September 29, 2014

The Honorable Ernest Moniz 

Secretary of Energy 

U.S. Department of Energy 

Forrestal Building 

1000 Independence Avenue, S.W. 

Washington, D.C. 200585-1000 

Re: Petition for Repeal of Certain Provisions of DOE Rule on Test Procedures for 

Residential Water Heaters and Certain Commercial Water Heaters, Docket No. EERE2011-BT-TP-0042

Dear Secretary Moniz: 

The Air-Conditioning, Heating, and Refrigeration Institute (AHRI)1respectfully requests that the 

Department of Energy (DOE) repeal certain parts of the rule for efficiency test procedures for 

residential and commercial water heaters published in the Federal Register on July 11, 2014. 79 

Fed. Reg. 40542 (July 11, 2014). 

AHRI seeks repeal of the test procedure final rule2solely in regards to amendments made to

Sections 429.17 and 429.134 that address the rated volume of residential storage water heaters. 

The amendment to 429.17 (a)(ii)(C) requires that the rated volume value must be the mean of the 

storage volumes measured on the units that were tested to establish the model’s ratings. The 

amendment to 429.134 (d)(2) makes the rated volume subject to DOE’s enforcement provisions. 

These amendments in effect increase the stringency of the applicable minimum efficiency 

standards for residential gas, electric, and oil storage water heaters in violation of 42 U.S.C. § 

 

1 AHRI is the trade association representing manufacturers of air conditioning, heating, commercial 

refrigeration, and water heating equipment. AHRI’s 320 member companies employ approximately 

130,000 men and women in the United States. The total value of member shipments by these companies 

is over $20 billion annually. AHRI’s water heater manufacturer members account for essentially all 

residential storage water heaters and well over 90% of all residential water heaters sold and installed in 

the U.S.

2 The Administrative Procedure Act (APA), 5 U.S.C. §553, requires that “each agency shall give an 

interested person the right to petition for the issuance, amendment, or repeal of a rule.” (5 U.S.C. § 

553(e)). This right is necessary to protect interested parties from rulemakings that may be in error, that 

exceed statutory authority, or are otherwise invalid. AHRI is not asking DOE to repeal any energy 

efficiency standard that would fall within 42 U.S.C. § 6295(o)(1), but to correct an error in the final rule 

addressing the test procedure. 42 U.S.C. §6293(b)(2). 
AHRI Petition re: EERE-2011-BT-TP-0042

September 29, 2014

Page 2

6293(e). They also were not necessary to satisfy DOE’s obligation to develop a uniform 

efficiency descriptor for residential and commercial water heaters, as required by the American 

Energy Manufacturing Technical Corrections Act (AEMTCA) of 2012; they do not address any 

efficiency performance issue for water heaters; and they were not developed to respond to any 

problem that was identified by commenters during the rulemaking. AHRI and its members have 

worked diligently over the last fifty years to improve the energy efficiency of HVACR and 

Water Heating equipment. It is only out of concern for the applicability of increased efficiency 

standards through the test procedure amendment, and the alteration of industry practice and the 

scope of DOE’s regulatory authority over the past 25 years, that AHRI respectfully seeks repeal

of the referenced provisions of the test procedure final rule.

At the December 6, 2013, public hearing for this rulemaking, DOE presented data that showed 

the average rated storage volume of 19 electric water heaters was 9.4% higher than measured and 

the average rated storage volume of 44 gas water heaters was 4.8% higher than measured. From 

the perspective of the rated volume, the measured volume of the electric water heaters averaged 

about 8.6% less than the rated volume and the measured volume of the gas water heaters 

averaged about 4.6% less than the rated volume. At that meeting and in the comments we 

submitted on January 4, 2014, we provided information explaining why this data was neither 

unusual nor alarming. We noted that the relationship of measured volume and rated volume is 

addressed by the applicable national, consensus water heater standards. These standards address 

safety and other aspects of residential water heater models. The system of building code 

regulations in the U.S., along with other demands of the market, create a situation that makes 

compliance with these standards mandatory for any residential water heater intended to be sold 

and installed in the U.S. 

