
following cut-out. Repeat this sequence until
the maximum outlet temperature during the
5-minute test is within the range specified in
section 2.4 of this appendix. Once the proper
temperature control setting is achieved, the
setting must remain fixed for the duration of
the first-hour rating test and the 24-hour
simulated-use test.
5.2.2.2.2 Water Heaters with Two or More
Temperature Controllers. Verify the
temperature controller set-point while
removing water in accordance with the
procedure set forth for the first-hour rating
test in section 5.3.3 of this appendix. The
following criteria must be met to ensure that
all temperature controllers are set to deliver
water in the range specified in section 2.4 of
this appendix:
(a) At least 50 percent of the water drawn
during the first draw of the first-hour rating
test procedure shall be delivered at a
temperature within the range specified in
section 2.4 of this appendix.
(b) No water is delivered above the range
specified in section 2.4 of this appendix
during first-hour rating test.
(c) The delivery temperature measured 15
seconds after commencement of each draw
begun prior to an elapsed time of 60 minutes
from the start of the test shall be within the
range specified in section 2.4 of this
appendix.
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If these conditions are not met, turn off the
water heater, adjust the temperature
controllers, and then drain and refill the tank
with supply water at the temperature
specified in section 2.3 of this appendix.
Repeat the procedure described at the start of
section 5.2.2.2.2 of this appendix until the
criteria for setting the temperature controllers
is met.
If the conditions stated above are met, the
data obtained during the process of verifying
the temperature control set-points may be
used in determining the first-hour rating
provided that all other conditions and
methods required in sections 2 and 5.2.4 of
this appendix in preparing the water heater
were followed.
5.2.3 Power Input Determination. For all
water heaters except electric types, initiate
normal operation (as described in section 5.1
of this appendix) and determine the power
input, P, to the main burners (including pilot
light power, if any) after 15 minutes of
operation. Adjust all burners to achieve an
hourly Btu (kJ) rating that is within ±2% of
the maximum input rate value specified by
the manufacturer. For an oil-fired water
heater, adjust the burner to give a CO2
reading recommended by the manufacturer
and an hourly Btu (kJ) rating that is within
±2% of the maximum input rate specified by
the manufacturer. Smoke in the flue may not
exceed No. 1 smoke as measured by the
procedure in ASTM D2156 (R2018),
including the conditions as specified in
ASTM E97–1987 as referenced in ASTM
D2156 (R2018). If the input rating is not
within ±2%, first increase or decrease the
fuel pressure within the tolerances specified
in section 2.7.2, 2.7.3 or 2.7.4 (as applicable)
of this appendix until it is ±2% of the
maximum input rate value specified by the
manufacturer. If, after adjusting the fuel
pressure, the fuel input rate cannot be
achieved within ±2 percent of the maximum
input rate value specified by the
manufacturer, for gas-fired models increase
or decrease the gas supply pressure within
the range specified by the manufacturer.
Finally, if the measured fuel input rate is still
not within ±2 percent of the maximum input
rate value specified by the manufacturer,
modify the gas inlet orifice, if so equipped,
as necessary to achieve a fuel input rate that
is within ±2 percent of the maximum input
rate value specified by the manufacturer.
5.2.4 Soak-In Period for Water Heaters
with Rated Storage Volumes Greater than or
Equal to 2 Gallons. For water heaters with a
rated storage volume greater than or equal to
2 gallons (7.6 liters), the water heater must
sit filled with water, connected to a power
source, and without any draws taking place
for at least 12 hours after initially being
energized so as to achieve the nominal
temperature set-point within the tank and
with the unit connected to a power source.
5.3 Delivery Capacity Tests.
5.3.1 General. For flow-activated water
heaters, conduct the maximum GPM test, as
described in section 5.3.2, Maximum GPM
Rating Test for Flow-Activated Water
Heaters, of this appendix. For all other water
heaters, conduct the first-hour rating test as
described in section 5.3.3 of this appendix.
5.3.2 Maximum GPM Rating Test for
Flow-Activated Water Heaters. Establish
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normal water heater operation at the design
power rating with the discharge water
temperature set in accordance with section
5.2.2.1 of this appendix.
For this 10-minute test, either collect the
withdrawn water for later measurement of
the total mass removed or use a water meter
to directly measure the water mass of volume
removed. Initiate water flow through the
water heater and record the inlet and outlet
water temperatures beginning 15 seconds
after the start of the test and at subsequent
5-second intervals throughout the duration of
the test. At the end of 10 minutes, turn off
the water. Determine and record the mass of
water collected, M10m, in pounds (kilograms),
or the volume of water, V10m, in gallons
(liters).
5.3.3 First-Hour Rating Test.
5.3.3.1 General. During hot water draws
for water heaters with rated storage volumes
greater than or equal to 20 gallons, remove
water at a rate of 3.0 ± 0.25 gallons per
minute (11.4 ± 0.95 liters per minute). During
hot water draws for water heaters with rated
storage volumes below 20 gallons, remove
water at a rate of 1.5 ± 0.25 gallon per minute
(5.7 ± 0.95 liters per minute). Collect the
water in a container that is large enough to
hold the volume removed during an
individual draw and is suitable for weighing
at the termination of each draw to determine
the total volume of water withdrawn. As an
alternative to collecting the water, a water
meter may be used to directly measure the
water mass or volume withdrawn during
each draw.
5.3.3.2 Draw Initiation Criteria. Begin the
first-hour rating test by starting a draw on the
water heater. After completion of this first
draw, initiate successive draws based on the
following criteria. For gas-fired and oil-fired
water heaters, initiate successive draws when
the temperature controller acts to reduce the
supply of fuel to the main burner. For electric
water heaters having a single element or
multiple elements that all operate
simultaneously, initiate successive draws
when the temperature controller acts to
reduce the electrical input supplied to the
element(s). For electric water heaters having
two or more elements that do not operate
simultaneously, initiate successive draws
when the applicable temperature controller
acts to reduce the electrical input to the
energized element located vertically highest
in the storage tank. For heat pump water
heaters that do not use supplemental,
resistive heating, initiate successive draws
immediately after the electrical input to the
compressor is reduced by the action of the
water heater’s temperature controller. For
heat pump water heaters that use
supplemental resistive heating, initiate
successive draws immediately after the
electrical input to the first of either the
compressor or the vertically highest resistive
element is reduced by the action of the
applicable water heater temperature
controller. This draw initiation criterion for
heat pump water heaters that use
supplemental resistive heating, however,
shall only apply when the water located
above the thermostat at cut-out is heated to
within the range specified in section 2.4 of
this appendix. If this criterion is not met,
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then the next draw should be initiated once
the heat pump compressor cuts out.
5.3.3.3 Test Sequence. Establish normal
water heater operation. If the water heater is
not presently operating, initiate a draw. The
draw may be terminated any time after cutin occurs. After cut-out occurs (i.e., all
temperature controllers are satisfied), if the
water heater can have its internal tank
temperatures measured, record the internal
storage tank temperature at each sensor
described in section 4.5 of this appendix
every one minute, and determine the mean
tank temperature by averaging the values
from these sensors.
Initiate a draw after a maximum mean tank
temperature (the maximum of the mean
temperatures of the individual sensors) has
been observed following a cut-out. If the
water heater cannot have its internal tank
temperatures measured, wait 5 minutes after
cut-out. Record the time when the draw is
initiated and designate it as an elapsed time
of zero (t* = 0). (The superscript * is used
to denote variables pertaining to the firsthour rating test). Record the outlet water
temperature beginning 15 seconds after the
draw is initiated and at 5-second intervals
thereafter until the draw is terminated.
Determine the maximum outlet temperature
that occurs during this first draw and record
it as T*max,1. For the duration of this first
draw and all successive draws, in addition,
monitor the inlet temperature to the water
heater to ensure that the required supply
water temperature test condition specified in
section 2.3 of this appendix is met.
Terminate the hot water draw when the
outlet temperature decreases to
T*max,1¥15 °F (T*max,1¥8.3 °C). (Note, if the
outlet temperature does not decrease to
T*max,1¥15 °F (T*max,1¥8.3 °C) during the
draw, then hot water would be drawn
continuously for the duration of the test. In
this instance, the test would end when the
temperature decreases to T*max,1¥15 °F
(T*max,1¥8.3 °C) after the electrical power
and/or fuel supplied to the water heater is
shut off, as described in the following
paragraphs.) Record this temperature as
T*min,1. Following draw termination,
determine the average outlet water
temperature and the mass or volume
removed during this first draw and record
them as T*del,i and M*1 or V*1, respectively.
Initiate a second and, if applicable,
successive draw(s) each time the applicable
draw initiation criteria described in section
5.3.3.2 of this appendix are satisfied. As
required for the first draw, record the outlet
water temperature 15 seconds after initiating
each draw and at 5-second intervals
thereafter until the draw is terminated.
Determine the maximum outlet temperature
that occurs during each draw and record it
as T*max,i, where the subscript i refers to the
draw number. Terminate each hot water
draw when the outlet temperature decreases
to T*max,i¥15 °F (T*max,i¥8.3 °C). Record this
temperature as T*min,i. Calculate and record
the average outlet temperature and the mass
or volume removed during each draw (T*del,i
and M*i or V*i, respectively). Continue this
sequence of draw and recovery until one
hour after the start of the test, then shut off
the electrical power and/or fuel supplied to
the water heater.
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If a draw is occurring at one hour from the
start of the test, continue this draw until the
outlet temperature decreases to
T*max,n¥15 °F (T*max,n¥8.3 °C), at which
time the draw shall be immediately
terminated. (The subscript n shall be used to
denote measurements associated with the
final draw.) If a draw is not occurring one
hour after the start of the test, initiate a final
draw at one hour, regardless of whether the
criteria described in section 5.3.3.2 of this
appendix are satisfied. This draw shall
proceed for a minimum of 30 seconds and
shall terminate when the outlet temperature
first indicates a value less than or equal to
the cut-off temperature used for the previous
draw (T*min,n¥1). If an outlet temperature
greater than T*min,n¥1 is not measured within
30 seconds of initiation of the draw, zero
additional credit shall be given towards firsthour rating (i.e., M*n = 0 or V*n = 0) based
on the final draw. After the final draw is
terminated, calculate and record the average
outlet temperature and the mass or volume
removed during the final draw (T*del,n and
M*n or V*n, respectively).
5.4 24-Hour Simulated-Use Test.
5.4.1 Selection of Draw Pattern. The
water heater will be tested under a draw
profile that depends upon the first-hour
rating obtained following the test prescribed
in section 5.3.3 of this appendix, or the
maximum GPM rating obtained following the
test prescribed in section 5.3.2 of this
appendix, whichever is applicable. For water
heaters that have been tested according to the
first-hour rating procedure, one of four
different patterns shall be applied based on
the measured first-hour rating, as shown in
Table I of this section. For water heater that
have been tested according to the maximum
GPM rating procedure, one of four different
patterns shall be applied based on the
maximum GPM, as shown in Table II of this
section.
TABLE I—DRAW PATTERN TO BE USED BASED ON FIRST-HOUR RATING
First-hour rating greater than or equal to:
. . . and first-hour rating less than:
0 gallons ..................................................
18 gallons ................................................
51 gallons ................................................
75 gallons ................................................
18 gallons ..............................................
51 gallons ..............................................
75 gallons ..............................................
No upper limit ........................................
Draw pattern to be used in the 24-hour simulated-use test
Very-Small-Usage (Table III.1).
Low-Usage (Table III.2).
Medium-Usage (Table III.3).
High-Usage (Table III.4).
lotter on DSK11XQN23PROD with RULES2
TABLE II—DRAW PATTERN TO BE USED BASED ON MAXIMUM GPM RATING
Maximum GPM rating greater than or
equal to:
and maximum GPM rating less than:
0 gallons/minute ......................................
1.7 gallons/minute ...................................
2.8 gallons/minute ...................................
4 gallons/minute ......................................
1.7 gallons/minute .................................
2.8 gallons/minute .................................
4 gallons/minute ....................................
No upper limit ........................................
The draw patterns are provided in Tables
III.1 through III.4 in section 5.5 of this
appendix. Use the appropriate draw pattern
when conducting the test sequence provided
in section 5.4.2 of this appendix for water
heaters with rated storage volumes greater
than or equal to 2 gallons or section 5.4.3 of
this appendix for water heaters with rated
storage volumes less than 2 gallons.
5.4.2 Test Sequence for Water Heater
With Rated Storage Volume Greater Than or
Equal to 2 Gallons.
If the water heater is turned off, fill the
water heater with supply water at the
temperature specified in section 2.3 of this
appendix and maintain supply water
pressure as described in section 2.6 of this
appendix. Turn on the water heater and
associated heat pump unit, if present. If
turned on in this fashion, the soak-in period
described in section 5.2.4 of this appendix
shall be implemented. If the water heater has
undergone a first-hour rating test prior to
conduct of the 24-hour simulated-use test,
allow the water heater to fully recover after
completion of that test such that the main
burner, heating elements, or heat pump
compressor of the water heater are no longer
raising the temperature of the stored water.
In all cases, the water heater shall sit idle for
1 hour prior to the start of the 24-hour test;
during which time no water is drawn from
the unit, and there is no energy input to the
main heating elements, heat pump
compressor, and/or burners.
For water heaters that can have their
internal storage tank temperature measured
directly, perform testing in accordance with
the instructions in section 5.4.2.1 of this
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Draw pattern to be used in the 24-hour simulated-use test
Very-Small-Usage (Table III.1).
Low-Usage (Table III.2).
Medium-Usage (Table III.3).
High-Usage (Table III.4).
appendix. For water heaters that cannot have
their internal tank temperatures measured,
perform testing in accordance with the
instructions in section 5.4.2.2. of this
appendix.
5.4.2.1 Water Heaters Which Can Have
Internal Storage Tank Temperature
Measured Directly.
After the 1-hour period specified in section
5.4.2 of this appendix, the 24-hour
simulated-use test will begin. One minute
prior to the start of the 24-hour simulated-use
test, record the mean tank temperature (T0).
At the start of the 24-hour simulated-use
test, record the electrical and/or fuel
measurement readings, as appropriate. Begin
the 24-hour simulated-use test by
withdrawing the volume specified in the
appropriate table in section 5.5 of this
appendix (i.e., Table III.1, Table III.2, Table
III.3, or Table III.4, depending on the firsthour rating or maximum GPM rating) for the
first draw at the flow rate specified in the
applicable table. Record the time when this
first draw is initiated and assign it as the test
elapsed time (t) of zero (0). Record the
average storage tank and ambient
temperature every minute throughout the 24hour simulated-use test. At the elapsed times
specified in the applicable draw pattern table
in section 5.5 of this appendix for a
particular draw pattern, initiate additional
draws pursuant to the draw pattern,
removing the volume of hot water at the
prescribed flow rate specified by the table.
The maximum allowable deviation from the
specified volume of water removed for any
single draw taken at a nominal flow rate of
1.0 GPM or 1.7 GPM is ±0.1 gallons (±0.4
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liters). The maximum allowable deviation
from the specified volume of water removed
for any single draw taken at a nominal flow
rate of 3.0 GPM is ±0.25 gallons (0.9 liters).
The quantity of water withdrawn during the
last draw shall be increased or decreased as
necessary such that the total volume of water
withdrawn equals the prescribed daily
amount for that draw pattern ±1.0 gallon
(±3.8 liters). If this adjustment to the volume
drawn during the last draw results in no
draw taking place, the test is considered
invalid.
All draws during the 24-hour simulateduse test shall be made at the flow rates
specified in the applicable draw pattern table
in section 5.5 of this appendix, within a
tolerance of ±0.25 gallons per minute (±0.9
liters per minute). Measurements of the inlet
and outlet temperatures shall be made 15
seconds after the draw is initiated and at
every subsequent 3-second interval
throughout the duration of each draw.
Calculate and record the mean of the hot
water discharge temperature and the cold
water inlet temperature for each draw Tdel,i
and Tin,i). Determine and record the net mass
or volume removed (Mi or Vi), as appropriate,
after each draw.
The first recovery period is the time from
the start of the 24-hour simulated-use test
and continues during the temperature rise of
the stored water until the first cut-out; if the
cut-out occurs during a subsequent draw, the
first recovery period includes the time until
the draw of water from the tank stops. If, after
the first cut-out occurs but during a
subsequent draw, a subsequent cut-in occurs
prior to the draw completion, the first
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21JNR2
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recovery period includes the time until the
subsequent cut-out occurs, prior to another
draw. The first recovery period may continue
until a cut-out occurs when water is not
being removed from the water heater or a cutout occurs during a draw and the water
heater does not cut-in prior to the end of the
draw.
At the end of the first recovery period,
record the maximum mean tank temperature
observed after cut-out (Tmax,1). At the end of
the first recovery period, record the total
energy consumed by the water heater from
the beginning of the test (Qr), including all
fossil fuel and/or electrical energy use, from
the main heat source and auxiliary
equipment including, but not limited to,
burner(s), resistive elements(s), compressor,
fan, controls, pump, etc., as applicable.
The start of the portion of the test during
which the standby loss coefficient is
determined depends upon whether the unit
has fully recovered from the first draw
cluster. If a recovery is occurring at or within
five minutes after the end of the final draw
in the first draw cluster, as identified in the
applicable draw pattern table in section 5.5
of this appendix, then the standby period
starts when a maximum mean tank
temperature is observed starting five minutes
after the end of the recovery period that
follows that draw. If a recovery does not
occur at or within five minutes after the end
of the final draw in the first draw cluster, as
identified in the applicable draw pattern
table in section 5.5 of this appendix, then the
standby period starts five minutes after the
end of that draw. Determine and record the
total electrical energy and/or fossil fuel
consumed from the beginning of the test to
the start of the standby period (Qsu,0).
In preparation for determining the energy
consumed during standby, record the reading
given on the electrical energy (watt-hour)
meter, the gas meter, and/or the scale used
to determine oil consumption, as
appropriate. Record the mean tank
temperature at the start of the standby period
(Tsu,0). At 1-minute intervals, record ambient
temperature, the electric and/or fuel
instrument readings, and the mean tank
temperature until the next draw is initiated.
The end of the standby period is when the
final mean tank temperature is recorded, as
described. Just prior to initiation of the next
draw, record the mean tank temperature
(Tsu,f). If the water heater is undergoing
recovery when the next draw is initiated,
record the mean tank temperature (Tsu,f) at
the minute prior to the start of the recovery.
Determine the total electrical energy and/or
fossil fuel energy consumption from the
beginning of the test to the end of the standby
period (Qsu,f). Record the time interval
between the start of the standby period and
the end of the standby period (tstby,1).
Following the final draw of the prescribed
draw pattern and subsequent recovery, allow
the water heater to remain in the standby
mode until exactly 24 hours have elapsed
since the start of the 24-hour simulated-use
test (i.e., since t = 0). During the last hour
of the 24-hour simulated-use test (i.e., hour
23 of the 24-hour simulated-use test), power
to the main burner, heating element, or
compressor shall be disabled. At 24 hours,
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record the reading given by the gas meter, oil
meter, and/or the electrical energy meter as
appropriate. Determine the fossil fuel and/or
electrical energy consumed during the entire
24-hour simulated-use test and designate the
quantity as Q.
In the event that the recovery period
continues from the end of the last draw of the
first draw cluster until the subsequent draw,
the standby period will start after the end of
the first recovery period after the last draw
of the 24-hour simulated-use test, when the
temperature reaches the maximum mean tank
temperature, though no sooner than five
minutes after the end of this recovery period.
The standby period shall last eight hours, so
testing may extend beyond the 24-hour
duration of the 24-hour simulated-use test.
Determine and record the total electrical
energy and/or fossil fuel consumed from the
beginning of the 24-hour simulated-use test
to the start of the 8-hour standby period
(Qsu,0). In preparation for determining the
energy consumed during standby, record the
reading(s) given on the electrical energy
(watt-hour) meter, the gas meter, and/or the
scale used to determine oil consumption, as
appropriate. Record the mean tank
temperature at the start of the standby period
(Tsu,0). Record the mean tank temperature, the
ambient temperature, and the electric and/or
fuel instrument readings at 1-minute
intervals until the end of the 8-hour period.
Record the mean tank temperature at the end
of the 8-hour standby period (Tsu,f). If the
water heater is undergoing recovery at the
end of the standby period, record the mean
tank temperature (Tsu,f) at the minute prior to
the start of the recovery, which will mark the
end of the standby period. Determine the
total electrical energy and/or fossil fuel
energy consumption from the beginning of
the test to the end of the standby period
(Qsu,f). Record the time interval between the
start of the standby period and the end of the
standby period as tstby,1. Record the average
ambient temperature from the start of the
standby period to the end of the standby
period (Ta,stby,1). Record the average mean
tank temperature from the start of the
standby period to the end of the standby
period (Tt,stby,1).
If the standby period occurred at the end
of the first recovery period after the last draw
of the 24-hour simulated-use test, allow the
water heater to remain in the standby mode
until exactly 24 hours have elapsed since the
start of the 24-hour simulated-use test (i.e.,
since t = 0) or the end of the standby period,
whichever is longer. At 24 hours, record the
mean tank temperature (T24) and the reading
given by the gas meter, oil meter, and/or the
electrical energy meter as appropriate. If the
water heater is undergoing a recovery at 24
hours, record the reading given by the gas
meter, oil meter, and/or electrical energy
meter, as appropriate, and the mean tank
temperature (T24) at the minute prior to the
start of the recovery. Determine the fossil fuel
and/or electrical energy consumed during the
24 hours and designate the quantity as Q.
Record the time during which water is not
being withdrawn from the water heater
during the entire 24-hour period (tstby,2).
When the standby period occurs after the last
draw of the 24-hour simulated-use test, the
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40481
test may extend past hour 24. When this
occurs, the measurements taken after hour 24
apply only to the calculations of the standby
loss coefficient. All other measurements
during the time between hour 23 and hour
24 remain the same.
5.4.2.2 Water Heaters Which Cannot
Have Internal Storage Tank Temperature
Measured Directly.
After the water heater has undergone a 1hour idle period (as described in section
5.4.2 of this appendix), deactivate the burner,
compressor, or heating element(s).
Remove water from the storage tank by
performing a continuous draw at the flow
rate specified for the first draw of applicable
draw pattern for the 24-hour simulated use
test in section 5.5 of this appendix within a
tolerance of ±0.25 gallons per minute (±0.9
liters per minute). While removing the hot
water, measure the inlet and outlet
temperature after initiating the draw at 3second intervals. Remove water until the
outlet water temperature is within ±2 °F (±1.1
°C) of the inlet water temperature for 15
consecutive seconds. Determine the mean
tank temperature using section 6.3.77 of this
appendix and assign this value of Tst for T0,
Tmax,1, and Tsu,0.
After completing the draw, reactivate the
burner, compressor, or heating elements(s)
and allow the unit to fully recover such that
the main burner, heating elements, or heat
pump compressor is no longer raising the
temperature of the stored water. Let the water
heater sit idle again for 1 hour prior to
beginning the 24-hour test, during which
time no water shall be drawn from the unit,
and there shall be no energy input to the
main heating elements. After the 1-hour
period, the 24-hour simulated-use test will
begin.
At the start of the 24-hour simulated-use
test, record the electrical and/or fuel
measurement readings, as appropriate. Begin
the 24-hour simulated-use test by
withdrawing the volume specified in the
appropriate table in section 5.5 of this
appendix (i.e., Table III.1, Table III.2, Table
III.3, or Table III.4, depending on the firsthour rating or maximum GPM rating) for the
first draw at the flow rate specified in the
applicable table. Record the time when this
first draw is initiated and assign it as the test
elapsed time (t) of zero (0). Record the
average ambient temperature every minute
throughout the 24-hour simulated-use test. At
the elapsed times specified in the applicable
draw pattern table in section 5.5 of this
appendix for a particular draw pattern,
initiate additional draws pursuant to the
draw pattern, removing the volume of hot
water at the prescribed flow rate specified by
the table. The maximum allowable deviation
from the specified volume of water removed
for any single draw taken at a nominal flow
rate of 1.0 GPM or 1.7 GPM is ± 0.1 gallons
(± 0.4 liters). The maximum allowable
deviation from the specified volume of water
removed for any single draw taken at a
nominal flow rate of 3.0 GPM is ± 0.25
gallons (0.9 liters). The quantity of water
withdrawn during the last draw shall be
increased or decreased as necessary such that
the total volume of water withdrawn equals
the prescribed daily amount for that draw
E:\FR\FM\21JNR2.SGM
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Federal Register / Vol. 88, No. 118 / Wednesday, June 21, 2023 / Rules and Regulations
pattern ± 1.0 gallon (± 3.8 liters). If this
adjustment to the volume drawn during the
last draw results in no draw taking place, the
test is considered invalid.
All draws during the 24-hour simulateduse test shall be made at the flow rates
specified in the applicable draw pattern table
in section 5.5 of this appendix, within a
tolerance of ±0.25 gallons per minute (±0.9
liters per minute). Measurements of the inlet
and outlet temperatures shall be made 15
seconds after the draw is initiated and at
every subsequent 3-second interval
throughout the duration of each draw.
Calculate and record the mean of the hot
water discharge temperature and the cold
water inlet temperature for each draw Tdel,i
and Tin,i). Determine and record the net mass
or volume removed (Mi or Vi), as appropriate,
after each draw.
The first recovery period is the time from
the start of the 24-hour simulated-use test
and continues until the first cut-out; if the
cut-out occurs during a subsequent draw, the
first recovery period includes the time until
the draw of water from the tank stops. If, after
the first cut-out occurs but during a
subsequent draw, a subsequent cut-in occurs
prior to the draw completion, the first
recovery period includes the time until the
subsequent cut-out occurs, prior to another
draw. The first recovery period may continue
until a cut-out occurs when water is not
being removed from the water heater or a cutout occurs during a draw and the water
heater does not cut-in prior to the end of the
draw.
At the end of the first recovery period,
record the total energy consumed by the
water heater from the beginning of the test
(Qr), including all fossil fuel and/or electrical
energy use, from the main heat source and
auxiliary equipment including, but not
limited to, burner(s), resistive elements(s),
compressor, fan, controls, pump, etc., as
applicable.
The standby period begins at five minutes
after the first time a recovery ends following
last draw of the simulated-use test and shall
continue for 8 hours. At the end of the 8-hour
standby period, record the total amount of
time elapsed since the start of the 24-hour
simulated-use test (i.e., since t = 0).
Determine and record the total electrical
energy and/or fossil fuel consumed from the
beginning of the 24-hour simulated-use test
to the start of the 8-hour standby period
(Qsu,0). In preparation for determining the
energy consumed during standby, record the
reading(s) given on the electrical energy
(watt-hour) meter, the gas meter, and/or the
scale used to determine oil consumption, as
appropriate. Record the ambient temperature
and the electric and/or fuel instrument
readings at 1-minute intervals until the end
of the 8-hour period. At the 8-hour mark,
deactivate the water heater before drawing
water from the tank. Remove water from the
storage tank by performing a continuous
draw atthe flow rate specified for the first
draw of applicable draw pattern for the 24hour simulated use test in section 5.5 of this
appendix within a tolerance of ±0.25 gallons
per minute (±0.9 liters per minute). While
removing the hot water, measure the inlet
and outlet temperature after initiating the
draw at 3-second intervals. Remove water
until the outlet water temperature is within
±2 °F (±1.1 °C) of the inlet water temperature
for 15 consecutive seconds. Determine the
mean tank temperature using section 6.3.77
of this appendix and assign this value of Tst
for Tsu,f and T24.
Determine the total electrical energy and/
or fossil fuel energy consumption from the
beginning of the test to the end of the standby
period (Qsu,f). Record the time interval
between the start of the standby period and
the end of the standby period as tstby,1.
Record the average ambient temperature from
the start of the standby period to the end of
the standby period (Ta,stby,1). The average
mean tank temperature from the start of the
standby period to the end of the standby
period (Tt,stby,1) shall be the average of Tsu,0
and Tsu,f.
5.4.3 Test Sequence for Water Heaters
With Rated Storage Volume Less Than 2
Gallons.
Establish normal operation with the
discharge water temperature at 125 °F ± 5 °F
(51.7 °C ± 2.8 °C) and set the flow rate as
determined in section 5.2 of this appendix.
Prior to commencement of the 24-hour
simulated-use test, the unit shall remain in
an idle state in which controls are active but
no water is drawn through the unit for a
period of one hour. With no draw occurring,
record the reading given by the gas meter
and/or the electrical energy meter as
appropriate. Begin the 24-hour simulated-use
test by withdrawing the volume specified in
Tables III.1 through III.4 of section 5.5 of this
appendix for the first draw at the flow rate
specified. Record the time when this first
draw is initiated and designate it as an
elapsed time, t, of 0. At the elapsed times
specified in Tables III.1 through III.4 for a
particular draw pattern, initiate additional
draws, removing the volume of hot water at
the prescribed flow rate specified in Tables
III.1 through III.4. The maximum allowable
deviation from the specified volume of water
removed for any single draw taken at a
nominal flow rate less than or equal to 1.7
GPM (6.4 L/min) is ±0.1 gallons (±0.4 liters).
The maximum allowable deviation from the
specified volume of water removed for any
single draw taken at a nominal flow rate of
3.0 GPM (11.4 L/min) is ±0.25 gallons (0.9
liters). The quantity of water drawn during
the final draw shall be increased or decreased
as necessary such that the total volume of
water withdrawn equals the prescribed daily
amount for that draw pattern ±1.0 gallon
(±3.8 liters). If this adjustment to the volume
drawn in the last draw results in no draw
taking place, the test is considered invalid.
All draws during the 24-hour simulateduse test shall be made at the flow rates
specified in the applicable draw pattern table
in section 5.5 of this appendix within a
tolerance of ±0.25 gallons per minute (±0.9
liters per minute) unless the unit being tested
is flow-activated and has a rated Max GPM
of less than 1 gallon per minute, in which
case the tolerance shall be ±25% of the rated
Max GPM. Measurements of the inlet and
outlet water temperatures shall be made 15
seconds after the draw is initiated and at
every 3-second interval thereafter throughout
the duration of the draw. Calculate the mean
of the hot water discharge temperature and
the cold-water inlet temperature for each
draw. Record the mass of the withdrawn
water or the water meter reading, as
appropriate, after each draw. At the end of
the first recovery period following the first
draw, determine and record the fossil fuel
and/or electrical energy consumed, Qr.
Following the final draw and subsequent
recovery, allow the water heater to remain in
the standby mode until exactly 24 hours have
elapsed since the start of the test (i.e., since
t = 0). At 24 hours, record the reading given
by the gas meter, oil meter, and/or the
electrical energy meter, as appropriate.
Determine the fossil fuel and/or electrical
energy consumed during the entire 24-hour
simulated-use test and designate the quantity
as Q.
5.5 Draw Patterns.
The draw patterns to be imposed during
24-hour simulated-use tests are provided in
Tables III.1 through III.4. Subject each water
heater under test to one of these draw
patterns based on its first-hour rating or
maximum GPM rating, as discussed in
section 5.4.1 of this appendix. Each draw
pattern specifies the elapsed time in hours
and minutes during the 24-hour test when a
draw is to commence, the total volume of
water in gallons (liters) that is to be removed
during each draw, and the flow rate at which
each draw is to be taken, in gallons (liters)
per minute.
TABLE III.1—VERY-SMALL-USAGE DRAW PATTERN
Time during
test **
[hh:mm]
lotter on DSK11XQN23PROD with RULES2
Draw No.
1 * .................................................................................................................................................
2 * .................................................................................................................................................
3 * .................................................................................................................................................
4 * .................................................................................................................................................
5 * .................................................................................................................................................
6 ...................................................................................................................................................
7 ...................................................................................................................................................
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E:\FR\FM\21JNR2.SGM
0:00
1:00
1:05
1:10
1:15
8:00
8:15
21JNR2
Volume
[gallons (L)]
2.0
1.0
0.5
0.5
0.5
1.0
2.0
(7.6)
(3.8)
(1.9)
(1.9)
(1.9)
(3.8)
(7.6)
Flow rate ***
[GPM (L/min)]
1
1
1
1
1
1
1
(3.8)
(3.8)
(3.8)
(3.8)
(3.8)
(3.8)
(3.8)
Federal Register / Vol. 88, No. 118 / Wednesday, June 21, 2023 / Rules and Regulations
40483
TABLE III.1—VERY-SMALL-USAGE DRAW PATTERN—Continued
Time during
test **
[hh:mm]
Draw No.
8 ...................................................................................................................................................
9 ...................................................................................................................................................
9:00
9:15
Volume
[gallons (L)]
1.5 (5.7)
1.0 (3.8)
Flow rate ***
[GPM (L/min)]
1 (3.8)
1 (3.8)
Total Volume Drawn Per Day: 10 gallons (38 L)
* Denotes draws in first draw cluster.
** If a draw extends to the start of the subsequent draw, then the subsequent draw shall start when the required volume of the previous draw
has been delivered.
*** Should the water heater have a maximum GPM rating less than 1 GPM (3.8 L/min), then all draws shall be implemented at a flow rate
equal to the rated maximum GPM.
TABLE III.2—LOW-USAGE DRAW PATTERN
Time during
test
[hh:mm]
Draw No.
1 * .................................................................................................................................................
2 * .................................................................................................................................................
3 * .................................................................................................................................................
4 ...................................................................................................................................................
5 ...................................................................................................................................................
6 ...................................................................................................................................................
7 ...................................................................................................................................................
8 ...................................................................................................................................................
9 ...................................................................................................................................................
10 .................................................................................................................................................
11 .................................................................................................................................................
0:00
0:30
1:00
10:30
11:30
12:00
12:45
12:50
16:15
16:45
17:00
Volume
[gallons (L)]
15.0 (56.8)
2.0 (7.6)
1.0 (3.8)
6.0 (22.7)
4.0 (15.1)
1.0 (3.8)
1.0 (3.8)
1.0 (3.8)
2.0 (7.6)
2.0 (7.6)
3.0 (11.4)
Flow rate
[GPM (L/min)]
1.7
1
1
1.7
1.7
1
1
1
1
1.7
1.7
(6.4)
(3.8)
(3.8)
(6.4)
(6.4)
(3.8)
(3.8)
(3.8)
(3.8)
(6.4)
(6.4)
Total Volume Drawn Per Day: 38 gallons (144 L)
*Denotes draws in first draw cluster.
TABLE III.3—MEDIUM-USAGE DRAW PATTERN
Time during
test
[hh:mm]
Draw No.
1 * .................................................................................................................................................
2 * .................................................................................................................................................
3 * .................................................................................................................................................
4 ...................................................................................................................................................
5 ...................................................................................................................................................
6 ...................................................................................................................................................
7 ...................................................................................................................................................
8 ...................................................................................................................................................
9 ...................................................................................................................................................
10 .................................................................................................................................................
11 .................................................................................................................................................
12 .................................................................................................................................................
0:00
0:30
1:40
10:30
11:30
12:00
12:45
12:50
16:00
16:15
16:45
17:00
Volume
[gallons (L)]
15.0 (56.8)
2.0 (7.6)
9.0 (34.1)
9.0 (34.1)
5.0 (18.9)
1.0 (3.8)
1.0 (3.8)
1.0 (3.8)
1.0 (3.8)
2.0 (7.6)
2.0 (7.6)
7.0 (26.5)
Flow Rate
[GPM (L/min)]
1.7
1
1.7
1.7
1.7
1
1
1
1
1
1.7
1.7
(6.4)
(3.8)
(6.4)
(6.4)
(6.4)
(3.8)
(3.8)
(3.8)
(3.8)
(3.8)
(6.4)
(6.4)
Total Volume Drawn Per Day: 55 gallons (208 L)
* Denotes draws in first draw cluster.
TABLE III.4—HIGH-USAGE DRAW PATTERN
Time during
test
[hh:mm]
lotter on DSK11XQN23PROD with RULES2
Draw No.
1 * .................................................................................................................................................
2 * .................................................................................................................................................
3 * .................................................................................................................................................
4 * .................................................................................................................................................
5 ...................................................................................................................................................
6 ...................................................................................................................................................
7 ...................................................................................................................................................
8 ...................................................................................................................................................
9 ...................................................................................................................................................
10 .................................................................................................................................................
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0:00
0:30
0:40
1:40
10:30
11:30
12:00
12:45
12:50
16:00
21JNR2
Volume
[gallons (L)]
27.0 (102)
2.0 (7.6)
1.0 (3.8)
9.0 (34.1)
15.0 (56.8)
5.0 (18.9)
1.0 (3.8)
1.0 (3.8)
1.0 (3.8)
2.0 (7.6)
Flow rate
[GPM (L/min)]
3 (11.4)
1 (3.8)
1 (3.8)
1.7 (6.4)
3 (11.4)
1.7 (6.4)
1 (3.8)
1 (3.8)
1 (3.8)
1 (3.8)
40484
Federal Register / Vol. 88, No. 118 / Wednesday, June 21, 2023 / Rules and Regulations
TABLE III.4—HIGH-USAGE DRAW PATTERN—Continued
Time during
test
[hh:mm]
Draw No.
11
12
13
14
.................................................................................................................................................
.................................................................................................................................................
.................................................................................................................................................
.................................................................................................................................................
16:15
16:30
16:45
17:00
Volume
[gallons (L)]
2.0 (7.6)
2.0 (7.6)
2.0 (7.6)
14.0 (53.0)
Flow rate
[GPM (L/min)]
1 (3.8)
1.7 (6.4)
1.7 (6.4)
3 (11.4)
Total Volume Drawn Per Day: 84 gallons (318 L)
* Denotes draws in first draw cluster.
Where:
n = the number of draws that are completed
during the first-hour rating test.
V*del,i = the volume of water removed during
the ith draw of the first-hour rating test,
gal (L) or, if the mass of water removed
is being measured,
Where:
M*del,i = the mass of water removed during
the ith draw of the first-hour rating test,
lb (kg).
rdel,i = the density of water removed,
evaluated at the average outlet water
temperature measured during the ith
draw of the first-hour rating test, (T*del,i),
lb/gal (kg/L).
or, if the volume of the water entering the
water heater is being measured,
V*in,i = the volume of water entering the
water heater during the ith draw of the
first-hour rating test, gal (L).
rin,i = the density of water entering the water
heater, evaluated at the average inlet
water temperature measured during the
ith draw of the first-hour rating test,
(T*in,i), lb/gal (kg/L).
or, if the mass of water entering the water
heater is being measured,
Where:
M*in,i = the mass of water entering the water
heater during the ith draw of the firsthour rating test, lb (kg).
For the case in which a draw is not in
progress at one hour from the start of the test
and a final draw is imposed at the elapsed
time of one hour, the first-hour rating shall
be calculated using,
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ER21JN23.010</GPH>
ER21JN23.011</GPH>
ER21JN23.012</GPH>
PO 00000
Where:
Vin,10m = the volume of water entering the
water heater during the maximum GPM
(L/min) rating test, gal (L).
rin = the density of water entering the water
heater, evaluated at the average inlet
ER21JN23.009</GPH>
Where:
Vdel,10m = the volume of water removed
during the maximum GPM (L/min) rating
test, gal (L).
Tdel = the average delivery temperature, °F
(°C).
Tin = the average inlet temperature, °F (°C).
10 = the number of minutes in the maximum
GPM (L/min) rating test, min.
or, if the mass of water removed is measured,
Where:
Mdel,10m = the mass of water removed during
the maximum GPM (L/min) rating test, lb
(kg).
rdel = the density of water removed,
evaluated at the average delivery water
temperature of the maximum GPM (L/
min) rating test (Tdel), lb/gal (kg/L).
or, if the volume of water entering the water
heater is measured,
ER21JN23.008</GPH>
where n and V*del,i are the same quantities as
defined above, and
V*del,n = the volume of water removed during
the nth (final) draw of the first-hour
rating test, gal (L).
T*del,n¥1 = the average water outlet
temperature measured during the
(n¥1)th draw of the first-hour rating test,
°F (°C).
T*del,n = the average water outlet temperature
measured during the nth (final) draw of
the first-hour rating test, °F (°C).
T*min,n¥1 = the minimum water outlet
temperature measured during the
(n¥1)th draw of the first-hour rating test,
°F (°C).
6.2 Maximum GPM (L/min) Rating
Computation. Compute the maximum GPM
(L/min) rating, Fmax, as:
ER21JN23.007</GPH>
lotter on DSK11XQN23PROD with RULES2
ER21JN23.013</GPH>
Where:
ER21JN23.014</GPH>
5.6 Optional Tests (Heat Pump-Type
Water Heaters). Optional testing may be
conducted on heat pump-type water heaters
to determine EX. If optional testing is
performed, conduct the additional 24-hour
simulated use test(s) at one or multiple of the
test conditions specified in section 2.8 of this
appendix. Prior to conducting a 24-hour
simulated use test at an optional condition,
confirm the air and water conditions
specified in section 2.8 are met and re-set the
outlet discharge temperature in accordance
with section 5.2.2 of this appendix. Perform
the optional 24-hour simulated use test(s) in
accordance with section 5.4 of this appendix
using the same draw pattern used for the
determination of UEF.
6. Computations.
6.1 First-Hour Rating Computation. For
the case in which the final draw is initiated
at or prior to one hour from the start of the
test, the first-hour rating, Fhr, shall be
computed using,
Federal Register / Vol. 88, No. 118 / Wednesday, June 21, 2023 / Rules and Regulations
Cp(Tmax,1) = the specific heat of the stored hot
water, evaluated at Tmax,1, Btu/(lb·°F) (kJ/
(kg·°C)).
r(125 °F) = the density of the stored hot water
at 125 °F, lb/gal (kg/L).
Cp(125 °F) = the specific heat of the stored hot
water at 125 °F, Btu/(lb·°F) (kJ/(kg·°C)).
125 °F (51.7 °C) = the nominal maximum
mean tank temperature for a storage tank
that does not utilize a mixing valve to
achieve a 125 °F delivery temperature.
67.5 °F (19.7 °C) = the nominal average
ambient air temperature.
6.3.2 Mass of Water Removed. Determine
the mass of water removed during each draw
of the 24-hour simulated-use test (Mdel,i) as:
If the mass of water removed is measured,
use the measured value, or, if the volume of
water removed is being measured,
Mdel,i = Vdel,i * Pdel,i
Where:
Vdel,i = volume of water removed during the
ith draw of the 24-hour simulated-use
test, gal (L).
rdel,i = density of the water removed,
evaluated at the average outlet water
temperature measured during the ith
draw of the 24-hour simulated-use test,
(Tdel,i), lb/gal (kg/L).
or, if the volume of water entering the water
heater is measured,
Mdel,i = Vin,i * rin,i
Where:
Vin,i = volume of water entering the water
heater during draw ith draw of the 24hour simulated-use test, gal (L).
rin,i = density of the water entering the water
heater, evaluated at the average inlet
water temperature measured during the
ith draw of the 24-hour simulated-use
test, (Tin,i), lb/gal (kg/L).
or, if the mass of water entering the water
heater is measured,
Mdel,i = Min,i
Where:
Min,i = mass of water entering the water
heater during draw ith draw of the 24hour simulated-use test, lb (kg).
6.3.3 Recovery Efficiency. The recovery
efficiency for gas, oil, and heat pump water
heaters with a rated storage volume greater
than or equal to 2 gallons, hr, is computed as:
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ER21JN23.020</GPH>
Otherwise, kV = 1.
Where:
T0= the mean tank temperature at the
beginning of the 24-hour simulated-use
test, °F(°C).
Tdel,1= the average outlet water temperature
during the first draw of the 24-hour
simulated-use test, °F(°C).
r(T0) = the density of the stored hot water
evaluated at the mean tank temperature
at the beginning of the 24-hour
simulated-use test (T0), lb/gal (kg/L).
Cp(T0) = the specific heat of the stored hot
water, evaluated at T0, Btu/(lb·°F) (kJ/
(kg·°C)).
Tmax,1 = the maximum measured mean tank
temperature after cut-out following the
first draw of the 24-hour simulated-use
test, °F(°C).
Tdel,2= the average outlet water temperature
during the second draw of the 24-hour
simulated-use test, °F(°C).
r(Tmax,1) = the density of the stored hot water
evaluated at the maximum measured
mean tank temperature after cut-out
following the first draw of the 24-hour
simulated-use test (Tmax,1), lb/gal (kg/L).
ER21JN23.019</GPH>
(if Tmax,1 > (Tdel,2 + 2.8 °C) and Tmax,1 ≥ 54.4
°C),
ER21JN23.018</GPH>
If Tmax,1 > (Tdel,2 + 5 °F) and Tmax,1 ≥ 130 °F,
ER21JN23.017</GPH>
If the first recovery period does not extend
into the second draw of the 24-hour
simulated use test, and
ER21JN23.016</GPH>
lotter on DSK11XQN23PROD with RULES2
Where:
Min,10m = the mass of water entering the water
heater during the maximum GPM (L/
min) rating test, lb (kg).
6.3 Computations for Water Heaters with
a Rated Storage Volume Greater Than or
Equal to 2 Gallons and Circulating Water
Heaters.
6.3.1 Storage Tank Capacity. The storage
tank capacity, Vst, is computed as follows:
Where:
Vst = the storage capacity of the water heater,
or, for circulating water heaters, the
storage capacity of the separate storage
tank used in accordance with section
4.10, gal (L).
Wf = the weight of the storage tank when
completely filled with water, lb (kg).
Wt = the (tare) weight of the storage tank
when completely empty, lb (kg).
r = the density of water used to fill the tank
measured at the temperature of the
water, lb/gal (kg/L).
6.3.1.1 Effective Storage Volume. The
effective storage tank capacity, Veff, is
computed as follows:
For water heaters requiring a separate
storage tank, Veff is the storage tank capacity
of the separate storage tank as determined per
section 6.3.1.
For all other water heaters:
Veff = kVVst
Where:
Vst = as defined in section 6.3.1 and
kV = a dimensionless volume scaling factor
determined as follows:
If the first recovery period extends into the
second draw of the 24-hour simulated use
test, and
If T0 > (Tdel,1 + 5 °F) and T0 ≥ 130 °F,
(if T0 > (Tdel,1 + 2.8 °C) and T0 ≥ 54.4 °C),
ER21JN23.015</GPH>
water temperature of the maximum GPM
(L/min) rating test (Tdel), lb/gal (kg/L).
or, if the mass of water entering the water
heater is measured,
40485
immersed heating elements, is assumed to be
98 percent.
6.3.4 Hourly Standby Losses. The energy
consumed as part of the standby loss test of
the 24-hour simulated-use test, Qstby, is
computed as:
Qstby = Qsu,f ¥ Qsu,o
Where:
Qsu,0 = cumulative energy consumption,
including all fossil fuel and electrical
energy use, of the water heater from the
start of the 24-hour simulated-use test to
the start of the standby period as
determined in section 5.4.2 of this
appendix, Btu (kJ).
Qsu,f = cumulative energy consumption,
including all fossil fuel and electrical
energy use, of the water heater from the
start of the 24-hour simulated-use test to
the end of the standby period as
determined in section 5.4.2 of this
appendix, Btu (kJ).
The hourly standby energy losses are
computed as:
Where:
Qhr = the hourly standby energy losses of the
water heater, Btu/h (kJ/h).
Vst = as defined in section 6.3.1 of this
appendix.
r = density of the stored hot water, evaluated
at (Tsu,f + Tsu,0)/2, lb/gal (kg/L).
Cp = specific heat of the stored water,
evaluated at (Tsu,f + Tsu,0)/2, Btu/(lb·°F),
(kJ/(kg·K)).
Tsu,f = the mean tank temperature measured
at the end of the standby period as
determined in section 5.4.2 of this
appendix, °F (°C).
Tsu,0 = the maximum mean tank temperature
measured at the beginning of the standby
period as determined in section 5.4.2 of
this appendix, °F (°C).
hr = as defined in section 6.3.3 of this
appendix.
tstby,1 = elapsed time between the start and
end of the standby period as determined
in section 5.4.2 of this appendix, h.
The standby heat loss coefficient for the
tank is computed as:
Where:
UA = standby heat loss coefficient of the
storage tank, Btu/(h· °F), (kJ/(h· °C).
Tt,stby,1 = overall average mean tank
temperature between the start and end of
the standby period as determined in
section 5.4.2 of this appendix, °F (°C).
Ta,stby,1 = overall average ambient temperature
between the start and end of the standby
period as determined in section 5.4.2 of
this appendix, °F (°C).
6.3.5 Daily Water Heating Energy
Consumption. The total energy used by
the water heater during the 24-hour
simulated-use test (Q) is as measured in
section 5.4.2 of this appendix, or,
Q = Qf + Qe = total energy used by the water
heater during the 24-hour simulated-use
test, including auxiliary energy such as
pilot lights, pumps, fans, etc., Btu (kJ).
Qf = total fossil fuel energy used by the water
heater during the 24-hour simulated-use
test, Btu (kJ).
Qe = total electrical energy used during the
24-hour simulated-use test, Btu (kJ).
(Electrical energy shall be converted to
thermal energy using the following
conversion: 1kWh = 3412 Btu.)
The daily water heating energy
consumption, Qd, is computed as:
Vst = as defined in section 6.3.1 of this
appendix.
r = density of the stored hot water, evaluated
at (T24 + T0)/2, lb/gal (kg/L).
Cp = specific heat of the stored water,
evaluated at (T24 + T0)/2, Btu/(lb·°F), (kJ/
(kg·K)).
T24 = mean tank temperature at the end of the
24-hour simulated-use test as determined
in section 5.4.2 of this appendix, °F (°C).
T0 = mean tank temperature recorded at the
beginning of the 24-hour simulated-use
test as determined in section 5.4.2 of this
appendix, °F (°C).
hr = as defined in section 6.3.3 of this
appendix.
6.3.6 Adjusted Daily Water Heating Energy
Consumption. The adjusted daily water
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ER21JN23.023</GPH>
Nr = number of draws from the start of the
24-hour simulated-use test to the end to
the first recovery period as described in
section 5.4.2.
Mdel,i = mass of water removed as calculated
in section 6.3.2 of this appendix during
the ith draw of the first recovery period
as described in section 5.4.2, lb (kg).
Cpi = specific heat of the withdrawn water
during the ith draw of the first recovery
period as described in section 5.4.2,
evaluated at (Tdel,i + Tin,i)/2, Btu/(lb· °F)
(kJ/(kg· °C)).
Tdel,i = average water outlet temperature
measured during the ith draw of the first
recovery period as described in section
5.4.2, °F (°C).
Tin,i = average water inlet temperature
measured during the ith draw of the first
recovery period as described in section
5.4.2, °F (°C).
The recovery efficiency for electric water
heaters with immersed heating elements, not
including heat pump water heaters with
ER21JN23.022</GPH>
Where:
Vst = as defined in section 6.3.1 of this
appendix.
r1 = density of stored hot water evaluated at
(Tmax,1 + T0)/2, lb/gal (kg/L).
Cp1 = specific heat of the stored hot water,
evaluated at (Tmax,1 + T0)/2, Btu/(lb·°F)
(kJ/(kg·°C).
Tmax,1 = maximum mean tank temperature
recorded after the first recovery period as
defined in section 5.4.2 of this appendix,
°F (°C).
T0 = mean tank temperature recorded at the
beginning of the 24-hour simulated-use
test as determined in section 5.4.2 of this
appendix, °F (°C).
Qr = the total energy used by the water heater
during the first recovery period as
defined in section 5.4.2 of this appendix,
including auxiliary energy such as pilot
lights, pumps, fans, etc., Btu (kJ).
(Electrical auxiliary energy shall be
converted to thermal energy using the
following conversion: 1 kWh = 3412
Btu).
ER21JN23.024</GPH>
Federal Register / Vol. 88, No. 118 / Wednesday, June 21, 2023 / Rules and Regulations
ER21JN23.021</GPH>
lotter on DSK11XQN23PROD with RULES2
40486
Federal Register / Vol. 88, No. 118 / Wednesday, June 21, 2023 / Rules and Regulations
40487
heating energy consumption, Qda, takes
into account that the ambient
temperature may differ from the nominal
value of 67.5 °F (19.7 °C) due to the
allowable variation in surrounding
ambient temperature of 65 °F (18.3 °C) to
70 °C (21.1 °C). The adjusted daily water
heating energy consumption is computed
as:
Qda = Qd ¥ (67.5°C ¥ Ta,stby,2) UA tstby,2
or,
Qda = Qd ¥ (19.7°C ¥ Ta,stby,2) UA tstby,2
Where:
Qda = the adjusted daily water heating energy
consumption, Btu (kJ).
Qd = as defined in section 6.3.4 of this
appendix.
Ta,stby,2 = the average ambient temperature
during the total standby portion, tstby,2, of
the 24-hour simulated-use test, °F (°C).
UA = as defined in section 6.3.4 of this
appendix.
tstby,2 = the number of hours during the 24hour simulated-use test when water is
not being withdrawn from the water
heater.
A modification is also needed to take into
account that the temperature difference
between the outlet water temperature and
supply water temperature may not be
equivalent to the nominal value of 67 °F
(125 °F–58 °F) or 37.3 °C (51.7 °C–14.4 °C).
The following equations adjust the
experimental data to a nominal 67 °F (37.3
°C) temperature rise.
The energy used to heat water, Btu/day (kJ/
day), may be computed as:
Where:
N = total number of draws in the 24-hour
simulated-use test.
Mdel,i = the mass of water removed during the
ith draw (i = 1 to N) as calculated in
section 6.3.2 of this appendix, lb (kg).
Cpi = the specific heat of the water withdrawn
during the ith draw of the 24-hour
simulated-use test, evaluated at (Tdel,i +
Tin,i)/2, Btu/(lb· °F) (kJ/(kg·°C)).
Tdel,i = the average water outlet temperature
measured during the ith draw (i = 1 to
N), °F (°C).
Tin,i = the average water inlet temperature
measured during the ith draw (i = 1 to
N), °F (°C).
hr = as defined in section 6.3.3 of this
appendix.
The energy required to heat the same
quantity of water over a 67 °F (37.3 °C)
temperature rise, Btu/day (kJ/day), is:
The difference between these two values is:
QHWD = QHW,67.°F ¥ QHW
or,
QHWD = QHW,37.3°C ¥ QHW
This difference (QHWD) must be added to
the adjusted daily water heating energy
consumption value. Thus, the daily energy
consumption value, which takes into account
that the ambient temperature may not be
67.5 °F (19.7 °C) and that the temperature rise
across the storage tank may not be 67 °F (37.3
°C) is:
Qdm = Qda ¥ QHWD
6.3.7 Estimated Mean Tank Temperature
for Water Heaters with Rated Storage
Volumes Greater Than or Equal to 2 Gallons.
If testing is conducted in accordance with
section 5.4.2.2 of this appendix, calculate the
mean tank temperature immediately prior to
the internal tank temperature determination
draw using the following equation:
Where:
Tst = the estimated average internal storage
tank temperature, °F (°C).
Tp = the average of the inlet and the outlet
water temperatures at the end of the
period defined by tp, °F (°C).
vout,p = the average flow rate during the
period, gal/min (L/min).
Vst = the rated storage volume of the water
heater, gal (L).
tp = the number of minutes in the duration
of the period, determined by the length
of time taken for the outlet water
temperature to be within 2 °F of the inlet
water temperature for 15 consecutive
seconds and including the 15-second
stabilization period.
Tin,p = the average of the inlet water
temperatures during the period, °F (°C).
Tout,p = the average of the outlet water
temperatures during the period, °F (°C).
6.3.8 Uniform Energy Factor. The
uniform energy factor, UEF, is computed as:
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ER21JN23.028</GPH>
ER21JN23.027</GPH>
ER21JN23.026</GPH>
ER21JN23.025</GPH>
lotter on DSK11XQN23PROD with RULES2
or,
58 °F)/2 = 91.5 °F ((51.7 °C + 14.4 °C)/2
= 33 °C), Btu/(lb·°F) (kJ/(kg·°C)).
6.3.9 Annual Energy Consumption. The
annual energy consumption for water heaters
with rated storage volumes greater than or
equal to 2 gallons is computed as:
Where:
UEF = the uniform energy factor as computed
in accordance with section 6.3.88 of this
appendix.
365 = the number of days in a year.
V = the volume of hot water drawn during
the applicable draw pattern, gallons.
= 10 for the very-small-usage draw pattern.
= 38 for the low-usage draw pattern.
= 55 for the medium-usage draw pattern.
= 84 for high-usage draw pattern.
r = 8.24 lb/gallon, the density of water at
125 °F.
Cp = 1.00 Btu/(lb °F), the specific heat of
water at 91.5 °F.
67 = the nominal temperature difference
between inlet and outlet water
6.3.10 Annual Electrical Energy
Consumption. The annual electrical energy
consumption in kilowatt-hours for water
heaters with rated storage volumes greater
than or equal to 2 gallons, Eannual,e, is
computed as:
Where:
Eannual = the annual energy consumption as
determined in accordance with section
6.3.99 of this appendix, Btu (kJ).
Qe = the daily electrical energy consumption
as defined in section 6.3.5 of this
appendix, Btu (kJ).
Q = total energy used by the water heater
during the 24-hour simulated-use test in
accordance with section 6.3.5 of this
appendix, Btu (kJ).
3412 = conversion factor from Btu to kWh.
6.3.11 Annual Fossil Fuel Energy
Consumption. The annual fossil fuel energy
consumption for water heaters with rated
storage volumes greater than or equal to 2
gallons, Eannual,f, is computed as:
Eannual,f = Eannual¥(Eannual,e * 3412)
Where:
Eannual = the annual energy consumption as
determined in accordance with section
6.3.9 of this appendix, Btu (kJ).
Eannual,e = the annual electrical energy
consumption as determined in
accordance with section 6.3.10 of this
appendix, kWh.
3412 = conversion factor from kWh to Btu.
6.4 Computations for Water Heaters with
a Rated Storage Volume Less Than 2 Gallons.
6.4.1 Mass of Water Removed
Calculate the mass of water removed using
the calculations in section 6.3.2 of this
appendix.
6.4.2 Recovery Efficiency. The recovery
efficiency, hr, is computed as:
Where:
M1 = mass of water removed during the first
draw of the 24-hour simulated-use test,
lb (kg).
Cp1 = specific heat of the withdrawn water
during the first draw of the 24-hour
simulated-use test, evaluated at (Tdel,1 +
Tin,1)/2, Btu/(lb·°F) (kJ/(kg·°C)).
Tdel,1 = average water outlet temperature
measured during the first draw of the 24hour simulated-use test, °F (°C).
Tin,1 = average water inlet temperature
measured during the first draw of the 24hour simulated-use test, °F (°C).
Qr = the total energy used by the water heater
during the first recovery period as
defined in section 5.4.3 of this appendix,
including auxiliary energy such as pilot
lights, pumps, fans, etc., Btu (kJ).
(Electrical auxiliary energy shall be
converted to thermal energy using the
following conversion: 1 kWh = 3412
Btu.)
6.4.3 Daily Water Heating Energy
Consumption. The daily water heating energy
consumption, Qd, is computed as:
Qd = Q
Where:
Q = Qf + Qe = the energy used by the water
heater during the 24-hour simulated-use
test.
Qf = total fossil fuel energy used by the water
heater during the 24-hour simulated-use
test, Btu (kJ).
Qe = total electrical energy used during the
24-hour simulated-use test, Btu (kJ).
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Mdel,i = the mass of water removed during the
ith draw (i = 1 to N) as calculated in
section 6.3.2 of this appendix, lb (kg).
Cpi = the specific heat of the water withdrawn
during the ith draw of the 24-hour
simulated-use test, evaluated at (125 °F +
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N = total number of draws in the 24-hour
simulated-use test.
Qdm = the modified daily water heating
energy consumption as computed in
accordance with section 6.3.6 of this
appendix, Btu (kJ).
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The following equations adjust the
experimental data to a nominal 67 °F
(37.3 °C) temperature rise.
The energy used to heat water may be
computed as:
Where:
N = total number of draws in the 24-hour
simulated-use test.
Mdel,i = the mass of water removed during the
ith draw (i = 1 to N) as calculated in
section 6.4.1 of this appendix, lb (kg).
Cpi = the specific heat of the water withdrawn
during the ith draw of the 24-hour
simulated-use test, evaluated at (Tdel,i +
Tin,i)/2, Btu/(lb·°F) (kJ/(kg·°C)).
Tdel,i = the average water outlet temperature
measured during the ith draw (i = 1 to
N), °F (°C).
Tin,i = the average water inlet temperature
measured during the ith draw (i = 1 to
N), °F (°C).
hr = as defined in section 6.4.2 of this
appendix.
The energy required to heat the same
quantity of water over a 67 °F (37.3 °C)
temperature rise is:
Where:
N = total number of draws in the 24-hour
simulated-use test.
Mdel,i = the mass of water removed during the
ith draw (i = 1 to N) as calculated in
section 6.4.1 of this appendix, lb (kg).
Cpi = the specific heat of the water withdrawn
during the ith draw of the 24-hour
simulated-use test, evaluated at (Tdel,i +
Tin,i)/2, Btu/(lb·°F) (kJ/(kg·°C)).
hr = as defined in section 6.4.2 of this
appendix.
The difference between these two values is:
QHWD = QHW,67°F¥QHW
or,
QHWD = QHW,37.3°C¥QHW
This difference (QHWD) must be added to
the daily water heating energy consumption
value. Thus, the daily energy consumption
value, which takes into account that the
temperature rise across the water heater may
not be 67 °F (37.3 °C), is:
Qdm = Qda + QHWD
6.4.4 Uniform Energy Factor. The
uniform energy factor, UEF, is computed as:
Where:
N = total number of draws in the 24-hour
simulated-use test.
Qdm = the modified daily water heating
energy consumption as computed in
accordance with section 6.4.3 of this
appendix, Btu (kJ).
Mdel,i = the mass of water removed during the
ith draw (i = 1 to N) as calculated in
section 6.4.1 of this appendix, lb (kg).
Cpi = the specific heat of the water withdrawn
during the ith draw of the 24-hour
simulated-use test, evaluated at (125 °F +
58 °F)/2 = 91.5 °F ((51.7 °C + 14.4 °C)/2 =
33.1 °C), Btu/(lb·°F) (kJ/(kg·°C)).
6.4.5 Annual Energy Consumption. The
annual energy consumption for water heaters
with rated storage volumes less than 2
gallons, Eannual, is computed as:
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A modification is needed to take into
account that the temperature difference
between the outlet water temperature and
supply water temperature may not be
equivalent to the nominal value of 67 °F
(125 °F¥58 °F) or 37.3 °C (51.7 °C¥14.4 °C).
ER21JN23.034</GPH>
(Electrical auxiliary energy shall be
converted to thermal energy using the
following conversion: 1 kWh = 3412
Btu.)
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Where:
UEF = the uniform energy factor as computed
in accordance with section 6.4.4 of this
appendix.
365 = the number of days in a year.
V = the volume of hot water drawn during
the applicable draw pattern, gallons.
= 10 for the very-small-usage draw pattern.
= 38 for the low-usage draw pattern.
= 55 for the medium-usage draw pattern.
= 84 for high-usage draw pattern.
r = 8.24 lb/gallon, the density of water at
125 °F.
Cp = 1.00 Btu/(lb °F), the specific heat of
water at 91.5 °F.
67 = the nominal temperature difference
between inlet and outlet water.
6.4.6 Annual Electrical Energy
Consumption. The annual electrical energy
consumption in kilowatt-hours for water
heaters with rated storage volumes less than
2 gallons, Eannual,e, is computed as:
Where:
Qe = the daily electrical energy consumption
as defined in section 6.4.3 of this
appendix, Btu (kJ).
Eannual = the annual energy consumption as
determined in accordance with section
6.4.5 of this appendix, Btu (kJ).
Q = total energy used by the water heater
during the 24-hour simulated-use test in
accordance with section 6.4.3 of this
appendix, Btu (kJ).
Qdm = the modified daily water heating
energy consumption as computed in
accordance with section 6.4.3 of this
appendix, Btu (kJ).
3412 = conversion factor from Btu to kWh.
6.4.7 Annual Fossil Fuel Energy
Consumption. The annual fossil fuel energy
consumption for water heaters with rated
storage volumes less than 2 gallons, Eannual,f,
is computed as:
Where:
Eannual = the annual energy consumption as
defined in section 6.4.5 of this appendix,
Btu (kJ).
Eannual,e = the annual electrical energy
consumption as defined in section 6.4.6
of this appendix, kWh.
3412 = conversion factor from kWh to Btu.
6.5 Energy Efficiency at Optional Test
Conditions. If testing is conducted at optional
test conditions in accordance with section
5.6 of this appendix, calculate the energy
efficiency at the test condition, EX, using the
formulas in sections 6.3 or 6.4 of this
appendix (as applicable), except substituting
the applicable ambient temperature and
supply water temperature used for testing (as
specified in section 2.8 of this appendix) for
the nominal ambient temperature and supply
water temperature conditions used in the
equations for determining UEF (i.e., 67.5 °F
and 58 °F).
7. Test Set-Up Diagrams
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Federal Register / Vol. 88, No. 118 / Wednesday, June 21, 2023 / Rules and Regulations
§ 431.102 Definitions concerning
commercial water heaters, hot water supply
boilers, unfired hot water storage tanks,
and commercial heat pump water heaters.
PART 431—ENERGY EFFICIENCY
PROGRAM FOR CERTAIN
COMMERCIAL AND INDUSTRIAL
EQUIPMENT
*
8. The authority citation for part 431
continues to read as follows:
■
Authority: 42 U.S.C. 6291–6317; 28 U.S.C.
2461 note.
9. Amend § 431.102 by revising the
definition for ‘‘Commercial heat pump
water heater (CHPWH)’’ to read as
follows:
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*
*
*
*
Commercial heat pump water heater
(CHPWH) means a water heater
(including all ancillary equipment such
as fans, blowers, pumps, storage tanks,
piping, and controls, as applicable) that
uses a refrigeration cycle, such as vapor
compression, to transfer heat from a
low-temperature source to a higher-
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temperature sink for the purpose of
heating potable water, and operates with
a current rating greater than 24 amperes
or a voltage greater than 250 volts. Such
equipment includes, but is not limited
to, air-source heat pump water heaters,
water-source heat pump water heaters,
and direct geo-exchange heat pump
water heaters.
*
*
*
*
*
[FR Doc. 2023–11429 Filed 6–20–23; 8:45 am]
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]]>Agencies
[Federal Register Volume 88, Number 118 (Wednesday, June 21, 2023)]
[Rules and Regulations]
[Pages 40406-40494]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-11429]
[[Page 40405]]
Vol. 88
Wednesday,
No. 118
June 21, 2023
Part II
Department of Energy
-----------------------------------------------------------------------
10 CFR Parts 429, 430, and 431
Energy Conservation Program: Test Procedure for Consumer Water Heaters
and Residential-Duty Commercial Water Heaters; Final Rule
Federal Register / Vol. 88, No. 118 / Wednesday, June 21, 2023 /
Rules and Regulations
[[Page 40406]]
-----------------------------------------------------------------------
DEPARTMENT OF ENERGY
10 CFR Parts 429, 430, and 431
[EERE-2019-BT-TP-0032]
RIN 1904-AE77
Energy Conservation Program: Test Procedure for Consumer Water
Heaters and Residential-Duty Commercial Water Heaters
AGENCY: Office of Energy Efficiency and Renewable Energy, Department of
Energy.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: This final rule incorporates by reference the latest version
of the industry testing standard for consumer water heaters and
residential-duty commercial water heaters and adopts relevant portions
of those standards into the Federal test procedure. In this final rule,
the U.S. Department of Energy (DOE) is also expanding the scope of
coverage of the test procedure to apply to certain consumer water
heater designs (including circulating water heaters and low-temperature
water heaters), adding definitions for certain specialty water heaters,
updating test conditions and tolerance requirements to reduce burden,
clarifying test set-up and installation methods, addressing the test
conduct for products which can store water at temperatures above the
delivery setpoint, establishing an effective volume calculation, and
extending untested provisions to electric instantaneous water heaters.
DATES: The effective date of this rule is July 21, 2023. The final rule
changes will be mandatory for consumer water heater testing starting
December 18, 2023 and for residential-duty commercial water heater
testing starting June 17, 2024. The incorporation by reference of
certain material listed in this rule is approved by the Director of the
Federal Register on July 21, 2023.
ADDRESSES: The docket, which includes Federal Register notices, public
meeting attendee lists and transcripts, comments, and other supporting
documents/materials, is available for review at www.regulations.gov.
All documents in the docket are listed in the www.regulations.gov
index. However, not all documents listed in the index may be publicly
available, such as those containing information that is exempt from
public disclosure.
A link to the docket web page can be found at: www.regulations.gov/docket/EERE-2019-BT-TP-0032. The docket web page contains instructions
on how to access all documents, including public comments, in the
docket.
For further information on how to review the docket, contact the
Appliance and Equipment Standards Program staff at (202) 287-1445 or by
email: [email protected].
FOR FURTHER INFORMATION CONTACT:
Ms. Julia Hegarty, U.S. Department of Energy, Office of Energy
Efficiency and Renewable Energy, Building Technologies Office, EE-5B,
1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone:
(202) 597-6737. Email: [email protected].
Mr. Eric Stas, U.S. Department of Energy, Office of the General
Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC 20585-0121.
Telephone: (202) 586-5827. Email: [email protected].
SUPPLEMENTARY INFORMATION: DOE incorporates by reference the following
industry standards into part 430:
ANSI/ASHRAE Standard 41.1-2020, ``Standard Methods for Temperature
Measurement,'' ANSI-approved June 30, 2020 (``ASHRAE 41.1-2020'').
