Energy Conservation Program for Consumer Products: Test Procedure for Water Heaters

SUMMARY: The Department of Energy (DOE or the Department) is amending

its test procedure for water heaters. The first-hour rating for

storage-type water heaters is revised to more accurately measure large

storage-type water heaters. Also, electric and gas-fired instantaneous

water heaters are rated at the maximum flow rate to distinguish them

from storage-type water heaters.

EFFECTIVE DATE: This rule is effective June 10, 1998.

FOR FURTHER INFORMATION CONTACT: Terry Logee, U.S. Department of

Energy, Energy Efficiency and Renewable Energy, Mail Station EE-43,

Forrestal Building, 1000 Independence Avenue, S.W., Washington, D.C.

20585-0121, Telephone (202) 586-1689, FAX (202) 586-4617,

[email protected].

Eugene Margolis, Esq., U.S. Department of Energy, Office of General

Counsel, Mail Station GC-72, Forrestal Building, 1000 Independence

Avenue, S.W., Washington, D.C. 20585-0103, Telephone (202) 586-9507,

FAX (202) 586-4116, [email protected].

SUPPLEMENTARY INFORMATION:

I. Introduction

A. Authority

B. Background

II. Discussion of Comments

A. General Comments

B. Product Specific Comments

1. Instantaneous Water Heaters

2. Storage-type Water Heaters with Rated Storage Capacities Less

than 20 Gallons

3. Definitions

4. Heat Pump Water Heaters

5. First-Hour Rating for Storage-type Water Heaters

6. Installation of Under-the-Counter and Counter-Top Water

Heaters

7. Test Conditions

8. Cost-Based Correction Factor for Fossil-Fueled Residential

Appliances

III. Procedural Requirements

A. Review Under the National Environmental Policy Act of 1969

B. Review Under Executive Order 12866, ``Regulatory Planning and

Review''

C. Review Under the Regulatory Flexibility Act of 1980

D. ``Takings'' Assessment Review

E. Federalism Review

F. Review Under the Paperwork Reduction Act

G. Review Under Executive Order 12988, ``Civil Justice Reform''

H. Review Under the Unfunded Mandates Reform Act of 1995

I. Congressional Notification

I. Introduction

A. Authority

Part B of Title III of the Energy Policy and Conservation Act, as

amended (EPCA or the Act), establishes the Energy Conservation Program

for Consumer Products other than Automobiles (Program).1 The

products currently subject to this Program include water heaters, which

are the subject of today's Final Rule.

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\1\ Part B of Title III of Energy Policy and Conservation Act,

as amended, is referred to in this Final Rule as ``EPCA'' or the

``Act.'' Part B of Title III is codified at 42 U.S.C. 6291-6309.

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Under the Act, the Program consists essentially of three parts:

testing, labeling, and the Federal energy conservation standards. The

Department, in consultation with the National Institute of Standards

and Technology (formerly the National Bureau of Standards), is required

to amend or establish test procedures as appropriate for each of the

covered products. Section 323 of EPCA, 42 U.S.C. 6293. The purpose of

the test procedures is to produce test results that measure energy

efficiency, energy use, or estimated annual operating cost of a covered

product during a representative average use cycle or period of use. The

test procedure must not be unduly burdensome to conduct. Section

323(b)(3) of EPCA, 42 U.S.C. 6293(b)(3).

Beginning 180 days after a test procedure for a product is

prescribed, no manufacturer, distributor, retailer, or private labeler

may make representations with respect to the energy use, efficiency, or

cost of energy consumed by such products, except as reflected in tests

conducted according to the DOE procedure. Section 323(c)(2) of EPCA, 42

U.S.C. 6293(c)(2).

Furthermore, DOE is required to determine to what extent, if any,

an amended test procedure would alter the measured energy efficiency or

measured energy use of any covered product as determined under the

existing test procedure. Section 323(e)(1) of EPCA, 42 U.S.C.

6293(e)(1).

B. Background

Today's Final Rule amends DOE's test procedure for water heaters by

revising the method used to determine the first-hour rating of storage-

type water heaters, adding a new rating for electric and gas-fired

instantaneous water heaters, and amending the definition of a heat pump

water heater.

On March 23, 1995, DOE published in the Federal Register (60 FR

15330) a Notice of Proposed Rule and Public Hearing on proposed

amendments to clarify the water heater test procedure and requested

data, comments, and information regarding its applicability and

workability. The Department conducted a public hearing on July 12,

1995, and a public workshop on February 12, 1997, and requested written

comments.

The proposed amendments to the water heater test procedure included

revisions to make the water heater test procedure applicable to

electric and oil-fired instantaneous water heaters; coverage for

testing storage-type water heaters with rated storage capacities less

than 20 gallons (76 liters); revision of the first-hour rating for

storage-type water heaters; amendment to the current definition for

heat pump water heater; and the addition of new definitions for heat

pump water heater storage tank, add-on heat pump water heater, integral

heat pump water heater, and solar water heater. In addition, DOE

requested comments on the adequacy of the test procedure for heat pump

water heaters regarding the use of a backup electric resistance

element(s).

II. Discussion of Comments

A. General Comments

Forty commenters submitted written comments in response to the

proposed rulemaking on water heaters. After reviewing these comments

and the comments presented during the public hearing, the Department

held a public workshop on February 12, 1997, to solicit additional

comments on the issues in the Proposed Rule. Workshop topics included

the daily hot water consumption of 64.3 gallons (243.4 liters) and the

thermostat setting of 135 deg.F (57.2 deg.C) in the existing test

procedure. The notice for the public workshop was published in the

Federal Register (62 FR 4202, January 29, 1997). Nine commenters

submitted written comments prior to and after the workshop. Those

written comments received prior to the workshop (from the Gas Appliance

Manufacturers Association [GAMA], February 12, 1997, Water Heater Test

Procedure Workshop Transcript [hereafter referred to as ``February 1997

Transcript''] at Appendix I; Electric Power Research Institute [EPRI],

February 1997 Transcript at Appendices E and J; and Controlled Energy

Corp. [CEC], February

[[Page 25997]]

1997 Transcript at Appendix H) were distributed to all participants at

the beginning of the workshop for inclusion in the workshop session.

During the rulemaking process, a number of commenters stated their

support of the EPRI recommendations on all issues. These commenters

included: Northeast Utilities Service Co., No. 11; The Dayton Power &

Light Co., No. 15; Utilities District of Western Indiana, No. 16;

National Rural Electric Coop. Assoc., No. 18; Decatur County REMC, No.

19; Pennsylvania Power & Light Co., No. 20; Central and South West

Services, Inc., No. 21; Centerior Energy, No. 22; Hawaiian Electric

Co., No. 23; Southern Company Services, Inc., No. 24; Potomac Electric

Power Co., No. 26; East Kentucky Power Cooperative, Inc., No. 34; Ohio

Edison Co., No. 39; Southern California Edison Co., No. 43; Duke Power

Co., No. 44; and Nevada Power Co., No. 45.

The following is a summary of the public comments, presented during

and after both the public hearing and the workshop, on each of the DOE

proposed amendments/revisions, and on other issues concerning the

existing test procedure.

On October 31, 1997, the comment period was reopened on the issues

of the maximum gallons (liters) per minute rating for electric and gas-

fired instantaneous water heaters and the energy factor of the heat

pump water heater storage tank. (62 FR 58923, October 31, 1997.)

B. Product Specific Comments

1. Instantaneous Water Heaters

a. Coverage of Electric and Oil-Fired Instantaneous Water Heaters.

The current test procedure does not address the testing of electric and

oil-fired instantaneous water heaters, because they are not defined in

the test procedure. In the 1995 proposed rulemaking for water heaters,

DOE proposed definitions for these two types of instantaneous water

heaters so they would be subject to the same test procedures as gas-

fired instantaneous water heaters (i.e., the first-hour rating test and

the 24-hour simulated use test).

GAMA agreed that electric and oil-fired instantaneous water heaters

should be covered in the test procedures. However, GAMA said it is

unaware of any residential oil-fired instantaneous models on the

market. (GAMA, No. 1 at 2 and February 1997 Transcript at 119.) Edison

Electric Institute (EEI), Bock Water Heaters (Bock), the Federal Trade

Commission (FTC), and the Oregon Energy Office (Oregon) also stated

that they know of no residential oil-fired instantaneous water heaters

on the market. (EEI, February 1997 Transcript at 119; Bock, February

1997 Transcript at 120; FTC, February 1997 Transcript at 120; and

Oregon, No. 51 at 3.) In response to the reopening notice of October

1997, Controlled Energy Corporation provided information on a kerosene-

fired instantaneous water heater sold by Monitor Products, Inc. (CEC,

No. 64 at 1.) The California Energy Commission (CAEC) also provided

information on one oil-fired instantaneous water heater manufactured by

Monitor Products of Princeton, NJ, which meets the definition in the

test procedure for the input BTU rating. The CAEC also informed DOE

that Monitor intends to introduce another smaller instantaneous water

heater soon, and the CAEC opposed the DOE withdrawing coverage for oil-

fired instantaneous water heaters. (CAEC, No. 68 at 1-2.)

Virginia Power stated that it does not support the testing and

rating of electric units because of the small variance in efficiency

among them. Virginia Power stated that electric units are not typically

compared to oil or gas-fired instantaneous water heaters. Virginia

Power claimed the incomparability is due to the difference in

utilization between gas-fired and electric instantaneous water heaters.

(Virginia Power, No. 50 at 2 and No. 66 at 3.) The Department

interprets this statement to mean that gas-fired models are for whole-

house applications, whereas electric models are for point-of-use

applications such as kitchen or lavatory sinks.

EPRI stated that neither the existing nor the proposed test should

be applied to instantaneous water heaters because a heating rating of

more than 150,000 Btu per hour is needed to satisfy whole-house

applications and all instantaneous water heaters for residential use

are below that heating capacity. EPRI claimed that an instantaneous

water heater should not have an efficiency rating because the

efficiency rating would falsely imply an equivalency with tank-type

water heaters. (EPRI, No. 56 at 11.)

The Oregon Energy Office suggested that an energy efficiency rating

for instantaneous water heaters is needed, and suggested that a test

procedure should be developed that would take into account the warm-up

and cool-down losses during a draw for all units (as well as the flue

and pilot light losses for gas-fired units). Oregon stated that the

procedure for instantaneous water heaters should not be the same as for

storage-type water heaters. (Oregon, No. 51 at 3.)

GAMA claimed for electric models that there are distinctions

between larger models intended for multiple points of use and smaller

models intended for a single point of use. GAMA suggested that DOE may

need to make distinctions between such units by creating separate

classes of instantaneous water heaters. (GAMA, No. 1 at 2.)

DOE believes that separate classes of electric instantaneous water

heaters would require technical data on these models, such as: (1) The

intended purpose of use; (2) the frequency of daily draws at the point

of use; (3) the average volume of each draw; and (4) the average amount

of the total daily draw. However, DOE believes that at the present

time, the development of separate classes of electric instantaneous

water heaters for residential application is not needed because, even

at the proposed maximum input power rating of 12 kW (40,944 Btu/h), an

electric instantaneous water heater can only supply a maximum of 1.06

gallons per minute (gpm) (4.01 liters per minute [L/min]) of water at a

77 deg.F (42.8 deg.C) temperature rise (from 58 deg.F to 135 deg.F

[14.4 deg.C to 57.2 deg.C]) on a continuous draw basis. DOE believes

this is far below the requirements of a whole-house application which

could range from 3-5 gallons per minute. Furthermore, the limit on the

input heating rate of electric instantaneous water heaters is not

likely to change because it is limited by the current carrying capacity

of wiring in most residential housing.

Additionally, DOE believes that the variation of the energy

efficiency of electric instantaneous water heaters would be small for

similar sized models, provided they are tested under similar conditions

because energy losses only occur during the warm-up and cool-down of

the heaters between water draws. However, test data are needed to

determine the magnitude of these losses, which are functions of the

water used during each draw and the frequency of draws. No field data

is available on the average draw rate, amount per draw, and the average

daily draw volumes for these small electric, point-of-use type

instantaneous water heaters. The daily hot water usage of 64.3 gal

(243.4 L) specified for whole-house application does not apply to these

small heating capacity electric units. Consequently, the energy

efficiency, and energy consumption cannot be determined for these units

without additional data. Therefore, DOE will not test electric

instantaneous water heaters for energy efficiency or energy consumption

until a future rulemaking when the daily hot

[[Page 25998]]

water usage data for point-of-use instantaneous water heaters are

available.

DOE did not receive any indication until after the October 1997

notice of reopening that residential oil-fired instantaneous water

heaters are on the market. DOE's belief that these water heaters were

not being sold in the United States was supported by GAMA, Bock, EEI,

the FTC, and the Oregon Energy Office. DOE believes that there is not

time for adequate public review and comment to include oil-fired

instantaneous water heaters in this rulemaking. Accordingly, DOE

withdraws its proposal to test oil-fired instantaneous water heaters in

today's Final Rule.

The Department will continue to require the testing of gas-fired

instantaneous water heaters for energy efficiency and energy

consumption because data is needed for the FTC labeling program.

b. GPM v. First-Hour Rating. In the 1995 proposed rulemaking, DOE

proposed testing for electric and oil-fired instantaneous water heaters

based on the first-hour rating currently used for gas-fired

instantaneous water heaters. This proposal would test instantaneous

water heaters in a manner equal to gas-fired storage-type water

heaters. On October 31, 1997, DOE reopened the comment period on first-

hour rating for instantaneous water heaters. In its reopening notice,

DOE proposed to revise the first-hour rating for instantaneous water

heaters from gallons per hour to a test that measures the maximum flow

rate in gallons per minute (gpm) (liters per minute [L/min]) at a

77 deg.F (42.8 deg.C) temperature rise. DOE proposed to call this

rating the maximum gpm rating.

DOE's proposed revision was in response to concerns raised by

several commenters regarding the March 1995 proposed rule. EEI, EPRI

and the Tennessee Valley Authority (TVA) considered the proposed first-

hour rating procedure for instantaneous water heaters to be

inappropriate because it would lead consumers to ``mistakenly compare

instantaneous and storage-type water heaters as being equivalent.''

They argued that a storage-type water heater can supply a large amount

of hot water during a short draw period, whereas an instantaneous water

heater may not be able to supply a similar amount of hot water because

it is limited by its heating rate. (EEI, No. 2 at 5, No. 27 at 5, and

July 12-13, 1995, Public Hearing Transcript [hereafter referred to as

July 1995 Transcript] at 22 and 27; EPRI, No. 17 at 4; and TVA, No. 14

at 2.)

During the 1997 workshop and in its written comments, EPRI

recommended a rating based on the maximum gpm flow rate at a 50 deg.F

(27.8 deg.C) temperature rise if a single rating value is used, and at

both a 50 deg.F and 77 deg.F temperature rise if two rating values are

used. EPRI stated that it prefers a rating at both a 50 deg.F and

77 deg.F temperature rise. (EPRI, No. 56 at 11.)

GAMA supported EPRI's alternative of a maximum flow rate. However,

GAMA's alternative test procedure involves adjusting the flow rate to

obtain a temperature rise of 77 deg.F in the instantaneous water

heater, and using this maximum gpm flow rate as the rating

characteristic, rather than the current first-hour rating value. GAMA

recommended that the temperature rise be the same as specified for

storage-type water heaters--that is, 77 deg.F, not 50 deg.F as

suggested by other commenters. (GAMA, No. 35 at 2.) GAMA stated it

selected a temperature rise of 77 deg.F because hot water also will be

used for machine-related applications (dishwashers and clothes washers)

that require a 135 deg.F (57.2 deg.C) temperature. (GAMA, February 1997

Transcript at 127 and 138.)

Virginia Power supports the proposal to rate instantaneous water

heaters with a maximum gpm rating. (Virginia Power, No. 42 at 2 and No.

66 at 2-3.) However, Virginia Power supports dual maximum gpm ratings,

at both 50-52 deg.F and 77 deg.F rise. Virginia Power stated that both

temperature rises are used in applications (human-contact at 110 deg.F

[43.3 deg.C] and machine use at 135 deg.F [57.2 deg.C]. Virginia

further stated that DOE's statement in the October 1997 reopening

notice that a 77 deg.F temperature rise will ensure that consumers in

cold regions of the country will have an acceptable water temperature

is inconsistent with the rationale used to establish other parameters

of the test procedure (i.e., establishing on the basis of national

average values). (Virginia Power, No. 50 at 2 and No. 66 at 3.) EEI

supported Virginia's position on this issue. (EEI, No. 65 at 1.) Oregon

stated that both a 50 deg.F and 77 deg.F would be useful in sizing a

unit properly. (Oregon, No. 51 at 3.) State Industry claimed that a

rating value based on a nominal temperature rise of 50 deg.F would not

provide consumers with information on whether the heater is capable of

delivering hot water at a 77 deg.F temperature rise. (State Industry,

February 1997 Transcript at 134.)

Based on the comments, DOE believes there is a consensus that the

current first-hour rating for instantaneous water heaters may mislead

consumers because it may overstate the capability of the instantaneous

water heater to provide a given quantity of hot water at a given

instant of time. The suggestion from GAMA, EEI, EPRI, and other

commenters to replace the first-hour rating parameter with a maximum

flow rate (gpm) over a specific temperature rise (77 deg.F [42.8 deg.C]

or 50 deg.F [27.8 deg.C]) instead of a total volume flow over one hour

is reasonable. This comparison measures the ability of instantaneous

water heaters to deliver the maximum possible amount of hot water to

the user at a specific temperature rise occurring any single moment.