The standard for residential electric water heaters, UL 174 requires the following:

33 Water Capacity Test

33.1 The actual water capacity of a water heater shall be no less than 90 percent of the 

marked rated capacity.

33.2 Unless the actual capacity of a water tank is known, or is obviously 90 percent or 

more of the rated capacity, the tank capacity is to be measured by any convenient means.

The standard for residential type gas storage water heaters, American National Standard 

Z21.10.13, requires the following:

2.26 Capacities of Storage Vessels

The storage vessel capacity shall be within ± 5.0 percent of the manufacturer’s rated 

capacity.

 

3 The preface for ANSIZ21.10.1 states “This publication represents a basic standard for safe operation, 

substantial and durable construction, and acceptable performance of storage gas water heaters...”
AHRI Petition re: EERE-2011-BT-TP-0042

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Page 3

Method of Test

The storage capacity shall be determined by weighing the system when dry and empty 

and reweighing it when full or by filling the system with water, the weight of which has 

been predetermined. The capacity shall then be computed in gallons and compared with 

the manufacturer’s rated capacity.

Accordingly, the data presented by DOE is in conformance with industry practice consistent with 

the requirements of the applicable national standards. This practice has been in place for at least 

the past 50 years. If there were a real concern that this typical difference between the measured 

volume and the rated volume impacted the minimum efficiency standards or consumer 

information, that concern would have evidenced itself already. 

The requirements noted above existed in the applicable water heater standards when the first 

minimum energy factor (EF) standards for residential water heaters were established by the 

National Appliance Energy Conservation Act of 1987. We can attest with absolute certainty that 

those minimum EF standards were developed with full knowledge of the relationship of 

measured and storage volume for those water heaters. The data from DOE’s test, when properly 

considered in terms of the relationship of how the measured volume compares to the rated 

volume, reflects what is, and has been, the standard practice for residential storage water heaters 

for more than 40 years. The measured volume is lower than the rated volume. That relationship 

has not changed significantly in all those years. The test procedure established in this 

rulemaking does not change the situation at all. As DOE validated, the measured volumes of 

storage water heaters are consistently complying with the requirements of the nationally 

recognized standards. Manufacturers are not overstating the rated volume so that the minimum 

energy factor requirement for that model would be lower.

In this rulemaking, DOE clearly knew that the measured volume of residential electric water 

heaters was somewhere around 9% less than the rated volume and the measured volume of 

residential gas water heaters was somewhere around 4.5% less than the rated volume. These 

results reflect the respective requirements for electric and gas water heaters specified in the 

national consensus standards cited above. Recognizing that in an enforcement situation

manufacturers still need some margin to address test variability, the requirement of 

429.17(a)(ii)(C) will have the effect of lowering the rated volume of every electric storage water 

heater by 10% and lowering the rated volume of every gas and oil storage water heater by 5%. 

Manufacturers cannot feasibly redesign their products to make the measured volume match the 

current rated volume values. Any such redesign is precluded by the efficiency standards which 

already require several inches of insulation around the tank. A larger tank with the same amount 

of insulation will produce models that are either too wide to fit through standard doorways or too 

tall to fit into existing installation spaces. Furthermore, the cost to spend the time and money to 

redesign and test models just for a cosmetic change is prohibitive. 

The impact and change to the efficiency standards for existing products is illustrated in the table 

below, which shows: 1) the rated volume sizes that make up a manufacturer’s line of residential 
AHRI Petition re: EERE-2011-BT-TP-0042

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Page 4

water heaters; 2) the new rated volume that will be required to comply with 429.17(a)(ii)(C); 3) 

the current minimum EF requirement for each of these sizes using the respective rated volume 

values; and 4) the revised minimum EF requirement going into effect on April 16, 2015, for each 

of these sizes using the respective rated volume values. The red bolded values show the higher 

minimum standards that result from the amendments addressing the rated volume. (Note, 

recognizing DOE’s certification and enforcement provisions, the “New DOE” rated volumes are 

rounded to whole integer values.)