ANSI/ASHRAE Standard 41.6-2014, ``Standard Method for Humidity
Measurement,'' ANSI-approved July 3, 2014 (``ASHRAE 41.6-2014'').
ANSI/ASHRAE Standard 118.2-2022, ``Method of Testing for Rating
Residential Water Heaters and Residential-Duty Commercial Water
Heaters,'' ANSI-approved March 1, 2022 (``ASHRAE 118.2-2022'').
Copies of ASHRAE 41.1-2020, ASHRAE 41.6-2014, and ASHRAE 118.2-2022
can be obtained from the American Society of Heating, Refrigerating,
and Air-Conditioning Engineers, Inc., (ASHRAE), 180 Technology Parkway
NW, Peachtree Corners, GA 30092, (800) 527-4723 or (404) 636-8400, or
online at: www.ashrae.org.
ASTM D2156-09 (Reapproved 2018) ``Standard Test Method for Smoke
Density in Flue Gases from Burning Distillate Fuels,'' approved October
1, 2018 (``ASTM D2156-09 (RA 2018)'').
ASTM E97-82 (Reapproved 1987) ``Standard Test Methods for
Directional Reflectance Factor, 45-Deg 0-Deg, of Opaque Specimens by
Broad-Band Filter Reflectometry,'' approved October 29, 1982 and
withdrawn 1991 (``ASTM E97-1987 (W1991)'').
Copies of ASTM D2156-09 (RA 2018) can be obtained from ASTM
International (ASTM), 100 Barr Harbor Drive, P.O. Box C700, West
Conshohocken, PA 19428-2959 or online at: www.astm.org.
Copies of ASTM E97-1987 (W1991) are reasonably available from
standards resellers including GlobalSpec's Engineering 360 (https://standards.globalspec.com/std/3801495/astm-e97-82-1987) and IHS Markit
(https://.global.ihs.com/
doc_detail.cfm?document_name=ASTM%20E97&item_s_key=00020483).
See section IV.N of this document for a further discussion of these
industry standards.
Table of Contents
I. Authority and Background
A. Authority
B. Background
II. Synopsis of the Final Rule
III. Discussion
A. Scope of Applicability and Definitions
1. Demand-Response Water Heaters
2. Heat Pump Water Heaters
3. Residential-Duty Commercial Water Heaters
4. Specialty Water Heaters
B. Updates to Industry Standards
1. ASHRAE 41.1-2020
2. ASHRAE 118.2-2022
C. Test Conditions and Tolerances
1. Supply Water Temperature Measurements
2. Gas Pressure
3. Input Rate
4. Ambient Test Condition Tolerances
5. Electrical Supply Voltage Tolerances
6. Flow Rate Tolerances
7. Optional Test Conditions for Heat Pump Water Heaters
D. Test Set-Up and Installation
1. Split-System Heat Pump Water Heaters
2. Mixing Valves
3. Flow Meter Location
4. Separate Storage Tanks
E. Test Conduct
1. High Temperature Testing
2. Very Small Draw Pattern Flow Rate
3. Low-Temperature Water Heaters
4. Delivery Temperature for Flow-Activated Water Heaters
5. Heat Pump Water Heaters
6. Draw Pattern for Commercial Applications
7. Method for Determining Internal Tank Temperature for Certain
Water Heaters
8. Alternate Order 24-Hour Simulated-Use Test
F. Computations
1. Mass Calculations
2. Effective Storage Volume
G. Untested Provisions (Alternative Efficiency Determination
Methods)
1. Representations of First-Hour Ratings for Untested Basic
Models
2. Alternative Rating Method for Electric Instantaneous Water
Heaters
H. Corrections and Clarifications
1. Flow-Activated Terminology
2. Second Identical 24-Hour Simulated-Use Test
3. Connected Products
4. Heating Value of Gas
I. Effective and Compliance Dates
J. Test Procedure Costs
1. Separate Storage Tanks
2. Method for Determining Internal Tank Temperature for Certain
Water Heaters
[[Page 40407]]
3. High Temperature Testing
4. Additional Amendments
IV. Procedural Issues and Regulatory Review
A. Review Under Executive Orders 12866, 13563, and 14094
B. Review Under the Regulatory Flexibility Act
C. Review Under the Paperwork Reduction Act of 1995
D. Review Under the National Environmental Policy Act of 1969
E. Review Under Executive Order 13132
F. Review Under Executive Order 12988
G. Review Under the Unfunded Mandates Reform Act of 1995
H. Review Under the Treasury and General Government
Appropriations Act, 1999
I. Review Under Executive Order 12630
J. Review Under Treasury and General Government Appropriations
Act, 2001
K. Review Under Executive Order 13211
L. Review Under Section 32 of the Federal Energy Administration
Act of 1974
M. Congressional Notification
N. Description of Materials Incorporated by Reference
V. Approval of the Office of the Secretary
I. Authority and Background
Consumer water heaters are included in the list of ``covered
products'' for which DOE is authorized to establish and amend energy
conservation standards and test procedures. (42 U.S.C. 6292(a)(4))
DOE's energy conservation standards and test procedures for consumer
water heaters are currently prescribed respectively at title 10 of the
Code of Federal Regulations (CFR), part 430, section 32(d), and 10 CFR
part 430, subpart B, appendix E ((appendix E), Uniform Test Method for
Measuring the Energy Consumption of Water Heaters. Residential-duty
commercial water heaters, for which DOE is also authorized to establish
and amend energy conservation standards and test procedures (42 U.S.C.
6311(1)(K)), must also be tested according to appendix E. 10 CFR
431.106(b)(1) (See 42 U.S.C. 6295(e)(5)(H)). DOE's energy conservation
standards for residential-duty commercial water heaters are currently
prescribed at 10 CFR 431.110(b)(1). The following sections discuss
DOE's authority to establish and amend test procedures for consumer
water heaters and residential-duty commercial water heaters, as well as
relevant background information regarding DOE's consideration of test
procedures for these products and equipment.
A. Authority
The Energy Policy and Conservation Act, as amended (EPCA),\1\
authorizes DOE to regulate the energy efficiency of a number of
consumer products and certain industrial equipment. (42 U.S.C. 6291-
6317, as codified) Title III, Part B \2\ of EPCA established the Energy
Conservation Program for Consumer Products Other Than Automobiles,
which sets forth a variety of provisions designed to improve energy
efficiency. (42 U.S.C. 6291-6309, as codified) These products include
consumer water heaters, one of the subjects of this document. (42
U.S.C. 6292(a)(4)) Title III, Part C \3\ of EPCA, added by Public Law
95-619, Title IV, section 441(a), established the Energy Conservation
Program for Certain Industrial Equipment, which again sets forth a
variety of provisions designed to improve energy efficiency. (42 U.S.C.
6311-6317, as codified) This equipment includes residential-duty
commercial water heaters, which are also the subject of this document.
(42 U.S.C. 6311(1)(K))
---------------------------------------------------------------------------
\1\ All references to EPCA in this document refer to the statute
as amended through the Energy Act of 2020, Public Law 116-260 (Dec.
27, 2020), which reflect the last statutory amendments that impact
Parts A and A-1 of EPCA.
\2\ For editorial reasons, upon codification in the U.S. Code,
Part B was redesignated Part A.
\3\ For editorial reasons, upon codification in the U.S. Code,
Part C was redesignated Part A-1.
---------------------------------------------------------------------------
The energy conservation program under EPCA consists essentially of
four parts: (1) testing, (2) labeling, (3) Federal energy conservation
standards, and (4) certification and enforcement procedures. Relevant
provisions of EPCA specifically include definitions (42 U.S.C. 6291; 42
U.S.C. 6311), test procedures (42 U.S.C. 6293; 42 U.S.C. 6314),
labeling provisions (42 U.S.C. 6294; 42 U.S.C. 6315), energy
conservation standards (42 U.S.C. 6295; 42 U.S.C. 6313), and the
authority to require information and reports from manufacturers (42
U.S.C. 6296; 42 U.S.C. 6316).
The Federal testing requirements consist of test procedures that
manufacturers of covered products and commercial equipment must use as
the basis for: (1) certifying to DOE that their products/equipment
comply with the applicable energy conservation standards adopted
pursuant to EPCA (42 U.S.C. 6295(s); 42 U.S.C. 6296; 42 U.S.C. 6316(a)-
(b)), and (2) making other representations about the efficiency of
those products/equipment (42 U.S.C. 6293(c); 42 U.S.C. 6314(d)).
Similarly, DOE must use these test procedures to determine whether the
products comply with any relevant standards promulgated under EPCA. (42
U.S.C. 6295(s))
Federal energy efficiency requirements for covered products and
equipment established under EPCA generally supersede State laws and
regulations concerning energy conservation testing, labeling, and
standards. (42 U.S.C. 6297(a)-(c); 42 U.S.C. 6316(a)-(b)) DOE may,
however, grant waivers of Federal preemption in limited circumstances
for particular State laws or regulations, in accordance with the
procedures and other provisions of EPCA. (42 U.S.C. 6297(d); 42 U.S.C.
6316(a); 42 U.S.C. 6316(b)(2)(D))
Under 42 U.S.C. 6293, EPCA sets forth the criteria and procedures
DOE must follow when prescribing or amending test procedures for
covered products. Specifically, EPCA requires that any test procedures
prescribed or amended shall be reasonably designed to produce test
results which measure energy efficiency, energy use, or estimated
annual operating cost of a covered product during a representative
average use cycle or period of use and not be unduly burdensome to
conduct. (42 U.S.C. 6293(b)(3)) Under 42 U.S.C. 6314, the statute sets
forth the criteria and procedures DOE must follow when prescribing or
amending test procedures for covered equipment, reciting similar
requirements at 42 U.S.C. 6314(a)(2).
In addition, the Energy Independence and Security Act of 2007
amended EPCA to require that DOE amend its test procedures for all
covered consumer products to integrate measures of standby mode and off
mode energy consumption. (42 U.S.C. 6295(gg)(2)(A)) Standby mode and
off mode energy consumption must be incorporated into the overall
energy efficiency, energy consumption, or other energy descriptor for
each covered product, unless the current test procedure already
accounts for and incorporates the standby mode and off mode energy
consumption, or if such integration is technically infeasible. (42
U.S.C. 6295(gg)(2)(A)(i)-(ii)) If an integrated test procedure is
technically infeasible, DOE must prescribe separate standby mode and
off mode energy use test procedures for the covered product, if a
separate test is technically feasible. (42 U.S.C. 6295(gg)(2)(A)(ii)))
Any such amendment must consider the most current versions of the
International Electrotechnical Commission (IEC) Standard 62301 \4\ and
IEC Standard 62087,\5\ as applicable. (42 U.S.C. 6295(gg)(2)(A))
---------------------------------------------------------------------------
\4\ IEC 62301, Household electrical appliances--Measurement of
standby power (Edition 2.0, 2011-01).
\5\ IEC 62087, Audio, video and related equipment--Methods of
measurement for power consumption (Edition 1.0, Parts 1-6: 2015,
Part 7: 2018).
---------------------------------------------------------------------------
The American Energy Manufacturing Technical Corrections Act
(AEMTCA), Public Law 112-210, further amended
[[Page 40408]]
EPCA to require that DOE establish a uniform efficiency descriptor and
accompanying test methods to replace the energy factor (EF) metric for
covered consumer water heaters and the thermal efficiency (TE) and
standby loss (SL) metrics for commercial water-heating equipment \6\
within one year of the enactment of AEMTCA. (42 U.S.C. 6295(e)(5)(B)-
(C)) The uniform efficiency descriptor and accompanying test method
were required to apply, to the maximum extent practicable, to all
water-heating technologies in use at the time and to future water-
heating technologies, but could exclude specific categories of covered
water heaters that do not have residential uses, can be clearly
described, and are effectively rated using the TE and SL descriptors.
(42 U.S.C. 6295(e)(5)(F) and (H)) In addition, beginning one year after
the date of publication of DOE's final rule establishing the uniform
descriptor, the efficiency standards for covered water heaters were
required to be denominated according to the uniform efficiency
descriptor established in the final rule (42 U.S.C. 6295(e)(5)(D)); and
for affected covered water heaters tested prior to the effective date
of the test procedure final rule, DOE was required to develop a
mathematical factor for converting the measurement of their energy
efficiency from the EF, TE, and SL metrics to the new uniform energy
descriptor. (42 U.S.C. 6295(e)(5)(E)(i)-(ii))
---------------------------------------------------------------------------
\6\ The initial thermal efficiency and standby loss test
procedures for commercial water heating equipment (including
residential-duty commercial water heaters) were added to EPCA by the
Energy Policy Act of 1992 (EPACT 1992), Public Law 102-486, and
corresponded to those referenced in the ASHRAE and Illuminating
Engineering Society of North America (IESNA) Standard 90.1-1989
(i.e., ASHRAE Standard 90.1-1989). (42 U.S.C. 6314(a)(4)(A)) DOE
subsequently updated the commercial water heating equipment test
procedures on two separate occasions--once in a direct final rule
published on October 21, 2004, and again in a final rule published
on May 16, 2012. These rules incorporated by reference certain
sections of the latest versions of American National Standards
Institute (ANSI) Standard Z21.10.3, Gas Water Heaters, Volume III,
Storage Water Heaters with Input Ratings Above 75,000 Btu Per Hour,
Circulating and Instantaneous, available at the time (i.e., ANSI
Z21.10.3-1998 and ANSI Z21.10.3-2011, respectively). 69 FR 61974,
61983 (Oct. 21, 2004) and 77 FR 28928, 28996 (May 16, 2012).
---------------------------------------------------------------------------
EPCA also requires that, at least once every seven years, DOE
evaluate test procedures for each type of covered product and covered
equipment, including consumer water heaters and residential-duty
commercial water heaters, to determine whether amended test procedures
would more accurately or fully comply with the requirements for the
test procedures to not be unduly burdensome to conduct and be
reasonably designed to produce test results that reflect energy
efficiency, energy use, and estimated operating costs during a
representative average use cycle (or additionally, period of use for
consumer products). (42 U.S.C. 6293(b)(1)(A); 42 U.S.C. 6314(a)(1)(A))
If the Secretary determines, on her own behalf or in response to a
petition by any interested person, that a test procedure should be
prescribed or amended, the Secretary shall promptly publish in the
Federal Register proposed test procedures and afford interested persons
an opportunity to present oral and written data, views, and arguments
with respect to such procedures. (42 U.S.C. 6293(b)(2); 42 US.C.
6314(b)) The comment period on a proposed rule to amend a test
procedure shall be at least 60 days \7\ and may not exceed 270 days.
(42 U.S.C. 6293(b)(2)) In prescribing or amending a test procedure, the
Secretary shall take into account such information as the Secretary
determines relevant to such procedure, including technological
developments relating to energy use or energy efficiency of the type
(or class) of covered products involved. (42 U.S.C. 6293(b)(2)) If DOE
determines that test procedure revisions are not appropriate, DOE must
publish in the Federal Register its determination not to amend the test
procedures. (42 U.S.C. 6293(b)(1)(A)(ii); 42 U.S.C. 6314(a)(1)(A)(ii))
DOE is publishing this final rule in satisfaction of the 7-year review
requirement specified in EPCA. (42 U.S.C. 6293(b)(1)(A) and 42 U.S.C.
6314(a)(1)(A))
---------------------------------------------------------------------------
\7\ For covered equipment, if the Secretary determines that a
test procedure amendment is warranted, the Secretary must publish
proposed test procedures in the Federal Register and afford
interested persons an opportunity (of not less than 45 days'
duration) to present oral and written data, views, and arguments on
the proposed test procedure. (42 U.S.C. 6314(b))
---------------------------------------------------------------------------
B. Background
The following discussion provides a brief history of the current
rulemaking, which considers potential amendments to the test procedure
for consumer water heaters and residential-duty commercial water
heaters.\8\ On April 16, 2020, DOE published in the Federal Register a
request for information (April 2020 RFI) seeking comments on the
existing DOE test procedure for consumer water heaters and residential-
duty commercial water heaters. 85 FR 21104. The April 2020 RFI
discussed a draft version of the American National Standards Institute
(ANSI)/American Society of Heating, Refrigeration, and Air Conditioning
Engineers (ASHRAE) Standard 118.2, ``Method of Testing for Rating
Residential Water Heaters and Residential-Duty Commercial Water
Heaters,'' published in March 2019 (March 2019 ASHRAE Draft 118.2),
which is very similar to the existing DOE test procedure for consumer
water heaters and residential-duty commercial water heaters. 85 FR
21104, 21108-21110 (April 16, 2020).
---------------------------------------------------------------------------
\8\ For a more complete history of earlier rulemaking efforts to
develop the energy conservation standards and test procedure for
consumer water heaters and residential-duty commercial water
heaters, please consult the January 11, 2022 NOPR. See 87 FR 1554,
1556-1558.
---------------------------------------------------------------------------
In the April 2020 RFI, DOE requested comments, information, and
data about a number of issues, including: (1) differences between the
March 2019 ASHRAE Draft 118.2 and the existing DOE test procedure; (2)
test tolerances for supply water temperature, ambient temperature,
relative humidity, voltage, and gas pressure; (3) the location of the
instrumentation that measures water volume or mass; and (4) how to test
certain types of consumer water heaters that cannot be easily tested to
the existing DOE test procedure (i.e., recirculating gas-fired
instantaneous water heaters, water heaters that cannot deliver water at
125 degrees Fahrenheit ([deg]F) 5 [deg]F, and water heaters
with storage volumes greater than 2 gallons that cannot have their
internal tank temperatures measured). Id. at 85 FR 21109-21114.
DOE subsequently published in the Federal Register a notice of
proposed rulemaking on January 11, 2022 (January 2022 NOPR) in which
the Department proposed to update appendix E, and related sections of
the CFR, as follows:
(1) Incorporate by reference current versions of industry standards
referenced by the current and proposed DOE test procedures: ASHRAE
Standard 41.1,\9\ ASHRAE Standard 41.6,\10\ the pending update to
ASHRAE Standard 118.2 \11\ (contingent on it being substantively the
same as the draft which was under review), ASTM International (ASTM)
Standard D2156,\12\ and ASTM Standard E97.\13\
---------------------------------------------------------------------------
\9\ ASHRAE Standard 41.1-2020, ``Standard Methods for
Temperature Measurement,'' approved June 30, 2020.
\10\ ASHRAE Standard 41.6-2014, ``Standard Method for Humidity
Measurement,'' ANSI approved July 3, 2014.
\11\ ASHRAE Standard 118.2-2022, ``Method of Testing for Rating
Residential Water Heaters and Residential-Duty Commercial Water
Heaters,'' ANSI approved March 1, 2022.
\12\ ASTM Standard D2156-09 (RA 2018), ``Standard Test Method
for Smoke Density in Flue Gases from Burning Distillate Fuels,''
reapproved October 1, 2018.
\13\ ASTM Standard E97-1987 (W 1991), ``Standard Test Methods
for Directional Reflectance Factor, 45-Deg 0-Deg, of Opaque
Specimens by Broad-Band Filter Reflectometry,'' approved January
1987, withdrawn 1991. Referenced by ASTM Standard D2156-09 (RA
2018).
---------------------------------------------------------------------------
[[Page 40409]]
(2) Add definitions for ``circulating water heater,'' ``low
temperature water heater,'' and ``tabletop water heater.''
(3) Specify how a mixing valve should be installed when the water
heater is designed to operate with one.
(4) Modify flow rate requirements during the first-hour rating
(FHR) test for water heaters with a rated storage volume less than 20
gallons.
(5) Modify timing of the first measurement in each draw of the 24-
hour simulated-use test.
(6) Clarify the determination of the first recovery period.
(7) Clarify the mass of water to be used to calculate recovery
efficiency.
(8) Modify the terminology throughout appendix E to explicitly
state ``non-flow activated'' and ``flow-activated'' water heater, where
appropriate.
(9) Clarify the descriptions of defined measured values for the
standby period measurements.
(10) Modify the test condition specifications and tolerances,
including electric supply voltage tolerance, ambient temperature,
ambient dry-bulb temperature, ambient relative humidity, standard
temperature and pressure definition, gas supply pressure, and manifold
pressure.
(11) Add provisions to address gas-fired water heaters with
measured fuel input rates that deviate from the certified input rate.
(12) Clarify provisions for calculating the volume or mass
delivered.
(13) Add specifications for testing for the newly defined ``low
temperature water heaters.''
(14) Clarify testing requirements for the heat pump part of a
split-system heat pump water heater.
(15) Define the use of a separate unfired hot water storage tank
for testing water heaters designed to operate with a separately sold
hot water storage tank.
(16) Clarify that any connection to an external network or control
be disconnected during testing.
(17) Add procedures for estimating internal stored water
temperature for water heater designs in which the internal tank
temperature cannot be directly measured.
(18) Modify the provisions for untested water heater basic models
within 10 CFR 429.70(g) to include electric instantaneous water
heaters.
87 FR 1554, 1558.\14\
---------------------------------------------------------------------------
\14\ A correction was published in the Federal Register on
January 19, 2022, to properly reflect the date of the public meeting
to discuss the January 2022 NOPR. 87 FR 2731.
---------------------------------------------------------------------------
DOE held a public meeting related to the January 2022 NOPR on
January 27, 2022 (hereinafter, the NOPR public meeting).
On July 14, 2022, DOE published a supplemental notice of proposed
rulemaking in the Federal Register (July 2022 SNOPR), that proposed to
maintain the proposals from the January 2022 NOPR but with
modifications discussed in the July 2022 SNOPR. 87 FR 42270.
Specifically, the July 2022 SNOPR proposed to further update appendix E
and related sections of the CFR by:
(1) Additionally requiring that, for water heaters with rated
storage volume less than 2 gallons and a rated maximum gallons per
minute (Max GPM or maximum GPM) of less than 1 gallon per minute, the
flow rate tolerance shall be 25 percent of the rated Max
GPM.
(2) Allowing optional efficiency representations at alternative
test conditions for heat pump water heaters.
(3) Adding a definition for ``split-system heat pump water
heaters'' to distinguish these from circulating heat pump water heaters
(i.e., ``heat pump-only'' water heaters).
(4) Requiring gas-fired circulating water heaters to be tested
using an unfired hot water storage tank (UFHWST) with a storage volume
between 80 and 120 gallons and meets but does not exceed the minimum
energy conservation standards (based on R-value) required at 10 CFR
431.110(a), and that circulating heat pump water heaters be tested
using a 40-gallon electric resistance water heater at the minimum UEF
standard required at 10 CFR 430.32(d).
(5) Requiring that water heaters (with the exception of demand-
response water heaters) with user-selectable modes to ``overheat'' the
water stored in the tank to increase effective capacity be tested at
the highest internal tank temperature that can be achieved while
maintaining the outlet water temperature at 125 [deg]F 5
[deg]F. (If no such overheated mode exists, the unit is to be tested in
a default mode.)
(6) Defining ``demand-response water heater'' based on the U.S.
Environmental Protection Agency (EPA) ENERGY STAR Product Specification
for Residential Water Heaters Version 5.0 (ENERGY STAR Water Heaters
Specification v5.0) \15\ definition for ``connected water heating
product,'' with the additional requirement that demand-response water
heaters cannot overheat as a result of user-initiated operation.
---------------------------------------------------------------------------
\15\ EPA published the ENERGY STAR Water Heater Specification
v5.0 on July 18, 2022. The ENERGY STAR Water Heater Specification
v5.0 is available online at: www.energystar.gov/products/spec/residential_water_heaters_specification_version_5_0_pd (Last
accessed on July 25, 2022).
---------------------------------------------------------------------------
(7) Establishing a metric and method for determining the effective
storage volume.
(8) Adopting a method of determining the internal storage tank
temperature for certain water heaters which cannot be directly measured
using draws at the beginning and end of the 24-hour simulated-use test.
87 FR 42270, 42273-42274 (July 14, 2022).
This final rule responds to comments received in response to the
January 2022 NOPR that were not addressed in the July 2022 SNOPR and
comments received in response to the July 2022 SNOPR. Table I.1
presents the list of commenters who provided written submissions and/or
oral statements at the NOPR public meeting which are addressed in this
final rule.
Table I.1--List of Commenters With Written Submissions Addressed in This Final Rule
----------------------------------------------------------------------------------------------------------------
Reference in this final Comment No. in the
Commenter(s) rule docket Commenter type
----------------------------------------------------------------------------------------------------------------
A.O. Smith Corporation............... A.O. Smith............. NOPR No. 37; Manufacturer.
Transcript*; SNOPR No.
51*.
Air Conditioning, Heating, and AHRI................... NOPR No. 40; Manufacturer Trade
Refrigeration Institute. Transcript; SNOPR No. Association.
55.
American Public Gas Association...... APGA................... NOPR No. 38............ Utility Trade
Association.
Appliance Standards Awareness Project ASAP................... Transcript............. Efficiency Advocacy
Organization.
Appliance Standards Awareness ASAP, ACEEE, and NCLC.. NOPR No. 34............ Efficiency Advocacy
Project, American Council for an Organizations.
Energy-Efficient Economy, National
Consumer Law Center (on behalf of
its low-income clients).
[[Page 40410]]
Appliance Standards Awareness ASAP, ACEEE, and NRDC.. SNOPR No. 54........... Efficiency Advocacy
Project, American Council for an Organizations.
Energy-Efficient Economy, Natural
Resources Defense Council.
Applied Energy Technology Company.... AET.................... NOPR No. 29............ Testing Laboratory.
Bradford White Corporation........... BWC.................... NOPR No. 33; SNOPR No. Manufacturer.
48.
Edison Electric Institute............ EEI.................... Transcript............. Utility Trade
Association.
GE Appliances........................ GEA.................... SNOPR No. 53........... Manufacturer.
Jim Lutz............................. Lutz................... NOPR No. 35............ Individual.
Nathan Dyson......................... Dyson.................. NOPR No. 28............ Individual.
New York State Energy Research and NYSERDA................ NOPR No. 32; SNOPR No. State Agency.
Development Authority. 50.
Northwest Energy Efficiency Alliance. NEEA................... NOPR No. 30; SNOPR No. Efficiency Advocacy
56. Organization.
Nyle Water Heating Systems, LLC...... Nyle................... SNOPR No. 57........... Manufacturer.
Pacific Gas and Electric Company, San CA IOUs................ NOPR No. 36; SNOPR No. Utilities.
Diego Gas and Electric, and Southern 52.
California Edison, collectively
referred to as the ``California
Investor-Owned Utilities''.
Rheem Manufacturing Company.......... Rheem.................. NOPR No. 31; Manufacturer.
Transcript; SNOPR No.
47.
SEA Groups, Ltd...................... SEA.................... NOPR No. 24............ Manufacturer.
Stone Mountain Technologies, Inc..... SMTI................... SNOPR No. 49........... Manufacturer.
----------------------------------------------------------------------------------------------------------------
* Note: The January 27, 2022 TP NOPR Pubic Meeting Transcript can be found in the docket for this rulemaking at
www.regulations.gov under entry number EERE-2019-BT-TP-0032-0027. Comments arising from the public meeting
will be cited as follows: (Commenter name, Jan. 27, 2022 Public Meeting Transcript, No. 27 at p. X).
A parenthetical reference at the end of a comment quotation or
paraphrase provides the location of the item in the public record.\16\
To the extent that interested parties have provided written comments
that are substantively similar to any oral comments provided during the
NOPR public meeting, DOE cites the written comments throughout this
final rule. Any oral comments provided during the webinar that are
substantively distinct from a submitter's written comments are
summarized and cited separately throughout this final rule.
---------------------------------------------------------------------------
\16\ The parenthetical reference provides a reference for
information located in the docket of DOE's rulemaking to develop
test procedures for consumer water heaters and residential-duty
commercial water heaters. (Docket No. EERE-2019-BT-TP-0032, which is
maintained at www.regulations.gov). The references are arranged as
follows: (commenter name, comment docket ID number, page of that
document).
---------------------------------------------------------------------------
APGA commented that DOE should adopt changes to its rulemaking
process as outlined in a report by National Academies of Sciences,
Engineering, and Medicine (NASEM) for both test procedures and
standards. (APGA, No. 38 at p. 2) In response, the Department notes
that the rulemaking process for test procedures of covered products and
equipment are outlined at appendix A to subpart C of 10 CFR part 430,
and DOE periodically examines and revises these provisions in separate
rulemaking proceedings.
Section II of this document provides a synopsis of this final rule,
and section III of this document discusses each amendment to the test
procedure for consumer water heaters and residential-duty commercial
water heaters in detail.
II. Synopsis of the Final Rule
In this final rule, DOE amends appendix E and related sections of
the CFR. In summary, the final rule:
1. Incorporates by reference current versions of industry
standards: ASHRAE 41.1, ASHRAE 41.6, ASHRAE 118.2, ASTM D2156, and ASTM
E97.
2. Adds definitions for ``circulating water heater, ``tabletop
water heater, and ``low-temperature water heater.
3. Harmonizes various aspects of the DOE test procedure with
industry test procedures ASHRAE 118.2-2022 and NEEA Advanced Water
Heating Specification v8.0.
4. Modifies the test condition specifications and tolerances,
including electric supply voltage tolerance, ambient conditions
(ambient dry-bulb temperature and ambient relative humidity), standard
temperature and pressure definition, gas supply pressure, manifold
pressure, inlet water temperature, and flow rate tolerances, and adds
optional test conditions for heat pump water heaters.
5. Specifies and clarifies methods for mixing valve installation
for affected water heaters, orifice modification, and calculation of
volume or mass delivered.
6. Defines the use of a separate unfired hot water storage tank or
separate electric storage water heater for testing water heaters
designed to operate with a separately sold tank.
7. Adds procedures for estimating internal stored water temperature
for water heater designs in which the internal tank temperature cannot
be directly measured.
8. Clarifies test procedures for water heaters with network
connection capabilities.
9. Clarifies test procedures for flow-activated water heaters and
water heaters that are not flow-activated by aligning terminology.
10. Includes additional testing provisions for electric resistance
water heaters undergoing optional high temperature testing.
11. Includes a calculation for determining the effective storage
volume of a water heater.
The adopted amendments are summarized in Table II.1 compared to the
test procedure provision prior to the amendment, as well as the reason
for the adopted change.
Table II.1--Summary of Changes in the Amended Test Procedure
------------------------------------------------------------------------
DOE test procedure prior to Amended test
amendment procedure Attribution
------------------------------------------------------------------------
References the 1986 (Reaffirmed References the Industry TP Update
2006) version of ASHRAE 41.1 updated 2020 to ASHRAE 41.1.
for methods for temperature version of ASHRAE
measurement. 41.1.
The 1982 version of ASHRAE 41.6 References the Industry TP Update
for methods for humidity 2014 version of to ASHRAE 41.6.
measurement is referenced ASHRAE 41.6,
within the 1986 version of which is
ASHRAE 41.1. referenced by
ASHRAE 41.1-2020.
[[Page 40411]]
References the 2009 version of References the Industry TP Update
ASTM D2156 for testing smoke version of ASTM to ASTM D2156.
density in flue gases from D2156 that was
burning distillate fuels. reaffirmed in
2018.
The 1987 version of ASTM E97 for References the Industry TP Update
testing directional reflectance 1987 version of to ASTM E97.
factor, 45-deg 0-deg, of opaque ASTM E97, which
specimens by broad-band filter is referenced by
reflectometry is referenced ASTM D2156-09 (RA
within ASTM D2156-09. 2018).
Does not define a ``circulating Adds a definition Allow for testing
water heater'' as used in 10 for ``circulating certain consumer
CFR 430.2. water heater'' to water heaters.
10 CFR 430.2.
Does not define a ``tabletop Adds a definition Reinstate
water heater'' as used as a for ``tabletop definition
product class distinction at 10 water heater'' to inadvertently
CFR 430.32(d). 10 CFR 430.2. removed by
previous final
rule.
Interprets the upper limit for Corrects the upper Make consistent
consumer electric heat pump limit for with statutory
water heaters to be 12 kW of consumer electric definition.
input, with ``commercial heat heat pump water
pump water heater'' defined at heaters to 24
10 CFR 431.102 as having rated amperes at 250
electric power input greater volts of input
than 12 kW. and amends the
definition for
``commercial heat
pump water
heater''
accordingly.
Does not address how to Specifies how a Method added by
configure a water heater for mixing valve DOE to improve
test when a mixing valve is should be repeatability.
required for proper operation. installed when
the water heater
is designed to
operate with one.
Requires the flow rate during Requires the flow Harmonization with
the FHR test to be 1.0 0.25 gpm (3.8 0.95 L/min) for water 1.5 2022.
heaters with a rated storage 0.25 gpm (5.7
volume less than 20 gallons. 0.95
L/min) for water
heaters with a
rated storage
volume less than
20 gallons.
Does not address the situation Clarifies that the Harmonization with
in which the first recovery first recovery industry TP
ends during a draw when testing period will ASHRAE 118.2-
to the 24-hour simulated-use extend to the end 2022.
test. of the draw in
which the first
recovery ended,
and that if a
second recovery
initiates prior
to the end of the
draw, that the
second recovery
is part of the
first recovery
period as well.
The recovery efficiency equation Clarifies that, Harmonization with
for storage-type water heaters for the industry TP
refers to the mass of water calculation of ASHRAE 118.2-
removed from the start of the recovery 2022.
test to the end of the first efficiency, the
recovery period. mass of water
removed during
the first
recovery period
includes water
removed during
all draws from
the start of the
test until the
end of the first
recovery period.
The procedures for the standby Clarifies the Harmonization with
period after the last draw of alternate industry TP
the 24-hour simulated-use test approach to ASHRAE 118.2-
allow for a recovery to occur determine the 2022.
at the end of the 8-hour energy consumed
standby period, which indicates during the 24-
that the power to the main hour simulated
burner, heating element, or use test if a
compressor is not disabled. standby period
occurs after the
final draw of the
test.
Appendix E uses the phrases Uses the terms Clarification.
``storage-type'' and ``non-flow
``instantaneous-type'' to refer activated'' and
to ``non-flow activated'' and ``flow-
``flow-activated'' water activated'' water
heaters, respectively. heater, where
appropriate.
The descriptions for Qsu,0, The descriptions Clarification.
Qsu,f, Tsu,0, Tsu,f, for Qsu,0, Qsu,f,
[tau]stby,1, Tt,stby,1, and Tsu,0, Tsu,f,
Ta,stby,1 only address when the [tau]stby,1,
standby period occurs between Tt,stby,1, and
draw clusters 1 and 2. Ta,stby,1 are
generalized to
refer to the
section where the
standby period is
determined.
Specifies that the first Specifies that the Method updated by
required measurement for each first required DOE to reduce
draw of the 24-hour simulated- measurement for burden.
use test is 5 seconds after the each draw of the
draw is initiated. 24-hour simulated-
use test is 15
seconds after the
draw is initiated.
Requires the electric supply Requires the Method updated by
voltage to be within 1 percent of the rated voltage to be burden.
voltage for the entire test. within 2 percent
of the rated
voltage beginning
5 seconds after
the start of a
recovery and
ending 5 seconds
before the end of
a recovery.
Requires maintaining ambient Requires Method updated by
temperature for non-heat pump maintaining the DOE to reduce
water heaters within a range of ambient burden.
67.5 [deg]F 2.5 temperature for
[deg]F. non-heat pump
water heaters
within a range of
67.5 [deg]F 5 [deg]F,
and with an
average of 67.5
[deg]F 2.5 [deg]F.
Requires maintaining the dry- Requires Method updated by
bulb temperature for heat pump maintaining the DOE to reduce
water heaters within a range of dry-bulb burden.
67.5 [deg]F 1 temperature for
[deg]F. heat pump water
heaters within a
range of 67.5
[deg]F 5 [deg]F,
and with an
average of 67.5
[deg]F 1 [deg]F
during recoveries
and an average of
67.5 [deg]F 2.5 [deg]F
when not
recovering.
Requires maintaining the Requires Method updated by
relative humidity for heat pump maintaining the DOE to reduce
water heaters within a range of relative humidity burden
50 percent 2 for heat pump
percent. water heaters
within a range of
50 percent 5 percent,
and at an average
of 50 percent
2
percent during
recoveries.
Requires that the heating value States that the Harmonization with
be corrected to a standard standard industry TP
temperature and pressure, but temperature is 60 ASHRAE 118.2-
does not state what temperature [deg]F (15.6 2022.
and pressure is standard or how [deg]C) and the
to correct the heating value to standard pressure
the standard temperature and is 30 inches of
pressure. mercury column
(101.6 kPa).
Provides a method
for converting
heating value
from the measured
to the standard
conditions via
incorporation by
reference of
ASHRAE 118.2-2022.
Requires that the manifold Clarifies that the Method updated by
pressure be within 10 percent of the tolerance applies burden.
manufacturer recommended value. only to water
heaters with a
pressure
regulator that
can be adjusted.
Requires that the
manifold pressure
be within the
greater of 10 percent
of the
manufacturer
recommended value
or 0.2 inches
water column.
Does not specify the input rate Specifies that the Method added by
at which the gas supply gas supply DOE to clarify
pressure tolerance is pressure enforcement test
determined. tolerance is to procedure.
be maintained
when operating at
the maximum input
rate.
Does not contain procedures for Adds provisions Method added by
modifying the orifice of a regarding the DOE to clarify
water heater that is not modification of enforcement test
operating at the manufacturer the orifice. procedure.
specified input rate.
Does not specify how to Specifies how to Method added by
calculate the mass removed from calculate the DOE to improve
the water heater when mass is mass of water repeatability.
calculated indirectly using indirectly using
density and volume measurements. density and
volume
measurements.
Does not accommodate testing of Adds a definition Allow for testing
``low-temperature water of ``low- certain consumer
heaters'' in appendix E. temperature water water heaters.
heater'' in 10
CFR 430.2 and
requires low
temperature water
heaters to be
tested to their
maximum possible
delivery
temperature in
appendix E.
[[Page 40412]]
Does not explicitly define the Explicitly states Method added by
test conditions required for that the heat DOE to improve
each part of a split-system pump part of a representativenes
heat pump water heater. split-system heat s and
pump water heater repeatability.
is tested at the
dry-bulb
temperature and
relative humidity
conditions
required for heat
pump water
heaters, and that
the storage tank
is tested at the
ambient
temperature and
relative humidity
conditions
required for non-
heat pump water
heaters.
Does not accommodate testing of Requires that gas- Allow for testing
water heaters that require a fired circulating certain consumer
separately-sold hot water water heaters be water heaters.
storage tank to properly tested using a
operate. UFHWST with a
storage volume
between 80 and
120 gallons and
that meets but
does not exceed
the minimum
energy
conservation
standards
required
according to 10
CFR 431.110(a),
and that heat
pump circulating
water heaters be
tested using a 40-
gallon electric
storage water
heater at the
minimum UEF
standard required
at 10 CFR
430.32(d).
Does not address water heaters Explicitly states Clarification.
with network connection that any
capabilities. connection to an
external network
or control be
disconnected
during testing.
Does not accommodate certain Establishes a Allow for testing
water heaters for which the method of certain consumer
mean tank temperature cannot be determining the water heaters.
directly measured. internal storage
tank temperature
using draws at
the beginning and
end of the 24-
hour simulated
use test.
10 CFR 429.70(g) does not allow Extends the AEDM allowed by
untested electric instantaneous untested DOE to reduce
water heaters to be certified, provisions within burden.
but does allow untested 10 CFR 429.70(g)
electric storage water heaters to include
to be certified. electric
instantaneous
water heaters.
Does not specify flow rate Specifies that Method added by
tolerance for water heaters flow rates for DOE to improve
with rated storage volume less all water heaters repeatability and
than 2 gallons. with rated reproducibility.
storage volume
less than 2
gallons must be
maintained within
a tolerance of
0.25
gallons per
minute.
Additionally
proposes that for
water heaters
with rated
storage volume
less than 2
gallons and a
rated Max GPM of
less than 1
gallon per
minute, the flow
rate tolerance
shall be 25 percent
of the rated Max
GPM.
Does not include optional Allows for Harmonization with
efficiency representations at optional industry TP NEEA
alternative test conditions for efficiency Advanced Water
heat pump water heaters. representations Heating
at alternative Specification
test conditions v8.0.
for heat pump
water heaters.
Does not include a definition Adds a definition Harmonization with
for ``split-system heat pump for ``split- industry TP NEEA
water heater.''. system heat pump Advanced Water
water heater'' to Heating
distinguish these Specification
from heat pump- v8.0.
only water
heaters.
Specifies that water heaters Provides a test Method added by
with multiple modes of method for DOE to improve
operation be tested in the electric representativenes
``default'' or other similarly resistance water s.
named mode. heaters subject
to high
temperature
testing (setting
the water heater
to the highest
storage tank
temperature and
using a mixing
valve to temper
the delivery
water to be
within 125 5 [deg]F).
Does not require
the use of this
type of testing
for any water
heaters, however,
until compliance
with amended
standards is
required.
Does not include any method to Establishes a Method added by
determine effective storage metric and method DOE which adopts
volume of storage-type water for determining a metric for
heaters or circulating water the effective additional
heaters. storage volume of consumer
storage-type information.
water heaters and
circulating water
heaters.
Does not include a definition Adopts a Harmonization with
for ``thermal break.''. definition for industry TP
``thermal break'' ASHRAE 118.2-
but does not 2022.
mandate the use
of this component
in test set-up.
------------------------------------------------------------------------
DOE has determined that the amendments described in section III and
adopted in this document will not alter the measured efficiency of
consumer water heaters and residential-duty commercial water heaters,
or require retesting or recertification solely as a result of DOE's
adoption of the amendments to the test procedures. Discussion of DOE's
actions are addressed in detail in section III of this document.
The effective date for the amended test procedures adopted in this
final rule is 30 days after publication of this document in the Federal
Register. Representations of energy use or energy efficiency must be
based on testing in accordance with the amended test procedures
beginning 180 days after the publication of this final rule for
consumer water heaters and 360 after the publication of this final rule
for residential-duty commercial water heaters.
III. Discussion
A. Scope of Applicability and Definitions
This document covers those products that meet the definition of
consumer ``water heaters,'' as defined in the statute at 42 U.S.C.
6291(27), as codified at 10 CFR 430.2. This document also covers
commercial water heating equipment with residential applications
((i.e., those water heaters which meet the definition of ``residential-
duty commercial water heater'' at 10 CFR 431.102).
In the context of covered consumer products, EPCA defines ``water
heater'' as a product which utilizes oil, gas, or electricity to heat
potable water for use outside the heater upon demand, including--
(a) Storage type units which heat and store water at a
thermostatically controlled temperature, including gas storage water
heaters with an input of 75,000 Btu per hour or less, oil storage water
heaters with an input of 105,000 Btu per hour or less, and electric
storage water heaters with an input of 12 kilowatts or less;
(b) Instantaneous type units which heat water but contain no more
than one gallon of water per 4,000 Btu per hour of input, including gas
instantaneous water heaters with an input of 200,000 Btu per hour or
less, oil instantaneous water heaters with an input of 210,000 Btu per
hour or less, and electric instantaneous water heaters with an input of
12 kilowatts or less; and
(c) Heat pump type units, with a maximum current rating of 24
amperes at a voltage no greater than 250 volts, which are products
designed to transfer thermal energy from one temperature level to a
higher temperature level for the purpose of heating water, including
all ancillary equipment such as fans, storage tanks, pumps, or controls
[[Page 40413]]
necessary for the device to perform its function.
(42 U.S.C. 6291(27); 10 CFR 430.2)
In addition, at 10 CFR 430.2, DOE defines several specific
categories of consumer water heaters, as follows:
(1) ``Electric instantaneous water heater'' means a water heater
that uses electricity as the energy source, has a nameplate input
rating of 12 kW or less, and contains no more than one gallon of water
per 4,000 Btu per hour of input.
(2) ``Electric storage water heater'' means a water heater that
uses electricity as the energy source, has a nameplate input rating of
12 kW or less, and contains more than one gallon of water per 4,000 Btu
per hour of input.
(3) ``Gas-fired instantaneous water heater'' means a water heater
that uses gas as the main energy source, has a nameplate input rating
less than 200,000 Btu/h, and contains no more than one gallon of water
per 4,000 Btu per hour of input.
(4) ``Gas-fired storage water heater'' means a water heater that
uses gas as the main energy source, has a nameplate input rating of
75,000 Btu/h or less, and contains more than one gallon of water per
4,000 Btu per hour of input.
(5) ``Grid-enabled water heater'' means an electric resistance
water heater that--
(a) Has a rated storage tank volume of more than 75 gallons;
(b) Is manufactured on or after April 16, 2015;
(c) Is equipped at the point of manufacture with an activation lock
and;
(d) Bears a permanent label applied by the manufacturer that--
(i) Is made of material not adversely affected by water;
(ii) Is attached by means of non-water-soluble adhesive; and
(iii) Advises purchasers and end-users of the intended and
appropriate use of the product with the following notice printed in
16.5 point Arial Narrow Bold font: ``IMPORTANT INFORMATION: This water
heater is intended only for use as part of an electric thermal storage
or demand response program. It will not provide adequate hot water
unless enrolled in such a program and activated by your utility company
or another program operator. Confirm the availability of a program in
your local area before purchasing or installing this product.''
(6) ``Oil-fired instantaneous water heater'' means a water heater
that uses oil as the main energy source, has a nameplate input rating
of 210,000 Btu/h or less, and contains no more than one gallon of water
per 4,000 Btu per hour of input.
(7) ``Oil-fired storage water heater'' means a water heater that
uses oil as the main energy source, has a nameplate input rating of
105,000 Btu/h or less, and contains more than one gallon of water per
4,000 Btu per hour of input.
The definition for ``grid-enabled water heater'' includes the term
``activation lock,'' which is defined to mean a control mechanism
(either by a physical device directly on the water heater or a control
system integrated into the water heater) that is locked by default and
contains a physical, software, or digital communication that must be
activated with an activation key to enable the product to operate at
its designed specifications and capabilities and without which the
activation of the product will provide not greater than 50 percent of
the rated first-hour delivery of hot water certified by the
manufacturer. 10 CFR 430.2. As specified in this definition, the
control mechanism must be physically incorporated into the water heater
or, if a control system, integrated into the water heater to qualify as
an activation lock. DOE is aware of certain State programs that
encourage water heaters to be equipped with communication ports that
allow for demand-response communication between the water heater and
the utility.\17\ DOE notes that presence of such a communication port,
in and of itself, would not qualify as an activation lock for the
purpose of classifying a water heater as a grid-enabled water heater.
Demand-response water heaters are discussed separately in section
III.A.1 of this final rule.
---------------------------------------------------------------------------
\17\ On May 7, 2019, the State of Washington signed House Bill
1444 which amended the Revised Code of Washington (RCW) (i.e., the
statutory code in the State of Washington), Title 19, Chapter 19.260
(RCW 19.260). On January 6, 2020, the State of Washington amended
the Washington Administrative Code (WAC) (i.e., the regulatory code
in the State of Washington), Title 194, Chapter 194-24 (WAC 194-24)
(Washington January 2020 Amendment) to align with RCW 19.260.
Similarly, the State of Oregon published a final rule (Oregon August
2020 final rule) on August 8, 2020, which amended the Oregon
Administrative Rules (OAR), Chapter 330, Division 92 (OAR-330-092).
The Washington House Bill 1444 and the Oregon August 2020 final rule
established a definition for electric storage water heater (RCW
19.260.020(14); OAR-330-092-0010(10)), an effective date of January
1, 2021 in Washington and January 1, 2022 in Oregon (RCW
19.260.080(1); OAR-330-092-0015(17)), a requirement that electric
storage water heaters must have a modular demand response
communications port compliant with the March 2018 version of the
ANSI/CTA-2045-A communication interface standard, or a standard
determined to be equivalent (RCW 19.260.080(1)(a)-(b); OAR-330-092-
0020(17)), and, in Oregon, must bear a label or marking on the
products stating either ``DR-ready: CTA-2045-A'' or ``DR-ready: CTA-
2045-A and [equivalent DR system protocol]'' (OAR-330-092-0045(17)).
---------------------------------------------------------------------------
Additionally, as discussed further in section III.A.3 of this
document, the appendix E test procedure also applies to residential-
duty commercial water heaters. (See 10 CFR 431.106(b)(1)) DOE defines
these equipment categories at 10 CFR 431.102 as any gas-fired storage,
oil-fired storage, or electric instantaneous commercial water heater
that meets the following conditions:
(1) For models requiring electricity, uses single-phase external
power supply;
(2) Is not designed to provide outlet hot water at temperatures
greater than 180 [deg]F; and
(3) Does not meet any of the following criteria:
------------------------------------------------------------------------
Water heater type Indicator of non-residential application
------------------------------------------------------------------------
Gas-fired Storage............. Rated input >105 kBtu/h; Rated storage
volume >120 gallons.
Oil-fired Storage............. Rated input >140 kBtu/h; Rated storage
volume >120 gallons.
Electric Instantaneous........ Rated input >58.6 kW; Rated storage
volume >2 gallons.
------------------------------------------------------------------------
In the January 2022 NOPR, DOE discussed definitions and the scope
of appendix E for heat pump water heaters (electric as well as gas-
fired), gas-fired instantaneous water heaters (specifically circulating
gas-fired water heaters), tabletop water heaters, and residential-duty
commercial water heaters. 87 FR 1554, 1560-1567 (Jan. 11, 2022).
Additionally, DOE proposed a new definition for ``demand-response water
heater'' in the July 2022 SNOPR. 87 FR 42270, 42280 (July 14, 2022).
BWC generally agreed with DOE's determinations regarding product
and equipment definitions and classifications. (BWC, No. 33 at p. 1)
AET generally commented that DOE's test procedures should be
appropriate for all consumer water heaters within the scope of
standards, especially for electric instantaneous water heaters. (AET,
No. 29 at pp. 11-12)
[[Page 40414]]
As discussed throughout this rulemaking, it is DOE's intention to
ensure that the appendix E test procedure amended by this final rule is
appropriate and applicable to all consumer water heaters and
residential-duty commercial water heaters. Sections III.A.1 through
III.A.4 of this document address specific issues related to scope and
definitions that either DOE requested comment on in the January 2022
NOPR or July 2022 SNOPR, or that were identified by commenters in
response to those documents.
1. Demand-Response Water Heaters
Storage-type water heaters that have ``connected'' capability,
often referred to as ``demand-response'' water heaters, can be remotely
activated and/or deactivated by signals from a utility company or
another program operator, and are able to serve as a thermal energy
storage device. DOE considered whether specific testing requirements
would be appropriate for demand-response water heaters (such as
requiring measurement of the energy consumed by connected features, or
providing a method for calculating the amount of thermal energy storage
available); however, DOE had tentatively determined that additional
test procedure provisions (such as the calculation of a thermal energy
storage metric) are premature and unnecessary to specify at this time
as the market continues to develop and evolve. DOE proposed only that a
provision be added to the test procedure to require that if a water
heater can connect to an external network or controller, that
communication shall be disabled during testing. 87 FR 1554, 1585-1586
(Jan. 11, 2022). Several stakeholders provided input on this tentative
determination.
NEEA encouraged DOE to adopt definitions and test methods for
``connectable'' water heaters in the test procedure. The commenter
pointed to the following existing and emerging standards as references:
Consumer Technology Association (CTA) Standard 2045 (ANSI/CTA-2045)/
EcoPort,\18\ U.S. Environmental Protection Agency (EPA) ENERGY STAR
connected device requirements, and AHRI 1430, Standard for Demand
Response for Electric Water Heaters.\19\ NEEA stated that definitions
of connectivity have already been adopted by the States of Washington,
Oregon, and California as part of their water heating appliance
standards. (NEEA, No. 30 at pp. 2-3) The CA IOUs recommended the
adoption of a definition for the communication capability for grid-
enabled water heaters that is consistent with the Connected Product
Criteria in the ENERGY STAR Product Specification for Residential Water
Heaters.\20\ The CA IOUs also recommended that DOE incorporate the
associated ENERGY STAR connected products test procedure into the
appendix E test procedure. (CA IOUs, No. 36 at pp. 2-3)
---------------------------------------------------------------------------
\18\ Available online at: shop.cta.tech/products/https-cdn-cta-
tech-cta-media-media-ansi-cta-2045-b-final-2022-pdf (Last accessed
on Sept. 17, 2022).
\19\ AHRI Standard 1430, ``Standard for Demand Response for
Electric Water Heaters,'' was published in December 2022. It is an
industry consensus standard developed by an AHRI Consensus Standards
Project Committee that includes definitions, test requirements,
operating and physical requirements, minimum data requirements for
published ratings, marking and nameplate, and data and conformance
conditions for demand-response electric water heaters. For more
information, see www.ahrinet.org/search-standards/ahri-1430-demand-flexible-electric-storage-water-heaters (Last accessed on Feb. 17,
2023).
\20\ According to version 5.0 of the ENERGY STAR Program
Requirements for Residential Water Heaters Eligibility Criteria, a
``connected water heater product (CWHP)'' includes the ENERGY STAR
certified water heater, integrated or separate communications
hardware, and additional hardware and software required to enable
connected functionality. ``Demand Response'' is also defined by that
source to mean changes in electric or gas usage by end-use customers
from their normal consumption patterns in response to changes in the
price of electricity or gas over time, or to incentive payments
designed to induce lower electricity or gas use at times of high
wholesale market prices or when system reliability is jeopardized.
Version 5.0 of the ENERGY STAR specification is available online at:
www.energystar.gov/products/spec/residential_water_heaters_specification_version_5_0_pd (Last
accessed on July 25, 2022).
---------------------------------------------------------------------------
In response, DOE considered these comments and also assessed the
operation of demand-response water heaters as grid thermal energy
storage devices using specific communication protocols in order to
determine how to distinguish these products from other water heaters
capable of storage tank overheating. On July 18, 2022, EPA published an
ENERGY STAR Version 5.0 Residential Water Heater Specification, which
included definitions for ``connected water heater product'' and
``demand response.'' These definitions included references to Consumer
Technology Association (CTA) Standard 2045 (ANSI/CTA-2045),\21\ a
design standard for a communications module that allows a water heater
to receive signals from a utility company (e.g., a curtailment
request). As indicated by NEEA and the CA IOUs, the presence of a CTA-
2045 port uniquely enables a water heater to be able to participate in
any demand-response program, and DOE has additionally determined that
products with these features are increasing in number.
---------------------------------------------------------------------------
\21\ See section 4.D.a of the ENERGY STAR Version 5.0
specification.
---------------------------------------------------------------------------
In the July 2022 SNOPR, DOE noted that certain new water heaters
were available on the market that are shipped from the point of
manufacture with a mixing valve installed and intentionally
``overheat'' \22\ the water to a stored temperature that is higher than
the delivery temperature setpoint to provide additional capacity.\23\
87 FR 42270, 42279-42280 (July 14, 2022). DOE proposed specific test
requirements for such products (see section III.E.1 of this document
for discussion). DOE also noted that water heaters with demand-response
capabilities may undergo utility-initiated overheating during certain
periods to store additional energy in the water heater during peak
demand periods, and tentatively determined that the test provisions
proposed for water heaters that overheat may not be appropriate for
demand-response water heaters that overheat. Id. To distinguish demand-
response water heaters from other types capable of overheating, DOE
proposed to define a ``demand-response water heater'' as follows:
---------------------------------------------------------------------------
\22\ The term ``overheating'' refers to raising the tank
temperature above the outlet water setpoint and does not denote
performance outside of the normal operating range of the water
heater.
\23\ While typical water heaters do not store water warmer than
the outlet temperature setpoint (which is, on average, 125 5 [deg]F), water heaters designed to increase energy storage
capacity may overheat the tank to temperatures such as 140-150
[deg]F and use a mixing valve to temper the outlet water down to the
setpoint condition. The energy storage capacity is proportional to
both the size of the tank and the temperature of the water within.
---------------------------------------------------------------------------
Demand-response water heater means a storage-type water heater
that--
1. Has integrated communications hardware and additional hardware
and software required to enable connected functionality with a utility
or third party, that dispatches signals with demand response
instructions and/or price signals to the product and receives messages
from the demand-response water heater;
2. Meets the communication and equipment standards for Consumer
Technology Association (CTA) Standard 2045-B (ANSI/CTA-2045-B); \24\
---------------------------------------------------------------------------
\24\ ANSI/CTA-2045-B, ``Modular Communications Interface for
Energy Management,'' published February 2021. (Available at:
shop.cta.tech/products/https-cdn-cta-tech-cta-media-media-ansi-cta-
2045-b-final-2022-pdf) (Last accessed Sept. 17, 2022).
---------------------------------------------------------------------------
3. Automatically heats the stored water above the delivery
temperature setpoint only in response to instructions received from a
utility or third party.
87 FR 42270, 42280 (July 14, 2022). DOE sought comment on this proposed
definition. Id.
[[Page 40415]]
In response to the July 2022 SNOPR, AHRI, A.O. Smith, BWC, and
Rheem recommended that DOE change its definition of ``demand-response
water heater'' to be consistent with ENERGY STAR and AHRI Standard
1430.\25\ (AHRI, No. 55 at p. 7; A.O. Smith, No. 51 at pp. 6-7; BWC,
No. 48 at p. 2; Rheem, No. 47 at p. 6) Specifically, AHRI and A.O.
Smith requested that DOE define ``demand-flexible water heater'' as
``an electric resistance storage water heater or heat pump water heater
with the capability to reduce, shed, shift, load up, and modulate
energy consumption in response to a command or instructions received
from a utility or third party.'' (AHRI, No. 55 at p. 7; A.O. Smith, No.
51 at pp. 6-7) BWC requested that DOE use the ENERGY STAR and AHRI
Standard 1430 definitions of ``demand-response'' to avoid manufacturer
burden and allow for easier future development of these products. (BWC,
No. 48 at p. 2) Rheem further recommended that DOE seek direct feedback
from EPA's ENERGY STAR program. (Rheem, No. 47 at p. 6)
---------------------------------------------------------------------------
\25\ AHRI Standard 1430-2022 (I-P), ``2022 Standard for Demand
Flexible Water Heaters,'' published December 2022. (Available at:
https://www.ahrinet.org/search-standards/ahri-1430-demand-flexible-electric-storage-water-heaters.) (Last accessed Feb. 17, 2023)
---------------------------------------------------------------------------
NYSERDA pointed out that DOE's proposed definition for ``demand-
response water heater,'' which states that it cannot overheat as a
result of user-initiated operation, is an additional requirement beyond
ENERGY STAR's definitions. Accordingly, NYSERDA urged DOE to define
``overheating test exempt water heaters'' so as to avoid creating
market confusion, and the commenter recommended that DOE consider the
power usage for connectedness as included in the ENERGY STAR water
heater specification, as it would allow utilities to plan more
effectively, encourage the additional load to be minimal, and inform
consumers regarding anticipated operating costs. (NYSERDA, No. 50 at p.
2)
NEEA indicated support for DOE's proposed definition of ``demand-
response water heater'' and the proposal for demand-response water
heaters to meet the communication and equipment standards for ANSI/CTA-
2045. (NEEA, No. 56 at pp. 2-3) AHRI, however, indicated that DOE's
definition would require compliance with the demand-response program
the water heater is enrolled in, whereas other, non-DOE definitions
allow consumers to opt out. (AHRI, No. 55 at p. 7) BWC and Rheem
requested that DOE remove the requirement to comply with CTA-2045.
(BWC, No. 48 at pp. 1-2, Rheem, No. 47 at p. 6) BWC stated that
requiring compliance with CTA-2045 may prevent manufacturers from
designing their products around separate and future protocols. (BWC,
No. 48 at pp. 1-2)
Rheem recommended that DOE's definition acknowledge the fact that
many water heaters with demand-response capability are currently
shipped without all necessary hardware to participate in a demand-
response program. Rheem also suggested that DOE's definition does not
cover most demand-response water heaters because it excludes water
heaters without the ability to heat water above the setpoint. (Rheem,
No. 47 at p. 6)
After reviewing these comments from stakeholders, DOE understands
that, for the purpose of demand-response programs, utilities and
manufacturers would benefit from a standardized definition of ``demand-
response water heater,'' specifically one that requires certain
communications protocols to be present in order to be compatible with
the demand-response signals from the utility or third-party.
Stakeholders have indicated that, in order to be deemed a ``demand-
response water heater,'' a product must demonstrate that it is capable
of executing the commands from the demand-response signals (i.e., pass
the verification tests in the ENERGY STAR Test Method to Validate
Demand Response or in AHRI Standard 1430). However, DOE proposed a more
limited definition for ``demand-response water heater'' in the July
2022 SNOPR, seeking only to describe the types of water heaters that
could temporarily increase the storage tank temperature as a means to
perform a load up \26\ such that this particular operation would not be
considered ``overheating'' in the appendix E test procedure (see 87 FR
42270, 42280 (July 14, 2022)). This led DOE to revisit its proposed
definition and to reassess its planned approach.
---------------------------------------------------------------------------
\26\ According to the ENERGY STAR Test Method to Validate Demand
Response v1.2, a connected water heating product is required to use
and/or store additional thermal energy that the device otherwise
would not have used/stored under normal operation in response to a
load up request. This allows the stored thermal energy to increase
within the safety parameters determined by the manufacturer, and,
for installations with a mixing valve, the device may exceed the
user set point temperature.
---------------------------------------------------------------------------
As a result, in this final rule, DOE has decided not to establish a
definition for ``demand-response water heater.'' DOE has considered the
various requirements which stakeholders suggested should be criteria
for a product to be called a ``demand-response water heater'' and has
determined that, while standardization of these requirements may be
beneficial to utilities and industry, it is unnecessary at this time
because DOE can instead describe the types of water heaters that can
temporarily increase the storage tank temperature only in response to
instructions from a utility or third-party demand response program
without defining ``demand-response water heater''. Additionally, as
discussed in section III.E.1.b of this document, this final rule only
amends the test procedure to provide a means for testing water heaters
in the highest tank temperature setting, and DOE is adopting it as a
voluntary measure in this test procedure for certain electric storage
water heaters. As such, it is no longer necessary to establish a
definition for ``demand-response water heater'' in this test procedure
rulemaking.
2. Heat Pump Water Heaters
As discussed in section III.A of this document, EPCA defines
``water heater'' to include, in relevant part, (A) storage type units
which heat and store water at a thermostatically controlled
temperature, including . . . electric storage water heaters with an
input of 12 kilowatts or less; (B) instantaneous type units which heat
water but contain no more than one gallon of water per 4,000 Btu per
hour of input, including . . . electric instantaneous water heaters
with an input of 12 kilowatts or less; and (C) heat pump type units,
with a maximum current rating of 24 amperes at a voltage no greater
than 250 volts, which are products designed to transfer thermal energy
from one temperature level to a higher temperature level for the
purpose of heating water, including all ancillary equipment such as
fans, storage tanks, pumps, or controls necessary for the device to
perform its function. (42 U.S.C. 6291(27))
Because the maximum current and voltage ratings for consumer heat
pump type units are 24 amperes at no more than 250 volts, the maximum
electrical input for this type of product is determined to be 6
kilowatts.\27\ In this final rule, DOE is providing clarifications on
how these definitions apply to electric and gas-fired heat pump storage
water heaters.
---------------------------------------------------------------------------
\27\ Power equals current times voltage, so the definition of
consumer heat pump type unit corresponds to a maximum power rating
of 6,000 W, or 6 kW (i.e., 24 A times 250 V equals 6,000 W).
---------------------------------------------------------------------------
a. Electric Heat Pump Storage Water Heaters
EPCA is not explicit as to whether heat pump type units are
considered a subcategory of storage type units and
[[Page 40416]]
instantaneous type units. ``Storage type units'' and ``instantaneous
type units'' are not exclusive of ``heat pump type units.'' Based on
the statute's ``water heater'' definition, an electric heat pump type
unit could be covered under the ``water heater'' definition's
description of storage type units (if it heats and stores water at a
thermostatically controlled temperature with an input of 12 kilowatts
or less) or instantaneous type unit (if it heats water and contains no
more than one gallon of water per 4,000 Btu per hour of input and has
an input of 12 kilowatts or less).
On November 10, 2016, DOE published a final rule in the Federal
Register (the November 2016 Final Rule) that treated heat pump-type
units as a subcategory of the other two types of units listed in the
definition of water heater. Specifically, DOE stated in the November
2016 final rule that a heat pump water heater with a total rated input
of less than 12 kilowatts would be a consumer water heater because EPCA
classifies electric water heaters with less than 12 kilowatts rated
electrical input as consumer water heaters. 81 FR 79261, 79301-79302.
In the January 2022 NOPR, DOE responded to comments requesting
clarification on whether electric heat pump water heaters between 6
kilowatts and 12 kilowatts of input should be classified as consumer
water heaters or commercial water heaters. 87 FR 1554, 1561-1563 (Jan.
11, 2022). Upon further review of EPCA and the water heater market, DOE
initially determined in the January 2022 NOPR that the interpretation
presented in the November 2016 Final Rule was not the best reading of
EPCA. Id.
In the January 2022 NOPR, DOE explained that the structure of the
statutory definition of ``water heater'' in the Energy Conservation
Program for Consumer Products in Part A of EPCA lists each type of
water heater at equal subparagraph designations. Therefore, when
defining ``water heater'' for the purpose of determining whether a
water heater is a consumer water heater, the energy use criteria
specified for heat pump-type units is to be applied separately and
distinctly from the criteria specified for the categorizations of
storage-type units and instantaneous-type units. Therefore, DOE had
tentatively determined that heat pump water heaters, which operate with
a maximum current rating greater than 24 amperes or at a voltage
greater than 250 volts, are more appropriately covered as commercial
water heaters than consumer water heaters. 87 FR 1554, 1561-1562 (Jan.
11, 2022).
As explained in the January 2022 NOPR, there are three other
reasons why DOE tentatively concluded that the revised interpretation
would be more applicable to the residential water heater market.
First, heat pump technology is capable of providing heat output
which exceeds the energy input. A heat pump type unit with an input
rate of 12 kilowatts could have a heating capacity (i.e., output
capacity) of approximately 42 kilowatts, which is 3.6 times the output
heating capacity provided by the largest possible consumer electric
storage type water heater (i.e., 11.8 kilowatts).\28\ While a heat
pump-type unit with a 12 kilowatt input capacity could theoretically be
designed and installed in a residential application, its water heating
capacity (i.e., output capacity) would far exceed the water heating
demand of any residential installation. 87 FR 1554, 1562 (Jan. 11,
2022).
---------------------------------------------------------------------------
\28\ A 12-kW electric resistance water heater with an assumed
recovery efficiency of 98 percent would have an output heating
capacity of 11.8 kW (12 kW x 0.98 = 11.8 kW). An electric heat pump-
type water heater with a 12-kW input capacity, with an assumed
recovery efficiency of 350 percent, would have an output heating
capacity of 42 kW (12 kW x 3.5 = 42 kW), which is 3.6 times greater
than the 11.8 kW output heating capacity of an electric resistance
water heater with equivalent input capacity.
---------------------------------------------------------------------------
Second, the DOE test procedure for consumer water heaters at the
time of the November 2016 Final Rule only covered heat pump water
heaters which have ``a maximum current rating of 24 amperes (including
the compressor and all auxiliary equipment such as fans, pumps,
controls, and, if on the same circuit, any resistive elements) for an
input voltage of 250 volts or less,'' and, therefore, electric heat
pump water heaters with greater than 24 amperes at 250 volts were not
considered at the time when the current energy conservation standards
for consumer water heaters were established (April 2010). As a result,
these current standards do not reflect energy usage for heat pump water
heaters between 6 kilowatts and 12 kilowatts, and such products are
more appropriately rated to the commercial water heater test procedure
(10 CFR 431.106) and evaluated against the maximum standby loss
standards for this equipment (10 CFR 431.110(a)). 87 FR 1554, 1562
(Jan. 11, 2022).
Third, based on its review of the market, DOE is aware of
integrated heat pump water heaters, split-system heat pump water
heaters, and heat pump-only water heaters (i.e., circulating heat pump
water heaters) which are designed for use in residential applications,
and all such products are rated at or below 24 A/250 V of input.
Integrated heat pump water heaters, which consist of an air-source heat
pump in one assembly with a storage tank, typically operate with 240-
volt input. Although integrated heat pump water heaters usually have
backup 4.5-kilowatt electric resistance heating elements, the elements
do not operate simultaneously, which ensures that these products do not
surpass 6 kilowatts of input or 24 A/250 V at any given time. Some
integrated heat pump water heaters are designed to operate at only 120
volts of input (i.e., ``retrofit-ready,'' ``plug-in,'' or ``120-volt''
heat pump water heaters). Split-system heat pump water heaters, which
consist of a separate heat pump and storage tank that are sold together
(where the heat pump components are usually situated outdoors), are
also covered by the currently applicable appendix E test procedure and
have electrical input ratings which do not exceed 24 A/250 V.
Circulating heat pump water heaters (or ``heat pump-only'' water
heaters), which consist of only a heat pump module and must be
installed with a separate storage tank, similarly do not exceed this
limit, and there are models of circulating heat pump water heaters
which are intended to operate on 120 volts of input. Alternative source
heat pump water heaters (e.g., ground-source or water-source), were not
considered in this rulemaking due to their predominant use as
commercial products. 87 FR 1554, 1563 (Jan. 11, 2022).
