., ' * ^ -;~~~~~;4 I eAppendix B Supplement

Technology Assessment and Screening Analysis

j::::- .. Aft . . ...X : ' ,f,~~~~~~:i~:'- ::SST7 .'::j~ii::i 

. ........-. 7 F :i f ....-........... ........... ~ ~ ~ ~~~~~~~~~li:il~lli~:-li:::::.

.......... ~~~~~~~~~~~~~~::--

is~ ~~~~~~~~~~~~~~~~~~~::::j~::::~:::::::: ~ . 'ii4~i:lil-Iiri'

EE-RM-97-900 COMMENT 01E
.~~~~~~~~~~~~~. A ........

· ~,~iiii!~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~!iiiii;

*..... ....E E .Wh

X ~ ~~~~~..... ,~~~~~~~~~....iiiiiii~ ~ iiiiiiiiiii

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... ...... ....... ~ ~~~~~~~~Klllliii8.

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.... .............. ~ ~~~~~~~~~~~~~~~~~~~~~~~~~ii~~iiiii'' ................. ~ ~ ~~~~~~~~~.:iiii~(

EE-RM-97-900 COMMENT 01E
DRAFT TECHNOLOGY ASSESSMENT AND SCREENING ANALYSIS REPORT ON DESIGN OPTIONS FOR WATER HEATERS

1. INTRODUCTION

This report defines water heater product classes and discusses possible design options for improving the energy efficiency of residential gas-fired, oil-fired and electric residential storage-type water heaters. '

: .i ii: iiiii~.. 

The procedure used in this design option analysis is ba. on a 'i Tuit of Energy (DOE or Department) rule outlining process improvement measures frocess Ru 'l ier the different appliances subject to possible regulation are defined, potendtiaesign op s aeid as thnext

step in the process of promulgating appliance efficiency: :dards.iScreening fa'":si used

to determine if any design options should be eliminated fro' ii her consideration:.:'.!'..

2. PRODUCT CLASSES

Appliance features that provide utility to the .onsumer areg o.. rated into the analysis through the creation of product classes. Classes .iai'giof appliancei:pes. For example, water heaters are an appliance type, but a gas-fired stor age"wt. e.is a product class. Appliance types are 

differentiates 

segregated into separate classes to wfhi different ' iiency standards apply. DOE classes by fuel type or othrperformnce-re iii ures that provide utility to the

consumer and affect efficiency. In genea:classes are defined using data collected in discussions with appliance manufacturers, trade assoiaions, anbother interested parties.

This section specifies.the i-'duct clag..:irnsd"ed in this analysis. Those classes for which no DOE t l...icedure hii' .ecified A to ned but omitted from further analysis.

2.1 Product'l Under Ci:ieration

Cure;n a i.air---.:i- -- e.

Curreil' !iihaate rs arise:parated into the product classes shown in Table 1. The correspondiii mnimum'i ncY requirements which became effective April 15, 1991 are also listed

.... . . " . $ : -..

Table 1. Current Product Classes & Efficiency Standards

Product Css Efficiency Standard

a .ii EF ::> 0.62-(.0019x Rated Storage Volume [gallons])

EF > 0.59-(.0019 , Rated Storage Volume [gallons])

Electric EF 0.93-(.00132 < Rated Storage Volume [gallons])

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EE-RM-97-900 COMMENT 01E
Table 2 lists product classes and their current market shares.

Table 2. Product Classes for Water Heaters (31

Product Class Market Share Year

I Gas-fired Storage 52.3% 1995

2 Electric Storage 47.3% 95

3 Oil-fired Storage 0 4% i9 5

- - * ; .^ , ^:

?w^ * . .. .........; :;: ;.... ..- - . ; . ... 

2.2 Product Classes Not Under Consideration . ' | 1 :

' ''-I 8''-"'': '....R .: ...

There are other classes of water heaters manufactu.re.the Department will'not consider

in this rulemaking for reasons described below. The typeso.ter heaters of which the DOE is

aware, but for which a new standard will not be issued are.::.i et. instantaneous, gas-fired

instantaneous, and gas-fired outdoor auxiliary water heaters. ' ''-l ..

2.2.1 Electric instantaneous water heaters ......... ::8

Typical electric instantaneous water heatersdlo nit h|v|the capacity to supply an entire

residence with hot water. A 20-amp Q(22 volt) cireuit will spplyonly enough energy to heat a 3.0

gallon per minute flow by 10.30F. Th-isisnot sufficient to supply enough water at the 120 to 140 °F

range expected in most residences.ctric inistataneous water heaters are often installed as booster

heaters or to supply a single lavMatycin commialib ;,l gs such as small offices. These heaters are

essentially reiVstance heat'ing |ents install,||i |pipe.

1Thei| irecent m'ding, offered that will supply enough energy to heat a 3.0 gallon

per minute fl1ihesired teat .This unit has a peak rated input of 28 kW and thus may

not be appropriat.M s l||l househotd escially homes with less than a 200 amp electrical service.

The variable syistlem on this heater does not in itself improve efficiency.

.-..No design optios found that would improve the efficiency of electric instantaneous

water heaters. For thisi reason and because so few are installed for residential use, electric

instaneous water heaters are not included in this analysis.

±2 ;a.s-fired instntaneous water heaters

-'irX ."ed instantaneous water heaters are not studied in this analysis because of the small

number of annual shipments and because they will be covered by the same standards written for gasfired storage-type water heaters.

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EE-RM-97-900 COMMENT 01E
2.2.3 Gas-fired outdoor auxiliary water heaters

Another product class covered by the standards for gas-fired storage water heaters are gas- fired outdoor auxiliary units. Due to the small number of units sold, no analysis will be done for this product.

Water heaters designed for outdoor installation in mild climates have a significant share of the Australian market. The Gas Research Institute and a US water heater manufact:r are testing a product for the US market.[4] Because units are not yet available and ."'ilibe covered by the standards for traditional gas-fired storage water heaters, n eiarate a s l be done for this product.

3. BASELINE MODELSS .

....... ....

Baseline models for this analysis were determinei e most commonly sold models currently on the market. The features for each baseline .ledescribed in manufacturers' product literature for their standard models. The efficiency an i, gs were taken from the Consumers' Directory of Certified Efficiency Ratings ]. ..