Gas Storage Water Heaters

Electric Storage Water Heaters

Rated Volume (G) Current Federal Minimum

EF ≥ .67 -.0019V 

Revised Federal Minimum

EF ≥ .675 -.0015V

Current New DOE Current New DOE Current New DOE

30 28 .61 .62 .63 .63

40 38 .59 .60 .62 .62

50 47 .58 .58 .60 .60

>55 >55 EF ≥ .67 -.0019V EF ≥ .8012 -.00078V

65 62 .55 .55 .75 .75

75 71 .53 .53 .74 .75

Rated Volume (G) Current Federal Minimum

EF ≥ .97 -.00132V

Revised Federal Minimum

EF ≥ .96 -.0003V 

Current New DOE Current New DOE Current New DOE

30 27 .93 .93 .95 .95

40 36 .92 .92 .95 .95

50 45 .90 .91 .95 .95

>55 >55 .97 -.00132V 2.057 -. 00113V

65 58 .88 .89 1.98 1.99

80 72 .86 .88 1.97 1.98

100 90 .84 .85 1.94 1.96

119 107 .81 .83 1.92 1.94
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Oil Storage Water Heaters

The tables above clearly illustrate that implementation of the new 429.17 (a)(ii)(C) amendment 

increases the current and upcoming revised federal minimum efficiency requirements for several 

sizes of residential storage water heaters. Furthermore, this change, if applied to the current 

standards, makes the subset of models in these sizes that are rated at the current minimum EF, 

now non-compliant with the federal standard.

The July 11, 2014, final rule established a uniform efficiency descriptor and associated test 

procedure for water heaters. Although the storage volume must be measured for purposes of the 

test, the value of the rated volume has no bearing on the calculations that determine the 

efficiency using this test procedure. The applicable provisions of AEMTCA make no mention of 

regulating the rated volume nor were any comments submitted during the rulemaking process 

raising this as an issue requiring DOE action. These amendments attached to the UED test 

procedure rule are unrelated and unnecessary issues that were generated by DOE without any 

external request or justification. In the final rule notice DOE plainly states its purpose for these 

amendments: “DOE seeks to eliminate any potential incentives for manufacturers to continue the 

current practice of exaggerating the storage volume of water heaters currently on the market by 

inflating the rated volume as compared to the actual measured volume.” If, in fact, the rated 

volume of storage water heaters was an issue, it would be a consumer disclosure or labeling 

issue, and the appropriate action would be proposal of a consumer protection or product 

advertising rule by a Federal agency responsible for such matters. It is inappropriate and outside 

the scope of DOE’s statutory authority in a regulation covering water heater efficiency test 

procedures. Furthermore, casting a practice that has been in place for more than 50 years, and 

codified in the related water heater national standards as an “exaggeration of storage volume” 

and judging manufacturers as “inflating the rated volume” indicate a bias on DOE’s part that is 

unwarranted and unrelated to DOE’s role of developing test procedures and efficiency standards.

In the final rule notice, DOE stated that the efficiency of a water heater is related to the rated 

storage volume. Thus, it is within DOE’s authority to regulate. That statement is incorrect and 

cannot be used to attempt to justify this action as within DOE’s authority. It has long been 

recognized that the rated storage volume has no direct effect on how efficiently a given model of 

water heater operates and that the volume of the storage tank cannot be used as the metric to 

represent the water heater’s hot water delivery capability. Since the very first federal efficiency 

test procedures for residential water heaters developed in the late 1970s, the measure of a storage 

Rated Volume (G) Current Federal Minimum

EF ≥ .59 -.0019V

Revised Federal Minimum

EF ≥ .68 -.0019V

Current New DOE Current New DOE Current New DOE

30 28 .53 .54 .62 .63

50 47 .50 .50 .59 .59 
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water heater’s efficiency has been energy factor (EF). The measure of the storage water heater’s 

performance, generally referred to as capacity, is the first hour rating (FHR). The first hour 

rating of a storage water heater is a combination of the volume of water in the storage tank, the 

input rate of the model, and how efficiently energy is transferred to the water in the tank. When 

the first hour rating test is conducted on a unit, the actual volume of the tank, not the rated 

volume, contributes to the final measured result. As a an example, when properly sized the hot 

water needs of a particular household may be met by a gas model that has a rated volume of 40

or 50 gallons or an electric model that has a rated volume of 50 or 65 gallons or a gas 

instantaneous (tankless) model, which has no storage volume. Additionally the residential water 

heater sizing specifications in the national model plumbing codes use the FHR, not the rated 

volume, as the basis for selecting the properly sized storage water heater for a given installation. 