In this final rule, DOE maintains the revised interpretation as
discussed in the January 2022 NOPR. To clarify this interpretation in
the regulatory definitions, DOE is amending the definition of
``commercial heat pump water heater'' at 10 CFR 431.102 to reflect this
revised interpretation. The revised definition reads: ``Commercial heat
pump water heater (CHPWH) means a water heater (including all ancillary
equipment such as fans, blowers, pumps, storage tanks, piping, and
controls, as applicable) that uses a refrigeration cycle, such as vapor
compression, to transfer heat from a low-temperature source to a
higher-temperature sink for the purpose of heating potable water, and
operates with a current rating greater than 24 amperes or a voltage
greater than 250 volts. Such equipment includes, but is not limited to,
air-source heat pump water heaters, water-source heat pump water
heaters, and direct geo-exchange heat pump water heaters.''
In the April 2020 RFI, DOE requested feedback on the need for
creating a separate definition for ``electric heat pump storage water
heater,'' similar to the definition in the March 2019
[[Page 40417]]
ASHRAE Draft 118.2, or whether the current DOE definitions in 10 CFR
430.2 for ``electric storage water heater'' and ``water heater,'' which
include ``heat pump type units,'' would adequately cover such products
for the purpose of performing the DOE test procedure. 85 FR 21104,
21110 (April 16, 2020). The Department's tentative determination in the
January 2022 NOPR was that a separate definition would not be needed
because the current definitions were sufficient to describe these
products. 87 FR 1554, 1563-1564 (Jan. 11, 2022). In response to the
January 2022 NOPR, Rheem requested that the product class-specific
definitions include or refer to the ``heat pump type'' requirements in
EPCA. (Rheem, No. 31 at p. 2) BWC agreed with DOE's assessment that
consumer heat pump water heaters operate at no greater than 24 amperes
at 250 volts. (BWC, No. 33 at pp. 1-2)
Additionally, DOE received several comments on the January 2022
NOPR regarding definitions for specific types of heat pump water
heaters used in residential applications.
The CA IOUs recommended that DOE should supplement its test
procedure definitions to address heat pump water heaters rated to
operate at 120 volts of input. More specifically, the CA IOUs
recommended that DOE develop a separate definition for 120-volt heat
pump water heaters in the test procedure and consider any
distinguishing characteristics that might require changes to the test
procedure to represent their real-world performance accurately. These
commenters argued that a separate definition would allow for the
possibility of separate energy conservation standards for these
products. The CA IOUs stated that they expect the first 120-volt heat
pump water heaters to appear on the retail market in 2022 and noted
that the California Energy Commission recently adopted a goal to
install six million heat pumps (for space and water heating) by 2030,
many of which they anticipate will be 120-volt heat pump water heaters.
(CA IOUs, No. 36 at p. 4)
AET expressed support for the inclusion of heat pump-only water
heaters within the scope of the DOE test procedure but suggested
revising the terminology so as to differentiate a ``heat pump water
heater without a tank'' from a ``heat pump water heater with a tank.''
(AET, No. 29 at p. 2) On this point, DOE notes that there is not yet a
particular term for these products defined at 10 CFR 430.2 or in
appendix E. These products may be referred to using any of the terms
mentioned by AET, but the clearest description of these products is
``circulating heat pump water heaters.'' Circulating water heaters are
discussed further in section III.A.4.a of this document. DOE is
adopting a definition for ``circulating water heater'' in this final
rule, which will include these products.
Rheem recommended that DOE include split-system heat pump water
heaters in the ``water heaters requiring a storage tank'' definition
proposed in the January 2022 NOPR and that DOE define ``integrated heat
pump water heater'' to distinguish them from split-system water
heaters. (Rheem, No. 47 at p. 4) AHRI stated that a definition of
``split-system water heater'' is not required if DOE does not include
the proposed optional additional test conditions in this rulemaking.
(AHRI, No. 55 at p. 5)
In response to Rheem's comments, a split-system water heater is not
necessarily a ``water heater requiring a storage tank,'' as proposed in
the January 2022 NOPR, because for a water heater to meet the proposed
definition of ``water heater requiring a storage tank'' would mean
there is no storage tank specified or supplied by the manufacturer but
that it requires one for testing and operation. A split-system water
heater, however, may have a manufacturer supplied or specified tank
and, as such, would not necessarily fall under the definition of a
``water heater requiring a storage tank.'' When the tank is specified
or supplied by the manufacturer, that tank should be used for testing,
rather than a water heater or storage tank that meets the default
conditions that were proposed to be added in section 4.10 of appendix
E. Additionally, in response to the suggestion that DOE define
``integrated heat pump water heater,'' DOE notes that, as discussed
later in this section, it is modifying the definition of a ``split-
system water heater'' based on comments to mean a heat pump-type water
heater in which at least the compressor, which may be installed
outdoors, is separate from the storage tank. Therefore, heat pump water
heaters that do not fall under the definition of ``split-system water
heater'' adopted in this final rule would be integrated heat pump water
heaters, as the refrigeration components would be integrated with the
tank. Thus, it is unnecessary to separately define ``integrated heat
pump water heaters,'' and the term would not be used in the test
method. Creating additional definitions for this configuration may lead
to confusion. In response to AHRI's comment, as discussed and for the
reasons explained in section III.C.7 of this document, DOE has decided
to include the proposed optional additional test conditions in this
rulemaking, and, thus, the Department has defined the term ``split-
system water heater.''
A.O. Smith requested that DOE clearly define ``heat pump-only water
heater'' and elucidate how appendix E applies to them. (A.O. Smith, No.
51 at p. 5) BWC requested that DOE clarify in its definitions the
difference between split-system and heat pump-only water heaters. (BWC,
No. 48 at p. 1)
In response, a heat pump-only water heater is considered a
circulating water heater, which is a type of heat pump water heater,
falls under the circulating water heater product classes, and is
covered under the associated provisions of appendix E. Such
distinctions were previously discussed in the January 2022 NOPR. 87 FR
1554, 1565 (Jan. 11, 2022). These units have an input greater than or
equal to 4,000 Btu per hour per gallon, and accordingly, they are
considered instantaneous water heaters. In contrast, split-system heat
pump water heaters (which, unlike heat pump-only units, are distributed
with a storage tank) are considered storage water heaters.
After considering these comments, DOE has decided to affirm
coverage in this test procedure final rule for all of the
aforementioned types of consumer heat pump water heaters. In
particular, DOE has determined that the current definitions of ``heat
pump-type'' and ``electric storage water heater'' adequately cover the
electric heat pump water heaters on the market that are representative
of residential use (including, but not limited to, integrated 240-volt
and 120-volt heat pump water heaters, split-system heat pump water
heaters, and circulating heat pump water heaters), and that a separate
definition for ``electric heat pump water heaters'' is not needed in
order to appropriately characterize the test procedure for consumer
water heaters and residential-duty commercial water heaters.
At the time of this final rule, DOE is only aware of a small number
of 120-volt integrated heat pump water heaters and circulating heat
pump water heaters on the market. Therefore, DOE has limited
information to determine whether there are any distinguishing
characteristics of these products which would necessitate tailored test
procedure requirements in order to produce ratings that are
representative, reproducible, and repeatable. One manufacturer has
publicly certified
[[Page 40418]]
ratings \29\ for 120-volt electric storage heat pump models using the
currently applicable appendix E test procedure (without the use of a
test procedure waiver), so DOE, therefore, concludes that the appendix
E test procedure is appropriate and representative for these models.
DOE is aware, however, that default mode operation of 120-volt electric
storage heat pump water heaters may require raising the tank
temperature above the delivery setpoint in order to meet consumer
expectations of first hour rating (FHR), and further discussion of
potential impacts of storage tank overheating on ratings for 120-volt
electric storage heat pump water heaters as a result of this final
rule's action can be found in section III.E.1 and III.J.3 of this
document.
---------------------------------------------------------------------------
\29\ DOE reviewed public certification data in its Compliance
Certification Management System (CCMS) database, found online at
www.regulations.doe.gov/certification-data/#q=Product_Group_s%3A*.
---------------------------------------------------------------------------
In response to the July 2022 SNOPR, which proposed optional ambient
test conditions and new definitions for ``split-system water heaters,''
AHRI and A.O. Smith requested that DOE change its definition of
``split-system water heater'' to the definition used by ENERGY STAR,
which specifies that the compressor, evaporator, and/or condenser are
separated from a storage tank that is specified by the manufacturer and
rated as a single system. (AHRI, No. 55 at p. 5; A.O. Smith, No. 51 at
p. 4) A.O. Smith offered an alternative definition to DOE's earlier
definition of ``split-system heat pump water heater'' which specified
the heat pump as being an outdoor component. (A.O. Smith, No. 51 at pp.
4-5)
A.O. Smith, NEEA, and the CA IOUs stated that it is unnecessary for
the definition of ``split-system water heater'' to specify the location
of specific components and requested that DOE eliminate the distinction
between indoor and outdoor components. (A.O. Smith, No. 51 at p. 5; CA
IOUs, No. 52 at pp. 4-5; NEEA, No. 56 at p. 2) The CA IOUs stated that
the compressor should be specified as the component separate from the
storage tank, rather than the heat pump, to more generally reflect
split-system water heaters. (CA IOUs, No. 52 at pp. 4-5)
NEEA additionally recommended that DOE should not include
references to ``indoor'' or ``outdoor'' in its proposed definition of
``split-system heat pump water heater,'' as outdoor installation of the
heat pump component does not necessarily follow the splitting of
heating and storage functions into separate components, and an all-
indoor split-system HPWH has the potential to provide significant
benefits to consumers. NEEA added that adopting a split-system
definition that excludes such products could hinder manufacturers in
bringing them to market. (NEEA, No. 56 at p. 2) Similarly, Nyle
commented that the proposed definition is problematic because not all
split-system heat pump water heaters contain an outdoor component,
noting that it manufactures a 120-volt heat pump water heater for
indoor use only. Nyle suggested revising the definition to indicate
that a split-system heat pump water heater means a heat pump-type water
heater where the storage unit and heat pump components are independent
from one another but must be connected to operate (i.e., through
refrigerant lines, water piping, or via a thermal storage device).
(Nyle, No. 57 at p. 1)
In order to address the need for separate test conditions for
split-system water heaters (see section III.C.7 of this document for a
discussion on optional test conditions, which simulate different indoor
and outdoor air conditions for the different components of a split-
system water heater), DOE is adopting a definition for this subset of
heat pump water heaters at 10 CFR part 430, subpart B, appendix E,
section 1.14.
In response to these comments, DOE acknowledges that it is not
necessary to specify the location of the components and/or the storage
tank in the definition of ``split-system heat pump water heater'' as
long as they are separate. Therefore, DOE has changed the definition of
``split-system heat pump water heater'' to mean a heat pump-type water
heater in which at least the compressor, which may be installed
outdoors, is separate from the storage tank. This definition still
reflects that which is used in NEEA's Advanced Water Heating
Specification (AWHS) version 8.0 (AWHS v8.0),\30\ with minor
modifications.
---------------------------------------------------------------------------
\30\ AWHS v8.0 was published by NEEA on March 1, 2022. Although
early editions of the AWHS focused primarily on providing more
representative performance metrics for heat pump water heaters in
cold climates, the latest editions are now more broadly focused on
providing representative performance metrics for heat pump water
heaters across all climates. AWHS v8.0 includes separate test
condition requirements for integrated and split-system heat pump
water heaters. These test conditions are discussed further in detail
in section III.C.1 of this final rule. (Available at: neea.org/resources/advanced-water-heating-specification-v8.0) (Last accessed
on Sept. 19, 2022).
---------------------------------------------------------------------------
Additionally, a new definition for ``circulating water heater'' is
being established in this final rule at 10 CFR 430.2, as discussed in
section III.A.4.a of this document. This product category includes heat
pump-only water heaters, which is also discussed in section III.A.4.a
of this document. Specific testing provisions for circulating water
heaters are being newly established in this final rule, as discussed in
section III.D.4 of this document.
b. Gas-Fired Heat Pump Storage Water Heaters
The statutory definition for a ``heat pump type'' water heater (see
42 U.S.C. 6291(27)(C)) is not specific to electric heat pump type water
heaters. Gas-fired heat pump storage water heaters typically use an
absorption or adsorption refrigeration cycle, driven by a gas burner,
to transfer heat from the surrounding air to the water inside the water
heater.
In the July 2014 Final Rule, DOE codified a definition for ``gas-
fired heat pump water heater'' as follows:
Gas-fired heat pump water heater means a water heater that uses gas
as the main energy source, has a nameplate input rating of 75,000 Btu/h
(79 MJ/h) or less, has a maximum current rating of 24 amperes
(including all auxiliary equipment such as fans, pumps, controls, and,
if on the same circuit, any resistive elements) at an input voltage of
no greater than 250 volts, has a rated storage volume not more than 120
gallons (450 liters), and is designed to transfer thermal energy from
one temperature level to a higher temperature level to deliver water at
a thermostatically controlled temperature less than or equal to 180
[deg]F (82 [deg]C). 79 FR 40542, 40567 (July 11, 2014).
Then, in the November 2016 Final Rule, DOE reasoned that even
though gas-fired heat pump water heaters were covered by the existing
test procedure, this definition was extraneous because it is not
specifically referenced in any part of DOE's test procedures or energy
conservation standards for consumer water heaters. 81 FR 79261, 79261,
79287 (Nov. 10, 2016). The definition for ``gas-fired heat pump water
heater'' was deleted, and the current definition for ``gas-fired
storage water heater'' was added instead. Id. at 81 FR 79320-79321.
Since the deletion of the definition in the November 2016 Final
Rule, ASHRAE published an updated version of the test standard 118.2,
``Method of Testing for Rating Residential Water Heaters and
Residential-Duty Commercial Water Heaters,'' in January 2022 (ASHRAE
118.2-2022) (see section III.B.2 for further discussion of this
standard). The January 2022 NOPR issued prior to publication of ASHRAE
118.2-2022 and assessed public review drafts of ASHRAE 118.2-2022--all
of which still included a definition for
[[Page 40419]]
``gas-fired heat pump storage water heater.'' The definition for ``gas-
fired heat pump storage water heaters'' in the public review drafts of
ASHRAE 118.2-2022 was adopted in section 2.4 of the final published
version, which defines the term as follows:
(a) Use gas as the main energy source,
(b) Have a nameplate input rating of 20,000 Btu/h (26.4 MJ/h) or
less,
(c) Have a maximum current rating of 24 amp (including all
auxiliary equipment, such as fans, pumps, controls, and, if on the same
circuit, any resistive elements) at an input voltage of no greater than
250 V,
(d) Have a rated storage volume not more than 120 gal (450 L), and
(e) Are designed to transfer thermal energy from one temperature
level to a higher temperature level to deliver water at a
thermostatically controlled temperature less than or equal to 180
[deg]F (82 [deg]C).
In the January 2022 NOPR, DOE stated that, currently, a water
heater that uses gas as the main energy source, has a nameplate input
rating of 75,000 Btu/h or less, and contains more than one gallon of
water per 4,000 Btu per hour of input is a gas-fired storage water
heater. (10 CFR 430.2) If the gas-fired storage water heater also has a
heat pump with a maximum current rating of 24 amperes at a voltage no
greater than 250 volts, is designed to transfer thermal energy from one
temperature level to a higher temperature level for the purpose of
heating water, including all ancillary equipment such as fans, storage
tanks, pumps, or controls necessary for the device to perform its
function, it would be a heat pump type unit (see 10 CFR 430.2). 87 FR
1554, 1564 (Jan. 11, 2022).
DOE also noted in the January 2022 NOPR that this industry
definition establishes the scope of coverage for these products more
narrowly than the current definitions for ``gas-fired storage water
heater'' and ``heat pump type'' water heater together. Specifically,
the ASHRAE 118.2-2022 definition limits the input rate at 20,000 Btu/
h--presumably because the input rates of models currently in
development for residential applications are less than 20,000 Btu/h--
whereas the current definitions at 10 CFR 430.2 accommodate potential
future products up to 75,000 Btu/h. In recognition of the developing
market for gas-fired heat pump water heaters, DOE had tentatively
determined not to limit scope of coverage to only 20,000 Btu/h. 87 FR
1554, 1564 (Jan. 11, 2022).
In response to the January 2022 NOPR, BWC suggested DOE re-evaluate
whether current consumer water heater definitions adequately cover gas-
fired heat pump water heaters (as defined by ASHRAE) in light of
questions as to whether features related to these products depart from
the current consumer water heater definitions. (BWC, No. 33 at p. 2)
However, the commenter did not provide further details.
DOE did not receive any additional comments elucidating which
features may be of concern, and as a result, DOE is not able to
identify reasons to justify redefining gas-fired heat pump storage
water heaters in a way that departs from the current definitions. At
the time of this final rule, such products are still mostly in the
field trial stage in the United States, and, thus, they are not mass-
produced, nor are they widely distributed in the commercial market.
However, DOE is aware that products currently under development consist
of a modulating gas-fired burner that powers an absorption cycle using
a design which would meet the definition for a ``split-system heat pump
water heater'' (discussed in section III.A.2.a of this document).
Nonetheless, because the current definitions for ``gas-fired storage
water heater'' and ``heat pump type'' water heater are sufficiently
broad, such products would remain appropriately encompassed within the
current scope of coverage. Should more designs of gas-fired heat pump
water heaters (either storage type or instantaneous type) emerge into
the water heaters market, DOE would evaluate the definitions and
appropriateness of its test methods for gas-fired and heat pump
products as they would apply to this novel technology.
Moreover, while ASHRAE 118.2-2022 does define gas-fired heat pump
storage water heaters, there are no unique test methods for these
products outlined in the industry test standards. Similar to the
determination in the November 2016 Final Rule, DOE has concluded that
the definition in ASHRAE 118.2-2022 is extraneous. Furthermore, given
that no concrete concerns regarding the applicability of the current
methods to gas-fired heat pump water heaters have been identified, DOE
has determined not to adopt any specific provisions for these in its
amended appendix E test procedure at this time.
3. Residential-Duty Commercial Water Heaters
In this rulemaking, DOE has sought comment on the definition for
``residential-duty commercial water heater,'' which defines a category
of commercial water heaters that are subject to the appendix E test
procedure due to their residential applications. 85 FR 21104, 21108
(April 16, 2020).
In the January 2022 NOPR, DOE acknowledged that some water heaters
intended for commercial use are covered by the residential-duty
commercial water heater definition and tested and rated to the appendix
E test procedure and residential-duty commercial water heater energy
conservation standards in terms of UEF. DOE explained that these water
heaters have characteristics that are similar to water heaters with
residential applications and, as such, under 42 U.S.C. 6295(e)(5)(F),
cannot be excluded from being tested and rated using the consumer water
heaters test procedure and residential-duty commercial water heater
energy conservation standards. Thus, DOE did not propose amendments to
this definition. 87 FR 1554, 1566 (Jan. 11, 2022).
DOE has determined that whether a product is marketed as commercial
or residential may not always be indicative of the intended
installation location. The January 2022 NOPR provided the example of
water heaters that are intended for residential use but sometimes
marketed as ``commercial-grade'' as a means to convey an expectation of
reliability. 87 FR 1554, 1566-1567 (Jan. 11, 2022).
In commenting on the January 2022 NOPR, with regards to
residential-duty commercial water heaters, AET commented that the
method used to evaluate consumer electric instantaneous and
residential-duty commercial electric instantaneous water heaters in the
December 2016 Conversion Factor Final Rule was not approved for these
products, and the energy conservation standards DOE issued for consumer
water heaters could not be met by them. AET argued that the energy
conservation standards for residential-duty commercial electric
instantaneous water heaters were based on performance for fossil fuel-
fired commercial tankless water heaters as opposed to actual product
testing, and, therefore, the commenter asserted that the minimum
efficiency requirements for residential-duty commercial electric
instantaneous water heaters are too low and should be updated. (AET,
No. 29 at pp. 14-15)
DOE understands that the commenter's discussion of the ``method
used to evaluate consumer electric instantaneous and residential-duty
commercial electric instantaneous water heaters'' refers to the
analytical approach in 2016 that was used to predict the UEF values of
these water heaters from existing representations of maximum GPM (see
81 FR 96204,
[[Page 40420]]
92616-92617 (Dec. 29, 2016)) and thermal efficiency (see 81 FR 96204,
96218 (Dec. 29, 2016)). At this time, however, the current appendix E
test procedure does provide a method to test and rate these water
heaters.\31\ DOE notes that there are currently consumer and
residential-duty commercial electric instantaneous water heaters
certified to meet the applicable energy conservation standards.
---------------------------------------------------------------------------
\31\ Section 5.3.2 of appendix E details the Max GPM rating test
for flow-activated water heaters, Table II in section 5.4.1 of
appendix E details how to select draw pattern based on Max GPM
rating, and sections 5.4.2 and 5.4.3 of appendix E detail the test
sequence.
---------------------------------------------------------------------------
Otherwise, DOE did not receive any comments specifically pertaining
to the definition for residential-duty commercial water heaters.
Therefore, DOE is not amending the definition for ``residential-duty
commercial water heater'' in this final rule for the reasons previously
discussed. DOE may consider potential amended standards for
residential-duty commercial electric instantaneous water heaters in a
separate rulemaking addressing the energy conservation standards for
commercial water heaters.\32\
---------------------------------------------------------------------------
\32\ DOE is concurrently evaluating energy conservation
standards for commercial water heaters in Docket No. EERE-2021-BT-
STD-0027.
---------------------------------------------------------------------------
4. Specialty Water Heaters
As first proposed in the January 2022 NOPR, this final rule expands
the scope of coverage of the appendix E test procedure to include low-
temperature water heaters and circulating water heaters, which both
fall under the statutory definition of consumer ``water heater'' but
did not previously have test methods appropriate for their unique
operation. DOE is also re-instating an inadvertently omitted definition
for ``tabletop water heater'' at 10 CFR 430.2. In addition, DOE has
considered whether to address solar water heaters in the consumer water
heaters test procedure, but the Department has determined not to expand
the scope of coverage of the appendix E to these products at this time.
DOE may further consider solar water heaters in a separate rulemaking
in the future. Each of these categories of water heaters is discussed
in the following subsections.
Dyson generally commented that indirect circulation systems
especially have an extraordinarily flexible use case and can be
implemented in both warm and cool regions. (Dyson, No. 28 at p. 1) DOE
understands this comment to refer to systems which use a separate
boiler to provide the heat source for domestic water heating. However,
consumer boilers are not within the scope of this rulemaking.
a. Circulating Water Heaters
As discussed in section III.A of this document, a gas-fired
instantaneous water heater is a water heater that uses gas as the main
energy source, has a nameplate input rating less than 200,000 Btu per
hour, and contains no more than one gallon of water per 4,000 Btu per
hour of input. 10 CFR 430.2.
In the April 2020 RFI, DOE requested feedback on the typical
application of a specific configuration of gas-fired instantaneous
water heaters, commonly referred to as ``circulating gas-fired
instantaneous water heaters.'' 85 FR 21104, 21113 (April 16, 2020). As
explained in the April 2020 RFI, DOE has found that several
manufacturers produce consumer gas-fired instantaneous water heaters
that are designed to be used with a volume of stored water (usually in
a tank, but sometimes in a recirculating hot water system of sufficient
volume, such as a hydronic space heating or designated hot water
system) in which the water heater does not provide hot water directly
to fixtures, such as a faucet or shower head, but rather replenishes
heat lost from the tank or system through hot water draws or standby
losses by circulating water to and from the tank or other system. These
circulating gas-fired instantaneous water heaters are typically
activated by an aquastat \33\ installed in a storage tank that is sold
separately or by an inlet water temperature sensor. DOE further stated
that while the products identified by DOE are within the statutory and
regulatory definition of a consumer ``water heater'' and, therefore, a
covered product, the design and application of circulating gas-fired
instantaneous water heaters make testing to the currently applicable
Federal test procedure for consumer water heaters difficult, if not
impossible, as these products are not capable of delivering water at
the temperatures and flow rates specified in the UEF test method
contained therein. Id. As a result, the currently applicable appendix E
test procedure does not sufficiently cover circulating water heaters.
---------------------------------------------------------------------------
\33\ An ``aquastat'' is a temperature measuring device typically
used to control the water temperature in a separate hot water
storage tank.
---------------------------------------------------------------------------
DOE received several comments on the April 2020 RFI recommending
generally that DOE amend the regulatory definitions of gas-fired
instantaneous water heaters to exclude models designed exclusively for
commercial use even though they have input rates below the consumer
water heater input rate limit (i.e., <=200,000 Btu/h). AHRI and
individual manufacturers commented that these products are used in
commercial applications even though they may in certain cases meet the
statutory definition for a consumer water heater, and that the
residential draw pattern profiles may not be applicable. These comments
are discussed in detail in the January 2022 NOPR. 87 FR 1554, 1565
(Jan. 11, 2022).
In the January 2022 NOPR, DOE noted that 42 U.S.C. 6291(1) states
that a ``consumer product'' means any article of a type which, to any
significant extent, is distributed in commerce for personal use or
consumption by individuals. DOE also stated that its examination of
product literature has found that circulating water heaters are
predominately marketed for commercial applications. However, the input
rates of many of the available models are below the maximum input rate
of a consumer water heater and can, therefore, be suitable for
residential applications. DOE noted that there exist circulating heat
pump water heaters (heat pump-only water heaters) which operate in the
same manner as gas-fired circulating water heaters but are clearly
marketed for residential applications. Consequently, it is foreseeable
that there could be the potential for product substitution into the
consumer market. For these reasons, DOE tentatively determined that
circulating water heaters are covered ``consumer products.'' 87 FR
1554, 1565 (Jan. 11, 2022).
In the January 2022 NOPR, DOE proposed to include the following
definition at 10 CFR 430.2: ``Circulating water heater means an
instantaneous or heat pump-type water heater that does not have an
operational scheme in which the burner, heating element, or compressor
initiates and/or terminates heating based on sensing flow; has a water
temperature sensor located at the inlet of the water heater or in a
separate storage tank that is the primary means of initiating and
terminating heating; and must be used in combination with a
recirculating pump and either a separate storage tank or water
circulation loop in order to achieve the water flow and temperature
conditions recommended in the manufacturer's installation and operation
instructions.'' 87 FR 1554, 1565 (Jan. 11, 2022).
Commenters had varying viewpoints on this topic. AET expressed
general agreement with DOE's proposal to add a new definition and
product category for circulating water heaters. (AET, No. 29 at p. 1)
[[Page 40421]]
Rheem supported the addition of a definition for ``circulating
water heater'' to 10 CFR 430.2 and accompanying test procedures within
appendix E for such products that have residential applications, but
the commenter emphasized that the division between consumer and
commercial water heaters should be appropriately set. Rheem argued that
because a ``circulating water heater'' must use a separate storage
tank, circulating water heater product classes should be defined using
the storage-type unit input rate criteria (e.g., a gas-fired
circulating water heater with an input rate at or below 75,000 Btu/h is
a consumer water heater and greater than 75,000 Btu/h is a commercial
water heater). Rheem also recommended further investigation as to
whether certain capacities of storage-type water heaters could be
covered by the ``circulating water heater'' definition. Rheem added
that the ``circulating water heater'' definition should be amended to
allow a water temperature sensor at the outlet of the water heater.
(Rheem, No. 31 at p. 2)
BWC generally disagreed with DOE's proposal that circulating water
heaters should be covered as consumer products, arguing that these
products are exclusively installed in commercial applications as either
part of a recirculation loop or coupled to an unfired hot water storage
tank. BWC also noted that circulating water heaters heat water to
higher temperatures than consumer instantaneous water heaters do. BWC
argued that classifying circulating water heaters as consumer products
would provide little to no benefit to consumers, place additional
burden on manufacturers, and cause market confusion as to how these
products are specified and designed for field applications. (BWC, No.
33 at pp. 1-2)
AHRI expressed concerns about including circulating water heaters
in a residential water heaters test procedure because they are mostly
used in commercial applications, even with input rates below 200,000
Btu/h. In lieu of a solution in the test procedure, AHRI requested that
DOE reinstate the enforcement policy on circulating water heaters.\34\
(AHRI, No. 40 at p. 5) A.O. Smith provided similar comments, suggesting
that DOE should reissue the September 5, 2019 enforcement policy for
gas-fired circulating water heaters, or alternatively identify them in
the test procedure as ``historically regulated as commercial water
heating equipment'' that ``can be tested via the thermal efficiency
energy metrics; and . . . therefore should not be subjected to UEF
requirements.'' (A.O. Smith, No. 37 at pp. 2-3) Like AHRI and A.O.
Smith, BWC recommended reinstating the September 2019 enforcement
policy to allow industry to determine the proper test procedure. (BWC,
No. 33 at pp. 1-2)
---------------------------------------------------------------------------
\34\ DOE had issued an enforcement policy for circulating water
heaters that expired on December 31, 2021.
---------------------------------------------------------------------------
EEI requested more information on the size of the existing stock
and current sales volumes of circulating water heaters. (EEI, Jan. 27,
2022 Public Meeting Transcript, No. 27 at pp. 46-47)
In response, the Department reiterates that EPCA directed DOE to
develop a test procedure that applies, to the maximum extent
practicable, to all water heating technologies in use and to future
water heating technologies. (42 U.S.C. 6295(e)(5)(H)) As a circulating
water heater could be designed to operate in a similar manner to other
consumer water heaters (i.e., ``heat pump-only'' water heaters) and at
conditions appropriate for residential applications, DOE is required to
address these products in appendix E with other classes of consumer
water heaters. Furthermore, the definition for ``consumer product''
states that it is an article ``of a type'' that is distributed for
personal use or consumption by individuals ``without regard to whether
such article of such type is in fact distributed in commerce for
personal use or consumption by an individual.'' (42 U.S.C. 6291(1))
In response to Rheem's comment, circulating water heaters have high
input rate to storage volume ratios, which classify these products as
instantaneous-type water heaters (see 10 CFR 430.2 and 42 U.S.C.
6291(27)(B)). As such, the statutory definition of a storage-type water
heater (found at 42 U.S.C. 6291(27)(A)) does not cover circulating
water heaters because circulating water heaters have no more than one
gallon of water per 4,000 Btu/h of input. As a result, the 75,000 Btu/h
upper limit on the input rate for gas-fired storage-type water heaters
would not apply and will not be included in the scope of the definition
of ``circulating water heater.''
In response to BWC's comments, DOE notes that hot water delivery
temperature is not related to the statutory definition of coverage.
Rather, EPCA defines whether a water heater is covered as a consumer
product primarily according to its input rating, without regard to its
maximum hot water delivery temperature. DOE also concludes that
classifying circulating water heaters (that meet the input rating
requirements) as consumer products would provide a benefit to consumers
by allowing them to compare circulating water heaters alongside other
consumer water heaters with a UEF rating. Under 42 U.S.C. 6293(b), EPCA
requires that DOE test procedure not place undue burden on
manufacturers. In this instance, although test burden would increase
for manufacturers of circulating water heaters, it would not be
considered an undue burden, because these water heaters are consumer
products (by definition) and, therefore, should be subject to consumer
water heater test procedures. Contrary to BWC's assertion, DOE
concludes that covering circulating water heaters as consumer products
would reduce or resolve market confusion surrounding these products;
since they can be used in residential applications, they should be
rated accordingly.
In response to A.O. Smith's comment requesting DOE to consider
circulating gas-fired water heaters as historically regulated as
commercial water heaters and sufficiently described by the commercial
water heater metrics, DOE is not expanding the scope to products which
are ``historically regulated as commercial water heating equipment''
because DOE is only considering circulating gas-fired water heaters
with input rates less than or equal to 200,000 Btu/h, which meet the
existing statutory definition for consumer water heaters (and, thus, do
not meet the definition for gas-fired instantaneous commercial water
heaters). Furthermore, DOE clarifies that the Department is not
considering these gas-fired circulating water heaters (ones which meet
the existing statutory definition for consumer water heaters) to be
residential-duty commercial water heaters.
In response to the July 2022 SNOPR, BWC and AHRI once again
reiterated their understanding that circulating water waters are used
almost exclusively in commercial applications. (BWC, No. 48 at p.4;
AHRI, No. 55 at p. 5) BWC requested that DOE exercise authority granted
under the American Manufacturing Technical Corrections Act (AEMTCA) (42
U.S.C. 6295(e)(5)(F)) to regulate circulating water heaters as
commercial products even though they meet residential definitions, or
clearly demonstrate residential use. (BWC, No. 48 at p. 4) AHRI
suggested that addressing circulating water heaters in a consumer
rulemaking would cause confusion because their efficiency metric is
different from conventional consumer water heaters. (AHRI, No. 55 at p.
5)
In response, EPCA allows DOE to provide an exclusion from the
uniform
[[Page 40422]]
efficiency descriptor for specific categories of otherwise covered
water heaters that do not have residential uses, that can be clearly
described, and that are effectively rated using the current thermal
efficiency and standby loss descriptors. (42 U.S.C. 6295(e)(5)(F)(i))
\35\ However, DOE reads this statutory provision as only permitting
exclusion of water heaters that were categories of covered commercial
water heaters under section 342(a)(5) of EPCA [42 U.S.C. 6313(a)(5)].
It does not grant DOE authority to exclude consumer water heaters from
the ambit of the uniform test procedure, nor to somehow convert
consumer water heaters to commercial water heaters and to subject them
to energy conservation standards applicable to commercial water
heaters. In the present case, it is clear that the circulating water
heaters in question are consumer water heaters, given that they have
input rates below 200,000 Btu/h, and they otherwise meet the
definitional criteria of the statute for an instantaneous-type water
heater (see 42 U.S.C. 6291(27)(B)). Moreover, circulating water heaters
have the demonstrated ability to perform tank loading or recirculating
loop operation, as would indicate that these products do have clearly
described residential uses. Consequently, in response to these
comments, DOE notes that because both heat pump-only and gas-fired
circulating water heaters meet the requirements to be classified as
consumer products under EPCA, the statute requires that such water
heaters must be tested according to DOE test procedure at appendix E.
---------------------------------------------------------------------------
\35\ DOE acted in accordance with EPCA provisions as specified
at 6295(e)(5)(F)(i) when establishing product classes for
residential-duty commercial water heaters. In a July 2014 Final Rule
establishing the UEF test procedure, DOE determined that covered
commercial water heating equipment that did not meet the definition
of a ``residential-duty commercial water heater'' met the criteria
in EPCA for exclusion from the uniform efficiency descriptor. 79 FR
40542, 40545-40547 (July 11, 2014).
---------------------------------------------------------------------------
This final rule establishes a test method to determine the UEF of
consumer circulating water heaters. Effective and compliance dates are
discussed further in section III.I of this document.
In development of this final rule, DOE was not able to discern
rates of shipments and amount of stock for consumer circulating water
heaters as EEI had requested. However, DOE did identify circulating
water heater models currently on the market that are consumer water
heaters. DOE has determined that circulating water heaters may have a
water temperature sensor at the inlet or at the outlet of the water
heater--as suggested by Rheem-- and, therefore, the Department agrees
with Rheem and is adopting the following definition for ``circulating
water heater'' at 10 CFR 430.2:
Circulating water heater means an instantaneous or heat pump-type
water heater that does not have an operational scheme in which the
burner, heating element, or compressor initiates and/or terminates
heating based on sensing flow; has a water temperature sensor located
at the inlet or at the outlet of the water heater or in a separate
storage tank that is the primary means of initiating and terminating
heating; and must be used in combination with a recirculating pump and
either a separate storage tank or water circulation loop in order to
achieve the water flow and temperature conditions recommended in the
manufacturer's installation and operation instructions.
b. Low-Temperature Water Heaters
DOE has identified certain flow-activated water heaters that are
designed to deliver water at temperatures below the set point
temperature of 125 [deg]F 5 [deg]F (51.7 [deg]C 2.8 [deg]C) that is required by section 2.5 of the currently
applicable appendix E (hereinafter referred to as ``low-temperature''
water heaters). These low-temperature water heaters (often referred to
as ``handwashing'' or ``point-of-use'' water heaters in marketing
literature) typically have low heating rates, which requires the
testing agency to reduce the flow rate in order to be able to achieve
the outlet temperature within the set point temperature range. However,
these units also have a minimum activation flow rate below which the
unit shuts off. To the extent that a unit would stop heating water when
the flow rate is too low, there may be no flow rate at which the unit
would operate and deliver water at the outlet temperature required
under section 2.5 of appendix E. Further, the definition of water
heater or electric instantaneous water heater does not include a
minimum water delivery temperature. To the extent that a low-
temperature water heater uses electricity as the energy source, has a
nameplate input rating of 12 kilowatts or less, and contains no more
than one gallon of water per 4,000 Btu per hour of input, it would be
an electric instantaneous water heater. 10 CFR 430.2. Therefore,
because such products are within the scope of consumer water heater
coverage under EPCA, the appendix E test procedure should address them;
however, the currently applicable appendix E does not address them.
DOE requested information in the April 2020 RFI on testing these
products at a lower set point temperature and other potential changes
which may be necessary to accommodate these types of models. 85 FR
21104, 21113 (April 16, 2020). Several commenters on the April 2020 RFI
recommended that the test procedure be modified to indicate a lower set
point temperature for testing, such as the maximum water temperature
delivery that the model is capable of delivering (see NOPR discussion
for complete details). 87 FR 1554, 1582 (Jan. 11, 2022).
In the January 2022 NOPR, DOE proposed to define a ``low-
temperature water heater'' as an electric instantaneous water heater
that is not a circulating water heater and cannot deliver water at a
temperature greater than or equal to the set point temperature
specified in section 2.5 of appendix E to subpart B of this part when
supplied with water at the supply water temperature specified in
section 2.3 of appendix E to subpart B of this part. DOE also
tentatively determined that lowering the set point temperature for low-
temperature water heaters to their maximum possible delivery
temperature would allow these water heaters to be tested appropriately
and in a representative manner. As such, DOE proposed to require low-
temperature water heaters to be tested to their maximum possible
delivery temperature. 87 FR 1554, 1583 (Jan. 11, 2022).
AET agreed with DOE's proposal to add a new definition and product
category for low-temperature water heaters. (AET, No. 29 at p. 2) EEI
requested more information on the size of the existing stock, as well
as the current sales volumes of low-temperature water heaters. (EEI,
Jan, 27, 2022 Public Meeting Transcript, No. 27 at pp. 46-47) As with
circulating water heaters, DOE does not currently have this information
available but will continue to gather this data to the extent possible.
Rheem commented that the proposed definition for ``low-temperature
water heater'' should include water heaters with less than 10 gallons
of storage and clarify how it is different from other electric water
heaters. Rheem suggested that the installation and operation (I&O)
manual could be referenced to determine delivery temperature limits,
but alternatively, manufacturers could certify supplemental testing
instructions to DOE (i.e., when testing an electric instantaneous water
heater set according to the I&O manual and cannot meet the required
delivery temperature, the unit should be tested according to the
[[Page 40423]]
maximum delivery temperature). (Rheem, No. 31 at p. 3)
In response to the comments from Rheem, DOE notes that the
inability to deliver water at the specified outlet water temperatures
in appendix E is independent of the storage volume of the water heater.
Hence, restricting this product type definition to only those water
heaters that have less than 10 gallons of storage volume may
unintentionally leave larger low-temperature water heaters without
adequate test provisions in appendix E. This inability to deliver water
at 125 [deg]F 5 [deg]F--specifically at the appendix E flow
rate--serves as the key distinguishing factor between low-temperature
water heaters and other electric instantaneous water heaters. While the
maximum delivery temperatures may be noted in an I&O manual, as Rheem
suggested, this must be verified under the test conditions (most
notably the supply water temperatures) specified in appendix E. Section
5.2.2 of the amended appendix E includes instructions for setting the
outlet discharge temperature. Should the flow rate need to be reduced
in order to meet the outlet temperature requirements, then the product
would meet the criterion for a low-temperature water heater.
In this final rule, DOE is adopting a slightly modified definition
for ``low-temperature water heater,'' taking into account the comments
provided by Rheem. Accordingly, DOE is defining ``low-temperature water
heater'' as an electric instantaneous water heater that is not a
circulating water heater and cannot deliver water at a temperature
greater than or equal to the set point temperature specified in section
2.5 of appendix E when supplied with water at the supply water
temperature specified in section 2.3 of appendix E at the flow rate
specified in section 5.2.2.1 of appendix E. (DOE is including language
which specifies that the delivery temperature is that which results
from the appendix E flow rate.)
c. Tabletop Water Heaters
As discussed in the January 2022 NOPR, the definition for
``tabletop water heater'' was removed from appendix E as part of the
July 2014 Final Rule but was inadvertently not added to 10 CFR 430.2
(79 FR 40542, 40567-40568 (July 14, 2014)). 87 FR 1554, 1566 (Jan. 11,
2022). Up until then, ``tabletop water heater'' was defined as a water
heater in a rectangular box enclosure designed to slide into a kitchen
countertop space with typical dimensions of 36 inches high, 25 inches
deep, and 24 inches wide. 66 FR 4474, 4497 (Jan. 17, 2001). In the
January 2022 NOPR, after considering comments on the April 2020 RFI,
DOE proposed to add the definition of tabletop water heater 10 CFR
430.2, as it read prior to being removed from appendix E. 87 FR 1554,
1556.
In response to the January 2022 NOPR, AET agreed with re-instating
the definition for tabletop water heater at 10 CFR 430.2. (AET, No. 29
at p. 2)
DOE did not receive any other comment relating to this proposal, so
the Department is re-instating the definition for ``tabletop water
heater'' at 10 CFR 430.2, as proposed.
d. Solar Water Heaters
In response to an RFI published on May 21, 2020 (May 2020 RFI),
regarding the energy conservation standards for consumer water heaters
(85 FR 30853), the Solar Rating & Certification Corporation (SRCC)
recommended that solar water heating technologies be considered for
inclusion in the energy conservation standards and test procedures for
consumer water heaters. SRCC stated that without the involvement of
DOE, the industry metrics struggle to gain acceptance with policymakers
and consumers. SRCC also stated that DOE rulemakings to include solar-
equipped water heaters in regulations would serve to establish a single
performance metric and signal the legitimacy of solar water heating
technologies. (Docket: EERE-2017-BT-STD-0019, SRCC, No. 11 at pp. 3-4)
Subsequently, on October 7, 2020, SRCC published a draft test
procedure titled, ``Solar Uniform Energy Factor Procedure for Solar
Water Heating Systems'' (SUEF test method).\36\ The draft SRCC test
procedure addresses methods to test different types of solar water
heaters.
---------------------------------------------------------------------------
\36\ SRCC's draft Solar Uniform Energy Factor Procedure for
Solar Water Heating Systems is available at: www.iccsafe.org/wp-content/uploads/is_stsc/Solar-UEF-Specification-for-Rating-Solar-Water-Heating-Systems-20201012.pdf (Last accessed on July 13, 2022).
---------------------------------------------------------------------------
In the January 2022 NOPR, DOE responded to SRCC's comment on the
May 2020 RFI, by noting that on April 8, 2015, DOE published an energy
conservation standards NOPR (the April 2015 NOPR) addressing
definitions for consumer water heaters (80 FR 18784). 87 FR 1554, 1585
(Jan. 11, 2022). DOE further noted that the April 2015 NOPR proposed
definitions for ``solar-assisted fossil fuel storage water heater'' and
``solar-assisted electric storage water heater'' and clarified that
water heaters meeting these definitions are not subject to the amended
energy conservation standards for consumer water heaters established by
the April 2010 final rule. Id. DOE stated its intention to address
solar water heaters in a separate rulemaking. Id. In response to the
January 2022 NOPR, SEA commented that DOE should account for solar
water heaters in its test procedure and energy conservation standards.
(SEA, No. 24 at p. 1)
In response, DOE notes that ``solar water heater,'' as defined in
section 5.1 of SRCC's SUEF test method, include a solar collector or
module that is directly exposed to solar radiation outdoors and is
often separated from a storage tank and/or back-up water heater located
indoors. Therefore, appendix E does not currently accommodate these
products, and an in-depth evaluation of the modifications to appendix E
necessary to accommodate the testing of these products is required.
Given the lack of available test data utilizing the SUEF test method,
DOE is not amending the scope of the appendix E test procedure in this
rulemaking to explicitly include solar water heaters at this time.
However, DOE will continue to consider these solar water heater
products further, and depending upon the conclusions reached, the
Department may address them in a separate future rulemaking, as
appropriate.
B. Updates to Industry Standards
Prior to the effective date of this final rule, the applicable DOE
test procedure in appendix E referenced the following industry
standards:
ASHRAE 41.1-1986 (Reaffirmed 2006), Standard Method for
Temperature Measurement (ASHRAE 41.1-1986 (RA 2006)); and
ASTM D2156-09, (ASTM D2156-09), Standard Test Method for
Smoke Density in Flue Gases from Burning Distillate Fuels.
ASHRAE 41.1-1986 (RA 2006) was superseded by ASHRAE 41.1-2013 on
January 30, 2013 (ASHRAE 41.1-2013). ASHRAE 41.1-2013 was superseded by
ASHRAE 41.1-2020 on June 30, 2020. Updates to ASHRAE 41.1 are discussed
in section III.B.1 of this document.
ASTM D2156-09 was reapproved without modification in 2018 (ASTM
D2156-09 (RA 2018)). In the January 2022 NOPR, DOE proposed to update
appendix E to reference the most recent version of ASTM D2156 (i.e.,
ASTM D2156-09 (RA 2018)). 87 FR 1554, 1567 (Jan. 11, 2022). DOE did not
receive any comments in response to its proposal. Therefore, DOE is
updating the reference of ASTM D2156-09 to the most recent industry
standard (i.e., ASTM D2156-09 (RA 2018)). DOE is also incorporating by
reference ASTM E97-1987 (W1991) because it is
[[Page 40424]]
necessary to perform procedures within ASTM D2156-09 and ASTM D2156-09
(RA 2018).\37\
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\37\ Certain methods provided as part of ASTM E97-1987 (W1991)
are directly referenced by ASTM D2156-09 and ASTM D2156-09 (RA
2018). Copies of ASTM E97-1987 (W1991) are readily available from
ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West
Conshohocken, PA 19428-2959 or online at: www.astm.org. (Last
accessed on Sept. 20, 2022.)
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As discussed previously in this document, ASHRAE maintains a water
heater test procedure, ANSI/ASHRAE Standard 118.2, ``Method of Testing
for Rating Residential Water Heaters.'' The test procedure specified in
ANSI/ASHRAE 118.2-2006 (RA 2015) is similar to the DOE test procedure
that was in effect prior to the July 2014 final rule, although neither
the previous DOE consumer water heater test procedure nor the version
in place prior to this final rule reference ANSI/ASHRAE Standard 118.2-
2006 (RA 2015). In March 2019, ASHRAE published the March 2019 ASHRAE
Draft 118.2, the second public review draft of Board of Standards
Review (BSR) ANSI/ASHRAE Standard 118.2-2006R, ``Method of Testing for
Rating Residential Water Heaters and Residential-Duty Commercial Water
Heaters,'' which DOE referenced in the April 2020 RFI. 85 FR 21104,
21109-21111 (April 16, 2020). In April 2021, ASHRAE published
substantive changes to a previous public review draft \38\ of BSR ANSI/
ASHRAE Standard 118.2-2006R, ``Method of Testing for Rating Residential
Water Heaters and Residential-Duty Commercial Water Heaters'' (April
2021 ASHRAE Draft 118.2). The January 2022 NOPR examined these public
review drafts and discussed the differences between them and the DOE
test procedure. 87 FR 1554, 1567 (Jan. 11, 2022).
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\38\ The April 2021 ASHRAE Draft 118.2 shows only the proposed
substantive changes to the March 2019 ASHRAE Draft 118.2. All
sections not included in the April 2021 ASHRAE Draft 118.2 are as
proposed in the March 2019 ASHRAE Draft 118.2 or have not been
changed in a way that their content affects the results of the test
procedure proposed in the March 2019 ASHRAE Draft 118.2.
---------------------------------------------------------------------------
On January 24, 2022, ASHRAE published a revised edition of the
118.2 standard, ``Method of Testing for Rating Residential Water
Heaters and Residential-Duty Commercial Water Heaters,'' ASHRAE 118.2-
2022. The published edition finalized revisions shown in the March 2019
and April 2021 public review drafts.
In comments responding to the January 2022 NOPR, Lutz encouraged
DOE to incorporate by reference the industry test standard ASHRAE
118.2-2022. Lutz also recommended DOE review the test procedures in use
in Europe and Japan. (Lutz, No. 35 at p. 1) BWC supported DOE's
proposal to incorporate by reference the latest industry test
standards. (BWC, No. 33 at p. 2)
As discussed previously in this document, DOE will adopt industry
test standards as DOE test procedures for covered products and
equipment, unless such methodology would be unduly burdensome to
conduct or would not produce test results that reflect the energy
efficiency, energy use, water use (as specified in EPCA) or estimated
operating costs of that equipment during a representative average use
cycle. (10 CFR part 430, subpart C, appendix A, section 8(c)) In this
final rule, DOE is harmonizing provisions in appendix E to align with
certain updates in ASHRAE 118.2-2022 rather than incorporate the entire
industry test standard. DOE has concluded that certain updates in
ASHRAE 118.2-2022 do not meet the EPCA criteria outlined in this
paragraph and has, thus, determined that those updates should not be
incorporated into the DOE test procedure at appendix E. DOE's
assessment of ASHRAE 118.2-2022 is laid out in detail in section
III.B.2 of this document.
Finally, as discussed in the July 2022 SNOPR, DOE has reviewed
NEEA's Advanced Water Heating Specifications in order to assess
optional rating conditions and methods for heat pump water heaters.
This test procedure was identified by stakeholders in response to the
January 2022 NOPR as becoming a widely used methodology to provide
alternate ratings for heat pump water heaters at different climate
conditions. 87 FR 42270, 42275-42276 (July 14, 2022). In the January
2022 NOPR, DOE discussed comments previously received on the April 2020
RFI suggesting that DOE explore the usage of NEEA's Advanced Water
Heating Specification--which was at version 7.0 at the time--for
voluntary climate-specific efficiency representations of heat pump
water heaters. 87 FR 1554, 1580 (Jan. 11, 2022). In response to those
comments, DOE stated that it did not have data to indicate what
conditions would be representative for regional representations, and,
thus, DOE tentatively determined not to allow optional representations
of additional efficiency ratings at test conditions other than those
found in the DOE test procedure (which are representative of the Nation
as a whole), such as those made in accordance with NEEA's Advanced
Water Heating Specification. Id. However, as discussed in the July 2022
SNOPR, DOE has re-evaluated the benefits to consumers provided by
optional representations. 87 FR 42270, 42275-42277 (July 14, 2022). In
this final rule, DOE is including optional test conditions for heat
pump water heaters aligning with version 8.0 (the latest version) of
NEEA's Advanced Water Heating Specification. This matter is discussed
in further detail in section III.C.7 of this document.
1. ASHRAE 41.1-2020
As stated previously, ASHRAE 41.1-1986 (RA 2006) was superseded by
ASHRAE 41.1-2013, and ASHRAE 41.1-2013 was superseded by ASHRAE 41.1-
2020. ASHRAE 41.1-2013 removed the aspirated wet-bulb psychrometer
descriptions and stated they would be included in the next revision to
ASHRAE 41.6, ``Standard Method for Humidity Measurement.'' ASHRAE 41.6
was updated on July 3, 2014, and included the aspirated wet-bulb
psychrometer descriptions that were removed in ASHRAE 41.1-2013. ASHRAE
41.1-2013 also added uncertainty analysis for temperature measurements,
information for thermistor-type devices, descriptions for thermopiles,
and reorganized the standard to be consistent with other ASHRAE
standards. ASHRAE 41.1-2020 added conditional steady-state test
criteria and further updated the standard to meet ASHRAE's mandatory
language requirements.
As discussed in the January 2022 NOPR, section 3.2.1 of appendix E
requires that temperature measurements be made in accordance with
ASHRAE 41.1-1986 (RA 2006), and section 3.2.2 of appendix E provides
accuracy and precision requirements for air dry-bulb, air wet-bulb,
inlet and outlet water, and storage tank temperatures. Sections 5.2.2.1
and 5.3.2 of appendix E effectively require steady-state operation in
which the flow-activated water heater is operating at the maximum input
rate, is supplied with water at a temperature of 58 [deg]F 2 [deg]F, and delivers water at a temperature of 125 [deg]F
5 [deg]F. 87 FR 1554, 1567 (Jan. 11, 2022).
In the development of this final rule, DOE reviewed ASHRAE 41.1-
1986 (RA 22006), ASHRAE 41.1-2013, and ASHRAE 41.1-2020 and found that
the sections most relevant to appendix E are the temperature
measurement sections (i.e., sections 5 through 11 of ASHRAE 41.1-1986
(RA 2006), section 7 of ASHRAE 41.1-2013, and section 7 of ASHRAE 41.1-
2020) \39\ and the steady-state test criteria added in ASHRAE 41.1-
2020. The information in the
[[Page 40425]]
temperature measurement sections of the examined three versions of
ASHRAE 41.1 does not vary significantly. The additional steady-state
test criteria of ASHRAE 41.1-2020 varies significantly from and is more
stringent than \40\ the criteria specified in sections 5.2.2.1 and
5.3.2 of appendix E; however, the appendix E criteria supersede those
in ASHRAE 41.1-2020.
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\39\ Sections 5 through 11 of ASHRAE 41.1-1986 (RA 2006) were
combined into section 7 of ASHRAE 41.1-2013.
\40\ Section 5.5.3 of ASHRAE 41.1-2020 would be used to
determine steady-state operation within sections 5.2.2.1 and 5.3.2
of appendix E. Using this criteria, a flow-activated water heater
delivering water between 120 [deg]F and 121 [deg]F, which is within
the current delivery temperature range of 125 [deg]F 5
[deg]F, would not be considered in steady-state due to the
difference in temperature between the average of the sample and the
set point temperature.
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In the January 2022 NOPR, DOE tentatively determined that updating
the reference of ASHRAE 41.1-1986 (RA 2006) to the most recent version
of the industry standard (i.e., ASHRAE 41.1-2020) would not have a
significant effect on the test results, as the content of the relevant
sections of the ASHRAE 41.1 standards have not changed significantly
and the new content published in ASHRAE 41.1-2020 is superseded by
appendix E. As such, DOE proposed to update the reference of ASHRAE
41.1-1986 (RA 2006) to ASHRAE 41.1-2020. ASHRAE 41.1-2020 references
ASHRAE 41.6-2014 and requires its use when measuring the wet-bulb
temperature. The wet-bulb temperature is required when testing heat
pump water heaters to appendix E, and, therefore, DOE also proposed to
incorporate by reference ASHRAE 41.6-2014. 87 FR 1554, 1567-1568 (Jan.
11, 2022).
DOE did not receive any comments in response to its proposals to
incorporate by reference ASHRAE 41.1.-2020 and ASHRAE 41.6-2014;
therefore, DOE is incorporating by reference both standards in this
final rule for the reasons previously stated.
2. ASHRAE 118.2-2022
ASHRAE 118.2-2022, published on January 24, 2022 and approved by
ANSI on March 1, 2022, supersedes ASHRAE 118.2-2006. The foreword to
ASHRAE 118.2-2022 states that it was derived from the DOE appendix E
test procedure but also has several substantive changes. Specifically,
it notes that a major change was to move the conditions of the test
(air temperature, humidity, inlet and outlet water temperatures) and
draw patterns to an Informative Appendix A, ``U.S. Values for Test
Variables,'' indicating that this test standard has been revised such
that it can easily be applied with other test conditions and draw
patterns. Additionally, the foreword states that other changes include
clarifying the timing of the standby period, clarifying the end of the
recovery period, specifying that the density of water used in
calculations be measured at the outlet, and adjusting the FHR flow rate
for smaller tanks and defining a draw time limit if the water heater
can keep up with the FHR flow rate. The following subsections of this
final rule discuss the substantial differences between the updated
ASHRAE 118.2-2022 test standard and DOE's existing appendix E test
procedure. Based on a review of its own test data and stakeholder
feedback, the Department is not adopting every update in ASHRAE 118.2-
2022 into the amended appendix E test procedure promulgated by this
final rule. DOE has provided discussion of the amendments being made to
harmonize with ASHRAE 118.2-2022 in section III.B.2.b of this document,
whereas other updates in ASHRAE 118.2-2022 not being adopted are
discussed in section III.B.2.c of this document.
AET generally supported DOE's proposal to adopt most aspects of
ASHRAE 118.2 but noted that the definition of ``UEF'' in ASHRAE 118.2
is different from the definition of that term used by DOE. AET noted
that a UEF rating per ASHRAE Standard 118.2 would not be comparable to
a UEF rating per DOE's test procedure due to differences in test
conditions. (AET, No. 29 at pp. 6-7) DOE agrees that there could be
differences between the UEF test result from ASHRAE 118.2-2022 and the
amended appendix E test procedure from this final rule. Where
differences between these test procedures exist, the requirements at 10
CFR 430.23 and appendix E control. As such, manufacturers must ensure
that any representations of ``UEF'' are made in accordance with the
applicable version of the DOE test procedure.
a. Scope
Section 2 of ASHRAE 118.2-2022 states that the industry test
standard applies to water heaters designed to be capable of providing
outlet water at a controlled temperature of at least the nominal outlet
water temperature under the conditions specified in the standard. As
discussed in section III.A.4.b of this final rule, the January 2022
NOPR proposed to expand the scope of the DOE test procedure to include
low-temperature water heaters. 87 FR 1554, 1582-1583 (Jan. 11, 2022).
As such, the scope of ASHRAE 118.2-2022 is narrower than the test
procedure proposed in DOE's January 2022 NOPR and July 2022 SNOPR
because it explicitly excludes low-temperature water heaters. In order
to include low-temperature water heaters within the scope of the
amended appendix E test procedure, DOE is including testing provisions
which are not in ASHRAE 118.2-2022 to allow for the testing of low-
temperature water heaters. These test methods are discussed in section
III.E.3 of this final rule.
Additionally, the scope of ASHRAE 118.2-2022 differs significantly
from the scope of products covered under the EPCA definition for
consumer ``water heater'' and DOE's definition for ``residential-duty
commercial water heater.'' For example, section 2 of ASHRAE 118.2-2022
limits the storage volume for storage-type water heaters to 120 gallons
or less and limits the maximum delivery temperature to 180 [deg]F (82
[deg]C), whereas EPCA does not place limits on storage volume or
maximum delivery temperature for consumer water heaters. (42 U.S.C.
6291(27); 42 U.S.C. 6311(12)(A)-(B))) The scope of electric
instantaneous water heaters covered by ASHRAE 118.2-2022 equates to the
limit for residential-duty commercial electric instantaneous water
heaters; however, section 2.2 of ASHRAE 118.2-2022 does not specify any
limits on storage volume, and as a result, it covers certain commercial
electric instantaneous water heaters--whereas the currently applicable
appendix E test procedure does not. Section 2.1 of ASHRAE 118.2-2022
has a definition for ``electric heat-pump storage water heater'' which
explicitly limits the nameplate input rating to 12 kilowatts or less,
which, as discussed in section III.A.2.a of this final rule, does not
correspond to the statutory limit for heat pump-type units and would
include commercial heat pump water heaters (which are outside of the
scope of the appendix E test procedure). Finally, section 2.4 of ASHRAE
118.2-2022 limits gas-fired heat pump storage water heaters to
nameplate input ratings no greater than 20,000 Btu/h, which is
significantly lower than the statutory limit of 75,000 Btu/h (see 42
U.S.C. 6291(27)(A) and the discussion in section III.A.2.b of this
document).
In the January 2022 NOPR, DOE evaluated feedback from commenters
indicating that most aspects of the test methods in ASHRAE 118.2-2022
\41\ were still applicable outside of its formal scope of coverage. 87
FR 1554, 1568 (Jan. 11, 2022). In the January 2022
[[Page 40426]]
NOPR, DOE stated that it has found through testing that models with
rated storage volumes above 120 gallons or that can deliver water above
180 [deg]F can be tested to DOE's appendix E test procedure, and, given
the similarities between the currently applicable DOE test procedure
and ASHRAE 118.2-2022, DOE tentatively determined that such models
could also be tested using the methods in the ASHRAE test standard. Id.
DOE did not receive any comments in response to this tentative
conclusion in the January 2022 NOPR. Therefore, in evaluating the
provisions within ASHRAE 118.2-2022, DOE has determined that its test
methods remain applicable to all consumer water heaters and
residential-duty commercial water heaters within the scope of appendix
E (with the exception of low-temperature water heaters). As proposed in
the January 2022 NOPR, this final rule makes several amendments to
appendix E to harmonize with new provisions in ASHRAE 118.2-2022.
Additionally, DOE determined that methods specified in annex B of
ASHRAE 118.2 were applicable to the associated test procedures of this
rulemaking, and, therefore, the Department has incorporated by
reference ASHRAE 118.2-2022 for use in appendix E, with annex B being
the directly applicable provision.
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\41\ ASHRAE 118.2-2022 was published on January 24, 2022, which
was after the January 2022 NOPR was published in the Federal
Register on January 11, 2022; thus, the NOPR only discusses public
review drafts of ASHRAE 118.2-2022 which were available at the time.
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b. Provisions in ASHRAE 118.2-2022 Being Addressed by DOE
Thermal Break
ASHRAE 118.2-2022 specifies the use of a ``thermal break'' in the
test set-ups shown for free-standing water heaters and water heaters
supplied with a countertop enclosure (see Figures 1, 2, 3, 6, 7, 8, and
9 of ASHRAE 118.2-2022). A thermal break is optional in the ASHRAE
118.2-2022 test set-ups shown for wall-mounted water heaters (see
Figures 4 and 5 of ASHRAE 118.2-2022).
ASHRAE 118.2-2022 defines a ``thermal break'' in section 3 as a
nipple made of material that has thermal insulation properties (e.g.
plastics) to insulate the bypass loop from the inlet piping. It should
be able to withstand a pressure of 150 psi (1.034 MPa), and a
temperature greater than the maximum temperature the water heater is
designed to produce. A thermal break is added to the test set-up to
prevent heat from traveling up the inlet piping into a bypass line, if
one is utilized. (ASHRAE 118.2-2022 requires a bypass line to be
installed, whereas the existing appendix E test procedure does not.)
When purging the inlet piping before a draw, any heat that is
transferred from the water heater through the inlet piping to the
bypass line section would be lost, as the bypass line is replenished
with cold supply water. The thermal break helps to prevent this heat
loss.
In this rulemaking, DOE has sought feedback from stakeholders in
the April 2020 RFI as to whether a thermal break should be required in
the DOE test procedure regardless of whether a bypass line is used, and
additionally, whether DOE should adopt a definition for this set-up
component. 85 FR 21104, 21110 (April 16, 2020). The January 2022 NOPR
discussed the mixed comments received on this topic. In summary, three
commenters stated that a thermal break should be included in the test
set-up regardless of whether there is a bypass or purge line; however,
three others (including a testing standards organization, CSA Group)
stated that a thermal break is not needed if no bypass or purge loop is
present. Several commenters indicated that a standardized definition
for a ``thermal break'' would be beneficial for repeatability of the
test procedure. 87 FR 1554, 1569 (Jan. 11, 2022).
In the January 2022 NOPR, DOE explained that a bypass line is a
method that test laboratories use to ensure inlet water temperatures
are within the bounds of the test procedure (i.e., within 58 [deg]F
2 [deg]F by the first measurement of the draw), but its
inclusion in the test set-up can create a condition whereby a constant
low temperature can remove energy from the water heater at a higher
rate than would be removed in the field. Because a bypass line is not
the only approach to maintaining inlet conditions, DOE had tentatively
determined that requiring a thermal break (and providing a definition
for this component) would not be necessary. Id.
BWC responded by indicating that it is not aware of any
manufacturer or test laboratory omitting the use of a thermal break,
and, therefore, DOE should adopt a definition for ``thermal break'' to
ensure consistent results from laboratory to laboratory. The commenter
recommended that a thermal break should be defined as ``a plastic and
thermally non-conductive material that can withstand a minimum
temperature of 150 [deg]F.'' BWC also stated that its testing indicated
that when a bypass line (also known as a ``purge loop'') is used, all
temperatures more consistently met the tolerance criteria in appendix
E; furthermore, test results were more often out of tolerance when a
bypass line was not used. BWC argued that as a result, use of a bypass
line will remain common practice, and as such, thermal breaks will also
continue to be used. (BWC, No. 33 at p. 3)
DOE has considered the comments received on this topic throughout
this rulemaking, and, although DOE maintains that a thermal break would
not be needed in all set-up cases, the Department has concluded that
there is overwhelming support for establishing a standardized
definition for ``thermal break.'' In order to address concerns
regarding the repeatability of the test procedure (i.e., various
facilities maintaining a consistent set-up approach), DOE is adopting a
definition for this component consistent with that in section 3 of
ASHRAE 118.2-2022, but with minor modification. Specifically, DOE is
defining ``thermal break'' as ``a thermally non-conductive material
that can withstand a pressure of 150 psi (1.034 MPa) at a temperature
greater than the maximum temperature the water heater is designed to
produce and is utilized to insulate a bypass loop, if one is used in
the test set-up, from the inlet piping.'' However, DOE is not requiring
the use of a bypass loop or a thermal break in this final rule. DOE
reasons that providing a definition for a thermal break will improve
consistency in test set-ups when the testing agency opts to use a
bypass loop with a thermal break.
FHR Test Flow Rates
Section 7.3.3.1 of ASHRAE 118.2-2022 indicates that the flow rate
for non-flow-activated water heaters with rated storage volumes less
than 20 gallons would be 1.5 0.25 gallons per minute (gpm)
(5.7 0.95 liters (L)/minute (min)) when conducting the FHR
test. Section 5.3.3, ``First-Hour Rating Test,'' of appendix E requires
that water heaters with a storage volume less than 20 gallons be tested
at 1.0 0.25 gpm (3.8 0.95 L/min). These flow
rates are lower than the 3.0 0.25 gpm (11.4
0.95 L/min) required for water heaters with rated storage volumes
greater than or equal to 20 gallons. Water heaters with low rated
storage volumes (less than 20 gallons) and high input rates can
potentially operate indefinitely (i.e., instantaneously) at even the
3.0 0.25 gpm (11.4 0.95 L/min) flow rate.
Therefore, when such products are tested as currently required by
appendix E, the measured FHR is near the maximum possible value of 60
gallons (227 L) \42\ and, as a result, these
[[Page 40427]]
products would be required to use the medium draw pattern according to
Table I of appendix E. However, as discussed in the January 2022 NOPR,
these models could be used in applications similar to water heaters
that are required to test using the high draw pattern, and the existing
method of testing these products may not best represent how they are
used in the field. Instead, DOE finds that a flow rate of 1.5 0.25 gpm (5.7 0.95 L/min)--as introduced in ASHRAE
118.2-2022--would be sufficient to allow these products to be tested
and rated in the high draw pattern. 87 FR 1554, 1569-1570 (Jan. 11,
2022).
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\42\ At 1.0 0.25 gallons per minute during the 60-
minute first-hour rating test, the maximum possible delivery
capacity is 1.0 gallon per minute x 60 minutes = 60 gallons. At 1.5
0.25 gallons per minute during the 60-minute first-hour
rating test, the maximum possible delivery capacity is 1.5 gallon
per minute x 60 minutes = 90 gallons.
---------------------------------------------------------------------------
In this rulemaking, DOE has sought information from commenters
regarding the flow rate for the FHR test of non-flow-activated water
heaters with rated storage volumes less than 20 gallons. DOE has also
participated in the public review of ASHRAE 118.2 prior to the 2022
edition being released, leading up to the establishment of the 1.5
0.25 gpm (5.7 0.95 L/min) flow rate criteria
for these products during the FHR test. DOE also performed testing on
three electric storage water heaters less than 20 gallons to both the
then currently applicable appendix E and ASHRAE 118.2-2022 flow rates
and provided these test data in the January 2022 NOPR. The results
indicated that changing the flow rate during the FHR test for water
heaters with a rated storage volume less than 20 gallons from 1.0
0.25 gpm (3.8 0.95L/min) to 1.5
0.25 gpm (5.7 0.95 L/min) would have a relatively minimal
impact on the FHR for water heaters with low input rates. For models
with high input rates, the change in flow rate could significantly
increase the FHR and result in some models being tested and rated for
UEF using a higher draw pattern, which would provide ratings that are
more representative of their actual use. Therefore, DOE proposed to
adopt the higher flow rate of 1.5 0.25 gpm (5.7 0.95 L/min) for the FHR test of non-flow-activated water heaters
with rated storage volumes less than 20 gallons. 87 FR 1554, 1570 (Jan.
11, 2022).
In response, AHRI indicated that the revised flow rate of 1.5 gpm
may not be appropriate for models as small as 2 gallons, for which the
proposed change could yield unrepresentative results for FHR. (AHRI,
No. 40 at p. 4) AHRI also raised concerns about the accuracy of flow
rates for smaller capacity water heaters. (AHRI, Jan. 27, 2022 Public
Meeting Transcript, No. 27 at p. 41) Rheem generally supported DOE's
proposal to align with ASHRAE 118.2-2022 on this issue. However, Rheem
pointed out that the test data provided in the NOPR reflected consumer
water heaters in only the very small draw pattern, so Rheem requested
DOE to provide further test data and also to conduct testing on
products near the division between the very small and low draw
patterns. Rheem stated that a change in draw pattern will affect the
UEF rating and will need to be taken into account. (Rheem, No. 31 at p.