Because some consumer appliances require a hot water temperature in the

135-140 deg.F (57.2-60 deg.C) range, information on the amount of flow

at a 77 deg.F rise is needed. Also, a rating value based on a nominal

temperature rise of 50 deg.F would not provide consumers with

information on whether the heater is capable of delivering hot water at

135 deg.F. Therefore, DOE believes that the maximum flow rate at the

rated energy input rate and at a temperature rise of 77 deg.F across

the water heater should be specified for rating the capability of

instantaneous water heaters to deliver hot water. Furthermore, this

maximum flow rate should be specified in place of the first-hour

rating. The Department is therefore creating a new rating for

instantaneous gas and electric water heaters using a ``maximum gpm draw

rate at 77 deg.F rise'' criterion, and renaming the criterion from

``First-Hour Rating'' to ``Maximum GPM Draw Rating'' in Sections 5.2

and 6.2 of today's Final Rule.

c. Water Temperature Rise. Regarding the outlet water temperature

for gas-fired instantaneous water heaters, the Controlled Energy

Corporation (CEC) submitted a written statement to DOE and distributed

the statement at the February 1997 workshop. CEC stated that the outlet

water temperature for an instantaneous water heater should be at 110-

115 deg.F because there is no practical domestic use for water at

135 deg.F. (CEC, February 1997 Transcript at Appendix H at 4 and No. 63

at 3.) Additionally, CEC claimed the 135 deg.F temperature specified

for storage-type water heaters is simply to increase the heat content

of the stored water and therefore is not relevant for instantaneous

water heaters. (CEC, February 1997 Transcript at Appendix H at 4.)

Group Thermo suggested that a 50 deg.F temperature rise is too low

for some cold regions of the country, and Bock suggested it is too low

for certain well water sources. EEI supported a temperature rise of

50 deg.F because there are many places like Miami and Texas with high

ground water temperatures for

[[Page 25999]]

most, if not all, of the year. EPRI supported a 50 deg.F temperature

rise because that is representative of typical human usage and a rise

of 77 deg.F because that is typical of machine usage. A.O. Smith

favored a single rating at a 77 deg.F temperature rise because it is

simpler and allows comparisons with storage-type water heaters. (Group

Thermo, February 1997 Transcript at 133 and 138; Bock, February 1997

Transcript at 132; EEI, February 1997 Transcript at 136; A.O. Smith,

February 1997 Transcript at 141; and EPRI, No. 56 at 11.)

The Department will continue to specify the test conditions for

water heater temperatures at 58 deg.F inlet (Title 10 CFR, Part 430,

Subpart B, Appendix E, Section 2.3) with a 77 deg.F rise to address (1)

machine-use applications that require a 135 deg.F water temperature for

efficient operation, and (2) the performance of a water heater in

regions of the country that may have a significantly lower supply

(inlet) temperature. Additionally, a single value of 77 deg.F rise will

reduce the test burden on manufacturers.

d. Draw Schedule. DOE did not propose any changes in the draw

schedule for instantaneous water heaters. There were several comments

addressing this issue. During the 1997 workshop, EPRI commented that

for large, whole-house, fossil-fueled instantaneous water heaters, the

losses due to warm-up and cool-down after each water draw become

significant because of the thermal mass of the water and the heat

exchanger. Also, EPRI stated the number of draws (six) in the existing

test procedure for energy factor (EF) tests is not high enough to

account for the daily total cyclical loss that occurs in practice. EPRI

claimed that in the field there are 20-50 draws per day. EPRI suggested

that tests be conducted on smaller tank types and whole-house

instantaneous water heaters to compare the difference in losses caused

by a larger number of draws throughout the day. (EPRI, February 1997

Transcript at 166, 173, and 178.)

In its written statement, CEC also requested that the draw schedule

in the 24-hour simulated use test for modulating gas-fired

instantaneous water heaters be changed from an equal number of draws at

the maximum and minimum firing rates (three at each) to 75% of the

draws at the maximum firing rate and 25% at the minimum firing rate.

CEC stated that this would reflect the fact that most of the daily hot

water consumption is at the maximum firing rate, which, CEC stated, is

when the efficiency of its heater is highest. CEC stated that the

minimum firing rate is provided for the convenience of consumers for

hand washing, etc. (CEC, February 1997 Transcript at Appendix H at 3

and No. 63 at 2.)

DOE recognizes that the number of draws will affect the energy

factor and the annual energy consumption of instantaneous water

heaters. The reason is that the warm-up and cool-down of the heat

exchanger between hot water draws will reduce the measured average

outlet temperature from the specified nominal 135 deg.F resulting in a

lower energy factor and a higher energy consumption when the outlet

temperature is adjusted back to the nominal temperature in the

calculation procedure. The decrease in outlet temperature is

proportional to the number of draws under a constant total daily draw

volume. However, DOE has no data on the amount of daily hot water usage

at the minimum or maximum firing rate for modulating gas-fired

instantaneous water heaters. Hence, there is no basis for DOE to change

the number of draws for instantaneous water heaters at either a fixed

firing rate or for modulating instantaneous water heaters at the

minimum or maximum firing rate in the 24-hour simulated use test.

Additionally, DOE needs data to substantiate any change to the number

of draws during the 24-hour simulated use test for instantaneous water

heaters because changing the number of draws is likely to reduce the

energy factor for existing units thereby requiring a modification to

the energy conservation standard for those products.

e. Energy Factor Measurement. DOE proposed a 24-hour simulated use

test for instantaneous water heaters that is exactly the same as the

24-hour simulated use test for storage-type water heaters. The 24-hour

simulated use test would determine the amount of fuel or electricity

used during a 24-hour period to heat 64.3 gallons of water to 135 deg.F

with the water being drawn in six equal draws at one-hour intervals.

Also, if the instantaneous water heater allows variable input rates,

the fuel or electricity consumed to heat 64.3 gallons of water to

135 deg.F during a 24-hour period would be determined with three draws

at the maximum flow rate and three draws at the minimum flow rate. In

the current test procedure, the recovery efficiency is calculated from

the output energy of the first draw (determined from water mass,

temperature, and specific heat) divided by the measured input energy

used during the first draw of the 24-hour simulated use test for units

with a single firing rate. For modulated units, the recovery efficiency

is the average of the two recovery efficiencies calculated on the basis

of data from the first draw (at the maximum input rate) and the fourth

draw (at the minimum input rate) of the 24-hour simulated use test.

In its comments to the 1995 proposed rulemaking, Paloma Industries,

Inc., suggested that for gas-fired instantaneous water heaters, two EF

values should be determined in the test procedure. These values would

reflect test conditions with (1) the pilot light being continuously on,

and (2) the pilot light being off except when hot water is needed. The

pilot-light-on condition is the case in which the pilot light is always

on regardless of whether there is a demand for hot water. The second

test condition is for the case in which a consumer turns the pilot

light off when hot water is not needed. Paloma claims that with its

Piezo-Elecric Ignition and Subsidiary Pilot Burner Assembly, the

consumer can manually light the pilot easily (in about 10 seconds time)

when hot water is needed. CEC concurred with Paloma. (Paloma

Industries, No. 7 at 3; CEC, February 1997 Transcript at Appendix H at

4 and No. 63 at 2.) Furthermore, CEC stated that differentiating water

heaters with pilot lights from those without is even more important

because CEC will introduce a unit in 1998 with electronic ignition.

(CEC, No. 63 at 2.)

With respect to the issue of the pilot light status between hot

water draws, GAMA recognized that turning off the pilot will reduce

energy consumption and increase the energy factor. GAMA also stated

that turning off the pilot light may not be practical for a whole-house

application. Bock expressed the same opinion. Oregon suggested that it

is possible to have two energy factors, one based on the pilot light on

between draws and one based on it being off. Oregon also recommended

that a test procedure for instantaneous water heaters should account

for warm-up, cool-down and pilot light losses. (GAMA, February 1997

Transcript at 170 and 176; Bock, February 1997 Transcript at 171;

Oregon, No. 51 at 3.)

DOE believes the suggestion to compute two energy factors is valid

only if the consumer can conveniently turn the pilot light off and on

automatically at the point of use (e.g., at the faucet or showerhead)

and if no other faucet or appliance requiring hot water is connected to

the same water heater. Neither Paolma nor CEC indicated that such an

approach was possible with their equipment although CEC has stated that

it will introduce a model with electronic ignition in 1998. DOE

believes that manual shut-off for pilot lights on instantaneous water

heaters

[[Page 26000]]

would not be practical for widespread use and energy savings.

Therefore, DOE will continue to calculate one energy factor.

2. Storage-type Water Heaters With Rated Storage Capacities Less Than

20 Gallons

In the 1995 proposed rulemaking, DOE proposed to cover storage-type

water heaters with rated storage capacitites less than 20 gallons (76

liters). This proposal was in response to a July 17, 1991, letter from

GAMA that stated that storage-type water heaters less than 20 gallons

(76 liters) are not covered by the existing test procedure.

To cover these water heaters, DOE proposed to adopt the draw rate

and the schedules in ANSI/ASHRAE Standard 118.2-1993, ``Method of

Testing for Rating Residential Water Heaters,'' to be used in the

first-hour rating test and the 24-hour simulated use test. The draw

schedules are as follows: (1) For units with rated storage less than 10

gallons (38 liters), a total volume of 9 gallons (34 liters) shall be

withdrawn, and (2) for units with rated storage greater than or equal

to 10 gallons (38 liters) but less than 20 gallons (76 liters), a total

volume of 24 gallons (91 liters) shall be withdrawn. The draw rate for

both draw schedules shall be 1.0 gallon 0.25 gallons per

minute (3.8 liters 0.95 liters per minute). DOE also requested

comments and data on its proposal to extend test procedure coverage to

storage-type water heaters of less than 20 gallons (76 liters).

Several commenters objected to one or more of these proposals.

These commenters variously cited the following reasons: (1) The

existing minimum efficiency standards are based on field applications

and usage requirements for larger volume water heaters and are

inappropriate for smaller-volume water heaters, for example, fitting

and connection losses would be unfairly treated for smaller-volume

water heaters because those losses would represent a larger percentage

of total losses; (2) it is difficult to install thermocouples and to

control flow rates in smaller-volume water heaters; (3) smaller-volume

water heaters cannot meet the efficiency requirement because they

typically are installed in confined areas, which limits the amount of

insulation used to reduce surface losses; and (4) a flow rate of 1 gpm

during water draws is too large for smaller water heaters' it would

quickly deplete the quantity of hot water in tanks of 2.5 gallons or

less. (GAMA, No. 1 at 3, No. 35 at 3, and July 1995 Transcript at 12;

EPRI, No. 17 at 2; EEI, No. 2 at 6, No. 27 at 5, and July 1995

Transcript at 28; Oregon, No. 51 at 3 and February 1997 Transcript at

164 and 195; TVA, No. 14 at 1; The Southern Company Services, Inc., No.

24 at 2; American Electric Power, No. 38 at 1; Potomac Electric Power,

No. 26 at 3; CSW, No. 4 at 2; Centerion Energy, No. 22 at 1; Nevada

Electric Power, No. 45 at 2; National Rural Electric Cooperative

Association, No. 18 at 2; Decatur County REMC, No. 19 at 1; and Dayton

Power and Light, No. 20 at 1.)

GAMA suggested that separate piping arrangement figures be used for

floor-mounted models of less than 20 gallons storage capacity. GAMA

provided the schematic drawings for its suggested changes. (GAMA, No. 1

at 6 and July 1995 Transcript 17.)

Vaughn Manufacturing Corporation claimed: (1) The number of units

is a small percentage of the total; (2) this is a utilitarian product

which is used to fit special circumstances when other alternatives are

not available; and (3) the publication of energy factors will not cause

the purchaser to choose a more efficient model to an extent that will

make a significant difference in national energy conservation. (Vaughn,

No. 31 at 2.)

However, AGA believed that the large number of such heaters sold

justifies some measurement that could be used for a minimum standard.

(AGA, February 1997 Transcript at 184-185.) GAMA proposed running only

a stand-by loss test for the measurement, and EPRI proposed to base

this measurement on the maximum stand-by loss without considering daily

water consumption. GAMA argued that any standard would have to be

connected to some level of daily consumption. The FTC pointed out that

if the test procedure covers these products, they would have to be

labeled, and the label has to contain a value for energy consumption.

In its written comments, GAMA stated that the applicable maximum hourly

stand-by loss requirement in ASHRAE 90A-1980 was 43W. GAMA asserted

that because the ASHRAE loss was based on an 80 deg.F temperature

difference, the DOE maximum loss rate should be 36.3W, based on the

67.5 deg.F temperature difference for the DOE test. GAMA concluded that

the DOE proposal for the 24-hour simulated use test should be scrapped

and that only an hourly stand-by loss should be measured by the test

procedure. (GAMA, No. 35 at 4 and February 1997 Transcript at 165 and

185-186; EPRI, February 1997 Transcript at 183-184; and FTC, February

1997 Transcript at 186.) This proposal was not supported by Virginia

Power, who claimed that losses for fittings were greater for small

tanks and that specialized uses for these tanks may limit the kinds of

modifications leading to improved efficiency. Oregon supported the

stand-by loss proposal and added that heaters with capacity equal to or

less than 2 gallons (7.6 liters) be exempt from coverage and that all

water heaters less than 20 gallons (76 liters) be exempt from the

Energy Guide labeling requirement. EPRI expressed general support for

GAMA's proposal, but suggested that a combination of stand-by loss and

recovery efficiency rather than a single energy efficiency term be used

to determine the energy standard for small water heaters. (Virginia

Power, No. 42 at 3; Oregon, No. 51 at 3 and February 1997 Transcript at

164 and 195; EPRI, No. 56 at 5 and February 1997 Transcript at 164,

183, and 188 and at Appendix J at 2.)

Although the Department believes the stand-by loss measurement for

water heaters less than 20 gallons (76 liters) proposed by GAMA and

EPRI may be feasible, DOE will reserve consideration of this proposal

for a future revision of the test procedure. The reasons for this

decision are: (1) Absence of data to determine the appropriate daily

hot water consumption, and (2) DOE's need to develop and evaluate the

stand-by loss procedure. Therefore, DOE is withdrawing its proposal in

today's Final Rule.

3. Definitions

In the 1995 proposed rule making, DOE solicited comments on the

addition to the test procedure of definitions of a heat pump water

heater storage tank and a solar water heater. DOE also proposed to

revise the definition of a heat pump water heater to specify two types,

an integral heat pump water heater and an add-on heat pump water

heater.

The following discussion ensued:

(i) Solar Water Heater. GAMA stated that it did not understand the

purpose or intent of the expanded definitions or the need to define

``solar water heaters'' for the test procedure. GAMA suggested that the

requirement that a solar water heater obtain 50% of its annual heating

energy from the sun is not a definitive criterion because a solar water

heater with less than 50% of its input energy from the sun is still a

solar water heater. (GAMA, July 1995 Transcript at 15 and No. 1 at 5.)

(ii) Heat Pump Water Heater Storage Tank. During the February 1997

workshop, GAMA proposed that a 50-gallon tank standardized with respect

to the energy factor is adequate and should be used to test any add-on

heat pump water heater sold without a tank by its manufacturer. (The

existing DOE test

[[Page 26001]]

procedure specifies a 47-gallon tank meeting the minimum standard

energy factor or not greater than .02 EF above the minimum.) GAMA

objected to the Department's proposal for a special heat pump water

heater storage tank.

EPRI objected to the inclusion of a special heat pump water heater

storage tank, and proposed that an add-on heat pump water heater be

tested with a standard 50-gallon tank as required under the existing

DOE test procedure. EPRI further stated that there are no storage tanks

labeled and designed for use exclusively with heat pump water heaters.

All other commenters, such as the Oregon Energy Office and Virginia

Power, agreed with GAMA's and EPRI's proposals for a standard 50-gallon

tank. The Oregon Energy Office called for a revision of the original

definition. (GAMA, February 1997 Transcript at 229; EPRI, No. 17 at 5

and February 1997 Transcript at 227; Oregon, No. 51 at 6; Virginia

Power, No. 50 at 4.)

(iii) Add-on Heat Pump Water Heaters. EEI expressed concerns about

the definition of add-on heat pump water heaters. EEI and EPRI claimed

the definition is inappropriate and should not be adopted. They stated

that add-on heat pump water heaters are designed to work with any

electric water heater tank and that some are designed to work with any

tank. EPRI claimed the new definition limits the availability of tanks

for use with add-on heat pump water heaters. EPRI believes that this

new definition would increase the cost. Further, EEI found that this

definition is ill-advised, because new tanks of essentially identical

construction must meet two definitions, thus creating confusion and

potentially increasing the cost of heat pump water heaters. (EEI, No. 2

at 7, and No. 27 at 7; EPRI, No. 17 at 5.)

Virginia Power proposed deleting ``heat pump'' from the last line

of the definition. (Virginia Power, No. 50 at 4.)

Vaughn Manufacturing Corp. commented that the addition of more than

one category of heat pump water heaters, or even solar water heaters,

will add to the confusion because it may lead consumers to compare test

results of dissimilar types of water heaters. (Vaughn, No. 31 at 4.)

(iv) Integral Heat Pump Water Heaters. GAMA suggested that, instead

of the 1995 DOE proposed definitions of ``integral heat pump water

heaters'' and ``add-on heat pump water heaters,'' the respective

definitions should be ``heat pump water heaters with tanks'' and ``heat

pump water heaters without tanks''.