3.1. Gas-Fired Storage-Type Water Heater. ' . ....

The baseline model gas-fired sto e-type wer he en for this analysis is a bottom- fired, 40-gallon, glass-lined steel tank a 3-iccnter fluehe inlet and outlet water connections are at the top of the tank. The in e is 34iiBtu/hr, h a pilot rated at 400 Btu/hr. It has an energy factor (EF) of .56 and a effl :.'ery cy of 6. The tank is insulated with one inch of polyurethane.foam. The ba:s..*iodel usedii ni;ysis is based on the units listed in Table 3. These are t c a identl tributors and manufacturers. The average EF for these i.. 56 an " ee rec0very efficiency (RE) is 0.76. For this analysis, the low end of the E -iR. -ranges"-1 :-d.

High i ..i the odels currently available on the market with EF ratings at the minimumffinSe'c n :fo""r tainks rated at 40 gallons. The lowest efficiency standard models of gas-f.i storage type ':~i}ith eers readily available on the market from all major manufacturers

are lisd with an EF of .5 i7. This is above the minimum EF allowed under current standards.

T:NAECA 

[6]The minimum efficie''ry for a gas-fired water heater with a rated volume of 40 gallons is 0.54. standard fr gas-fired water heaters is given by the following equation:

EF= 0.62 - (0.0019 K Rated Volume) (1)

Manufacturers have used some of the design changes that were considered as potential methods for reducing heat leaks in the Notice of Proposed Rulemaking [7] to reach these EF levels. A variety of design options are currently used, none universally[8]. Some of these are discussed here.

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While it is not directly associated with the efficiency of the product, manufacturers have

improved quality control. They are currently designing for and building better products. Examples

of quality improvements that might affect efficiency would be fewer metal to metal contacts between

feed through and the jacket, better control and placement, and fewer gaps in, the insulation, etc.

Using a longer dip tube is a low cost method of achieving a higher first hour rating. Hot water

in the upper region of the tank is mixed less with the incoming cold water as the dipube length is

increased. , : I"

Instead of getting a higher first hour rating manufactu.eirs..can afli'eati |;derate the burner

and still get the same first hour rating. A smaller burner ithe same flu i ii. n configuratia

means a higher recovery efficiency, because the same heat transfer sutce ar'easisi. dfor a lower

amount of heat. ..... ...

Plastic drain valves can save about 15-20 Btu/hr iria' isses. There is, however, a risk

of reduced reliability and the danger of leakage betweeptlai: h and plastic valve because of

different expansion coefficients. Also the cost of a plastic d"rain va".il. is than the cost of a metal

drain valve. .. _ 

Some manufacturers cover the top of theianode :i: .;insulatio.' This reduces the amount

of heat that can be lost through a gap in the i.sulationl:iiE...i ufa cturer covers the top of

the anode rod with insulation without leavg any holdien the jhis i a cost saving measure for

the manufacturer, which gives a slighitefficiency.increase. .: is, however, much more difficult for

consumers to replace the anode rodi ey dessiE Another.method of reducing the number of feedthroughs that is used by some rrnm facturers, nsists iattaching the anode rod to the hot water

outlet '.

ncurers mayi Als : sing te other echniques we are not aware of to improve EF.

The baseI....ildel EF u tis analysis is above the NAECA minimum standards to

reflect current mmodel e these increases were achieved primarily with techniques

that reduce tlieaks, rtment has dropped this design option' from further analysis.

Table 3 Current Marketlaseline Models for Gas-Fired Storage Water Heaters.

', .:., i.- . tank rated first

.^ mufacntrer iMp Number size input hour EF RE

________ ji_____s___(gallons) (kBtu/hr) rating

a ... "51-40T34-3N 40 34 63 0.57 77 [9]

" "FSG-40-230 40 32 62 0.56 76 [10]

ji'l4irte M-I-40T***N-10 40 34 66 0.57 77 [11]

Rheem - 21V40-7 40 34 62 0.56 76 [12]

State PRV 40 NORT-*** 40 35.5 62- 0.56 76 [131

baseline 40 34 62 0.56 76

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3.2. Electric Storage-Type Water Heater

inserted 

Typical 

from 

electric storage-type water heaters usually have two resistance heating elements the side of the tank. One element is close to the top of the tank. The other heating element is mounted much lower in the tank. Each element is typically rated at 4,500 watts, but

circuit. 

086

_-------....4:. ?:~iiii~?::?~:,::,

The electric resistance storage water heater chosen oXfi te b5 ae galon, glatsi lined steel tank with two 4500 watts elements. The doubleeements a erloc shat on ne element may be energized at any time. The tank is insula wth nch of fo

Manufacturer Model Number size inpi hurt EF .

American E52-50R-045D 4........... 58 0.87 [14] AOSmith DEN-52 50 5 58 0.86 [15] Bradford White M-I-50T***T-13. 5 64 0.86 [16] Rheem 81V52D 0 4.5 57 0.86 [17] State PV 52 2 R 60 52 4.5 56 0.88 [181

baseline i.' 4.5 56 0.86

3.3. Oil-FidStageTyeater

The leviatioia fl-fired storage-type water heater product features among hmanufacfortr electric or gas-fired storage products. The product descriptions presented in Table 5 are facturers product literature and the GAMA directory.[19] Not all manifacturers are listedii eGAMA directory.

For oil-fired storage-type water heaters, the baseline model considered is a center-flue model w.itioia rated volume.of" 32 gallons. The tank is insulated with 1" of fiberglass insulation. Water -.nom__.ons 

~andi 'r:- · for thiiimodel 

c.~:~cii envof 

are 

75% 

also at the top of the tank. The rated input is .65 gph. An EF of .50 are specified. These are the lowest ratings listed for comparable mitA·MA directory. The average first hour rating of 106 gallons per hour is assumed for the baseine moodel.