2)
In response to the concerns raised by AHRI, DOE notes that its test
data presented in the January 2022 NOPR were taken from samples in the
very small draw pattern (see 87 FR 1554, 1570 (Jan. 11, 2022)). DOE has
additionally provided the storage volumes of the products which were
tested in Table III.1 of this final rule. The samples were all
approximately 2 gallons in storage volume, and the 1.5 gpm flow rate
was found to be sufficiently representative for these products (the
absolute value of the largest percent difference was less than 5
percent). Additionally, as stated in the January 2022 NOPR, the
increase in flow rate did not cause any of these products to move from
the very small draw pattern to the low draw pattern, which resolves a
chief concern regarding the representativeness of the FHR results. Id.
In response to Rheem's requests for additional data, DOE was not able
to identify non-flow-activated water heaters less than 20 gallons
closer to 18 gallons of FHR--the division between the very small and
low draw patterns--in order to perform testing on such products.
However, while the net average change may approximately be a 2-percent
increase in FHR rating, DOE has determined that the increased flow rate
will allow products to be rated in more representative draw patterns,
as discussed earlier in this section.
Table III.1--Average First-Hour Rating Based on a Flow Rate of 1.0 gpm and 1.5 gpm
----------------------------------------------------------------------------------------------------------------
Measured
storage Average FHR * at 1.0 Average FHR * at 1.5
Unit No. volume, gpm (3.8 L/min), gpm (5.7 L/min), Change %
gallons gallons gallons
----------------------------------------------------------------------------------------------------------------
1................................. 2.4 7.3 (Very Small)..... 7.5 (Very Small)..... +3.4
2................................. 2.4 6.4 (Very Small)..... 6.2 (Very Small)..... -2.2
3................................. 1.8 6.9 (Very Small)..... 7.2 (Very Small)..... +4.7
Net Average................... .............. ..................... +2.0.................
----------------------------------------------------------------------------------------------------------------
* FHR results are rounded to the nearest 0.1 gallon and reflect the arithmetic mean of four trials per water
heater.
In this final rule, DOE is amending section 5.3.3.1 of the appendix
E test procedure to require a flow rate of 1.5 0.25 gpm
(5.7 0.95 L/min) when conducting the FHR test on non-flow-
activated water heaters with rated storage volumes less than 20
gallons.
24-Hour Simulated-Use Test First Recovery Period
The first recovery period of the 24-hour simulated-use test is used
in section 8.3.2 of ASHRAE 118.2-2022 and section 6.3.2 of appendix E
to calculate recovery efficiency. Section 8.3.2 of ASHRAE 118.2-2022
specifies that, when the first recovery of the 24-hour simulated-use
test ends during a draw, the first recovery period extends until the
end of that draw, whereas DOE's test procedure does not explicitly
address how to calculate recovery efficiency if the first recovery
period ends during a draw.
A ``recovery period'' is defined in section 1 of appendix E as
``the time when the main burner of a storage water heater is raising
the temperature of the stored water.'' Each of the parameters in the
current recovery efficiency equation in section 6.3.2 of appendix E is
recorded from the ``beginning of the test to the end of the first
recovery period following the first draw.'' The currently applicable
appendix E test procedure does not explicitly state whether values are
recorded at the end of the recovery period that ends after the
initiation of the first draw, or at the end of a recovery period that
occurs after the end of the first draw.
In the January 2022 NOPR, DOE noted that the situation in which a
recovery ends during a draw likely occurs during draws with a low
enough flow rate that the water heater can heat water more
[[Page 40428]]
quickly than the draw is removing. 87 FR 1554, 1574 (Jan. 11, 2022).
DOE also explained that the energy used for the recovery efficiency
calculation includes energy used to heat water and auxiliary energy;
therefore, the energy associated with the first recovery period should
represent the entire draw to capture all energy use. Id.
On January 31, 2020, DOE published in the Federal Register a Notice
of Decision and Order \43\ (Decision and Order) by which a test
procedure waiver for certain basic models was granted to address the
issue of a second recovery initiating during the draw during which the
first recovery ended. 85 FR 5648. The Decision and Order prescribes an
alternate test procedure that extends the first recovery period to
include both the first and second recoveries. Id. at 85 FR 5652. In the
context of the Decision and Order, DOE determined that the
consideration of delivered water mass and inlet and outlet temperatures
until the end of the draw is appropriately representative, and,
therefore, the entire energy used from both recoveries is included. Id.
at 85 FR 5651-5652.
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\43\ Notice of Decision and Order in response to BWC petition
for waiver is available at: www.regulations.gov/document?D=EERE-2019-BT-WAV-0020-0008.
---------------------------------------------------------------------------
In the January 2022 NOPR, after considering comments received in
response to the April 2020 RFI, DOE proposed to establish a new
provision that states that when the first recovery ends during a draw,
the first recovery period is extended to the end of the draw and the
mean tank temperature measured immediately after cut-out is used as the
maximum mean tank temperature value in the recovery efficiency
calculation. 87 FR 1554, 1574 (Jan. 11, 2022). In addition, DOE
proposed to update the recovery efficiency equation to specify
accounting for the mass of water drawn for all draws initiated during
the recovery period. DOE noted that such a change would be consistent
with the published Notice of Decision and Order and was supported by
commenters. Id.
In response, BWC stated the proposed updates to the overall test
procedure provide a more accurate calculation of recovery efficiency
and eliminate situations where products would be disadvantaged for
completing their recovery in the middle of a draw, thereby providing a
more representative measurement of a product's overall energy
efficiency. (BWC, No. 33 at pp. 5-6)
DOE did not receive any other comments in response to these
proposals. As such, DOE is amending appendix E to adopt the proposals
from the January 2022 NOPR, which are consistent with the alternate
test procedure in the Decision and Order and in ASHRAE 118.2-2022.
24-Hour Simulated-Use Test Final Hour
Although not stated explicitly in section 5.4.2 of the currently
applicable appendix E, in the case that the standby period is between
the first and second draw clusters, power to the main burner, heating
element, or compressor is disabled during the last hour of the 24-hour
simulated-use test. In the case that the standby period is after the
last draw of the 24-hour simulated-use test, power to the main burner,
heating element, or compressor is not disabled. Section 5.4.2 of the
currently applicable appendix E states that during the last hour of the
24-hour simulated-use test, power to the main burner, heating element,
or compressor shall be disabled; at 24 hours, record the reading given
by the gas meter, oil meter, and/or the electrical energy meter as
appropriate; and determine the fossil fuel and/or electrical energy
consumed during the entire 24-hour simulated-use test and designate the
quantity as Q. Section 5.4.2 of the currently applicable appendix E
also provides that in the case that the standby period is after the
last draw of the 24-hour simulated-use test, an 8-hour standby period
is required, and this period may extend past hour 24. The procedures
for the standby period after the last draw of the 24-hour simulated-use
test allow for a recovery to occur at the end of the 8-hour standby
period, which indicates that the power to the main burner, heating
element, or compressor is not disabled. DOE's procedure, as described,
may result in some confusion. Further, the method of determining the
total energy use during the 24-hour simulated-use test, Q, and total
test time are not explicitly stated for when a standby period occurs
after the last draw of the 24-hour simulated-use test. As discussed in
the following paragraphs, DOE is amending the procedures for the last
hour of the 24-hour simulated-use test, consistent with its proposals
in the January 2022 NOPR, to explain how to end the test for both
standby period scenarios, and this amendment aligns with the updated
approach in ASHRAE 118.2-2022.
In ASHRAE 118.2-2022, power is not disabled when the standby period
occurs after the last draw of the test. However, if a recovery occurs
between an elapsed time of 23 hours following the start of the test
(hour 23) and 24 hours following the start of the test (hour 24), the
following alternate approach is applied to determine the energy
consumed during the 24-hour simulated-use test: The time, total energy
used, and mean tank temperature are recorded at 1 minute prior to the
start of the recovery occurring between hour 23 and hour 24, along with
the average ambient temperature from 1 minute prior to the start of the
recovery occurring between hour 23 and hour 24 to hour 24 of the 24-
hour simulated-use test. These values are used to determine the total
energy used by the water heater during the 24-hour simulated-use test.
This alternate calculation combines the total energy used 1 minute
prior to the start of the recovery occurring between hours 23 and 24
and the standby loss experienced by the tank during the time between
the minute prior to the recovery start and hour 24. This provision in
section 7.4.3.2 of ASHRAE 118.2-2022 does not require the water heater
to be de-energized during the standby period. Disabling power to the
water heater is typically a manual operation that requires the presence
of a technician. In cases where the technician does not disable power
at the correct time, a retest of the 24-hour simulated-use test may be
necessary. To the extent this provision would eliminate the need to
ensure that a unit is switched off for the last hour of the 24-hour
simulated-use test, it could reduce test burden.
In the January 2022 NOPR, after considering comments on the April
2020 RFI, DOE tentatively concluded that further evaluation of the
alternate procedure presented in the March 2019 ASHRAE Draft 118.2 and
April 2021 ASHRAE Draft 118.2 should be conducted before a
determination is made on whether DOE should adopt such changes.
However, DOE also tentatively determined that the procedure for the
last hour of the 24-hour simulated-use test would benefit from further,
more explicit instruction, and, thus, DOE proposed to explicitly state
how to end the test depending on whether the standby period is between
draw clusters 1 and 2 or after the last draw of the test. 87 FR 1554,
1575 (Jan. 11, 2022).
No comments or data were received on this topic in response to the
January 2022 NOPR or July 2022 SNOPR.
As such and for the reasons previously stated, DOE is finalizing
its proposal from the January 2022 NOPR to clarify how to end the test
depending on when the standby period occurs. DOE will continue to
evaluate the impacts of fully adopting the ASHRAE 118.2-2022 method and
may consider that in a future test procedure rulemaking for the subject
water heaters.
[[Page 40429]]
As discussed in section III.E.4 of this document, DOE is dividing
section 5.4.2 of appendix E into two sections: section 5.4.2.1, ``Water
Heaters that Can Have Internal Storage Tank Temperature Measured
Directly,'' and section 5.4.2.2, ``Water Heaters that Cannot Have
Internal Storage Tank Temperature Measured Directly.'' The new section
5.4.2.1 of appendix E provides specific direction on the measurements
to be taken if the standby period occurs at the end of the first
recovery period after the last draw of the 24-hour simulated-use test.
These revised instructions for the final hour of the 24-hour simulated-
use test also no longer require disabling the water heater for the
standby mode, a change which harmonizes with the procedure in ASHRAE
118.2-2022. DOE has determined that these provisions are appropriate
only for water heaters that can have internal storage tank temperatures
measured directly, because these steps require recording the mean tank
temperature at various points during the final hour. For water heaters
that cannot have internal storage tank temperatures measured directly,
DOE is adopting an alternative method entirely (discussed in section
III.E.7 of this document) which requires a standby period after the
final draw and temperature measurements made via estimation.
c. Other Updates
Inlet Water Temperature Measurement Location
In its review of the ASHRAE 118.2-2022 set-up figures, DOE
determined that the placement of the inlet water temperature
measurement probe differs between ASHRAE 118.2-2022 and the currently
applicable appendix E. In ASHRAE 118.2-2022, the inlet water
temperature is always measured on the upstream side of the heat trap
formed by the U-bend in the required piping, whereas the figures in
appendix E vary this location (i.e., either on the upstream side or on
the downstream side of the U-bend) depending on the type of water
heater being tested.
DOE requested information about the potential impact of this
measurement location on energy efficiency results in the January 2022
NOPR. 87 FR 1554, 1569 (Jan. 11, 2022).
On this topic, BWC stated there are inconsistencies in the
placement of inlet thermocouples in the set-up figures currently shown
in appendix E. BWC suggested adopting the figures in ASHRAE Standard
118.2, as they are representative of most set-ups and illustrate
placement of the inlet thermocouples on the upstream side of the U-bend
in all instances. BWC also more generally urged DOE to adopt the water
heater test set-up figures adopted in ASHRAE 118.2-2022, stating that
it is not aware of any testing laboratory that does not utilize the
set-ups depicted in these figures. (BWC, No. 33 at pp. 2-3) (DOE
understands the ``inconsistencies'' mentioned by BWC as referring to
the differences in temperature probe placement for different types of
water heaters, as mentioned at the beginning of this subsection.)
AET indicated that there may be problems with the location and
orientation of the bypass (purge) line connection in the ASHRAE 118.2-
2022 test set-ups when testing small water heaters (i.e., electric
instantaneous water heaters). The commenter claimed that without a
bypass line installed at the water inlet, it is not possible to meet
the test conditions and tolerances for the inlet water temperature
during test draws when the measurement location is as specified in the
current appendix E test procedure. AET explained that the location of
the bypass line combined with the rest of the piping configuration for
measuring inlet water temperature can induce a small amount of flow in
the piping near the inlet to the water heater, even when a draw is not
being conducted and there is no flow through the water heater.
According to AET, flow-activated water heaters with especially
sensitive flow sensors could initiate heating upon sensing this ``false
flow,'' and this would in turn cause the energy consumption under test
to increase in an unrepresentative manner. AET provided a detailed
description of this phenomenon in its public comment and stated that
its claims were substantiated by review of recent test data, though
these data were not provided to DOE. AET suggested that one potential
solution to the identified problem could be to move the connection
point of the purge line and the inlet measurement location further from
the water heater. In addition, AET suggested adjusting the various pipe
T-junctions and their orientations such that the momentum of a cold-
water purge will be directed horizontally away from the pipe direction
going to the water heater and not induce a false flow, with the
commenter opining that this change could be implemented for all types
of water heaters. (AET, No. 29 at pp. 6-9)
As discussed in the January 2022 NOPR, maintaining the same inlet
water temperature measurement location for all water heater types
((i.e., harmonizing with ASHRAE 118.2-2022)) would simplify the test
set-up as compared to the requirements of the currently applicable
appendix E. However, DOE did not have sufficient information at the
time to propose such harmonization. 87 FR 1554, 1568-1569 (Jan. 11,
2022).
In the January 2022 NOPR, DOE noted that use of a bypass loop is
not the only possible test set-up for meeting the test conditions
within appendix E. 87 FR 1554, 1569 (Jan. 11, 2022). However, based on
the comment from BWC, DOE understands that many test facilities do use
a bypass loop as a solution to having to stabilize the inlet water
conditions. After considering the comments from AET and BWC, DOE has
determined that laboratories are likely to continue to use bypass lines
regardless of the placement of the inlet water temperature measurement,
because a bypass line is simple to install and relatively low-cost. If
this occurs, then there is a risk that UEF ratings for certain flow-
activated water heaters with highly sensitive sensors may be lower due
to the additional energy consumption of the water heater when a false
flow is sensed. DOE is not incorporating the updates found in the
ASHRAE 118.2-2022 figures. Instead, DOE is maintaining the current set-
up directions for inlet water temperature measurement in appendix E
and, which will allow for the continued use of a bypass line when
necessary and appropriate. Regarding AET's concerns about the location
of the bypass loop for certain electric instantaneous water heaters,
DOE notes that it has not observed the issue in any of its testing.
Further, DOE is not adopting the figures in ASHRAE 118.2-2022, so,
therefore, the Department is not specifying the location of the bypass
loop in its test set-up. Accordingly, during testing, there will be
sufficient flexibility to locate the bypass line, when necessary, in a
location that results in representative operation and performance of
the unit under test.
FHR Test Initiation Criteria
ASHRAE 118.2-2022 includes additional criteria defining the start
of the FHR test as compared to DOE's test procedure at appendix E.
These differences are briefly explained in the following paragraphs.
Section 5.3.3.3 of the currently applicable appendix E states that
prior to the start of the FHR test, if the water heater is not
operating (i.e., heating water), initiate a draw until cut-in \44\
[[Page 40430]]
(i.e., when the water heater begins heating water). The draw is then
terminated any time after cut-in, and the water heater is operated
until cut-out.\45\ Once the maximum mean tank temperature is observed
after cut-out, the initial draw of the FHR test begins.
---------------------------------------------------------------------------
\44\ ``Cut-in'' is defined in section 1 of appendix E as ``the
time when or water temperature at which a water heater control or
thermostat acts to increase the energy or fuel input to the heating
elements, compressor, or burner.''
\45\ ``Cut-out'' is defined in section 1 of appendix E as ``the
time when or water temperature at which a water heater control or
thermostat acts to reduce to a minimum the energy or fuel input to
the heating elements, compressor, or burner.''
---------------------------------------------------------------------------
Section 7.3.3.3 of ASHRAE 118.2-2022 specifies that the draw
preceding the initial draw of the FHR test must proceed until the
outlet temperature drops 15 [deg]F below the maximum outlet temperature
observed, or until a draw time limit \46\ is reached. If the draw time
limit is reached before the outlet temperature drops 15 [deg]F below
the maximum outlet temperature observed, then the main heating source
of the water heater is shut off, and the draw is continued until the
outlet temperature has dropped 15 [deg]F below the maximum outlet
temperature. Requiring the outlet temperature to drop 15 [deg]F below
the maximum outlet temperature may provide a more consistent starting
condition for the FHR test compared to the pre-conditioning method
specified in the currently applicable DOE test procedure because draws
of varying lengths can create different internal tank temperature
profiles.
---------------------------------------------------------------------------
\46\ The draw time limit is the rated storage capacity divided
by the flow rate times 1.2 (i.e., for a 75-gallon water heater the
draw time limit would be 30 minutes, or 75 gallons divided by 3 gpm
times 1.2).
---------------------------------------------------------------------------
Thus, in the January 2022 NOPR, DOE tentatively determined that the
additional requirement to tie the length of the initial draw to a
specific outlet temperature (which in some cases would extend the draw
length as compared to the currently applicable DOE test procedure)
could increase the repeatability of the FHR test. 87 FR 1554, 1570-1571
(Jan. 11, 2022). However, DOE also argued that, with both the ASHRAE
118.2-2022 and appendix E initiation criteria, the water heater can be
considered ``fully heated'' and to have similar internal energy content
before beginning the FHR test, although differences may be present due
to the internal water temperature gradient throughout the tank. DOE did
not propose an amendment to include pre-FHR test conditioning, because
it was unclear how these differences in internal tank temperature would
affect the test results. 87 FR 1554, 1571 (Jan. 11, 2022).
In response, A.O. Smith stated that the 15 [deg]F initiation
criterion and the additional specificity on draw termination in ASHRAE
118.2 would improve consistency and repeatability and would not
conflict with the currently applicable DOE test procedure, and,
therefore, those provisions should be adopted. (A.O. Smith, No. 37 at
pp. 6-7) BWC also urged DOE to consider adopting the pre-FHR pre-
conditioning requirements specified in ASHRAE 118.2. BWC stated that
the specifications in ASHRAE 118.2 only add parameters to achieve
better testing consistency, and that the currently applicable test
procedure may frequently yield inconsistencies from short pre-draws
prior to the initiation of the FHR test, thereby causing storage water
heaters to be unable to meet the test procedure's 125 [deg]F 5 [deg]F requirement. BWC stated that changes to the pre-FHR
preconditioning requirements were agreed to by manufacturers during the
development of ASHRAE 118.2, and that manufacturers are prepared to
undertake the burden of any re-testing in favor of a more robust test
method. (BWC, No. 33 at pp. 4-5)
In response, DOE notes that commenters did not indicate the impact
of this change on rated values of products nor did they provide any
data in that regard. Additionally, DOE is not aware of storage water
heaters which are not able to meet the 125 [deg]F 5 [deg]F
outlet temperature requirement, but if this is demonstrated to be a
problem, the Department would address the impacted products in a future
rulemaking once more data are collected. Although the Department
acknowledges the potential benefits to consistency and repeatability
that may accompany a pre-FHR preconditioning requirement, without a
clear understanding of the associated impact on ratings, DOE is not
adopting this change to the Federal test procedure at this time.
Additionally, DOE notes that the draw time limit in section 7.3.3.3
of ASHRAE 118.2-2022 is a function of the ``nominal'' capacity of the
water heater (in gallons or liters). Nominal capacity is typically not
equal to the rated storage volume, and there is no standardized
methodology in appendix E or in ASHRAE 118.2-2022 to determine nominal
capacity; hence, there is a concern that the draw time limits could be
different for two identical water heaters labeled at two different
nominal capacities. If DOE were to adopt the essence of the initiation
criteria in ASHRAE 118.2-2022, DOE would consider substituting
``nominal capacity'' for ``rated storage volume'' (because rated
storage volume is a standardized metric with a test method associated
with it in section 5.2.1 of appendix E). This deviation could cause
additional testing costs for manufacturers.
For these reasons, DOE is maintaining the FHR test initiation
criteria currently found in appendix E, which provide that the
preconditioning draw can be terminated any time after cut-in, and the
water heater is operated until cut-out. Once the maximum mean tank
temperature is observed after cut-out, the initial draw of the FHR test
begins.
24-Hour Simulated-Use Test Initiation Criteria
Similar to the initiation criteria discussed in the previous
section for the FHR test, section 7.4.2 of ASHRAE 118.2-2022 includes
criteria for a pre-24-hour simulated-use test draw, which ends after
either the outlet temperature drops by 15 [deg]F or the draw time limit
is reached. Section 5.4.2 of the currently applicable appendix E
requires that the water heater sit idle for 1 hour prior to the start
of the 24-hour simulated-use test, during which time no water is drawn
from the unit and no energy is input to the main heating elements, heat
pump compressor, and/or burners. Appendix E provides no instruction on
how to condition the tank prior to this one hour. However, as discussed
in the previous section, it remains unclear how the outlet temperature
drop criteria and the draw time limit will affect the internal tank
temperature at the start of the 24-hour simulated-use test and how this
difference in internal tank temperatures will affect the test results.
In the January 2022 NOPR, DOE did not propose to amend appendix E
to include the April 2021 ASHRAE Draft 118.2 24-hour simulated-use test
initiation criteria (which was substantially the same as the 24-hour
simulated-use test initiation criteria included in ASHRAE 118.2-2022)
and invited comment and data that provide information on the impact of
this update on UEF results. 87 FR 1554, 1573 (Jan. 11, 2022).
On this topic, BWC argued that the initiation criteria in ASHRAE
Standard 118.2 should also be adopted for the 24-hour simulated-use
test so as to improve the repeatability and reproducibility of the test
procedure. (BWC, No. 33 at pp. 4-5) DOE considered this comment, as
well as those received regarding the FHR test initiation criteria, and
has determined that it still lacks the necessary data that would
provide a clear understanding of the impact that this update would have
on ratings. Accordingly, for the same reasons stated in the previous
section, DOE is not adopting this change in this final rule.
[[Page 40431]]
FHR Test Termination Temperature
Section 7.3.3.4 of ASHRAE 118.2-2022 includes additional criteria
regarding water draws during the FHR test, as compared to the current
DOE test procedure. The FHR test required in section 5.3.3 of appendix
E specifies a series of water draws over the course of one hour. After
each water draw is initiated, the draw is terminated when the outlet
water temperature decreases 15 [deg]F from the maximum outlet water
temperature measured during the draw. For example, if after initiating
a water draw, the outlet water temperature reaches a maximum
temperature of 125 [deg]F, the water draw would continue until the
outlet water temperature drops to 110 [deg]F, at which time the water
draw would be terminated. Similar to the public review drafts of ASHRAE
118.2, section 7.3.3.4 of ASHRAE 118.2-2022 specifies that water draws
during the FHR test terminate if either: (1) The outlet water
temperature decreases by the quantity of nominal delivery temperature
minus 110 [deg]F from the maximum outlet water temperature \47\ or (2)
the outlet water temperature decreases to 105 [deg]F, regardless of the
maximum outlet water temperature measured during the draw. Setting a
minimum temperature threshold of 105 [deg]F would reflect that, in
practice, consumers would likely stop drawing water when it gets below
105 [deg]F, as the water would no longer be considered ``hot.''
---------------------------------------------------------------------------
\47\ The nominal delivery temperature in section 2.4 of the
appendix E test procedure is 125 [deg]F, and 125 [deg]F-110 [deg]F =
15 [deg]F. Thus, for a nominal delivery temperature of 125 [deg]F,
ASHRAE 118.2-2022 and the DOE test procedure both use a 15 [deg]F
drop to indicate when the draw must be terminated.
---------------------------------------------------------------------------
A temperature of 105 [deg]F would be the FHR test termination
temperature if the maximum outlet temperature were 120 [deg]F (a 15
[deg]F difference) as per the current DOE test procedure. 120 [deg]F is
the lower end of the outlet temperature tolerance band specified in
section 5.2.2.2 of appendix E (i.e., 125 [deg]F 5 [deg]F).
However, as discussed in section III.A.4.b of this document, there
exist low-temperature water heaters that are not capable of maintaining
these temperatures when tested to the flow rates required in section
5.2.2.2 of appendix E, and this raises the question of whether a
criterion for ending a draw when the outlet temperature reaches 105
[deg]F would be representative for all consumer water heaters and
residential-duty commercial water heaters.
In this rulemaking, DOE sought information and feedback from
stakeholders on the potential impacts and implications of setting an
FHR test termination temperature such as 105 [deg]F. In particular, DOE
was interested in data which would determine the representativeness of
a 105 [deg]F minimum temperature based on consumer use and
expectations. 85 FR 21104, 21109 (April 16, 2020). While several
stakeholders generally supported the use of a termination temperature,
two manufacturers indicated that more testing and investigation are
necessary prior to adopting this. 87 FR 1554, 1571, 1572 (Jan. 11,
2022). In commenting on the April 2020 RFI, Rheem suggested 100 [deg]F
instead to account for low-temperature water heaters. (Rheem, No. 14 at
p. 3) In the January 2022 NOPR, DOE tentatively determined that, based
on a review of existing test data, the 105 [deg]F termination
temperature criterion would affect only a small number of tests, if
any. Additionally, DOE noted that Rheem's suggested 100 [deg]F
termination temperature would most likely not be representative for all
types of consumer water heaters and residential-duty commercial water
heaters. Given the need for further evaluation of the specific
termination temperature and its potential impacts, DOE did not propose
to adopt a termination temperature for the FHR test in the January 2022
NOPR. 87 FR 1554, 1572 (Jan. 11, 2022).
In response to the January 2022 NOPR, BWC reiterated that DOE
should include the 105 [deg]F termination temperature established in
ASHRAE Standard 118.2 to provide additional clarity and reflect
representative usage. (BWC, No. 33 at p. 4) However, commenters did not
provide additional data or consumer usage information to indicate
whether 105 [deg]F is representative of the minimum delivery
temperature consumers generally expect. DOE was likewise unable to
obtain widespread field use data on its own initiative.
As of this final rule, there remains significant uncertainty
regarding what the value of the termination temperature should be. As
noted previously, Rheem indicated 100 [deg]F should be used to account
for low-temperature water heaters. Section 7.3.3.4 of ASHRAE 118.2-2022
uses a 105 [deg]F minimum termination temperature, which was
recommended by several stakeholders. DOE did not receive, nor has DOE
found, any additional data regarding the minimum delivery temperature
consumers would generally expect. However, should the water heater
provide a maximum delivery temperature during the test which is lower
than 120 [deg]F (which may potentially occur even if the unit's
controls are adjusted properly according to section 5.2.2 of appendix
E), a 15 [deg]F temperature drop would result in termination below 105
[deg]F. DOE expects this would impact a relatively small number of
units, but at this time, there is inadequate test data to indicate how
frequently this may occur, which types of products would be affected,
and how they would be affected by a specific termination temperature.
Given these considerations, DOE is not adopting a minimum
termination temperature for the FHR test in this rulemaking.
FHR Test Final Draw Volume
Section 5.3.3.3 of appendix E includes a provision for the FHR test
requiring that if the final draw is not initiated prior to one hour
from the start of the test, then a final draw is imposed at the elapsed
time of one hour. In this situation, calculations presented in section
6.1 of appendix E are used to determine the volume drawn during the
final draw for purposes of calculating FHR. The volume of the final
draw is ``scaled'' based on the temperature of the water delivered
during the final draw as compared to the temperature of the water
delivered during the previous draw to account for the water removed in
the final draw being at a lower temperature than previous draws. The
scaled final draw volume is added to the total volume drawn during the
prior draws to determine the FHR. ASHRAE 118.2-2022 does not include a
final draw volume scaling calculation for the case in which a draw is
not in progress at one hour from the start of the test and a final draw
is imposed at the elapsed time of one hour. Instead, the ASHRAE 118.2-
2022 method calculates FHR as the sum of the volume of hot water
delivered giving full credit to the final draw.
The methodology for conducting the FHR test, and in particular the
issue of whether to scale the final draw, was considered by DOE in a
final rule that was published in the Federal Register on May 11, 1998
(the May 1998 Final Rule). 63 FR 25996. In the May 1998 Final Rule, DOE
determined that scaling the final draw volume based on the outlet water
temperature was appropriate and was included to adjust the volume of
the last draw to account for the lower heat content of the last draw
compared to the earlier draws with fully heated water. Id. at 63 FR
25996, 26004-26005.
In the January 2022 NOPR, after considering comments on the April
2020 RFI, DOE proposed not to update the final draw volume provisions
in the FHR test because DOE tentatively determined that scaling the
final draw
[[Page 40432]]
volume based on outlet temperature is more representative of the actual
use in the field. 87 FR 1554, 1573 (Jan. 11, 2022). As discussed in the
January 2022 NOPR, AHRI and individual manufacturers recommended that
DOE remove the scaling calculations to harmonize with ASHRAE 118.2-
2022, indicating that this change would have minimal impact on ratings.
Id. at 87 FR 1572. CSA, however, raised concerns with that approach,
because water is usually tempered by the end user, and the commenter
argued that a water heater that delivers a volume of water at a higher
temperature should not be credited the same as one that delivers
roughly the same volume at a lower temperature. CSA also noted that
removing the scaling of the final draw volume could possibly move water
heaters to a higher draw pattern. Id.
After considering these comments, DOE noted in the January 2022
NOPR that the scaling of the final draw accounts for the possible lower
heat content of the last draw as compared to earlier draws. DOE further
explained that the test procedure specifies a constant flow rate
throughout testing, and, as water is drawn from a typical non-flow-
activated water heater, the water temperature decreases. As the
temperature of the water delivered by the water heater decreases,
mixing valves at the point of use will reduce the amount of cold water
being mixed with the hot water in order to maintain the same delivery
temperature to the consumer. If the water from the water heater is at a
lower temperature, more of this hot water will be required to reach the
correct temperature at the fixture. Thus, DOE tentatively determined
that scaling the final draw volume based on outlet temperature is more
representative of the actual use in the field. 87 FR 1554, 1572-1573
(Jan. 11, 2022). Furthermore, DOE also noted that if the scaling
calculation were removed, many water heaters would have a different FHR
than under the currently applicable appendix E, and some would change
draw pattern bins, which would require retesting for UEF and thereby
increase manufacturer burden. Id.
In response, BWC strongly disagreed with DOE's position that
scaling the final draw based on outlet temperature is representative of
field use. BWC reiterated its earlier comments that scaling should not
be necessary and would potentially lead to unrepeatable test results
depending on the timing of the last draw (e.g., creating the
possibility of two different FHR ratings for the same product). BWC
instead recommended the procedure in ASHRAE Standard 118.2, where the
sum of the volume of hot water delivered is used without scaling the
final draw. BWC argued that this approach would more fairly account for
water heated by the product. (BWC, No. 33 at pp. 4-5)
After considering BWC's comment, DOE maintains that when the final
draw is imposed at the end of the FHR test, scaling the volume of water
drawn by temperature is representative and appropriate. Scaling the
final draw allows FHR to capture the difference in hot water delivery
capacity between water heaters that provide roughly the same amount of
hot water in the final draw, but where one water heater provides water
at a higher temperature than the other. This is appropriate because, as
noted, the water temperature is usually tempered at the fixture to
provide the end user with water at the target outlet temperature. If
the hot water is at a lower temperature, more water is required to
provide the user with water at the target temperature, while less water
would be needed if the water is at a higher temperature. Therefore, DOE
has concluded that it is appropriate for FHR to reflect this difference
in capacity, which would not be accounted for if the scaling
calculation is removed. DOE also notes that, at this time, there is
limited information available to assess the potential impacts of
removing the scaling calculation on UEF and FHR ratings, and as a
result DOE is not amending the appendix E test procedure to include the
full volume of the final draw.
24-Hour Simulated-Use Test Standby Period Duration
Appendix E includes a standby \48\ loss measurement period between
the first and second draw clusters \49\ of the 24-hour simulated use
test. During this time, temperature data is recorded and used to
calculate the standby heat loss coefficient. See section 5.4.2 of
appendix E. Sections 7.4.3.1 and 7.4.3.2 of ASHRAE 118.2-2022 add a
condition that the standby period data can be recorded between the
first and second draw clusters only if the time between the observed
maximum mean tank temperatures after cut-out following the first draw
cluster to the start of the second draw cluster is greater than or
equal to 6 hours. Otherwise, the standby period data would be recorded
after the last draw of the test. This condition would provide a
sufficiently long standby period to determine standby loss, which might
make this calculation more repeatable and the results more
representative of standby losses experienced in an average period of
use. However, this might also cause the test to extend beyond a 24-hour
duration.
---------------------------------------------------------------------------
\48\ ``Standby'' is defined in section 1.12 of appendix E as
``the time, in hours, during which water is not being withdrawn from
the water heater.''
\49\ A ``draw cluster'' is defined in section 1 of appendix E as
``a collection of water draws initiated during the 24-hour
simulated-use test during which no successive draws are separated by
more than 2 hours.'' There are two draw clusters in the very small
draw pattern and three draw clusters in the low, medium, and high
draw patterns.
---------------------------------------------------------------------------
The currently applicable DOE test procedure does not have a 6-hour
minimum for a standby period between the first and second draw clusters
of the 24-hour simulated use test. However, section 5.4.2 of appendix E
states, ``In the event that the recovery period continues from the end
of the last draw of the first draw cluster until the subsequent draw,
the standby period will start after the end of the first recovery
period after the last draw of the simulated-use test, when the
temperature reaches the maximum average tank temperature, though no
sooner than five minutes after the end of this recovery period. The
standby period shall last eight hours, so testing will extend beyond
the 24-hour duration of the simulated-use test.'' As such, DOE does
currently have a minimum standby period duration, but only under the
particular case that there is no opportunity to observe standby
operation between the first draw cluster and the second draw cluster.
In the April 2020 RFI, the Department requested comments on
potentially adding a minimum standby period length of 6 hours and the
associated data collection and calculations. 85 FR 21104, 21110 (April
16, 2020). Commenters were split on the appropriateness of this
amendment, with some stakeholders noting a key concern would be the
extension of the total test period time to over 24 hours in many cases.
87 FR 1554, 1574 (Jan. 11, 2022).
The standby heat loss coefficient (i.e., UA) is the main result
calculated from the data recorded during the standby period. DOE
reviewed its available test data and found that, generally, the standby
period duration has little effect on the UA value, and the UA value in
turn has very little effect on UEF. As discussed in the January 2022
NOPR, UA is used only to adjust the daily water heating energy
consumption to the nominal ambient temperature of 67.5 [deg]F (19.7
[deg]C); given that the ambient temperature range is relatively narrow
(i.e., 65 [deg]F to 70 [deg]F (18.3 [deg]C to 21.1 [deg]C)), the
adjustment has only a minimal impact on the daily water heating
[[Page 40433]]
energy consumption. 87 FR 1554, 1574 (Jan. 11, 2022).
In commenting on the January 2022 NOPR, BWC generally disagreed
with DOE's tentative determination that including a 6-hour standby
period minimum would not significantly impact UEF ratings. BWC also
mentioned that it has experienced difficulty having adequate time to
calculate the standby loss coefficient after the first draw cluster.
Thus, BWC reiterated its support for the methodology in ASHRAE 118.2-
2022 but stated that the company would like time to examine this matter
before commenting further. (BWC, No. 33 at p. 6) BWC did not provide
further comments or data on this topic in response to the July 2022
SNOPR.
Considering that DOE did not receive further comments demonstrating
a quantifiable impact of the standby period length on the UEF, DOE
concludes, as initially presented in the January 2022 NOPR, that based
on its test data, the duration of the standby period does not
significantly impact the UEF result. Therefore, in order to minimize
burden (i.e., total test duration) on manufacturers and laboratories
while still allowing results to be representative, repeatable, and
reproducible, DOE is not amending the appendix E test procedure to
require the standby period to be a minimum of 6 hours in duration.
C. Test Conditions and Tolerances
In the January 2022 NOPR, DOE made a number of proposals to the
test conditions and tolerances that were intended to improve
representativeness, reduce testing burden, and/or harmonize with
industry test methods. 87 1554, 1558-1559 (Jan. 11, 2022). These
proposals included changes to the electric supply voltage tolerance,
ambient condition tolerances, gas supply pressure and manifold pressure
tolerances, and flow rate tolerances for certain water heaters. Id. In
addition, in the July 2022 SNOPR, DOE made supplemental proposals
regarding the tolerance on flow rate during the UEF test for models
with rated storage volumes less than 2 gallons and max GPM less than 1
gallon, and regarding optional test conditions for heat pump water
heaters. 87 FR 42270, 42273 (July 14, 2022). These proposals were
intended to improve repeatability and reproducibility and harmonize
with industry testing practices, respectively. Id.
In response to the January 2022 NOPR proposals, APGA provided
general comments stressing the importance of ensuring accuracy,
repeatability, and reproducibility in a test procedure that is not
unduly burdensome to conduct. (APGA, No. 38 at pp. 1-2) AHRI indicated
its support of DOE's proposals to reduce test burden; specifically,
AHRI supported increasing test tolerances for ambient temperature and
relative humidity, and extending untested provisions to include
electric instantaneous water heaters. (AHRI, Jan. 27, 2022 Public
Meeting Transcript, No. 27 at p. 40)
As previously discussed in section I.A of this final rule, DOE's
efforts are aligned with EPCA requirements to create test procedures
that are representative of average use without being unduly burdensome
to conduct. (42 U.S.C. 6293(b)(3)) Each of the proposed changes to test
conditions and tolerances, along with specific stakeholder comments
received and DOE's responses, are discussed further in the subsections
that immediately follow.
1. Supply Water Temperature Measurements
Section 2.3 of the currently applicable appendix E specifies
maintaining the supply water temperature at 58 [deg]F 2
[deg]F (14.4 [deg]C 1.1 [deg]C). During the 24-hour
simulated-use test, maintaining the supply water temperature within
this range can be difficult at the immediate start of a draw due to the
short time between draw initiation and the first measurement at 5
seconds (with subsequent measurements every 3 seconds thereafter), as
required by sections 5.4.2 and 5.4.3 of appendix E. In some test
configurations, particularly during the lower flow rate water draws,
the inlet water and piping may retain heat from a previous draw,
causing the water entering the unit during the initial measurements to
be slightly outside of tolerance. Any supply water temperature reading
outside of the test tolerances would invalidate a test. However, due to
the small percentage of total water use that would be affected, supply
water temperatures that are slightly out of tolerance for the first one
or two data points would have a negligible effect on the overall test
result.\50\ This issue is less evident during the FHR test, which
specifies an initial temperature measurement 15 seconds after the start
of the water draw. This is not an issue during the Max GPM test due to
the system being in steady state during the entire test.
---------------------------------------------------------------------------
\50\ For example, the first two temperature readings would
reflect 8 seconds of water flow, in comparison to total water draw
durations ranging from 1 minute to over 8 minutes, according to the
water draw patterns defined in Tables III.1, III.2, III.3, and III.4
of appendix E.
---------------------------------------------------------------------------
In the April 2020 RFI, DOE requested feedback on whether one or two
supply water temperature data points outside of the test tolerance at
the beginning of a draw would have a measurable effect on the results
of the test. 85 FR 21104, 21111 (April 16, 2020). DOE further requested
feedback on whether it should consider relaxing the requirement for
supply water temperature tolerances at the start of a draw, and if so,
which methods are most appropriate for doing so while maintaining
accuracy and repeatability. Id. at 85 FR 21111-21112. DOE received
comments regarding these tolerances from stakeholders including AHRI,
A.O. Smith, NEEA, Rheem, BWC, CSA, Rinnai, and SMTI. These comments are
summarized and discussed in section III.C.3.a of the January 2022 NOPR.
87 FR 1554, 1576-1577 (Jan. 11, 2022).
In response to comments made on the April 2020 RFI, DOE proposed in
the January 2022 NOPR to increase the time between initiating the draw
and first measurement of supply water temperature from 5 seconds to 15
seconds in sections 5.4.2 and 5.4.3 of appendix E, as recommended by
the commenters. 87 FR 1554, 1577 (Jan. 11, 2022). DOE reasoned that the
proposed change may, if adopted, reduce test burden by reducing the
occurrence of a test being invalidated (which would require re-testing)
due to the first one or two water temperature readings exceeding the
defined temperature tolerance. Further, this proposed change would
eliminate the need to amend the supply water temperature tolerances
which, outside of the time period at the start of a draw, are
relatively easy to maintain. Id.
In response to the January 2022 NOPR, A.O. Smith reiterated its
previous comment that there would be no measurable effect on test
results by allowing one or two supply water temperature data points
outside of the current test tolerance at the beginning of a draw. The
commenter suggested that DOE should adopt the test set-up described in
ASHRAE 118.2-2022, which includes a purge line designed by third-party
laboratories to help achieve tolerances on supply water temperature.
A.O. Smith also commented that widening tolerances in certain cases may
ultimately cause variations in test results. (A.O. Smith, No. 37 at p.
5) In contrast, BWC supported DOE's proposal to increase the span
between the first draw initiation and the first temperature measurement
from 5 seconds to 15 seconds because it would reduce testing burden;
the 5-second
[[Page 40434]]
time interval requires significant and frequent purging which, if not
conducted, may invalidate tests. (BWC, No. 33 at p. 7) In response to
A.O. Smith, DOE reiterates its position, as previously stated in the
January 2022 NOPR, that although one or two measurements outside the
current tolerance may not have an effect on test results, DOE has
chosen to alleviate the issue of potential test invalidation by instead
increasing the time between initiating the draw and first measurement
of supply water temperature. Id.
After considering these comments, DOE has decided to adopt the
proposal from the January 2022 NOPR to increase the time between
initiating the draw and first measurement from 5 seconds to 15 seconds
in sections 5.4.2 and 5.4.3 of appendix E. In response to A.O. Smith's
suggestion that DOE adopt the test set-up in ASHRAE 118.2-2022, as
discussed in detail in section III.B.2.c of this document, DOE is
maintaining the current set-up directions for inlet water temperature
measurement in appendix E and not incorporating the updates found in
the ASHRAE 118.2-2022 figures because the addition of a bypass line and
thermal break was determined to be optional. However, increasing the
time of first recordation of the supply water temperature measurement
after the start of a draw from being taken at 5 seconds to being taken
at 15 seconds will allow units to reach a supply temperature within
tolerance without need for modifications to the test set-up.
2. Gas Pressure
For gas-fired water heaters, sections 2.7.2 and 2.7.3 of the
currently applicable appendix E require maintaining the gas supply
pressure in accordance with the manufacturer's specifications; or if
the supply pressure is not specified, maintaining a supply pressure of
7 to 10 inches of water column (1.7 to 2.5 kPa) for natural gas and 11
to 13 inches of water column (2.7 to 3.2 kPa) for propane gas. In
addition, for gas-fired water heaters with a pressure regulator,
sections 2.7.2 and 2.7.3 of the currently applicable appendix E require
the regulator outlet pressure to be within 10 percent of
the manufacturer's specified manifold pressure.
In the January 2022 NOPR, DOE noted that from a review of product
literature, DOE found that many gas-fired water heaters with modulating
input rate burners have a factory preset manifold pressure that is
computer-controlled and cannot be adjusted directly. Further, the
manufacturer-specified manifold pressure typically refers to when the
water heater is operating at the maximum firing rate. As a result, and
after considering comments on the April 2020 RFI, DOE proposed to
remove the 10 percent manifold pressure tolerance for
certain gas-fired water heaters, recognizing that some of these
products do not provide the capability to adjust the manifold pressure.
87 FR 1554, 1578-1579 (Jan. 11, 2022). DOE also proposed the addition
of an absolute manifold pressure tolerance of 0.2 inches
water column, which would be used for gas-fired water heaters with a
zero-governor valve for which the 10 percent tolerance
would be overly restrictive. Id. For example, applying the 10 percent to a manufacturer recommended gas pressure of 0.1
inches water column would result in a tolerance of 0.01
inches of water column, which is less than both the accuracy and
precision tolerances required for gas pressure instrumentation within
section 3.1 of the currently applicable appendix E. Further, DOE
proposed that the required gas pressures within appendix E apply when
operating at the manufacturer's specified input rate or, for modulating
input rate water heaters, the maximum input rate. Id.
DOE did not receive comments in response to the previously
discussed amendments to sections 2.7.2 and 2.7.3 of appendix E proposed
in the January 2022 NOPR concerning manifold pressure tolerance for
gas-fired water heaters. Accordingly, DOE is adopting these amendments
in this final rule for the reasons previously stated.
3. Input Rate
In addition to the gas pressure requirements, section 5.2.3 of the
currently applicable appendix E test procedure requires maintaining an
hourly Btu rating (i.e., input rate) that is within 2
percent of the value specified by the manufacturer (i.e., the nameplate
value). DOE has observed during testing that an input rate cannot be
achieved that is within 2 percent of the nameplate value
while maintaining the gas supply pressure and manifold pressure within
the required ranges for some gas-fired water heaters. In such
instances, it is common practice for the testing laboratory to modify
the size of the orifice that is shipped with the water heater; for
example, the testing laboratory may enlarge the orifice to allow enough
gas flow to achieve the nameplate input rating within the specified
tolerance, if the input rate is too low with the orifice as supplied.
For commercial water heating equipment, DOE addressed this issue by
specifying in the product-specific enforcement provisions that, if the
fuel input rate is still not within 2 percent of the rated
input after adjusting the manifold and supply pressures to their
specified limits, DOE will attempt to modify the gas inlet orifice. 10
CFR 429.134(n)(ii).
In the April 2020 RFI, DOE requested comment on whether provisions
should be added to the test procedure at appendix E to address water
heaters that cannot operate within 2 percent of the
nameplate rated input as shipped from the factory and how this issue
should be addressed. 85 FR 21104, 21112 (April 16, 2020). On this
topic, DOE received comments from manufacturers and their
representatives, including AHRI, Rheem, Rinnai, BWC, and CEC,
suggesting various methods to achieve the 2 percent
tolerance. These comments are summarized and discussed in the January
2022 NOPR. 87 FR 1554, 1579 (Jan. 11, 2022).
After considering these comments, DOE proposed in the January 2022
NOPR to add provisions to appendix E to provide further direction for
achieving an input rate that is 2 percent of the nameplate
value specified by the manufacturer. 87 FR 1554, 1579 (Jan. 11, 2022).
Specifically, DOE proposed to modify section 5.2.3 of appendix E to
require that the following steps be taken to achieve an input rate that
is 2 percent of the nameplate value specified by the
manufacturer:
(1) Attempt to increase or decrease the gas outlet pressure within
10 percent of the value specified on the nameplate to
achieve the nameplate input (within 2 percent).
(2) If the fuel input rate is still not within 2
percent of the nameplate input, increase or decrease the gas supply
pressure within the range specified on the nameplate.
(3) If the measured fuel input rate is still not within 2 percent of the certified rated input, modify the gas inlet
orifice as required to achieve a fuel input rate that is 2
percent of the nameplate input rate.
Id.
Regarding commenters' suggestion to check for leaks as an
additional step in the process, DOE noted that gas leak detection
should be part of a test laboratory's normal operating procedures, and,
therefore, detection does not require specification within DOE's test
procedures. 87 FR 1554, 1579 (Jan. 11, 2022). DOE also explained that
the purpose of adjusting the orifice during testing is to ensure that
the performance of the water heater is representative of performance at
the Btu rating specified by the manufacturer on the product's
nameplate, which informs
[[Page 40435]]
the field installation conditions. Allowing for adjustment of the
orifice reduces test burden and improves repeatability by providing
test laboratories with a last resort to maintain the hourly Btu rating
as specified by the manufacturer. Further, DOE noted that the proposal
that the orifice be modified would occur only after other options have
been exhausted. Lastly, DOE proposed that should a unit fail to achieve
an input within the 2 percent tolerance, DOE would continue testing
with the measured input value as opposed to the rated value (i.e., the
fuel input rate found via testing would be used for the purpose of
determining compliance). 87 FR 1554, 1579-1580 (Jan. 11, 2022).
In response to DOE's proposals on this topic in the January 2022
NOPR, AHRI agreed with the Department's proposal to first adjust the
manifold pressure and then modify the orifice if an input rate within 2
percent of the nameplate input rating is not achieved. (AHRI, No. 40 at
pp. 1-2)
Rheem, AHRI, and BWC commented that if the unit cannot reach input
rates within 2 percent of the nameplate rate, the unit is
likely faulty, and the test results should not be accepted. (Rheem, No.
31 at pp. 2-3; AHRI, No. 40 at pp. 1-2; BWC, No. 33 at p. 8) AHRI
suggested that if this occurs, the manufacturer should be contacted.
AHRI also stated that laboratory testing should only be performed by
qualified laboratory personnel, adding that the architecture of oil-
fired water heaters also introduces additional complexity for these
products. (AHRI, No. 40 at p. 2) BWC also commented that last-resort
orifice adjustments should only be performed by qualified laboratory
personnel, and indicated that DOE may wish to reference language in
Section A1.3.2.1.10 of the AHRI Residential Water Heater Operations
Manual.\51\ (BWC, No. 33 at p. 7)
---------------------------------------------------------------------------
\51\ AHRI maintains an Operations Manual for Residential Water
Heater Certification Program (AHRI Residential Water Heaters
Operations Manual), which addresses how testing will be done in the
AHRI certification program. Section A1.3.2.1.10 of the January 2022
edition of the AHRI Operations Manual for its Residential Water
Heaters states: ``If adjusting the manifold pressure does not
achieve the rated input, the operator shall re-orifice the unit
using an alternate orifice supplied by the manufacturer. [Note:
Manufacturers are to supply test facility with a selection of
orifices for use at the test facility. When a test unit is re-
orificed, the test facility will notify the manufacturer of the
alternate orifice used, and the manufacturer shall re-supply the
test facility with a replacement orifice.'' See: www.ahrinet.org/Portals/OM/RWH_OM.pdf. (Last accessed July 21, 2022.)
---------------------------------------------------------------------------
In response to these comments, DOE agrees with commenters that
testing should generally be performed at accredited laboratory
institutions by qualified personnel. In response to BWC's suggestion
that DOE reference section A1.3.2.1.10 of the AHRI Residential Water
Heater Operations Manual, DOE notes that the amendments to section
5.2.3 of appendix E are consistent with the instructions in the AHRI
Residential Water Heater Operations Manual in that they both require a
modification to the orifice, with the AHRI Operations Manual requiring
the testing laboratory to ``re-orifice'' the unit and the language DOE
is adopting requiring the test agency to ``modify'' the orifice. The
finalized amendment would provide a more flexible approach than the
language of section A1.3.2.1.10 of the AHRI Residential Water Heater
Operations Manual by not requiring involvement by the water heater
manufacturer in any modifications to the orifice. DOE notes that a unit
not achieving the nameplate input rate within 2 percent
could represent a malfunctioning unit or a broader issue in the design
of the model. Under the proposed test approach, such models would be
tested and evaluated for compliance based on its actual performance.
With regards to oil-fired water heaters, the amended section 5.2.3
provisions to appendix E reference the fuel oil supply requirements in
section 2.7.4 of appendix E, which provide adequate direction for the
adjustment.
After evaluating these comments, DOE is adopting modifications to
appendix E and 10 CFR 429.134 concerning input rate provisions as
proposed in the January 2022 NOPR and for the reasons previously
stated.
4. Ambient Test Condition Tolerances
Section 2.2 of appendix E specifies maintaining the ambient air
temperature between 65.0 [deg]F and 70.0 [deg]F (18.3 [deg]C and 21.1
[deg]C) on a continuous basis for all types of consumer water heaters
(and residential-duty commercial water heaters) other than heat pump
water heaters. For heat pump water heaters, the dry-bulb (ambient air)
temperature must be maintained between 67.5 [deg]F 1 [deg]F
(19.7 [deg]C 0.6 [deg]C), and the relative humidity must be
maintained at 50 percent 2 percent throughout the test.
Appendix E does not specify a relative humidity tolerance for non-heat
pump water heaters. Similar to the supply water temperature discussed
previously, a brief measurement of air temperature or relative humidity
that is only minimally outside of the test tolerance would invalidate a
test, but likely would have a negligible effect on the results of the
test, as the total time out of tolerance would be insignificant
compared to the total time of the test. In the April 2020 RFI, DOE
requested feedback on whether the tolerances for ambient air
temperature and relative humidity are difficult to maintain at the
start of a draw, and if so, whether DOE should consider relaxing these
requirements at the start of a draw and to what extent. 85 FR 21104,
21112 (April 16, 2020).
After considering comments received on the April 2020 RFI, DOE
proposed in the January 2022 NOPR to change the ambient temperature
requirement for non-heat pump water heaters to an average of 67.5
[deg]F 2.5 [deg]F, with a maximum deviation of 67.5 [deg]F
5 [deg]F, as opposed to only a maximum deviation of 67.5
[deg]F 2.5 [deg]F as currently specified in the test
procedure. 87 FR 1554, 1578 (Jan. 11, 2022). DOE reasoned that such a
change could, if adopted, reduce the need to re-run tests in instances
in which the results of the invalid test and the valid test would not
differ significantly, and, therefore, reduce test burden. Id. DOE also
noted that through a review of its available test data, DOE found that
short fluctuations in ambient temperature have little to no effect on
the test results of non-heat pump water heaters. Id.
For heat pump water heaters, DOE proposed in the January 2022 NOPR
to change the dry-bulb temperature requirement for heat pump water
heaters to an average of 67.5 [deg]F 1 [deg]F during
recoveries and an average of 67.5 [deg]F 2.5 [deg]F when
not recovering, with a maximum deviation of 67.5 [deg]F 5
[deg]F, as opposed to only a maximum deviation of 67.5 [deg]F 1 [deg]F as currently specified in the test procedure. Id. DOE
reasoned that this proposed change would maintain the stringency of the
dry-bulb temperature requirement while allowing for short deviations
from the targeted dry-bulb temperature range, which would reduce the
need to re-run tests in instances in which the results of the invalid
test and the valid test would not differ significantly, and, therefore,
reduce test burden. Id.
For heat pump water heaters, DOE also proposed in the January 2022
NOPR to increase the absolute relative humidity tolerance from 2 percent to 5 percent across the entire test, with
the average relative humidity between 50 percent 2 percent
during recoveries. 87 FR 1554, 1578 (Jan. 11, 2022). DOE reasoned that
this change, if adopted, would reduce test burden by reducing the need
to re-run tests in instances in which the results of the invalid test
and the valid test would not differ significantly. Id.
As noted, the currently applicable appendix E does not specify a
relative
[[Page 40436]]
humidity tolerance for non-heat pump water heaters. In the January 2022
NOPR, DOE explained that (as initially described in the April 2020
RFI), DOE conducted exploratory testing to investigate the effect of
relative humidity on the measured UEF values of two consumer gas-fired
instantaneous water heaters that are flow-activated and have less than
2 gallons of storage volume, one using non-condensing technology and
the other using condensing technology. 87 FR 1554, 1578 (Jan. 11,
2022). For each model, testing was performed at a relative humidity of
50 percent and at a relative humidity of 80 percent, and DOE found that
increasing relative humidity from 50 percent to 80 percent resulted in
a maximum change in UEF for the non-condensing and condensing models of
0.011 and 0.015, respectively. DOE noted that UEF is reported to the
nearest 0.01 (see 10 CFR 429.17(b)(2)), and, thus, a change in UEF on
the order of 0.01 to 0.02 as suggested by DOE's test results could be
considered as substantively impacting the test results. However, DOE
did not propose to adopt a tolerance on relative humidity in the
January 2022 NOPR, noting that it was still examining this issue. DOE
requested further comment and test data on whether a relative humidity
requirement should be added to appendix E for non-heat pump water
heaters. Id.
In response to the proposals made in the January 2022 NOPR
concerning ambient air temperature and relative humidity tolerances,
AHRI indicated its support of DOE's proposals to reduce test burden;
specifically, AHRI supported increasing test tolerances for ambient
temperature and relative humidity. (AHRI, Jan. 27, 2022 Public Meeting
Transcript, No. 27 at p. 40) NEEA and CA IOUs suggested that DOE should
specify a relative humidity level of 50 percent 5 percent
for all water heater types as was proposed for heat pump water heaters
in the January 2022 NOPR, which the commenters argued would reduce test
burden and ensure that results are comparable, repeatable, and
representative across all products and technologies. (NEEA, No. 30 at
pp. 1-2; CA IOUs, No. 36 at pp. 3-4)
BWC, however, anticipated difficulty maintaining even the proposed
5 percent tolerance during compressor cycling for electric
heat pump water heaters. BWC also argued that establishing a relative
humidity tolerance when testing water heaters other than heat pump
water heaters is unnecessary after observing low impact on UEF rating
during its testing of a gas instantaneous water heater at both 20
percent relative humidity and 100 percent relative humidity. (BWC, No.
33 at p. 7) In response to BWC's comments, DOE notes that BWC has not
provided, nor is DOE aware of, any data suggesting that a 5
percent relative humidity tolerance would be difficult to maintain for
heat pump water heaters.
After considering comments on the January 2022 NOPR, DOE is
adopting the changes to ambient air temperature and relative humidity
tolerances as proposed. Regarding the recommendation that DOE specify a
relative humidity level of 50 percent 5 percent for all
water heater types, DOE finds that it does not have adequate test data
to make such a change at this time, but DOE will continue to further
investigate this issue.
5. Electrical Supply Voltage Tolerances
For all water heaters, section 2.7.1 of the currently applicable
appendix E specifies maintaining the electrical supply voltage within
1 percent of the center of the voltage range specified by
the manufacturer. In the April 2020 RFI, DOE requested feedback on
whether the tolerances for electrical supply voltage are difficult to
maintain at the start of a draw, and if so, whether DOE should consider
relaxing these requirements at the start of a draw and to what extent.
85 FR 21104, 21112 (April 16, 2020).
In the January 2022 NOPR, after considering comments received in
response to the April 2020 RFI, DOE proposed to increase the electrical
supply voltage tolerance from 1 percent on a continuous
basis to 2 percent on a continuous basis. 87 FR 1554, 1577
(Jan. 11, 2022). DOE also proposed to add clarification that this
tolerance is only applicable beginning 5 seconds after the start of a
recovery to 5 seconds before the end of a recovery (i.e., only when the
water heater is undergoing a recovery). Id. DOE reasoned that these
proposed changes could reduce test burden by reducing the need to re-
run tests while maintaining the representativeness of the test
procedure. Id.
In response to these proposed changes, DOE received comment from
BWC supporting the proposal to increase the tolerance for electric
supply voltage. (BWC, No. 33 at p. 7)
DOE has thus determined that the proposed changes to sections 2.7.1
and 3.7 of appendix E concerning electric supply voltage tolerance are
appropriate and is adopting them in this final rule for the reasons
previously stated.
6. Flow Rate Tolerances
Section 5.4.2 of appendix E, Test Sequence for Water Heaters with
Rated Storage Volumes Greater Than or Equal to 2 Gallons, provides that
all draws during the 24-hour simulated-use test must be made at the
flow rates specified in the applicable draw pattern table in section
5.5 of this appendix, within a tolerance of 0.25 gallons
per minute (0.9 liters per minute). Section 5.4.3 of
appendix E, Test Sequence for Water Heaters with Rated Storage Volume
Less Than 2 Gallons, currently does not provide explicit instruction
for the tolerance on the flow rate.
Within the proposed amendments to the regulatory text provided in
the January 2022 NOPR, DOE included a proposed amendment to section
5.4.3 of appendix E to specify that flow rates for water heaters with
rated storage volume less than 2 gallons must be maintained within a
tolerance of 0.25 gallons per minute (0.9
liters per minute). 87 FR 1554, 1603 (Jan. 11, 2022). Because this
proposed change was not addressed explicitly in the preamble to the
January 2022 NOPR, DOE raised this issue again in the July 2022 SNOPR.
87 FR 42270, 42274 (July 14, 2022).
However, as discussed in the July 2022 SNOPR, there are models with
Max GPM delivery capacities at or below 1.0 gallon per minute, and for
these products, the flow rate used during draws must be the Max GPM
flow rate. A flow rate tolerance of 0.25 gallons per minute
would be too wide for products with Max GPM flow rates as low as 0.20
gallons per minute. Because the flow rate tolerance represents 25
percent of the flow rate at 1.0 gallon per minute, DOE proposed another
amendment to section 5.4.3 of appendix E in the July 2022 SNOR to
specify that for water heaters with a rated Max GPM of less than 1
gallon per minute, the flow rate tolerance shall be 25
percent of the rated Max GPM. DOE reasoned that for such products, a
flow rate tolerance 25 percent of the rated Max GPM would
represent the same level of variation (on a percentage basis) as for
products rated at 1.0 gallon per minute and subject to a tolerance of
0.25 gallon per minute. DOE noted that third-party
laboratories are currently technically capable of implementing this
methodology based on DOE's own test data. 87 FR 42270, 42274 (July 14,
2022).
In response to the July 2022 SNOPR, ASAP, ACEEE, and NRDC expressed
support for DOE's proposal to specify the flow rate tolerance
requirements for water heaters with a rated storage volume under 2
gallons. (ASAP, ACEEE, and NRDC, No. 54 at p. 1) BWC expressed they had
not had adequate time to conduct testing in order to determine the
impact of DOE's proposed
[[Page 40437]]
establishment of a 25 percent of maximum GPM threshold, and
as a result, the company had no further comments on that proposal.
(BWC, No. 48 at p. 2)
AHRI, A.O. Smith, and Rheem offered a few potential revisions to
the proposal. AHRI requested that DOE set a minimum tolerance of 0.1 gpm for the 24-hour simulated-use test for models with
maximum flow rates less than 1 gpm because the proposed 25
percent tolerance may be difficult to meet for some models. (AHRI, No.
55 at p. 2) A.O. Smith stated that the proposed flow rate tolerances
for the 24-hour simulated-use test for water heaters with a rated
storage volume less than 2 gallons would require manufacturers to
invest in more precise equipment and may also easily invalidate results
for units with low Max GPM values. Accordingly, A.O. Smith requested
that DOE adopt the proposed flow rate tolerance from the NOPR, rather
than the SNOPR. (A.O. Smith, No. 51 at pp. 2-3) Rheem indicated that
the proposed flow rate tolerance of 25 percent of Max GPM may be too
low for water heaters with very low max GPM and recommended that DOE
change the tolerance to the maximum between that value and 0.1 gpm. Rheem also recommended that all flow rate tolerances be
calculated based on the average of the flow rate over the entire draw,
so as to help reduce the number of invalid tests. (Rheem, No. 47 at p.
2)
As discussed previously, the lowest Max GPM certified to DOE is
currently 0.2 gpm, and DOE's amended test procedure must provide a
reproducible and repeatable method for testing products with such low
flow rates. DOE has determined that a tolerance of 0.1 gpm
could offer too much variability in test results for products rated
with such low flow rates. Specifically, a tolerance this wide would
represent 50 percent of the flow rate of this kind of water
heater, and because the temperature rise through the water heater is
inversely related to the flow rate when the water heater is constantly
firing at its maximum input rate, this variation in flow rate can cause
the temperature rise to potentially double. As stated, DOE is aware
that third-party laboratories are equipped with instrumentation to
measure flow rates within the tolerance level proposed in the July 2022
SNOPR.
DOE did not receive any test data in response to the July 2022
SNOPR indicating that manufacturers or third party test laboratories
would not be able to meet the tolerances proposed in the July 2022
SNOPR. Furthermore, DOE has concluded that a 0.1 gpm tolerance is too
large for the lowest flow rate models currently on the market (0.2 gpm)
and would be even more problematic if models with flow rates below 0.2
gpm are introduced in the future. As such, in this final rule, DOE is
adopting the flow rate tolerance amendments to sections 5.4.2 and 5.4.3
of appendix E, as proposed in the July 2022 SNOPR.
7. Optional Test Conditions for Heat Pump Water Heaters
In the course of this rulemaking, DOE has received numerous
comments from stakeholders requesting that DOE consider allowing
manufacturers to optionally rate heat pump water heaters to test
conditions other than those currently specified in appendix E, which
are intended to be representative of national average water and air
temperatures. Commenters noted that heat pump operation is dependent
upon the surrounding ambient air temperatures,\52\ and that there would
be significant value to providing consumers, installers, and utilities
with efficiency representations that are closer to the conditions for
particular climates. See 87 FR 1554, 1580 (Jan. 11, 2022) and 87 FR
42270, 42275-42276 (July 14, 2022).
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\52\ Because heat pumps ``transfer thermal energy from one
temperature level to a higher temperature level'' (see 42 U.S.C.
6291(27)(C) and 10 CFR 430.2), the energy efficiency is dependent
upon the difference between temperatures that must be overcome by
the heat pump cycle. As discussed in section III.A.2 of this
document, heat pump water heaters are typically air-source, i.e.,
these products source heat from surrounding air and transfer it to
domestic hot water. Therefore, lower ambient air temperatures, such
as those experienced in colder climates or due to seasonal
differences, would result in lower efficiencies.
---------------------------------------------------------------------------
For example, Lutz commented that a single inlet water temperature
may not be representative for all cases because this may vary by
geographical location, and, furthermore, that taking this into account
is even more important for split-system heat pump water heaters with an
outdoor unit. (Lutz, No. 35 at p. 1) NEEA argued that, because heat
pump water heater performance can be affected by variations in ambient
conditions, DOE should clarify what manufacturers can report about a
unit's performance at conditions other than those required by the test
procedure. NEEA added that information regarding delivery capacity and
sizing guidance would be important for installers. (NEEA, No. 30 at p.
3)
In the January 2022 NOPR, DOE did not propose to allow for optional
(voluntary) representations of heat pump water heater efficiencies at
non-standard temperatures because there was not enough information at
the time to identify the most representative alternate test conditions
(e.g., regional conditions). 87 FR 1554, 1580 (Jan. 11, 2022). However,
commenters on the July 2022 SNOPR identified the NEEA Advanced Water
Heating Specification (currently at version 8.0, AWHS v8.0) provides
multiple conditions which manufacturers are providing ratings at. 87 FR
42270, 42775-42276 (July 14, 2022). Consequentially, DOE revisited the
NEEA Advanced Water Heating Specification to determine how the test
conditions specified in that document might be applied for optional
representations in the DOE test procedure.
Section 2.2 of appendix E currently specifies that the ambient air
temperature shall be maintained between 65.0 [deg]F and 70.0 [deg]F
(18.3 [deg]C and 21.1 [deg]C) on a continuous basis during the test.
Additionally, for heat pump water heaters, that test procedure
provision provides that the dry-bulb temperature shall be maintained at
67.5 [deg]F 1 [deg]F (19.7 [deg]C 0.6 [deg]C)
and that the relative humidity shall be maintained at 50 percent 2 percent throughout the test. EPCA requires that the DOE test
procedure must be reasonably designed to produce test results which
measure energy efficiency during a representative average use cycle or
period of use. (42 U.S.C. 6293(b)(3)) While the test conditions in the
current appendix E test procedure must remain representative for the
nation as a whole, in the July 2022 SNOPR, DOE tentatively determined
that comments from interested parties have demonstrated that allowing
additional representations of efficiency at alternative ambient
conditions could provide consumers with additional information about
the expected performance of heat pump water heaters at conditions that
are representative of their specific installation circumstances. For
other types of covered products and equipment, DOE has adopted optional
metrics for voluntary representations where it was determined that the
primary efficiency metric would not be representative for certain
installation conditions common for the product or equipment.\53\ As
discussed in the July
[[Page 40438]]
2022 SNOPR, depending on the installation location (e.g., whether the
water heater is installed in an unconditioned space such as a garage or
attic), the ambient conditions may vary significantly from the
conditions in the DOE test method, thereby resulting in significantly
different performance for heat pump water heater products. Thus, DOE
reversed its position and tentatively determined to allow for certain
optional representations for additional ambient conditions. 87 FR
42270, 42275-42276 (July 14, 2022).
---------------------------------------------------------------------------
\53\ For example, on July 27, 2022, DOE published a final rule
in the Federal Register pertaining to test procedures for direct-
expansion dedicated outdoor air systems, including provisions for
optional representations of energy efficiency when the equipment is
installed in applications where inlet water conditions are expected
to deviate substantially from standard conditions. See 10 CFR part
431, subpart F, appendix B, section 2.2.3(d) as established by that
final rule. 87 FR 45164, 45201 (July 27, 2022).
---------------------------------------------------------------------------
AWHS v8.0 was published by NEEA on March 1, 2022. Though early
editions of the AWHS focused primarily on providing more representative
performance metrics for heat pump water heaters in cold climates, the
latest editions are now more broadly focused on providing
representative performance metrics for heat pump water heaters across
all climates. Performance metrics in the AWHS are generally calculated
by measuring energy efficiency at multiple (two or more) ambient test
conditions, linearly interpolating between the test results, and
finally calculating an ambient temperature-weighted efficiency metric
using temperature bin data. The metric is a cold climate efficiency
(CCE) rating for integrated heat pump water heaters installed in semi-
conditioned spaces (i.e., garage, basement) and a seasonal coefficient
of performance (SCOP) for split-system heat pump water heaters (where
the heat pump is separated from the storage tank and located outdoors).