Also, GAMA objected to the term ``integral heat pump water

heaters'' because it implies that the heat pump is structurally

integrated with a tank, whereas in reality, the heat pump and the tank

can be physically separated, but are usually sold by the manufacturer

as a packaged unit. (GAMA, February 1997 Transcript at 230.)

Virginia Power proposed deleting the definition of ``integral heat

pump water heater.'' (Virginia Power, No. 50 at 4.)

(v) Proposed Revisions. DOE responded to these comments in the

October 1997 reopening notice. In this notice, DOE proposed the

following revisions:

Withdraw the definition of solar water heaters.

Withdraw the proposal for heat pump water heater storage

tanks for testing with an add-on heat pump water heater.

Delete the definition of integral heat pump water heaters.

Replace the definition of ``integral heat pump water

heaters'' with the definition, ``Heat pump water heater with storage

tank means an air-to-water heat pump sold by the manufacturer with an

insulated storage tank as a packaged unit. The tank may be integral

with or separated from the heat pump.''

Replace the definition of ``add-on heat pump water

heater'' with the definition, ``Heat pump water heater without storage

tank (also called add-on heat pump water heater) means an air-to-water

heat pump designed for use with a storage-type water heater or with a

storage tank that is not specified or supplied by the manufacturer.''

EEI, Virginia Power, and GAMA supported DOE's proposed definitional

changes in the October 1997 notice of reopening. (EEI, No. 65 at 1;

Virginia Power, No. 66 at 4; and GAMA, No. 67 at 1.) No commenter took

issue with the proposed definitional changes.

Therefore, DOE is adopting in this Final Rule the proposed revision

as stated above.

4. Heat Pump Water Heaters

a. Back-up Electric Resistance Heating. In the Proposed Rule, the

Department requested comments on the adequacy of the existing test

procedure regarding back-up electric heating elements for heat pump

water heaters because the current test setup and parameters may not

represent operating conditions requiring the resistance element(s) to

be activated. The existing procedure does not account for energy used

by these elements because most heat pump water heaters are capable of

meeting the test draw requirements of the 24-hour simulated use test

for the energy factor and, therefore, the back-up electric resistance

heating element(s) is not activated.

GAMA stated that the current draw schedule is such that the back-up

electric resistance element(s) does not turn on during testing.

Although GAMA concluded from tests conducted at Intertek Testing

Service (ITS) that changing the current draw schedule by increasing the

volume of water withdrawn will not activate the elements, it still

argued that in residential applications, a significant percentage of

the energy for water heating (15-20%) comes from the back-up resistance

element(s). GAMA asserted that this energy should be included in

determining the annual energy consumption of the heat pump water

heater. This view is shared by the Southern Company Services (SCS).

(GAMA, No. 1 at 5, No. 35 at 5, July 1995 Transcript at 16, and

February 1997 Transcript at 241; and SCS, No. 24 at 2.) Vaughn

Manufacturing Corporation claimed that the one-hour recovery between

the six small draws prejudices the test procedure in favor of heat pump

water heaters. Furthermore, Vaughn claimed, this test profile is not

based on a representative average use cycle. (Vaughn, No. 31 at 3.)

Georgia Power recommended that the draw schedule continue to stipulate

10.7 gallons per draw for each hour. (Georgia Power, No. 54 at 2.)

GAMA recommended adding some electrical energy to the annual energy

consumption calculation but GAMA did not recommend a specific amount of

energy. GAMA claimed that this electrical energy was necessary because

no resistance heating was measured during tests of heat pump water

heaters using the DOE test procedure and GAMA claims that it is well

accepted that heat pump water heaters use backup resistance heating

during periods of heavy draws. (GAMA, No. 57 at 2 and February 1997

Transcript at 240-260.) The recommendation was supported by AGA and the

Oregon Energy Office. (AGA, February 1997 Transcript at 254 and 263;

Oregon, February 1997 Transcript at 248, 250, and 255; and Oregon, No.

51 at 5.)

However, EPRI claimed that its data shows that less than 10 percent

of the energy consumption for water heating with heat pumps actually

comes from the back-up resistance elements for customers who use about

64 gallons of hot water per day. EPRI argued that it would be improper

to apply a correction factor to compensate for resistance elements that

do not activate during average test conditions. Moreover, EPRI added

that if a correction factor is applied to heat pump water heaters,

[[Page 26002]]

then correction factors due to regional conditions would need to be

applied to all types of water heaters. Based on these reasons, EPRI is

opposed to the recommendation by GAMA. (EPRI, No. 56 at 2, February

Transcript at 239, 248, 257 and 264 and at Appendix J at 2.) Virginia

Power agreed with EPRI's comments. (Virginia Power, No. 50 at 4, and

February 1997 Transcript at 249 and 258.)

Other opponents to GAMA's recommendation included Abrams and

Associates, who commented that the purpose of the test procedures is to

rate water heaters for comparison purposes rather than to reflect

actual household applications. Lawrence Berkeley National Laboratory

(LBNL) stated that heat pump water heaters do not need a separate test

procedure to account for backup resistance heating because of their

insignificant market share and greater efficiency. EEI commented that

to activate the heating elements would require a draw in excess of 50

gallons, which is not realistic. AIL Research stated that no correction

factor should be used until data becomes available. (Abrams, February

1997 Transcript at 260; LBNL, February 1997 Transcript at 252; EEI,

February 1997 Transcript at 255; and AIL, February 1997 Transcript at

261-264.)

The Department believes that the 24-hour simulated use test for the

energy factor must be based on average test conditions that also apply

to other water heaters of comparable size and use so that all storage-

type water heaters are tested and rated on a consistent and uniform

basis. Furthermore, DOE notes that based on test data submitted by

GAMA, the back-up heating elements for heat pump water heaters will not

activate when the volume of hot water drawn is changed from 10.7

gallons to a more severe 21.4 gallons per draw during two of the six

draws of the 24-hour simulated use test. The Department believes that

any single draw in the draw schedule greater than the 21.4 gallons per

draw (as tested) would not be considered as an average use pattern.

Because the test procedure is for comparison purposes and is not

intended to take into account all potential field use patterns (such as

the draw-down of the storage tank), DOE considers that a revision to

the current draw schedule of 10.7 gallons per draw for the six draws in

the 24-hour simulated use test (for example, stipulating 21.4 gallons

per draw for two of the six draws) is not necessary because it will not

change the result. Furthermore, there is no agreement on an average

percent of the annual energy consumption that comes from the resistance

heating elements. Therefore, the Department concludes that applying a

correction to the energy factor and/or annual energy consumption of the

heat pump water heater to account for the energy used by the resistance

elements that do not activate during testing is unwarranted and will

not be included in today's Final Rule.

b. Installation Requirements. The installation requirements in

Section 4.1 of Appendix E of the current test procedure state that a

heat pump water heater without a manufacturer-supplied storage tank

shall be connected to the storage tank in accordance with the

manufacturer's instructions. The requirements further state, ``If

installation materials are not provided by the heat pump manufacturer,

use uninsulated 8 foot (2.44 m) long connecting hoses, having an inside

diameter of 5/8 inch (1.6 cm).'' The intent of this requirement is to

specify a uniform test setup for those units that do not include

manufacturer's instructions. DOE asked for comments on this issue.

EPRI commented that the term ``installation materials'' in this

context is unclear. EPRI suggested changing ``installation materials''

to a more descriptive term because most manufacturers of add-on heat

pump water heaters, or any other type of water heater, do not provide

the plumbing hardware and should not be penalized for not doing so.

(EPRI, No. 17 attached report at 6.) American Electric Power claimed

that the installation requriements were vague. (American Electric, No.

38 at 1.) Oregon suggested that in cases in which manufacturers do not

include instructions, the test procedure should be performed using

insulated hoses of sufficient length and size to properly mount the

heat pump unit relative to the storage tank. (Oregon, No. 51 at 6.)

To make the wording clear, DOE is revising the text in section 4.1

of Appendix E from ``installation materials'' to ``installation

instructions'' as suggested by EPRI. DOE disagrees with Oregon's

comment because in most residences, the hot water pipes usually are not

insulated. DOE believes that the 8-foot hose is adequate to make the

heat-pump-to-water-heater connection and ensure that the heat loss from

the uninsulated hose is equal for all add-on heat pump water heaters

that do not have manufacturers' installation instructions.

c. Heat from the Ambient Air. The current and proposed test

procedures use the same test conditions and test procedures for oil-

fired, electric and heat pump water heaters. Vaughn claimed that

because the DOE test procedure does not account for heat removed from

the ambient air, the procedure favors heat pump water heaters. (Vaughn,

No. 31 at 3.)

The Department has considered this topic and has concluded that the

interactions between heat pump water heaters and the building

environment are extremely complex and difficult to measure.

Furthermore, in some cases, heat pump water heaters may be installed

outside the building, in which case the heat removed from the ambient

air is free and does not need to be counted. For these reasons, DOE

will address building and heat pump interactions in a future

rulemaking.

5. First-Hour Rating for Storage-type Water Heaters

In the 1995 proposed rulemaking, DOE proposed a revised test

procedure for the first-hour rating for storage-type water heaters. The

proposed revision specifies the start of a first draw at the beginning

of the one-hour period, when the average tank temperature is at the

specified limit of 135 deg.F 5 deg.F (57.2 deg.C

2.8 deg.C) and all the thermostats are satisfied. The

first draw is terminated when the outlet water temperature decreases by

25 deg.F (13.9 deg.C) below the maximum outlet temperature recorded

during the draw. Successive draws are initiated when the uppermost

thermostat is satisfied following a tank recovery, and ended when the

outlet water temperature decreases by 25 deg.F (13.9 deg.C) below the

maximum outlet temperature recorded during each particular draw.

At the end of the one-hour period, a final draw is initiated if no

draw is in progress. This draw is terminated when the outlet water

temperature decreases to the value used to terminate the draw that was

completed before this final draw. If a draw is in progress at the end

of the one-hour period, this draw is continued until the outlet water

temperature decreases by 25 deg.F (13.9 deg.C) below the maximum outlet

temperature recorded during this draw. A temperature correction factor

is applied to the last draw. The correction factor is a quotient in

which the numerator is the average delivered water temperature of the

last draw minus the minimum water temperature of the next-to-last draw

and the denominator is the average delivered water temperature of the

next-to-last draw minus the minimum water temperature of the next-to-

last draw. The correction factor corrects for any significant reduction

in energy content of the draw due to a lower average outlet water

temperature over the draw

[[Page 26003]]

than those obtained during the earlier draws.

Thermally compensating dip tubes and integral mixing valves result

in higher first-hour ratings. DOE did not propose to apply a correction

factor to water heaters employing these features because the Department

was unaware of the existence of these features on currently

manufactured water heaters. However, EPRI, EEI, and Nevada Power

Company stated that because at least one U.S. manufacturer has

purchased the right to manufacture and sell the equivalent of an

``internal mixing'' product, DOE should develop a procedure that

accounts for differences in hot water delivery temperatures. (EEI, No.

27 at 5; EPRI, No. 17 at 12; and Nevada Power Company, No. 45 at 3.)

Southern Company Services (SCS) argued that specifications for mixing

valves (similar to internal mixing) are not relevant to efficiency and

the use of mixing valves should not be restricted. Furthermore, SCS

supported the test procedure proposed by Dr. Carl Hiller of EPRI, which

it claimed would not be affected by mixing valves. (SCS, No. 24 at 2.)

EEI and EPRI commented that DOE's proposed first-hour rating

procedure, while an improvement over the current (1991 Final Rule) and

previous (1978) DOE procedures, is still flawed and should not be

implemented. Both EEI and EPRI based their comments on the analysis of

the DOE proposed procedure by Dr. Carl Hiller of EPRI. (EEI, No. 2 at

2, No. 27 at 2, and July 1995 Transcript at 22; and EPRI, No. 17

attached report at 2.)

Dr. Hiller commented that the DOE proposed procedure is based on

unrealistic water consumption behavioral patterns, and bears little

relevance to the sizing of hot water systems. Dr. Hiller stated that

the procedure gives misleadingly high ratings to units having a high

heat input rate, thus penalizing electric systems and systems with

larger tanks. Dr. Hiller suggested that the entire proposed procedure

should be abandoned and replaced with an alternative developed by EPRI.

(EPRI, No. 17 at 9 and 13.)

Specifically, Dr. Hiller claimed that the DOE proposed first-hour

rating procedure for storage-type water heaters is characterized by the

following: (1) It penalizes large tanks because the draw rate of 3 gpm

causes the draws to take longer for larger tanks, thus limiting useful

reheat time; (2) the temperature correction factor applied to the last

draw is cumbersome; (3) the draw at the end of the one-hour test

results in a variable test time; (4) depending on the thermostat

setting and behavior, two similar tanks may show dramatic differences

in their first-hour ratings; (5) the one-hour time period in the

procedure is arbitrary and relatively irrelevant to water heating

system sizing; and (6) the procedure fails to account for the energy

content of water delivered at different temperatures during the draws.

(EPRI, No. 17 at 9-13.)

Dr. Hiller proposed three EPRI alternatives to DOE's first-hour

rating procedure. The first alternative calculates first-hour rating as

the sum of (1) the volume of water from an initial draw (multiplied by

a factor to correct to a uniform delivery temperature of 110 deg.F

(43.3 deg.C) and (2) the maximum useful reheat volume (water is heated

to 110 deg.F [43.3 deg.C]) at the rated energy input between the end of

the first recovery (after the first draw) and the end of a specified

reheat time period. This EPRI proposal uses a calculation to determine

the maximum useful reheat volume during the specific reheat period;

EPRI notes that the maximum useful reheat volume could also be

determined with actual draws. In this proposal, EPRI advocates a reheat

period of 35-45 minutes instead of one hour. (EPRI, No. 17 at 13.)

The second EPRI alternative, proposed by Dr. Hiller at the February

1997 workshop, bases tank sizing on a graph of the way hot water is

actually used over a specific time period together with graphical

representations of hot water delivery capability (a stepwise function

versus time due to reheat delay) for various water heaters. The water

heater size is found by overlaying the two graphs of hot water delivery

capability and hot water consumption requirement. EPRI provided

examples of data for several tank sizes for hot water delivered not

exceeding once per day, once per week and once per month derived from a

2\1/2\ year EPRI field study at 14 metered sites with electric storage-

type water heaters. (EPRI, No. 56 at 6, and February 1997 Transcript at

Appendix J at 4-10.)

In its comments after the February 1997 workshop, EPRI proposed a

third alternative first-hour rating procedure, which modified its first

proposal. In this procedure, hot water is drawn initially and during

four reheat cycles. Data from the five corresponding draws (stepwise in

form as in the second alternative) are used to establish a graphical

representation of hot water availability versus time, including the

reheat time delay between the first draw after recovery (on the basis

of the cut-out of the uppermost thermostat) and the subsequent draw.

From these measurements, the actual first draw volume available and the

actual average reheat rate of the system are determined. After the

first reheat is completed, a linear calculation is performed to

estimate the number of additional gallons that can be produced based on

the average reheat rate. Then the ``minimum'' maximum water

availability curve is calculated. The hot water delivery rating from

the graph is determined based on the minimum hot water availability

curve together with a ``critical design time interval'' of 35 minutes.

EPRI claimed that this procedure accounts for the first draw volume and

the reheat rate, as well as the reheat time delay between the hot water

run-out after the first draw and the completion of the recovery (on the

basis of the cut-out of the uppermost thermostat). EPRI claimed that

this procedure is better than the DOE proposed procedure because the

reheat delay time is accounted for. The third alternative differs from

the first alternative primarily because the third alternative involves

four cycles of reheating, and the water temperature at the top of the

tank after recovery is at 135 deg.F (57.2 deg.C) instead of 110 deg.F

(43.3 deg.C). (EPRI, No. 56 attached report at 11-12.)

This proposal includes an optional method that permits

manufacturers to list the first draw as the first draw rating because

the 35-minute hot water delivery rating is typically at or near the

first draw capability of the tank. This avoids the need to perform the

four reheats and five draws. (EPRI, No. 56 attached report at 13.)

Virginia Power and American Electric Power (AEP) also stated their

opposition to the DOE first-hour rating and their support of a maximum

first draw rating. Virginia Power claimed that the maximum first draw

rating more accurately represents typical consumer action. (Virginia

Power, No. 50 at 2; AEP, No. 53 at 1.)

Rheem Manufacturing claimed the first-hour rating is seldom used by

consumers in purchasing water heaters. (Rheem, February 1997 Transcript

at 154-155.)

Georgia Power claimed that the first-hour rating is biased toward

gas-fired water heaters. Georgia Power proposed an alternative method

which involves checking the temperature in the top of the tank

periodically after the first draw is complete. When the temperature is

above the minimum setpoint temperature, a second draw should begin. It

claimed that this procedure reflects the way a consumer would use hot

water after a run-out. (Georgia Power, No. 54 at 1.)

GAMA stated that it does not support EPRI's alternative first-hour

rating

[[Page 26004]]

procedures. GAMA claimed that the current and proposed DOE test

procedure, in which water is drawn from a tank full of heated water and

then subsequent draws are made each time the tank returns to the

setpoint temperature within an hour, is an appropriate way to evaluate

a water heater's capability to provide heated water. GAMA stated that

the DOE procedure may require some modifications and corrections in the

calculations, but GAMA did not believe it is necessary to rewrite the

entire first-hour rating procedure (as suggested by EPRI). (GAMA, No. 1

at 2, and No. 35 at 2, and July 1995 Transcript at 10.)