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Table 5 Current Market Baseline Models for Oil-Fired Storage Water Heaters.

tank rated first

Manufacturer Model Number size input hour EF RE

(gallons) (gal/hr) rating

Aero CF-32T/A 32 0.65 n/a n/a n/a [20]

Bock 32PP** 32 0.75 131 0.68: 282 [21]

Bradford White M-I-32L*OF-10 32 0.65 . 0.4 76 [22]

GSW JWF 307 32 O'65 1 76

Heat Transfer Products SJ-30 CWB 30 .. .. t5 2:: 75 .:

Lochinvar BRE 32-B 32 0.75 ia a [23

baseline 32 iii. 0.65.. . 106o:': 

4. DESIGN OPTIONS

.,:y ..::::::::: : '';::: ..

Design options are changes in water heater desig tat may haie ?i tential to save energy.

This section describes design options known atif.i:L;. : i.

The Department issued a Techni"l Suuppoi. t =D) in November 1993 that

proposed design options for increasing watif heater eFciency Many ofthe design options listed

in that document are included here alaonlWith desig'options suggested by commenters on the NOPR

and further research by the LawrenleBrkele ational L oratory (LBNL).

Table 6 shows the disig' options this analysis. Not all design options are

applicable faiisproduct classe e produc asssto which each design option may be applicable

are indi l table

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EE-RM-97-900 COMMENT 01E
Table 6 Design Options for Gas-Fired, Oil-Fired and Electric Storage-Type Water Heaters

Design Options Description gas eec oil

Heat Traps X X X

Plastic Tank X ~ X .

R-16 Insulation X . X

R-25 Insulation X xi:

Vacuum Insulation X .- :..X

Gas Filled Panel Insulation X - . .

Aerogel Insulation . X

Evacuated Panel Insulation !-:I- .. X... X :::: x x

Forced Draft .X ..,:il.lll. , - i:=

Improve Flue Baffle AX x:

Submerged Combustion Chamber ....... 'i

Multiple Flues :X: :1" X X 

Air-Atomized Burner :i . .

Sl

oo very X X

Flue Dl..' 3-- ........ X

Flue pa -rBOperatehd) X

Jdirect Heating (Sie rHeater) X

. Two Phase Thernisiphon X

Flue Gas Dilutiio X

on X

u:t.pe.. ed BIgnition x

Thermophotovoltaic Generator X X

Thermoelectronic Generator X X

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EE-RM-97-900 COMMENT 01E
Condense Flue Gases X X

Pulse Combustion X X

Condensing Secondary Heat Exchanger X X

Add-On Heat Pump X

Return Air Heat Pump _____ x

Integral Heat Pump

Submerged Combustion

Directly Fired " X

Off-Peak XU"

Solar Pre-Heat . ' ii.X x::

Drain Water Heat Recovery X X

Tempering Tank . X X

Regular Maintenance . Xi X X X

Sediment Removal Features .X :X X

g A~~~id: i::; .... ^i s...:... . . i.i.:i' 

Some of the design options insjtbile 6 are pliminated iom further consideration (later in this

report) if any of the following criti isted ii'dte Processrtule are not met[25]:

1) .:Tjinologica! ~bf. .i.iy..y. . . iorate :'hnolg* d ini omercial products or in working prototypes will be

..... ^Ilidered tech Illcally feasible."

2) Practi t:i;o ManuJft.ut nstall and Service.

.. '..M::io n of technology in commercial products and reliable installation

. and serv"i"n" '":fit:chnology could be achieved on the scale necessary to serve the

relevant i the fi time of the effective date of the standard, then that technology

... l will be considered practicable to manufacture, install and service."

::.i 3) No adverse.impacts on Product Utility or Product Availability.

i 4 Niiiiii:er;i.eN. I se Impacts on Health or Safety.

t hi" e reasons for eliminating a design option shown in Table 6 (or keeping for further

consideration) are discussed in the individual descriptions of the design options outlined below. The

design options that are not recommended for elimination in this report will be further analyzed. The

efficiency and cost of design options not eliminated, and combinations of these design options will

Draft screen.00S June 23. 1997 B-8

EE-RM-97-900 COMMENT 01E
be 

reasons. 

analyzed. 

In certain 

Later analysis may reveal which design options should be eliminated for economic 'cases the proper application of a design option may require substantial modifications 

performing 

to other elements within the water heating system (e.g. chimney). The cost of these modifications will be included within the future economic analysis.

Comments 

Included in the discussion of design options are concerns raised bv commenters on the NOPR. do not necessarily exclude a design option from further analysis but descibe issues that are affected by a design option and should be taken into consideration fao~irther:analysis.

Heat Traps .. i iiiiii

heaters. 

Heat 

Without traps 

some 

are anti-convection 

method 

valves installed att,.e inletad outlet of A.e t"" water to prevent it, convectiona -ioi.l develop inside I i s leading out of the water heater. These convection loops are slo.iOw of water driven by the different densities of hot and cold water. Buoyant hot water rises .in'e seide of the pipes leading out of the water heater. As it flows up the pipes, heat is lost to:the surrotndiatir. When the water cools off, it increases in density. The cooler water then sinks.b¢c -de along the of the pipe and back into the water heater tank.

Anti-convection valves are one-wayvalves w fi':ii h.. water inlet pipe into the tank from the cold

transporting 

and out of the tank intofthe hot water outli" but keep convection loops from hot water out of the tank. vention.heat trap are currently made in two styles. The

it 

first 

in place, 

style has 

until 

a floating 

water 

plastic ball th.itblocks thecold water. ilet. The buoyancy of the plastic holds is drawn. TIforcees 

as enters water the tank. Th~:Zec:"~ sti' g enough to push the ball out of the way : - trt style the bllot wa

as water enters the tank. Theecond style is e e hot water outlet. In this heat trap, the ball is more: d ia::.n wa a :ter. ::t wi..ght of tf lls the outlet until hot water is drawn and the water 

the inlet 

pinlet' out Fi ea 6] A smabypass channel is left for water to escape back into line ank as.._after a large draw fills the tank with cold water.

Other.:heat" ":sins :

[27], 

also Iha"been invented and produced. These include U-shaped pipes flexib i-'ls '[ flapssprings, and other mechanisms.

.l:he Department : :: i:::: that this design option should not be screened out.