DOE tentatively determined in the July 2022 SNOPR that adopting the
test conditions in AWHS v8.0 would not significantly increase test
burden for manufacturers who choose to provide these ratings, because
manufacturers are already providing representations of CCE and SCOP to
NEEA's Qualified Products List.\54\ The test conditions in AWHS v8.0
differ from the standard conditions in appendix E in terms of inlet
water temperature, ambient dry-bulb temperatures, and ambient relative
humidity. A detailed discussion of these conditions was provided in the
July 2022 SNOPR. 87 FR 42270, 42276 (July 14, 2022).
---------------------------------------------------------------------------
\54\ Available at: neea.org/img/documents/residential-unitary-HPWH-qualified-products-list.pdf (Last accessed on May 11, 2022).
---------------------------------------------------------------------------
In the July 2022 SNOPR, DOE proposed to allow voluntary
representations of a new metric, EX, analogous to UEF, at
optional test conditions for heat pump water heaters. The subscript
``X'' would be used to denote the set of conditions being used, and
these voluntary representations of EX would not be
integrated together to form a seasonal efficiency metric--in contrast
to the methodology in AWHS v8.0. DOE's proposal intended to eliminate
any reduction in representativeness caused by assumptions in climate
weighting factors. Without substantial additional data, DOE tentatively
determined that it would not be able to evaluate whether or not the
weighting factors in AWHS v8.0 (used to create a weighted average of
the results at various test conditions together into one metric, CCE or
SCOP) are representative of climates in the United States, and, thus,
DOE proposed to allow for the use of standalone EX
representations only in a way that it is clear to a consumer what test
conditions were used in determining the rating. 87 FR 42270, 42276-
42277 (July 14, 2022).
In response to the July 2022 SNOPR, ASAP, ACEEE, and NRDC expressed
support for DOE's proposal to adopt optional test conditions needed for
calculating climate-specific efficiencies. (ASAP, ACEEE, and NRDC, No.
54 at p. 2) A.O. Smith acknowledged that optional efficiency ratings
may have consumer utility and stated that additional measures of
efficiency may assist with increasing market adoption of heat pump
water heaters. (A.O. Smith, No. 51 at pp. 3-4) The CA IOUs supported
DOE's tentative determination to allow optional efficiency
representations at multiple test conditions for heat pump water
heaters, stating that this change will help consumers choose the heat
pump water heater that best suits their needs and will aid in the
maturation and expansion of the heat pump water heater market. (CA
IOUs, No. 52 at pp. 1-2)
NEEA also supported DOE's proposal to allow for optional efficiency
representations at alternative ambient conditions for heat pump water
heaters but encouraged DOE not to limit condition representations based
on the specific type of heat pump. NEEA stated that both split-system
water heaters and heat pump-only water heaters can be designed for any
combination of indoor, outdoor, and semi-conditioned space operation of
the heat pump component. Therefore, NEEA suggested that DOE should not
specify which metrics may be reported on the basis of heat pump type,
as these additional representations would not add any burden to
manufacturers because they are optional. (NEEA, No. 56 at pp. 1-2)
A.O. Smith requested that DOE clarify whether manufacturers may
represent optional metrics as consistent with appendix E. (A.O. Smith,
No. 51 at pp. 3-4)
In response to NEEA's comment, DOE acknowledges that split-system
and heat pump-only water heaters may be installed in a variety of
configurations which can vary the location of components. For example,
a heat pump module (comprised of the compressor, evaporator, and
expansion devices) could be installed either outdoors or in a separate
room indoors. Therefore, DOE has updated the table of optional test
conditions in section 2.8 of appendix E to reflect this fact by
allowing split-system and heat pump-only water heaters to be tested at
the conditions specified for any EX. In response to NEEA and
A.O. Smith, DOE notes that manufacturers will be able to represent
optional metrics as specified in the amended appendix E.
Rheem stated that the Code of Federal Regulations only allows
voluntary ratings for distribution transformers and commercial prerinse
spray valves. Rheem also stated that the 24-hour simulated-use test for
water heaters is more complex and very different from those specified
for these other types of equipment which, according to Rheem, have test
procedures that easily handle testing at alternate conditions. (Rheem,
No. 47 at pp. 2-3)
In response to Rheem's comment, DOE notes that optional additional
test conditions are being adopted in appendix E because industry has
already demonstrated its desire for them through testing at specific
conditions in compliance with NEEA Advanced Water Heating Specification
v8.0. By amending appendix E to include these conditions, DOE is simply
standardizing current industry practices. Because ratings at such
conditions are voluntary, DOE anticipates that there would be no undue
burden associated with adoption of such provisions in this final rule.
DOE also notes that water heaters are used in a variety of
conditions and are expected to operate at all times despite them. This
sets water heaters apart as compared to what is expected of other
products (e.g., air conditioners), which are only active and operate in
response to specific conditions. Test procedures for these products
already include a range of conditions, and, therefore, they do not
require optional representations of performance. For these other types
of products, the range of conditions experienced would be narrower and
more predictable than the range of conditions experienced by heat pump
water heaters,\55\ and, therefore, it is not
[[Page 40439]]
unduly burdensome to require testing at multiple conditions for these
other types of products. The narrower range of air conditions also
ensures that the results of testing are highly representative of the
product's average performance. This is not the case for heat pump water
heaters because of the many different installation configurations which
are applicable to heat pump water heaters--for instance, some are
located indoors, and some are located outdoors. Allowing testing at
these conditions to be optional avoids burdening manufacturers with
test conditions that may not apply to their products. Using a different
metric (EX) for these conditions also ensures that these
representations are not read as being valid for all consumer
applications; instead, the representation is specific to the condition
at which the water heater is being tested.
---------------------------------------------------------------------------
\55\ For example, Table 11 in section 3.6.1 of appendix M1 to
subpart B of 10 CFR part 430 provides the heating mode test
conditions for central (space-conditioning) heat pumps having a
single-speed compressor and a fixed-speed indoor blower. The range
of temperatures at which the outdoor evaporator coil can be tested
is from 5 [deg]F at the lowest to 47 [deg]F at the highest. Because
a heat pump water heater would also be active during the summer
months, DOE has determined that the representative range of outdoor
ambient temperatures for a split-system heat pump water heater's
outdoor evaporator coil could be from 5 [deg]F at the lowest to 95
[deg]F at the highest.
---------------------------------------------------------------------------
AHRI, BWC, and Rheem suggested that allowing optional ambient test
conditions may increase manufacturer burden, arguing that they may
eventually be driven by the market to conduct such testing. (AHRI, No.
55 at p. 3; BWC, No. 48 at p. 2; Rheem, No. 47 at p. 3) BWC also stated
that not all manufacturers are currently conducting testing per NEEA
Advanced Water Heating Specification v8.0, and that DOE allowing
optional testing based on its test conditions would cause significant
burden. (BWC, No. 48 at p. 2) Rheem requested that DOE either adopt the
position from the last test procedure rulemaking that requiring
additional testing at alternate conditions is unduly burdensome or
provide justification for why it is not. (Rheem, No. 47 at p. 3) AHRI
indicated that third-party laboratories may not be equipped to perform
the optional tests at additional ambient conditions because of how the
test set-up differs from that used in the standard test and that large
capital burdens would need to be incurred in order to comply. AHRI also
expressed concern that DOE did not adequately solicit manufacturer and
laboratory feedback on increased test burden due to the proposed
optional additional ambient test conditions. (AHRI, No. 55 at p. 4)
Rheem also stated that optional tests currently performed by
manufacturers are not necessarily done to be in accordance with AWHS
and that NEEA, an entity which is not a manufacturer, distributor,
retailer, or private labeler, was not restricted from making
representations of products based on testing which did not use the DOE
test procedure. (Rheem, No. 47 at pp. 2-3)
In response to these comments, DOE disagrees that optional testing
will increase manufacturer burden for a number of reasons. First, as
previously discussed in the July 2022 SNOPR, DOE is currently aware of
17 water heater brands represented in the Qualified Products List for
AWHS v8.0. Participation in NEEA's program using Advanced Water Heating
Specification v8.0 requires manufacturers to submit their own test
results at the prescribed test conditions; NEEA does not appear to
perform testing on behalf of manufacturers, per its own
documentation.\56\ Most importantly, DOE reiterates that this testing
is ultimately optional, so a manufacturer may decline to undertake any
additional testing. Consequently, DOE has concluded that allowing
optional additional testing conditions will not increase burden for
manufacturers.
---------------------------------------------------------------------------
\56\ Steps in the process flow for NEEA's AWHS Qualified
Products List can be found online at: neea.org/img/documents/qualified-products-process-flow.pdf (Last accessed on Sept. 10,
2022).
---------------------------------------------------------------------------
BWC claimed that DOE is not authorized under EPCA to allow
manufacturers to have additional optional representations of
performance and requested that DOE clarify its statutory authority.
(BWC, No. 48 at p. 2) Rheem claimed that justifications for other
products allowing optional additional ratings do not apply to consumer
water heaters and stated that EPCA \57\ can be interpreted as
prohibiting optional additional test conditions that are not in the
test procedure.
---------------------------------------------------------------------------
\57\ The commenter cited 42 U.S.C. 6293(c), ``Restriction on
Certain Representations,'' of which subsection (1) prohibits
representations not made in accordance with the currently applicable
test procedure and subsection (2) prohibits representations not made
in accordance with a new or amended test procedure 180 days after
the adoption of that test procedure.
---------------------------------------------------------------------------
In response to these comments, DOE finds BWC's and Rheem's
interpretations of 42 U.S.C. 6293(c) to be misguided. The statute
requires appliance efficiency testing and representations to be done in
accordance with the DOE test procedure. DOE routinely incorporates by
reference private sector testing methods into Federal test procedures,
and nothing in the statute would prohibit adoption of optional test
conditions as these commenters suggest. DOE notes that the optional
conditions at which manufacturers may choose to test their products are
specified as part of the AWHS v8.0 test procedure and are not left up
to manufacturers to determine individually. Precisely by including
these optional conditions and metrics in the appendix E test procedure,
DOE is permitting manufacturers and other parties to make such
representations to the public in the manner which the statute
contemplates. EPCA requires that a uniform efficiency metric (i.e.,
UEF) be used to rate all water heaters; however, the addition of
optional representations does not prevent manufacturers from making its
mandatory UEF rating under the required conditions. By virtue of the
new heat pump water heater testing and metric being optional, DOE would
not enforce the required energy conservation standard based upon
results of testing at optional test conditions. Permitting testing
under the specified optional conditions may also serve another purpose.
In a future rulemaking considering further amendments to the appendix E
test procedure, DOE may consider adopting multiple ambient test
conditions for certain types of water heaters, if data from testing at
these additional conditions proves that this methodology yields results
more representative of energy consumption over an average use cycle.
Hence, allowing manufacturers to test and rate these optional
conditions would allow more data to be collected for potential future
amendments.
AHRI requested that DOE provide any data justifying the proposal to
include optional ambient test conditions to stakeholders. (AHRI, No. 55
at pp. 2-3) BWC requested that DOE readopt its position that there is
insufficient data to support optional additional ambient test
conditions and to provide the data that caused DOE to make this
proposal in the SNOPR. (BWC, No. 48 at p. 2)
In response, DOE notes that NEEA's Qualified Products List \58\
indicates the climate-weighted average performance of heat pump water
heaters as tested by manufacturers to the various conditions in AWHS
v8.0. (This performance metric, ``cool climate efficiency,'' is a
result of testing under the optional conditions which DOE is adopting
in this final rule.) From the data points in NEEA's Qualified Products
List, manufacturers demonstrate that heat pump water heaters are less
energy-efficient at these additional conditions. For example, Tier 4
products, which
[[Page 40440]]
range in UEF from 3.45 to 4.02 at DOE's required test conditions, have
cool climate efficiencies ranging from 3.1 to 3.5. These ratings have
been provided to NEEA by manufacturers conducting their own testing.
While DOE is not adopting the cool climate efficiency metric (because
it requires testing at all of the additional ambient conditions, and
that would significantly increase burden for a manufacturer wanting to
provide consumers with additional ratings), these cool climate
efficiency ratings are an objective indication of how performance can
be impacted by varying climatic conditions. By adopting EX
optional ratings in appendix E, DOE expects to facilitate manufacturer
testing and the generation of relevant data related to water heater
performance at these additional conditions. Again, the standardized
voluntary ratings could be considered in a future rulemaking to
determine the representativeness of the current mandatory ambient
conditions in appendix E.
---------------------------------------------------------------------------
\58\ Available at: www.neea.org/img/documents/residential-unitary-HPWH-qualified-products-list.pdf (Last accessed on Sept. 18,
2022).
---------------------------------------------------------------------------
AHRI also stated that DOE has not provided evidence that NEEA's
AWHS test conditions ensure repeatability and reproducibility and
suggested that these requirements still apply even if the procedure is
optional. (AHRI, No. 55 at p. 4)
Repeatability refers to the quality of a test method which allows a
laboratory to achieve the same results when a product is tested on more
than one occasion. Reproducibility refers to the quality of a test
method which allows one laboratory to reproduce the results obtained by
another laboratory. Test tolerances and set-up requirements are
essential to these parameters. As proposed in the July 2022 SNOPR and
adopted in this final rule, the optional test conditions would be
tested per the same tolerances and set-up requirements as the current
UEF test procedure--simply at different temperatures. Utilization of
this Federal testing framework makes it possible for DOE to ensure that
the voluntary ratings of EX are repeatable and reproducible.
AHRI stated that DOE has not provided references to other occasions
when it has adopted optional metrics for voluntary representations for
other products or equipment. (AHRI, No. 55 at p. 4) AHRI requested that
DOE remove the proposal concerning optional additional ambient test
conditions from this rulemaking and instead address it in a subsequent
rulemaking for these products. (AHRI, No. 55 at p. 4)
In response and as discussed earlier in this section, DOE has
previously adopted optional metrics for voluntary representations where
there was a clear industry precedent for these metrics and a consumer
utility for having the additional performance information. Most
recently, this was done for dedicated outdoor air systems (DOASes). For
heat pump water heaters, there is a clear indication that industry
wishes to provide consumers with these additional ratings because
numerous product representations have been submitted by several
manufacturers to NEEA for its Qualified Products List. DOE's amendment
to officially adopt these supplemental test conditions into the
appendix E test procedure ensures that when these representations are
provided, they are done so based on a consistent test method.
Rheem stated that it has not had enough time to evaluate DOE's
proposal to allow optional additional test conditions. (Rheem, No. 47
at p. 2) Rheem requested that DOE clarify the sampling, certification,
and enforcement provisions for heat pump water heaters with alternate
representations. (Rheem, No. 47 at p. 3)
In response, DOE notes that it provided a three-week comment period
on the limited set of issues presented in the July 2022 SNOPR, and
other commenters were able to assess DOE's latest proposal and provide
substantive comments during the time allotted. By virtue of
EX being an optional metric for voluntary representations,
DOE will not require certification of EX representations.
Manufacturers who opt to determine Ex must apply the sampling
requirements for determining UEF in order to ensure consistency in
values provided to consumers.
Rheem recommended that DOE fully evaluate the alternate conditions
specified in AWHS before adopting them. (Rheem, No. 47 at p. 4) Rheem
stated that it has not had time to fully evaluate the alternate test
conditions and questions whether they adequately represent the entire
Nation, or only represent the Northwest, as these test conditions were
developed by NEEA. (Rheem, No. 47 at p. 4)
To clarify, by allowing manufacturers to make separate
EX representations for each set of test conditions, the
voluntary representations, individually, are not designed to be
representative of the entire United States. To do so would require
these test conditions to be averaged together based on prevalence of
climate conditions at a given location, and this aspect of NEEA's AWHS
v8.0 is not being used in the appendix E optional representations.
Instead, it is DOE's mandatory testing scenario--the determination of
UEF through the standard rating conditions--that is intended to reflect
average conditions for the Nation as a whole. DOE has evaluated the
full set of test conditions NEEA specifies in AWHS v8.0 and has
determined that these conditions are meant to cover the full range of
operating conditions (temperature and humidity) possible across the
United States. They are not meant to only represent the range of
conditions possible in the Northwestern United States. The purpose of
EX representations, as employed by DOE at appendix E, is to
indicate performance at individual rating points, which, along with
UEF, will provide additional information to consumers. Manufacturers
will be permitted to make voluntary representations at any of the
optional test conditions specified in appendix E.
BWC stated that DOE's proposal to allow optional additional test
conditions would confuse consumers and installers because they may not
have the means to sufficiently assess environmental conditions where
they live. (BWC, No. 48 at p. 3) In addition, BWC commented that
allowing optional additional test conditions may cause scarcity of
testing resources, thereby significantly increasing manufacturer
burden. (BWC, No. 48 at p. 3)
DOE disagrees with BWC's presumption that consumers and installers
cannot assess environmental conditions. These parties may easily access
a variety of sources of freely available weather data, such as
information generated by the National Oceanic and Atmospheric
Administration (NOAA) and the National Weather Service (NWS).\59\ \60\
In addition, installers of central air conditioning, central heat pump,
and cool-climate heat pump units already have sufficient access to
local environmental data required to install them. These data are the
same data required for the installation of water heaters. Although DOE
understands BWC's concern regarding limited testing resources, DOE once
again reiterates that this testing is ultimately optional;
manufacturers are not obligated to make capital investments or dedicate
testing resources if it is not feasible. To the extent that optional
testing would
[[Page 40441]]
utilize resources that would otherwise be used for mandatory testing,
DOE notes that manufacturers would have the option of foregoing or
delaying optional testing to accommodate mandatory testing since DOE is
not requiring use of any of the optional test conditions. Furthermore,
as manufacturers have already provided ratings to NEEA at these
alternate conditions, DOE does not believe that officially adopting
these test conditions would change overall available laboratory
capacity, especially as manufacturers may opt to test these optional
conditions in-house.
---------------------------------------------------------------------------
\59\ The National Weather Service (NWS) maintains a Climate page
on their website which provides past weather records and climate
information for regions of the United States and its territories.
This page is available at: www.weather.gov/wrh/climate. (Last
accessed Sept. 28, 2022)
\60\ The National Centers for Environmental Information (NCEI)
maintains a Past Weather page with past weather data from weather
stations around the world. This data is available for download in
various file formats. This page is available at: www.ncei.noaa.gov/access/past-weather/. (Last accessed Sept. 28, 2022)
---------------------------------------------------------------------------
ASAP, ACEEE, and NRDC requested that DOE clarify which optional
test conditions would apply to split-system water heaters with an
indoor heat pump component. (ASAP, ACEEE, and NRDC, No. 54 at p. 2) In
response, DOE notes that the included optional test conditions are
intended to be used at the discretion of the manufacturer.
Manufacturers are free to use the conditions specified by the test
points they believe are most similar to what their product may
experience during operation. For example, a manufacturer of a split-
system heat pump water heater whose compressor and storage tank are
located outdoors and indoors, respectively, may decide it would be
beneficial to evaluate the product's performance at an outdoor ambient
temperature of 34.0 [deg]F. In this case, the manufacturer would test
the product using the conditions specified by the E34
metric: outdoor dry-bulb temperature and relative humidity of 34.0
[deg]F and 72 percent, respectively, indoor dry-bulb temperature and
relative humidity of 67.5 [deg]F and 50 percent, respectively, and
supply water temperature of 47.0 [deg]F.
Rheem requested that DOE evaluate wider tolerance ranges for the
alternate test conditions. Rheem also asked that DOE clarify whether
relative humidity control is required for storage tanks during split-
system water heater tests, in which case, the commenter argued that two
psychrometric chambers would be required. (Rheem, No. 47 at pp. 3-4)
In response, DOE notes that the amendments being adopted for
ambient condition tolerances during UEF testing would also apply to
EX testing, hence allowing a similarly wider tolerance range
to apply at all conditions. When testing a split-system heat pump water
heater or heat pump water heater requiring a separate storage tank, the
heat pump portion of the system shall be tested at the relative
humidity conditions specified, and the storage tank can be tested at
either the same conditions or the conditions specified in section 2.2.1
of appendix E. Thus, the relative humidity control is not required for
the storage tank during split-system water heater tests. This is
discussed further in section III.D.1 of this document.
Rheem requested that DOE remove ``heat pump only'' from the table
of alternate test conditions because they are the same as the outdoor
portion of a split-system water heater. (Rheem, No. 47 at p. 4)
In response, DOE wishes to make clear that circulating heat pump
water heaters (heat pump-only water heaters) and split-system water
heaters are not identical. Circulating heat pump water heaters are
instantaneous-type units, whereas split-system heat pump water heaters
have a storage tank and are, overall, storage-type units. Both types of
products may have the heat pump module located remotely from the
storage tank, but still indoors. In light of this comment, DOE has
modified the table of alternate test conditions to explicitly allow
split-system and circulating heat pump water heaters to be tested at
any of the conditions specified.
D. Test Set-Up and Installation
1. Split-System Heat Pump Water Heaters
In section III.A.2 of this document, DOE discussed a new definition
for this subset of heat pump water heaters. As established by this
final rule, a ``split-system heat pump water heater'' means a heat
pump-type water heater with an indoor storage tank and outdoor heat
pump component. In considering such products, DOE had found that in a
split-system heat pump, the heat pump part of the system is typically
installed outdoors and, as a result, does not use the indoor ambient
air for water heating directly. In the current appendix E test
procedure, different ambient conditions are specified in appendix E for
heat pump water heaters and non-heat pump water heaters, but there are
no specific conditions for split-system heat pump water heaters.
In the January 2022 NOPR, DOE proposed to specify that the heat
pump part of the system shall be tested using the heat pump water
heater dry-bulb temperature and relative humidity requirements, while
the storage tank part of the system shall be tested using the non-heat
pump water heater ambient temperature and relative humidity
requirements. DOE noted that the required non-heat pump water heater
ambient conditions can be met by keeping the entire system within the
dry-bulb temperature and relative humidity requirements for heat pump
water heaters (i.e., both parts of the system can be tested in the same
psychrometric chamber). 87 FR 1554, 1583 (Jan. 11, 2022).
On this topic, AHRI requested that DOE clarify whether the proposed
testing requirements for split-system heat pump water heaters would
mean testing would have to be carried out with the heat pump and
storage tank in separate rooms. (AHRI, Jan, 27, 2022 Public Meeting
Transcript, No. 27 at p. 42) NYSERDA indicated that DOE should
collaborate with manufacturers to ensure that test conditions and set-
up for split-system heat pump water heaters are consistent, repeatable,
and not burdensome. (NYSERDA, No. 32 at p. 4) BWC suggested that DOE
should permit manufacturers and testing laboratories as much
flexibility as possible when determining the testing locations of
separate system components and not prevent test set-ups that can meet
the specified conditions for both systems in the same room or area, if
a manufacturer or test laboratory so chooses. (BWC, No. 33 at p. 9)
Rheem requested clarification that the storage tank can be tested at
the heat pump test conditions and still meet the requirements of
appendix E. (Rheem, No. 31 at p. 3)
To reiterate DOE's explanation in the January 2022 NOPR, if a
single room, chamber, or area is capable of meeting the dry-bulb
temperature and relative humidity requirements for heat pump water
heaters, then, like integrated heat pump water heaters, split-system
heat pump water heaters can be tested with both indoor and outdoor
components in the same space. In response to NYSERDA, by adopting this
approach, DOE is aligning with the methodology used already by industry
when testing heat pump water heater products for other representations
(such as the Qualified Products List for NEEA's AWHS v8.0), so
consequently, DOE expects the results generated to be consistent,
repeatable, and not unduly burdensome.
2. Mixing Valves
As discussed in section III.E.1 of this final rule, there are
certain water heater designs which raise the temperature of water
stored in the tank significantly above the outlet water temperature,
and these products are meant to be used with a mixing valve (which may
or may not be provided with or built-in to the unit) so that the hot
stored water can be tempered down to a more typical delivery
temperature. The January 2022 NOPR noted that the installation
instructions in section 4 of appendix E do not address cases when a
separate
[[Page 40442]]
mixing valve should be installed. 87 FR 1554, 1580 (Jan. 11, 2022).
The January 2022 NOPR proposed to incorporate instructions for
separate mixing valve installations based on those found in the ENERGY
STAR Test Method to Validate Demand Response for Connected Residential
Water Heaters (ENERGY STAR Connected Test Method) (published on April
5, 2021). This set-up requires installing the mixing valve in
accordance with the water heater and mixing valve manufacturer's
instructions. Absent instruction from the water heater or mixing valve
manufacturer, the mixing valve is to be installed in the outlet water
line, upstream of the outlet water temperature measurement location,
with the cold water supplied from a tee installed in the inlet water
line, downstream of the inlet water temperature measurement location
(i.e., the mixing valve and cold water tee are installed within the
inlet and outlet water temperature measurement locations). Section 4.1
of the ENERGY STAR Connected Test Method further clarifies that if the
liquid flow rate and/or mass measuring instrumentation is installed on
the outlet side of the water heater, that it shall be installed after
the mixing valve. 87 FR 1554, 1580 (Jan. 11, 2022).
On July 18, 2022, EPA published the ENERGY STAR Connected
Residential Water Heaters Test Method to Validate Demand Response,
Version 1.2.\61\ The updated test method retains the same instructions
for setting up mixing valves in section 4.1.
---------------------------------------------------------------------------
\61\ Available at: www.energystar.gov/products/spec/residential_water_heaters_specification_version_5_0_pd (Last
accessed on July 25, 2022).
---------------------------------------------------------------------------
In response to the January 2022 NOPR, ASAP, ACEEE, and NCLC; AET;
A.O. Smith; and the CA IOUs supported DOE's proposal to include
instructions for the installation of a mixing valve. (ASAP, ACEEE, and
NCLC, No. 34 at pp. 1-2; AET, No. 29 at p. 2; A.O. Smith, No. 37 at p.
4; CA IOUs, No. 36 at p. 4) A.O. Smith also commented that, depending
on the design, there may be additional steps that are required (e.g.,
independently adjusting the tank thermostat and the mixing valve
settings to remain in default mode per the manufacturer's
instructions), and, therefore, DOE should clarify the details of this
procedure. (A.O. Smith, No. 37 at p. 4)
In this final rule, DOE is adopting the proposed installation
instructions for mixing valves as discussed in the January 2022 NOPR.
To the extent that there may be additional steps required to maintain
normal operation with the mixing valve installed per the manufacturer's
specifications, these instructions would be heeded in accordance with
section 4.3 of the amended appendix E test procedure. As described in
section III.E.1 of this document, DOE is also providing an optional
test method for high storage tank temperature operation, and this test
method involves the installation of mixing valves for products which do
not come so equipped.
3. Flow Meter Location
The current test procedure does not specify where in the flow path
the flow volume and density of water must be measured, and this allows
for laboratory test set-ups to perform these measurements either on the
cold/inlet side of the water heater or on the hot/outlet side. As
discussed in this rulemaking, water mass calculations can account for
the difference in the density of water at the inlet vs. the outlet
(colder water at the inlet has a higher density); however, there could
be cases when a measurement based on the inlet location could result in
inaccurate mass calculations. Specifically, some of the mass of inlet
water could, after being heated, expand out of the water heater into
the expansion tank and be purged prior to a draw. Any ``expanded''
volume of water that is lost through the bypass (purge) line could be
included in a volume measurement taken at the inlet, but not be
included in a volume measurement taken at the outlet. 87 FR 1554, 1581
(Jan. 11, 2022). The Department requested information and data
regarding the issue of flow meter location (inlet vs. outlet) in the
April 2020 RFI and the January 2022 NOPR. 85 FR 21104, 21113 (April 16,
2020); 87 FR 1554, 1581 (Jan. 11, 2022).
In response to the April 2020 RFI, four commenters either disagreed
with requiring the flow meter to be located at the outlet or requested
that DOE continue to allow facilities to choose the location, whereas
two commenters stated that the flow rate should be measured at the
outlet of the water heater, expressing concern that measuring at the
inlet may be inaccurate. 87 FR 1554, 1581 (Jan. 11, 2022). The January
2022 NOPR presented DOE's exploratory test data evaluating the effect
of flow meter location on the water mass measurement (see Table III.2
of the January 2022 NOPR). DOE's testing using Coriolis flow meters on
both the inlet and outlet water lines indicated that more accurate
measurements of the mass of water delivered are obtained when the flow
meter is located in the outlet water line than when located on the
inlet line, when both results were compared to a mass scale.\62\ In
particular, the error in the UEF resulting from a mass measurement from
a flow meter at the outlet ranged between 0.002 and 0.016, whereas the
error in the UEF resulting from a mass measurement from a flow meter at
the inlet ranged between 0.023 and 0.029, depending on the type of
water heater (with DOE testing both gas-fired storage and gas-fired
instantaneous water heaters). DOE also acknowledged that third party
laboratories typically install a flow meter on the inlet side. However,
DOE did not propose a change based on this limited set of test results,
which only included one gas-fired storage water heater sample and one
gas-fired instantaneous water heater sample, and stated that more test
data are required. Id. at 87 FR1581-1582.
---------------------------------------------------------------------------
\62\ Mass of water drawn from the water heater can either be
directly measured using a mass scale, or it can be calculated by
using a flow meter to measure the volume of water moved (and
converted to mass using the density of the water). The mass scale
approach represents the actual value of the mass of water drawn,
against which the flow meter results can be compared.
---------------------------------------------------------------------------
In response to the NOPR's request for information on this issue,
AHRI stated that having the flow meter at the inlet of the water heater
avoids having debris damage the flow meters (e.g., Teflon tape debris
from the test rig can end up in the flow meter and cause damage). In
addition, AHRI commented that placing the flow meter at the outlet may
cause water mass calculation problems, because the temperature
variation is greater at the outlet, and flow meters may not be designed
to withstand these higher outlet water temperatures. Therefore, AHRI
indicated it would support the option of installing a flow meter at the
inlet. (AHRI, No. 40 at p. 2) Rheem once again noted that major third-
party testing laboratories have flow meters installed at the inlet of
the water heater and that it is likely that all certified models have
been tested with such a set-up. (Rheem, No. 31 at pp. 4-5) BWC
commented that manufacturers should still have the option to install
flow meters at the inlet to ensure accurate results and longevity of
testing equipment, as well as to avoid manufacturer burden.
Specifically, BWC indicated that manufacturers may have sophisticated
set-ups with flow meters installed at the inlet, and there could be
substantial burden with overhauling these set-ups. (BWC, No. 33 at p.
8)
Based on these comments, DOE has determined that a requirement for
flow meters to be installed at the outlet may not only require re-
testing a large number of basic models but also
[[Page 40443]]
potentially degrade the reliability of the testing rig due to debris
flowing downstream. Because there is a generally consensus among
stakeholders who commented on this issue that it is necessary to retain
the ability to install the flow meter at the inlet side, DOE is not
amending appendix E to require measurement at the outlet side. Instead,
DOE is maintaining its current provisions in sections 3 and 4 of
appendix E, which allow for the flow meter to be installed on either
the inlet or outlet side.
4. Separate Storage Tanks
Some water heaters on the market require a volume of water,
typically contained in either a storage tank (or tanks) or in a piping
distribution system of sufficient volume, to operate. These products
operate by circulating water stored either in the piping system or from
a separate tank (or multiple separate tanks) to the water heater to be
heated then back to the piping system or tank until hot water is
needed. As discussed in section III.A.4.a of this document, DOE is
adopting a definition for these products, which are termed
``circulating water heaters.'' In the January 2022 NOPR, DOE identified
two types of circulating water heater products that require a volume of
water to operate--heat pump-only water heaters that require
installation with a separate storage tank and circulating gas-fired
instantaneous water heaters that require installation with a separate
storage tank or a piping system of sufficient volume. 87 FR 1554, 1583-
1585 (Jan. 11, 2022). Circulating gas-fired instantaneous water heaters
are distinct from other types of gas-fired instantaneous water heaters
in that they are not designed to operate independent of a storage tank
or hot water system, as other gas-fired instantaneous water heaters
are. This applies generally to circulating water heaters; however, DOE
has determined that there are no electric resistance or oil-fired
circulating water heaters on the market today.
The currently applicable appendix E test procedure does not have
procedures in place to appropriately test circulating water heaters. In
the January 2022 NOPR, DOE proposed to require that circulating water
heaters be tested using an 80 gallon (1 gallon) unfired hot
water storage tank (UFHWST) that meets the energy conservation
standards for an unfired hot water storage tank at 10 CFR 431.110(a).
87 FR 1554, 1583-1585 (Jan. 11, 2022).
In response to the January 2022 NOPR, DOE received a number of
comments regarding the separate storage tank requirements, primarily
related to the 1 gallon tolerance, the representativeness
of an 80-gallon unfired hot water storage tank, and the lack of a
specification of an upper bound on thermal insulation for the unfired
hot water storage tank. These comments were discussed in detail and
addressed in the July 2022 SNOPR. Some commenters specifically
recommended that DOE specify electric storage water heaters to be
paired with heat pump-only water heaters. Commenters also raised
questions as to whether or not the separate tanks to be used during
testing may have back-up heating. For gas-fired circulating water
heaters, commenters urged DOE to consider allowing multiple tank sizes
to be used for testing rather than just the 80-gallon tank proposed in
the January 2022 NOPR. 87 FR 42270, 42281-42283 (July 14, 2022).
After considering the issues raised by commenters responding to the
January 2022 NOPR, in the July 2022 SNOPR, DOE proposed several updates
to its earlier proposals (in section 4.10 of appendix E) for testing
circulating water heaters as initially presented in the January 2022
NOPR. 87 FR 42270, 42282-42283 (July 14, 2022). These proposed
modifications to DOE's initial proposal are set forth in the paragraphs
that follow.
After re-evaluating the market for heat-pump-only water heaters,
DOE tentatively determined that testing such products with a
conventional electric storage water (i.e., an electric water heater
that uses only electric resistance heating elements) would be more
representative than testing with an UFHWST. Therefore, DOE proposed
that heat-pump-only water heaters be tested in the medium draw pattern
using a 40-gallon traditional electric storage tank (i.e., that
provides heat only with electric resistance heating elements) that has
a UEF rating at the minimum required at 10 CFR 430.32(d). DOE chose a
40-gallon tank in the medium draw pattern because that size and draw
pattern combination has the highest number of models currently
available on the market.\63\ DOE also proposed that, for heat pump-only
water heaters, the test be carried out using a tank that does not
``over-heat'' the stored water (i.e., Tmax,1 (maximum
measured mean tank temperature after cut-out following the first draw
of the 24-hour simulated-use test) must be less than or equal to
Tdel,2 (average outlet water temperature during the 2nd draw
of the 24-hour simulated-use test); see section III.E.1 of this
document for more discussion of water heater ``over-heating''). This
would ensure that the electric storage tanks are not overheating during
the test, thereby ensuring consistency across tests. 87 FR 42270, 42282
(July 14, 2022).
---------------------------------------------------------------------------
\63\ See Figure 3A.2.8 of the Preliminary Analysis Technical
Support Document for consumer water heaters (Docket No. EERE-2017-
BT-STD-0019- 0018).
---------------------------------------------------------------------------
By contrast, DOE maintained its earlier proposal that a UFHWST be
used for testing of circulating gas-fired water heaters, as those
products are more likely to be installed with a UFHWST in the field.
Therefore, DOE tentatively concluded that testing with an UFHWST would
be representative for such units. 87 FR 42270, 42282 (July 14, 2022).
In response to the January 2022 NOPR, some commenters suggested
that DOE allow manufacturers to specify the storage tank used for
testing. DOE noted that this approach could lead to additional test
burden for third-party testing laboratories, which may need to acquire
more than one storage tank if they are performing tests for multiple
manufacturers, each of whom may specify a different storage tank for
testing. In order to avoid creating the potential for additional test
burden, DOE tentatively determined not to allow manufacturers to
specify the electric storage water heater or unfired hot water storage
tank used respectively for testing the heat pump-only or gas-fired
instantaneous circulating water heaters. Additionally, DOE stated it
would consider relevant amendments to certification and reporting
requirements in a separate rulemaking. 87 FR 42270, 42282 (July 14,
2022).
After considering the comments regarding the tolerance on the
storage tank initially proposed in the January 2022 NOPR, DOE
tentatively determined in the July 2022 SNOPR that a wider tolerance
would reduce potential testing burden while still providing
representative and reproducible results. Specifically, DOE tentatively
concluded that a 10-percent tolerance would increase flexibility for
manufacturers by increasing the number of tanks that could be used for
testing, while not materially impacting the UEF test results.
Therefore, consistent with the recommendations provided by commenters,
DOE proposed to adopt a 10 percent tolerance (10 percent,
allowing products with rated storage volumes between 36 gallons and 44
gallons) for the electric storage water heater used for testing heat-
pump-only water heaters. 87 FR 42270, 42282 (July 14, 2022).
Additionally, after further review of the market for circulating
gas-fired instantaneous water heaters and unfired
[[Page 40444]]
hot water storage tanks, DOE proposed in the July 2022 SNOPR to allow
testing with a tank at any storage volume between 80- and 120-gallons.
Based on further analysis, DOE tentatively determined that variations
in the tank size should not significantly impact the result of the
test. During a water draw, the internal tank temperature decreases as
hot water exits the tank and is replenished by colder water entering
the tank. Generally, different tank sizes will result in different
rates of internal temperature decrease during a water draw (e.g.,
during a specified water draw, a smaller tank will generally experience
a faster decrease in temperature compared to a larger tank). During a
test, any potential differences in the tank water temperature due to
the use of different size tanks would be accompanied by a corresponding
proportional difference in burner on-time, such that the impact on
measured efficiency (i.e., the ratio of energy output to energy input)
would be negligible. DOE noted its recognition that a larger tank would
likely have more standby losses than a smaller tank; however, DOE
tentatively determined that the impact this would have on measure
efficiency would also not be significant. 87 FR 42270, 42282-42283
(July 14, 2022).
DOE noted that providing a range of allowable tank volumes would
reduce potential burden by providing manufacturers with more tank
options, thereby allowing them to pair their circulating gas-fired
instantaneous water heaters with an existing UFHWST model. This
approach is also likely to be more representative of how the units
would be installed in the field as opposed to testing with a custom-
made tank for testing or a competitor's tank that meets a specific
volume requirement. 87 FR 42270, 42283 (July 14, 2022).
In addition, after considering comments in response to the January
2022 NOPR, DOE tentatively determined in the July 2022 SNOPR that the
lack of an upper bound on the thermal insulation value for the UFHWST
could lead to differences in measured efficiency that reflect
differences in tank performance, rather than reflecting differences in
water heater performance. Therefore, DOE tentatively determined that
more specific constraints on tank performance are warranted to ensure
more comparable test results across the subject water heater models.
DOE proposed to require that UFHWSTs used for testing circulating gas-
fired instantaneous water heaters exactly meet the baseline energy
conservation standard for UFHWSTs.\64\ 87 FR 42270, 42283 (July 14,
2022). However, DOE did not include commenters' suggested
specifications for other tank characteristics (such as the inlet and
outlet connection locations, internal tank baffling, and inlet tube
designs) for the UFHWST because, as explained in the July 2022 SNOPR,
DOE tentatively determined that over-specifying the design of the
UFHWST--given the impacts on the UEF rating are minimal--could result
in a very narrow range of UFHWST models which could be used for testing
circulating water heaters, thereby potentially introducing significant
barriers to testing these products at third-party laboratories. In
addition, DOE tentatively concluded that it lacked sufficient
information regarding these specifications to do so. 87 FR 42270, 42283
(July 14, 2022).
---------------------------------------------------------------------------
\64\ Currently, baseline energy conservation standards for
UFHWSTs require a thermal insulation of R-12.5. 10 CFR 431.110(a).
---------------------------------------------------------------------------
Similarly, DOE proposed that the electric storage water heater used
for testing heat-pump-only water heaters have a rated UEF corresponding
to the minimum standard found at 10 CFR 430.32(d), thereby helping to
ensure more comparable results.
In summary, in the July 2022 SNOPR, DOE proposed to further amend
the separate storage tank requirements proposed in the January 2022
NOPR for heat pump-only and gas-fired circulating water heaters. DOE
proposed that heat pump-only water heaters be tested with a 40-gallon
(4 gallons) electric storage water heater that has a UEF
value corresponding to the minimum standard for such products and that
does not ``over-heat''; and that gas-fired circulating water heaters be
tested with an 80-gallon to 120-gallon unfired hot water storage tank
that is rated equal to the energy conservation standard for such
equipment.
In response to the July 2022 SNOPR, NEEA indicated support for
DOE's revisions to the proposed test procedure for circulating water
heaters. (NEEA, No. 56 at p. 2) A.O. Smith and the CA IOUs supported
DOE's proposal requiring gas[hyphen]fired circulating water heaters to
be tested using a UFHWST with a storage volume between 80 and 120
gallons and an R[hyphen]value exactly at the minimum R[hyphen]value
required at 10 CFR 431.110(a). (A.O. Smith, No. 51 at p. 8; CA IOUs,
No. 52 at p. 6) The CA IOUs also indicated support for the revision to
require heat pump circulating water heaters to use a 40-gallon electric
resistance water heater meeting the minimum UEF requirements. (CA IOUs,
No. 52 at p. 6)
AHRI stated that allowing manufacturers to specify the storage tank
used for testing circulating water heaters would not increase test
burden for third-party laboratories because manufacturers would provide
both the water heater and the storage tank it was designed to be used
with to the laboratories. (AHRI, No. 55 at pp. 5-6) BWC suggested that
the capacity range of 80 to 120 gallons for UFHWSTs used to test
circulating water heaters is too wide to ensure consistent results, so,
therefore, the commenter requested that DOE complete further testing to
validate it. (BWC, No. 48 at p. 4)
After considering these comments, DOE has concluded that providing
a range of allowable tank volumes for use with circulating gas-fired
instantaneous water heaters as described in the July 2022 SNOPR would
reduce potential burden by providing manufacturers with more tank
options, thereby allowing them to pair their circulating gas-fired
instantaneous water heaters with an existing UFHWST model. This
approach balances manufacturer burden (by allowing flexibility in the
tank size) with ensuring reproducibility of test results (by limiting
the options to a fixed range of sizes). In response to AHRI's comments,
DOE notes that it is not adopting changes to the certification
requirements in this final rule, and whether or not manufacturers may
specify a specific model of UFHWST is an issue out of the scope of this
test procedure rulemaking and will be addressed in a future rulemaking
addressing certification requirements for consumer water heaters.
As such, in this final rule, DOE is adopting the separate storage
tank requirements for circulating gas-fired instantaneous water heaters
as proposed in the July 2022 SNOPR. In response to BWC's comment, DOE
understands that the choice of tank size may result in slightly
different ratings for these products, and BWC seeks to determine how
much variability in results there would be if testing were to be
conducted with an 80-gallon UFHWST versus a 120-gallon UFHWST. However,
the Department's approach is instead to permit manufacturers some
flexibility in testing options so as to be able to tailor the tank
pairing to the design or application intent of the circulating water
heater, and to then subsequently account for the variation in ratings
when setting amended standards for circulating water heaters by having
the required UEF be a function of the effective volume. As discussed in
section III.I of this document, compliance with the separate storage
tank test method will not be required
[[Page 40445]]
until compliance with amended energy conservation standards is
mandatory, if such standards are adopted. Additionally, section
III.F.2.b of this document describes the use of the effective storage
volume metric to be able to associate efficiency ratings to the storage
tank size for circulating water heaters. This matter is discussed
further in this section in response to other comments. In taking these
steps, DOE can, in the ongoing standards rulemaking for consumer water
heaters, propose and request comment on new energy conservation
standards for circulating water heaters that are functions of the
effective storage volume.
SMTI requested that DOE widen the accepted volume range for
electric storage tanks used to test separate heat pump-only water
heaters based on the performance requirements of each product instead
of requiring that all products be tested with a 40-gallon tank. (SMTI,
No. 49 at p. 1) SMTI suggested that heat pump-only water heaters be
tested with manufacturer-specified storage tanks, which the
manufacturer would provide to third-party laboratories, and that a 40-
gallon tank be used if a specific storage tank is not specified. (SMTI,
No. 49 at p. 2) A.O. Smith stated that there is insufficient data to
conclude that the 40-gallon electric resistance water heater should be
used for testing heat-pump-only or split-system water heaters and that
a 50-gallon electric resistance water heater may be more representative
based on manufacturer data. (A.O. Smith, No. 51 at p. 9) However, A.O.
Smith did not provide any manufacturer data to support its claim that a
50-gallon electric resistance water heater would be more
representative.
As described in the July 2022 SNOPR, DOE selected a 40-gallon tank
in the medium draw pattern because that size and draw pattern
combination has the highest number of models currently available on the
market as observed in models currently certified to DOE's Compliance
Certification Database (see Figure 3A.2.8 of Preliminary Analysis TSD).
87 FR 42270, 42282 (July 14, 2022). This finding has not changed since
the publication of the July 2022 SNOPR, and on this basis (because
additional data were not provided by stakeholders), DOE has concluded
that this tank size and draw pattern are the most representative choice
to be paired with a heat pump-only water heater. In response to SMTI's
request to widen the volume range, DOE has determined to adopt a volume
tolerance of 5 gallons, as opposed to 10% (4
gallons) which was proposed in the July 2022 SNOPR. This change is
based on further inspection of the rated storage volumes of electric
storage water heaters which have a nominal capacity of ``40 gallons''
as observed in models certified to DOE's Compliance Certification
Database. As such, DOE does not expect the difference to be substantial
in impacting energy efficiency results for circulating heat pump water
heaters because the volume range covers products of the same nominal
volume. As previously stated in response to a comment made by AHRI, DOE
is allowing manufacturers to specify an effective storage volume for
the tank rather than a specific model because any characteristics of
the tank that would affect the efficiency rating of the circulating
water heater during a test are accounted for in the volume and
efficiency rating (in this case, UEF) of the tank.
AHRI and BWC indicated that DOE's primary TSD for energy
conservation standards for consumer water heaters suggests that the 40-
gallon electric resistance water heaters used to test heat-pump-only
water heaters may be phased out by future DOE regulations. (AHRI, No.
55 at p. 5; BWC, No. 48 at pp. 4-5) Rheem supported AHRI's comment on
this issue. (Rheem, No. 47 at p. 5)
In response, DOE notes that the current energy conservation
standards rulemaking for consumer water heaters is still ongoing, and
any preliminary results published as part of that rulemaking are
neither final nor binding in any way. Consequently, it is not confirmed
that electric resistance storage water heaters will be phased out.
Nevertheless, to ensure there will be no confusion in the event such
regulatory changes were to occur, DOE is removing the requirement that
the storage tank use only electric resistance heating elements.
Accordingly, the associated portion of section 4.10 of appendix E has
been updated to read as follows:
``When testing a heat pump circulating water heater, the tank to be
used for testing shall be an electric storage water heater that has a
measured volume of 40 gallons (5 gallons), has a First-Hour
Rating greater than or equal to 51 gallons and less than 75 gallons
resulting in classification under the medium draw pattern, and has a
rated UEF equal to the minimum UEF standard specified at 10 CFR
430.32(d), rounded to the nearest 0.01. The operational mode of the
heat pump circulating water heater and storage water heater paired
system shall be set in accordance with section 5.1.1 of this
appendix.''
In its comments on the July 2022 SNOPR, A.O. Smith supported
ensuring that non[hyphen]unitary heat pump water heaters \65\ intended
for use in a single[hyphen]family home or an individual dwelling unit
that need to be paired with a separate storage tank are tested and
certified to the Department consistent with appendix E. (A.O. Smith,
No. 51 at pp. 8-9) A.O. Smith also requested that DOE clearly define
the test apparatus for heat pump circulating water heaters. (A.O.
Smith, No. 51 at p. 9)
---------------------------------------------------------------------------
\65\ DOE understands ``non-unitary heat pump water heaters'' to
refer to products which consist of a heat pump system to heat water
but are not packaged with the rest of the components used in
domestic hot water production (i.e., a hot water storage tank).
These products are considered circulating heat pump water heaters in
this rulemaking.
---------------------------------------------------------------------------
In response to concern from certain stakeholders, DOE will allow
manufacturers of gas-fired circulating water heaters to represent
thermal efficiency test results measured according to the commercial
water heaters test procedure outlined at 10 CFR part 431, subpart G, in
addition to the required UEF test results. DOE also notes that this
final rule clearly defines the test apparatus for circulating heat pump
water heaters in section 4.10 of the amended appendix E.
Rheem reiterated its request for clarification as to whether a
system (i.e., a heat pump and storage tank designed to be used
together) can be certified independent of the proposed method to use a
specific storage tank or electric resistance water heater. (Rheem, No.
47 at p. 5) Rheem also requested that DOE address whether a split-
system water heater, designed to be used with an 80-gallon tank, can
have a storage tank with electric resistance elements and whether a
replacement tank can be sold. (Rheem, No. 47 at p. 5)
In response to Rheem, DOE would clarify that a product which
consists of a heat pump and a storage tank designed to be used together
and are sold together would constitute a ``split-system heat pump water
heater.'' Such a system would be certified altogether as an electric
storage water heater, and there would be no need to use the test
procedure provisions for a separate storage tank. If the heat pump
module were sold separately and independent of the tank, then it would
constitute a ``circulating heat pump water heater,'' and the test
procedure provisions for a 40-gallon 5 gallon separate
storage water heater would then apply. In Rheem's example of a product
with an 80-gallon storage tank, that configuration would constitute a
``split-
[[Page 40446]]
system heat pump water heater''--an electric storage water heater with
a storage volume of 80 gallons. The separate storage tank provisions do
not apply to such a product. The 80-gallon storage tank component of
the split-system heat pump water heater may have electric resistance
back-up elements. Replacement storage tanks sold on a separate basis--
essentially an electric resistance water heater with a storage volume
of 80-gallons--would not be permitted, because electric resistance
heating elements would not be able to achieve the UEF energy
conservation standard levels mandatory for electric storage water
heaters greater than 55 gallons for which compliance is currently
required (see 10 CFR 430.32(d)).
In response to the January 2022 NOPR, A.O. Smith also commented
that the energy from a circulating pump should be used in the UEF
calculations and that the flow rates between the circulating heat pump
water heater and the storage tank should be specified by the
manufacturer. (A.O. Smith, No. 37 at p. 3) DOE agrees that including
the energy use of the circulating pump is appropriate and consistent
with the currently applicable appendix E test procedure, which requires
measurement of power consumption of auxiliary electricity-using
components. In this final rule, for water heaters which require
separate storage tanks, the power consumption of the circulating pump
shall be directly metered if the pump is integrated into the water
heater. Section 4.10 of the amended appendix E test procedure will
require that if the water heater is supplied with a separate, non-
integrated circulating pump, it is to be installed as per the
manufacturer's installation instructions, and its power consumption
will similarly be accounted for in the energy measurements to determine
UEF.
In conclusion, after considering comments received in response to
the January 2022 NOPR and the July 2022 SNOPR, DOE is adopting the
requirements for separate storage tanks as discussed in this final
rule.
DOE's previous proposals involving the use of separate storage
tanks did not specify a test procedure by which the storage volume of
unfired hot water storage tanks paired with circulating water heaters
to determine efficiency is to be measured. It is important to obtain a
precise measurement of the storage volume of the UFHWST because its
physical size affects the measured efficiency of the water heater due
to standby losses of heat from the stored water to the air surrounding
the storage tank; these standby losses increase as the size of the tank
increases.
To ensure the accuracy and repeatability of test results, DOE is
amending sections 4.10 and 5.2.1 of appendix E so that the method for
determining storage tank volume specified in section 5.2.1 must also be
conducted to verify the volume of unfired hot water storage tanks used
to test circulating water heaters. In this method, storage volume is
determined in gallons by subtracting the tare weight, measured while
the tank is dry and empty, from the weight of the system when filled
with water and dividing the resulting net weight of water by the
density of water at the measured water temperature. This method is
consistent with how the volume of unfired hot water storage tanks is
currently rated. It is also the method specified for storage-type and
storage-type instantaneous commercial water heaters under subpart G to
10 CFR part 431.
Additionally, as discussed in section III.F.2.b of this document,
DOE is establishing that the effective storage volume of a circulating
water heater is equivalent to the measured storage volume of the
separate storage tank which was used during testing of the circulating
water heater. This alleviates the manufacturers' concerns by ensuring
that the standby losses reflected in the UEF rating of the circulating
water heater can be mapped to the volume of the separate storage tank
which was used during testing without having to specify a particular
model of tank, for example. DOE would consider this tank volume in the
development of energy conservation standards for circulating water
heaters.
E. Test Conduct
As discussed throughout this rulemaking, EPCA requires that any
test procedures prescribed or amended under this section shall be
reasonably designed to produce test results which measure energy
efficiency, energy use, or estimated annual operating cost of a covered
product during a representative average use cycle (as determined by the
Secretary) or period of use and shall not be unduly burdensome to
conduct. (42 U.S.C. 6293(b)(3)) The proposed changes to test conduct,
along with specific stakeholder comments received and DOE's responses,
are discussed further in the subsections that immediately follow.
1. High Temperature Testing
Certain electric storage water heaters on the market are capable of
raising the temperature of the stored water significantly above the
outlet water temperature requirements specified in section 2.4 of
appendix E, while still delivering water at a lower temperature that is
at or near the temperature specified in appendix E. The storage tank is
heated to a temperature which is still within the normal operating
range of the water heater, but a mixing valve is typically installed
with these products (either integrated into the water heater by the
manufacturer at the factory, or added to the water heater in the field
by the installer) to temper the outlet water to a more typical delivery
temperature. (Set-up requirements for mixing valves that are to be used
during testing are discussed in section III.D.2 of this final rule.)
When the outlet water is tempered like this, a smaller amount of the
hot water from the tank is required to meet demand (because the water
in the tank is hotter than desired). Because less water needs to be
removed from the tank, the effect of a mixing valve is to increase the
amount of hot water that can be delivered overall by the water heater.
In addition to determining the set-up considerations to test these
products in a representative manner, DOE must consider the impact of
raising the storage tank temperature significantly above the setpoint
outlet temperature (i.e., ``storage tank overheating'') on the
efficiency of a water heater since this represents how the water heater
will be used in the field.
As discussed in the July 2022 SNOPR, storage tank overheating
increases the amount of hot water that a given size water heater can
deliver. 87 FR 42270, 42277-42278 (July 14, 2022).
Historically, it has not been uncommon for water heaters to come
with the capability to adjust the settings to increase the temperature
of the water being stored in the tank, although, it is DOE's
understanding that in the past, consumers rarely modified the
preconfigured settings on their storage tanks. However, DOE has
recently become aware of products that are being marketed to consumers
with ``capacity boosting'' capabilities so as to avoid the need to
install a larger storage-type water heater. The products (that DOE
addressed in the July 2022 SNOPR) are equipped with user-operable modes
which set the water heater to boost the storage tank temperature and
use a built-in mixing valve (or one installed at the point of
manufacture) to automatically maintain the delivery temperature. For
example, one manufacturer produces 30-, 40-, and 50-gallon water
heaters with an ``X-High Setting'' claiming to provide the same amount
of hot water (``Effective Capacity,'' as the manufacturer refers to
[[Page 40447]]
it) as significantly larger water heaters with a more typical storage
tank temperature of 125 [deg]F--such as an 80-gallon capacity for the
50-gallon model, 64-gallon capacity for the 40-gallon model, and 48-
gallon capacity for the 30-gallon model.\66\ DOE notes that the 40-
gallon model and the 50-gallon model are capable of providing effective
capacities greater than 55 gallons, which, based on effective capacity,
would put these models into a different product class. (see 10 CFR
430.32(d)). Another manufacturer produces a 55-gallon water heater with
a variety of settings allowing the user to get ``performance
equivalency'' of a 65-, 80-, or 100-gallon tank, stating that the tank
raises the temperature safely up to 170 [deg]F.\67\ Again, these
increased capacities would put this model into a different product
class.
---------------------------------------------------------------------------
\66\ See, for example: www.geappliances.com/appliance/GE-Smart-50-Gallon-Electric-Water-Heater-with-Flexible-Capacity-GE50S10BMM
(Last accessed April 14, 2023).
\67\ For example, DOE's Compliance Certification Database
includes a 107-gallon electric storage water heater with an FHR of
94 gallons.
---------------------------------------------------------------------------
As stated in the July 2022 SNOPR, consumers would be expected to
use the over-heated mode as part of the regular operation of their
water heater. Accordingly, for such products, DOE expects that a
representative average use cycle would include some portion of time in
over-heated mode. 87 FR 42270, 42279 (July 14, 2022). For these water
heaters, DOE believes that a representative average use cycle in the
test procedure must encompass the ''capacity boosting'' capability, as
this is the mode that DOE believes the consumer will likely be using
once installed in the field, because such purchases are likely
predicated on this capacity-boosting capability.
The operational mode selection instructions in section 5.1 of
appendix E do not specifically address the situation when a water
heater has this type of operational mode that boosts the capacity. In
response to the January 2022 NOPR, several commenters requested that
DOE consider amendments to the appendix E test procedure to provide
more representative efficiency results (including ways to account for
the increased effective capacity) for these products that ``overheat''
the stored water beyond the delivery temperature. After considering
these comments in the July 2022 SNOPR, DOE proposed to establish
additional requirements for the testing of water heaters which have
these operational modes. 87 FR 42270, 42278 (July 14, 2022).
In order to further examine the potential impacts of storing water
at temperatures higher than the delivery temperature, DOE performed
testing on one 50-gallon electric resistance storage water heater that
includes a built-in mixing valve and multiple user-selectable modes to
boost the delivery capacity through storage tank overheating. As
described in the July 2022 SNOPR, DOE collected data at three different
storage tank temperatures, each of which provided an outlet water
temperature at 125 [deg]F 5 [deg]F through the use of the
built-in mixing valve. DOE compared the maximum measured mean tank
temperature after cut-out following the first draw of the 24-hour
simulated-use test (Tmax,1) to the average outlet water
temperature during the second draw (Tdel,2) as an indicator
of the degree of ``overheating.'' DOE's test data is provided in Table
III.3 of the July 2022 SNOPR. 87 FR 42270, 42278-42279 (July 14, 2022).
The test results indicated that storage tank overheating clearly
leads to an increase in the measured FHR value. The test configuration
corresponding to the current DOE test procedure produced an FHR value
of 77 gallons. The overheated configurations with mean tank
temperatures of 144.5 and 159.6 produced FHR values of 81 and 95
gallons, respectively. DOE notes that an FHR of 95 gallons is
comparable to that of a 100-gallon electric storage water heater.\68\
However, increasing the temperature of the stored water can reduce
energy efficiency because the hotter tank undergoes substantially
higher standby energy losses. As shown in Table III.3 of the July 2022
SNOPR, DOE's test data show that at a tank temperature of 124.3 [deg]F,
the measured UEF is 0.94, which is compliant with the current
standards. When the temperature is increased to 144.5 [deg]F, the UEF
decreases to 0.90. Further increasing the temperature to 159.6 [deg]F
decreases the UEF to 0.88. 87 FR 42270, 42279 (July 14, 2022).
---------------------------------------------------------------------------
\68\ For example, DOE's Compliance Certification Database
includes a 107-gallon electric storage water heater with an FHR of
94 gallons.
---------------------------------------------------------------------------
All of the tested temperatures correspond to normal operational
modes for the water heater, and a review of publicly-available product
literature indicates that products that utilize storage tank
overheating generally offer user-selectable operational modes that
result in stored water temperatures ranging from 100 [deg]F to 170
[deg]F. Consumers who choose to use a high-capacity (i.e.,
``overheated'') mode will experience the water heater performing
significantly worse in terms of its energy efficiency rating than if
the rating were determined based on testing without storage tank
overheating. In other words, the rated efficiency at the rated delivery
capacity would not be representative of an average use cycle or period
of use when operated in a high-capacity mode. 87 FR 42270, 42279 (July
14, 2022).
In the July 2022 SNOPR, DOE surmised that consumers who purchase a
water heater that provides overheating capability would do so with the
intent to use such capability; as such, these consumers would be
expected to use the over-heated mode some portion of the time, ranging
from occasional use (e.g., switching between the normal mode and the
overheated mode depending on the hot water capacity needed at any
particular time) to regular use. Accordingly, for such products, DOE
expects that a representative average use cycle would include some
portion of time in overheated mode. For this reason, DOE tentatively
determined that testing storage-type water heaters that offer user-
selectable overheated modes in the overheated mode would provide a more
representative result than testing in the default mode. Therefore, DOE
proposed to amend section 5.1 of appendix E to require that for water
heaters that offer a user-selected operational mode(s) in which the
storage tank is maintained at a temperature higher than the delivery
temperature, the operational mode shall be that which results in the
highest mean tank temperature while maintaining an outlet temperature
of 125 [deg]F 5 [deg]F. Because this amendment would change
the measured energy efficiency, DOE proposed that compliance with this
requirement would not be necessary until the compliance date for
amended energy conservation standards. 87 FR 42270, 42279 (July 14,
2022).
As explained in the July 2022 SNOPR, demand-response water heaters
with the capability to undergo utility-initiated overheating would not
be expected to increase the capacity of the water heater over a typical
average use cycle in the same way that a water heater with user-
initiated overheating would, so DOE had tentatively concluded that
testing demand-response water heaters in the default/normal would be
the most representative method for those products. Therefore, DOE
proposed to define ``demand-response water heater'' (see section
III.A.1 of this document) and exclude such products from the
requirement to test in the operational mode that results in the highest
mean tank temperature while maintaining an
[[Page 40448]]
outlet temperature of 125 [deg]F 5 [deg]F, even if they are
capable of overheating the stored water. 87 FR 42270, 42280 (July 14,
2022).
In response to the July 2022 SNOPR, BWC stated that the phrase
``storage tank overheating'' may be confusing to consumers and
suggested that DOE find an alternate phrase to describe this concept
(i.e., ``water heaters with high heat modes''). (BWC, No. 48 at p. 3)
GEA also disagreed with DOE's use of the term ``over-heating'' to refer
to water heaters that can deliver water at lower temperature than that
at which it is stored, suggesting ``delivery-control'' as an
alternative, given that these products heat in the manner intended.
(GEA, No. 53 at p. 2) In response to these comments and acknowledging
the sensitivity around the potentially negative connotation of the term
``overheating,'' as noted earlier in this document, DOE's use of the
term ``overheating'' does not denote performance outside of the normal
operating range of the water heater, but rather refers to raising the
tank temperature above the outlet water setpoint. To avoid any
potential confusion, DOE will hereinafter refer to water heaters with
overheating capability as water heaters with ``high heat modes.''
The following subsections summarize the remaining comments received
in response to the provisions proposed in the July 2022 SNOPR for water
heaters with high heat modes and include DOE's additional assessments
of the impact on UEF ratings, representativeness of the test method,
and implications for compliance with standards associated with high
temperature testing.\69\ As discussed in the following subsections, DOE
has concluded that including test conduct provisions for determining
the ratings of water heaters tested using the high temperature testing
method would be justified. Therefore, in this final rule, DOE is
establishing the methodology for determining ratings for electric
resistance storage water heater using high temperature testing in
appendix E, but DOE is allowing voluntary representations at this
point. Specifically, manufacturers may opt to use the high temperature
test method in addition to the regular temperature setting test method
if they desire to make voluntary representations of the efficiency when
tested in high temperature mode. DOE will consider establishing
requirements for which electric resistance storage water heaters must
be tested and represented according to the method for high temperature
testing in its ongoing energy conservation standards rulemaking for
consumer water heaters. Until such time, the regular test method is
mandatory for compliance with the current Federal energy conservation
standards.
---------------------------------------------------------------------------
\69\ DOE is establishing a method for testing water heaters at
an elevated tank temperature, including water heaters without ``high
heat modes.'' Therefore, DOE refers to water heaters with a built-in
mixing valve and operational mode for overheating the water in the
tank as water heaters with ``high heat modes'' but refers to the
testing of water heaters at elevated storage water temperatures as
``high temperature testing.''
---------------------------------------------------------------------------
a. Impact on UEF Ratings
In response to the July 2022 SNOPR, ASAP, ACEEE, and NRDC expressed
support for DOE's proposal for addressing storage-type water heaters
that heat the stored water beyond the delivery temperature. (ASAP,
ACEEE, and NRDC, No. 54 at p. 2)
NEEA supported DOE's proposal to test water heaters in a user-
selectable ``overheat'' mode when such a mode is available, as well as
DOE's proposed methodology for identifying ``overheat'' modes. NEEA
also indicated that it had performed testing on two 120-volt heat pump
water heater models which had these modes available, and its test
results showed a significant reduction in efficiency when the water
heater was set to store water at an elevated temperature of 140
[deg]F.\70\ Thus, NEEA stated that requiring testing in the
``overheat'' mode would help realize the energy and cost savings
intended with efficiency standards. (NEEA, No. 56 at p. 2)
---------------------------------------------------------------------------
\70\ An August 30, 2022 report by NEEA containing test data for
these water heaters can be found online at: neea.org/resources/plug-in-heat-pump-water-heaters-an-early-look-to-120-volt-products (Last
accessed on Nov. 22, 2022).
---------------------------------------------------------------------------
BWC disagreed that water heaters with high heat modes should have
separate testing requirements and expressed concern that tests to
examine the potential effects of heating stored water above the
delivery temperature setpoint were conducted on a single 50-gallon
electric resistance storage water heater. BWC urged DOE to conduct
further testing before finalizing this proposal. (BWC, No. 48 at p. 3)
In response, DOE notes that the UEF ratings of products which store
water at higher temperatures will be lower due to the higher standby
losses incurred as a result of this high temperature storage. DOE did,
however, conduct additional testing (see section III.F.2 of this
document) to determine that the method of determining effective storage
volume from the high temperature testing will only affect products
which significantly increase capacity by increasing storage
temperature.
Additionally, DOE reviewed the heat pump water heater test data
referenced in NEEA's comment. NEEA tested two 50-gallon 120-volt heat
pump water heaters at two storage setpoint temperatures (i.e., 125
[deg]F and 140 [deg]F), with mixing valves installed to temper the
delivery to 120 [deg]F. NEEA's report concludes that the recovery
efficiency can decrease by a factor of 3 to 8 percent when the setpoint
temperature is increased from 125 [deg]F to 140 [deg]F. The higher
setpoint temperature resulted in an increase in FHR of approximately 13
gallons. NEEA's report also states that at 67.5 [deg]F ambient air, an
increase in the setpoint temperature could increase standby losses by
25 percent, although NEEA stated that standby losses contribute less to
the overall energy consumption of a heat pump water heater compared to
recovery periods. DOE notes that NEEA did not conduct standby loss
testing or present the UEF results of these water heaters in each mode.
DOE expects that the standby loss from having a higher setpoint
temperature would have a more significant impact on electric resistance
water heaters because the recovery efficiency of electric resistance
heating is not affected by the water temperature.\71\ However, in
conjunction with DOE's own test data (which was obtained through full
24-hour simulated use test measurements of an electric resistance
storage water heater), DOE has determined that high temperature testing
would result in significantly lower UEF results compared to setting the
tank temperature close to the delivery setpoint of 125 [deg]F.
---------------------------------------------------------------------------
\71\ Section 6.3.2 of the currently applicable appendix E test
procedure (which will be re-located to section 6.3.3 upon the
effective date of this final rule) states that the recovery
efficiency for electric water heaters with immersed heating
elements, not including heat pump water heaters with immersed
heating elements, is assumed to be 98 percent.
---------------------------------------------------------------------------
Given the significant difference in UEF performance that have been
observed based on the temperature of the water stored in the tank, DOE
has concluded it is appropriate to provide a method to conduct high
temperature testing. Section III.E.1.d of this document describes how
DOE is establishing the requirements for high temperature testing. Due
to the expected impacts of high temperature testing on UEF, DOE will
not require compliance with this test method until compliance with
amended energy conservation standards accounting for such water heaters
is also required.
[[Page 40449]]
b. Demand-Response Water Heaters
As discussed previously, in the July 2022 SNOPR, DOE proposed to
define ``demand-response water heater'' and exclude such products from
the proposed requirement to test in the operational mode that results
in the highest mean tank temperature while maintaining an outlet
temperature of 125 [deg]F 5 [deg]F, even if they are
capable of heating the stored water above the delivery temperature. 87
FR 42270, 42280 (July 14, 2022).
In response to the July 2022 SNOPR, NYSERDA indicated that water
heaters with demand-response functionality should be excluded from
testing at the highest tank temperature available. (NYSERDA, No. 50 at
p. 3) A.O. Smith agreed with DOE's assessment that demand-response
water heaters need the operational capability to ``over[hyphen]heat''
the stored water in the tank above the intended outlet water
temperature in response to a signal or command from a utility or
third[hyphen]party aggregator. The commenter stated that these load-up
events are typically short in duration and do not keep the stored water
in an over-heated state continuously or permanently. However, A.O.
Smith raised concerns about the impact of this proposed amendment on
the availability of the high heat mode feature on non-demand-response
products. A.O. Smith urged DOE to continue to allow non-demand-response
heat pump water heaters with selectable high heat modes to retain this
functionality for customer utility. (A.O. Smith, No. 51 at pp. 5-6)
In contrast, the CA IOUs suggested that demand-response capable
water heaters should be subject to the same test procedure as other
water heaters capable of operating in high heat modes. (CA IOUs, No. 52
at p. 6)
As noted in section III.A.1 of this document, DOE is not
establishing a definition for ``demand-response water heater'' in this
final rule in order to prevent potential industry confusion from
arising due to any differences in the features requirements specified
in such definition. However, DOE has found it appropriate to still
consider factors which would help to determine whether it is most
representative to require demand-response water heaters to test at the
highest tank temperature setting.