GAMA claimed the 1990 procedure gives a first-hour rating volume

that may be smaller than the first draw volume for larger tanks. GAMA

presented the results of tests conducted by its water heater

manufacturer members that compared representative models of gas-fired

and electric water heaters. The test results were compiled from both

the current test procedure and the 1995 DOE proposed first-hour rating

test procedure. The data show that the proposed procedure does provide

a first-hour rating that reflects a combination of the water heater's

storage capacity and recovery rate. In a written submittal at the

February 1997 workshop, GAMA presented additional test results

conducted by Intertek Testing Service on water heaters tested in the

GAMA efficiency certification program. The data showed that 53 gas-

fired water heaters (with storage capacities of 30-50 gallons) were

tested, and the difference between the first-hour rating using the

proposed procedure and the first-hour rating based on the current

procedure varied from -0.2 gallons to 8.0 gallons with a standard

deviation for each tank volume class tested of 3.7-6.0 gallons. The

data also showed that 51 electric water heaters (with storage

capacities of 30-82 gallons) were tested, and the differences in rating

value were from 3.7 gallons to 5.5 gallons with a standard deviation

for each tank volume class tested of 2.0-5.8 gallons. GAMA believed

that the data is indicative of a general trend and that it does support

the use of the proposed first-hour rating test procedure. (GAMA, No. 1

at 2, No. 35 at 2, and February 1997 Transcript at 91-92 and at

Appendix I at 1-2.)

GAMA, in the same written submittal at the February 1997 workshop,

claimed DOE should provide an alternative conservative calculation for

the first-hour rating. GAMA's suggested calculations are based on 1995

and 1996 data from GAMA's efficiency certification program. The 1996

data show that the volume of the first draw compared to the rated

volume is about 0.85 for gas-fired water heaters and 0.78-0.85 for

electric water heaters. GAMA proposed three calculations for first-hour

rating: (1) For gas-fired water heaters, the first-hour rating equals

0.8 of the tank volume plus an energy-based correction factor; (2) for

dual-element electric water heaters, the first-hour rating equals 0.75

of the tank volume plus an energy-based correction factor; and (3) for

a single element electric water heater, the first-hour rating equals

0.75 of the volume. GAMA claimed these calculations give conservative

results. (GAMA, February 1997 Transcript at Appendix I at 1-2.)

GAMA, in a later submittal following the February 1997 workshop,

stated that its proposed optional first-hour calculation for electric

water heaters should be modified to provide a more accurate first-hour

value for larger volume models. It stated that the original calculation

leads to an assumption that no recovery will occur for 24 minutes with

an 80-gallon tank. GAMA stated that because the lower heating element

turns on in 2-5 minutes into the first-hour rating test in all electric

water heaters, GAMA decided to modify the volume-related correction

factor for dual-element electric water heaters to reflect this. (GAMA,

No. 57 at 1.)

Supporters of the DOE proposal for determining the first-hour

rating include the AGA, which finds it useful in determining the proper

size of a water heater, stating that proper sizing is important for

energy conservation, customer satisfaction and safety. (AGA, No. 55 at

1.) The Oregon Energy Office recommended DOE adopt its 1995 proposal

and not adopt any part of the EPRI proposals because Oregon claimed

EPRI put too much weight on the first draw volume, thus promoting

larger tanks. (Oregon Energy Office, No. 51 at 2 and February 1997

Transcript at 110-112.) In a statement submitted after the February

1997 workshop, Battelle Columbus presented some experimental data and

analysis of a 35,500 Btu/h, 50-gallon gas-fired water heater. Battelle

presented data to show that the test water heater was able to satisfy

the ``once a month'' draw schedules based on the EPRI field tests of 15

actual households. Battelle claimed that the test water heater could

meet 12 of the 15 household hot water loads with a delivery temperature

above 110 deg.F. Battelle claimed the data showed that the DOE first-

hour rating procedure is a good predictor of water heater performance.

(Battelle, No. 58 at 1.)

George Kusterer of Bock Water Heaters stated that the information

relating to EPRI's alternate first-hour rating method is inconclusive

and recommended it not be accepted by DOE. Bock also claimed that a

first-hour rating based only on the first draw will not work. (Bock,

February 1997 Transcript at 146, 151 and 153.)

In response to EPRI's comments on the effect of the draw rate, DOE

does not agree that a 3 gpm draw rate will result in a shorter reheat

time for larger tanks. This is due to the fact that, for most electric

water heaters, the bottom element will turn on within 5 minutes into

the first draw. Also, a larger draw rate and a longer reheat time may

not increase the total amount of hot water drawn because the heat input

rate and not the draw rate will determine whether a tank can recover to

a minimum temperature of 110 deg.F. This recovery capability is the

reason that the size of the storage tank is not the only criterion for

first-hour rating.

Tank size is critical for simultaneous water usage, but tank

recovery rate, either by a greater input rate or by dual--heating

element design, could prove critical during times of consecutive hot

water usages. While it is true that a consumer will not wait for the

tank water temperature to reach 135 deg.F or the thermostat to cut out

before turning on the hot water faucet, the one-hour rating does

provide a simple and easy to understand indication of the combined

effects of tank size and recovery rate within a reasonable time frame

where heavy use of hot water may occur (for example, during the morning

hours). It is also a definitive procedure for manufacturers to use for

labeling but it is not necessarily an appropriate criterion for tank

sizing since that depends on consumer behavior and uses of hot water.

The temperature correction factor is used to adjust the volume of

the last draw to account for the possible lower heat content of the

last draw than those earlier draws with fully heated water. DOE has

created the temperature correction factor as a simple arithmetic

temperature ratio using temperature data that has already been measured

during the test. DOE realizes that the temperature of the last draw may

be at a lower temperature than those of earlier draws.

DOE does not believe that due to the imposition of the last draw at

the one-hour mark, two similar tanks, one at 111 deg.F and the other at

109 deg.F, will result in a large difference in the amount of total

volume drawn. The temperature correction factor is specifically applied

to prevent that from happening. For example, assuming that the whole

tank of water at 111 deg.F is drawn, the

[[Page 26005]]

temperature ratio, (111-110)/(130-110) = 0.05, will add only 5% of the

last draw volume to the total volume drawn at the one-hour mark. (For

illustration purposes, the maximum outlet temperature is assumed to be

135 deg.F and the average outlet water temperature during a regular--

not the imposed--draw is assumed to be 130 deg.F.) DOE believes this

difference of 5% of the volume of the tank is acceptable for grouping

models of storage-type water heaters.

There were claims that the DOE test period of one hour is too long.

The one-hour time period is related to a similar period of high water

consumption in most residences. Although the EPRI data indicates a

shorter time, DOE believes that more data is necessary to establish a

national average pattern of use, and DOE does not believe that a

reduction of 25 minutes in test time, as suggested by EPRI, is merited.

There were no comments from manufacturers or GAMA that the shorter test

time was desirable. Rather, Darrell Paul, EEI, Bock, and Group Thermo

stated that people tend to adjust their hot water use pattern during

high consumption periods to account for short periods without hot

water. (Battelle Columbus, February 1997 Transcript at 47; EEI,

February 1997 Transcript at 49; Bock, February 1997 Transcript at 52;

Group Thermo, February 1997 Transcript at 53.)

Regarding the comment that a final draw results in a variable

testing time, certainly the imposition of a final draw extends the test

period beyond one hour. However, the procedure requires the cessation

of input energy at the one-hour mark. Therefore, DOE believes this is

an equitable way to account for all the usable heat energy input to the

water heater within the one-hour time frame.

DOE does not believe that a correction factor for hot water tanks

with induced interim mixing will improve the accuracy of the test

procedure enough to warrant its inclusion. DOE does agree that a

temperature correction factor should be applied to the water drawn

during each of the draws if a thermally compensating dip tube or an

internal mixing device is used. However, at the present time there is

no water heater that employs a mixing valve or thermally compensating

dip tube during its normal operation. One design that does employ a

mixing device is a special application for utility demand-side

management in which higher temperature hot water is heated and stored

during periods of low electricity demand. However, such a tank can be

tested under the proposed DOE test. Therefore, a correction factor for

induced internal mixing is not needed at this time.

The Department reviewed and evaluated two of the proposals

presented by EPRI (the second and the third, the latter of which is

EPRI's modification of its first alternative). DOE considers that the

second proposal, as stated by EPRI, is still in the development stage.

DOE believes that when completely developed, the method may be included

and used, in graphical or tabulated forms, in a design manual for use

by designers to size the hot water tank for the needs of a particular

customer. However, to adopt the procedure for a single number rating

purpose would require the development of, and agreement by all

concerned parties to, an average national utilization curve to be used

in conjunction with EPRI's hot water delivery capability graphs for

various models of water heaters. The Department believes that prospect

will not be feasible in the near future. Furthermore, the Department

believes that EPRI's third proposal should not be adopted. The reasons

are (1) the procedure puts more weight on the first draw, which would

tend to encourage the use of larger tanks; (2) the hot water produced

during the recovery period is not included, even though it is available

at the end of recovery; (3) the proposed four reheat cycles may require

a very long test time, especially for larger electric tanks; (4) for

water heaters with a lower heat input rate, the subsequent draw rate,

which provides continuous 135 deg.F (heated up from the 58 deg.F inlet

condition) water and is calculated on the basis of the reheat rate,

will be much lower; and (5) the procedure, and any modification to it,

has not been tested.

The Department has decided not to adopt the optional calculation

procedure proposed by GAMA. The Department checked the optional

calculation procedure against data published in the GAMA directory and

found that the results for first hour rating varied among electric,

gas-and oil-fired water heaters. Furthermore, the coefficients proposed

by GAMA were based on the current test procedure for first hour rating.

The Department believes that the optional calculation may have merit,

but the coefficients need to be based on the first hour rating in this

Final Rule. For these reasons, the Department has decided to adopt the

1995 proposed procedure for first-hour rating in today's Final Rule.

6. Installation of Under-the-Counter and Counter-Top Water Heaters

The installation requirements in section 4 of Appendix E of the

proposed test procedure do not distinguish under-the-counter water

heaters from counter-top water heaters. GAMA recommended these be

addressed separately because they are intended for different

installations. GAMA indicated that because the water connections for

counter-top models are within the water heater jacket, they can be

installed flush to the back wall, and that this is not true for under-

the-counter models. GAMA also recommended that separate piping

arrangements be provided for floor-mounted water heaters with storage

capacities less than 20 gallons. GAMA submitted four figures

illustrating these configurations. (GAMA, July 1995 Transcript at 17

and No. 1 at 6.) Intertek Testing Services confirmed that GAMA's

suggested changes are consistent with the normal practice in testing

these types of models. Intertek further furnished piping schematics for

those under-the-counter models that have a side inlet port and a top

center outlet port. (Intertek, No. 62 at 1.)

The Department supports these proposals. The Department understands

that if a counter-top model is installed with the back surface of the

water heater jacket flush against the wall, the heat loss through the

back surface will be different from an installation in which the back

surface is exposed directly to the ambient air. DOE also understands

that for under-the-counter models, the limitation of space under the

counter necessitates a short piping connection, which should be

reflected in the installation requirement. Therefore, the installation

figures for piping connections for under-the-counter and counter-top

water heaters as provided by GAMA and Intertek are included in today's

Final Rule (as Figures 3, 4, 5, 6, 7A, and 7B in Appendix E). Sections

4.1 and 4.3 of Appendix E are revised to indicate these new figures and

the requirement for a simulated wall against the back side of a

counter-top model.

7. Test Conditions

a. Daily Hot Water Usage. The current test procedure prescribes

water heater testing to determine the energy factor must be based on a

daily hot water usage of 64.3 gallons per day (gpd). DOE did not

propose to change the daily hot water usage in the 1995 proposed

rulemaking.

The American Gas Association (AGA) and Battelle Columbus argued

that the current daily hot water usage is outdated and proposed it be

lowered to 54 gpd to reflect a recent study. (AGA, No. 25 at 2; and

Battelle, No. 46 at 1.) Virginia Power suggested lowering the daily hot

water usage to 50 gpd or less. Virginia Power also stated that because

[[Page 26006]]

the daily usage value is used in energy estimation and design

calculations, changing it to a current value will maximize the

usefulness and applicability of the test results. EEI suggested

lowering the daily hot water usage to 50-57 gpd. Georgia Power argued

for a value close to 50 gpd. (Virginia Power, No. 50 at 3 and February

1997 Transcript at 212 and 223; EEI, February 1997 Transcript at 201;

and Georgia Power, No. 54 at 2.) EPRI stated that there is substantial

evidence, based on its recent study of submetered electric utility load

data from 28 different sources, that the daily hot water consumption

should be less than 50 gallons. However, EPRI, as well as GAMA, the

Oregon State Energy Office, A.O. Smith, and Effikal International

(Effikal), indicated that lowering the gpd value would not alter the

relative efficiency ranking (based on energy factor) of the water

heaters, but would impose an additional cost burden on industry for

retesting and relabeling. The five commenters, therefore, suggested

that DOE maintain the current daily hot water usage of 64.3 gpd in the

test procedure. GAMA also suggested that, if necessary, it is possible

to use linear estimation of energy consumption based on a different

daily usage. The Oregon Energy Office suggested that the variation of

the daily usage value with individual consumers is quite large, and the

current 64.3 gpd may not be too far from the average. (EPRI, No. 56 at

13 and February 1997 Transcript at 221 and at Appendix J at 2; GAMA,

February 1997 Transcript at 215; Oregon State Energy Office, February

1997 Transcript at 219; A.O. Smith, February 1997 Transcript at 220;

Effikal, February 1997 Transcript at 224; and Oregon, No. 51 at 4.)

The Department believes that the current value of 64.3 gpd is

useful in determining an energy factor for consumers to use to compare

water heaters. The Department believes that revising the value so it

can be used to estimate or predict energy consumption will require a

more detailed evaluation of individual installation locations,

thermostat settings, and use patterns. Based on the fact that a revised

daily hot water usage has not been agreed upon, and that the industry

would be financially burdened, the Department concludes that revising

the daily hot water usage is unwarranted in today's Final Rule.

b. Storage Tank Temperature. The existing test procedure uses a

thermostat setting of 135 deg.F 5 deg.F (57.2 deg.C

2.8 deg.C). DOE did not propose to revise this setting in

the 1995 proposed rulemaking. AGA suggested that the thermostat setting

be lowered to 120 deg.F 5 deg.F (48.9 deg.C

2.8 deg.C) to reflect the manufacturers' recommendation to consumers to

lower the temperature settings on water heaters thus preventing

potential scalding. (AGA, No. 25 at 4.)

Both Virginia Power and Bock Water Heaters also supported lowering

the current thermostat setting to 120 deg.F (48.9 deg.C). The reasons

cited included: (1) The current setting of 135 deg.F (57.2 deg.C) does

not reflect how consumers actually operate their water heaters; (2)

most energy-related organizations advocate a setting of 120 deg.

F (48.9 deg.C) when promoting energy efficiency and safety;

(3) scalding by hot water at 135 deg.F (57.2 deg.C) is a major concern

in some areas; and (4) certain local codes restrict the thermostat

setting to be no higher than 120 deg.F (48.9 deg.C). EEI stated that

for several years many customers have been told to set their

thermostats at 120 deg.F (48.9 deg.C). (Virginia Power, No. 50 at 3 and

February 1997 Transcript at 212 and 223; Bock Water Heaters, February

1997 Transcript at 207 and 211; and EEI, February 1997 Transcript at

201.)

In contrast, six commenters, individually or in support of another

commenter's position, opposed lowering the thermostat setting from

135 deg.F 5 deg.F (57.2 deg.C 2.8 deg.C).

(EPRI, No. 56 at 2 and February 1997 Transcript at 199, 208, and 218

and at Appendix J at 1; GAMA, February 1997 Transcript at 215 and at

Appendix I at 3; Oregon State Energy Office, No. 51 at 4 and February

1997 Transcript at 201, 204, and 219; Group Thermo, February 1997

Transcript at 206; A.O. Smith, February 1997 Transcript at 220; and

Effikal International, February 1997 Transcript at 224.) Their various

comments are: (1) A setting at 120 deg.F (48.9 deg.C) could pose a

potential health risk (e.g., legionella) to consumers; (2) a setting at

135 deg.F (57.2 deg.C) is necessary to meet consumers' expected hot

water needs (as with machine-use for washing clothes); (3) a setting at

135 deg.F (57.2 deg.C) reflects realistic household settings; and (4)

changing the thermostat setting from 135 deg.F (57.2 deg.C) will not

alter the comparative ranking of water heaters but would result in a

substantial cost to industry in retesting and relabeling. EEI stated

that it would not object if the current requirement in the test

procedure is not revised. (EEI, February 1997 Transcript at 220.)

