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Rule2023-11429

Energy Conservation Program: Test Procedure for Consumer Water Heaters and Residential-Duty Commercial Water Heaters

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Published

June 21, 2023

Effective

July 21, 2023

Issuing agencies

Energy Department

Abstract

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.

Full Text

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<title>Federal Register, Volume 88 Issue 118 (Wednesday, June 21, 2023)</title>
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[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 [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-11429]

[[Page 40405]]

Vol. 88

Wednesday,

No. 118

June 21, 2023

Part II

Department of Energy

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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]]

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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.

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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 <a href="http://www.regulations.gov">www.regulations.gov</a>.
All documents in the docket are listed in the <a href="http://www.regulations.gov">www.regulations.gov</a>
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: <a href="http://www.regulations.gov/docket/EERE-2019-BT-TP-0032">www.regulations.gov/docket/EERE-2019-BT-TP-0032</a>. 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: <a href="/cdn-cgi/l/email-protection#773607071b1e1619141224031619131605130426021204031e1819043712125913181259101801">[email&#160;protected]</a>.

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: <a href="/cdn-cgi/l/email-protection#327342425e5b535c51576146535c565340564163475741465b5d5c417257571c565d571c555d44">[email&#160;protected]</a>.
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: <a href="/cdn-cgi/l/email-protection#7e3b0c171d502d0a1f0d3e160f501a111b50191108">[email&#160;protected]</a>.

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: <a href="http://www.ashrae.org">www.ashrae.org</a>.
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: <a href="http://www.astm.org">www.astm.org</a>.
Copies of ASTM E97-1987 (W1991) are reasonably available from
standards resellers including GlobalSpec's Engineering 360 (<a href="https://standards.globalspec.com/std/3801495/astm-e97-82-1987">https://standards.globalspec.com/std/3801495/astm-e97-82-1987</a>) 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))
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\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.
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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))
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\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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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))
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\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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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))
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\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))
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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).
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\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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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) <plus-minus>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\
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\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).

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[[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\
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\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.
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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 <plus-minus>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 <plus-minus>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: <a href="http://www.energystar.gov/products/spec/residential_water_heaters_specification_version_5_0_pd">www.energystar.gov/products/spec/residential_water_heaters_specification_version_5_0_pd</a> (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
<a href="http://www.regulations.gov">www.regulations.gov</a> 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 <a href="http://www.regulations.gov">www.regulations.gov</a>). 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 <plus- rate during the industry TP
minus> 0.25 gpm (3.8 <plus- FHR test to be ASHRAE 118.2-
minus> 0.95 L/min) for water 1.5 <plus-minus> 2022.
heaters with a rated storage 0.25 gpm (5.7
volume less than 20 gallons. <plus-minus> 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 <plus- electric supply DOE to reduce
minus>1 percent of the rated voltage to be burden.
voltage for the entire test. within <plus-
minus>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 <plus-minus> 2.5 temperature for
[deg]F. non-heat pump
water heaters
within a range of
67.5 [deg]F <plus-
minus> 5 [deg]F,
and with an
average of 67.5
[deg]F <plus-
minus> 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 <plus-minus> 1 temperature for
[deg]F. heat pump water
heaters within a
range of 67.5
[deg]F <plus-
minus> 5 [deg]F,
and with an
average of 67.5
[deg]F <plus-
minus> 1 [deg]F
during recoveries
and an average of
67.5 [deg]F <plus-
minus> 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 <plus-minus>2 for heat pump
percent. water heaters
within a range of
50 percent <plus-
minus>5 percent,
and at an average
of 50 percent
<plus-minus>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 <plus- manifold pressure DOE to reduce
minus>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 <plus-
minus>10 percent
of the
manufacturer
recommended value
or <plus-
minus>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
<plus-minus>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 <plus-
minus>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 <plus-
minus> 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 <a href="http://www.ahrinet.org/search-standards/ahri-1430-demand-flexible-electric-storage-water-heaters">www.ahrinet.org/search-standards/ahri-1430-demand-flexible-electric-storage-water-heaters</a> (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:
<a href="http://www.energystar.gov/products/spec/residential_water_heaters_specification_version_5_0_pd">www.energystar.gov/products/spec/residential_water_heaters_specification_version_5_0_pd</a> (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 <plus-
minus> 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:
<a href="https://www.ahrinet.org/search-standards/ahri-1430-demand-flexible-electric-storage-water-heaters">https://www.ahrinet.org/search-standards/ahri-1430-demand-flexible-electric-storage-water-heaters</a>.) (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
<a href="http://www.regulations.doe.gov/certification-data/#q=Product_Group_s%3A*">www.regulations.doe.gov/certification-data/#q=Product_Group_s%3A*</a>.
---------------------------------------------------------------------------

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: <a href="http://neea.org/resources/advanced-water-heating-specification-v8.0">neea.org/resources/advanced-water-heating-specification-v8.0</a>) (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 <plus-minus>5 [deg]F (51.7 [deg]C <plus-
minus>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 <plus-minus>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: <a href="http://www.iccsafe.org/wp-content/uploads/is_stsc/Solar-UEF-Specification-for-Rating-Solar-Water-Heating-Systems-20201012.pdf">www.iccsafe.org/wp-content/uploads/is_stsc/Solar-UEF-Specification-for-Rating-Solar-Water-Heating-Systems-20201012.pdf</a> (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:
<bullet> ASHRAE 41.1-1986 (Reaffirmed 2006), Standard Method for
Temperature Measurement (ASHRAE 41.1-1986 (RA 2006)); and
<bullet> 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\
---------------------------------------------------------------------------

\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: <a href="http://www.astm.org">www.astm.org</a>. (Last
accessed on Sept. 20, 2022.)
---------------------------------------------------------------------------

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).
---------------------------------------------------------------------------

\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 <plus-
minus>2 [deg]F, and delivers water at a temperature of 125 [deg]F
<plus-minus>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.
---------------------------------------------------------------------------

\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 <plus-minus> 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.
---------------------------------------------------------------------------

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.
---------------------------------------------------------------------------

\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.
---------------------------------------------------------------------------

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
<plus-minus>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 <plus-minus> 0.25 gallons per minute (gpm)
(5.7 <plus-minus> 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 <plus-minus> 0.25 gpm (3.8 <plus-minus> 0.95 L/min). These flow
rates are lower than the 3.0 <plus-minus> 0.25 gpm (11.4 <plus-minus>
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 <plus-minus> 0.25 gpm (11.4 <plus-minus> 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 <plus-
minus> 0.25 gpm (5.7 <plus-minus> 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).
---------------------------------------------------------------------------

\42\ At 1.0 <plus-minus>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
<plus-minus> 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
<plus-minus> 0.25 gpm (5.7 <plus-minus> 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
<plus-minus> 0.25 gpm (3.8 <plus-minus> 0.95L/min) to 1.5 <plus-minus>
0.25 gpm (5.7 <plus-minus> 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 <plus-minus> 0.25 gpm (5.7 <plus-
minus> 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 <plus-minus> 0.25 gpm
(5.7 <plus-minus> 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.
---------------------------------------------------------------------------

\43\ Notice of Decision and Order in response to BWC petition
for waiver is available at: <a href="http://www.regulations.gov/document?D=EERE-2019-BT-WAV-0020-0008">www.regulations.gov/document?D=EERE-2019-BT-WAV-0020-0008</a>.
---------------------------------------------------------------------------

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

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