As described in the July 2022 SNOPR and discussed in section
III.A.1 of this document, high-temperature water storage occurring in
demand-response water heaters and initiated by the electric utility
serves an important purpose for energy storage and grid flexibility. 87
FR 44270, 42279-42280 (July 14, 2022). Additionally, DOE noted that
demand-response water heaters do not perform this action to increase
the overall daily capacity of the water heater. Instead, the capacity
is only temporarily boosted to counteract the deactivation of the
heating elements for extended periods of time when demand curtailment
is occurring. As such, demand-response water heaters with the
capability to undergo only utility-initiated high heat modes would not
be expected to increase the capacity of the water heater over a typical
average use cycle in the same way that a water heater with the ability
to have the user increase the storage tank temperature would. Id.
To reiterate, EPCA requires that any test procedures prescribed or
amended shall be reasonably designed to product test results which
measure energy efficiency, energy use, or estimated annual operating
cost of a covered product or equipment during a representative average
use cycle or period of use and not be unduly burdensome to conduct. (42
U.S.C. 6293(b)(3); 42 U.S.C. 6314(a)(2)). Thus, DOE must determine
whether testing at the highest tank temperature setting during the
delivery capacity test and the 24-hour simulated-use test is
representative of an average use cycle for a demand-response water
heater. Based on information collected during this rulemaking,
including the comment from NYSERDA, demand-response water heaters do
not typically remain in a high-temperature storage state for the
entirety of a 24-hour average use cycle. The additional energy used and
stored when this type of water heater increases the tank temperature is
offset by significant periods of low energy usage such that, over a 24-
hour average use cycle, the total energy stored and consumed by the
water heater is similar to that for a product which maintains a normal
storage tank temperature throughout the day.
In response to A.O. Smith's concern about non-demand-response water
heaters, as discussed in further detail in sections III.E.1.c and
III.E.1.d of this document, DOE notes that the provisions finalized in
this rulemaking do not require high temperature testing for any water
heaters in particular at this time and, therefore, would not preclude
the possibility of non-demand-response heat pump water heaters having
user-selectable high heat modes. DOE will consider these concerns
further at such time as it proposes to require high temperature testing
for certain types of water heaters in a future rulemaking.
c. Representativeness of Field Use
AHRI indicated that additional operational modes to heat water
above 125 [deg]F are not meant to be the primary mode of operation and
should not be used continuously. AHRI stated that the proposal in the
July 2022 SNOPR to test water heaters with these modes at the settings
providing the highest internal tank temperature does not reflect the
purpose of these modes, and that proposal would require more test data
than provided in the NOPR to understand its consequences. For these
reasons, AHRI requested that DOE retract this proposal from the current
rulemaking and address it at a later time. (AHRI, No. 55 at p. 6)
Similarly, Rheem requested that DOE not consider water heaters with a
temporary, non-default high heat mode as being water heaters with high
heat modes and that DOE not include any changes related to high heat
modes in the final rule. (Rheem, No. 47 at p. 6)
GEA argued that the essential function of ``delivery-control''
water heaters is no different than a consumer who sets their standard
storage water heater to a higher temperature and regulates water
temperature at the tap by mixing in cold water. GEA added that
``delivery-control'' water heaters provide practical energy savings
benefits not captured by the consumer water heater test procedure, and
that these energy savings benefits mitigate against requiring testing
at the maximum tank storage temperature. Specifically, GEA described a
use case where a consumer may use a ``delivery-control'' water heater
in a high heat mode on occasion when more guests are in the home, which
they suggested would, on balance, use less energy as compared to full
time use of a water heater with an oversized storage capacity. (GEA,
No. 53 at p. 3)
GEA suggested that many consumers already set their storage water
heater to temperatures above 140 [deg]F and that ``delivery-control''
water heaters simply allow consumers to do so in a safer way by
premixing to a lower temperature, adding that such water heaters should
not be penalized through efficiency ratings for providing a safety
feature to prevent scalding. (GEA, No. 53 at p. 3)
GEA stated that DOE has provided no evidence that setting
``delivery-control'' water heaters at their maximum storage temperature
is a ``representative average use cycle or period of use'' as required
by EPCA at 42 U.S.C. 6293(b)(3). GEA also noted that many other
products regulated under EPCA have modes that allow for increased or
decreased energy consumption relative to their default
[[Page 40450]]
setting but that these modes are not included in their respective DOE
test procedures because they have not been deemed representative of an
average use cycle. (GEA, No. 53 at p. 4)
NYSERDA recommended that all water heaters with the option to
elevate the tank temperature, except those with demand-response
functionality, should be tested at the highest tank temperature
available, as thermostatic mixing valves are regularly installed in the
field. (NYSERDA, No. 50 at p. 3) The CA IOUs also commented that
external mixing valves are readily available to consumers, and in at
least one State (Vermont), they are required for all residential water
heater installations. Therefore, the CA IOUs urged DOE to consider
changes to its regulations that would further incentivize installers
and consumers to minimize installation costs at the expense of energy
efficiency. (CA IOUs, No. 52 at p. 5) GEA stated that thermostatic
mixing valves can be integrated into a product at the factory or added
as an accessory at a consumer's home and suggested that if
manufacturers are required to make ``inaccurate'' representations of
energy consumption for mixing valves integrated at factories, more
mixing valves will be sold as accessories, because consumer demand for
flexibility and safety will not change. (GEA, No. 53 at p. 4)
As previously discussed in the July 2022 SNOPR and in response to
the comments of AHRI and Rheem, DOE expects that consumers who purchase
a water heater with high heat modes intend to use it in order to meet
hot water demands; therefore, testing these water heaters using only
the default operational mode would not be representative of the
product's energy consumption over an average use cycle. 87 FR 42270,
42279 (July 14, 2022). From its review of product literature, DOE has
found that manufacturers of water heaters with high heat modes market
these products as smaller storage water heaters which provide the
delivery capacities of larger storage water heaters, and consumers may
opt to install a smaller water heater with high heat mode in lieu of a
larger water heater as a result (e.g., if a larger water heater does
not fit in the installation space). As such, in order to yield
efficiency results that would be most representative of the product's
enhanced delivery capabilities, DOE has concluded that it would be
necessary to include a high temperature testing method.
In light of these comments, DOE has determined that the ability to
operate with an elevated tank temperature is not limited to products
with built-in mixing valves and user-selectable capacity boosting
settings. DOE agrees with commenters that a product with a field-
installed mixing valve and the storage tank manually set to a higher
temperature could operate in much the same way, and that this practice
may be prevalent given how readily available separate mixing valves are
to consumers. As a result of these considerations, DOE concludes that
it is possible such testing could be appropriate for models capable of
heating and storing water above the delivery temperature specified in
the test method while still delivering water at the setpoint
temperature of 125 5 [deg]F. Thus, DOE is not limiting the
high temperature testing method only to products with a specific
capacity boosting mode. In other words, manufacturers may optionally
apply the high temperature test method to electric resistance storage
water heaters with the capability to heat and store water above the
delivery setpoint temperature of 125 5 [deg]F, including
products that would require a field-installed mixing valve to do so.
The provisions for high temperature testing adopted by this final
rule complement the existing operational mode selection requirements,
which, generally, would require water heaters to be set to a ``normal''
storage tank temperature close to the delivery setpoint of 125 [deg]F
(see section 5.2.1 of the currently applicable appendix E test
procedure). Specifically, the high temperature testing provisions
require setting the water heater to the highest storage tank
temperature and installing a separate mixing valve to temper the
delivery water to the outlet water requirements for products that do
not already have a mixing valve installed. If the product is equipped
with a built-in mixing valve, then the water heater's storage tank
temperature shall be set to the highest temperature which allows the
built-in mixing valve to deliver water in accordance with the outlet
water requirements.
d. Use of High Temperature Testing
In response to the July 2022 SNOPR, NEEA agreed with DOE's proposal
to implement this testing requirement only upon adoption of new
standards. (NEEA, No. 56 at p. 2) A.O. Smith supported the Department's
position that the effective date of the proposed changes to the test
procedure covering user[hyphen]selectable over-heat modes for
non[hyphen]demand-response water heaters should coincide with the
compliance date of any amendments to the energy conservation standards
for consumer water heaters. (A.O. Smith, No. 51 at p. 6)
Rheem stated that DOE's proposal to delay testing until amended
standards are required may not align with EPCA at 42 U.S.C 6293(c)(2)
\72\ and requested clarification on DOE's interpretation of this
statutory provision. (Rheem, No. 47 at p. 5) Rheem also requested DOE's
interpretation of the 42 U.S.C. 6293(e)(2) requirement to ``amend the
applicable energy conservation standard during the rulemaking carried
out with respect to such test procedure'' with respect to water heaters
with high heat modes because the amended test procedure will alter
their measured efficiency. (Rheem, No. 47 at p. 5)
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\72\ Under 42 U.S.C. 6293(c)(2), the statute provides that
effective 180 days after an amended or new test procedure applicable
to a covered product is prescribed or established under paragraph
(b) of this section, no manufacturer, distributor, retailer, or
private labeler may make any representation--(A) in writing
(including a representation on a label); or (B) in any broadcast
advertisement, with respect to energy use or efficiency or, in the
case of showerheads, faucets, water closets, and urinals, water use
of such product or cost of energy consumed by such product, unless
such product has been tested in accordance with such amended or new
test procedure and such representation fairly discloses the results
of such testing.
---------------------------------------------------------------------------
In response to Rheem's questions regarding the relevant statutory
provisions at 42 U.S.C. 6293(c)(2) and (e)(2), DOE has concluded that
the Department's approach comports with both of these EPCA provisions.
To recap, as discussed in section III.I of this document, DOE is not
requiring compliance with the high temperature testing provisions until
compliance with amended energy conservation standards that address
water heaters with such capabilities, if finalized, because DOE has
determined that this change to the test procedure will impact the
measured efficiency of such water heaters. Under 42 U.S.C. 6293(c)(2),
effective 180 days after an amended or new test procedure is prescribed
or established for a covered product, no regulated party (i.e.,
manufacturer, distributor, retailer, or private labeler) may make any
representations about the energy use or efficiency of such product
unless it has been tested according to the new or amended test
procedure and such representations fairly disclose the results of such
testing. In the present case, DOE is making clear that its test
procedure provisions related to high temperature testing are not
required to be used until the compliance date of any amended standards
that address such water heaters.
Under 42 U.S.C. 6293(e)(1), DOE must determine whether any test
procedure amendments would alter the measured energy efficiency, energy
use, or
[[Page 40451]]
measured water use of any covered products as determined under the
existing test procedure. As explained elsewhere, DOE has determined
that the provisions for high temperature testing would alter measured
efficiency, so this statutory provision is likewise satisfied.
Finally, under 42 U.S.C. 6293(e)(2), if DOE determines that its
amended test procedure will alter the measured energy efficiency or
energy use of a covered product, the Department shall amend the
applicable energy conservation standard during the rulemaking carried
out with respect to such test procedure. This provision applies to the
currently applicable energy conservation standard. As noted previously,
the high temperature testing provisions that would alter the measured
energy efficiency of certain water heaters are not required for
determining compliance with the currently applicable standard. These
provisions would only be required on the compliance date of any amended
standards that address such water heaters. As such, there is no need to
amend the current standards under 42 U.S.C. 6293(e)(2).
DOE has determined that the high temperature test method should
apply to electric resistance storage water heaters for the reasons
discussed in section III.E.1 of this document. Specifically, based on
information from stakeholders regarding the operation of demand-
response water heaters (see section III.E.1.b of this document) and the
Department's own testing and calculations (see section III.F.2.a of
this document), DOE has determined that the high temperature test
method would apply to electric resistance storage water heaters that
are capable of raising their internal tank temperature significantly
above their delivery temperature, without utility initiation, to boost
hot water delivery capacity in order to meet daily household needs.
Products which raise the internal tank temperature only as part of
demand-response operation should not use this method.
In this rulemaking, commenters have urged DOE to provide better
clarity and specificity regarding which water heaters may be ``exempt''
from high temperature testing (for example, see NYSERDA's comments
discussed in section III.A.1 of this document). In the concurrent the
energy conservation standards rulemaking, DOE may consider and propose
additional criteria to further specify the subset of water heaters
which would have to comply with potential amended standards using the
high temperature test method. This is because there could be specific
cases when a water heater would reach a higher storage tank temperature
in a way that does not necessarily increase the delivery capacity over
the course of an average use cycle. For example, a user may choose to
use an elevated setpoint for storage temperature, but with a delivery
temperature equal to this setpoint. In such a case where a higher
delivery temperature is actually desired, because no cold water mixing
is occurring at the outlet, there is no increase in the volume of hot
water that can be provided to the home. Therefore, in its accompanying
energy conservation standards rulemaking for consumer water heaters,
DOE will consider specifying what user-controllable tank temperature
settings might actually constitute ``delivery capacity boosting.''
Additionally, DOE will also consider the length of time these settings
may be in use to determine which types of temperature settings would
result in capacity boosting over an average daily use cycle.
Once again, because high temperature testing may cause ratings for
certain electric resistance storage water heaters to decrease, DOE is
not requiring the use of these test provisions until the compliance
date of any new energy conservation standards addressing such water
heaters (i.e., as part of the separate rulemakings for consumer water
heaters). After the effective date of this final rule and before the
compliance date of an amended standards final rule, manufacturers of
certain electric resistance storage water heaters will be allowed to
use the high temperature test method voluntarily to make additional
representations of performance in high-temperature mode.
2. Very Small Draw Pattern Flow Rate
Section 5.4.1 of appendix E states that if the Max GPM is less than
1.7 gpm (6.4 L/min), then the very small draw pattern must be used
during the 24-hour simulated-use test. Section 5.5 of appendix E states
that, for the very small draw pattern, if the water heater has a Max
GPM rating less than 1 gpm (3.8 L/min), then all draws shall be
implemented at a flow rate equal to the rated Max GPM.
As discussed in the January 2022 NOPR, DOE has identified flow-
activated water heaters that are designed to deliver water at the set
point temperature of 125 [deg]F 5 [deg]F (51.7 [deg]C
2.8 [deg]C) that is required by section 2.5 of appendix E
at a flow rate well below 1 gpm (3.8 L/min). For these products, the
second draw of the very small draw pattern requires 1 gallon to be
removed at the rated Max GPM, and the pattern requires the third draw
to start five minutes after the initiation of the second draw. However,
any rated Max GPM less than or equal to 0.2 gpm (0.76 L/min) will
result in the second draw lasting more than five minutes and past the
start time of the third draw. To clarify the appropriate method of
testing these products, DOE proposed to amend the very small draw
pattern description to state that when a draw extends beyond the start
time of a subsequent draw, that the subsequent draw will start after
the required volume of the previous draw has been delivered. 87 FR
1554, 1582 (Jan. 11, 2022).
DOE did not receive any comments in response to this proposal, so,
therefore, in this final rule, DOE is adopting the amendment to
appendix E as proposed in the January 2022 NOPR for the reasons
previously stated.
3. Low-Temperature Water Heaters
Low-temperature water heaters (discussed further in section
III.A.4.b of this document) are flow-activated products that do not
deliver temperatures within the required set point temperature range of
125 [deg]F 5 [deg]F when tested according to the supply
water temperature and flow rate requirements of appendix E. These
products are typically suited for point-of-use (POU) applications where
the outlet water is minimally tempered prior to delivery through the
faucet (typically marketed as ``handwashing'' or ``POU water
heaters''). However, because these products cannot meet the outlet
temperature requirements in appendix E, DOE is establishing new
provisions to address these products.
One primary concern identified in this rulemaking is that these
units typically have low heating rates, which currently requires the
testing agency to reduce the flow rate in order to be able to achieve
the outlet temperature within the set point temperature range. However,
these units have a minimum activation flow rate below which the unit
shuts off. To the extent that a unit would stop heating water when the
flow rate is too low, there may be no flow rate at which the unit would
operate and deliver water at the outlet temperature required under
section 2.5 of appendix E. In response to the April 2020 RFI,
commenters generally indicated that DOE should adopt provisions to use
a lower setpoint temperature for low-temperature water heaters. 87 FR
1554, 1582 (Jan. 11, 2022).
For the reasons explained in further detail in the January 2022
NOPR, DOE proposed that low-temperature water heaters be tested at the
maximum delivery temperature when using the flow rate requirements
already
[[Page 40452]]
established in appendix E. Specifically, lowering the flow rate in
order to establish a delivery temperature of 125 [deg]F may not be
feasible for these products because the flow rate may be so low that
the water heater does not activate. DOE tentatively determined that
lowering the set point temperature for low-temperature water heaters to
their maximum possible delivery temperature would permit these water
heaters to be tested appropriately and in a manner that would produce
representative test results. 87 FR 1554, 1582-1583 (Jan. 11, 2022).
In commenting on this issue, BWC requested that DOE further assess
differences in testing and ratings between electric instantaneous water
heaters and low-temperature water heaters. (BWC, No. 33 at p. 8)
In response, DOE will continue to assess the impact of the test
procedure provision in section 5.2.2 of appendix E on ratings for low-
temperature water heaters as more of these products enter the market
and are certified, but at this time, DOE is adopting these provisions
in order to set forth a repeatable, representative approach to testing
such products. Currently, there is no appendix E test method to test
low-temperature water heaters, and, therefore, ratings for low-
temperature water heaters are not possible until the effective date of
this final rule. DOE is distinguishing low-temperature water heaters
from other electric instantaneous water heaters mainly on the inability
to reach the standardized outlet water temperatures under the appendix
E test procedure. DOE will consider potential impacts on UEF ratings in
its concurrent energy conservation standards rulemaking (see Docket No.
EERE-2017-BT-STD-0019).
4. Delivery Temperature for Flow-Activated Water Heaters
In providing comments in response to the January 2022 NOPR, AET
introduced a new topic for DOE to consider when amending the test
procedure for consumer water heaters and residential-duty commercial
water heaters. AET indicated that the test procedure needs to further
clarify the process for setting the delivery temperature for flow-
activated water heaters. The commenter argued that such clarification
is necessary because the DOE test procedure simply says to initiate
normal operation of the water heater at the design power rating. AET
stated that, when operating flow-activated water heaters at their
maximum heating rate, outlet temperature can be controlled two
different ways: (1) adjust some thermostat, and/or (2) adjust flow
rate; since the instructions do not specify a flow rate at which to set
the thermostat, it is theoretically possible to set the thermostat to a
very high temperature, and then adjust the flow rate so that the unit
only delivers the desired 125 [deg]F outlet temperature. AET claimed
that this would allow the water heater to deliver much hotter
temperatures when the flow rate is less than the flow rate needed to
deliver 125 [deg]F when operating at maximum heating rate. AET
recommended to amend the test procedure so as to provide instructions
that the flow rate for draws should be 90 percent of the theoretically
calculated maximum flow rate that could be achieved when operating at a
full heating rate and delivering the required 125 [deg]F outlet
temperature in order to ensure that this temperature is consistent.
(AET, No. 29 at p. 11)
On this issue, DOE notes that section 5.2.2.1 of appendix E,
``Flow-Activated Water Heaters, including certain instantaneous water
heaters and certain storage-type water heaters,'' instructs the test
agency to first initiate normal operation of the water heater at the
full input rating for electric water heaters and at the maximum firing
rate specified by the manufacturer for gas or oil water heaters.
Section 5.2.2.1 then states that the test agency must monitor the
discharge water temperature and set to a value of 125 [deg]F 5 [deg]F (51.7 [deg]C 2.8 [deg]C) in accordance with
the manufacturer's instructions. If the water heater is not capable of
providing this discharge temperature when the flow rate is 1.7 gallons
0.25 gallons per minute (6.4 liters 0.95 liters
per minute), then the flow rate is adjusted as necessary to achieve the
specified discharge water temperature. Once the proper temperature
control setting is achieved, the setting must remain fixed for the
duration of the maximum GPM test and the simulated-use test.
In response to AET's comment, DOE notes that the current appendix E
test instructions specify that the flow rate for setting the discharge
water temperature is 1.7 gallons 0.25 gallons per minute
(6.4 liters 0.95 liters per minute). If a discharge
temperature of 125 [deg]F 5 [deg]F is not possible at that
flow rate, the test method allows for the flow rate to be varied only
to the extent necessary to achieve a discharge temperature of 125
[deg]F 5 [deg]F. Therefore, DOE has determined that the
current instruction is explicit enough for the delivery temperature
setting to be conducted in a repeatable and reproducible manner.
5. Heat Pump Water Heaters
In this rulemaking, DOE has sought to address multiple test
procedure provisions related to heat pump water heaters. In section
III.A.2 of this final rule, DOE discusses the scope of applicability of
the appendix E test procedure to heat pump water heaters designed for
residential applications. Section III.C.7 of this document describes
the new optional test conditions being allowed for heat pump water
heaters for voluntary representations of EX based on NEEA's
Advanced Water Heating Specification. Additionally, DOE is amending
ambient air condition tolerances for heat pump water heater testing
because air-source heat pumps exchange latent and sensible heat \73\
with the surrounding air, and, thus, the water heater's normal
operation will have a tangible impact on air temperature and moisture
content (see section III.C.4 of this document). Furthermore, there are
other requirements being established for the test set-up and
installation of split-system heat pump water heaters and circulating
heat pump water heaters (see sections III.D.1 and III.D.4 of this
document).
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\73\ ``Sensible heat'' refers to heat that is exchanged with
surrounding air that is detectable by measuring the change in
temperature of the air, as it does not change the moisture content
of the air. ``Latent heat'' refers to heat that is exchanged when
moisture in the air is condensed into liquid water (i.e., at the
evaporator of a heat pump water heater).
---------------------------------------------------------------------------
In addition to these topics, DOE has evaluated the draw patterns
for conducting the 24-hour simulated-use test on heat pump water
heaters with back-up electric resistance heating elements. In the
present market, consumer heat pump water heaters are typically
``integrated,'' with the air-source heat pump and storage tank built
together into one assembly. This ``typical'' consumer heat pump water
heater uses electricity and has back-up electric resistance elements
within the storage tank. Heating water with the heat pump components is
more efficient than heating water with the back-up resistance elements.
Therefore, water heaters with controls that prioritize heat pump water
heating over resistance element water heating will operate more
efficiently than water heaters that do not prioritize heat pump water
heating or that do not prioritize heat pump water heating to the same
extent.
In response to the April 2020 RFI, the Joint Commenters suggested
modifying the test procedure to reflect the effectiveness of controls
in minimizing use of the resistance element in heat pump water heaters,
stating this modification would improve the
[[Page 40453]]
representativeness of the test procedure and create new incentives for
manufacturers to develop products that provide increased savings for
consumers. As noted in the January 2022 NOPR, no suggestion was
provided on how to better reflect the use of controls to minimize
element usage. 87 FR 1554, 1583 (Jan. 11, 2022).
In the January 2022 NOPR, DOE noted that its test data indicate
that most (or possibly all) heat pump water heater models available on
the market currently operate without activating the electric elements
during the 24-hour simulated-use test under the current appendix E test
procedure. DOE argued that although element usage during the test could
be forced through a more aggressive draw pattern (i.e., longer or more
frequent draws designed to deplete the water heater and require more
hot water than the heat pump alone could keep up with), the draw
patterns are required to be representative of actual use. Therefore,
designing the draw pattern with the goal of forcing resistance element
use would not be representative of typical use. 87 FR 1554, 1583 (Jan.
11, 2022).
In commenting on this issue in response to the January 2022 NOPR,
the ASAP, ACEEE and NCLC once again encouraged DOE to evaluate whether
current draw patterns are representative of real-world conditions for
heat pump water heaters. The ASAP, ACEEE and NCLC noted that
investigations conducted by NEEA \74\ indicate that electric resistance
elements are activated more frequently in heat pump water heaters than
DOE observed in its testing. Specifically, ASAP, ACEEE and NCLC pointed
to the finding in the NEEA study that the average annual proportion of
total input energy that was provided by resistance heat ranged from 4
to 45 percent, depending on the water heater model and location of
installation. (ASAP, ACEEE, and NCLC, No. 34 at p. 2) However, DOE did
not receive any additional comments in this rulemaking providing any
specific approach to testing heat pump water heaters with back-up
electric resistance elements in a more representative manner.
---------------------------------------------------------------------------
\74\ ASAP, ACEEE and NCLC cited NEEA's 2015 Heat Pump Water
Heater Model Validation Study, (Report #E15-306), found online at:
ecotopewebstorage.s3.amazonaws.com/2015_001_1_HPWHModelVal.pdf (Last
accessed on Sept. 13, 2022).
---------------------------------------------------------------------------
In response, DOE notes that the 2015 study by NEEA relies on data
collected in a limited geographical area within the U.S.--namely, the
Pacific Northwest--and the results may not be representative of
installations across the U.S, which is the requisite benchmark for a
Federal test procedure. For example, one condition for electric
resistance back-up is when the ambient air temperature is below the
low-temperature cut-out of the compressor (e.g., 45 [deg]F), and this
is more likely to occur in northern climates than it is to occur across
the country as a whole. Nevertheless, the study finding demonstrated a
substantial range of electric resistance contribution, such that it
remains unclear whether an amended draw pattern would be more
representative.
The CA IOUs did, however, suggest that DOE should consider any
distinguishing characteristics of 120-volt heat pump water heaters that
might require changes to the test procedure to represent their real-
world performance accurately. (CA IOUs, No. 36 at p. 4) In response to
the CA IOUs, within the context of back-up element usage, early
indications suggest that not all 120-volt heat pump water heaters will
employ back-up electric resistance heating elements due to limitations
on a 120-volt circuit, but this market is still evolving. As of this
final rule, there are only a limited number of commercially-available
120-volt heat pump water heaters, so DOE has determined that it is
premature to establish specific testing requirements for 120-volt heat
pump water heaters at this time. Without adequate test data from these
products, there is uncertainty as to what, if any, specific
requirements for 120-volt heat pump water heaters would be appropriate.
Therefore, after considering these comments and the lack of
available data on this topic, DOE has decided to maintain the current
language in section 5.1 of appendix E and is not adopting draw patterns
specific to any type of heat pump water heater. Accordingly, the draw
patterns for electric water heaters generally will continue to apply to
these products. DOE will continue to collect information on this topic
to inform a future test procedure rulemaking.
6. Draw Pattern for Commercial Applications
In response to the April 2020 RFI and as discussed in the January
2022 NOPR, EEI suggested DOE consider a test procedure for consumer
water heaters used in commercial applications that includes a draw
pattern more demanding than the ``high'' draw pattern, which is
currently the draw pattern with the largest amount of delivered water
in the appendix E test procedure. 87 FR 1554, 1575-1576 (Jan. 11,
2022).
In the January 2022 NOPR, DOE stated that 42 U.S.C. 6293(b)(3), in
relevant part, requires that any test procedures prescribed or amended
shall be reasonably designed to produce test results which measure
energy efficiency of a covered product during a representative average
use cycle or period of use. Consumer water heaters are designed for use
in residential applications, and as such, a draw pattern representative
of a commercial installation would not be representative of the
product's average use cycle or period of use. For these reasons, DOE
declined to propose a draw pattern with a delivered volume greater than
the high draw pattern in appendix E. 87 FR 1554, 1576 (Jan. 11, 2022).
BWC agreed that there is no need for a draw pattern above ``high
draw,'' since the high draw pattern adequately addresses products that
have high hot water deliverability within the scope of the test
procedure. (BWC, No. 33 at p. 6)
As such, DOE is not adding another draw pattern to the appendix E
test procedure in this final rule for the reasons previously stated.
7. Method for Determining Internal Tank Temperature for Certain Water
Heaters
Section 4.5 of appendix E provides the procedure for measuring the
internal storage tank temperature for water heaters with a rated
storage volume at or above 2 gallons. Section 4.5 of appendix E
specifies that the thermocouples be inserted into the storage tank of a
water heater through either the anodic device opening, the temperature
and pressure relief valve, or the outlet water line. However, DOE has
identified consumer water heaters with physical attributes that make
measuring internal storage tank temperature difficult, such as water
heaters that have a built-in mixing valve and no anodic device, or that
have a large heat exchanger that does not accommodate insertion of a
thermocouple tree. In this rulemaking, DOE sought suggestions from
stakeholders on how the internal storage tank temperature should be
measured for these types of designs. After considering the comments
received, DOE is amending the appendix E test procedure to specify a
method for determining the internal mean tank temperature for such
products, as discussed in detail later in this section.
In response to the April 2020 RFI and as discussed in the January
2022 NOPR, BWC recommended a ``drain-down'' approach to address water
heaters that cannot have their internal storage tank
[[Page 40454]]
temperatures measured directly (a position echoed by Rheem). More
specifically, BWC's suggested approach consisted of the following: (1)
After the FHR test, purging the water heater with inlet water at 58
[deg]F 2 [deg]F to establish the mean tank temperature at
the beginning of the 24-hour simulated-use test; (2) allowing the water
heater to heat up to the original thermostat setting and recording the
energy used to do so; (3) running the appropriate draw pattern, then
fully draining the water heater by gravity, while measuring the mass
and temperature of the water; and (4) calculating the energy change as:
energy change = mass x specific heat x the difference between the
average end temperature and the beginning temperature just after the 58
[deg]F purge. Rheem also supported a drain-down method, whereby the
entire volume would be removed and the temperature measured at the end
of the 24-hour test. 87 FR 1554, 1586 (Jan. 11, 2022).
However, DOE's primary concern with the suggested drain-down
approach was that it cannot be conducted at every stage during the 24-
hour simulated-use test when the mean tank temperature measurement is
required. As discussed in the January 2022 NOPR, the procedures
recommended by BWC and Rheem could provide an estimate of the mean tank
temperature at the start and end of the 24-hour simulated-use test but
would not provide an estimate at the end of the first recovery period,
the start and end of the standby period, or an average over the standby
period, all of which are required for determining UEF. Instead of BWC's
drain-down approach, DOE initially proposed a methodology with a
modified approach, wherein the mean tank temperature would be estimated
as the average of the inlet water temperature and the outlet water
temperature each time a mean tank temperature measurement was required.
This method assumes that the stored water gradually (i.e., linearly)
increases in temperature either from the bottom of the tank to the top,
or the further the water is into the heat exchanger from the water
inlet, depending on the design of the water heater being tested. As the
exact internal dimensions of the storage tank or heat exchanger cannot
be known for every water heater, DOE reasoned that the linear
assumption is the most representative of the water heater market as a
whole. 87 FR 1554, 1586-1587 (Jan. 11, 2022).
In response to DOE's proposal, AHRI, A.O. Smith, and BWC indicated
that the linear temperature gradient assumption inherent to the
proposed methodology in the January 2022 NOPR is incorrect, based on
the companies' own test results. (AHRI, No. 40 at p. 5; A.O. Smith, No.
37 at pp. 5-6; BWC, No. 33 at p. 10) In contrast, Rheem supported DOE's
proposed linear temperature gradient assumption. (Rheem, No. 31 at p.
4) None of the comments received in response to the January 2022 NOPR
suggested an alternative approach, so in the July 2022 SNOPR, DOE
revised its proposal to incorporate aspects of BWC's method but
included additional methods to estimate the intermediate temperatures
required for efficiency calculations. 87 FR 42270, 42283-42284 (July
14, 2022).
In the July 2022 SNOPR, DOE proposed the following methodology for
water heaters with rated storage volumes greater than or equal to 2
gallons that are unable to have their internal tank temperatures
measured using thermocouples:
(1) After the FHR test (for non-flow-activated products) or Max GPM
test (for flow-activated products), allow the water heater to fully
recover.
(2) When cut-out occurs, deactivate the burner, compressor, and/or
electrical heating elements.
(3) Remove the hot water from the tank by performing a continuous
draw, while measuring the outlet water temperature at 3-second
intervals, until the outlet water temperature is within 2 [deg]F of the
inlet water temperature for five consecutive readings. Perform the draw
at a flow rate of 3.0 gallons per minute (0.25 gallons per
minute). Compute the mean tank temperature, Tst, as follows and assign
this value as T0, Tsu,0, and Tmax,1:
[GRAPHIC] [TIFF OMITTED] TR21JN23.005
Where:
Tst = the estimated average internal storage tank
temperature.
Tp = the average of the inlet and the outlet water
temperatures at the end of the period defined by [tau]p.
vout,p = the average flow rate during the period.
Vst = the rated storage volume of the water heater.
[tau]p = the duration of the period, determined by
the length of time taken for the outlet water temperature to be
within 2 [deg]F of the inlet water temperature for 15 consecutive
seconds. The duration of the period shall include the 15-second
stabilization period.
Tin,p = the average of the inlet water temperatures
during the period.
Tout,p = the average of the outlet water temperatures
during the period.
(4) Re-activate the burner, compressor, and/or electrical elements
and perform the 24-hour simulated use test as instructed in section 5.4
of appendix E.
(5) The standby period will start at five minutes after the end of
the first recovery period after the last draw of the simulated-use
test. The standby period shall last eight hours, so testing will extend
beyond the 24-hour duration of the simulated-use test. At the end of
the final standby measurement, remove water from the tank once again as
in step #3, including computing the value of mean tank temperature.
This calculated mean tank temperature is then assigned as Tsu,f and
T24.
(6) Determine Tt,stby,1 as the average of Tsu,0 and Tsu,f.
The revised proposal relied on a different assumption--supported by
DOE's test data--that, for typical storage-type water heaters,
T0, Tsu,0, and Tmax,1 are similar in
that they represent temperatures near the cut-out control temperature.
Furthermore, the mean tank temperature at the end of the standby
period, Tsu,f, can also be measured by removing water and
measuring its temperature at the end of a sufficiently long standby
period at the end of the test, and this value could also approximate
T24. 87 FR 42270, 42284-42285 (July 14, 2022).
In response to the July 2022 SNOPR, AHRI stated that manufacturers
would need additional time to complete testing to verify the proposed
equations and requested that DOE provide additional data and evidence
that the method is appropriate before adopting it. Further, AHRI asked
that DOE specify the correct procedure if the initial recovery period
extends beyond the start of the second draw. (AHRI, No. 55 at p. 8)
A.O. Smith expressed support for the revised proposal in the SNOPR, but
the commenter added that manufacturers will need to work with the
Department as additional testing on the identified products ensues,
should this proposed change become part of any final rule.
[[Page 40455]]
(A.O. Smith, No. 51 at p. 9) BWC stated that the equation presented in
the SNOPR is an improvement over the January 2022 NOPR proposal that
will more effectively measure internal tank temperatures. However, BWC
also commented that it has insufficient data to support or reject some
elements of the proposal, and the company provided as an example the
DOE's assumption made in the SNOPR proposal that Tmax and
Tsu are similar. BWC explained that it would like to conduct
additional testing before commenting further. (BWC, No. 48 at p. 5)
Rheem noted that the procedure as proposed in section 5.4.2.2 of
the proposed appendix E does not align with steps 1 and 2 of the
preamble. Specifically, Rheem argued that the preamble states that
after the FHR or Max GPM test, the unit should be allowed to fully
recover, and then, one would deactivate the burner, compressor, and/or
elements, and remove the hot water from the tank, which would result in
a comparatively ``hot'' water temperature that is representative of a
Tmax,1 or Tsu,0 value, both of which are measured
after a draw and that is normally followed by a recovery; however,
section 5.4.2.2 of the proposed appendix E states that a 1-hour idle
period is to be performed prior to draining the tank, which would
result in a comparatively ``low'' water temperature that is
representative of T0, a measurement taken after an idle
period where no energy was added to the tank. Rheem requested DOE
clarify which method should be used. (Rheem, No. 47 at p. 8) Rheem also
requested DOE clarify when a soak-in period is required when testing a
water heater that cannot have the internal storage tank temperature
directly measured, and specifically, the commenter asked whether a
soak-in period is required between draining the tank after FHR testing
and starting the 24-hour simulated use portion of the test. (Rheem, No.
47 at p. 8)
Rheem stated that the proposed procedure drains water from the unit
at a flow rate of 3 gpm until the inlet and outlet temperatures match,
which means all energy in the water and tank/heat exchanger has been
removed from the unit under test. Rheem requested that DOE clarify that
this is the intent of the procedure and suggested that as an
alternative, since the storage volume is known, the test could simply
remove the stored water and estimate the internal tank temperature
using the proposed equation. (Rheem, No. 47 at p. 8) Rheem also
recommended that the flow rate used for draining the tank be the flow
rate of draw 1 of the 24-hour simulated-use test and that the
temperatures be measured throughout the draw, not just after the first
15 seconds, stating that the flow rate of 3 gpm may be too fast for
some water heaters or would not account for the true energy content of
the internal water. (Rheem, No. 47 at p. 8) Lastly, Rheem requested
that DOE provide the derivation of the Tst equation, stating
that the derivation and assumptions are not immediately apparent.
(Rheem, No. 47 at, p. 9)
In response, DOE provides the following clarifications. With
respect to AHRI's request for clarification of the test procedure in
terms of whether the initial recovery period extends beyond the start
of the second draw, DOE notes that the tank would only be drained of
hot water twice regardless of when the initial recovery period ends--
once after recovery after the FHR or max GPM test, and once at the end
of the standby period at the end of the test. The mean tank temperature
determined during the first draining would be used to approximate
Tmax,1 regardless of when that actually occurs during the
test, as DOE expects that Tmax,1, which occurs after the
first recovery period ends, would not vary significantly depending on
whether it occurs after the second draw. Regarding Rheem's request for
a clarification of whether a 1-hour idle period is required before the
first time drawing off all of the hot water in the tank, DOE clarifies
that the 1-hour idle period is required, as was presented in the
regulatory text in the SNOPR. As shown in Table III.3 which follows,
T0 measurements taken after the 1-hour idle period are
comparable to Tmax,1 and Tsu,f measurements. In
addition, for tanks for which the internal tank temperature cannot be
directly measured, the same soak-in provisions apply as those that
apply generally as described in sections 5.2.4 and 5.4.2 of appendix E.
Regarding Rheem's suggestion to remove volume of stored water in
the tank and use the average temperature of that water to represent the
measured mean tank temperature, DOE notes that when drawing off hot
water through the hot water outlet, cold water is introduced into the
tank which could mix with the stored water. Removing only the stored
volume in the tank could result in an artificially low mean tank
temperature due to the cold inlet water mixing with the stored water,
whereas the proposed approach accounts for all of the thermal energy
contained in the tank to estimate the temperature of the stored water
prior to removing the hot water from the tank. A valid estimate of the
tank temperature could be obtained by shutting off the supply (inlet)
water line and draining the tank by gravity using the drain at the
bottom. However, such an approach would likely require additional
equipment for the test set-up, such as an additional temperature
sensor, a flowmeter to measure the water leaving through the drain, and
a flow control valve to manage the water exiting the drain, equipment
not currently included in the typical test set-up. In addition, DOE has
found that for some water heaters, even after draining by gravity, a
small volume of water remains in the bottom of the tank, which would be
difficult to account for under such an approach. After considering
these comments, DOE has concluded that the methodology proposed in the
SNOPR would not require changes to the test set-up and, therefore,
would be less burdensome.
DOE agrees with Rheem that a flow rate of 3.0 gpm may not be
appropriate for all water heaters, and in particular it may be too high
for temperature sampling rates to accurately estimate the mean tank
temperature of smaller water heaters. Thus, DOE is adopting Rheem's
suggestion to withdraw water at a flow rate equal to the flow rate of
the first draw in the applicable draw pattern. DOE also agrees with
Rheem that starting the measurements immediately, rather than after 15
seconds, would provide a more accurate representation of tank
temperature, and, therefore, the Department is adopting that
recommendation as well.
In response to these comments, DOE re-evaluated its own test data
in order to further validate the method for determining internal tank
temperature outlined above. Underpinning this method is an assumption
that during a simulated use test, the mean tank temperatures that occur
after the tank has been in standby for some time, Tsu,f and
T24, are typically very similar to each other, and that the
tank temperatures measured soon after a recovery and subsequent ``cut-
out'', Tsu,0, T0, and Tmax,1, are also
typically very similar to each other. This is because water heaters
with thermostats have a control band near the setpoint which directs
the cut-in and cut-out to occur once the setpoint is reached. Table
III.2 and Table III.3 below show the mean tank temperatures for a
sample of 29 consumer water heaters.
[[Page 40456]]
Table III.2--Tsu,f and T24 Values for Water Heaters Tested by DOE
--------------------------------------------------------------------------------------------------------------------------------------------------------
Difference
between Tsu,f
Tsu,f T24 ([deg]F) and T24
Test No. Product type * Draw pattern ([deg]F) ([deg]F)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1....................................... ES Low....................... 125.2 127.9 2.72
2....................................... ES Medium.................... 121.2 116.7 4.50
3....................................... ES Medium.................... 124.2 123.8 0.40
4....................................... ES Medium.................... 122.7 122.1 0.56
5....................................... ES Medium.................... 120.2 121.6 1.44
6....................................... ES Medium.................... 123.7 120.7 3.04
7....................................... ES Medium.................... 120.1 119.5 0.60
8....................................... ES Low....................... 121.7 122.5 0.78
9....................................... ES Medium.................... 124.2 117.8 6.42
10...................................... ES Medium.................... 127.1 126.8 0.27
11...................................... ES High...................... 124.4 122.9 1.54
12...................................... ES Low....................... 123.4 120.6 2.83
13...................................... ES Medium.................... 121.1 116.0 5.13
14...................................... ES Medium.................... 121.5 119.5 1.96
15...................................... ES Medium.................... 117.4 119.8 2.42
16...................................... ES Medium.................... 117.5 123.9 6.43
17...................................... ES Medium.................... 125.1 124.2 0.93
18...................................... ES Low....................... 121.3 120.4 0.91
19...................................... ES Medium.................... 119.5 119.4 0.10
20...................................... ES Medium.................... 122.7 114.5 8.17
21...................................... ES Medium.................... 116.3 124.5 8.16
22...................................... ES Medium.................... 112.8 118.2 5.38
23...................................... ES Medium.................... 126.0 135.8 9.83
24...................................... ES Medium.................... 124.9 122.7 2.22
25...................................... ES Low....................... 124.1 122.4 1.72
26...................................... GS Medium.................... 125.7 126.3 0.60
27...................................... GS High...................... 125.7 126.3 0.60
28...................................... GS Medium.................... 125.4 132.8 7.40
29...................................... GS High...................... 128.9 130.6 1.70
-----------------------------------------------
Minimum............................. .................................. .......................... .............. .............. 0.10
Arithmetic Mean..................... .................................. .......................... .............. .............. 3.06
Maximum............................. .................................. .......................... .............. .............. 9.83
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Note: ``ES'' denotes an electric storage water heater, and ``GS'' denotes a gas-fired storage water heater.
Table III.3--T0, Tmax,1, and Tsu,0 Values for Water Heaters Tested by DOE
--------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum
difference
between T0
T0 ([deg]F) Tmax,1 Tsu,0 Tmax,1 and
Test No. Product type * Draw pattern ([deg]F) ([deg]F) Tsu,0
([deg]F)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1................................. ES Low.................. 118.2 116.8 114.0 4.20
2................................. ES Medium............... 117.1 119.8 120.2 3.07
3................................. ES Medium............... 119.0 116.0 119.6 3.60
4................................. ES Medium............... 118.3 119.6 120.2 1.95
5................................. ES Medium............... 124.2 117.8 119.5 6.36
6................................. ES Medium............... 117.7 118.7 119.8 2.13
7................................. ES Medium............... 119.2 116.2 117.5 3.02
8................................. ES Low.................. 122.0 117.1 115.6 6.40
9................................. ES Medium............... 124.4 121.3 121.1 3.33
10................................ ES Medium............... 122.4 120.5 122.5 2.00
11................................ ES High................. 120.8 121.1 122.7 1.91
12................................ ES Low.................. 123.8 120.7 124.5 3.80
13................................ ES Medium............... 116.8 121.9 119.5 5.13
14................................ ES Medium............... 120.8 126.0 125.2 5.17
15................................ ES Medium............... 121.8 121.2 121.6 0.56
16................................ ES Medium............... 120.6 121.8 122.6 1.98
17................................ ES Medium............... 121.1 118.6 121.4 2.80
18................................ ES Low.................. 121.0 121.4 118.6 2.80
19................................ ES Medium............... 122.5 115.3 116.5 7.20
20................................ ES Medium............... 120.1 124.1 125.8 5.75
21................................ ES Medium............... 124.5 116.7 118.8 7.80
22................................ ES Medium............... 122.7 113.6 114.9 9.05
23................................ ES Medium............... 125.6 120.4 122.2 5.23
24................................ ES Medium............... 124.6 124.4 125.4 1.00
25................................ ES Low.................. 123.4 118.4 119.1 4.97
[[Page 40457]]
26................................ GS Medium............... 125.0 126.0 128.0 3.00
27................................ GS High................. 126.1 125.2 131.8 6.60
28................................ GS Medium............... 124.1 128.7 131.4 7.30
29................................ GS High................. 124.7 123.8 129.8 6.00
---------------------------------------------------------------
Minimum....................... ............................. ..................... .............. .............. .............. 0.5656
Arithmetic Mean............... ............................. ..................... .............. .............. .............. 4.28
Maximum....................... ............................. ..................... .............. .............. .............. 9.05
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Note: ``ES'' denotes an electric storage water heater, and ``GS'' denotes a gas-fired storage water heater.
On average, across multiple product classes, the temperatures
Tsu,f and T24 vary about 3 [deg]F from each
other. Similarly, the temperatures T0, Tmax,1,
and Tsu,0 vary about 4 [deg]F from for each other. In both
cases, the range of variability between the mean tank temperatures of
the water heaters in the sample was from less than 1 [deg]F up to 9
[deg]F. Based on these data, DOE has concluded that both the
temperatures are similar enough among each other that grouping them
together for determining internal storage tank temperature, as proposed
in the July 2022 SNOPR, is reasonably valid when there is no direct
alternative of measuring these temperatures. As such, in this final
rule, DOE is adopting the method for determining internal storage tank
temperature as proposed in the July 2022 SNOPR with the modifications
discussed in the preceding paragraphs.
In response to Rheem's request for a derivation of the
Tst equation, DOE notes that it was derived based on the
assumption that the withdrawn water has the same amount of energy as
the water stored in the tank, since there would be no energy input
(i.e., the burner, compressor, and/or electrical heating elements are
deactivated) and assuming minimal losses over the course of the draw.
Specifically, DOE sought to determine the initial mean tank temperature
of the water, denoted by Tst. The energy in the withdrawn
water can be calculated based on its mass, specific heat, and the
temperature difference between the water and the ambient air, which are
all parameters that can be measured or determined directly as the water
is being withdrawn from the tank. As noted previously, this value can
then be assumed to be equal to the energy that would have been stored
in the tank before withdrawing the water, which can also be determined
based on its mass, specific heat, and temperature difference. The mass
of water in the tank can be determined based on the stored volume and
density; the specific heat can be assumed as 1 Btu/lb[deg]F, and the
temperature difference can be calculated as Tst. minus the
ambient temperature. As Tst is the only unknown, the
equation can be rearranged to solve for Tst to provide an
estimate of the mean tank temperature prior to withdrawing water.
In response to requests made by AHRI, A.O. Smith, and BWC for
additional time to conduct testing, DOE reiterates that test procedures
must be established for all products within the scope of this
rulemaking. DOE is finalizing this method for determining internal tank
temperature based on an evaluation of its own test data, and the
Department does not believe it is necessary to delay publication of
this final rule for additional data to be collected on this topic.
Water heaters with rated storage volumes greater than or equal to 2
gallons whose internal tank temperatures cannot be measured using
thermocouples meet the definition of ``consumer water heater'' as
codified at 10 CFR 430.2; therefore, they are covered products and must
have applicable test procedures. In this case, based on information
from its own testing, DOE is establishing these test procedures in this
final rule.
8. Alternate Order 24-Hour Simulated-Use Test
As discussed in the January 2022 NOPR, DOE received comments at the
RFI stage from SMTI recommending that DOE move the standby loss period
of the test to the beginning of the 24-hour simulated-use test and to
start the first draw at the 6-hour mark, based on claims that water
heaters with large storage volumes but low input rates (e.g., storage-
type heat pump water heaters) may receive artificially low recovery
efficiency results from the current test method with the standby loss
period occurring in the middle of the test. 87 FR 1554, 1587 (Jan. 11,
2022).
In the January 2022 NOPR, DOE noted that as a general matter, the
result of the standby period has a negligible effect on UEF, so moving
the standby period to the start of the rest would likewise have a
negligible effect on UEF in terms of improving the accuracy of the
standby loss calculations for most water heaters. However, DOE agreed
that moving the standby period to the start of the test may affect the
recovery efficiency of the large-volume/low-input-rate water heaters
described by SMTI, and a large change in recovery efficiency can have a
significant effect on UEF. DOE tentatively determined that the first
recovery is rarely delayed past the first draw (based on DOE's own test
data), but if the order of the 24-hour simulated-use test were to be
changed (i.e., placing the standby loss period at the beginning), all
water heaters on the market would need to be retested. Therefore, DOE
declined to propose such a change, as the associated burden on
manufacturers to retest would result in a potential increase in
accuracy for only a small subset of the consumer water heaters
available on the market. 87 FR 1554, 1587 (Jan. 11, 2022).
DOE did not receive further comments on this topic. Therefore, DOE
has decided not to move the standby period to the start of the 24-hour
simulated-use test because such amendment would be unduly burdensome on
all manufacturers, as they would be required to retest all of their
products, even though the representativeness of the efficiency results
would be improved for only a small subset of water heaters.
F. Computations
1. Mass Calculations
In sections 6.3.5 and 6.4.2 of appendix E, the mass withdrawn
during
[[Page 40458]]
each draw (Mi) is used to calculate the daily energy
consumption of the heated water at the measured average temperature
rise across the water heater (QHW). However, neither section
includes a description of how to calculate the mass withdrawn for tests
in which the mass is indirectly determined using density and volume
measurements. In the April 2020 RFI, DOE requested feedback on whether
to update the consumer water heater test procedure to include a
description of how to calculate the mass withdrawn from each draw in
cases where mass is indirectly determined using density and volume
measurements. 85 FR 21104, 21113 (April 16, 2020). Stakeholders
generally supported including an equation in the computations of
appendix E, with many suggesting that DOE adopt the calculations in the
AHRI Operations Manual for Residential Water Heater Certification
Program. 87 FR 1554, 1582 (Jan. 11, 2022).
In the January 2022 NOPR, DOE proposed that the volume at the
outlet would be multiplied by the density, which would be based on the
average outlet temperature measured during the draw. DOE also proposed
to add procedures similar to those in the AHRI Operations Manual for
Residential Water Heater Certification Program; in particular, DOE
proposed to add a method of converting inlet water volume to outlet
water volume using the ratio of the water densities at the inlet and
outlet.\75\ Id.
---------------------------------------------------------------------------
\75\ The AHRI Operations Manual for Residential Water Heater
Certification Program specifies that the outlet water volume is
equal to the inlet water volume times the inlet water density
divided by the outlet water density.
---------------------------------------------------------------------------
In response to the January 2022 NOPR, BWC supported DOE's proposed
clarifications for calculating water mass from indirect measurements.
(BWC, No. 33 at p. 8)
After carefully considering the comments, in this final rule, DOE
is adopting the computations for determining water mass from indirect
measurements that were proposed in the January 2022 NOPR for the
reasons previously discussed.
2. Effective Storage Volume
In this final rule, DOE is establishing provisions to calculate the
effective storage volume to account for: (1) water heaters which may
increase storage tank temperature to increase delivery capacity, and
(2) circulating water heaters. As discussed throughout section III.E.1
of this document, raising the temperature of the water stored in the
tank can increase the effective storage capacity of the water heater.
Additionally, circulating water heaters are instantaneous-type water
heaters that operate with a separate stored volume of water such that
the actual amount of hot water that can be provided immediately
(without additional heat input) is related to the volume of water
stored in the circulation pipes or in the separate tank--and not the
rated storage volume of the circulating water heater itself. The
following subsections describe the approach used for each case.
a. Storage Water Heaters With Elevated Stored Water Temperature
In the July 2022 SNOPR, DOE addressed multiple comments regarding
water heaters which boost the tank temperature in order to increase
effective storage volume. (Operation in high heat mode and high
temperature testing are discussed in detail in section III.E.1 of this
final rule.) In particular, DOE noted there are certain consumer
activities, such as filling a bathtub, for which the FHR metric and the
rated storage volume metric alone do not sufficiently describe the
water heater's ability to provide a large amount of hot water
immediately. 87 FR 42270, 42280-42281 (July 14, 2022).
For activities such as filling a bathtub, consumers would benefit
more from knowing the effective storage volume (i.e., the volume of
immediately available hot water) of a water heater, whereas for
activities such as taking a shower, consumers could benefit more from
knowing the FHR (i.e., ability to deliver hot water for an extended
period of time). In particular, FHR represents one full hour of
delivery and does not necessarily describe immediate hot water
availability, as FHR is also impacted by the rate of recovery. In the
past, rated storage volume has served as an indication of the amount of
hot water immediately available. However, given the emergence of new
water heater designs that allow operation in high heat mode, and the
option that has existed to increase the tank temperature and install an
external mixing valve, to provide additional capacity, this is no
longer the case for all water heaters. Hence, in addition to FHR, DOE
tentatively determined in the July 2022 SNOPR that effective storage
volume would be a meaningful performance metric for consumers. Id.
Therefore, in the July 2022 SNOPR, DOE proposed a method to
determine effective storage volume, Veff (expressed in
gallons or liters), at section 6.3.1.1 of appendix E. For water heaters
capable of operating in high heat mode (which DOE proposed be
determined by Tmax,1 being greater than Tdel,2
during the 24-hour simulated use test), DOE proposed to calculate the
effective storage volume based on a volume scaling factor and data
already collected during the appendix E test. Id. at 87 FR 42281.
DOE proposed that the volume scaling factor would be determined as
follows, which is derived by comparing the thermal energy stored by the
water heater when the water is heated to 125 [deg]F to the thermal
energy stored at its maximum tank temperature, using temperature data
collected during the test:
[GRAPHIC] [TIFF OMITTED] TR21JN23.006
Where:
kV is the dimensionless volume scaling factor;
[rho](T) is the density of water evaluated at temperature T;
CP(T) is the heat capacity of water evaluated at
temperature T;
Tmax,1 is the maximum measured mean tank temperature
after the first recovery period of the 24-hour simulated-use test,
and
67.5 [deg]F is the average ambient temperature.
87 FR 42270, 42281 (July 14, 2022).
DOE proposed to determine the effective storage volume by
multiplying the measured storage volume by kV. Id.
In response to DOE's effective storage volume proposal, ASAP,
ACEEE, and NRDC expressed support for DOE's proposal to use effective
storage volume as a metric for water heaters with high heat modes.
(ASAP, ACEEE, and NRDC, No. 54 at pp. 2-3)
AHRI requested that DOE provide additional data and evidence
supporting the proposed equations for calculating effective storage
volume and stated that manufacturers would also need
[[Page 40459]]
additional time to complete testing to verify their accuracy,
representativeness, and repeatability. AHRI requested that DOE specify
the correct procedure to evaluate this metric where the initial
recovery period extends beyond the start of the second draw in this
test. (AHRI, No. 55 at pp. 7-8)
BWC requested that DOE conduct further testing for the method to
determine effective storage volume, stating that manufacturers have not
had enough time to conduct their own testing for this proposal. (BWC,
No. 48 at pp. 3-4)
Rheem suggested that DOE may not have enough information to
incorporate effective storage volume into its energy conservation
standards rulemaking without amending certification criteria because
DOE is not requiring it to be reported. (Rheem, No. 47 at p. 8)
Additionally, Rheem stated that models without ``high heat modes'' may
still meet the conditions to be affected by the effective storage
volume calculation, and the commenter requested that DOE clarify how to
calculate effective storage volume when the first recovery period
extends beyond the second draw, raising the concern that the delivery
temperature can be too low as a result of this condition. (Rheem, No.
47 at p. 7)
In order to address these comments, DOE has re-evaluated its own
test data to further examine the implications of the effective storage
volume calculation as proposed in the July 2022 SNOPR. In particular,
DOE sought to address Rheem's concern that the criteria which triggers
effective storage volume calculation (Tmax,1 >
Tdel,2) may lead more models to be impacted than just those
operating with an elevated tank temperature and the request for
clarification on how to calculate effective storage volume in the
instance that the first recovery period extends beyond the second draw.
Table III.3 lists the anonymized test data DOE evaluated to address the
first of these two concerns. These tests were conducted in accordance
with the currently applicable appendix E test procedure, with a nominal
setpoint temperature of 125 [deg]F and no mixing valve installed.
Table III.3--Tmax,1 and Tdel,2 Values for a Sample of Water Heaters
--------------------------------------------------------------------------------------------------------------------------------------------------------
Tmax,1-Tdel,2
Test No. Product type * Draw pattern Tmax,1 Tdel,2 ([deg]F) ** kv > 1 [dagger]
([deg]F) ([deg]F)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1................................. ES Medium.............. 116.0 124.6 -8.6 NO.
2................................. ES Medium.............. 117.8 125.8 -8.0 NO.
3................................. ES Medium.............. 121.3 122.8 -1.5 NO.
4................................. ES Medium.............. 120.4 122.6 -2.2 NO.
5................................. GS Medium.............. 126.0 128.5 -2.5 NO.
6................................. GS High................ 125.2 127.2 -2.0 NO.
7................................. GS Medium.............. 128.7 129.5 -0.8 NO.
8................................. GS High................ 123.8 127.0 -3.2 NO.
Minimum....................... ............................. .................... 116.0 .............. -8.6
Mean.......................... ............................. .................... 122.4 .............. -3.6
Maximum....................... ............................. .................... 128.7 .............. -0.8
Std. Dev...................... ............................. .................... 4.3 .............. 3.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Note: ``ES'' denotes an electric storage water heater, and ``GS'' denotes a gas-fired storage water heater.
** A value of +5 [deg]F or more in this column would satisfy one of the two criteria for determining kV to be greater than 1.
[dagger] Per the effective storage volume calculation provisions established in this final rule.
Upon further evaluation of the test data presented in Table III.3
and based on comments received, in this final rule, DOE is modifying
the approach in its earlier proposal to ensure that kV
values greater than 1 are only calculated for water heaters operating
with a significantly elevated tank temperature--as determined by both
the difference between the storage tank temperature and the delivery
temperature, as well as the storage tank temperature itself.
Specifically, due to the fact that for some of the water heaters in
Table III.3 Tmax,1 is only slightly less than
Tdel,2, DOE has amended the criteria for determining
kV such that a water heater must have both Tmax,1
> 130 [deg]F and Tmax,1 > Tdel,2 + 5 [deg]F in
order to have a kV factor greater than 1. If these two
criteria are not met, then the water heater will be assigned a
kV factor of 1 and will have an effective storage volume
equal to its rated storage volume. This update to DOE's proposed
approach will ensure that effective storage volume is only calculated
to be greater than the rated storage volume for water heaters operating
with a mean tank temperature that is both significantly above 125
[deg]F and significantly above the delivered water temperature. The
data show that for tests conducted at a nominal 125 [deg]F tank
temperature setpoint, a kV greater than 1.0 is not expected.
For additional reference, DOE conducted one test on a water heater set
to its maximum storage tank temperature, resulting in a
Tmax,1 of 159.6 [deg]F and a Tdel,2 of 124.3
[deg]F, which would cause the kV to be equal to 1.59.
Additionally, in order to address Rheem's concern about models for
which the first recovery period extends beyond the start of the second
draw, DOE has examined its own test data for water heaters exhibiting
this behavior. Table III.4 lists anonymized data from 21 tests for
which the first recovery period extended beyond the start of the second
draw. Similar to the previous dataset, these tests were conducted at a
tank temperature setpoint of 125 [deg]F and no mixing valve installed.
DOE agrees that it would not be appropriate to base the effective
storage volume calculation criteria on Tdel,2 if the tank is
still recovering during the second draw, because Tdel,2 may
be lower than it would be had the tank fully recovered. Therefore, for
such cases, DOE has determined that T0 will take the place
of Tmax,1, and Tdel,1 will take the place of
Tdel,2 in the criteria specified previously. DOE has
specified T0 and Tdel,1 as substitutes in this
instance because they are unaffected by the timing of the first
recovery period. Tdel,1 is measured during the first draw of
the test, which will begin prior to the start of a recovery.
T0 is measured immediately before the first draw (during
which Tdel,1 is measured) and before the first recovery
period, and it is, therefore, more representative of internal tank
temperature as a point of comparison with Tdel,1 to
determine whether the storage tank temperature is elevated relative to
the delivery temperature. In reviewing its data for tests whose first
recovery period
[[Page 40460]]
extended into the second draw, as shown in Table III.4, DOE found that
the results using T0 and Tdel,1 are very
comparable to those using Tmax,1 and Tdel,2, as
shown in Table III.3. However, DOE is not making T0 and
Tdel,1 the default variables because when T0 is
paired with Tdel,1, the delta between the two is a slightly
less reliable indicator of when elevated tank temperatures actually
occur, compared to the default pair of Tmax,1 and
Tdel,2. This is evidenced by the fact that the standard
deviation of the delta, T0-Tdel,1, is slightly
higher at 3.6, than that of the default variables, Tmax,1-
Tdel,2, which is 3.0. These standard deviations, along with
other statistics for the test data are shown in Table III.3 and Table
III.4.
Table III.4--T0 and Tdel,1 Values for a Sample of Water Heaters Whose First Recovery Period Extends Into the Second Draw
--------------------------------------------------------------------------------------------------------------------------------------------------------
T0-Tdel,1
Test No. Product type Draw pattern T0 ([deg]F) Tdel,1 ([deg]F) ** kv > 1 [dagger]
([deg]F)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1................................. ES Low................. 118.2 122.8 -4.6 NO.
2................................. ES Medium.............. 117.1 128.7 -11.6 NO.
3................................. ES Medium.............. 118.3 123.7 -5.5 NO.
4................................. ES Medium.............. 117.7 127.7 -10.0 NO.
5................................. ES Medium.............. 119.2 125.9 -6.7 NO.
6................................. ES Low................. 122.0 125.2 -3.2 NO.
7................................. ES Medium.............. 122.4 128.3 -6.0 NO.
8................................. ES High................ 120.8 126.8 -6.0 NO.
9................................. ES Low................. 123.8 125.6 -1.8 NO.
10................................ ES Medium.............. 116.8 129.5 -12.7 NO.
11................................ ES Medium.............. 120.8 123.8 -3.0 NO.
12................................ ES Medium.............. 121.8 123.9 -2.1 NO.
13................................ ES Medium.............. 120.6 123.1 -2.5 NO.
14................................ ES Medium.............. 121.1 126.6 -5.5 NO.
15................................ ES Low................. 121.0 125.0 -4.0 NO.
16................................ ES Medium.............. 122.5 125.3 -2.8 NO.
17................................ ES Medium.............. 120.1 129.0 -9.0 NO.
18................................ ES Medium.............. 124.5 125.0 -0.5 NO.
19................................ ES Medium.............. 122.7 124.3 -1.6 NO.
20................................ ES Medium.............. 124.6 126.3 -1.7 NO.
21................................ ES Low................. 123.4 123.0 0.4 NO.
Minimum....................... ............................. .................... 116.8 .............. -12.7 ...............
Mean.......................... ............................. .................... 120.9 .............. -4.8 ...............
Maximum....................... ............................. .................... 124.6 .............. 0.4 ...............
Std. Dev...................... ............................. .................... 2.4 .............. 3.6 ...............
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Note: ``ES'' denotes an electric storage water heater.
** A value of +5 [deg]F or more in this column would satisfy one of the two criteria for initiating calculation of kV.
[dagger] Per the effective storage volume calculation provisions established in this final rule.
AHRI, A.O. Smith, and Rheem expressed concern that because FHR is
used as a metric for other activities such as building codes, plumbing
codes, and incentive programs, DOE's proposal may cause misalignment
with those requirements, as well as increased burden if manufacturers
were to be required to comply with metrics for both FHR and effective
storage volume. (AHRI, No. 55 at p. 7; A.O. Smith, No. 51 at pp. 7-8;
Rheem, No. 47 at pp. 7-8) Rheem suggested that effective storage volume
is not more appropriate than FHR as a metric of thermal energy storage.
(Rheem, No. 47 at p. 7) A.O. Smith and Rheem also suggested that FHR is
a more meaningful metric for consumers and that effective storage
volume would be confusing. (A.O. Smith, No. 51 at pp. 7-8; Rheem, No.
47 at p. 7)
In response to these comments, the Department confirms that FHR is
not being phased out or fully replaced by effective storage volume in
the DOE test procedure, and, therefore, this additional metric will not
cause misalignment with other programs and regulations based on FHR. As
stated previously, these metrics provide different information:
effective storage volume indicates the amount of hot water that can be
delivered immediately without need for heat input and is correlated to
the standby losses of the tank, whereas the FHR metric is determined by
a test which allows the heat input to remain on and for the water
heater to initiate a recovery. Additionally, manufacturer burden would
be minimal because the effective storage volume can be determined based
on measurements already taken during the 24-hour simulated use test.
DOE notes that in contrast to FHR, effective storage volume is
capable of accounting for the increase in thermal energy associated
with heating water above the intended delivery temperature in
comparison with larger units storing water at conventional
temperatures. It also allows consumers to compare water heaters with
similar delivery capabilities but different sizes, information which
DOE considers meaningful, while avoiding the risk of backsliding for
units with lower-than-normal FHRs, should FHR be used as the metric.
Contrary to what these commenters suggest, DOE finds that providing a
measure of effective storage volume is more likely to prevent consumer
confusion due to the increased transparency it promotes by reflecting
the immediate hot water capacity of the water heater for certain uses
such as filling a bathtub. Combined with the high temperature test
method, consumers would have a way to directly compare the performance
of water heaters of different sizes that can meet the same user needs.
In response to DOE's request for comment regarding its proposed
equations and approach to calculate effective storage volume, Rheem
agreed that DOE's derivation from an energy balance was appropriate for
calculating a scaling factor. (Rheem, No. 47 at p. 7) NEEA commented
that that the
[[Page 40461]]
proposed method appears to contain an error in the calculation of the
dimensionless volume scaling factor (kv,) by using 67.5
[deg]F, the standard test condition ambient air temperature, instead of
58 [deg]F, the standard test condition water inlet temperature.
Otherwise, NEEA indicated support of DOE's proposed method for
calculating the effective storage volume metric. (NEEA, No. 56 at p. 3)
DOE's volume scaling factor is derived by comparing the thermal
energy stored by the water heater when the water is heated to 125
[deg]F to the thermal energy stored at its maximum tank temperature. In
response to NEEA's comment, DOE notes that the method to calculate the
dimensionless volume scaling factor kv uses ambient air
temperature because as the water in the storage tank cools, heat is
lost to the surrounding air. Thus, the water approaches the temperature
of the surrounding air, not the 58 [deg]F inlet water temperature.
Therefore, DOE has maintained this calculation method as originally
proposed.
Rheem suggested that an effective volume scaled to 125 [deg]F is
not useful for customers because a typical bath temperature is around
100 [deg]F. (Rheem, No. 47 at p. 7) In response, DOE notes that the
effective storage volume calculation is to show how much additional
thermal energy is stored in the tank compared to a water heater which
is not raising the internal tank temperature beyond the delivery
temperature. Because 125 [deg]F is the delivery setpoint temperature
used in the appendix E test procedure as being representative of
typical water heater setpoint temperatures, DOE has concluded that it
is appropriate for the tank temperature has to be compared to 125
[deg]F.
The CA IOUs supported DOE's proposed effective storage volume
metric as being more representative of a storage water heater's hot
water delivery capacity than rated storage volume. However, the CA IOUs
asserted that effective storage volume does not account for differences
in recovery rate between water heaters, a factor which also affects hot
water delivery capacity and specifically FHR. The CA IOUs pointed out
that large discrepancies in FHR exist within a given rated storage
volume for both gas and electric storage water heaters. Therefore, the
CA IOUs suggested DOE should revise its proposed algorithm for the
effective storage volume to produce a metric incorporating the volume
and temperature of the stored water and the water heater recovery rate.
(CA IOUs, No. 52 at pp. 2-4)
In response, effective storage volume is intended to measure the
maximum thermal energy a water heater can store and to indicate the
amount of hot water that is immediately available. Effective storage
volume is not intended to measure how fast the unit is able to heat
water. This is in contrast with FHR, which accounts for the water
heater's recovery rate as previously described. Accounting for water
heater recovery rate in the effective storage volume calculation would
make the effective storage volume metric duplicative of the existing
FHR metric; DOE reiterates that effective storage volume will not
replace FHR, which will remain a part of the test procedure. A.O. Smith
stated that the effective storage volume metric may become obsolete if
DOE's proposed energy conservation standards effectively limit the
availability of non-demand response water heaters with user-selectable
high heat modes. (A.O. Smith, No. 51 at p. 7) In response to A.O.
Smith's comment, DOE notes that the scope of this comment falls within
that of the energy conservation standards rulemaking, so it will be
properly considered in the concurrent standards rulemaking for consumer
water heaters. Additionally, DOE would again mention that certification
and representations of effective storage volume will not be required as
a result of this final rule, but instead may be required at the time of
any energy conservation standards that specifically address which water
heaters may be required to carry out high temperature testing.
Finally, when proposing the calculation of estimated mean tank
temperature in the July 2022 SNOPR, DOE inadvertently omitted the
calculation of annual electrical energy consumption from the test
procedure. DOE has once again included this calculation as originally
proposed in the January 2022 NOPR at section 6.3.10 of appendix E.
b. Circulating Water Heaters
As discussed in section III.D.4 of this document, DOE is amending
the test procedure to require that circulating water heaters must be
tested with a separate storage tank. Specifically, gas-fired and oil-
fired circulating water heaters and electric resistance circulating
water heaters must be tested with an UFHWST, and heat pump-type
circulating water heaters must be tested with an electric storage water
heater.