Based on the comments in the record regarding actual field

thermostat setting by consumers, potential health concerns and the

potential burden on industry, the Department concludes that revision of

the thermostat setting from 135 deg.F 5 deg.F (57.2 deg.C

2.8 deg.C) to 120 deg.F 5 deg.F (48.9 deg.C

2.8 deg.C) is unwarranted in today's Final Rule.

c. Ambient Air Temperature. The current DOE test procedure

specifies ambient air temperature for heat pump water heaters to be

67\1/2\ deg.F 1 deg.F (19.7 deg.C 0.6 deg.C)

and for all other water heater types to be between 65 deg. F

(18.3 deg.C) and 70 deg. F (21.1 deg.C) . DOE did not propose a change

to these values. EPRI stated that the existing ambient air temperature

values are satisfactory, but suggested using a nationwide survey to

determine more representative ambient air temperature values. (EPRI,

No. 56. at 5.) DOE believes a survey is unnecessary and will continue

to use the current values.

d. Supply Water Temperature. The current DOE test procedure

specifies supply water temperature to be 58 deg.F 2 deg.F

(14.4 deg.C 1.1 deg.C). DOE did not propose a change to

this value. EPRI stated that the existing supply water temperature

value is satisfactory, but suggested revisiting the value periodically

because of the possible change of the average source temperature caused

by regional shifts in the population. (EPRI, No. 56 at 5 and 6.) DOE

believes the current value for supply water temperature is appropriate

and that changing it would place an unreasonable burden on

manufacturers.

e. Relative Humidity. The current DOE test procedure specifies

relative humidity for heat pump water heaters to be between 49% and

51%. DOE did not propose a change to this value. EPRI stated that the

existing humidity value is satisfactory, but suggested using weighted

regional averages in the future to account for humidity extremes.

(EPRI, No. 56 at 5 and 6.) DOE believes the current value for humidity

is appropriate and that changing it would place an unreasonable burden

on manufacturers.

8. Cost-Based Correction Factor for Fossil-Fueled Residential

Appliances

The current procedure provides a test method to measure the energy

efficiency of water heaters that is used to rate units of similar

volumes for comparison purposes. This measure of energy efficiency is

known as the energy factor (EF). DOE did not propose any amendment to

the existing test method in the Proposed Rule.

AGA commented that because the energy factor is calculated from

measurements of the consumption of energy at the site, the EF for

fossil-fueled water heaters is substantially lower than the EF for

electric water heaters. AGA also stated that gas-fired water heaters

typically cost consumers considerably less to operate. AGA stated

[[Page 26007]]

that there is no correlation between the current energy descriptor and

the cost of operation. AGA believes this inconsistency between the

energy descriptor and cost of operation can be extremely misleading to

the consumer if a purchase decision is based primarily on the energy

factor or annual energy consumption. Therefore, AGA suggested that the

energy usage of the water heater be adjusted by a multiplication factor

of 0.298 which represents the ratio of the average cost of fossil fuel

to electricity. (AGA, No. 25 at 5.)

The 0.298 factor is the inverse of DOE's F-factor of 3.36 which was

proposed in the furnaces/boilers, vented home heating equipment and

pool heaters test procedures. The F-factor would have allowed the

consumption of fossil fuel and electricity to be combined into a single

value by placing the two energy types on a common basis. (60 FR 4348,

January 20, 1995.)

In response to disagreement from an overwhelming majority of

commenters regarding the proposed F-factor, the Department stated that

the Energy Policy and Conservation Act, as amended, requires the energy

efficiency of a furnace to be based on consumption of energy at the

site per the definition of ``energy use,'' 42 U.S.C. 6291(4). The

Department also concluded that the statute does not permit the

promulgation of an energy efficiency standard that is expressed in

terms of annual operating costs of the furnace. Based on this analysis,

the Department withdrew the proposed F-Factor in its Final Rule

Regarding Test Procedures for Furnaces/Boilers, Vented Home Heating

Equipment and Pool Heaters. (62 FR 26140, May 12, 1997.) Likewise, DOE

will not adjust the energy factor for electric water heaters to a

source basis as proposed by AGA.

III. Procedural Requirements

A. Review Under the National Environmental Policy Act of 1969

In this rule, the Department will finalize amendments to test

procedures that may be used to implement future energy conservation

standards for water heaters. The Department has determined that this

rule falls into a class of actions that are categorically excluded from

review under the National Environmental Policy Act of 1969 (NEPA), 42

U.S.C. 4321 et seq. The rule is covered by Categorical Exclusion A5,

for rulemakings that interpret or amend an existing rule without

changing the environmental effect, as set forth in the Department's

NEPA regulations at Appendix A to Subpart D, 10 CFR part 1021. This

Final Rule will not affect the quality or distribution of energy usage

and, therefore, will not result in any environmental impacts.

Accordingly, neither an environmental impact statement nor an

environmental assessment is required.

B. Review Under Executive Order 12866, ``Regulatory Planning and

Review'

Today's Final Rule is not a ``significant regulatory action'' under

Executive Order 12866, ``Regulatory Planning and Review.'' 58 FR 51735

(October 4, 1993). Accordingly, today's action is not subject to review

under the Executive Order by the Office of Information and Regulatory

Affairs.

C. Review Under the Regulatory Flexibility Act of 1980

The Regulatory Flexibility Act of 1980, 5 U.S.C. 601-612, requires

that an agency prepare an initial regulatory flexibility analysis for

any rule, for which a general notice of proposed rulemaking is

required, that would have a significant economic effect on small

entities unless the agency certifies that the rule, if promulgated,

will not have a significant economic impact on a substantial number of

small entities. 5 U.S.C. 605. DOE certified in the notice of proposed

rulemaking that the rule would not have a significant economic impact

on a substantial number of small entities. DOE estimates there are

approximately 7 manufacturers of water heaters for specialty markets

that may be small entities as defined in the Regulatory Flexibility

Act. The manufacturers of heat pump water heaters and storage-type

water heaters already make the types of measurements required by this

rule, and the cost of compliance will be negligible. Today's revised

test procedures will have no immediate impact on manufacturers of

instantaneous water heaters because there currently are no energy

efficiency standards for instantaneous water heaters; in any event, the

cost of compliance would not be significant. DOE received no comments

on its certification in the proposed rule.

D. ``Takings'' Assessment Review

DOE has determined pursuant to Executive Order 12630,

``Governmental Actions and Interference with Constitutionally Protected

Property Rights,'' 53 FR 8859 (March 18, 1988), that this regulation,

if adopted, would not result in any takings which might require

compensation under the Fifth Amendment to the United States

Constitution.

E. Federalism Review

Executive Order 12612, ``Federalism,'' 52 FR 41685 (October 30,

1987), requires that regulations, rules, legislation, and any other

policy actions be reviewed for any substantial direct effects on

States, on the relationship between the Federal Government and the

States, or in the distribution of power and responsibilities among

various levels of Government. If there are substantial direct effects,

then this Executive Order requires preparation of a Federalism

assessment to be used in all decisions involved in promulgating and

implementing a policy action.

The Final Rule published today would not regulate the States.

Accordingly, DOE has determined that preparation of a Federalism

assessment is unnecessary.

F. Review Under the Paperwork Reduction Act

No new information or record keeping requirements are imposed by

this rulemaking. Accordingly, no OMB clearance is required under the

Paperwork Reduction Act, 44 U.S.C. 3501 et seq.

G. Review Under Executive Order 12988, ``Civil Justice Reform''

With respect to the review of existing regulations and the

promulgation of new regulations, section 3(a) of Executive Order 12988,

``Civil Justice Reform,'' 61 FR 4729 (February 7, 1996), imposes on

executive agencies the following requirements: (1) Eliminate drafting

errors and ambiguity; (2) write regulations to minimize litigation; and

(3) provide a clear legal standard for affected conduct rather than a

general standard and promote simplification and burden reduction. With

regard to the review required by sections 3(a) and 3(b) of the

Executive Order specifically requires that Executive agencies make

every reasonable effort to ensure that the regulation: (1) Clearly

specifies the preemptive effect, if any; (2) clearly specifies any

effect on existing Federal law or regulation; (3) provides a clear

legal standard for affected conduct while promoting simplification and

reducing burdens; (4) specifies the retroactive effect, if any; (5)

adequately defines key terms; and (6) addresses other important issues

affecting clarity and general draftsmanship under any guidelines issued

by the Attorney General. Section 3(c) of the Executive Order requires

Executive agencies to review regulations in light of applicable

standards in sections 3(a) and 3(b) to determine whether they are met

or it is unreasonable to meet one or more of

[[Page 26008]]

them. DOE reviewed today's rule under the standards of section 3 of the

Executive Order and determined that, to the extent permitted by law, it

meets the requirements of those standards.

H. Review Under the Unfunded Mandates Reform Act of 1995

Title II of the Unfunded Mandates Reform Act of 1995, 2 U.S.C. 1531

et seq., requires each Federal agency, to the extent permitted by law,

to prepare a written assessment of the effects of any Federal mandate

in a final agency rule that may result in the expenditure by State,

local, and tribal governments, in the aggregate, or by the private

sector, of $100 million or more (adjusted annually for inflation) in

one year.

The Department has determined that this Final Rule does not include

any requirements that would result in the expenditure of money by

State, local, and tribal governments. It also would not result in costs

to the private sector of $100 million or more in any one year.

Therefore, the requirements of the Unfunded Mandates Reform Act of 1995

do not apply to this rulemaking.

I. Congressional Notification

Consistent with Subtitle E of the Small Business Regulatory

Enforcement Fairness Act of 1996, 5 U.S.C. 801-808, DOE will submit to

Congress a report regarding the issuance of today's Final Rule prior to

the effective date set forth at the outset of this notice. The report

will note the Office of Management and Budget's determination that this

rule does not constitute a ``major rule'' under that Act. 5 U.S.C. 801,

804.

List of Subjects in 10 CFR Part 430

Administrative practice and procedure, Energy conservation,

Household appliances.

Issued in Washington, D.C., on April 6, 1998.

Dan W. Reicher,

Assistant Secretary, Energy Efficiency and Renewable Energy.

For the reasons set forth in the preamble, Part 430 of Chapter II

of Title 10 of the Code of Federal Regulations is amended as set forth

below:

PART 430--ENERGY CONSERVATION PROGRAM FOR CONSUMER PRODUCTS

1. The authority citation for Part 430 continues to read as

follows:

Authority: Part B, Title III, Energy Policy and Conservation

Act, (42 U.S.C. 6291-6309), as amended.

2. Appendix E to Subpart B of Part 430 is revised to read as

follows:

Appendix E to Subpart B of Part 430--Uniform Test Method for Measuring

the Energy Consumption of Water Heaters

1. Definitions

1.1 Cut-in means the time when or water temperature at which a

water heater control or thermostat acts to increase the energy or

fuel input to the heating elements, compressor, or burner.

1.2 Cut-out means the time when or water temperature at which a

water heater control or thermostat acts to reduce to a minimum the

energy or fuel input to the heating elements, compressor, or burner.

1.3 Design Power Rating means the nominal power rating that a

water heater manufacturer assigns to a particular design of water

heater, expressed in kilowatts or Btu (kJ) per hour as appropriate.

1.4 Energy Factor means a measure of water heater overall

efficiency.

1.5 First-Hour Rating means an estimate of the maximum volume

of ``hot'' water that a storage-type water heater can supply within

an hour that begins with the water heater fully heated (i.e., with

all thermostats satisfied). It is a function of both the storage

volume and the recovery rate.

1.6 Heat Trap means a device which can be integrally connected

or independently attached to the hot and/or cold water pipe

connections of a water heater such that the device will develop a

thermal or mechanical seal to minimize the recirculation of water

due to thermal convection between the water heater tank and its

connecting pipes.

1.7 Instantaneous Water Heaters

1.7.1 Electric Instantaneous Water Heater Reserved.

1.7.2 Gas Instantaneous Water Heater means a water heater that

uses gas as the energy source, initiates heating based on sensing

water flow, is designed to deliver water at a controlled temperature

of less than 180 deg.F (82 deg.C), has an input greater than 50,000

Btu/h (53 MJ/h) but less than 200,000 Btu/h (210 MJ/h), and has a

manufacturer's specified storage capacity of less than 2 gallons

(7.6 liters). The unit may use a fixed or variable burner input.

1.8 Maximum gpm (L/min) Rating means the maximum gallons per

minute (liters per minute) of hot water that can be supplied by an

instantaneous water heater while maintaining a nominal temperature

rise of 77 deg.F (42.8 deg.C) during steady state operation.

1.9 Rated Storage Volume means the water storage capacity of a

water heater, in gallons (liters), as specified by the manufacturer.

1.10 Recovery Efficiency means the ratio of energy delivered to

the water to the energy content of the fuel consumed by the water

heater.

1.11 Standby means the time during which water is not being

withdrawn from the water heater. There are two standby time

intervals used within this test procedure:

stby,1 represents the elapsed time between the

time at which the maximum mean tank temperature is observed after

the sixth draw and subsequent recovery and the end of the 24-hour

test; stby,2 represents the total time during

the 24-hour simulated use test when water is not being withdrawn

from the water heater.

1.12 Storage-type Water Heaters

1.12.1 Electric Storage-type Water Heater means a water heater

that uses electricity as the energy source, is designed to heat and

store water at a thermostatically controlled temperature of less

than 180 deg.F (82 deg.C), has a nominal input of 12 kilowatts

(40,956 Btu/h) or less, and has a rated storage capacity of not less

than 20 gallons (76 liters) nor more than 120 gallons (450 liters).

1.12.2 Gas Storage-type Water Heater means a water heater that

uses gas as the energy source, is designed to heat and store water

at a thermostatically controlled temperature of less than 180 deg.F

(82 deg.C), has a nominal input of 75,000 Btu (79 MJ) per hour or

less, and has a rated storage capacity of not less than 20 gallons

(76 liters) nor more than 100 gallons (380 liters).

1.12.3 Heat Pump Water Heater means a water heater that uses

electricity as the energy source, is designed to heat and store

water at a thermostatically controlled temperature of less than

180 deg.F (82 deg.C), has 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, if the

tank is supplied, has a manufacturer's rated storage capacity of 120

gallons (450 liters) or less. Resistive elements used to provide

supplemental heating may use the same circuit as the compressor if

(1) an interlocking mechanism prevents concurrent compressor

operation and resistive heating or (2) concurrent operation does not

result in the maximum current rating of 24 amperes being exceeded.

Otherwise, the resistive elements and the heat pump components must

use separate circuits. A heat pump water heater may be sold by the

manufacturer with or without a storage tank.

a. Heat Pump Water Heater with Storage Tank means an air-to-

water heat pump sold by the manufacturer with an insulated storage

tank as a packaged unit. The tank and heat pump can be an integral

unit or they can be separated.

b. Heat Pump Water Heater without Storage Tank (also called Add-

on Heat Pump Water Heater) means an air-to-water heat pump designed

for use with a storage-type water heater or a storage tank that is

not specified or supplied by the manufacturer.

1.12.4 Oil Storage-type Water Heater means a water heater that

uses oil as the energy source, is designed to heat and store water

at a thermostatically controlled temperature of less than 180 deg.F

(82 deg.C), has a nominal energy input of 105,000 Btu/h (110 MJ/h)

or less, and has a manufacturer's rated storage capacity of 50

gallons (190 liters) or less.

1.12.5 Storage-type Water Heater of More than 2 Gallons (7.6

Liters) and Less than 20 Gallons (76 Liters). Reserved.

1.13 ASHRAE Standard 41.1-86 means the standard published in

1986 by the American Society of Heating, Refrigerating and Air-

Conditioning Engineers, Inc., and titled Standard Measurement Guide:

Section on Temperature Measurements.

1.14 ASTM-D-2156-80 means the test standard published in 1980

by the American

[[Page 26009]]

Society for Testing and Measurements and titled ``Smoke Density in

Flue Gases from Burning Distillate Fuels, Test Method for''.