This information illustrates why the first hour rating is the appropriate metric to represent a 

storage water heater’s ability to deliver hot water and how it has been used in the field for many 

years. The EF and FHR have been and continue to be the two certified values for storage water 

heaters measured by the test procedure. There have not been any issues in the field related to the 

relationship between the rated and measured volume.

It is correct that the rated storage volume is used in the equations that establish the specific EF 

minimum requirement for a given size storage water heater. However, that is the minimum 

efficiency standard that a residential storage water heater model must meet. It is not the 

efficiency of the water heater model. As illustrated by our most critical point, DOE has appeared 

to have missed that distinction. If every storage water heater model currently on the market 

today were to have its rated volume lowered to comply with the amendments in this final rule, 

there would be no change to the efficiency of any one of those models. Likewise, there would be 

no energy savings achieved by those new rated volume values. 

As we have illustrated, the value of the rated volume does influence the minimum EF standard. 

A higher rated volume does result in a lower EF requirement. The theoretical possibility that a 

rated volume would be overstated to get a lower minimum EF requirement has existed since the 

first NAECA standards went into effect in 1990. In our comments, we explained how this 

possibility has never occurred. DOE acknowledged this in the final rule notice. An examination 

of the influence of federal efficiency standards on rated volume shows an effect opposite to the 

concern of “higher” rated volume values. The following table shows the typical rated volumes 

for a manufacturer’s standard product line of gas and electric water heaters in 1990 and today. In 

a number of cases, the rated volumes have decreased. This is a direct consequence of adding 

more insulation to a model whose outside diameter cannot change for practical installation 

concerns. The remaining option is to make the diameter of the storage water tank smaller. Since 

the measured volume is smaller, compliance with the applicable standard requires the rated 

volume to be lowered. There are no rated volumes that increased. 
AHRI Petition re: EERE-2011-BT-TP-0042

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Gas Rated Volume Electric Rated Volume

1990 2014 1990 2014

30 30 30 27/30 **

40 40 40 38/40

50 50 52 47/50

65* 66 65

75 75 82 80

100*** 100

120 119

*This model size did not exist in 1990. It is a downsized version of the historical 75 gallon 

model.

**The listing of two sizes indicates that both sizes are in the product line.

***Only some manufacturers offer this model size.

Even though the other standards requirements and market influences, which made the possibility

of overstated rated volumes unrealistic, have remained the same for 40 years, DOE attempts to 

justify this punitive measure because of a desire to rule out this possibility in the future. That 

reasoning ignores the fact that the “future” minimum efficiency standards that go into effect on 

April 16, 2015, are an overwhelmingly compelling incentive to not “inflate” the rated volume of 

a residential storage water heater above 55 gallons. The minimum efficiency requirements for 

models above 55 gallons are significantly more stringent than those for models less than 55 

gallons. Furthermore, for electric storage water heaters 55 gallons or smaller the revised

minimum EF standard is the same; i.e .95, for all rated volume sizes.

Recognizing the significance of this change and the process by which it was effected, we request 

immediate action to repeal the amendments involving the certification and enforcement of rated 

volume values. AHRI will work with DOE to develop an alternative solution to the concern that 

an overstated rated volume, outside the requirements of the national consensus water heater 

standards could lower the minimum EF requirement for a particular model of storage water 

heater. As we have noted, this is fundamentally a consumer disclosure or labeling issue. 

Accordingly we believe that the Federal Trade Commission should be involved in the 

development of an alternative solution and that one option that should be considered is use of the 

FTC EnergyGuide label, which will be undergoing significant changes next year to reflect the 

ratings based on the use of the Universal Efficiency Descriptor test procedure. 

Respectively Submitted,

Frank A. Stanonik

Chief Technical Advisor