For circulating water heaters, effective storage volume
calculations will be carried out in a slightly different manner than
for storage water heaters. The methodology established in this final
rule takes into consideration the concerns raised by stakeholders and
discussed in section III.D.4 of this document. In summary, while
commenters expressed that it would be beneficial to be able to use a
range of UFHWST volumes for testing non-heat-pump-type circulating
water heaters, commenters were also concerned that the results of
testing may not be reproducible without certifying the specific model
of UFHWST to be used. Regarding the volume, DOE understands that
circulating water heater designs may be optimized to operate with
specific storage volumes; thus, in this final rule, DOE is allowing a
range of volumes to be used. However, manufacturers may represent the
volume of the UFHWST in terms of the effective storage volume of the
circulating water heater as follows.
Because circulating water heaters are to be tested with a separate
storage tank, they operate, as a system, in a similar manner to
storage-type water heaters. Although the volume stored by the
circulating water heater itself may be small, these water heaters
require a separate volume of water to operate properly. Therefore, DOE
has determined that it is appropriate for the effective storage volume
calculation for circulating water heaters to account for the separate
storage tank, as the volume of the stored water is representative of
the effective volume that would be available for such a water heater in
the field, since it is necessary to install a circulating water heater
with a storage tank or other stored volume of water. The procedure for
calculating effective storage volume of separate storage tanks paired
with circulating water heaters is outlined in section 6.3.1.1 of
appendix E. This procedure will prescribe the value of the measured
storage volume of the separate storage tank to be the effective storage
volume of the circulating water heater, and the measured storage volume
of the separate storage tank shall be determined in accordance with
section 5.2.1 of the amended appendix E (Determination of Storage Tank
Volume). This allows the same method of volume measurement to be
applied to UFHWSTs and separate electric resistance storage tanks. DOE
has determined that this approach allows for manufacturers to have the
flexibility to use the appropriate size of UFHWST for the circulating
water heater while still ensuring that testing can be done in a
reproducible manner.
In a separate rulemaking pertaining to certification requirements
for consumer water heaters and residential-duty commercial water
heaters, DOE will address any potential amendments
[[Page 40462]]
which would need to be made in order to certify the effective storage
volume of a product. DOE would consider establishing product-specific
enforcement provisions for circulating water heaters at such a time
when energy conservation standards for these products are evaluated.
G. Untested Provisions (Alternative Efficiency Determination Methods)
At 10 CFR 429.70, DOE specifies alternative methods for determining
energy efficiency and energy use for certain covered products and
equipment, including consumer water heaters.\76\ In general, these
provisions allow a manufacturer to determine the energy efficiency or
energy use of a basic model using an alternative efficiency
determination method (AEDM) in lieu of actually testing the basic
model. Specific to each product or equipment type covered by these AEDM
provisions, DOE defines the criteria for using an AEDM and, for some
products and equipment, procedures to be used to validate an AEDM and
to perform verification testing on units certified using an AEDM.
---------------------------------------------------------------------------
\76\ Section 429.71 uses the term ``residential,'', which is
synonymous with the use of the term ``consumer'' in this document.
---------------------------------------------------------------------------
The provisions at 10 CFR 429.70(g) provide alternative methods for
determining ratings for ``untested'' basic models of residential water
heaters and residential-duty commercial water heaters. For models of
water heaters that differ only in fuel type or power input, these
provisions allow manufacturers to establish ratings for untested basic
models based on the ratings of tested basic models if certain
prescribed requirements are met. (Simulations or other modeling
predictions or ratings of UEF, volume, first-hour rating, or maximum
gallons per minute are not permitted (10 CFR 429.70(g)).)
Specifically, for gas water heaters, the provisions at 10 CFR
429.70(g)(1) specify that for untested basic models of gas-fired water
heaters that differ from tested basic models only in whether the basic
models use natural gas or propane gas, the represented value of UEF,
FHR, and maximum gallons per minute for an untested basic model can be
the same as those for a tested basic model, as long as the input
ratings of the tested and untested basic models are within 10 percent.
For electric storage water heaters, the provisions at 10 CFR
429.70(g)(2) specify rating an untested basic model using the FHR and
the UEF obtained from a tested basic model as a basis for ratings of
basic models with other input ratings, provided that certain conditions
are met: (1) each heating element of the untested basic model is rated
at or above the input rating for the corresponding heating element of
the tested basic model; and (2) for an untested basic model having any
heating element with an input rating that is lower than that of the
corresponding heating element in the tested basic model, the FHR for
the untested basic model must result in the same draw pattern specified
in Table I of appendix E for the simulated-use test as was applied to
the tested basic model.\77\ 10 CFR 429.70(g)(2)(i)-(ii).
---------------------------------------------------------------------------
\77\ To establish whether this condition is met, the provisions
at 10 CFR 429.70(g)(2)(ii) specify determining the FHR for the
tested and the untested basic models in accordance with the
procedure described in section 5.3.3 of 10 CFR part 430, subpart B,
appendix E, and then comparing the appropriate draw pattern
specified in Table I of appendix E for the FHR of the tested basic
model with that for the untested basic model. If this condition is
not met, then the untested basic model must be tested and the
appropriate sampling provisions applied to determine its UEF in
accordance with appendix E.
---------------------------------------------------------------------------
In commenting on this topic in response to the January 2022 NOPR,
Rheem suggested expanding the AEDM provisions for consumer water
heaters to address circulating water heaters. Specifically, Rheem
identified three possible AEDM approaches: (1) test the thermal
efficiency or COP using the commercial water heater test procedure and
use the result to calculate an estimated UEF for various storage
capacities; (2) open the commercial HVAC AEDM provisions at 10 CFR
429.70(c) to circulating consumer water heaters; or (3) add provisions
similar to the current electric storage water heater AEDM, where a
change in draw pattern would necessitate a new test. (Rheem, No. 31 at
pp. 3-4)
Further, DOE notes that although manufacturers of consumer water
heaters are not authorized to use an AEDM under 10 CFR 429.70(c) to
determine ratings for consumer water heaters, as discussed,
manufacturers may determine UEF for certain models using the methods
specified under 10 CFR 429.70(g). These models include: (1) gas-fired
basic models differing only in whether the basic models use natural gas
or propane and with an input rating within 10 percent and (2) electric
storage water heater basic models differing only in heating element
input rating (in addition, for untested basic models with a heating
element with an input rating that is lower than the input rating of the
corresponding element in the tested basic model, the FHR for the
untested basic model must also result in the same draw pattern as was
applied to the tested basic model). These provisions already provide
manufacturers with some measure of an alternative method of rating
consumer water heaters without testing every model, and this
alternative method reduces manufacturer test burden. Further, DOE
explained in a 2013 final rule pertaining to AEDMs that the AEDM
provisions extend to those products or equipment which have ``expensive
or highly-customized basic models.'' 78 FR 79579, 79580 (Dec. 31,
2013). The current AEDM provisions for commercial HVAC equipment
(including commercial water heaters, for example) were in part the
result of a negotiated rulemaking effort by the Appliance Standards and
Rulemaking Federal Advisory Committee (ASRAC) in 2013. Id. Consumer
water heaters were not considered at the time.\78\ Id In this
rulemaking, DOE did not receive comments indicating that these
conditions would apply for consumer water heaters or residential-duty
commercial water heaters, and, hence, DOE has determined that modeling-
based AEDMs are not required at this time. Additionally, the test
method adopted in this final rule has been determined to be
representative of energy use over an average use cycle without being
unduly burdensome.
---------------------------------------------------------------------------
\78\ Working group meeting transcripts can be found at
www.regulations.gov under Docket No. EERE-2013-BT-NOC-0023.
---------------------------------------------------------------------------
Given these factors, DOE is not considering further expansion of
the AEDM provisions for water heaters within the scope of this test
procedure, aside from applying the untested model provisions to
electric instantaneous water heaters, as discussed in section III.G.2
of this document. The following sections discuss representations of the
FHR value of certain untested models and the extension of the
alternative rating method to electric instantaneous-type water heaters.
1. Representations of First-Hour Ratings for Untested Basic Models
The provisions at 10 CFR 429.70(g) allow for an untested electric
storage water heater basic model with element wattages less than a
tested basic model to use the FHR of the tested basic model, provided
that the untested basic model's FHR is in the same draw pattern as the
tested basic model. For an untested basic model with an element wattage
that is lower than the tested basic model's, the tested FHR of the
untested basic model will generally be less than the FHR of the tested
basic model. In such cases, using the tested basic model's FHR to
represent the untested model's FHR may not be as
[[Page 40463]]
representative as using the FHR value directly determined from the
untested model (the FHR of the untested basic model is determined
pursuant to the procedures in appendix E specifically for the purpose
of allowing use of the tested basic model's UEF rating). Instead, using
the untested basic model's measured FHR for representation purposes,
rather than the tested model's FHR (as currently required), could
increase the representativeness of the certified FHR, while potentially
not increasing burden on the manufacturer.
The January 2022 NOPR requested comment on the potential to revise
the existing provisions at 10 CFR 429.70(g)(2)(ii) for electric storage
water heaters with element wattages less than the tested basic model to
require that the represented FHR of the untested model be the untested
basic model's FHR as determined according to the procedures at appendix
E. Specifically, DOE sought information on whether manufacturers
collect sufficient data to establish a rated value of FHR based on FHR
testing for untested basic models, subject to the sampling plan
requirements at 10 CFR 429.17 (i.e., whether manufacturers currently
measure the FHR of at least two units of an untested basic model to
ensure it is in the same draw pattern bin as the tested model). 87 FR
1554, 1587-1588 (Jan. 11, 2022).
In commenting on this issue, ASAP, ACEEE, and NCLC supported
revising the untested provisions for storage water heaters so that the
first-hour ratings for untested models are used for ratings. Likewise,
ASAP, ACEEE, and NCLC also supported requiring that the represented
value of max GPM for untested electric instantaneous water heaters be
the actual value determined for the untested model. (ASAP, ACEEE, and
NCLC, No. 34 at p. 3)
BWC offered a different view, commenting that the current AEDM
provisions yield accurate results for untested electric storage water
heaters with element wattages less than the tested basic models. The
company stated that changing these provisions would result in
significant burden for manufacturers without producing significantly
different results. BWC also urged DOE to not apply the more stringent
AEDM requirements for electric storage water heaters to electric
instantaneous water heaters. (BWC, No. 33 at pp. 10-11)
Similarly, AHRI raised concerns about the increased burden
associated with the proposed additional requirements for alternate
electric storage water heater input ratings. (AHRI, No. 40 at p. 3)
AHRI indicated that, because the sampling plan provisions at 10 CFR
429.17 are not currently required when certifying untested models,
manufacturers would have to retest and recertify untested models if DOE
were to adopt such requirements. (AHRI, No. 40 at pp. 5-6) A.O. Smith
requested additional clarity on exactly which untested models would
need to be tested to confirm FHR ratings under the proposed untested
provisions. (A.O. Smith, Jan. 27, 2022 Public Meeting Transcript, No.
27 at pp. 48-49) A.O. Smith claimed that the established practice has
been to evaluate untested electric storage water heater tank inputs to
confirm that these models would perform in the same draw pattern as the
tested model. A.O. Smith also stated that certifying data for untested
models would be an extra testing burden for manufacturers which have
relied on the procedures pursuant to alternative methods for
determining energy efficiency and energy use to establish the ratings,
and, therefore, the commenter recommended against the Department
changing the relevant data collection methodology. (A.O. Smith, No. 37
at pp. 4-5)
After consideration of the comments and the additional burden that
an amendment relating to the FHR representations for certain untested
water heaters would impose, DOE has decided not to amend these
provisions at this time. However, DOE reiterates that, per the current
AEDM requirements, manufacturers are required to test the FHR of an
untested model prior to making a determination as to whether or not the
untested model will fall under the same draw pattern as the tested
model. This determination should not be made on the basis of input
rates alone. Manufacturers should consult 10 CFR 429.70(g), which
states, ``simulations or other modeling predictions for ratings of the
uniform energy factor, volume, first-hour rating, or maximum gallons
per minute (GPM) are not permitted.'' Furthermore, as a clarification
of the existing reporting requirements, manufacturers using the
untested provisions to certify certain water heater models to DOE must
identify these models as being tested to an AEDM (see 10 CFR
429.17(b)(1), which references 10 CFR 429.12).
2. Alternative Rating Method for Electric Instantaneous Water Heaters
In the January 2022 NOPR, in response to earlier stakeholder
comments, DOE proposed to expand the untested provisions (described in
detail in section III.G.1 of this document) so as to apply similar
provisions to electric instantaneous water heaters. The proposed
expansion would allow electric instantaneous water heaters and electric
storage water heaters to have similar AEDM requirements. 87 FR 1554,
1588 (Jan. 11, 2022).
As discussed in further detail in the January 2022 NOPR, because
electric instantaneous water heaters exhibit the same trends in
performance that justify the use of an alternative rating determination
method for electric storage water heaters, DOE tentatively determined
that extending the use of the untested provisions to electric
instantaneous water heaters in 10 CFR 429.70(g) would maintain a
representative rating of these products' energy efficiency, while
reducing manufacturer burden. Therefore, DOE proposed to permit use of
the untested provisions for electric instantaneous water heaters
through newly proposed provisions at 10 CFR 429.70(g)(3). Specifically,
the January 2022 NOPR proposed that the criteria that currently apply
to electric storage water heaters at 10 CFR 429.70(g)(2) would apply to
electric instantaneous type water heaters at 10 CFR 429.70(g)(3), with
the exceptions that: (1) The criteria for electric instantaneous water
heaters would reference the maximum GPM rather than the FHR, as FHR
applies only to storage water heaters; and (2) the criteria for
electric instantaneous water heaters would reference the ``input rate''
rather than the ``heating element'' or ``input rating for the
corresponding heating element.''. 87 FR 1554, 1588 (Jan. 11, 2022).
On this topic, AHRI and A.O. Smith expressed support for the
inclusion of electric instantaneous water heaters in the untested
provisions. (AHRI, No. 40 at pp. 5-6; A.O. Smith, No. 37 at p. 2) Based
upon its previous reasoning and after considering the relevant
comments, DOE is adopting the untested provisions for electric
instantaneous water heaters as proposed in the January 2022 NOPR, with
only a minor modification.
Section III.H.1 of this document discusses terminology used with
respect to storage vs. instantaneous and flow-activated vs. non-flow-
activated water heaters. Specifically, DOE has determined that not all
instantaneous water heaters are flow-activated, and also that storage
water heaters do not necessarily have to be non-flow-activated, either.
As such, in this final rule, DOE is amending the language in all of the
untested provisions (those which currently exist and those which are
being newly established) such that the delivery capacity metric may be
either FHR or Max GPM. This correction
[[Page 40464]]
will harmonize the requirements at 10 CFR 429.70(g) with the test
procedure, which specifies that the Max GPM metric is for flow-
activated water heaters, and the FHR metric is for all others,
regardless of the water heater's classification as storage-type or
instantaneous-type (see section 5.3 of appendix E).
H. Corrections and Clarifications
DOE is adopting certain corrections and clarifications to the
appendix E test procedure that are intended to improve the
repeatability and reproducibility of the test procedure. These changes
are described in more detail in the subsections that follow.
1. Flow-Activated Terminology
In sections 5.3.3.1 and 5.3.3.2 of appendix E, which describe
general requirements and draw initiation criteria, respectively, for
the FHR test, the term ``storage-type water heaters'' is used. However,
the FHR test applies to all water heaters that are not flow-activated,
which includes non-flow-activated instantaneous water heaters. In this
rulemaking, DOE sought feedback on updating the phrase ``storage-type
water heaters'' in section 5.3.3 to ``non-flow-activated water
heaters.'' 85 FR 21104, 21112 (April 16, 2020). Multiple stakeholders
provided comments on the use of ``flow-activated'' and ``non-flow-
activated'' in response to the April 2020 RFI and the January 2022
NOPR.
Initially, commenters such as AHRI and some manufacturers stated
that there is no need to change the phrase ``storage-type water
heaters'' in section 5.3.3 of appendix E. However, when DOE submitted a
comment to the ASHRAE 118.2 drafting committee suggesting the change
from ``storage-type'' to ``non-flow activated'' in the corresponding
sections of ASHRAE 118.2, this change was accepted by the committee and
used in ASHRAE 118.2-2022. Thus, DOE proposed to update the terminology
in the January 2022 NOPR in an effort to align terminology with that
recognized by industry. 87 FR 1554, 1576 (Jan. 11, 2022).
Specifically, section 7.3.3.1 of ASHRAE 118.2-2022 uses the term
``non-flow-activated'' water heaters, whereas section 5.3.3.1 of the
current appendix E test procedure uses the term ``storage-type'' water
heaters. Yet section 7.3.3.2 of ASHRAE 118.2-2022 still uses the
``storage-type'' term that is present in section 5.3.3.2 of appendix E.
By contrast, DOE's proposal, as delineated in the January 2022 NOPR,
would effectively ensure that language related to the FHR test did not
inadvertently narrow the scope of that test to only storage-type water
heaters whenever the term ``storage-type'' was used in this context.
On this topic, Rheem supported the proposed amendments to the
language throughout appendix E to use ``non-flow activated'' and
``flow-activated,'' and to refer to water heaters with or without
storage volumes greater than 2 gallons as such. Rheem stated that these
changes eliminate the storage or instantaneous type language except
where helpful to navigate the appendix. (Rheem, No. 31 at p. 2)
Many commenters expressed confusion regarding DOE's proposed
changes in terminology in appendix E, however. At the public meeting
webinar for the January 2022 NOPR, AHRI requested further explanation
of the intent behind the proposed terminology update changing
``storage-type'' and ``instantaneous-type'' to ``non-flow-activated''
and ``flow-activated,'' especially since the proposed terms are not
used in EPCA. AHRI requested that DOE clarify whether or not the
terminology change would have any impact on testing. (AHRI, Jan. 27,
2022 Public Meeting Transcript, No. 27 at pp. 41-42) In its written
comments, AHRI stated that replacing the ``instantaneous-type'' and
``storage-type'' terminology with ``flow-activated'' and ``non-flow
activated'' may cause confusion for the test methods relevant to water
heaters larger than 20 gallons in rated storage volume. AHRI suggested
that DOE should consider adding steps to the test procedure to
determine: (1) if a unit is ``storage-type'' or ``instantaneous-type''
and (2) if a unit is ``flow-activated'' or ``non-flow activated.''
(AHRI, No. 40 at p. 4) BWC did not support a change from the terms
``storage-type'' and ``instantaneous-type'' to ``non-flow-activated''
and ``flow-activated'' for water heaters above 20 gallons, stating that
it would create confusion for manufacturers and testing laboratories.
(BWC, No. 33 at p. 6)
AET commented that a flow-activated electric instantaneous water
heater will need to be able to heat its stored volume of water to the
67 [deg]F temperature rise in appendix E in no more than about 30
seconds based on a calculation of recovery efficiency and flow rate.
(AET, No. 29 at pp. 3-5) However, DOE notes that this calculation is
only possible because the recovery efficiency of an electric resistance
water heater is defined as 98 percent in the appendix E test procedure;
the time criterion would vary for other types of water heaters.
Furthermore, AET commented that DOE should be careful in its use of
the term ``instantaneous'' water heater to ensure the test procedure
for these products applies to all products which have more than 4,000
Btu/h of input per gallon of storage, adding that there are
instantaneous water heaters have several gallons of storage capacity or
are thermostatically-activated (which should be tested under a non-
flow-activated test method). The commenter stressed that water heaters
should be tested per the flow-activated or non-flow-activated test
method based on whether or not they are indeed flow-activated, and not
whether they are instantaneous-type or storage-type. AET commented that
a thermostatically-activated unit does not necessarily mean that stored
water is kept fully heated, but rather that the rate of change of
temperature of stored water can be used to indicate whether a flow is
occurring, and, therefore, the distinction between flow-activation and
non-flow-activation (i.e., thermostatic activation) may be difficult to
make for water heaters with very small volumes. AET claimed that hybrid
instantaneous water heaters activated by both flow and water
temperature are under development, and such appliances should be
addressed in the test procedure. AET also noted that the largest
possible instantaneous-type gas-fired unit may have up to 50 gallons of
storage volume per the codified definitions, and the largest possible
instantaneous-type oil-fired unit may have up to 52.5 gallons of
storage volume. Additionally, AET provided detailed comments indicating
that not all instantaneous water heaters are flow-activated within the
scope of the standards of consumer water heaters, so DOE should not use
the terms interchangeably. (AET, No. 29 at pp. 2-6)
To clarify the intent of the January 2022 NOPR's proposal: DOE
agrees with AET that the distinction between storage-type water heaters
and instantaneous-type water heaters is different from the distinction
between flow-activated water heaters and water heaters with other
activation schemes. Comments from manufacturers seem to indicate that
there could be a misconception that ``instantaneous-type water heater''
and ``flow-activated water heater'' are interchangeable, because these
comments opposed DOE's correction to remove the ``storage-type'' term
from the description of the FHR test and replace it with the ``non-
flow-activated'' term; however, these terms are not interchangeable.
When a water heater is referred to as ``storage-type'' or
``instantaneous-type,'' those terms specifically refer to the ratio
between
[[Page 40465]]
the storage volume and the input rate. These terms are defined in EPCA
(see 42 U.S.C. 6291(27)(A) and (B)) and at 10 CFR 430.2. For example,
DOE's energy conservation standards at 10 CFR 430.32(d) distinguish
between storage-type and instantaneous-type water heaters. Section 1.6
of appendix E defines ``flow-activated'' as an operational scheme in
which a water heater initiates and terminates heating based on sensing
flow in order to determine which method of testing is most appropriate
for the water heater's operational scheme. Therefore, whether a water
heater is storage-type or instantaneous-type has no bearing on whether
it is determined to be ``flow-activated.'' There. can be flow-activated
storage water heaters or even non-flow-activated instantaneous water
heaters. In fact, circulating water heaters are defined as non-flow-
activated instantaneous water heaters (see section III.A.4.a of this
final rule).
Section 5.3.1 of appendix E states, ``For flow-activated water
heaters, conduct the maximum GPM test, as described in section 5.3.2,
Maximum GPM Rating Test for Flow-Activated Water Heaters, of this
appendix. For all other water heaters, conduct the first-hour rating
test as described in section 5.3.3 of this appendix.'' In this final
rule, the Department is maintaining this requirement in the revised
appendix E test procedure.
With respect to comments related to how to determine whether a
water heater is flow activated, DOE has concluded that the definition
of ``flow-activated'' in proposed section 1.6 of appendix E is
sufficient for manufacturers and testing laboratories to determine
whether a product meets that definition. Specifically, if a water
heater initiates or terminates heating as a result of sensing flow--
regardless of what type of sensor is used to determine whether a flow
is occurring--then the water heater is flow-activated. If a water
heater has two activation schemes, one of which is based on sensing
flow (e.g., heating can also be initiated due to the tank temperature
crossing below a certain thermostat limit), then it still meets the
description of a flow-activated water heater, and, therefore, must be
tested as such. This is a clarification of the current test procedure
and not an amendment, and, thus, DOE is maintaining the language in the
definition of ``flow-activated'' in appendix E (which will now appear
at section 1.7).
DOE understands that the term ``non-flow-activated,'' which was
used in the January 2022 NOPR's proposal, could be a source of
confusion, because, as AET states, there are products which are dually
activated. Hence, in this final rule, DOE is not introducing this term
into the appendix E test procedure. Instead, DOE is striking out the
references to storage-type water heaters in provisions related to water
heaters which require the FHR test and striking out the reference to
instantaneous-type water heaters in provisions related to water heaters
which require the Max GPM test. Because section 5.3.1 already instructs
which test is required, these instances of the terms ``storage-type''
and ``instantaneous-type'' are inaccurate and extraneous. DOE has
determined that these corrections and clarifications do not change the
way in which the appendix E test procedure is conducted.
2. Second Identical 24-Hour Simulated-Use Test
For water heaters that are not flow-activated, the water heaters
test procedure in section 5.2.2.2 of the currently applicable appendix
E includes directions for setting the temperature controllers such that
the test method is repeatable and reproducible.
A.O. Smith requested DOE to clarify that, when testing water
heaters larger than or equal to 20 gallons, the second identical
simulated-use test is not a requirement of the procedure but only a
means by which to validate the stability of the setting, if it is
deemed necessary to perform. (A.O. Smith, No. 37 at p. 7)
In response, the Department notes that there is no requirement for
a second identical 24-hour simulated-use test in appendix E. Sections
5.2.2.2.1.1 and 5.2.2.2.1.2 of the currently applicable test procedure
states that once the proper temperature control setting is achieved,
the setting must remain fixed for the duration of the first-hour rating
test and the simulated-use test such that a second identical simulated-
use test run immediately following the one specified in section 5.4
would result in average delivered water temperatures that are within
the bounds specified in section 2.4 of this appendix. This language was
included to explain the intent of the temperature control. However, for
units which have an integrated mixing valve or that are intended for
use with a mixing valve, the language describing the second identical
24-hour simulated-use test may be misleading, as there may be
individual draws where the outlet temperature is outside the bounds
specified in section 2.4 of appendix E. As a result, the Department is
amending the language to remove reference to a second 24-hour
simulated-use test. The procedure to ensure the stability of the
temperature control as described in sections 5.2.2.2.1.1 and
5.2.2.2.1.2 remains unchanged.
3. Connected Products
Section 5.1 of appendix E currently specifies the operational mode
selection for water heaters but does not explicitly address ``smart''
or ``connected'' modes of operation. For water heaters that allow for
multiple user-selected operational modes, all procedures specified in
appendix E must be carried out with the water heater in the same
operational mode (i.e., only one mode). This operational mode must be
the default mode (or similarly named, suggested mode for normal
operation) as defined by the manufacturer in its product literature for
giving selection guidance to the consumer.
On September 17, 2018, DOE published an RFI seeking information on
the emerging smart technology appliance and equipment market. 83 FR
46886 (September 2018 RFI). In the September 2018 RFI, DOE sought
information to better understand market trends and issues in the
emerging market for appliances and commercial equipment that
incorporate smart technology. Id. at 83 FR 46887. DOE's intent in
issuing the September 2018 RFI was to ensure that DOE did not
inadvertently impede such innovation when fulfilling its statutory
obligations to set efficiency standards for covered products and
equipment. Id. In the April 2020 RFI, DOE sought comment on the same
issues presented in the September 2018 RFI as they may be specifically
applicable to consumer water heaters. 85 FR 21104, 21114 (April 16,
2020).
Responding to the April 2020 RFI, commenters urged DOE to update
the test procedure to better capture the performance differences
between traditional and connected products, provided some recommended
definitions delineating the types of connected products, and suggested
that DOE adopt additional and/or optional performance metrics related
to grid connectivity. These comments are discussed in detail in the
January 2022 NOPR. 87 FR 1554, 1585 (Jan. 11, 2022). In the January
2022 NOPR, DOE proposed to explicitly state that any connection to an
external network or control would be disconnected during testing. DOE
proposed this given that there were insufficient data on consumer usage
of connected features for the Department to develop a representative
test configuration for assessing the energy consumption of connected
functionality for water
[[Page 40466]]
heaters. 87 FR 1554, 1585-1586 (Jan. 11, 2022).
On this topic, BWC agreed with DOE's tentative determinations and
clarifications regarding the testing of connected water heaters. (BWC,
No. 33 at p. 9) NYSERDA recommended that DOE ensure the test procedure
supports grid-enabled water heaters specifically, as well as connected
water heaters generally. To this point, NYSERDA recommended that DOE
should specify how manufacturers can demonstrate their products are
``connected'' and include this as an item for reporting to the agency.
NYSERDA encouraged DOE to consider the power usage for connectedness,
as this would be informative for utilities planning for
decarbonization. Additionally, NYSERDA stated that including the power
usage for connected functions would encourage the load to be minimal
and better inform consumers regarding anticipated operating costs.
(NYSERDA, No. 32 at pp. 2-3)
In response, while DOE acknowledges the potential benefits that
could be provided by connected capability, such as providing energy
saving benefits to consumers and enabling peak load shifting on the
grid, the Department has concluded that requiring measurement and
reporting of the energy consumed by connected features at this time may
prematurely hinder the development and incorporation of such features
in water heaters. As such, DOE is clarifying that connected features on
water heaters should remain on but disconnected from any external
network or control for the duration of the appendix E test. This
approach will allow some baseline energy consumption to be accounted
for without imposing any specific network connection test requirements.
4. Heating Value of Gas
In this rulemaking, DOE considered the need for a clarification
regarding the correction of the heating value to a standard temperature
and pressure. Section 3.7 of appendix E states that the heating values
of natural gas and propane must be corrected from those reported at
standard temperature and pressure conditions to provide the heating
value at the temperature and pressure measured at the fuel meter, but
does not specify standard temperature and pressure conditions. Without
a specified standard temperature and pressure, the heating values used
in calculations may not be consistent from laboratory to laboratory.
As discussed in the January 2022 NOPR, there are several sources
which do specify the standard temperature and pressure conditions for
natural gas calculations. 87 FR 1554, 1578 (Jan. 11, 2022). For
example, AHRI maintains an Operations Manual for Residential Water
Heater Certification Program (AHRI Operations Manual), which includes
an equation that corrects the measured heating value, when using a dry
gas and a wet test meter, to the heating value at the standard
temperature and pressure of 60 [deg]F (15.6 [deg]C) and 30 inches of
mercury column (101.6 kPa), respectively. Annex B of the March 2019
ASHRAE Draft 118.2 also provides a method for correcting the heating
value from measured to standard conditions, which allows for the use of
either dry or saturated gas and either a dry or wet test meter--and
this calculation was finalized in ASHRAE 118.2-2022 with an example
provided for 60 [deg]F (15.6 [deg]C) and 30 inches of mercury column
(101.6 kPa). Lastly, sections 2.4.1 and 3.1.1 of appendix O to subpart
B of 10 CFR part 430 (Uniform Test Method for Measuring the Energy
Consumption of Vented Home Heating Equipment) correct the input rate to
the standard conditions of 60 [deg]F (15.6 [deg]C) and 30 inches of
mercury column (101.6 kPa). Therefore, to align with the AHRI
Operations Manual and the current practice in other appendices within
part 430 of the CFR, DOE proposed in the January 2022 NOPR to establish
the standard temperature and pressure conditions for gas measurements
as 60 [deg]F (15.6 [deg]C) and 30 inches of mercury column (101.6 kPa),
respectively. Further, DOE proposed to adopt the method used in Annex B
of a finalized ASHRAE 118.2-2022 to correct the heating value of gas to
standard conditions. 87 FR 1554, 1578 (Jan. 11, 2022).
DOE did not receive comments from stakeholders regarding this
proposal. Accordingly, DOE is adopting these proposals in this final
rule for the reasons previously discussed.
I. Effective and Compliance Dates
The effective date for the adopted test procedure amendments will
be 30 days after publication of this final rule in the Federal
Register.
As to the compliance date, EPCA prescribes that all representations
of energy efficiency and energy use for consumer products (including
consumer water heaters),), including those made on marketing materials
and product labels, must be made in accordance with an amended test
procedure, beginning 180 days after publication of the final rule in
the Federal Register. (42 U.S.C. 6293(c)(2)) For residential-duty
commercial water heaters, this requirement is beginning 360 days after
publication of the final rule in the Federal Register. (42 U.S.C.
6314(d)(1)) For consumer products, EPCA provides an allowance for
individual manufacturers to petition DOE for an extension of the 180-
day period if the manufacturer may experience undue hardship in meeting
the deadline. (42 U.S.C. 6293(c)(3)) To receive such an extension,
petitions must be filed with DOE no later than 60 days before the end
of the 180-day period and must detail how the manufacturer will
experience undue hardship. (Id.)
With the exception of two test method provisions (i.e., high
temperature testing and separate storage tank testing), compliance with
the modified test procedure adopted in this final rule is required for
consumer water heaters beginning 180 days after the date of publication
of this final rule in the Federal Register. Similarly, with the
exception of the separate storage tank testing requirement, compliance
with the modified test procedure is required for residential-duty
commercial water heaters beginning 360 days after the date of
publication of this final rule in the Federal Register.
Beginning on the effective date of this final rule, the use of the
high temperature test method (section 5.1.2 of the amended appendix E
test procedure) will be allowed for voluntary additional
representations until the compliance date of amended energy
conservation standards for consumer water heaters that address high
temperature operation, should such standards be adopted. Until such a
time, the normal temperature test method (section 5.1.1 of the amended
appendix E test procedure) is required as the basis for ratings used to
determine compliance with energy conservation standards. During this
voluntary usage period, manufacturers who choose to publish two sets of
ratings must clearly indicate which values correspond to the high
temperature test method. In the standards rulemaking, DOE plans to
clarify which type(s) of water heaters would be required to utilize the
high temperature test method when determining compliance with potential
amended standards.
The use of the separate storage tank test method for circulating
water heaters (section 4.10 of the amended appendix E test procedure)
will be allowed for voluntary representations and compliance with
standards beginning on the effective date of this final rule. This test
method will become mandatory when compliance with amended energy
conservation standards for consumer water heaters and
[[Page 40467]]
residential-duty commercial water heaters is required, should such
standards addressing circulating water heaters be adopted.
Upon the compliance date of test procedure provisions in this final
rule, any waivers that had been previously issued and are in effect
that pertain to issues addressed by such provisions are terminated. 10
CFR 430.27(h)(3) and 431.401(h)(3). Recipients of any such waivers are
required to test the products subject to the waiver according to the
amended test procedure as of the compliance date of the amended test
procedure. The amendments adopted in this document pertain to issues
addressed by a waiver granted to Bradford White Corporation (Case No.
2019-006). See 85 FR 5648 (Jan. 31, 2020). On January 31, 2020, DOE
published a Notice of Decision and Order in the Federal Register
granting Bradford White Corporation a waiver for a specified basic
model that experiences the first cut-out of the 24-hour simulated-use
test during a draw. 85 FR 5648. The Decision and Order requires
Bradford White Corporation to use an alternate test procedure that DOE
determined more accurately calculates the recovery efficiency when the
first cut-out occurs during a draw. Id. at 85 FR 5651. As described in
section III.B.2.b of this document, DOE is adopting the alternate test
procedure prescribed in the Decision and Order granted to Bradford
White Corporation into the test procedure at appendix E.
J. Test Procedure Costs
EPCA requires that test procedures proposed by DOE not be unduly
burdensome to conduct. (42 U.S.C. 6293(b)(3)) The following sections
discuss DOE's evaluation of estimated costs associated with the
proposed amendments for consumer water heaters and residential-duty
commercial water heaters.
1. Separate Storage Tanks
In the January 2022 NOPR, DOE tentatively concluded that the cost
of running the test procedure using an 80-gallon unfired hot water
storage tank should be the same as testing a water heater with an
integrated tank with a comparable storage volume. The Department
estimated that testing a fossil fuel-fired or electric storage water
heater would cost approximately $3,000 and that testing an electric
storage water heater which uses heat pump technology would cost
approximately $4,500. In addition to the testing cost, the manufacturer
or third-party testing facility would incur a one-time cost to purchase
an unfired hot water storage tank which are commercially available for
approximately $900. 87 FR 1554, 1589 (Jan. 11, 2022).
In the July 2022 SNOPR, DOE revised its proposal. DOE estimated
that, for gas-fired circulating water heaters, these proposed changes
could require a one-time purchase of an 80- to 120-gallon unfired hot
water storage tank, which are readily commercially available for
approximately $2,000. For heat pump-only water heaters, the proposed
changes could result in a one-time purchase of a 40-gallon (4 gallons) electric storage water heater readily available for
approximately $500. 87 FR 42270, 42283 (July 14, 2022).
DOE evaluated stakeholder feedback regarding this testing
requirement and further revised its amended provision. This final rule
adopts the following changes concerning the testing of circulating
water heaters:
(1) Gas-fired circulating water heaters be tested using an unfired
hot water storage tank with a storage volume between 80 and 120 gallons
and an R-value exactly at the minimum R-value required at 10 CFR
431.110(a).
(2) Heat pump circulating water heaters be tested using a 40-gallon
(5 gallons) electric storage water heater at the minimum
UEF standard required at 10 CFR 430.32(d).
AHRI generally agreed with the estimated costs presented in the
January 2022 NOPR, with the exception that $900 may be an underestimate
of the cost of purchasing an unfired hot water storage tank. (AHRI, No.
40 at p. 3) No further comments on test costs were received in response
to the July 2022 SNOPR. Based upon its subsequent review in light of
AHRI's comment, DOE notes that its estimate for the retail price of an
unfired hot water storage tank has been raised from $900 to $2,000.
In response, DOE recognizes that these amendments will require
manufacturers to make one-time purchases of the necessary storage tanks
for each testing facility. DOE's research indicates that the tanks
required for testing gas-fired circulating water heaters and heat pump
circulating water heaters are commercially available at retail prices
of $2,000 and $500, respectively, thereby reflecting third-party
laboratory testing costs.
These amendments to appendix E regarding storage tank requirements
will allow affected models to be certified for the first time.
Manufacturers will not be able to rely on data generated under test
procedures in effect prior to this final rule.
2. Method for Determining Internal Tank Temperature for Certain Water
Heaters
This final rule amends section 5.4 of appendix E by the addition of
section 5.4.2.2, which allows internal tank temperature to be estimated
by removing water from the water heater for models with rated storage
volumes greater than or equal to 2 gallons whose internal tank
temperatures are unable to be measured using thermocouples.
DOE estimates that this testing method may extend test duration by
up to 8 hours as part of the final standby period of the 24-hour
simulated use test. This additional duration is estimated to increase
testing costs by up to $1,000 for affected fossil-fuel-fired and
electric water heaters and $1,500 for affected heat pump water heaters.
The addition of section 5.4.2.2 to appendix E will allow affected
models to be certified for the first time. Because these water heaters
could not previously be accurately tested, manufacturers will not be
able to rely on data generated under test procedures in effect prior to
this final rule.
3. High Temperature Testing
DOE recognizes that the amendment specifying the high temperature
testing method would likely cause UEF ratings for any products that
would become subject to this test method (i.e., a subset of electric
resistance storage water heaters) to decrease if they are currently
certified using a default temperature setting. In order to limit
potential retesting and recertification burden for manufacturers, any
requirement to test certain products using the high temperature testing
method will be established only once DOE completes its ongoing reviews
of potential amended energy conservation standards for consumer water
heaters, should such standards be adopted. The cost to test per this
amended method would not be different from the cost to test per the
method in the currently applicable appendix E test procedure (i.e.,
testing an electric storage water heater would cost approximately
$3,000).
4. Additional Amendments
The remainder of the test procedure amendments adopted in this
final rule will not impact test costs.
DOE is amending section 2.5 of appendix E, ``Set Point
Temperature,'' to allow low-temperature water heaters to deliver water
at the maximum outlet temperature that they are capable of producing.
This aligns with how these products are tested currently. Manufacturers
already should have
[[Page 40468]]
requested a waiver for these products, as the current test procedure
cannot be used as written to test low-temperature water heaters. As
these products are currently tested and rated to the procedures which
DOE is adopting, there should be no additional cost associated with
this change.
DOE is also amending the existing test procedure for consumer and
residential-duty commercial water heaters by modifying the flow rate
requirements during the FHR test for water heaters with a rated storage
volume less than 20 gallons. This change does not significantly affect
the test results of the FHR test, and, thus, DOE expects that
manufacturers may rely on existing test data where available. Further,
storage-type water heaters (which comprise the majority of water
heaters that need to be tested for an FHR rating) with less than 20
gallons of rated storage volume currently do not have energy
conservation standards codified at 10 CFR 430.32(d) and are, therefore,
not rated and certified to DOE. Instantaneous-type water heaters that
will require an FHR rating are expected to be circulating water
heaters, and this final rule amends the appendix E test procedure in
such a way that allows these products to be tested and rated for the
first time (test costs for water heaters requiring separate storage
tanks are discussed in section III.J.1 of this document). Therefore,
the update to the FHR test method does not change the expected testing
costs for products which have been tested per appendix E previously.
DOE is also amending the timing of the first measurement in each
draw of the 24-hour simulated-use test and the test condition
specifications and tolerances, including electric supply voltage
tolerance, ambient temperature, ambient dry-bulb temperature, ambient
relative humidity, standard temperature and pressure definition, gas
supply pressure, and manifold pressure. These changes are intended to
reduce retesting associated with having a single measurement out of
tolerance, while maintaining the current representativeness of the test
conditions and the stringency of the tolerances for the test
conditions. DOE also has determined that the amendment to the flow rate
tolerances for water heaters less than 2 gallons in rated storage
volume would not alter the measured efficiency of consumer water
heaters and residential-duty commercial water heaters, nor require
retesting or recertification. In the absence of an explicit instruction
for the flow rate tolerance applicable to water heaters with rated
storage volume under 2 gallons, DOE expects that general industry best
practice is to apply the flow rate tolerances being adopted for section
5.4.3 of appendix E for water heaters with rated storage volume less
than 2 gallons (based on DOE's review of third-party laboratory test
data), such that this proposal is expected to be consistent with
current methodology.
Manufacturers will be able to rely on data generated under the
current water heaters test procedure for the remainder of the
amendments set forth in this final rule, so accordingly, such changes
should result in no associated increase in costs.
IV. Procedural Issues and Regulatory Review
A. Review Under Executive Orders 12866, 13563, and 14094
Executive Order (E.O.) 12866, ``Regulatory Planning and Review,''
58 FR 51735 (Oct. 4, 1993), as supplemented and reaffirmed by E.O.
13563, ``Improving Regulation and Regulatory Review,'' 76 FR 3821 (Jan.
21, 2011) and E.O. 14094, ``Modernizing Regulatory Review,'' 88 FR
21879 (April 11, 2023), requires agencies, to the extent permitted by
law, to: (1) propose or adopt a regulation only upon a reasoned
determination that its benefits justify its costs (recognizing that
some benefits and costs are difficult to quantify); (2) tailor
regulations to impose the least burden on society, consistent with
obtaining regulatory objectives, taking into account, among other
things, and to the extent practicable, the costs of cumulative
regulations; (3) select, in choosing among alternative regulatory
approaches, those approaches that maximize net benefits (including
potential economic, environmental, public health and safety, and other
advantages; distributive impacts; and equity); (4) to the extent
feasible, specify performance objectives, rather than specifying the
behavior or manner of compliance that regulated entities must adopt;
and (5) identify and assess available alternatives to direct
regulation, including providing economic incentives to encourage the
desired behavior, such as user fees or marketable permits, or providing
information upon which choices can be made by the public. DOE
emphasizes as well that E.O. 13563 requires agencies to use the best
available techniques to quantify anticipated present and future
benefits and costs as accurately as possible. In its guidance, the
Office of Information and Regulatory Affairs (OIRA) in the Office of
Management and Budget (OMB) has emphasized that such techniques may
include identifying changing future compliance costs that might result
from technological innovation or anticipated behavioral changes. For
the reasons stated in the preamble, this final regulatory action is
consistent with these principles.
Section 6(a) of E.O. 12866 also requires agencies to submit
``significant regulatory actions'' to OIRA for review. OIRA has
determined that this final regulatory action does not constitute a
``significant regulatory action'' under section 3(f) of E.O. 12866.
Accordingly, this action was not submitted to OIRA for review under
E.O. 12866.
B. Review Under the Regulatory Flexibility Act
The Regulatory Flexibility Act (5 U.S.C. 601 et seq.) requires
preparation of a final regulatory flexibility analysis (FRFA) for any
final rule where the agency was first required by law to publish a
proposed rule for public comment, unless the agency certifies that the
rule, if promulgated, will not have a significant economic impact on a
substantial number of small entities. As required by Executive Order
13272, ``Proper Consideration of Small Entities in Agency Rulemaking,''
67 FR 53461 (August 16, 2002), DOE published procedures and policies on
February 19, 2003 to ensure that the potential impacts of its rules on
small entities are properly considered during the DOE rulemaking
process. 68 FR 7990. DOE has made its procedures and policies available
on the Office of the General Counsel's website: www.energy.gov/gc/office-general-counsel. DOE reviewed this final rule under the
provisions of the Regulatory Flexibility Act and the procedures and
policies published on February 19, 2003.
DOE is amending test procedures for consumer water heaters and
residential-duty commercial water heaters. DOE is publishing this final
rule in satisfaction of the 7-year-lookback review requirement
specified in EPCA. (42 U.S.C. 6293(b)(1)(A); 6314(a)(1)) Further,
amending test procedures for consumer and residential-duty commercial
water heaters assists DOE in fulfilling its statutory deadline for
amending energy conservation standards for products and equipment that
achieve the maximum improvement in energy efficiency that is
technologically feasible and economically justified. (42 U.S.C.
6295(o)(2)(A); 42 U.S.C. 6313(a)(6)) Additionally, amending test
procedures for consumer and residential-duty commercial water heaters
allows manufacturers to produce measurements of energy efficiency that
[[Page 40469]]
are representative of an average use cycle and uniform for all
manufacturers.
On January 11, 2022, DOE published a test procedure NOPR (January
2022 NOPR) in the Federal Register proposing to amend the test
procedure for consumer water heaters and residential-duty commercial
gas water heaters. See 87 FR 1554. DOE published a supplemental test
procedure NOPR on July 14, 2022 (July 2022 SNOPR) in the Federal
Register, proposing certain modifications to the January 2022 NOPR. See
87 FR 42270.
DOE conducted an initial regulatory flexibility analysis (IRFA) as
part of the January 2022 NOPR and July 2022 SNOPR. See 87 FR 1554,
1590-1592 (Jan. 11, 2022); 87 FR 42270, 42285-42287 (July 14, 2022).
The following sections outline DOE's determination that this final rule
does not have a ``significant economic impact on a substantial number
of small entities,'' and that the preparation of a FRFA is not
warranted. DOE did not receive comment specific to the impacts on small
business manufacturers as part of the above-referenced IRFAs.
For manufacturers of consumer water heaters and residential-duty
commercial water heaters, the Small Business Administration (SBA) has
set a size threshold, which defines those entities classified as
``small businesses'' for the purposes of the statute. DOE used the
SBA's small business size standards to determine whether any small
entities would be subject to the requirements of the rule. (See 13 CFR
part 121.) The size standards are listed by North American Industry
Classification System (NAICS) code and industry description and are
available at: www.sba.gov/document/support--table-size-standards.
Manufacturing of consumer water heaters and residential-duty commercial
water heaters is classified under NAICS 335220, ``Major Household
Appliance Manufacturing.'' The SBA sets a threshold of 1,500 employees
or fewer for an entity to be considered as a small business for this
category. DOE used available public information to identify potential
small manufacturers. DOE accessed CCMS,\79\ the certified product
directory of the AHRI,\80\ company websites, and manufacturer
literature to identify companies that import, private label, or produce
the consumer water heaters and residential-duty commercial water
heaters covered by this rulemaking. Using these sources, DOE has
identified a total of 27 manufacturers of consumer water heaters and
residential-duty commercial water heaters.\81\ Of these 27
manufacturers, DOE identified one domestic small business that
manufactures products covered by the test procedure amendments.
---------------------------------------------------------------------------
\79\ U.S. Department of Energy Compliance Certification
Management System, available at: www.regulations.doe.gov/ccms. (Last
accessed July 19, 2022).
\80\ AHRI Directory of Certified Product Performance is
available at: www.ahridirectory.org/Search/SearchHome (Last accessed
July 19, 2022).
\81\ The January 2022 NOPR identified 31 manufacturers. 87 FR
1554, 1591 (Jan. 11, 2022). The July 2022 SNOPR identified 27
manufacturers. The changes reflect revisions based on manufacturer
feedback and additional public information.
---------------------------------------------------------------------------
More specifically, in the January 2022 NOPR IRFA, DOE evaluated a
range of potential test procedure amendments, with one amendment that
could lead to additional testing costs for small business. The existing
DOE test procedure does not accommodate testing of circulating water
heaters that require a separately sold hot water storage tank to
properly operate. In the January 2022 NOPR, DOE proposed to add
procedures to test such circulating water heaters to improve the
representativeness of the test procedure. The January 2022 NOPR
proposed testing be based on a commonly available 80-gallon unfired hot
water storage tank which minimally meets the energy conservation
standard requirements at 10 CFR 431.110(a). DOE estimated that the cost
of running the amended test procedure should be the same as testing a
comparable water heater with storage volume (i.e., third-party testing
of a fossil fuel-fired or electric storage water heater would cost
approximately $3,000; third-party testing of an electric storage water
heater which uses heat pump technology would cost approximately
$4,500). If a manufacturer chose to perform in-house testing rather
than use a third-party, the unfired hot water storage tank was stated
to be commercially available for approximately $900. The January 2022
IRFA identified one small manufacturer and estimated compliance costs
to be $4,500. 87 FR 1554, 1591 (Jan. 11, 2022).
The July 2022 SNOPR further updated DOE's proposal for testing
circulating water heaters that require a separately-sold hot water
storage tank to properly operate. Specifically, the July 2022 SNOPR
differentiated the test requirements for gas-fired circulating water
heaters and heat pump circulating water heaters. The July 2022 SNOPR
proposed that heat pump circulating water heaters be tested using an
electric storage water heaters that have a rated storage volume of 40
gallons 4 gallons, have an FHR that results in
classification at the medium draw pattern, and be rated at exactly the
minimum required UEF. Compared to the January 2022 NOPR, DOE revised
the requirements for circulating heat pump water heaters to better
reflect how heat pump water heaters may be installed in the field. To
determine cost of testing, DOE utilized a third-party test estimate of
$4,500. The July 2022 IRFA identified one small manufacturer and
estimated compliance costs to be $4,500. The proposal for heat pump
circulating water heaters was the only amendment in the July 2022 SNOPR
that could cause the small manufacturer to incur additional costs. 87
FR 42270, 42286-42287 (July 14, 2022).
In this final rule, DOE is establishing testing requirements
consistent with the proposal for heat pump circulating water heaters in
the July 2022 SNOPR, except that the acceptable volume range for the
separate tank has been expanded to 40 gallons 5 gallons.
For this final rule, DOE is aware of one domestic small manufacturer.
The small manufacturers has a single model (a circulating heat pump
water heater that requires a separately-sold hot water tank) that would
be affected by the amendments being adopted and that would need to be
re-tested. DOE estimates that testing would cost $4,500. If the
manufacturer conducts two rounds of physical testing, DOE expects the
cost impact on the small manufacturer to be $9,000, which is less than
0.01% of company revenue.
DOE has determined the cost impact to small businesses as result of
the amendments in this final rule to be minimal. DOE did not receive
any comments specifically pertaining to small business impacts.
Therefore, on the basis of the de minimis compliance burden, DOE
certifies that this test procedure final rule does not have a
``significant economic impact on a substantial number of small
entities,'' and that the preparation of a FRFA is not warranted. DOE
has submitted a certification and supporting statement of factual basis
to the Chief Counsel for Advocacy of the Small Business Administration
for review under 5 U.S.C. 605(b).
C. Review Under the Paperwork Reduction Act of 1995
Manufacturers of consumer water heaters and manufacturers of
residential-duty commercial water heaters must certify to DOE that
their products comply with any applicable energy conservation
standards. To certify compliance, manufacturers must first obtain test
data for their products according to the DOE test procedures, including
any amendments adopted for
[[Page 40470]]
those test procedures. DOE has established regulations for the
certification and recordkeeping requirements for all covered consumer
products and commercial equipment, including consumer water heaters and
residential-duty commercial water heaters. (See generally 10 CFR part
429.) The collection-of-information requirement for the certification
and recordkeeping is subject to review and approval by OMB under the
Paperwork Reduction Act (PRA). This requirement has been approved by
OMB under OMB control number 1910-1400. Public reporting burden for the
certification is estimated to average 35 hours per response, including
the time for reviewing instructions, searching existing data sources,
gathering and maintaining the data needed, and completing and reviewing
the collection of information.
DOE is not amending the certification or reporting requirements for
consumer water heaters and residential-duty commercial water heaters in
this final rule. Instead, DOE may consider proposals to amend the
certification requirements and reporting for these products and
equipment under a separate rulemaking regarding appliance and equipment
certification. DOE will address changes to OMB Control Number 1910-1400
at that time, as necessary.
Notwithstanding any other provision of the law, no person is
required to respond to, nor shall any person be subject to a penalty
for failure to comply with, a collection of information subject to the
requirements of the PRA, unless that collection of information displays
a currently valid OMB Control Number.
D. Review Under the National Environmental Policy Act of 1969
In this final rule, DOE amends the test procedure for consumer
water heaters and residential-duty commercial water heaters, amendments
which it expects will be used to develop and implement future energy
conservation standards for such products and equipment. DOE has
determined that this rule falls into a class of actions that are
categorically excluded from review under the National Environmental
Policy Act of 1969 (42 U.S.C. 4321 et seq.) and DOE's implementing
regulations at 10 CFR part 1021. Specifically, DOE has determined that
adopting test procedures for measuring energy efficiency of consumer
products and industrial equipment is consistent with activities
identified in 10 CFR part 1021, subpart D, appendix A, sections A5 and
A6. Accordingly, neither an environmental assessment nor an
environmental impact statement is required.
E. Review Under Executive Order 13132
Executive Order 13132, ``Federalism,'' 64 FR 43255 (August 1010,
1999), imposes certain requirements on agencies formulating and
implementing policies or regulations that preempt State law or that
have federalism implications. The Executive order requires agencies to
examine the constitutional and statutory authority supporting any
action that would limit the policymaking discretion of the States and
to carefully assess the necessity for such actions. The Executive order
also requires agencies to have an accountable process to ensure
meaningful and timely input by State and local officials in the
development of regulatory policies that have federalism implications.
On March 14, 2000, DOE published a statement of policy describing the
intergovernmental consultation process it will follow in the
development of such regulations. 65 FR 13735. DOE examined this final
rule and determined that it will not have a substantial direct effect
on the States, on the relationship between the national government and
the States, or on the distribution of power and responsibilities among
the various levels of government. EPCA governs and prescribes Federal
preemption of State regulations as to energy conservation for the
products and equipment that are the subject of this final rule. States
can petition DOE for exemption from such preemption to the extent, and
based on criteria, set forth in EPCA. (42 U.S.C. 6297(d)) No further
action is required by Executive Order 13132.
F. Review Under Executive Order 12988
Regarding the review of existing regulations and the promulgation
of new regulations, section 3(a) of Executive Order 12988, ``Civil
Justice Reform,'' 61 FR 4729 (Feb. 7, 1996), imposes on Federal
agencies the general duty to adhere to the following requirements: (1)
eliminate drafting errors and ambiguity; (2) write regulations to
minimize litigation; (3) provide a clear legal standard for affected
conduct rather than a general standard; and (4) promote simplification
and burden reduction. Section 3(b) of Executive Order 12988
specifically requires that Executive agencies make every reasonable
effort to ensure that the regulation: (1) clearly specifies the
preemptive effect, if any; (2) clearly specifies any effect on existing
Federal law or regulation; (3) provides a clear legal standard for
affected conduct while promoting simplification and burden reduction;
(4) specifies the retroactive effect, if any; (5) adequately defines
key terms; and (6) addresses other important issues affecting clarity
and general draftsmanship under any guidelines issued by the Attorney
General. Section 3(c) of Executive Order 12988 requires executive
agencies to review regulations in light of applicable standards in
sections 3(a) and 3(b) to determine whether they are met or it is
unreasonable to meet one or more of them. DOE has completed the
required review and determined that, to the extent permitted by law,
this final rule meets the relevant standards of Executive Order 12988.
G. Review Under the Unfunded Mandates Reform Act of 1995
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA)
requires each Federal agency to assess the effects of Federal
regulatory actions on State, local, and Tribal governments and the
private sector. Public Law 104-4, sec. 201 (codified at 2 U.S.C. 1531).
For a regulatory action resulting in a rule that may cause the
expenditure by State, local, and Tribal governments, in the aggregate,
or by the private sector of $100 million or more in any one year
(adjusted annually for inflation), section 202 of UMRA requires a
Federal agency to publish a written statement that estimates the
resulting costs, benefits, and other effects on the national economy.
(2 U.S.C. 1532(a), (b)) The UMRA also requires a Federal agency to
develop an effective process to permit timely input by elected officers
of State, local, and Tribal governments on a proposed ``significant
intergovernmental mandate,'' and requires an agency plan for giving
notice and opportunity for timely input to potentially affected small
governments before establishing any requirements that might
significantly or uniquely affect small governments. On March 18, 1997,
DOE published a statement of policy on its process for
intergovernmental consultation under UMRA. 62 FR 12820; also available
at www.energy.gov/gc/office-general-counsel. DOE examined this final
rule according to UMRA and its statement of policy and determined that
the rule contains neither an intergovernmental mandate, nor a mandate
that may result in the expenditure of $100 million or more in any year,
so these requirements do not apply.
H. Review Under the Treasury and General Government Appropriations Act,
1999
Section 654 of the Treasury and General Government Appropriations
[[Page 40471]]
Act, 1999 (Pub. L. 105-277) requires Federal agencies to issue a Family
Policymaking Assessment for any rule that may affect family well-being.
This final rule will not have any impact on the autonomy or integrity
of the family as an institution. Accordingly, DOE has concluded that it
is not necessary to prepare a Family Policymaking Assessment.
I. Review Under Executive Order 12630
DOE has determined, under Executive Order 12630, ``Governmental
Actions and Interference with Constitutionally Protected Property
Rights,'' 53 FR 8859 (March 18, 1988), that this regulation will not
result in any takings that might require compensation under the Fifth
Amendment to the U.S. Constitution.
J. Review Under Treasury and General Government Appropriations Act,
2001
Section 515 of the Treasury and General Government Appropriations
Act, 2001 (44 U.S.C. 3516 note) provides for agencies to review most
disseminations of information to the public under guidelines
established by each agency pursuant to general guidelines issued by
OMB. OMB's guidelines were published at 67 FR 8452 (Feb. 22, 2002), and
DOE's guidelines were published at 67 FR 62446 (Oct. 7, 2002). Pursuant
to OMB Memorandum M-19-15, Improving Implementation of the Information
Quality Act (April 24, 2019), DOE published updated guidelines which
are available at: www.energy.gov/sites/prod/files/2019/12/f70/DOE%20Final%20Updated%20IQA%20Guidelines%20Dec%202019.pdf. DOE has
reviewed this final rule under the OMB and DOE guidelines and has
concluded that it is consistent with applicable policies in those
guidelines.
K. Review Under Executive Order 13211
Executive Order 13211, ``Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use,'' 66 FR 28355
(May 22, 2001), requires Federal agencies to prepare and submit to OMB,
a Statement of Energy Effects for any significant energy action. A
``significant energy action'' is defined as any action by an agency
that promulgated or is expected to lead to promulgation of a final
rule, and that: (1) is a significant regulatory action under Executive
Order 12866, or any successor order; and (2) is likely to have a
significant adverse effect on the supply, distribution, or use of
energy; or (3) is designated by the Administrator of OIRA as a
significant energy action. For any significant energy action, the
agency must give a detailed statement of any adverse effects on energy
supply, distribution, or use if the regulation is implemented, and of
reasonable alternatives to the action and their expected benefits on
energy supply, distribution, and use.
This regulatory action is not a significant regulatory action under
Executive Order 12866. Moreover, it would not have a significant
adverse effect on the supply, distribution, or use of energy, nor has
it been designated as a significant energy action by the Administrator
of OIRA. Therefore, it is not a significant energy action, and,
accordingly, DOE has not prepared a Statement of Energy Effects.
L. Review Under Section 32 of the Federal Energy Administration Act of
1974
Under section 301 of the Department of Energy Organization Act
(Pub. L. 95-91; 42 U.S.C. 7101), DOE must comply with section 32 of the
Federal Energy Administration Act of 1974, as amended by the Federal
Energy Administration Authorization Act of 1977. (15 U.S.C. 788;
``FEAA'') Section 32 essentially provides in relevant part that, where
a proposed rule authorizes or requires use of commercial standards, the
notice of proposed rulemaking must inform the public of the use and
background of such standards. In addition, section 32(c) requires DOE
to consult with the Attorney General and the Chairman of the Federal
Trade Commission (FTC) concerning the impact of the commercial or
industry standards on competition.
The modifications to the Federal test procedure for consumer water
heaters and residential-duty commercial water heaters adopted in this
final rule incorporate testing methods contained in certain sections of
the following applicable commercial test standards: ASHRAE 41.1-2020,
ASTM D2156-09 (RA 2018), and ASHRAE 118.2-2022. DOE has evaluated these
standards and is unable to conclude whether they fully comply with the
requirements of section 32(b) of the FEAA (i.e., whether it was
developed in a manner that fully provides for public participation,
comment, and review.) DOE has consulted with both the Attorney General
and the Chairman of the FTC about the impact on competition of using
the methods contained in these standards and has received no comments
objecting to their use.
M. Congressional Notification
As required by 5 U.S.C. 801, DOE will report to Congress on the
promulgation of this rule before its effective date. The report will
state that it has been determined that the final rule is not a ``major
rule'' as defined by 5 U.S.C. 804(2).
N. Description of Materials Incorporated by Reference
In this final rule, DOE incorporates by reference the following
test standards:
ASHRAE 41.1-2020 prescribes methods for measuring temperature under
laboratory and field conditions which are required for system
performance tests and for testing heating, ventilating, air-
conditioning, and refrigerating components.
ASHRAE 41.6-2014 prescribes methods for measuring the humidity of
moist air with instruments.
ASHRAE 118.2-2022 provides test procedures for rating the
efficiency and hot water delivery capabilities of directly heated
residential water heaters and residential-duty commercial water
heaters.
ASTM D2156-09 (RA 2018) provides a test method to evaluate the
density of smoke in the flue gases from burning distillate fuels, which
is intended primarily for use with home heating equipment burning
kerosene or heating oils, and can be used in the laboratory or in the
field to compare fuels for clean burning or to compare heating
equipment.
ASTM E97-1987 (W1991) provides a method to determine the 45-deg, 0-
deg directional reflectance factor of nonfluorescent opaque specimens
by means of filter photometers.
Copies of ASHRAE 41.1-2020, ASHRAE 41.6-2014, and ASHRAE 118.2-2022
are reasonably available from the American Society of Heating,
Refrigerating, and Air-Conditioning Engineers, Inc., 180 Technology
Parkway NW, Peachtree Corners, GA 30092, (800) 527-4723 or (404) 636-
8400, or online at: www.ashrae.org.
Copies of ASTM D2156-09 (RA 2018) are reasonably available from
ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West
Conshohocken, PA 19428-2959 or online at: www.astm.org.
Copies of ASTM E97-1987 (W1991) are reasonably available from
standards resellers including GlobalSpec's Engineering 360 (https://standards.globalspec.com/std/3801495/astm-e97-82-1987) and IHS Markit
(https://global.ihs.com/doc_detail.cfm?document_name=ASTM%20E97&item_s_key=00020483).
V. Approval of the Office of the Secretary
The Secretary of Energy has approved publication of this final
rule.
[[Page 40472]]
List of Subjects
10 CFR Part 429
Administrative practice and procedure, Confidential business
information, Energy conservation, Household appliances, Imports,
Intergovernmental relations, Reporting and recordkeeping requirements,
Small businesses.
10 CFR Part 430
Administrative practice and procedure, Confidential business
information, Energy conservation, Household appliances, Imports,
Incorporation by reference, Intergovernmental relations, Reporting and
recordkeeping requirements, Small businesses.
10 CFR Part 431
Administrative practice and procedure, Confidential business
information, Energy conservation, Household appliances, Imports,
Intergovernmental relations, Laboratories, Reporting and recordkeeping
requirements, Small businesses.
Signing Authority
This document of the Department of Energy was signed on May 22,
2023, by Francisco Alejandro Moreno, Acting Assistant Secretary for
Energy Efficiency and Renewable Energy, pursuant to delegated authority
from the Secretary of Energy. That document with the original signature
and date is maintained by DOE. For administrative purposes only, and in
compliance with requirements of the Office of the Federal Register, the
undersigned DOE Federal Register Liaison Officer has been authorized to
sign and submit the document in electronic format for publication, as
an official document of the Department of Energy. This administrative
process in no way alters the legal effect of this document upon
publication in the Federal Register.
Signed in Washington, DC, on May 24, 2023.
Treena V. Garrett,
Federal Register Liaison Officer, U.S. Department of Energy.
For the reasons stated in the preamble, DOE amends parts 429, 430,
and 431 of Chapter II of Title 10, Code of Federal Regulations, as set
forth below:
PART 429--CERTIFICATION, COMPLIANCE, AND ENFORCEMENT FOR CONSUMER
PRODUCTS AND COMMERCIAL AND INDUSTRIAL EQUIPMENT
0
1. The authority citation for part 429 continues to read as follows:
Authority: 42 U.S.C. 6291-6317; 28 U.S.C. 2461 note.
0
2. Amend Sec. 429.70 by revising paragraph (g)(2) and adding paragraph
(g)(3) to read as follows:
Sec. 429.70 Alternative methods for determining energy efficiency and
energy use.
* * * * *
(g) * * *
(2) Electric Storage Water Heaters. Rate an untested basic model of
an electric storage-type water heater using the first-hour rating or
maximum GPM (whichever is applicable under section 5.3.1 of appendix E
to subpart B of this part) and uniform energy factor obtained from a
tested basic model as the basis for ratings of basic models with other
input ratings, provided that certain conditions are met:
(i) For an untested basic model, the represented value of the
first-hour rating or maximum GPM and the uniform energy factor is the
same as that of a tested basic model, provided that each heating
element of the untested basic model is rated at or above the input
rating for the corresponding heating element of the tested basic model.
(ii) For an untested basic model having any heating element with an
input rating that is lower than that of the corresponding heating
element in the tested basic model, the represented value of the first-
hour rating or maximum GPM and the uniform energy factor is the same as
that of a tested basic model, provided that the first-hour rating for
the untested basic model results in the same draw pattern specified in
Table I of appendix E for the simulated-use test as was applied to the
tested basic model. To establish whether this condition is met,
determine the first-hour ratings or maximum GPMs for the tested and the
untested basic models in accordance with the procedure described in
section 5.3 of 10 CFR part 430, subpart B, appendix E, then compare the
appropriate draw pattern specified in Table I of appendix E for the
first-hour rating of the tested basic model with that for the untested
basic model. If this condition is not met, then the untested basic
model must be tested, and the appropriate sampling provisions must be
applied to determine its uniform energy factor in accordance with
appendix E and this part.
(3) Electric Instantaneous Water Heaters. Rate an untested basic
model of an electric instantaneous-type water heater using the first-
hour rating or maximum GPM and the uniform energy factor obtained from
a tested basic model as a basis for ratings of basic models with other
input ratings, provided that certain conditions are met:
(i) For an untested basic model, the represented value of the
first-hour rating or maximum GPM and the uniform energy factor is the
same as that of a tested basic model, provided that the untested basic
model's input is rated at or above the input rating for the
corresponding tested basic model.
(ii) For an untested basic model having an input rating that is
lower than that of the corresponding tested basic model, the
represented value of the first-hour rating or maximum GPM and the
uniform energy factor is the same as that of a tested basic model,
provided that the first-hour rating or maximum GPM for the untested
basic model results in the same draw pattern specified in Table II of
appendix E for the 24-hour simulated-use test as was applied to the
tested basic model. To establish whether this condition is met,
determine the first-hour rating or maximum GPM for the tested and the
untested basic models in accordance with the procedure described in
section 5.3 of 10 CFR part 430, subpart B, appendix E, then compare the
appropriate draw pattern specified in Table II of appendix E for the
first-hour rating or maximum GPM of the tested basic model with that
for the untested basic model. If this condition is not met, then the
untested basic model must be tested, and the appropriate sampling
provisions must be applied to determine its uniform energy factor in
accordance with appendix E and this part.
* * * * *
0
3. Amend Sec. 429.134 by adding paragraph (d)(3) to read as follows:
Sec. 429.134 Product-specific enforcement provisions.
* * * * *
(d) * * *
(3) Verification of fuel input rate. The fuel input rate of each
tested unit of the basic model will be measured pursuant to the test
requirements of section 5.2.3 of 10 CFR part 430, subpart B, appendix
E. The measured fuel input rate (either the measured fuel input rate
for a single unit sample or the average of the measured fuel input
rates for a multiple unit sample) will be compared to the rated input
certified by the
[[Page 40473]]
manufacturer. The certified rated input will be considered valid only
if the measured fuel input rate is within 2 percent of the
certified rated input.
(i) If the certified rated input is found to be valid, then the
certified rated input will be used to determine compliance with the
associated energy conservation standard.
(ii) If the measured fuel input rate for gas-fired or oil-fired
water heating products is not within 2 percent of the
certified rated input, the measured fuel input rate will be used to
determine compliance with the associated energy conservation standard.
* * * * *
PART 430--ENERGY CONSERVATION PROGRAM FOR CONSUMER PRODUCTS
0
4. The authority citation for part 430 continues to read as follows:
Authority: 42 U.S.C. 6291-6309; 28 U.S.C. 2461 note.
0
5. Amend Sec. 430.2 by adding in alphabetical order definitions for
``Circulating water heater'', ``Low-temperature water heater'', and
``Tabletop water heater'' to read as follows:
Sec. 430.2 Definitions.