1.15 Symbol Usage The following identity relationships are

provided to help clarify the symbology used throughout this

procedure:

Cp specific heat capacity of water

Eannual annual energy consumption of a water heater

Ef energy factor of a water heater

Fhr first-hour rating of a storage-type water heater

Fmax maximum gpm (L/min) rating of an instantaneous water

heater rated at a temperature rise of 77 deg.F (42.8 deg.C) across

the heater

i a subscript to indicate an ith draw during a test

Mi mass of water removed during the ith draw (i=1 to 6)

of the 24-hr simulated use test

M*i for storage-type water heaters, mass of water removed

during the ith draw (i=1 to n) during the first-hour rating test

M10m for instantaneous water heaters, mass of water

removed continuously during a 10-minute interval in the maximum gpm

(L/min) rating test

n for storage-type water heaters, total number of draws during the

first-hour rating test

Q total fossil fuel and/or electric energy consumed during the

entire 24-hr simulated use test

Qd daily water heating energy consumption adjusted for

net change in internal energy

Qda adjusted daily water heating energy consumption with

adjustment for variation of tank to ambient air temperature

difference from nominal value

Qdm overall adjusted daily water heating energy

consumption including Qda and QHWD

Qhr hourly standby losses

QHW daily energy consumption to heat water over the

measured average temperature rise across the water heater

QHWD adjustment to daily energy consumption,

Qhw, due to variation of the temperature rise across the

water heater not equal to the nominal value of 77 deg.F (42.8 deg.C)

Qr energy consumption of fossil fuel or heat pump water

heaters between thermostat (or burner) cut-out prior to the first

draw and cut-out following the first draw of the 24-hr simulated use

test

Qr, max energy consumption of a modulating instantaneous

water heater between cut-out (burner) prior to the first draw and

cut-out following the first draw of the 24-hr simulated use test

Qr, min energy consumption of a modulating instantaneous

water heater from immediately prior to the fourth draw to burner

cut-out following the fourth draw of the 24-hr simulated use test

Qstby total energy consumed by the water heater during

the standby time interval

, 1

Qsu total fossil fueled and/or electric energy consumed

from the beginning of the first draw to the thermostat (or burner)

cut-out following the completion of the sixth draw during the 24-hr

simulated use test

Tmin for modulating instantaneous water heaters, steady

state outlet water temperature at the minimum fuel input rate

T0 mean tank temperature at the beginning of the 24-hr

simulated use test

T24 mean tank temperature at the end of the 24-hr

simulated use test

Ta, stby average ambient air temperature during standby

periods of the 24-hr use test

Tdel for instantaneous water heaters, average outlet

water temperature during a 10-minute continuous draw interval in the

maximum gpm (L/min) rating test

Tdel, i average outlet water temperature during the ith

draw of the 24-hr simulated use test

Tin for instantaneous water heaters, average inlet water

temperature during a 10-minute continuous draw interval in the

maximum gpm (L/min) rating test

Tin, i average inlet water temperature during the ith

draw of the 24-hr simulated use test

Tmax, 1 maximum measured mean tank temperature after cut-

out following the first draw of the 24-hr simulated use test

Tstby average storage tank temperature during the standby

period , 2

of the 24-hr use test

Tsu maximum measured mean tank temperature after cut-out

following the sixth draw of the 24-hr simulated use test

Tt, stby average storage tank temperature during the

standby period

, 1 of the 24-hr use

test

T*del, i for storage-type water heaters, average outlet

water temperature during the ith draw (i=1 to n) of the first-hour

rating test

T*max, i for storage-type water heaters, maximum outlet

water temperature observed during the ith draw (i=1 to n) of the

first-hour rating test

T*min, i for storage-type water heaters, minimum outlet

water temperature to terminate the ith draw during the first-hour

rating test

UA standby loss coefficient of a storage-type water heater

Vi volume of water removed during the ith draw (i=1 to 6)

of the 24-hr simulated use test

V* i volume of water removed during the ith draw (i=1 to

n) during the first-hour rating test

V10m for instantaneous water heaters, volume of water

removed continuously during a 10-minute interval in the maximum gpm

(L/min) rating test

Vmax steady state water flow rate of an instantaneous

water heater at the rated input to give a discharge temperature of

135 deg.F 5 deg.F (57.2 deg.C 2.8 deg.C)

Vmin steady state water flow rate of a modulating

instantaneous water heater at the minimum input to give a discharge

temperature of Tmin up to 135 deg.F 5 deg.F

(57.2 deg.C 2.8 deg.C)

Vst measured storage volume of the storage tank

Wf weight of storage tank when completely filled with

water

Wt tare weight of storage tank when completely empty of

water

nr recovery efficiency

p density of water

, 1 elapsed

time between the time the maximum mean tank temperature is observed

after the sixth draw and the end of the 24-hr simulated use test

, 2 overall

standby periods when no water is withdrawn during the 24-hr

simulated use test

2. Test Conditions

2.1 Installation Requirements. Tests shall be performed with

the water heater and instrumentation installed in accordance with

Section 4 of this appendix.

2.2 Ambient Air Temperature. The ambient air temperature shall

be maintained between 65.0 deg.F and 70.0 deg.F (18.3 deg.C and

21.1 deg.C) on a continuous basis. For heat pump water heaters, the

dry bulb temperature shall be maintained at 67.5 deg.F

1 deg.F (19.7 deg.C 0.6 deg.C) and, in addition, the

relative humidity shall be maintained between 49% and 51%.

2.3 Supply Water Temperature. The temperature of the water

being supplied to the water heater shall be maintained at 58 deg.F

2 deg.F (14.4 deg.C 1.1 deg.C) throughout

the test.

2.4 Storage Tank Temperature. The average temperature of the

water within the storage tank shall be set to 135 deg.F

5 deg.F (57.2 deg.C 2.8 deg.C).

2.5 Supply Water Pressure. During the test when water is not

being withdrawn, the supply pressure shall be maintained between 40

psig (275 kPa) and the maximum allowable pressure specified by the

water heater manufacturer.

2.6 Electrical and/or Fossil Fuel Supply.

2.6.1 Electrical. Maintain the electrical supply voltage to

within 1% of the center of the voltage range specified

by the water heater and/or heat pump manufacturer.

2.6.2 Natural Gas. Maintain the supply pressure in accordance

with the manufacturer's specifications. If the supply pressure is

not specified, maintain a supply pressure of 7-10 inches of water

column (1.7-2.5 kPa). If the water heater is equipped with a gas

appliance pressure regulator, the regulator outlet pressure shall be

within 10% of the manufacturer's specified manifold

pressure. For all tests, use natural gas having a heating value of

approximately 1,025 Btu per standard cubic foot (38,190 kJ per

standard cubic meter).

2.6.3 Propane Gas. Maintain the supply pressure in accordance

with the manufacturer's specifications. If the supply pressure is

not specified, maintain a supply pressure of 11-13 inches of water

column (2.7-3.2 kPa). If the water heater is equipped with a gas

appliance pressure regulator, the regulator outlet pressure shall be

within 10% of the manufacturer's specified manifold

pressure. For all tests, use propane gas with a heating value of

approximately 2,500 Btu per standard cubic foot (93,147 kJ per

standard cubic meter).

2.6.4 Fuel Oil Supply. Maintain an uninterrupted supply of fuel

oil. Use fuel oil

[[Page 26010]]

having a heating value of approximately 138,700 Btu per gallon

(38,660 kJ per liter).

3. Instrumentation

3.1 Pressure Measurements. Pressure-measuring instruments shall

have an error no greater than the following values:

------------------------------------------------------------------------

Item measured Instrument accuracy Instrument precision

------------------------------------------------------------------------

Gas pressure................ 0.1 0.05

inch of water inch of water

column ( 0.025 kPa). minus> 0.012 kPa).

Atmospheric pressure........ 0.1 0.05

inch of mercury inch of mercury

column ( 0.34 kPa). minus> 0.17 kPa).

Water pressure.............. 1.0 0.50

pounds per square pounds per square

inch ( inch (

6.9 kPa). 3.45 kPa).

------------------------------------------------------------------------

3.2 Temperature Measurement

3.2.1 Measurement. Temperature measurements shall be made in

accordance with the Standard Measurement Guide: Section on

Temperature Measurements, ASHRAE Standard 41.1-86.

3.2.2 Accuracy and Precision. The accuracy and precision of the

instruments, including their associated readout devices, shall be

within the following limits:

----------------------------------------------------------------------------------------------------------------

Item measured Instrument accuracy Instrument precision

----------------------------------------------------------------------------------------------------------------

Air dry bulb temperature............. 0.2 deg.F ( 0.1 deg.F ( 0.06

minus> 0.1 deg.C). deg.C)

Air wet bulb temperature............. 0.2 deg.F ( 0.1 deg.F ( 0.06

minus> 0.1 deg.C). deg.C)

Inlet and outlet water temperatures.. 0.2 deg.F ( 0.1 deg.F ( 0.06

minus> 0.1 deg.C). deg.C)

Storage tank temperatures............ 0.5 deg.F ( 0.25 deg.F ( 0.14

minus> 0.3 deg.C). deg.C)

----------------------------------------------------------------------------------------------------------------

3.2.3 Scale Division. In no case shall the smallest scale

division of the instrument or instrument system exceed 2 times the

specified precision.

3.2.4 Temperature Difference. Temperature difference between

the entering and leaving water may be measured with any of the

following:

a. A thermopile

b. Calibrated resistance thermometers

c. Precision thermometers

d. Calibrated thermistors

e. Calibrated thermocouples

f. Quartz thermometers

3.2.5 Thermopile Construction. If a thermopile is used, it

shall be made from calibrated thermocouple wire taken from a single

spool. Extension wires to the recording device shall also be made

from that same spool.

3.2.6 Time Constant. The time constant of the instruments used

to measure the inlet and outlet water temperatures shall be no

greater than 5 seconds.

3.3 Liquid Flow Rate Measurement. The accuracy of the liquid

flow rate measurement, using the calibration if furnished, shall be

equal to or less than 1% of the measured value in mass

units per unit time.

3.4 Electric Energy. The electrical energy used shall be

measured with an instrument and associated readout device that is

accurate within 1% of the reading.

3.5 Fossil Fuels. The quantity of fuel used by the water heater

shall be measured with an instrument and associated readout device

that is accurate within 1% of the reading.

3.6 Mass Measurements. For mass measurements greater than or

equal to 10 pounds (4.5 kg), a scale that is accurate within

1% of the reading shall be used to make the

measurement. For mass measurements less than 10 pounds (4.5 kg), the

scale shall provide a measurement that is accurate within

0.1 pound (0.045 kg).

3.7 Heating Value. The higher heating value of the natural gas,

propane, or fuel oil shall be measured with an instrument and

associated readout device that is accurate within 1% of

the reading. The heating value of natural gas and propane must be

corrected for local temperature and pressure conditions.

3.8 Time. The elapsed time measurements shall be measured with

an instrument that is accurate within 0.5 seconds per

hour.

3.9 Volume. Volume measurements shall be measured with an

accuracy of 2% of the total volume.

4. Installation

4.1 Water Heater Mounting. A water heater designed to be

freestanding shall be placed on a \3/4\ inch (2 cm) thick plywood

platform supported by three 2 x 4 inch (5 cm x 10 cm) runners.

If the water heater is not approved for installation on combustible

flooring, suitable non-combustible material shall be placed between

the water heater and the platform. Counter-top water heaters shall

be placed against a simulated wall section. Wall-mounted water

heaters shall be supported on a simulated wall in accordance with

the manufacturer-published installation instructions. When a

simulated wall is used, the recommended construction is 2 x 4 inch

(5 cm x 10 cm) studs, faced with \3/4\ inch (2 cm) plywood. For

heat pump water heaters that are supplied with a storage tank, the

two components, if not delivered as a single package, shall be

connected in accordance with the manufacturer-published installation

instructions and the overall system shall be placed on the above-

described plywood platform. If installation instructions are not

provided by the heat pump manufacturer, uninsulated 8 foot (2.4 m)

long connecting hoses having an inside diameter of \5/8\ inch (1.6

cm) shall be used to connect the storage tank and the heat pump

water heater. With the exception of using the storage tank described

in 4.10, the same requirements shall apply for heat pump water

heaters that are supplied without a storage tank from the

manufacturer. The testing of the water heater shall occur in an area

that is protected from drafts.

4.2 Water Supply. Connect the water heater to a water supply

capable of delivering water at conditions as specified in Sections

2.3 and 2.5 of this appendix.

4.3 Water Inlet and Outlet Configuration. For freestanding

water heaters that are taller than 36 inches (91.4 cm), inlet and

outlet piping connections shall be configured in a manner consistent

with Figures 1 and 2. Inlet and outlet piping connections for wall-

mounted water heaters shall be consistent with Figure 3. For

freestanding water heaters that are 36 inches or less in height and

not supplied as part of a counter-top enclosure (commonly referred

to as an under-the-counter model), inlet and outlet piping shall be

installed in a manner consistent with Figures 4, 5, and 6. For water

heaters that are supplied with a counter-top enclosure, inlet and

outlet piping shall be made in a manner consistent with Figures 7A

and 7B, respectively. The vertical piping noted in Figures 7A and 7B

shall be located (whether inside the enclosure or along the outside

in a recessed channel) in accordance with the manufacturer-published

installation instructions.

All dimensions noted in Figures 1 through 7 shall be achieved.

All piping between the water heater and the inlet and outlet

temperature sensors, noted as TIN and TOUT in

the figures, shall be Type ``L'' hard copper having the same

diameter as the connections on the water heater. Unions may be used

to facilitate installation and removal of the piping arrangements. A

pressure gauge and diaphragm expansion tank shall be installed in

the supply water piping at a location upstream of the inlet

temperature sensor. An appropriately rated pressure and temperature

relief valve shall be installed on all water heaters at the port

specified by the manufacturer. Discharge piping for the relief valve

shall be non-metallic. If heat traps, piping insulation, or pressure

relief valve insulation are supplied with the water heater, they

shall be installed for testing. Except when using a simulated wall,

clearance shall be provided such that none of the piping contacts

other surfaces in the test room.

4.4 Fuel and/or Electrical Power and Energy Consumption.

Install one or more

[[Page 26011]]

instruments which measure, as appropriate, the quantity and rate of

electrical energy and/or fossil fuel consumption in accordance with

Section 3. For heat pump water heaters that use supplemental

resistive heating, the electrical energy supplied to the resistive

element(s) shall be metered separately from the electrical energy

supplied to the entire appliance or to the remaining components

(e.g., compressor, fans, pumps, controls).

4.5 Internal Storage Tank Temperature Measurements. Install six

temperature measurement sensors inside the water heater tank with a

vertical distance of at least 4 inches (100 mm) between successive

sensors. A temperature sensor shall be positioned at the vertical

midpoint of each of the six equal volume nodes within the tank.

Nodes designate the equal volumes used to evenly partition the total

volume of the tank. As much as is possible, the temperature sensor

should be positioned away from any heating elements, anodic

protective devices, tank walls, and flue pipe walls. If the tank

cannot accommodate six temperature sensors and meet the installation

requirements specified above, install the maximum number of sensors

which comply with the installation requirements. The temperature

sensors shall be installed either through (1) the anodic device

opening; (2) the relief valve opening; or (3) the hot water outlet.

If installed through the relief valve opening or the hot water

outlet, a tee fitting or outlet piping, as applicable, shall be

installed as close as possible to its original location. If the

relief valve temperature sensor is relocated, and it no longer

extends into the top of the tank, a substitute relief valve that has

a sensing element that can reach into the tank shall be installed.

If the hot water outlet includes a heat trap, the heat trap shall be

installed on top of the tee fitting. Added fittings shall be covered

with thermal insulation having an R value between 4 and 8

hft2 deg.F/Btu (0.7 and 1.4

m2 deg.C/W).

4.6 Ambient Air Temperature Measurement. Install an ambient air

temperature sensor at the vertical mid-point of the water heater and

approximately 2 feet (610 mm) from the surface of the water heater.

The sensor shall be shielded against radiation.

4.7 Inlet and Outlet Water Temperature Measurements. Install

temperature sensors in the cold-water inlet pipe and hot-water

outlet pipe as shown in Figures 1, 2, 3, 4, 5, 6, 7a and 7b, as

applicable.

4.8 Flow Control. A valve shall be installed to provide flow as

specified in sections 5.1.4.1 for storage tank water heaters and

5.2.1 for instantaneous water heaters.

4.9 Flue Requirements.

4.9.1 Gas-Fired Water Heaters. Establish a natural draft in the

following manner. For gas-fired water heaters with a vertically

discharging draft hood outlet, a 5-foot (1.5-meter) vertical vent

pipe extension with a diameter equal to the largest flue collar size

of the draft hood shall be connected to the draft hood outlet. For

gas-fired water heaters with a horizontally discharging draft hood

outlet, a 90-degree elbow with a diameter equal to the largest flue

collar size of the draft hood shall be connected to the draft hood

outlet. A 5-foot (1.5-meter) length of vent pipe shall be connected

to the elbow and oriented to discharge vertically upward. Direct

vent gas-fired water heaters shall be installed with venting

equipment specified in the manufacturer's instructions using the

minimum vertical and horizontal lengths of vent pipe recommended by

the manufacturer.

4.9.2 Oil-Fired Water Heaters. Establish a draft at the flue

collar at the value specified in the manufacturer's instructions.

Establish the draft by using a sufficient length of vent pipe

connected to the water heater flue outlet, and directed vertically

upward. For an oil-fired water heater with a horizontally

discharging draft hood outlet, a 90-degree elbow with a diameter

equal to the largest flue collar size of the draft hood shall be

connected to the draft hood outlet. A length of vent pipe sufficient

to establish the draft shall be connected to the elbow fitting and

oriented to discharge vertically upward. Direct-vent oil-fired water

heaters should be installed with venting equipment as specified in

the manufacturer's instructions, using the minimum vertical and

horizontal lengths of vent pipe recommended by the manufacturer.

4.10 Heat Pump Water Heater Storage Tank. The tank to be used

for testing a heat pump water heater without a tank supplied by the

manufacturer (see Section 1.12.3b) shall be an electric storage-type

water heater having a measured volume of 47.0 gallons

1.0 gallon (178 liters 3.8 liters); two 4.5

kW heating elements controlled in such a manner as to prevent both

elements from operating simultaneously; and an energy factor greater

than or equal to the minimum energy conservation standard (as

determined in accordance with Section 6.1.7) and less than or equal

to the sum of the minimum energy conservation standard and 0.02.

5. Test Procedures

5.1 Storage-type Water Heaters, Including Heat Pump Water

Heaters.

5.1.1 Determination of Storage Tank Volume. Determine the

storage capacity, Vst, of the water heater under test, in

gallons (liters), by subtracting the tare weight--measured while the

tank is empty--from the gross weight of the storage tank when

completely filled with water (with all air eliminated and line

pressure applied as described in section 2.5) and dividing the

resulting net weight by the density of water at the measured

temperature.

5.1.2 Setting the Thermostat.

5.1.2.1 Single Thermostat Tanks. Starting with a tank at the

supply water temperature, initiate normal operation of the water

heater. After cut-out, determine the mean tank temperature every

minute until the maximum value is observed. Determine whether this

maximum value for the mean tank temperature is within the range of

135 deg.F5 deg.F (57.2 deg.C2.8 deg.C). If

not, turn off the water heater, adjust the thermostat, drain and

refill the tank with supply water. Then, once again, initiate normal

operation of the water heater, and determine the maximum mean tank

temperature after cut-out. Repeat this sequence until the maximum

mean tank temperature after cut-out is 135 deg.F5 deg.F

(57.2 deg.C2.8 deg.C).