.iic Tank :i

At~ least....manufacturer 

i 

is making water heaters with plastic tanks. The technology, a

to::th F o' ...... '"':::'"'''ded polybutylene inner tank with a filament wound fiberglass outer tank, is similar

compared 

: 

to metal, 

:gy used to make tanks for water softeners. [29] The lower heat conductivity of plastic reduces the amount of heat conducted through the tank wall to the insulation and to 

heaters, 

the feed-throughs. 

or 

This technology can not be used with standard center-flue gas-fired water oil-fired water heaters. The plastic can not withstand the high temperatures produced by the flames. This technology is used with electric water heaters without any problems. Side-arm water Draft screen.005 June 23, 1997 

B-9

EE-RM-97-900 COMMENT 01E
heater and heat pipe technologies can avoid flame temperature problems with gas-fired water heaters.

Side-arm gas-fired water heaters with plastic tanks are currently available. [30] Plastic tank water

heaters using heat pipes to transfer heat from the burner are expected to be on the market by the end

of this year. [31]

The Department believes that this design option should not be screened out.

R-16 Insulation

The jacket insulation on the baseline model of gas ain ectricijc : eaters is one inch of

foam insulation. The baseline model for oil-fired water heiars uses fibe lasin sulation. The R-46

design option increases the insulation thickness to two inche ofoam ins'iiation : ii"e si de:ahd

top of the tank. All manufacturers offer both gas and electri nmodels with thicker le::::liii lation.

The Department believes that this design option shiA not:fbe screened out.

R-25 Insulation ' .

This design option uses three inches of foam i :''' atni around ':ides and top of the tank.

The costs and energy savings are calculated a:?.mc .anges rei: feom the R-16 (two inches of

foam insulation) design option. This design onin increstlof water heaters four inches

from the baseline. Additional installation csts will biadded t i nt for those cases where water

heaters are installed in tight locations tiat require :emodeling to fit. There will also be an increase in

shipping costs as fewer heaters willfitin a truk etc.

The Department beli e .tlat this dSioinl'shoud not be screened out.

Vacuumi ll .....

A "hardaiii iwith inftetiai rctive surfaces is a very good insulator. It has been used

for years in The'sibtl"' e" and Dewa'-tnks for cryogenic applications. While this technology could

be applied:t'wat"er heates th-lDepartment is not aware of any attempts to do so.

'.The Department beie:esithat this design option should be screened out due to problems with

proditt availability. :| ' :

s9Flillled Panels :..

:iijIii^'" :'P'aneis "' (GFP), are thermal insulating devices that retain a high concentration of a

loNiii'::.iv:ity gas. at atmospheric pressure, within a multilayer infrared reflective baffle. The

thermal performance of the panels depends on the type of gas fill and the baffle configuration.

Calorimetric measurements have shown total resistance levels of about R-12.6 for a 1 inch

thick krypton panel, R-25.7 for a 2 inch krypton panel, and R-18.4 for a 1 inch xenon panel. GFPs

Draft screen.005 June 23, 1997 B-10

EE-RM-97-900 COMMENT 01E
are flexible. self-supporting and can be made in a variety of shapes and sizes to thoroughly fill most types of cavities. [32]

The Department believes that this design option should not be screened out at this time but seeks additional information on this design option.

Aerogel Insulation

insulating Aerogels properties. 

are transparent, low density, and highly porous mater i very good thermal I >

New manufacturing processes have been developed that ca dutb e blankets or

been 

clamshell forms of this material. At cryogenic temperaturs -valueser inch greai .40 have

also been 

observed 

measured. 

at high vacuum. R-value per inch greater ambient pressien have

R-20 

[33] Commercial applications of thisi `1pgy with a high vacuum achieve in a 1" thick panel. [34] i.

The Department foam in i~!i~ii?~iiii:i "'j:~'~ W..:."'": .... believes that this design option should not e screened out at this time but seeks additional information on this design option.

Evacuated Panels

insulators 

In addition to aerogels, other Mai s witilightwe en structure can create very good

company manufactured 

at "soft" or low vacuumi. The materials canie enclosed with metals or plastic. One panels for in refligrtors. T design used hermetically sealed stainless steel skins to srround a layerf secial higW fiberglass A vacuum (10 ' torr) is drawn in this pr s 

the vacmzm p5) rigid fibea eps the vacuum panel from compressing with

Other tedj insulation panelsfeature fine powders contained within an envelope composed of teP wt.erse an ffer five to ten times the R-values of standard fiberglass or foam insulac u iiie. 3, -

.Jyhe Department i s that this design option should not be screened out at this time but seeksadditional informationn on this design option.

FDraft Draf

Howevr, 

Sevua anufacturrers l are currently making water heaters with induced-draft blowers.

increase 

it's feature is usually added to allow sidewail venting and may not be accompanied by any in flue baffling.

Using a fan to force the flue gases through the baffle with either an induced-draft blower (downstream 

Draft 

of the water heater) or a forced-draft blower (upstream of the water heater), often screen.005 June 23, 1997 

B-ll

EE-RM-97-900 COMMENT 01E
called power vent, can increase the recovery efficiency and reduce the standby flue losses. The offcycle flue losses are reduced by the additional restrictions to air flow from both the blower and the

increased baffling. Increased recovery efficiency from this design option may necessitate relining vent

systems.

The Department believes that this design option should not be screened out.

... ii

Improve Flue Baffle , .:

.. 2 .,-.

The standard flue baffle is a twisted strip of metal ,'ied int"i fithat increases the

turbulence of flue gases and improves heat transfer to the .als of the fleiiiO::: manifacturer: uses

a flue with many small rectangular fins attached on the insie surface i'J!their mi defficiency mael

The arrangement and size of these fins increases the reco;::ry effieiecy of the wti:;: ' iierOther .

baffle configurations that increase recovery efficiency are|| -. .. ilable. i -

If the recovery efficiency is too high, water heaters wit:i iign option vented to masonry

chimneys or other older venting may cause problems. In tihat case hhmneys must be relined to

prevent problems caused by the condensation of flue gases. To avoid ms from condensation

it is also possible to use sidewall venting. A?:li} ...