* * * * *
Circulating water heater means an instantaneous or heat pump-type
water heater that does not have an operational scheme in which the
burner, heating element, or compressor initiates and/or terminates
heating based on sensing flow; has a water temperature sensor located
at the inlet or the outlet of the water heater or in a separate storage
tank that is the primary means of initiating and terminating heating;
and must be used in combination with a recirculating pump and either a
separate storage tank or water circulation loop in order to achieve the
water flow and temperature conditions recommended in the manufacturer's
installation and operation instructions.
* * * * *
Low-temperature water heater means an electric instantaneous water
heater that is not a circulating water heater and cannot deliver water
at a temperature greater than or equal to the set point temperature
specified in section 2.5 of appendix E to subpart B of this part when
supplied with water at the supply water temperature specified in
section 2.3 of appendix E to subpart B of this part and the flow rate
specified in section 5.2.2.1 of appendix E to subpart B of this part.
* * * * *
Tabletop water heater means a heater in a rectangular box enclosure
designed to slide into a kitchen countertop space with typical
dimensions of 36 inches high, 25 inches deep, and 24 inches wide.
* * * * *
0
6. Section 430.3 is amended by:
0
a. In paragraph (g)(5), removing the text ``appendices E, AA'' and
adding, in its place, the text ``appendices AA'';
0
b. Redesignating paragraph (g)(20) as paragraph (g)(22);
0
c. Redesignating paragraph (g)(8) through (19) as paragraphs (g)(9)
through (20);
0
d. Adding new paragraph (g)(8);
0
e. In newly redesignated paragraph (g)(13), removing the text ``F and
EE'' and adding, in its place, the text ``E, F, and EE'';
0
f. Adding new paragraph (g)(21);
0
g. Revising paragraph (j).
The revisions and additions read as follows:
Sec. 430.3 Materials incorporated by reference.
* * * * *
(g) * * *
(8) ANSI/ASHRAE Standard 41.1-2020 (``ASHRAE 41.1-2020''), Standard
Methods for Temperature Measurement, ANSI-approved June 30, 2020; IBR
approved for appendix E to subpart B.
* * * * *
(21) ANSI/ASHRAE Standard 118.2-2022 (``ASHRAE 118.2-2022''),
Method of Testing for Rating Residential Water Heaters and Residential-
Duty Commercial Water Heaters, ANSI-approved March 1, 2022; IBR
approved for appendix E to subpart B.
* * * * *
(j) ASTM. ASTM International, 100 Barr Harbor Drive, P.O. Box C700,
West Conshohocken, PA 19428-2959; 877-909-2786; [email protected];
www.astm.org.
(1) ASTM D2156-09 (Reapproved 2013) (``ASTM D2156R13''), Standard
Test Method for Smoke Density in Flue Gases from Burning Distillate
Fuels, approved October 1, 2013; IBR approved for appendix N to subpart
B.
(2) ASTM D2156-09 (Reapproved 2018) (``ASTM D2156 (R2018)''),
Standard Test Method for Smoke Density in Flue Gases from Burning
Distillate Fuels, approved October 1, 2018; IBR approved for appendices
E, O, and EE to subpart B.
(3) ASTM E97-82 (Reapproved 1987) (``ASTM E97-1987''), Standard
Test Method for Directional Reflectance Factor, 45-deg 0-deg, of Opaque
Specimens by Broad-Band Filter Reflectometry, ASTM-approved October 29,
1982; IBR approved for appendix E to subpart B.
Note 2 to paragraph (j)(3): ASTM E97-1987 was withdrawn in 1991.
It is reasonably available from standards resellers including
GlobalSpec's Engineering 360 (https://standards.globalspec.com/std/3801495/astm-e97-82-1987) and IHS Markit (https://global.ihs.com/doc_detail.cfm?document_name=ASTM%20E97&item_s_key=00020483).
(4) ASTM E741-11 (Reapproved 2017) (``ASTM E741-11(2017)''),
Standard Test Method for Determining Air Change in a Single Zone Means
of a Tracer Gas Dilution Approved Sept. 1, 2017; IBR approved for
appendix FF to subpart B.
* * * * *
0
7. Appendix E to subpart B of part 430 is revised to read as follows:
Appendix E to Subpart B of Part 430--Uniform Test Method for Measuring
the Energy Consumption of Water Heaters
Note: Prior to December 18, 2023, representations with respect
to the energy use or efficiency of consumer water heaters covered by
this test method, including compliance certifications, must be based
on testing conducted in accordance with either this appendix as it
now appears or appendix E as it appeared at 10 CFR part 430, subpart
B revised as of January 1, 2021.
On and after December 18, 2023, representations with respect to
energy use or efficiency of consumer water heaters covered by this
test method, including compliance certifications, must be based on
testing conducted in accordance with this appendix, except as
outlined in the following paragraphs.
Prior to June 17, 2024, representations with respect to the
energy use or efficiency of residential-duty commercial water
heaters covered by this test method, including compliance
certifications, must be based on testing conducted in accordance
with either this appendix as it now appears or appendix E as it
appeared at 10 CFR part 430, subpart B revised as of January 1,
2021.
On and after June 17, 2024, representations with respect to
energy use or efficiency of residential-duty commercial water
heaters covered by this test method, including compliance
certifications, must be based on testing conducted in accordance
with this appendix.
Water heaters subject to section 4.10 of this appendix may
optionally apply the requirements in section 4.10 of this appendix
prior to the compliance date of a final rule reviewing potential
amended energy conservation standards for these products and
equipment published after June 21, 2023. After the compliance date
of such standards final rule, the requirements of section 4.10 are
mandatory.
In addition, certain electric resistance storage water heaters
may optionally apply the requirements in section 5.1.2 of this
appendix in lieu of the requirements in section 5.1.1 of this
appendix for additional
[[Page 40474]]
voluntary representations only. Water heaters must certify according
to the requirements in section 5.1.1 until the publication of a
final rule reviewing potential amended energy conservation standards
and specifying the required use of section 5.1.2 for these products
published after June 21, 2023.
0. Incorporation by Reference.
DOE incorporated by reference in Sec. 430.3 the entire standard
for: ASHRAE 41.1-2020; ASHRAE 41.6-2014; ASHRAE 118.2-2022; ASTM
D2156-09 (R2018); and ASTM E97-1987. However, only enumerated
provisions of ASHRAE 118.2-2022 are applicable to this appendix, as
follows:
0.1 ASHRAE 118.2-2022
(a) Annex B--Gas Heating Value Correction Factor;
(b) [Reserved]
0.2 [Reserved]
1. Definitions.
1.1. Cut-in means the time when or water temperature at which a
water heater control or thermostat acts to increase the energy or
fuel input to the heating elements, compressor, or burner.
1.2. Cut-out means the time when or water temperature at which a
water heater control or thermostat acts to reduce to a minimum the
energy or fuel input to the heating elements, compressor, or burner.
1.3. Design Power Rating means the power rating or input rate
that a water heater manufacturer assigns to a particular design of
water heater and that is included on the nameplate of the water
heater, expressed in kilowatts or Btu (kJ) per hour as appropriate.
For modulating water heaters, the design power rating is the maximum
power rating or input rate that is specified by the manufacturer on
the nameplate of the water heater.
1.4. Draw Cluster means a collection of water draws initiated
during the 24-hour simulated-use test during which no successive
draws are separated by more than 2 hours.
1.5. First-Hour Rating means an estimate of the maximum volume
of ``hot'' water that a non-flow activated water heater can supply
within an hour that begins with the water heater fully heated (i.e.,
with all thermostats satisfied).
1.6. Flow-Activated describes an operational scheme in which a
water heater initiates and terminates heating based on sensing flow.
1.7. Heat Trap means a device that can be integrally connected
or independently attached to the hot and/or cold water pipe
connections of a water heater such that the device will develop a
thermal or mechanical seal to minimize the recirculation of water
due to thermal convection between the water heater tank and its
connecting pipes.
1.8. Maximum GPM (L/min) Rating means the maximum gallons per
minute (liters per minute) of hot water that can be supplied by a
flow-activated water heater when tested in accordance with section
5.3.2 of this appendix.
1.9. Modulating Water Heater means a water heater that can
automatically vary its power or input rate from the minimum to the
maximum power or input rate specified on the nameplate of the water
heater by the manufacturer.
1.10. Rated Storage Volume means the water storage capacity of a
water heater, in gallons (liters), as certified by the manufacturer
pursuant to 10 CFR part 429.
1.11. Recovery Efficiency means the ratio of energy delivered to
the water to the energy content of the fuel consumed by the water
heater.
1.12. Recovery Period means the time when the main burner of a
water heater with a rated storage volume greater than or equal to 2
gallons is raising the temperature of the stored water.
1.13. Split-system heat pump water heater means a heat pump-type
water heater in which at least the compressor, which may be
installed outdoors, is separate from the storage tank.
1.14. Standby means the time, in hours, during which water is
not being withdrawn from the water heater.
1.15. Symbol Usage. The following identity relationships are
provided to help clarify the symbology used throughout this
procedure:
Cp--specific heat of water
Eannual--annual energy consumption of a water heater
Eannual,e--annual electrical energy consumption of a
water heater
Eannual,f--annual fossil-fuel energy consumption of a
water heater
EX--energy efficiency of a heat pump-type water heater
when the 24-hour simulated use test is optionally conducted at any
of the additional air temperature conditions as specified in section
2.8 of this appendix, where the subscript ``X'' corresponds to the
dry-bulb temperature at which the test is conducted.
Fhr--first-hour rating of a non-flow activated water
heater
Fmax--maximum GPM (L/min) rating of a flow-activated
water heater
i--a subscript to indicate the draw number during a test
kV--storage tank volume scaling ratio for water heaters
with a rated storage volume greater than or equal to 2 gallons
Mdel,i--mass of water removed during the ith draw of the
24-hour simulated-use test
Min,i--mass of water entering the water heater during the
ith draw of the 24-hour simulated-use test
M*del,i--for non-flow activated water heaters, mass of
water removed during the ith draw during the first-hour rating test
M*in,i--for non-flow activated water heaters, mass of
water entering the water heater during the ith draw during the
first-hour rating test
Mdel,10m--for flow-activated water heaters, mass of water
removed continuously during the maximum GPM (L/min) rating test
Min,10m--for flow-activated water heaters, mass of water
entering the water heater continuously during the maximum GPM (L/
min) rating test
n--for non-flow activated water heaters, total number of draws
during the first-hour rating test
N--total number of draws during the 24-hour simulated-use test
Nr--number of draws from the start of the 24-hour
simulated-use test to the end to the first recovery period as
described in section 5.4.2 of this appendix
Q--total fossil fuel and/or electric energy consumed during the
entire 24-hour simulated-use test
Qd--daily water heating energy consumption adjusted for
net change in internal energy
Qda--Qd with adjustment for variation of tank
to ambient air temperature difference from nominal value
Qdm--overall adjusted daily water heating energy
consumption including Qda and QHWD
Qe--total electrical energy used during the 24-hour
simulated-use test
Qf--total fossil fuel energy used by the water heater
during the 24-hour simulated-use test
Qhr--hourly standby losses of a water heater with a rated
storage volume greater than or equal to 2 gallons
QHW--daily energy consumption to heat water at the
measured average temperature rise across the water heater
QHW,67 [deg]F--daily energy consumption to heat quantity
of water removed during test over a temperature rise of 67 [deg]F
(37.3 [deg]C)
QHWD--adjustment to daily energy consumption,
QHW, due to variation of the temperature rise across the
water heater not equal to the nominal value of 67 [deg]F (37.3
[deg]C)
Qr--energy consumption of water heater from the beginning
of the test to the end of the first recovery period
Qstby--total energy consumed during the standby time
interval [tau]stby,1, as determined in section 5.4.2 of
this appendix
Qsu,0--cumulative energy consumption, including all
fossil fuel and electrical energy use, of the water heater from the
start of the 24-hour simulated-use test to the start of the standby
period as determined in section 5.4.2 of this appendix
Qsu,f--cumulative energy consumption, including all
fossil fuel and electrical energy use, of the water heater from the
start of the 24-hour simulated-use test to the end of the standby
period as determined in section 5.4.2 of this appendix
T0--mean tank temperature at the beginning of the 24-hour
simulated-use test as determined in section 5.4.2 of this appendix
T24--mean tank temperature at the end of the 24-hour
simulated-use test as determined in section 5.4.2 of this appendix
Ta,stby--average ambient air temperature during all
standby periods of the 24-hour simulated-use test as determined in
section 5.4.2 of this appendix
Ta,stby,1--overall average ambient temperature between
the start and end of the standby period as determined in section
5.4.2 of this appendix
Tt,stby,1-- overall average mean tank temperature between
the start and end of the standby period as determined in section
5.4.2 of this appendix
Tdel--for flow-activated water heaters, average outlet
water temperature during the maximum GPM (L/min) rating test
Tdel,i--average outlet water temperature during the ith
draw of the 24-hour simulated-use test
[[Page 40475]]
Tin--for flow-activated water heaters, average inlet
water temperature during the maximum GPM (L/min) rating test
Tst--for water heaters which cannot have internal tank
temperature directly measured, estimated average internal storage
tank temperature
Tp--for water heaters which cannot have internal tank
temperature directly measured, average of the inlet and the outlet
water temperatures at the end of the period defined by
[tau]p
Tin,p--for water heaters which cannot have internal tank
temperature directly measured, average of the inlet water
temperatures
Tout,p--for water heaters which cannot have internal tank
temperature directly measured, average of the outlet water
temperatures
Tin,i--average inlet water temperature during the ith
draw of the 24-hour simulated-use test
Tmax,1--maximum measured mean tank temperature after the
first recovery period of the 24-hour simulated-use test as
determined in section 5.4.2 of this appendix
Tsu,0--maximum measured mean tank temperature at the
beginning of the standby period as determined in section 5.4.2 of
this appendix
Tsu,f--measured mean tank temperature at the end of the
standby period as determined in section 5.4.2 of this appendix
T*del,i--for non-flow activated water heaters, average
outlet water temperature during the ith draw (i = 1 to n) of the
first-hour rating test
T*max,i--for non-flow activated water heaters, maximum
outlet water temperature observed during the ith draw (i = 1 to n)
of the first-hour rating test
T*min,i--for non-flow activated water heaters, minimum
outlet water temperature to terminate the ith draw (i = 1 to n) of
the first-hour rating test
UA--standby loss coefficient of a water heater with a rated storage
volume greater than or equal to 2 gallons
UEF--uniform energy factor of a water heater
V--the volume of hot water drawn during the applicable draw pattern
Vdel,i--volume of water removed during the ith draw (i =
1 to N) of the 24-hour simulated-use test
Vin,i--volume of water entering the water heater during
the ith draw (i = 1 to N) of the 24-hour simulated-use test
V*del,i--for non-flow activated water heaters, volume of
water removed during the ith draw (i = 1 to n) of the first-hour
rating test
V*in,i--for non-flow activated water heaters, volume of
water entering the water heater during the ith draw (i = 1 to n) of
the first-hour rating test
Vdel,10m--for flow-activated water heaters, volume of
water removed during the maximum GPM (L/min) rating test
Vin,10m--for flow-activated water heaters, volume of water entering
the water heater during the maximum GPM (L/min) rating test
Vst--measured storage volume of the storage tank for water heaters
with a rated storage volume greater than or equal to 2 gallons
Veff--effective storage volume
vout,p--for water heaters which cannot have internal tank
temperature directly measured, average flow rate
Wf--weight of storage tank when completely filled with water for
water heaters with a rated storage volume greater than or equal to 2
gallons
Wt--tare weight of storage tank when completely empty of water for
water heaters with a rated storage volume greater than or equal to 2
gallons
[eta]r--recovery efficiency
[rho]--density of water
[tau]p--for water heaters which cannot have internal tank
temperature directly measured, duration of the temperature
measurement period, determined by the length of time taken for the
outlet water temperature to be within 2 [deg]F of the inlet water
temperature for 15 consecutive seconds (including the 15-second
stabilization period)
[tau]stby,1--elapsed time between the start and end of the standby
period as determined in section 5.4.2 of this appendix
[tau]stby,2--overall time of standby periods when no water is
withdrawn during the 24-hour simulated-use test as determined in
section 5.4.2 of this appendix
1.16. Temperature Controller means a device that is available to
the user to adjust the temperature of the water inside a water
heater that stores heated water or the outlet water temperature.
1.17. Thermal break means a thermally non-conductive material
that can withstand a pressure of 150 psi (1.034 MPa) at a
temperature greater than the maximum temperature the water heater is
designed to produce and is utilized to insulate a bypass loop, if
one is used in the test set-up, from the inlet piping.
1.18. Uniform Energy Factor means the measure of water heater
overall efficiency.
1.19. Water Heater Requiring a Storage Tank means a water heater
without a storage tank specified or supplied by the manufacturer
that cannot meet the requirements of sections 2 and 5 of this
appendix without the use of a storage water heater or unfired hot
water storage tank.
2. Test Conditions.
2.1 Installation Requirements. Tests shall be performed with the
water heater and instrumentation installed in accordance with
section 4 of this appendix.
2.2 Ambient Air Temperature and Relative Humidity.
2.2.1 Non-Heat Pump Water Heaters. The ambient air temperature
shall be maintained between 65.0 [deg]F and 70.0 [deg]F (18.3 [deg]C
and 21.1 [deg]C) on a continuous basis.
2.2.2 Heat Pump Water Heaters. The dry-bulb temperature shall be
maintained at an average of 67.5 [deg]F 1 [deg]F (19.7
[deg]C 0.6 [deg]C) after a cut-in and before the next
cut-out, an average of 67.5 [deg]F 2.5 [deg]F (19.7
[deg]C 1.4 [deg]C) after a cut-out and before the next
cut-in, and at 67.5 [deg]F 5 [deg]F (19.7 [deg]C 2.8 [deg]C) on a continuous basis throughout the test. The
relative humidity shall be maintained within a range of 50% 5% throughout the test, and at an average of 50%
2% after a cut-in and before the next cut-out.
When testing a split-system heat pump water heater or heat pump
water heater requiring a separate storage tank, the heat pump
portion of the system shall be tested at the conditions within this
section and the separate water heater or unfired hot water storage
tank shall be tested at either the conditions within this section or
the conditions specified in section 2.2.1 of this appendix.
2.3 Supply Water Temperature. The temperature of the water being
supplied to the water heater shall be maintained at 58 [deg]F 2 [deg]F (14.4 [deg]C 1.1 [deg]C) throughout the
test.
2.4 Outlet Water Temperature. The temperature controllers of a
non-flow activated water heater shall be set so that water is
delivered at a temperature of 125 [deg]F 5 [deg]F (51.7
[deg]C 2.8 [deg]C).
2.5 Set Point Temperature. The temperature controller of a flow-
activated water heater shall be set to deliver water at a
temperature of 125 [deg]F 5 [deg]F (51.7 [deg]C 2.8 [deg]C). If the flow-activated water heater is not
capable of delivering water at a temperature of 125 [deg]F 5 [deg]F (51.7 [deg]C 2.8 [deg]C) when supplied
with water at the supply water temperature specified in section 2.3
of this appendix, then the flow-activated water heater shall be set
to deliver water at its maximum water temperature.
2.6 Supply Water Pressure. During the test when water is not
being withdrawn, the supply pressure shall be maintained between 40
psig (275 kPa) and the maximum allowable pressure specified by the
water heater manufacturer.
2.7 Electrical and/or Fossil Fuel Supply.
2.7.1 Electrical. Maintain the electrical supply voltage to
within 2% of the center of the voltage range specified
on the nameplate of the water heater by the water heater and/or heat
pump manufacturer, from 5 seconds after a cut-in to 5 seconds before
next cut-out.
2.7.2 Natural Gas. Maintain the supply pressure in accordance
with the supply pressure specified on the nameplate of the water
heater by the manufacturer. If the supply pressure is not specified,
maintain a supply pressure of 7-10 inches of water column (1.7-2.5
kPa). If the water heater is equipped with a gas appliance pressure
regulator and the gas appliance pressure regulator can be adjusted,
the regulator outlet pressure shall be within the greater of 10% of the manufacturer's specified manifold pressure, found
on the nameplate of the water heater, or 0.2 inches
water column (0.05 kPa). Maintain the gas supply pressure and
manifold pressure only when operating at the design power rating.
For all tests, use natural gas having a heating value of
approximately 1,025 Btu per standard cubic foot (38,190 kJ per
standard cubic meter).
2.7.3 Propane Gas. Maintain the supply pressure in accordance
with the supply pressure specified on the nameplate of the water
heater by the manufacturer. If the supply pressure is not specified,
maintain a supply pressure of 11-13 inches of water column (2.7-3.2
kPa). If the water heater is equipped with a gas appliance pressure
regulator and the gas appliance pressure regulator can be adjusted,
the regulator outlet pressure shall be within the greater of 10% of the manufacturer's specified manifold pressure, found
on the nameplate of the
[[Page 40476]]
water heater, or 0.2 inches water column (0.05 kPa).
Maintain the gas supply pressure and manifold pressure only when
operating at the design power rating. For all tests, use propane gas
with a heating value of approximately 2,500 Btu per standard cubic
foot (93,147 kJ per standard cubic meter).
2.7.4 Fuel Oil Supply. Maintain an uninterrupted supply of fuel
oil. The fuel pump pressure shall be within 10% of the
pump pressure specified on the nameplate of the water heater or the
installation and operations (I&O) manual by the manufacturer. Use
fuel oil having a heating value of approximately 138,700 Btu per
gallon (38,660 kJ per liter).
2.8 Optional Test Conditions (Heat Pump-Type Water Heaters). The
following test conditions may be used for optional representations
of EX for heat pump-type water heaters. When conducting a
24-hour simulated use test to determine EX, the test
conditions in section 2.1 and sections 2.4 through 2.7 apply. The
ambient air temperature and humidity conditions in section 2.2 and
the supply water temperature in section 2.3 are replaced with the
air temperature, humidity, and supply water temperature conditions
as shown in the following table. Testing may optionally be performed
at any or all of the conditions in the table, and the sampling plan
found at 10 CFR 429.17(a) may be applied for voluntary
representations.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Outdoor air conditions Indoor air conditions
---------------------------------------------------------------- Supply water
Heat pump type Metric Dry-bulb Dry-bulb temperature
temperature Relative temperature Relative ([deg]F)
([deg]F) humidity (%) ([deg]F) humidity (%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Split-System or Circulating................. E5 5.0 30 67.5 50 42.0
E34 34.0 72 .............. .............. 47.0
E95 95.0 25 .............. .............. 67.0
Integrated, Split-System, or Circulating.... E50 N/A N/A 50.0 58 50.0
E95 N/A N/A 95.0 40 67.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
3. Instrumentation.
3.1 Pressure Measurements. Pressure-measuring instruments shall
have an error no greater than the following values:
------------------------------------------------------------------------
Instrument Instrument
Item measured accuracy precision
------------------------------------------------------------------------
Gas pressure.................... 0.1 0.05
inch of water inch of water
column (0.025 kPa). minus>0.012 kPa).
Atmospheric pressure............ 0.1 0.05
inch of mercury inch of mercury
column (0.34 kPa). minus>0.17 kPa).
Water pressure.................. 1.0 0.50
pounds per square pounds per square
inch (6.9 kPa). minus>3.45 kPa).
------------------------------------------------------------------------
3.2 Temperature Measurement
3.2.1 Measurement. Temperature measurements shall be made in
accordance with the Standard Method for Temperature Measurement,
ASHRAE 41.1-2020, including the conditions as specified in ASHRAE
41.6-2014 as referenced in ASHRAE 41.1-2020, and excluding the
steady-state temperature criteria in section 5.5 of ASHRAE 41.1-
2020.
3.2.2 Accuracy and Precision. The accuracy and precision of the
instruments, including their associated readout devices, shall be
within the following limits:
------------------------------------------------------------------------
Instrument Instrument
Item measured accuracy precision
------------------------------------------------------------------------
Air dry-bulb temperature........ 0.2 0.1
[deg]F (0.1 [deg]C). minus>0.06
[deg]C).
Air wet-bulb temperature........ 0.2 0.1
[deg]F (0.1 [deg]C). minus>0.06
[deg]C).
Inlet and outlet water 0.2 0.1
temperatures. [deg]F (0.1 [deg]C). minus>0.06
[deg]C).
Storage tank temperatures....... 0.5 0.25
[deg]F (0.3 [deg]C). minus>0.14
[deg]C).
------------------------------------------------------------------------
3.2.3 Scale Division. In no case shall the smallest scale
division of the instrument or instrument system exceed 2 times the
specified precision.
3.2.4 Temperature Difference. Temperature difference between the
entering and leaving water may be measured with any of the
following:
(a) A thermopile
(b) Calibrated resistance thermometers
(c) Precision thermometers
(d) Calibrated thermistors
(e) Calibrated thermocouples
(f) Quartz thermometers
3.2.5 Thermopile Construction. If a thermopile is used, it shall
be made from calibrated thermocouple wire taken from a single spool.
Extension wires to the recording device shall also be made from that
same spool.
3.2.6 Time Constant. The time constant of the instruments used
to measure the inlet and outlet water temperatures shall be no
greater than 2 seconds.
3.3 Liquid Flow Rate Measurement. The accuracy of the liquid
flow rate measurement, using the calibration if furnished, shall be
equal to or less than 1% of the measured value in mass
units per unit time.
3.4 Electrical Energy. The electrical energy used shall be
measured with an instrument and associated readout device that is
accurate within 0.5% of the reading.
3.5 Fossil Fuels. The quantity of fuel used by the water heater
shall be measured with an instrument and associated readout device
that is accurate within 1% of the reading.
3.6 Mass Measurements. For mass measurements greater than or
equal to 10 pounds (4.5 kg), a scale that is accurate within 0.5% of the reading shall be used to make the measurement. For
mass measurements less than 10 pounds (4.5 kg), the scale shall
provide a measurement that is accurate within 0.1 pound
(0.045 kg).
3.7 Heating Value. The higher heating value of the natural gas,
propane, or fuel oil shall be measured with an instrument and
associated readout device that is accurate within 1% of
the reading. The heating values of natural gas and propane must be
corrected from those measured to the standard temperature of 60.0
[deg]F (15.6 [deg]C) and standard pressure of 30 inches of mercury
column (101.6 kPa) using the method described in Annex B of ASHRAE
118.2-2022.
3.8 Time. The elapsed time measurements shall be measured with
an instrument that is accurate within 0.5 seconds per
hour.
3.9 Volume. Volume measurements shall be measured with an
accuracy of 2% of the total volume.
3.10 Relative Humidity. If a relative humidity (RH) transducer
is used to measure the relative humidity of the surrounding air
while testing heat pump water heaters, the
[[Page 40477]]
relative humidity shall be measured with an accuracy of 1.5% RH.
4. Installation.
4.1 Water Heater Mounting. A water heater designed to be
freestanding shall be placed on a \3/4\ inch (2 cm) thick plywood
platform supported by three 2x4 inch (5 cm x 10 cm) runners. If the
water heater is not approved for installation on combustible
flooring, suitable non-combustible material shall be placed between
the water heater and the platform. Water heaters designed to be
installed into a kitchen countertop space shall be placed against a
simulated wall section. Wall-mounted water heaters shall be
supported on a simulated wall in accordance with the manufacturer-
published installation instructions. When a simulated wall is used,
the construction shall be 2x4 inch (5 cm x 10 cm) studs, faced with
\3/4\ inch (2 cm) plywood. For heat pump water heaters not delivered
as a single package, the units shall be connected in accordance with
the manufacturer-published installation instructions, and the
overall system shall be placed on the above-described plywood
platform. If installation instructions are not provided by the heat
pump manufacturer, uninsulated 8 foot (2.4 m) long connecting hoses
having an inside diameter of \5/8\ inch (1.6 cm) shall be used to
connect the storage tank and the heat pump water heater. With the
exception of using the storage tank described in section 4.10 of
this appendix, the same requirements shall apply for water heaters
requiring a storage tank. The testing of the water heater shall
occur in an area that is protected from drafts of more than 50 ft/
min (0.25 m/s) from room ventilation registers, windows, or other
external sources of air movement.
4.2 Water Supply. Connect the water heater to a water supply
capable of delivering water at conditions as specified in sections
2.3 and 2.6 of this appendix.
4.3 Water Inlet and Outlet Configuration. For freestanding water
heaters that are taller than 36 inches (91.4 cm), inlet and outlet
piping connections shall be configured in a manner consistent with
Figures 1 and 2 of section 7 of this appendix. Inlet and outlet
piping connections for wall-mounted water heaters shall be
consistent with Figure 3 of section 7 of this appendix. For
freestanding water heaters that are 36 inches or less in height and
not supplied as part of a counter-top enclosure (commonly referred
to as an under-the-counter model), inlet and outlet piping shall be
installed in a manner consistent with Figures 4, 5, or 6 of section
7 of this appendix. For water heaters that are supplied with a
counter-top enclosure, inlet and outlet piping shall be made in a
manner consistent with Figures 7a and 7b of section 7 of this
appendix, respectively. The vertical piping noted in Figures 7a and
7b shall be located (whether inside the enclosure or along the
outside in a recessed channel) in accordance with the manufacturer-
published installation instructions.
All dimensions noted in Figures 1 through 7 of section 7 of this
appendix must be achieved. All piping between the water heater and
inlet and outlet temperature sensors, noted as TIN and
TOUT in the figures, shall be Type ``L'' hard copper
having the same diameter as the connections on the water heater.
Unions may be used to facilitate installation and removal of the
piping arrangements. Install a pressure gauge and diaphragm
expansion tank in the supply water piping at a location upstream of
the inlet temperature sensor. Install an appropriately rated
pressure and temperature relief valve on all water heaters at the
port specified by the manufacturer. Discharge piping for the relief
valve must be non-metallic. If heat traps, piping insulation, or
pressure relief valve insulation are supplied with the water heater,
they must be installed for testing. Except when using a simulated
wall, provide sufficient clearance such that none of the piping
contacts other surfaces in the test room.
At the discretion of the test laboratory, the mass or water
delivered may be measured on either the inlet or outlet of the water
heater.
For water heaters designed to be used with a mixing valve and
that do not have a self-contained mixing valve, a mixing valve shall
be installed according to the water heater and/or mixing valve
manufacturer's installation instructions. If permitted by the water
heater and mixing valve manufacturer's instructions, the mixing
valve and cold water junction may be installed where the elbows are
located in the outlet and inlet line, respectively. If there are no
installation instructions for the mixing valve in the water heater
or mixing valve manufacturer's instructions, then the mixing valve
shall be installed on the outlet line and the cold water shall be
supplied from the inlet line from a junction installed downstream
from the location where the inlet water temperature is measured. The
outlet water temperature, water flow rate, and/or mass measuring
instrumentation, if installed on the outlet side of the water
heater, shall be installed downstream from the mixing valve.
4.4 Fuel and/or Electrical Power and Energy Consumption. Install
one or more instruments that measure, as appropriate, the quantity
and rate of electrical energy and/or fossil fuel consumption in
accordance with section 3 of this appendix.
4.5 Internal Storage Tank Temperature Measurements. For water
heaters with rated storage volumes greater than or equal to 20
gallons, install six temperature measurement sensors inside the
water heater tank with a vertical distance of at least 4 inches (100
mm) between successive sensors. For water heaters with rated storage
volumes between 2 and 20 gallons, install three temperature
measurement sensors inside the water heater tank. Position a
temperature sensor at the vertical midpoint of each of the six equal
volume nodes within a tank larger than 20 gallons or the three equal
volume nodes within a tank between 2 and 20 gallons. Nodes designate
the equal volumes used to evenly partition the total volume of the
tank. As much as is possible, the temperature sensor should be
positioned away from any heating elements, anodic protective
devices, tank walls, and flue pipe walls. If the tank cannot
accommodate six temperature sensors and meet the installation
requirements specified in this section, install the maximum number
of sensors that comply with the installation requirements. Install
the temperature sensors through:
(a) The anodic device opening;
(b) The relief valve opening; or
(c) The hot water outlet.
If installed through the relief valve opening or the hot water
outlet, a tee fitting or outlet piping, as applicable, must be
installed as close as possible to its original location. If the
relief valve temperature sensor is relocated, and it no longer
extends into the top of the tank, install a substitute relief valve
that has a sensing element that can reach into the tank. If the hot
water outlet includes a heat trap, install the heat trap on top of
the tee fitting. Cover any added fittings with thermal insulation
having an R value between 4 and 8 h[middot]ft\2\[middot] [deg]F/Btu
(0.7 and 1.4 m\2\[middot] [deg]C/W). If temperature measurement
sensors cannot be installed within the water heater, follow the
alternate procedures in section 5.4.2.2 of this appendix.
4.6 Ambient Air Temperature Measurement. Install an ambient air
temperature sensor at the vertical midpoint of the water heater and
approximately 2 feet (610 mm) from the surface of the water heater.
Shield the sensor against radiation.
4.7 Inlet and Outlet Water Temperature Measurements. Install
temperature sensors in the cold-water inlet pipe and hot-water
outlet pipe as shown in Figures 1, 2, 3, 4, 5, 6, 7a, and 7b of
section 7 of this appendix, as applicable.
4.8 Flow Control. Install a valve or valves to provide flow as
specified in sections 5.3 and 5.4 of this appendix.
4.9 Flue Requirements.
4.9.1 Gas-Fired Water Heaters. Establish a natural draft in the
following manner. For gas-fired water heaters with a vertically
discharging draft hood outlet, connect to the draft hood outlet a 5-
foot (1.5-meter) vertical vent pipe extension with a diameter equal
to the largest flue collar size of the draft hood. For gas-fired
water heaters with a horizontally discharging draft hood outlet,
connect to the draft hood outlet a 90-degree elbow with a diameter
equal to the largest flue collar size of the draft hood, connect a
5-foot (1.5-meter) length of vent pipe to that elbow, and orient the
vent pipe to discharge vertically upward. Install direct-vent gas-
fired water heaters with venting equipment specified by the
manufacturer in the I&O manual using the minimum vertical and
horizontal lengths of vent pipe recommended by the manufacturer.
4.9.2 Oil-Fired Water Heaters. Establish a draft at the flue
collar at the value specified by the manufacturer in the I&O manual.
Establish the draft by using a sufficient length of vent pipe
connected to the water heater flue outlet, and directed vertically
upward. For an oil-fired water heater with a horizontally
discharging draft hood outlet, connect to the draft hood outlet a
90-degree elbow with a diameter equal to the largest flue collar
size of the draft hood, connect to the elbow fitting a length of
vent pipe sufficient to establish the draft, and orient the vent
pipe to discharge vertically upward. Direct-vent oil-fired water
heaters should be installed with venting equipment as specified by
the manufacturer in the I&O manual, using the minimum vertical and
horizontal
[[Page 40478]]
lengths of vent pipe recommended by the manufacturer.
4.10 Storage Tank Requirement for Circulating Water Heaters. On
or after the compliance date of a final rule reviewing potential
amended energy conservation standards for these products published
after June 21, 2023,when testing a gas-fired, oil-fired, or electric
resistance circulating water heater (i.e., any circulating water
heater that does not use a heat pump), the tank to be used for
testing shall be an unfired hot water storage tank having volume
between 80 and 120 gallons (364-546 liters) determined using the
method specified in section 5.2.1 that meets but does not exceed the
minimum energy conservation standards required according to 10 CFR
431.110. When testing a heat pump circulating water heater, the tank
to be used for testing shall be an electric storage water heater
that has a measured volume of 40 gallons (5 gallons),
has a First-Hour Rating greater than or equal to 51 gallons and less
than 75 gallons resulting in classification under the medium draw
pattern, and has a rated UEF equal to the minimum UEF standard
specified at Sec. 430.32(d), rounded to the nearest 0.01. The
operational mode of the heat pump circulating water heater and
storage water heater paired system shall be set in accordance with
section 5.1.1 of this appendix. If the circulating water heater is
supplied with a separate non-integrated circulating pump, install
this pump as per the manufacturer's installation instructions and
include its power consumption in energy use measurements.
4.11 External Communication. If the water heater can connect to
an external network or controller, any external communication or
connection shall be disabled for the duration of testing; however,
the communication module shall remain in an ``on'' state.
5. Test Procedures.
5.1 Operational Mode Selection. For water heaters that allow for
multiple user-selected operational modes, all procedures specified
in this appendix shall be carried out with the water heater in the
same operational mode (i.e., only one mode).
5.1.1 Testing at Normal Setpoint. The operational mode shall be
the default mode (or similarly named, suggested mode for normal
operation) as defined by the manufacturer in the I&O manual for
giving selection guidance to the consumer. For heat pump water
heaters, if a default mode is not defined in the product literature,
each test shall be conducted under an operational mode in which both
the heat pump and any electric resistance back-up heating element(s)
are activated by the unit's control scheme, and which can achieve
the internal storage tank temperature specified in this test
procedure; if multiple operational modes meet these criteria, the
water heater shall be tested under the most energy-intensive mode.
If no default mode is specified and the unit does not offer an
operational mode that utilizes both the heat pump and the electric
resistance back-up heating element(s), the first-hour rating test
and the 24-hour simulated-use test shall be tested in heat-pump-only
mode. For other types of water heaters where a default mode is not
specified, test the unit in all modes and rate the unit using the
results of the most energy-intensive mode.
5.1.2 High Temperature Testing. This paragraph applies to
electric storage water heaters that are capable of heating their
stored water above the target delivery temperature without
initiation from a utility or third-party demand-response program,
except for those that meet the definition of ``heat pump-type''
water heater at 10 CFR 430.2.
For those equipped with factory-installed or built-in mixing
valves, set the unit to maintain the highest mean tank temperature
possible while delivering water at 125 [deg]F 5 [deg]F.
For those not so equipped, install an ASSE 1017-certified mixing
valve in accordance with the provisions in section 4.3 and adjust
the valve to deliver water at 125 [deg]F 5 [deg]F when
the water heater is operating at its highest storage tank
temperature setpoint. Maintain this setting throughout the entirety
of the test.
5.2 Water Heater Preparation.
5.2.1 Determination of Storage Tank Volume. For water heaters
with a rated storage volume greater than or equal to 2 gallons and
for separate storage tanks used for testing circulating water
heaters, determine the storage capacity, Vst, of the
water heater or separate storage tank under test, in gallons
(liters), by subtracting the tare weight, Wt, (measured
while the tank is empty) from the gross weight of the storage tank
when completely filled with water at the supply water temperature
specified in section 2.3 of this appendix, Wf, (with all
air eliminated and line pressure applied as described in section 2.6
of this appendix) and dividing the resulting net weight by the
density of water at the measured temperature.
5.2.2 Setting the Outlet Discharge Temperature.
5.2.2.1 Flow-Activated Water Heaters, including certain
instantaneous water heaters and certain storage-type water heaters.
Initiate normal operation of the water heater at the design power
rating. Monitor the discharge water temperature and set to the value
specified in section 2.5 of this appendix in accordance with the
manufacturer's I&O manual. If the water heater is not capable of
providing this discharge temperature when the flow rate is 1.7
gallons 0.25 gallons per minute (6.4 liters 0.95 liters per minute), then adjust the flow rate as
necessary to achieve the specified discharge water temperature. Once
the proper temperature control setting is achieved, the setting must
remain fixed for the duration of the maximum GPM test and the 24-
hour simulated-use test.
5.2.2.2 All Other Water Heaters.
5.2.2.2.1 Water Heaters with a Single Temperature Controller.
5.2.2.2.1.1 Water Heaters with Rated Volumes Less than 20
Gallons. Starting with a tank at the supply water temperature as
specified in section 2.3 of this appendix, initiate normal operation
of the water heater. After cut-out, initiate a draw from the water
heater at a flow rate of 1.0 gallon 0.25 gallons per
minute (3.8 liters 0.95 liters per minute) for 2
minutes. Starting 15 seconds after commencement of the draw, record
the outlet temperature at 15-second intervals until the end of the
2-minute period. Determine whether the maximum outlet temperature is
within the range specified in section 2.4 of this appendix. If not,
turn off the water heater, adjust the temperature controller, and
then drain and refill the tank with supply water at the temperature
specified in section 2.3 of this appendix. Then, once again,
initiate normal operation of the water heater, and repeat the 2-
minute outlet temperature test following cut-out. Repeat this
sequence until the maximum outlet temperature during the 2-minute
test is within the range specified in section 2.4 of this appendix.
Once the proper temperature control setting is achieved, the setting
must remain fixed for the duration of the first-hour rating test and
the 24-hour simulated-use test.
5.2.2.2.1.2 Water Heaters with Rated Volumes Greater than or
Equal to 20 Gallons. Starting with a tank at the supply water
temperature specified in section 2.3 of this appendix, initiate
normal operation of the water heater. After cut-out, initiate a draw
from the water heater at a flow rate of 1.7 gallons
0.25 gallons per minute (6.4 liters 0.95 liters per
minute) for 5 minutes. Starting 15 seconds after commencement of the
draw, record the outlet temperature at 15-second intervals until the
end of the 5-minute period. Determine whether the maximum outlet
temperature is within the range specified in section 2.4 of this
appendix. If not, turn off the water heater, adjust the temperature
controller, and then drain and refill the tank with supply water at
the temperature specified in section 2.3 of this appendix. Then,
once again, initiate normal operation of the water heater, and
repeat the 5-minute outlet temperature test following cut-out.
Repeat this sequence until the maximum outlet temperature during the
5-minute test is within the range specified in section 2.4 of this
appendix. Once the proper temperature control setting is achieved,
the setting must remain fixed for the duration of the first-hour
rating test and the 24-hour simulated-use test.
5.2.2.2.2 Water Heaters with Two or More Temperature
Controllers. Verify the temperature controller set-point while
removing water in accordance with the procedure set forth for the
first-hour rating test in section 5.3.3 of this appendix. The
following criteria must be met to ensure that all temperature
controllers are set to deliver water in the range specified in
section 2.4 of this appendix:
(a) At least 50 percent of the water drawn during the first draw
of the first-hour rating test procedure shall be delivered at a
temperature within the range specified in section 2.4 of this
appendix.
(b) No water is delivered above the range specified in section
2.4 of this appendix during first-hour rating test.
(c) The delivery temperature measured 15 seconds after
commencement of each draw begun prior to an elapsed time of 60
minutes from the start of the test shall be within the range
specified in section 2.4 of this appendix.
[[Page 40479]]
If these conditions are not met, turn off the water heater,
adjust the temperature controllers, and then drain and refill the
tank with supply water at the temperature specified in section 2.3
of this appendix. Repeat the procedure described at the start of
section 5.2.2.2.2 of this appendix until the criteria for setting
the temperature controllers is met.
If the conditions stated above are met, the data obtained during
the process of verifying the temperature control set-points may be
used in determining the first-hour rating provided that all other
conditions and methods required in sections 2 and 5.2.4 of this
appendix in preparing the water heater were followed.
5.2.3 Power Input Determination. For all water heaters except
electric types, initiate normal operation (as described in section
5.1 of this appendix) and determine the power input, P, to the main
burners (including pilot light power, if any) after 15 minutes of
operation. Adjust all burners to achieve an hourly Btu (kJ) rating
that is within 2% of the maximum input rate value
specified by the manufacturer. For an oil-fired water heater, adjust
the burner to give a CO2 reading recommended by the
manufacturer and an hourly Btu (kJ) rating that is within 2% of the maximum input rate specified by the manufacturer.
Smoke in the flue may not exceed No. 1 smoke as measured by the
procedure in ASTM D2156 (R2018), including the conditions as
specified in ASTM E97-1987 as referenced in ASTM D2156 (R2018). If
the input rating is not within 2%, first increase or
decrease the fuel pressure within the tolerances specified in
section 2.7.2, 2.7.3 or 2.7.4 (as applicable) of this appendix until
it is 2% of the maximum input rate value specified by
the manufacturer. If, after adjusting the fuel pressure, the fuel
input rate cannot be achieved within 2 percent of the
maximum input rate value specified by the manufacturer, for gas-
fired models increase or decrease the gas supply pressure within the
range specified by the manufacturer. Finally, if the measured fuel
input rate is still not within 2 percent of the maximum
input rate value specified by the manufacturer, modify the gas inlet
orifice, if so equipped, as necessary to achieve a fuel input rate
that is within 2 percent of the maximum input rate value
specified by the manufacturer.
5.2.4 Soak-In Period for Water Heaters with Rated Storage
Volumes Greater than or Equal to 2 Gallons. For water heaters with a
rated storage volume greater than or equal to 2 gallons (7.6
liters), the water heater must sit filled with water, connected to a
power source, and without any draws taking place for at least 12
hours after initially being energized so as to achieve the nominal
temperature set-point within the tank and with the unit connected to
a power source.
5.3 Delivery Capacity Tests.
5.3.1 General. For flow-activated water heaters, conduct the
maximum GPM test, as described in section 5.3.2, Maximum GPM Rating
Test for Flow-Activated Water Heaters, of this appendix. For all
other water heaters, conduct the first-hour rating test as described
in section 5.3.3 of this appendix.
5.3.2 Maximum GPM Rating Test for Flow-Activated Water Heaters.
Establish normal water heater operation at the design power rating
with the discharge water temperature set in accordance with section
5.2.2.1 of this appendix.
For this 10-minute test, either collect the withdrawn water for
later measurement of the total mass removed or use a water meter to
directly measure the water mass of volume removed. Initiate water
flow through the water heater and record the inlet and outlet water
temperatures beginning 15 seconds after the start of the test and at
subsequent 5-second intervals throughout the duration of the test.
At the end of 10 minutes, turn off the water. Determine and record
the mass of water collected, M10m, in pounds (kilograms),
or the volume of water, V10m, in gallons (liters).
5.3.3 First-Hour Rating Test.
5.3.3.1 General. During hot water draws for water heaters with
rated storage volumes greater than or equal to 20 gallons, remove
water at a rate of 3.0 0.25 gallons per minute (11.4
0.95 liters per minute). During hot water draws for
water heaters with rated storage volumes below 20 gallons, remove
water at a rate of 1.5 0.25 gallon per minute (5.7
0.95 liters per minute). Collect the water in a
container that is large enough to hold the volume removed during an
individual draw and is suitable for weighing at the termination of
each draw to determine the total volume of water withdrawn. As an
alternative to collecting the water, a water meter may be used to
directly measure the water mass or volume withdrawn during each
draw.
5.3.3.2 Draw Initiation Criteria. Begin the first-hour rating
test by starting a draw on the water heater. After completion of
this first draw, initiate successive draws based on the following
criteria. For gas-fired and oil-fired water heaters, initiate
successive draws when the temperature controller acts to reduce the
supply of fuel to the main burner. For electric water heaters having
a single element or multiple elements that all operate
simultaneously, initiate successive draws when the temperature
controller acts to reduce the electrical input supplied to the
element(s). For electric water heaters having two or more elements
that do not operate simultaneously, initiate successive draws when
the applicable temperature controller acts to reduce the electrical
input to the energized element located vertically highest in the
storage tank. For heat pump water heaters that do not use
supplemental, resistive heating, initiate successive draws
immediately after the electrical input to the compressor is reduced
by the action of the water heater's temperature controller. For heat
pump water heaters that use supplemental resistive heating, initiate
successive draws immediately after the electrical input to the first
of either the compressor or the vertically highest resistive element
is reduced by the action of the applicable water heater temperature
controller. This draw initiation criterion for heat pump water
heaters that use supplemental resistive heating, however, shall only
apply when the water located above the thermostat at cut-out is
heated to within the range specified in section 2.4 of this
appendix. If this criterion is not met, then the next draw should be
initiated once the heat pump compressor cuts out.
5.3.3.3 Test Sequence. Establish normal water heater operation.
If the water heater is not presently operating, initiate a draw. The
draw may be terminated any time after cut-in occurs. After cut-out
occurs (i.e., all temperature controllers are satisfied), if the
water heater can have its internal tank temperatures measured,
record the internal storage tank temperature at each sensor
described in section 4.5 of this appendix every one minute, and
determine the mean tank temperature by averaging the values from
these sensors.
Initiate a draw after a maximum mean tank temperature (the
maximum of the mean temperatures of the individual sensors) has been
observed following a cut-out. If the water heater cannot have its
internal tank temperatures measured, wait 5 minutes after cut-out.
Record the time when the draw is initiated and designate it as an
elapsed time of zero ([tau]* = 0). (The superscript * is used to
denote variables pertaining to the first-hour rating test). Record
the outlet water temperature beginning 15 seconds after the draw is
initiated and at 5-second intervals thereafter until the draw is
terminated. Determine the maximum outlet temperature that occurs
during this first draw and record it as T*max,1. For the
duration of this first draw and all successive draws, in addition,
monitor the inlet temperature to the water heater to ensure that the
required supply water temperature test condition specified in
section 2.3 of this appendix is met. Terminate the hot water draw
when the outlet temperature decreases to T*max,1-15
[deg]F (T*max,1-8.3 [deg]C). (Note, if the outlet
temperature does not decrease to T*max,1-15 [deg]F
(T*max,1-8.3 [deg]C) during the draw, then hot water
would be drawn continuously for the duration of the test. In this
instance, the test would end when the temperature decreases to
T*max,1-15 [deg]F (T*max,1-8.3 [deg]C) after
the electrical power and/or fuel supplied to the water heater is
shut off, as described in the following paragraphs.) Record this
temperature as T*min,1. Following draw termination,
determine the average outlet water temperature and the mass or
volume removed during this first draw and record them as
T*del,i and M*1 or V*1,
respectively.
Initiate a second and, if applicable, successive draw(s) each
time the applicable draw initiation criteria described in section
5.3.3.2 of this appendix are satisfied. As required for the first
draw, record the outlet water temperature 15 seconds after
initiating each draw and at 5-second intervals thereafter until the
draw is terminated. Determine the maximum outlet temperature that
occurs during each draw and record it as T*max,i, where
the subscript i refers to the draw number. Terminate each hot water
draw when the outlet temperature decreases to T*max,i-15
[deg]F (T*max,i-8.3 [deg]C). Record this temperature as
T*min,i. Calculate and record the average outlet
temperature and the mass or volume removed during each draw
(T*del,i and M*i or V*i,
respectively). Continue this sequence of draw and recovery until one
hour after the start of the test, then shut off the electrical power
and/or fuel supplied to the water heater.
[[Page 40480]]
If a draw is occurring at one hour from the start of the test,
continue this draw until the outlet temperature decreases to
T*max,n-15 [deg]F (T*max,n-8.3 [deg]C), at
which time the draw shall be immediately terminated. (The subscript
n shall be used to denote measurements associated with the final
draw.) If a draw is not occurring one hour after the start of the
test, initiate a final draw at one hour, regardless of whether the
criteria described in section 5.3.3.2 of this appendix are
satisfied. This draw shall proceed for a minimum of 30 seconds and
shall terminate when the outlet temperature first indicates a value
less than or equal to the cut-off temperature used for the previous
draw (T*min,n-1). If an outlet temperature greater than
T*min,n-1 is not measured within 30 seconds of initiation
of the draw, zero additional credit shall be given towards first-
hour rating (i.e., M*n = 0 or V*n = 0) based
on the final draw. After the final draw is terminated, calculate and
record the average outlet temperature and the mass or volume removed
during the final draw (T*del,n and M*n or
V*n, respectively).
5.4 24-Hour Simulated-Use Test.
5.4.1 Selection of Draw Pattern. The water heater will be tested
under a draw profile that depends upon the first-hour rating
obtained following the test prescribed in section 5.3.3 of this
appendix, or the maximum GPM rating obtained following the test
prescribed in section 5.3.2 of this appendix, whichever is
applicable. For water heaters that have been tested according to the
first-hour rating procedure, one of four different patterns shall be
applied based on the measured first-hour rating, as shown in Table I
of this section. For water heater that have been tested according to
the maximum GPM rating procedure, one of four different patterns
shall be applied based on the maximum GPM, as shown in Table II of
this section.
Table I--Draw Pattern To Be Used Based on First-Hour Rating
------------------------------------------------------------------------
Draw pattern to be
First-hour rating greater than . . . and first- used in the 24-
or equal to: hour rating less hour simulated-use
than: test
------------------------------------------------------------------------
0 gallons....................... 18 gallons........ Very-Small-Usage
(Table III.1).
18 gallons...................... 51 gallons........ Low-Usage (Table
III.2).
51 gallons...................... 75 gallons........ Medium-Usage
(Table III.3).
75 gallons...................... No upper limit.... High-Usage (Table
III.4).
------------------------------------------------------------------------
Table II--Draw Pattern To Be Used Based on Maximum GPM Rating
------------------------------------------------------------------------
Draw pattern to be
Maximum GPM rating greater than and maximum GPM used in the 24-
or equal to: rating less than: hour simulated-use
test
------------------------------------------------------------------------
0 gallons/minute................ 1.7 gallons/minute Very-Small-Usage
(Table III.1).
1.7 gallons/minute.............. 2.8 gallons/minute Low-Usage (Table
III.2).
2.8 gallons/minute.............. 4 gallons/minute.. Medium-Usage
(Table III.3).
4 gallons/minute................ No upper limit.... High-Usage (Table
III.4).
------------------------------------------------------------------------
The draw patterns are provided in Tables III.1 through III.4 in
section 5.5 of this appendix. Use the appropriate draw pattern when
conducting the test sequence provided in section 5.4.2 of this
appendix for water heaters with rated storage volumes greater than
or equal to 2 gallons or section 5.4.3 of this appendix for water
heaters with rated storage volumes less than 2 gallons.
5.4.2 Test Sequence for Water Heater With Rated Storage Volume
Greater Than or Equal to 2 Gallons.
If the water heater is turned off, fill the water heater with
supply water at the temperature specified in section 2.3 of this
appendix and maintain supply water pressure as described in section
2.6 of this appendix. Turn on the water heater and associated heat
pump unit, if present. If turned on in this fashion, the soak-in
period described in section 5.2.4 of this appendix shall be
implemented. If the water heater has undergone a first-hour rating
test prior to conduct of the 24-hour simulated-use test, allow the
water heater to fully recover after completion of that test such
that the main burner, heating elements, or heat pump compressor of
the water heater are no longer raising the temperature of the stored
water. In all cases, the water heater shall sit idle for 1 hour
prior to the start of the 24-hour test; during which time no water
is drawn from the unit, and there is no energy input to the main
heating elements, heat pump compressor, and/or burners.
For water heaters that can have their internal storage tank
temperature measured directly, perform testing in accordance with
the instructions in section 5.4.2.1 of this appendix. For water
heaters that cannot have their internal tank temperatures measured,
perform testing in accordance with the instructions in section
5.4.2.2. of this appendix.
5.4.2.1 Water Heaters Which Can Have Internal Storage Tank
Temperature Measured Directly.
After the 1-hour period specified in section 5.4.2 of this
appendix, the 24-hour simulated-use test will begin. One minute
prior to the start of the 24-hour simulated-use test, record the
mean tank temperature (T0).
At the start of the 24-hour simulated-use test, record the
electrical and/or fuel measurement readings, as appropriate. Begin
the 24-hour simulated-use test by withdrawing the volume specified
in the appropriate table in section 5.5 of this appendix (i.e.,
Table III.1, Table III.2, Table III.3, or Table III.4, depending on
the first-hour rating or maximum GPM rating) for the first draw at
the flow rate specified in the applicable table. Record the time
when this first draw is initiated and assign it as the test elapsed
time ([tau]) of zero (0). Record the average storage tank and
ambient temperature every minute throughout the 24-hour simulated-
use test. At the elapsed times specified in the applicable draw
pattern table in section 5.5 of this appendix for a particular draw
pattern, initiate additional draws pursuant to the draw pattern,
removing the volume of hot water at the prescribed flow rate
specified by the table. The maximum allowable deviation from the
specified volume of water removed for any single draw taken at a
nominal flow rate of 1.0 GPM or 1.7 GPM is 0.1 gallons
(0.4 liters). The maximum allowable deviation from the
specified volume of water removed for any single draw taken at a
nominal flow rate of 3.0 GPM is 0.25 gallons (0.9
liters). The quantity of water withdrawn during the last draw shall
be increased or decreased as necessary such that the total volume of
water withdrawn equals the prescribed daily amount for that draw
pattern 1.0 gallon (3.8 liters). If this
adjustment to the volume drawn during the last draw results in no
draw taking place, the test is considered invalid.
All draws during the 24-hour simulated-use test shall be made at
the flow rates specified in the applicable draw pattern table in
section 5.5 of this appendix, within a tolerance of 0.25
gallons per minute (0.9 liters per minute). Measurements
of the inlet and outlet temperatures shall be made 15 seconds after
the draw is initiated and at every subsequent 3-second interval
throughout the duration of each draw. Calculate and record the mean
of the hot water discharge temperature and the cold water inlet
temperature for each draw Tdel,i and Tin,i).
Determine and record the net mass or volume removed (Mi
or Vi), as appropriate, after each draw.
The first recovery period is the time from the start of the 24-
hour simulated-use test and continues during the temperature rise of
the stored water until the first cut-out; if the cut-out occurs
during a subsequent draw, the first recovery period includes the
time until the draw of water from the tank stops. If, after the
first cut-out occurs but during a subsequent draw, a subsequent cut-
in occurs prior to the draw completion, the first
[[Page 40481]]
recovery period includes the time until the subsequent cut-out
occurs, prior to another draw. The first recovery period may
continue until a cut-out occurs when water is not being removed from
the water heater or a cut-out occurs during a draw and the water
heater does not cut-in prior to the end of the draw.
At the end of the first recovery period, record the maximum mean
tank temperature observed after cut-out (Tmax,1). At the
end of the first recovery period, record the total energy consumed
by the water heater from the beginning of the test (Qr),
including all fossil fuel and/or electrical energy use, from the
main heat source and auxiliary equipment including, but not limited
to, burner(s), resistive elements(s), compressor, fan, controls,
pump, etc., as applicable.
The start of the portion of the test during which the standby
loss coefficient is determined depends upon whether the unit has
fully recovered from the first draw cluster. If a recovery is
occurring at or within five minutes after the end of the final draw
in the first draw cluster, as identified in the applicable draw
pattern table in section 5.5 of this appendix, then the standby
period starts when a maximum mean tank temperature is observed
starting five minutes after the end of the recovery period that
follows that draw. If a recovery does not occur at or within five
minutes after the end of the final draw in the first draw cluster,
as identified in the applicable draw pattern table in section 5.5 of
this appendix, then the standby period starts five minutes after the
end of that draw. Determine and record the total electrical energy
and/or fossil fuel consumed from the beginning of the test to the
start of the standby period (Qsu,0).
In preparation for determining the energy consumed during
standby, record the reading given on the electrical energy (watt-
hour) meter, the gas meter, and/or the scale used to determine oil
consumption, as appropriate. Record the mean tank temperature at the
start of the standby period (Tsu,0). At 1-minute
intervals, record ambient temperature, the electric and/or fuel
instrument readings, and the mean tank temperature until the next
draw is initiated. The end of the standby period is when the final
mean tank temperature is recorded, as described. Just prior to
initiation of the next draw, record the mean tank temperature
(Tsu,f). If the water heater is undergoing recovery when
the next draw is initiated, record the mean tank temperature
(Tsu,f) at the minute prior to the start of the recovery.
Determine the total electrical energy and/or fossil fuel energy
consumption from the beginning of the test to the end of the standby
period (Qsu,f). Record the time interval between the
start of the standby period and the end of the standby period
([tau]stby,1).
Following the final draw of the prescribed draw pattern and
subsequent recovery, allow the water heater to remain in the standby
mode until exactly 24 hours have elapsed since the start of the 24-
hour simulated-use test (i.e., since [tau] = 0). During the last
hour of the 24-hour simulated-use test (i.e., hour 23 of the 24-hour
simulated-use test), power to the main burner, heating element, or
compressor shall be disabled. At 24 hours, record the reading given
by the gas meter, oil meter, and/or the electrical energy meter as
appropriate. Determine the fossil fuel and/or electrical energy
consumed during the entire 24-hour simulated-use test and designate
the quantity as Q.
In the event that the recovery period continues from the end of
the last draw of the first draw cluster until the subsequent draw,
the standby period will start after the end of the first recovery
period after the last draw of the 24-hour simulated-use test, when
the temperature reaches the maximum mean tank temperature, though no
sooner than five minutes after the end of this recovery period. The
standby period shall last eight hours, so testing may extend beyond
the 24-hour duration of the 24-hour simulated-use test. Determine
and record the total electrical energy and/or fossil fuel consumed
from the beginning of the 24-hour simulated-use test to the start of
the 8-hour standby period (Qsu,0). In preparation for
determining the energy consumed during standby, record the
reading(s) given on the electrical energy (watt-hour) meter, the gas
meter, and/or the scale used to determine oil consumption, as
appropriate. Record the mean tank temperature at the start of the
standby period (Tsu,0). Record the mean tank temperature,
the ambient temperature, and the electric and/or fuel instrument
readings at 1-minute intervals until the end of the 8-hour period.
Record the mean tank temperature at the end of the 8-hour standby
period (Tsu,f). If the water heater is undergoing
recovery at the end of the standby period, record the mean tank
temperature (Tsu,f) at the minute prior to the start of
the recovery, which will mark the end of the standby period.
Determine the total electrical energy and/or fossil fuel energy
consumption from the beginning of the test to the end of the standby
period (Qsu,f). Record the time interval between the
start of the standby period and the end of the standby period as
[tau]stby,1. Record the average ambient temperature from
the start of the standby period to the end of the standby period
(Ta,stby,1). Record the average mean tank temperature
from the start of the standby period to the end of the standby
period (Tt,stby,1).
If the standby period occurred at the end of the first recovery
period after the last draw of the 24-hour simulated-use test, allow
the water heater to remain in the standby mode until exactly 24
hours have elapsed since the start of the 24-hour simulated-use test
(i.e., since [tau] = 0) or the end of the standby period, whichever
is longer. At 24 hours, record the mean tank temperature
(T24) and the reading given by the gas meter, oil meter,
and/or the electrical energy meter as appropriate. If the water
heater is undergoing a recovery at 24 hours, record the reading
given by the gas meter, oil meter, and/or electrical energy meter,
as appropriate, and the mean tank temperature (T24) at
the minute prior to the start of the recovery. Determine the fossil
fuel and/or electrical energy consumed during the 24 hours and
designate the quantity as Q.
Record the time during which water is not being withdrawn from
the water heater during the entire 24-hour period
([tau]stby,2). When the standby period occurs after the
last draw of the 24-hour simulated-use test, the test may extend
past hour 24. When this occurs, the measurements taken after hour 24
apply only to the calculations of the standby loss coefficient. All
other measurements during the time between hour 23 and hour 24
remain the same.
5.4.2.2 Water Heaters Which Cannot Have Internal Storage Tank
Temperature Measured Directly.
After the water heater has undergone a 1-hour idle period (as
described in section 5.4.2 of this appendix), deactivate the burner,
compressor, or heating element(s).
Remove water from the storage tank by performing a continuous
draw at the flow rate specified for the first draw of applicable
draw pattern for the 24-hour simulated use test in section 5.5 of
this appendix within a tolerance of 0.25 gallons per
minute (0.9 liters per minute). While removing the hot
water, measure the inlet and outlet temperature after initiating the
draw at 3-second intervals. Remove water until the outlet water
temperature is within 2 [deg]F (1.1 [deg]C)
of the inlet water temperature for 15 consecutive seconds. Determine
the mean tank temperature using section 6.3.77 of this appendix and
assign this value of Tst for T0,
Tmax,1, and Tsu,0.
After completing the draw, reactivate the burner, compressor, or
heating elements(s) and allow the unit to fully recover such that
the main burner, heating elements, or heat pump compressor is no
longer raising the temperature of the stored water. Let the water
heater sit idle again for 1 hour prior to beginning the 24-hour
test, during which time no water shall be drawn from the unit, and
there shall be no energy input to the main heating elements. After
the 1-hour period, the 24-hour simulated-use test will begin.
At the start of the 24-hour simulated-use test, record the
electrical and/or fuel measurement readings, as appropriate. Begin
the 24-hour simulated-use test by withdrawing the volume specified
in the appropriate table in section 5.5 of this appendix (i.e.,
Table III.1, Table III.2, Table III.3, or Table III.4, depending on
the first-hour rating or maximum GPM rating) for the first draw at
the flow rate specified in the applicable table. Record the time
when this first draw is initiated and assign it as the test elapsed
time ([tau]) of zero (0). Record the average ambient temperature
every minute throughout the 24-hour simulated-use test. At the
elapsed times specified in the applicable draw pattern table in
section 5.5 of this appendix for a particular draw pattern, initiate
additional draws pursuant to the draw pattern, removing the volume
of hot water at the prescribed flow rate specified by the table. The
maximum allowable deviation from the specified volume of water
removed for any single draw taken at a nominal flow rate of 1.0 GPM
or 1.7 GPM is 0.1 gallons ( 0.4 liters).
The maximum allowable deviation from the specified volume of water
removed for any single draw taken at a nominal flow rate of 3.0 GPM
is 0.25 gallons (0.9 liters). The quantity of water
withdrawn during the last draw shall be increased or decreased as
necessary such that the total volume of water withdrawn equals the
prescribed daily amount for that draw
[[Page 40482]]
pattern 1.0 gallon ( 3.8 liters). If this
adjustment to the volume drawn during the last draw results in no
draw taking place, the test is considered invalid.
All draws during the 24-hour simulated-use test shall be made at
the flow rates specified in the applicable draw pattern table in
section 5.5 of this appendix, within a tolerance of 0.25
gallons per minute (0.9 liters per minute). Measurements
of the inlet and outlet temperatures shall be made 15 seconds after
the draw is initiated and at every subsequent 3-second interval
throughout the duration of each draw. Calculate and record the mean
of the hot water discharge temperature and the cold water inlet
temperature for each draw Tdel,i and Tin,i).
Determine and record the net mass or volume removed (Mi
or Vi), as appropriate, after each draw.
The first recovery period is the time from the start of the 24-
hour simulated-use test and continues until the first cut-out; if
the cut-out occurs during a subsequent draw, the first recovery
period includes the time until the draw of water from the tank
stops. If, after the first cut-out occurs but during a subsequent
draw, a subsequent cut-in occurs prior to the draw completion, the
first recovery period includes the time until the subsequent cut-out
occurs, prior to another draw. The first recovery period may
continue until a cut-out occurs when water is not being removed from
the water heater or a cut-out occurs during a draw and the water
heater does not cut-in prior to the end of the draw.
At the end of the first recovery period, record the total energy
consumed by the water heater from the beginning of the test
(Qr), including all fossil fuel and/or electrical energy
use, from the main heat source and auxiliary equipment including,
but not limited to, burner(s), resistive elements(s), compressor,
fan, controls, pump, etc., as applicable.
The standby period begins at five minutes after the first time a
recovery ends following last draw of the simulated-use test and
shall continue for 8 hours. At the end of the 8-hour standby period,
record the total amount of time elapsed since the start of the 24-
hour simulated-use test (i.e., since [tau] = 0).
Determine and record the total electrical energy and/or fossil
fuel consumed from the beginning of the 24-hour simulated-use test
to the start of the 8-hour standby period (Qsu,0). In
preparation for determining the energy consumed during standby,
record the reading(s) given on the electrical energy (watt-hour)
meter, the gas meter, and/or the scale used to determine oil
consumption, as appropriate. Record the ambient temperature and the
electric and/or fuel instrument readings at 1-minute intervals until
the end of the 8-hour period. At the 8-hour mark, deactivate the
water heater before drawing water from the tank. Remove water from
the storage tank by performing a continuous draw atthe flow rate
specified for the first draw of applicable draw pattern for the 24-
hour simulated use test in section 5.5 of this appendix within a
tolerance of 0.25 gallons per minute (0.9
liters per minute). While removing the hot water, measure the inlet
and outlet temperature after initiating the draw at 3-second
intervals. Remove water until the outlet water temperature is within
2 [deg]F (1.1 [deg]C) of the inlet water
temperature for 15 consecutive seconds. Determine the mean tank
temperature using section 6.3.77 of this appendix and assign this
value of Tst for Tsu,f and T24.
Determine the total electrical energy and/or fossil fuel energy
consumption from the beginning of the test to the end of the standby
period (Qsu,f). Record the time interval between the
start of the standby period and the end of the standby period as
[tau]stby,1. Record the average ambient temperature from
the start of the standby period to the end of the standby period
(Ta,stby,1). The average mean tank temperature from the
start of the standby period to the end of the standby period
(Tt,stby,1) shall be the average of Tsu,0 and
Tsu,f.
5.4.3 Test Sequence for Water Heaters With Rated Storage Volume
Less Than 2 Gallons.
Establish normal operation with the discharge water temperature
at 125 [deg]F 5 [deg]F (51.7 [deg]C 2.8
[deg]C) and set the flow rate as determined in section 5.2 of this
appendix. Prior to commencement of the 24-hour simulated-use test,
the unit shall remain in an idle state in which controls are active
but no water is drawn through the unit for a period of one hour.
With no draw occurring, record the reading given by the gas meter
and/or the electrical energy meter as appropriate. Begin the 24-hour
simulated-use test by withdrawing the volume specified in Tables
III.1 through III.4 of section 5.5 of this appendix for the first
draw at the flow rate specified. Record the time when this first
draw is initiated and designate it as an elapsed time, [tau], of 0.
At the elapsed times specified in Tables III.1 through III.4 for a
particular draw pattern, initiate additional draws, removing the
volume of hot water at the prescribed flow rate specified in Tables
III.1 through III.4. The maximum allowable deviation from the
specified volume of water removed for any single draw taken at a
nominal flow rate less than or equal to 1.7 GPM (6.4 L/min) is