5.1.2.2 Tanks with Two or More Thermostats. Follow the same

sequence as for a single thermostat tank, i.e. start at the supply

water temperature, operate normally until cutout. Determine if the

thermostat that controls the uppermost heating element yields a

maximum water temperature of 135 deg.F5 deg.F

(57.2 deg.C2.8 deg.C), as measured by the in-tank

sensors that are positioned above the uppermost heating element. If

the tank temperature at the thermostat is not within

135 deg.F5 deg.F (57.2 deg.C2.8 deg.C), turn

off the water heater, adjust the thermostat, drain and refill the

tank with supply water. The thermostat that controls the heating

element positioned next highest in the tank shall then be set to

yield a maximum water temperature of 135 deg.F5 deg.F

(57.2 deg.C2.8 deg.C). This process shall be repeated

until the thermostat controlling the lowest element is correctly

adjusted. When adjusting the thermostat that controls the lowest

element, the maximum mean tank temperature after cut-out, as

determined using all the in-tank sensors, shall be

135 deg.F5 deg.F (57.2 deg.C2.8 deg.C). When

adjusting all other thermostats, use only the in-tank temperature

sensors positioned above the heating element in question to evaluate

the maximum water temperature after cut-out.

For heat pump water heaters that control an auxiliary resistive

element, the thermostat shall be set in accordance with the

manufacturer's installation instructions.

5.1.3 Power Input Determination. For all water heaters except

electric types having immersed heating elements, initiate normal

operation and determine the power input, P, to the main burners

(including pilot light power, if any) after 15 minutes of operation.

If the water heater is equipped with a gas appliance pressure

regulator, the regulator outlet pressure shall be set within

10% of that recommended by the manufacturer. For oil-

fired water heaters the fuel pump pressure shall be within

10% of the manufacturer's specified pump pressure. All

burners shall be adjusted to achieve an hourly Btu (kJ) rating that

is within 2% of the value specified by the

manufacturer. For an oil-fired water heater, adjust the burner to

give a CO2 reading recommended by the manufacturer and an

hourly Btu (kJ) rating that is within 2% of that

specified by the manufacturer. Smoke in the flue may not exceed No.

1 smoke as measured by the procedure in ASTM-D-2156-80.

5.1.4 First-Hour Rating Test.

5.1.4.1 General. During hot water draws, remove water at a rate

of 3.00.25 gallons per minute (11.40.95

liters per minute). Collect the water in a container that is large

enough to hold the volume removed during an individual draw and

suitable for weighing at the termination of each draw.

Alternatively, a water meter may be used to directly measure the

water volume(s) withdrawn.

5.1.4.2 Draw Initiation Criteria. Begin the first-hour rating

test by imposing a draw on the storage-type water heater. After

completion of this first draw, initiate successive draws based on

the following criteria. For gas-and oil-fired water heaters,

initiate successive draws when the thermostat acts to reduce the

supply of fuel to the main burner. For electric water heaters having

a single element or multiple elements that all operate

simultaneously, initiate

[[Page 26012]]

successive draws when the thermostat acts to reduce the electrical

input supplied to the element(s). For electric water heaters having

two or more elements that do not operate simultaneously, initiate

successive draws when the applicable thermostat acts to reduce the

electrical input to the element located vertically highest in the

storage tank. For heat pump waters heaters that do not use

supplemental resistive heating, initiate successive draws

immediately after the electrical input to the compressor is reduced

by the action of the water heater's thermostat. For heat pump waters

heaters that use supplemental resistive heating, initiate successive

draws immediately after the electrical input to the compressor or

the uppermost resistive element is reduced by the action of the

applicable water heater thermostat. This draw initiation criterion

for heat pump water heaters that use supplemental resistive heating,

however, shall only apply when the water located above the

thermostat at cut-out is heated to 135 deg.F5 deg.F

(57.2 deg.C2.8 deg.C).

5.1.4.3 Test Sequence. Establish normal water heater operation.

If the water heater is not presently operating, initiate a draw. The

draw may be terminated anytime after cut-in occurs. After cut-out

occurs (i.e., all thermostats are satisfied), monitor the internal

storage tank temperature sensors described in section 4.5 every

minute.

Initiate a draw after a maximum mean tank temperature has been

observed following cut-out. Record the time when the draw is initiated

and designate it as an elapsed time of zero (* = 0). (The

superscript * is used to denote variables pertaining to the first-hour

rating test.) Record the outlet water temperature beginning 15 seconds

after the draw is initiated and at 5-second intervals thereafter until

the draw is terminated. Determine the maximum outlet temperature that

occurs during this first draw and record it as T*max, 1. For

the duration of this first draw and all successive draws, in addition,

monitor the inlet temperature to the water heater to ensure that the

required 58 deg.F2 deg.F (14.4 deg.C1.1 deg.C)

test condition is met. Terminate the hot water draw when the outlet

temperature decreases to T*max,1-25 deg.F

(T*max,1-13.9 deg.C). Record this temperature as

T*min,1. Following draw termination, determine the average

outlet water temperature and the mass or volume removed during this

first draw and record them as T*del,1 and M*1 or

V*1, respectively.

Initiate a second and, if applicable, successive draw each time the

applicable draw initiation criteria described in section 5.1.4.2 are

satisfied. As required for the first draw, record the outlet water

temperature 15 seconds after initiating each draw and at 5-second

intervals thereafter until the draw is terminated. Determine the

maximum outlet temperature that occurs during each draw and record it

as T*max, i, where the subscript i refers to the draw

number. Terminate each hot water draw when the outlet temperature

decreases to T*max, i-25 deg.F

(T*max, i-13.9 deg.C). Record this temperature as

T*min, i. Calculate and record the average outlet

temperature and the mass or volume removed during each draw

(T*del, i and M*i or V*i,

respectively). Continue this sequence of draw and recovery until one

hour has elapsed, then shut off the electrical power and/or fuel

supplied to the water heater.

If a draw is occurring at an elapsed time of one hour, continue

this draw until the outlet temperature decreases to

T*max, n-25 deg.F (T*max, n -13.9 deg.C), at

which time the draw shall be immediately terminated. (The subscript n

shall be used to denote quantities associated with the final draw.) If

a draw is not occurring at an elapsed time of one hour, a final draw

shall be imposed at one hour. This draw shall be immediately terminated

when the outlet temperature first indicates a value less than or equal

to the cut-off temperature used for the previous draw

(T*min, n-1). For cases where the outlet temperature is

close to T*min, n-1, the final draw shall proceed for a

minimum of 30 seconds. If an outlet temperature greater than

T*min, n-1 is not measured within 30 seconds, the draw shall

be immediately terminated and zero additional credit shall be given

towards first-hour rating (i.e., M*n = 0 or V*n =

0). After the final draw is terminated, calculate and record the

average outlet temperature and the mass or volume removed during the

draw (T*del, n and M*n or V*n,

respectively).

5.1.5 24-Hour Simulated Use Test. During the simulated use

test, a total of 64.3 1.0 gallons (2433.8

liters) shall be removed. This value is referred to as the daily hot

water usage in the following text.

With the water heater turned off, fill the water heater with

supply water and apply pressure as described in section 2.5. Turn on

the water heater and associated heat pump unit, if present. After

the cut-out occurs, the water heater may be operated for up to three

cycles of drawing until cut-in, and then operating until cut-out,

prior to the start of the test.

At this time, record the mean tank temperature (To),

and the electrical and/or fuel measurement readings, as appropriate.

Begin the 24-hour simulated use test by withdrawing a volume from

the water heater that equals one-sixth of the daily hot water usage.

Record the time when this first draw is initiated and assign it as

the test elapsed time () of zero (0). Record the average

storage tank and ambient temperature every 15 minutes throughout the

24-hour simulated use test unless a recovery or a draw is occurring.

At elapsed time intervals of one, two, three, four, and five hours

from = 0, initiate additional draws, removing an amount of

water equivalent to one-sixth of the daily hot water usage with the

maximum allowable deviation for any single draw being

0.5 gallons (1.9 liters). The quantity of water withdrawn during the

sixth draw shall be increased or decreased as necessary such that

the total volume of water withdrawn equals 64.3 gallons

1.0 gallon (243.4 liters 3.8 liters).

All draws during the simulated use test shall be made at flow

rates of 3.0 gallons 0.25 gallons per minute (11.4

liters 0.95 liters per minute). Measurements of the

inlet and outlet temperatures shall be made 15 seconds after the

draw is initiated and at every subsequent 5-second interval

throughout the duration of each draw. The arithmetic mean of the hot

water discharge temperature and the cold water inlet temperature

shall be determined for each draw (Tdel, i and

Tin, i). Determine and record the net mass or volume

removed (Mi or Vi ), as appropriate, after

each draw.

At the end of the recovery period following the first draw,

record the maximum mean tank temperature observed after cut-out,

Tmax, 1, and the energy consumed by an electric

resistance, gas or oil-fired water heater, Qr. For heat

pump water heaters, the total electrical energy consumed during the

first recovery by the heat pump (including compressor, fan,

controls, pump, etc.) and, if applicable, by the resistive

element(s) shall be recorded as Qr.

At the end of the recovery period that follows the sixth draw,

determine and record the total electrical energy and/or fossil fuel

consumed since the beginning of the test, Qsu. In

preparation for determining the energy consumed during standby,

record the reading given on the electrical energy (watt-hour) meter,

the gas meter, and/or the scale used to determine oil consumption,

as appropriate. Record the maximum value of the mean tank

temperature after cut-out as Tsu. Except as noted below,

allow the water heater to remain in the standby mode until 24 hours

have elapsed from the start of the test (i.e., since = 0). Prevent

the water heater from beginning a recovery cycle during the last

hour of the test by turning off the electric power to the electrical

heating elements and heat pump, if present, or by turning down the

fuel supply to the main burner at an elapsed time of 23 hours. If a

recovery is taking place at an elapsed time of 23 hours, wait until

the recovery is complete before reducing the electrical and/or fuel

supply to the water heater. At 24 hours, record the mean tank

temperature, T24, and the electric and/or fuel instrument

readings. Determine the total fossil fuel or electrical energy

consumption, as appropriate, for the entire 24-hour simulated use

test, Q. Record the time interval between the time at which the

maximum mean tank temperature is observed after the sixth draw and

the end of the 24-hour test as stby, 1. Record the time

during which water is not being withdrawn from the water heater

during the entire 24-hour period as stby, 2.

5.2 Instantaneous Gas and Electric Water Heaters

5.2.1 Setting the Outlet Discharge Temperature. Initiate normal

operation of the water heater at the full input rating for electric

instantaneous water heaters and at

[[Page 26013]]

the maximum firing rate specified by the manufacturer for gas

instantaneous water heaters. Monitor the discharge water temperature

and set to a value of 135 deg.F 5 deg.F (57.2 deg.C

2.8 deg.C) in accordance with the manufacturer's

instructions. If the water heater is not capable of providing this

discharge temperature when the flow rate is 3.0 gallons

0.25 gallons per minute (11.4 liters 0.95 liters per

minute), then adjust the flow rate as necessary to achieve the

specified discharge water temperature. Record the corresponding flow

rate as Vmax.

5.2.2 Additional Requirements for Variable Input Instantaneous

Gas Water Heaters. If the instantaneous water heater incorporates a

controller that permits operation at a reduced input rate, adjust

the flow rate as necessary to achieve a discharge water temperature

of 135 deg.F 5 deg.F (57.2 deg.C

2.8 deg.C) while maintaining the minimum input rate. Record the

corresponding flow rate as Vmin. If an outlet temperature

of 135 deg.F 5 deg.F (57.2 deg.C

2.8 deg.C) cannot be achieved at the minimum flow rate permitted by

the instantaneous water heater, record the flow rate as

Vmin and the corresponding outlet temperature as

Tmin.

5.2.3 Maximum GPM Rating Test for Instantaneous Water Heaters.

Establish normal water heater operation at the full input rate for

electric instantaneous water heaters and at the maximum firing rate

for gas instantaneous water heaters with the discharge water

temperature set in accordance with Section 5.2.1. During the 10-

minute test, either collect the withdrawn water for later

measurement of the total mass removed, or alternatively, use a water

meter to directly measure the water volume removed.

After recording the scale or water meter reading, initiate water

flow throughout the water heater, record the inlet and outlet water

temperatures beginning 15 seconds after the start of the test and at

subsequent 5-second intervals throughout the duration of the test.

At the end of 10 minutes, turn off the water. Determine the mass of

water collected, M10m, in pounds (kilograms), or the

volume of water, V10m, in gallons (liters).

5.2.4 24-hour Simulated Use Test for Gas Instantaneous Water

Heaters.

5.2.4.1 Fixed Input Instantaneous Water Heaters. Establish

normal operation with the discharge water temperature and flow rate

set to values of 135 deg.F 5 deg.F (57.2 deg.C

2.8 deg.C) and Vmax per Section 5.2.1,

respectively. With no draw occurring, record the reading given by

the gas meter and/or the electrical energy meter as appropriate.

Begin the 24-hour simulated use test by drawing an amount of water

out of the water heater equivalent to one-sixth of the daily hot

water usage. Record the time when this first draw is initiated and

designate it as an elapsed time, , of 0. At elapsed time

intervals of one, two, three, four, and five hours from =

0, initiate additional draws, removing an amount of water equivalent

to one-sixth of the daily hot water usage, with the maximum

allowable deviation for any single draw being 0.5

gallons (1.9 liters). The quantity of water drawn during the sixth

draw shall be increased or decreased as necessary such that the

total volume of water withdrawn equals 64.3 gallons 1.0

gallons (243.4 liters 3.8 liters).

Measurements of the inlet and outlet water temperatures shall be

made 15 seconds after the draw is initiated and at every 5-second

interval thereafter throughout the duration of the draw. The

arithmetic mean of the hot water discharge temperature and the cold

water inlet temperature shall be determined for each draw. Record

the scale used to measure the mass of the withdrawn water or the

water meter reading, as appropriate, after each draw. At the end of

the recovery period following the first draw, determine and record

the fossil fuel or electrical energy consumed, Qr.

Following the sixth draw and subsequent recovery, allow the water

heater to remain in the standby mode until exactly 24 hours have

elapsed since the start of the test (i.e., since = 0). At

24 hours, record the reading given by the gas meter and/or the

electrical energy meter as appropriate. Determine the fossil fuel or

electrical energy consumed during the entire 24-hour simulated use

test and designate the quantity as Q.

5.2.4.2 Variable Input Instantaneous Water Heaters. If the

instantaneous water heater incorporates a controller that permits

continuous operation at a reduced input rate, the first three draws

shall be conducted using the maximum flow rate, Vmax,

while removing an amount of water equivalent to one-sixth of the

daily hot water usage, with the maximum allowable deviation for any

one of the three draws being 0.5 gallons (1.9 liters).

The second three draws shall be conducted at Vmin. If an

outlet temperature of 135 deg.F 5 deg.F (57.2 deg.C

2.8 deg.C) could not be achieved at the minimum flow

rate permitted by the instantaneous water heater, the last three

draws should be lengthened such that the volume removed is:

[GRAPHIC] [TIFF OMITTED] TR11MY98.001

or

[GRAPHIC] [TIFF OMITTED] TR11MY98.002

where Tmin is the outlet water temperature at the flow

rate Vmin as determined in Section 5.2.1, and where the

maximum allowable variation for any one of the three draws is

0.5 gallons (1.9 liters). The quantity of water

withdrawn during the sixth draw shall be increased or decreased as

necessary such that the total volume of water withdrawn equals

(32.15 + 31V4,5,6) 1.0

gallons

((121.7 + 3V. 4,5,6) 3.8

liters).

Measurements of the inlet and outlet water temperatures shall be

made 5 seconds after a draw is initiated and at every 5-second

interval thereafter throughout the duration of the draw. Determine

the arithmetic mean of the hot water discharge temperature and the

cold water inlet temperature for each draw. Record the scale used to

measure the mass of the withdrawn water or the water meter reading,

as appropriate, after each draw. At the end of the recovery period

following the first draw, determine and record the fossil fuel or

electrical energy consumed, Qr, max. Likewise, record the

reading of the meter used to measure fossil fuel or electrical

energy consumption prior to the fourth draw and at the end of the

recovery period following the fourth draw, and designate the

difference as Qr,min. Following the sixth draw and

subsequent recovery, allow the water heater to remain in the standby

mode until exactly 24 hours have elapsed since the start of the test

(i.e., since =0). At 24 hours, record the reading given by

the gas meter and/or the electrical energy meter, as appropriate.

Determine the fossil fuel or electrical energy consumed during the

entire 24-hour simulated use test and designate the quantity as Q.

6. Computations

6.1 Storage Tank and Heat Pump Water Heaters.

6.1.1 Storage Tank Capacity. The storage tank capacity is

computed using the following:

[GRAPHIC] [TIFF OMITTED] TR11MY98.003

Where:

Vst = the storage capacity of the water heater, gal (L).

Wf = the weight of the storage tank when completely

filled with water, lb (kg).

Wt = the (tare) weight of the storage tank when

completely empty, lb (kg).

= the density of water used to fill the tank measured at

the temperature of the water, lb/gal (kg/L).

6.1.2. First-Hour Rating Computation. For the case in which the

final draw is initiated at or prior to an elapsed time of one hour,

the first-hour rating shall be computed using,

[GRAPHIC] [TIFF OMITTED] TR11MY98.004

Where:

n = the number of draws that are completed during the first-hour

rating test.