Potential health and safety proble.m associat ' effi ciencies that are too high

will be addressed by increasing the ins.flation cQ.t to ac iifr modifications to the venting

system. This design option will be spit to threeidesign options, a slightly improved flue baffle, an

improved flue baffle, -and a greatly imov'ed flueaiffe. Thedfeails of the geometry are not specified.

The slight improvement in the flue:i"te woulidve an R of around 80%. and is assumed to work

with existingvent systems. teimprovedl: wuld have an RE of around 82%, and is

assumed ti vent.re venit.i n a sigrii mount of installations. A greatly improved flue

baffle is:assm to have ::B.. and would require power venting for safe operation.

:bis~ " -~i'bi::. >::: ha v . .. . ":::eo:pera:t:i:on.*::::.:::: The Dep ibelieves 'i^design option should not be screened out at this time but

seeks additionai oon ' : -n on thisi'n option. ..... .....~iii ' " ~i .>b: ::,. "%'"

Submerged CombustioCi0mW r

The combustion chamber in a standard gas-fired storage water heater is below the water tank.

Thi bottom of the taki 'is suspended directly above the burner. The sides and bottom of the

... iustion chamber are not surrounded by water. By inserting the combustion chamber into the

e morg 'atnk. the combustion energy can be recovered. Standby losses are reduced somewhat

"b" s"' ei".ictions on the air flow through the combustion chamber and flue.

This design option can increase recovery efficiency sufficiently so that condensation is likely

to occur in venting systems that are not double-walled sheet metal. To avoid problems caused by

condensation on other venting systems, masonry chimneys must be relined or sidewall venting must

be used. If vented properly, no health and safety problems exist.

Draft screen.005 June 23, 1997 B-12

EE-RM-97-900 COMMENT 01E
The Department believes that this design option should not be screened out.

Multiple Flues

the storage 

This design option uses three smaller flues in place of one large central flue in the middle of

is a consequence 

tank. 

of 

The greater surface area of the flues yields an increase in recovery efficiency. This the increased surface area for heat exchange between the flue gasesand the water in the tank. One manufacturer 

heater. 

is currently offering this design option in a residentiu gas-fired water

a

The Department believes that this design option sh l be s .. t.

Air-Atomized Burner .... ' i ..........:

create a 

This 

spray 

is 

of 

a 

fine 

different type of burner for oil-fired equipt nstea d of relying on pressure to oil droplets prior to combustion, This design allows better 

this s stream of air to atomize oil

conventional 

control of droplet size and rixing w i t wer oil flow rates than burners. Downsizing the burner with the sameflue and ba-goetrv will give a higher recovery efficiency. The combustion process is AlW Nth this. uier.

Working water heaters have been m with sp Therewould beno impacts

seeks add:i'..... informatuiorhs deig o ...... m

Slow Reco ry iiiiii:..

* - m . .No - .. There be no im pact

ratio of heati 

Redi 

fer 

while ng fle baffle and tank geometry the same will increase the

input means 

' s per BTU input thereby increasing the recovery efficiency. The lower the recovery: i s lower. The first hour rating would probably be reduced as well, although some of this firs: ihorating reduction could possibly be offset by changing the dip tube design.

"U" Tube Flue

Draft crn.5 June23. 1997 

B-13......

.". There should no pro with blem technological feasibility or impact on practicabilit to

Ar eaendtierviceoexcept if the recovery oft erecb y increas me es to of point c ausin g l~input:iiii!":- tmg systems. No impacts adverse woul d be on expected health and safety.

The Department that believes option this design should no t be screened out at this time but additional seeks on information design this option.

"U" Tube Flue

Draft scrcen.005 June23. 1997 

B-13

EE-RM-97-900 COMMENT 01E
One commenter to the 1994 NOPR mentioned an old water heater design that uses an

inverted U-shaped flue within the tank of the water heater. This design could increase the recovery

efficiency and would reduce standby losses. Unfortunately no working models are currently available

and it is not clear whether it would meet modem safety standard. There is also a lack of working

prototypes.

The Department believes that this design option should be screened out dueitb uncertainty

about availability and safety of this design option. ;^ 1

Flue Damper (Electromechanical)

Flue dampers are offered by several manufacturers a? an option;n co'mml iater hder.

These dampers are electrically actuated dampers mountdi.at the tip of the flue. :!T d'i| s are

opened when the water heater is firing and closed duri |ffiicle. When the da :iis closed,

standby losses by air flow up the flue are reduced. Safety inite are " required to assure the damper

is open before the burner can come on. It should be noted tha lii:de. in option requires electricity

to operate a gas-fired storage type water heater. .

Because these devices are currently bei. .|.'|i com.m cpm erer heaters, this design

option passes all the screening criteria. It shouldi'noted i l iadditiot the increased installation

cost for electrical supply, maintenance costls re expe.ted o| hi.i'

The Department believes that.s design iption shold not be screened out.

Flue Damper (Buoyancy Operaed) Y

Thij: s.kd.amnper ivs: ::';¥ery ligh' ":::: l:uminum dome-shaped poppet that slides up and

down 'r'e placei" " ::: ofthe flu of a gas-fired water heater. The buoyancy of a cycle

combustion ... lifts theii l alowing flue gasses to enter the venting system. Working

prototypes ha ve: ilt and tes iid |AGA.

This`ifl`"lg otioni ould reduce off-cycle standby losses, but would have no effect on

recoverefficiency. This ' i er may not work with high RE water heaters as there may not be

enoug 'waste heat in the eO .ion products to provide sufficient buoyancy to lift the poppet. There

aren' known obstacles i this design option, although it has not passed safety certification yet.

The Department believes that this design option should not be screened out at this time but

s'ti:ik tionalinrmtation on this design option.

I':" ''""'': e (Side Arm Heater)

This design option avoids the large flue losses by removing the flue from the center of the

tank. Water is withdrawn from the bottom of the tank and heated in a small separate heat exchanger

over a burner. Water is returned to the top of the tank. A small circulation pump moves water

through the heat exchanger when the burner is on. The burner has electronic ignition. Auxiliary power

Draft screen.005 June 23, 1997 B-14

EE-RM-97-900 COMMENT 01E
can be supplied by a low-voltage plug-in transformer. Further reductions achieved by using electronic in standby loss can be ignition on the burner.

electronic 

There 

ignition 

is a commercially available water heater using this design option in combination with and a plastic tank.

The Department believes that this design option should not be screened out:i

Two Phase Thermosiphon (TPTS)

working 

This 

flue 

is a heat pipe like mechanism to transfer heat fr'omI the burna ge tank. Tihe is partially vaporized at the evaporator whi is mountedver thThe.v or

At 

along with some of the heated liquid is propelled to the :denser:ich is insi if'""' ank.

restricted 

the condenser, 

tube to the 

the vaporized working fluid is conde '"ri:ains back throurgiaate evaporator, where it is reheated. The -:':iciiOprevents the heated vapor and liquid from flowing to the condenser on the return path there is very little heat transfer through the TPTS system. This reduces standbyosses teat

Working prototypes have been developed A major':heater manufacturer planning to bring a version is to market soon.. .. ::

seeks additional 

The Department believes that th esign se screened out at this time but information on this eAin option .ai iox -.'.:.. . ... ;

SA ufactaking with induced draft fans that in addition to prior 

pu~lling 

to 

t 

ve 

sbaIon 

additio 

prd through the water heater, also draw excess air into the flue gases

a low enough tpefj 

drawn in cools the flue gases leaving the water heater to

problems rwithob 

so thatSt 4lastic piping can be used for venting. This eliminates any

masonry 

astic pi is often cheaper and easier to install than sheet metal or chimneys" H

hile this design es not necessarily wTh design 

increase water heater efficiency, when combined options thatr e crease recovery efficiency, it can help avoid venting problems.

uThe Departmebelieves that this design option should not be screened out

Intermittent or electronic 

is the pilot replaced with 

ignition systems can be installed to replace a standing pilot. Not only

This design option 

new equipment, but so are all the required burner control and safety devices. requires electricity for the gas-fired water heater. There are three different technologies available to electronically ignite the burner. These are hot-surface Draft ignition. spark-to-pilot screen.O05 June23, 1997 

B-IS

EE-RM-97-900 COMMENT 01E
ignition, and direct-spark ignition. The hot-surface ignition heats a ceramic oxide element to ignition

temperature using line voltage. Both spark-to-pilot and direct-spark ignition use a-spark to ignite the

gas. The spark-to-pilot ignites a pilot which in turn ignites the burner. The direct-spark ignition uses

a spark to directly ignite the main burner. Both of these designs can be built to use low voltage

supplied by a 24 volt transformer. Low-voltage electricity can be supplied by a 24 volt plug-in

transformer. A plug-in transformer reduces wiring and other installation costs.

It should be noted that a large portion of the heat from the pilot light . elpst. maintain water

temperature in the tank. Without a flue damper or some other restriction n-ycle flue losses, the

reduction of gas consumption is small. The cost of the electri i for th: ignition, and the

standby losses in the transformer, is more than the cost of the gas that is '. :having a pilt

light. This design option used alone will actually increase'Ibtal energrConsum'ion' Mpare a

standing pilot. .

The Department believes that this design option s ' l tybe screened out. .... . ....

Interrupted Ignition · iI

The spark ignitor for oil-fired burners is us 'l. n when e"ite burner is on. With the

right controls, the spark can be activated onlyi '':s':i:'me is established. This design option

not only reduces electricity consumption, but i:so reduces ' i iiosts , because the electrodes

do not have to be replaced as often. . .

The Department believes this desig. option shuild not be screened out at this time but

seeks additional information on t'ihadesign " q.n. 

Thermon:poA.! taic G e*a'-

A th*p voltaic" -i ter uses a special light-emitting burner coupled with silicon

photovoltaic ce'i'. 'G'erate " auxti ' y "i||wer torun a fan, electronic ignition, controls, and charge

a battery. This ::.erquire i"*Is mn iof auxiliary electrical supply, while offering the efficiency

advantagesait eiectrrc.t i i-on and forced-draft combustion.

.The Department :iSll-ded development of prototypes of this design option.

The Department blieves that this design option should be screened out due to concerns about

:itiacticability to Manufacture.

TI '-'-' ,nei:t aGenerator

Another method of generating electricity at the water heater that is based on thermocouple

technology. Thermoelectric generators are available, but none have been used in water heaters.

Draft screen.005 June 23. 1997 B-16

EE-RM-97-900 COMMENT 01E
The Department believes that this design option should be screened out due to concerns about the practicability to manufacture.

Condense Flue Gases

To extract the maximum heat out of the fuel of a gas-fired appliance, the combustion products in the flue gases must be condensed. To do this in a storage water heater, the flue musthbe lengthened by coiling it around inside the tank. The flue exit must be low where it can;:-wntact h:' coolest water in the tank. The flue gases must be forced through the water heater, :' draft provided by buoyancy forces is not strong enough. Three manufacturers crtly ma eheater using this technology. It is typically designed to provide both dome:st:hot .ndihating. water. I

The condensate in flue gases is acidic. Special Sting sytms must be:tj'. lf: can handle this condensate, and the condensate must also be' e':iisafely. The installai ost in this analysis must include the cost for adding electric service, li conduit, re-venting, and adding a condensate drain. The high sulphur content of fuel oil means':, tc densate is much more acidic for oil-fired equipment. This design option has not been demonstrat4. i r::: t!fired storage type water heaters. . .....'.:.. -wi i :'i: ''

water 

The Department believes that this desgn tid not bScreened out for gas-fired heaters. The Department believes t.i: this design p be screened out for oil-fired water heaters due to concerns about the:practicabit' to maJ re. -

Pulse Combustion .

Pulse.combustion burers erate onii ronating pressure waves that alternately rarefy the tion cha j ing a eir mixture into the chamber) and pressurize it (causing .e. cormp0 .reo the mixtiire to its flash point). This process is initiated by a blower s-up-i..... ntieal fuet niuxture to the combustion chamber. The mixture is ignited with a spark l i.et b rtmes atiiis produced, the process becomes self-sustaining. Pulse frsequencies areil r 10e ''of s per second . Pulse combustion systems feature high heat transfer 

installedinside. 

ra,,'are 

Americ'"'iAiociation 

c ':'i.'.oself-venting, and can draw outside air for combustion even when Laboratories (AGA Labs) built several prototype pulse combustion water heaters-'asp:.'fart of a study of pulse combustion residential water heaters. [39]

This technologyhas not been developed for oil-fired equipment.