V*i = the volume of water removed during the ith draw of

the first-hour rating test, gal (L)

or, if the mass of water is being measured,

[GRAPHIC] [TIFF OMITTED] TR11MY98.005

Where:

M*i = the mass of water removed during the ith draw of

the first-hour rating test, lb (kg).

= the water density corresponding to the average outlet

temperature measured during the ith draw, (T*del, I), lb/

gal (kg/L).

For the case in which a draw is not in progress at the elapsed

time of one hour and a final draw is imposed at the elapsed time of

one hour, the first-hour rating shall be calculated using

[[Page 26014]]

[GRAPHIC] [TIFF OMITTED] TR11MY98.006

where n and V*i are the same quantities as defined above,

and

V*n = the volume of water drawn during the nth (final)

draw of the first-hour rating test, gal (L)

T*del,n-1 = the average water outlet temperature measured

during the (n-1)th draw of the first-hour rating test, deg.F

( deg.C).

T*del,n = the average water outlet temperature measured

during the nth (final) draw of the first-hour rating test, deg.F

( deg.C).

T*min,n-1 = the minimum water outlet temperature measured

during the (n-1)th draw of the first-hour rating test, deg.F

( deg.C).

6.1.3 Recovery Efficiency. The recovery efficiency for gas,

oil, and heat pump storage-type water heaters is computed as:

[GRAPHIC] [TIFF OMITTED] TR11MY98.007

Where:

M1 = total mass removed during the first draw of the 24-

hour simulated use test, lb (kg), or, if the volume of water is

being measured,

M1 = V1 1

Where:

V1 = total volume removed during the first draw of the

24-hour simulated use test, gal (L).

1 = density of the water at the water

temperature measured at the point where the flow volume is measured,

lb/gal (kg/L).

Cp1 = specific heat of the withdrawn water,

(Tdel,1 + Tin,1) / 2, Btu/lb deg.F (kJ/

kg deg.C).

Tdel,1 = average water outlet temperature measured during

the first draw of the 24-hour simulated use test, deg.F ( deg.C).

Tin,1 = average water inlet temperature measured during

the first draw of the 24-hour simulated use test, deg.F ( deg.C).

Vst = as defined in section 6.1.1.

2 = density of stored hot water,

(Tmax,1 + To)/2, lb/gal (kg/L).

Cp2 = specific heat of stored hot water evaluated at

(Tmax,1 + To) / 2, Btu/lb deg.F (kJ/

kg+ deg.C).

Tmax,1 = maximum mean tank temperature recorded after

cut-out following the first draw of the 24-hour simulated use test,

deg.F ( deg.C).

To = maximum mean tank temperature recorded prior to the

first draw of the 24-hour simulated use test, deg.F ( deg.C).

Qr = the total energy used by the water heater between

cut-out prior to the first draw and cut-out following the first

draw, including auxiliary energy such as pilot lights, pumps, fans,

etc., Btu (kJ). (Electrical auxiliary energy shall be converted to

thermal energy using the following conversion: 1 kWh = 3,412 Btu.)

The recovery efficiency for electric water heaters with immersed

heating elements is assumed to be 98%.

6.1.4 Hourly Standby Losses. The hourly standby energy losses

are computed as:

[GRAPHIC] [TIFF OMITTED] TR11MY98.008

Where:

Qhr = the hourly standby energy losses of the water

heater, Btu/h (kJ/h).

Qstby = the total energy consumed by the water heater

between the time at which the maximum mean tank temperature is

observed after the sixth draw and the end of the 24-hour test

period, Btu (kJ).

Vst = as defined in section 6.1.1.

= density of stored hot water, (T24 +

Tsu) / 2, lb/gal (kg/L).

Cp = specific heat of the stored water, (T24 +

Tsu) / 2, Btu/lb deg.F (kJ/kg deg.C).

T24 = the mean tank temperature at the end of the 24-hour

simulated use test, deg.F ( deg.C).

Tsu = the maximum mean tank temperature observed after

the sixth draw, deg.F ( deg.C).

r = as defined in section 6.1.3.

stby, 1 = elapsed time between the time at which

the maximum mean tank temperature is observed after the sixth draw

and the end of the 24-hour simulated use test, h.

The standby heat loss coefficient for the tank is computed as:

[GRAPHIC] [TIFF OMITTED] TR11MY98.009

Where:

UA = standby heat loss coefficient of the storage tank, Btu/

h deg.F (kJ/h deg.C).

Qhr = as defined in this section.

Tt, stby,1= overall average storage tank temperature

between the time when the maximum mean tank temperature is observed

after the sixth draw and the end of the 24-hour simulated use test,

deg.F ( deg.C).

Ta, stby,1= overall average ambient temperature between

the time when the maximum mean tank temperature is observed after

the sixth draw and the end of the 24-hour simulated use test, deg.F

( deg.C).

6.1.5 Daily Water Heating Energy Consumption. The daily water

heating energy consumption, Qd, is computed as:

[GRAPHIC] [TIFF OMITTED] TR11MY98.010

Where:

Q = total energy used by the water heater during the 24-hour

simulated use test including auxiliary energy such as pilot lights,

pumps, fans, etc., Btu (kJ). (Electrical auxiliary energy shall be

converted to thermal energy using the following conversion: 1 kWh =

3,412 Btu.)

Vst = as defined in section 6.1.1.

= density of the stored hot water, (T24 +

To) / 2, lb/gal (kg/L).

Cp = specific heat of the stored water, (T24 +

To) / 2, Btu/lb deg.F (kJ/kg deg.C).

T24 = mean tank temperature at the end of the 24-hour

simulated use test, deg.F ( deg.C).

To = mean tank temperature at the beginning of the 24-

hour simulated use test, recorded one minute before the first draw

is initiated, deg.F ( deg.C).

r = as defined in section 6.1.3.

6.1.6 Adjusted Daily Water Heating Energy Consumption. The

adjusted daily water heating energy consumption, Qda,

takes into account that the temperature difference between the

storage tank and surrounding ambient air may not be the nominal

value of 67.5 deg.F (135 deg.F-67.5 deg.F) or 37.5 deg.C

(57.2 deg.C-19.7 deg.C) due to the 10 deg.F (5.6 deg.C) allowable

variation in storage tank temperature, 135 deg.F

5 deg.F (57.2 deg.C 2.8 deg.C), and the 5 deg.F

(2.8 deg.C) allowable variation in surrounding ambient temperature

65 deg.F (18.3 deg.C) to 70 deg.F (21.1 deg.C). The adjusted daily

water heating energy consumption is computed as:

Qda = QD - [(Tstby, 2 -

Ta, stby,2) - (135 deg.F - 67.5 deg.F)]

UAstby, 2

or Qda = QD - [(Tstby, 2

- Ta, stby, 2) - (57.2 deg.C - 19.7 deg.C)]

UAstby, 2

Where:

Qda = the adjusted daily water heating energy

consumption, Btu (kJ).

Qd = as defined in section 6.1.5.

Tstby, 2 = the mean tank temperature during the total

standby portion, stby, 2, of the 24-hour test,

deg.F ( deg.C).

Ta, stby, 2 = the average ambient temperature during the

total standby portion, stby, 2, of the 24-

hour test, deg.F ( deg.C).

UA = as defined in section 6.1.4.

stby, 2 = the number of hours during the 24-hour

simulated test when water is not being withdrawn from the water

heater.

A modification is also needed to take into account that the

temperature difference between the outlet water temperature and

supply water temperature may not be equivalent to the nominal value

of 77 deg.F

[[Page 26015]]

(135 deg.F-58 deg.F) or 42.8 deg.C (57.2 deg.C-14.4 deg.C). The

following equations adjust the experimental data to a nominal

77 deg.F (42.8 deg.C) temperature rise.

The energy used to heat water, Btu/day (kJ/day), may be computed

as:

[GRAPHIC] [TIFF OMITTED] TR11MY98.011

Where:

Mi = the mass withdrawn for the ith draw (i = 1 to 6), lb

(kg).

Cpi = the specific heat of the water of the ith draw,

Btu/lb deg.F (kJ/kg deg.C).

Tdel, i = the average water outlet temperature measured

during the ith draw (i=1 to 6), deg.F ( deg.C).

Tin, i = the average water inlet temperature measured

during the ith draw (i=1 to 6), deg.F ( deg.C).

r = as defined in section 6.1.3.

The energy required to heat the same quantity of water over a

77 deg.F (42.8 deg.C) temperature rise, Btu/day (kJ/day), is:

[GRAPHIC] [TIFF OMITTED] TR11MY98.012

The difference between these two values is:

QHWD = QHW, 77+-F -QHW

or QHWD = QHW,42.8+-F -QHW

which must be added to the adjusted daily water heating energy

consumption value. Thus, the daily energy consumption value which

takes into account that the temperature difference between the

storage tank and ambient temperature may not be 67.5 deg.F

(37.5 deg.C) and that the temperature rise across the storage tank

may not be 77 deg.F (42.8 deg.C) is:

Qdm = Qda + QHWD

6.1.7 Energy Factor. The energy factor, Ef, is computed as:

[GRAPHIC] [TIFF OMITTED] TR11MY98.013

or

[GRAPHIC] [TIFF OMITTED] TR11MY98.014

Where:

Qdm = the modified daily water heating energy consumption

as computed in accordance with section 6.1.6, Btu (kJ).

Mi = the mass withdrawn for the ith draw (i = 1 to 6), lb

(kg).

Cpi = the specific heat of the water of the ith draw,

Btu/lb deg.F (kJ/kg deg.C).

6.1.8 Annual Energy Consumption. The annual energy consumption

for storage-type and heat pump water heaters is computed as:

Eannual = 365 x Qdm

Where:

Qdm = the modified daily water heating energy consumption

as computed in accordance with section 6.1.6, Btu (kJ).

365 = the number of days in a year.

6.2 Instantaneous Water Heaters.

6.2.1 Maximum GPM (L/min) Rating Computation. Compute the

maximum gpm (L/min) rating as:

[GRAPHIC] [TIFF OMITTED] TR11MY98.015

which may be expressed as:

[GRAPHIC] [TIFF OMITTED] TR11MY98.016

Where:

M10m = the mass of water collected during the 10-minute

test, lb (kg).

Tdel = the average delivery temperature, deg.F ( deg.C).

Tin = the average inlet temperature, deg.F ( deg.C).

= the density of water at the average delivery

temperature, lb/gal (kg/L).

If a water meter is used the maximum gpm (L/min) rating is

computed as:

[GRAPHIC] [TIFF OMITTED] TR11MY98.017

Where:

V10m = the volume of water measured during the 10-minute

test, gal (L).

Tdel = as defined in this section.

Tin = as defined in this section.

6.2.2 Recovery Efficiency

6.2.2.1 Fixed Input Instantaneous Water Heaters. The recovery

efficiency is computed as:

[GRAPHIC] [TIFF OMITTED] TR11MY98.018

Where:

M1 = total mass removed during the first draw of the 24-

hour simulated use test, lb (kg), or, if the volume of water is

being measured,

M1 = V1 .

Where:

V1 = total volume removed during the first draw of the

24-hour simulated use test, gal (L).

= density of the water at the water temperature measured at

the point where the flow volume is measured, lb/gal (kg/L).

Cp1 = specific heat of the withdrawn water,

(Tdel,1 + Tin,1) / 2, Btu/lb deg.F (kJ/kg

deg.C).

Tdel, 1 = average water outlet temperature measured

during the first draw of the 24-hour simulated use test, deg.F

( deg.C).

Tin, 1 = average water inlet temperature measured during

the first draw of the 24-hour simulated use test, deg.F ( deg.C).

Qr = the total energy used by the water heater between

cut-out prior to the first draw and cut-out following the first

draw, including auxiliary energy such as pilot lights, pumps, fans,

etc., Btu (kJ). (Electrical auxiliary energy shall be converted to

thermal energy using the following conversion: 1 kWh = 3,412 Btu.)

6.2.2.2 Variable Input Instantaneous Water Heaters. For

instantaneous water heaters that have a variable firing rate, two

recovery efficiency values are computed, one at the maximum input

rate and one at the minimum input rate. The recovery efficiency used

in subsequent computations is taken as the average of these two

values. The maximum recovery efficiency is computed as:

[GRAPHIC] [TIFF OMITTED] TR11MY98.019

Where:

M1 = as defined in section 6.2.2.1.

Cp1 = as defined in section 6.2.2.1.

Tdel, 1 = as defined in section 6.2.2.1.

Tin, 1 = as defined in section 6.2.2.1.

Qr, max = the total energy used by the water heater

between burner cut-out prior to the first draw and burner cut-out

following the first draw, including auxiliary energy such as pilot

lights, Btu (kJ).

The minimum recovery efficiency is computed as:

[GRAPHIC] [TIFF OMITTED] TR11MY98.020

Where:

M4 = the mass withdrawn during the fourth draw, lb (kg),

or, if the volume of water is being measured,

M4 = V4

Where:

V4 = total volume removed during the first draw of the

24-hour simulated use test, gal (L).

= as defined in 6.2.2.1

Cp4 = the specific heat of water, Btu/lb deg.F (kJ/kg

deg.C).

Tdel, 4 = the average delivery temperature for the fourth

draw, deg.F ( deg.C).

Tin, 4 = the average inlet temperature for the fourth

draw, deg.F ( deg.C).

Qr, min = the total energy consumed between the beginning

of the fourth draw and burner cut-out following the fourth draw,

including auxiliary energy such as pilot lights, Btu (kJ).

The recovery efficiency is computed as:

[[Page 26016]]

[GRAPHIC] [TIFF OMITTED] TR11MY98.021

Where:

r,max = as calculated above.

r,min = as calculated above.

6.2.3 Daily Water Heating Energy Consumption. The daily water

heating energy consumption, Qd, is computed as:

Qd = Q

Where:

Q = the energy used by the instantaneous water heater during the 24-

hr simulated use test.

A modification is needed to take into account that the

temperature difference between the outlet water temperature and

supply water temperature may not be equivalent to the nominal value

of 77 deg.F (135 deg.F-58 deg.F) or 42.8 deg.C

(57.2 deg.C-14.4 deg.C). The following equations adjust the

experimental data to a nominal 77 deg.F (42.8 deg.C) temperature

rise.

The energy used to heat water may be computed as:

[GRAPHIC] [TIFF OMITTED] TR11MY98.022

Where:

Mi = the mass withdrawn during the ith draw, lb (kg).

Cpi = the specific heat of water of the ith draw, Btu/

lb deg.F (kJ/kg ( deg.C).

Tdel,i = the average delivery temperature of the ith

draw, deg.F ( deg.C).

Tin,i = the average inlet temperature of the ith draw,

deg.F ( deg.C).

r = as calculated in section 6.2.2.2.

The energy required to heat the same quantity of water over a

77 deg.F (42.8 deg.C) temperature rise is:

[GRAPHIC] [TIFF OMITTED] TR11MY98.023

Where:

Mi = the mass withdrawn during the ith draw, lb (kg).

Cpi = the specific heat of water of the ith draw, Btu/

lb deg.F (kJ/kg ( deg.C).

r = as calculated above.

The difference between these two values is:

QHWD = QHW, 77 deg.F - QHW

or QHWD = QHW, 42.8 deg.C -

QHW

which much be added to the daily water heating energy

consumption value. Thus, the daily energy consumption value which

takes into account that the temperature rise across the storage tank

may not be 77 deg.F (42.8 deg.C) is:

Qdm = Qd + QHWD

6.2.4 Energy Factor. The energy factor, Ef, is

computed as:

[GRAPHIC] [TIFF OMITTED] TR11MY98.024

Where:

Qdm = the daily water heating energy consumption as

computed in accordance with section 6.2.3, Btu (kJ).

Mi = the mass associated with the ith draw, lb (kg).

Cpi = the specific heat of water computed at a

temperature of (58 deg.F + 135 deg.F) / 2, Btu/lb deg.F

[(14.4 deg.C + 57.2 deg.C) / 2, kJ/kg deg.C].

6.2.5 Annual Energy Consumption. The annual energy consumption

for instantaneous type water heaters is computed as:

Eannual = 365 x Qdm

Where:

Qdm = the modified daily energy consumption, Btu/day (kJ/

day).

365 = the number of days in a year.

7. Ratings for Untested Models

In order to relieve the test burden on manufacturers who offer

water heaters which differ only in fuel type or power input, ratings

for untested models may be established in accordance with the

following procedures. In lieu of the following procedures a

manufacturer may elect to test the unit for which a rating is

sought.

7.1 Gas Water Heaters. Ratings obtained for gas water heaters

using natural gas can be used for an identical water heater which

utilizes propane gas if the input ratings are within

10%.

7.2 Electric Water Heaters

7.2.1 First-Hour Rating. If an electric storage-type water

heater is available with more than one input rating, the

manufacturer shall designate the standard input rating, and the

water heater need only be tested with heating elements at the

designated standard input ratings. The first-hour ratings for units

having power input rating less than the designated standard input

rating shall be assigned a first-hour rating equivalent to the first

draw of the first-hour rating for the electric water heater with the

standard input rating. For units having power inputs greater than

the designated standard input rating, the first-hour rating shall be

equivalent to that measured for the water heater with the standard

input rating.

7.2.2 Energy Factor. The energy factor for identical electric

storage-type water heaters, with the exception of heating element

wattage, may use the energy factor obtained during testing of the

water heater with the designated standard input rating.

[FR Doc. 98-12296 Filed 5-8-98; 8:45 am]

BILLING CODE 6450-01-P