T:.....e De..:ent believes that this design option should not be screened out for gas-fired

wa hii" ""'"' t-'is time but seeks additional information on this design option. The Department bel.iesi:... s design option should be screened out for oil-fired equipment due to problems with product availability.

Add-On Heat Pump

Draft screen.005 June 23. 1997 

B-17

EE-RM-97-900 COMMENT 01E
This design option involves a separate heat pump that can be attached to an existing electric

storage type water heater, A small pump circulates water from the tank, through the heat pump.. This

design option could also theoretically be applied to either gas-fired or oil-fired storage type water

heaters as well. [40]

The Department believes that this design option should be screened out due to the lack of

demonstrated practicability to manufacture, install and service and lack of product.availability.

Return Air Heat Pump .:W "

Another technology somewhat similar to add-on ;eat pumps hloae at porator in the

return air duct of the household heating and cooling '.isystem. RieranM i|i edt......he

evaporator.[41] 1: I,, 

The Department believes that this design option s h

uldbe screened out due to the lack of

demonstrated practicability to manufacture, install and seraicek. l k of product availability.

Integral Heat Pump

The integral heat pump uses a heat|ie.xchangeth.. .buit :ia the| inner wall of the tank as

the condenser. This design increases the'efficienc tof the cohi er and eliminates the need for a

pump to circulate the er. Tshis des ion i based seon onwater. ater heater currently on the market.

[42] .:'. :

.The Department beeehat this Al should be screened out due to the lack of

demonstr atdracticabily ttiaufactur rt- aid service and lack of product availability.

Submerged C'~whiion

' it~te r ~ e fll ^ ^ | | | | | !6 ( o w '

<::: ^ 1 1 11s,. ..

In this 4ig|the flue.products are bubbled through a small volume of water by the

pressure fro eburnie r. This small amount of water is heated by direct contact with the

flame and flue products. -tllatewater is re-pressurized by a circulating pump and returned to the

storage tank. . g

... .i A potential healthiproblem is the contamination of domestic water by the flue products. This

di: .may conflict wit plumbing codes. [43]

*'il.. .erti" " -iment believes that this design option should be screened out due to potential health

probleis:' :s:sed by this design option.

Directly Fired

Draft screen.005 June 23, 1997 B-18

EE-RM-97-900 COMMENT 01E
In this design option, water is sprayed through a series of baffles above the burner. Flue products 

returned 

are in direct contact with the water, which is re-pressurized by a circulating pump and to the storage tank.

design may 

A potential 

conflict 

health 

with 

problem is the contamination of domestic water by the flue products. This plumbing codes.

problems 

The 

caused 

Department 

by 

believes that this design option hould be screened dueopotential health this design option.

Timer Controlled

This design option limits the time of day when the ments heater may 

.n electric t ater

management 

be energized. These are most often use.d.. of eectc tind side

the water in 

programs for load shifting Field tests show a f :i e"t energy savings, from allowing the tank to remain at a reduced temperature .fRi il day.

The Department believes that this design pi uld d out at this time but seeks additional information on this design optioni.. .i,

Solar Pre-Heat 

iii.

This design option uses solart cllectors. ~as pre-heas to a standard electric storage type

This a heat es hanger to recover waste heat from the drain. In effect this becomes 

wfossil-fif 

a. 

water 

ter 

heaters T 

standard 

eearirem 

electric storage type water heater, but could be used with a few designs currently available.d c

. t be screened out at this timbu

The Department 

seeks additional information 

lieves that this design option should not be screened ou.:t at this time but on this design option.

Drain 

!. .... o"er .....

Teprain T-:k

A tempering tank is an un-insulated storage tank plumbed in the water line before the water heater. When it is installed in a conditioned, or semi-conditioned temperature to the ambient temperature. space, it will raise the inlet water d wi b th Draft scrcn.005 June 23, 1997 

B-19

EE-RM-97-900 COMMENT 01E
The Department believes that this design option should not be screened out at this time but

seeks additional information on this design option.

Sediment Removal Features

Several manufacturers offer models with dip-tubes designed to create turbulent water flow

that prevents or limits the build up of sediment on the bottom of the tank. Ti.s'may reduce

degradation of efficiency over the life of the water heater. A ': .. * : 

The Department believes that this design option sh ou[liot be :i ::ut at this time but

seeks additional information on this design option. ....... . ::

4. CONCLUSIONS ..

For previously stated reasons, the design options :ina were eliminated from further

consideration.

.::Draft . June .: c . 23, ,,005 .... B c....::,"'- : : : :>:','':::::' ........ ..

...........

Draft screen.005 June23, 1997 B-20

EE-RM-97-900 COMMENT 01E
Table 7. Design Options Department Proposes to Eliminate from Further Analysis

Vacuum Insulation

"U" Tube Flue

Thermophotovoltaic Generator

Thermoelectronic Generator .

Condense Flue Gases (oil only)

Pulse Combustion (oil only)

Add-on Heat Pump

Return Air Heat Pump ..... iiiiji&.......* ;

***

Integral Heat Pump

Submerged Combustion

Directly Fired

. ... * ....... S irii

Table 8 shows the design optis remaii' g for furtfr analysis.

Table 8. Remaining Desi Otions. n :

Heat 'Ti i

R16 Insulation

R25 Insulirion "iiiii:i

Gas:,illed Panel InsulatiO

gel Insulation

ated Panel li'ation

Improve iFue Baffle

Submerged Combustion Chamber

Multiple Flues

Draft screen.005 June 23, 1997 

B-21

EE-RM-97-900 COMMENT 01E
Air-Atomized Burner

Slow Recovery

Flue Damper (electromechanical)

Flue Damper (buoyancy operated)

Indirect Heating

Two Phase Thermosiphon ,

Flue Gas Dilution .' ,::: . , 

Electronic Ignition . | ' ' liiii:ii

Interrupted Ignition ..

Condense Flue Gases (gas only) . . . . R,,R :

Pulse Combustion (gas only) .. .. .

Timer Controlled '

Solar Pre-Heat

Drain Water Heat Recovery System:: f .. ;'

.::...

Tempering Tank .f ,

Sediment Removal Features .. i

Draft 005 June23,1997 . ... B-

* '. >,.>lss,;S:g :::

Draft screen.005 June 23, 1997 B-22

EE-RM-97-900 COMMENT 01E
REFERENCES

1. U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (U.S. DOE).

1996a. Energy Conservation Program for Consumer Products: Procedures for

Consideration of New or Revised Energy Conservation Standards for Consumer Products,

Notice of final rulemaking.. Federal Register. Vol. 61 No. 136, July 15, 1996. pp

36974-36987. [http://fr.counterpoint.com/fr/1996/0715/00014.html]

2. U.S. Department of Energy, Office of Conservation and Renewa lergy (U.S. DOE).

1990. Energy Conservation Program for ConsumeAro OductsPiWR le Regarding Test

Procedures and Energy Conservation Standards fa* ater HeRegister, V.

55, No. 201, October 17, 1990. pp 42162-4217 7^ Aixi

3. US Department of Commerce, Bureau of sus, Economicsi Statistics

Administration. 1996. Current Industrial Repor usehold Appliances -MA36F,

Annual 1995. [http://www.census. gov/industry/ma3.l

4. What 's the Latest Splash in Water Heating?, GRID Gas Ritu te Digest, Summer

1996, Gas Research Institute, Chicago, IL.X, ......

5. Gas Appliance Manufacturers Asso'iation,nsu r' Directory of Certified

Efficiency Ratings. Arlington, VA iOctobere196

6. Code of Federal Regulations CF 430.32 ergy Conservation Standards and

Effective Dates. [http://cfre nterpoi ucom/cfr/L i 997/0228/0002859.html#§ 430.32]

7. U.SDOE. 1993 Oiitp. I-6

8. iions 1ii Lannes adford-White Inc., Middleville, MI, (12/16/94);

Ml M xttin, Cafi3i t Ei^ergy Commission, Sacramento, CA, (12/19/94); and Larry

Weinga i| ental E|Monterey, CA, (12/15/94)

9. AmiGoup1994. Residential Gas & Electric, RGE-1 1/94, Johnson City,

9.

10.' A.O. Smith WateiPriducts Company, 1994. Energy Saver Gas Residential Water Heaters

:il FSG, FSGL, FGiH, FSGT, A 713.1, November 1994, Irving, TX.

.Bradford W.e Corporation, 1996. Full Line Water Heater Pocket Catalog, Rev 8/96,

12 .'R^i; em Manufacturing Company, Water Heater Division, Residential Gas Water Heater

Product Guide, 6-93 BP Form No. 1366, Montgomery, AL

13. State Industries, Inc. 1994. Residential Gas Water Heaters, Censible, copyright 1990, STG

5/494, Ashland City, TN

Draft screen.005 June23, 1997 B-23

EE-RM-97-900 COMMENT 01E
14. American Water Heater Group, 1994. Residennal Gas & Electric, RGE- 1/94, Johnson City,

TN

15. A.O. Smith Water Products Company, 1994. A.O. Smith Full Line Catalog: Residential.

Commercial Water Heaters, Boilers and Storage Tanks, Form No. CPD-9150E 60M-59A,,

1994, Irving, TX

16. Bradford White Corporation, 1996. Full Line Water Heater Packet Catiog, Rev 8/96,

Ambler, PA. .i ::!.

17. Rheem Manufacturing Company, 1995. Water "Divisioi'::"tiial -H'er Gas Water

Heater Product Guide, 10-95BP Form No. 105-6.Montgom A L::. ......

18. State Industries, Inc. 1990. Residential Electrici :.er Heters, Cerinsiblie, iv g: 1990,

STE 16/1-90, Ashland City, TN :

19. GAMA, 1996, Op. cit. .....1^ .i..!iiiB:::,,

-. * . .."...R,''..I.'. " ''".'

20. Aero, 1996. Water Heaters, High Efficiency Oil., red Waterl :gWH 03/96 30M DKT

2641, Mississauga, Ontario, Canada ... S

21. Bock Water Heaters, 1996, Oil Wat~ ' Heate"rs 1-t, Madison WI

22. Bradford White Corporation, .1996 Ful.iLine Waeir' Heater Pocket Catalog, Rev 8/96,

Ambler, PA. .

23. Lochinvar Corporation, il93, Res a .-,:"Fired O- Water Heaters, Litho 2M 10/93,

Na..:i.e, TN ii .......

24. t "J'e-m:nent of'- Oice of Energy Efficiency and Renewable Energy (U.S. DOE).

199J':":St:uppo . : " : Energy Efficiency Standards for Consumer Products:

Room AIr:i"':""Mers. Wa: i" ters, Direct Heating Equipment, Mobile Home Furnaces,

'Kitc i"i'i : -. ..ens, PotHeaters, Fluorescent Lamp Ballasts & Television Sets. No.

... DO'E-000II;'"::p- . by Lawrence Berkeley Laboratory, Energy Analysis Program.

November 1993 Vl3'F

25' U.S. DOE. 1996 i Op. cit.

M. U.S. DOE 1.9. Op. cit. p 1-5

27.ifli."NieiD. Ned. ed.. "Simple Heat Trapfor Water Heaters", Energy Design Update, vol.

'.i4lno. ' 10, October 1994, New York, p14.

28. Harvsy, Jane Allison, "Making Your Water Heater More Efficient", Home Mechanix, March

1994, p 14

Draft screen.005 June 23. 1997 B-24

EE-RM-97-900 COMMENT 01E
29. Rheem Manufacturing Company, Water Heater Division, "Marathon High Performance,

High Efficiency, Lifetime Gas Water Heater ", form no. 101-41, 10-93 BP, Montgomery, AL.

1993.

30. Rheem, 1993. Op. cit.

31. Communication with Ron Swenson, TPTS Development Company, Santa Cru;:CA, (3/4/97)

32. Griffith B.T., Arasteh D., and Turler D., Gas-Filled Panels: An f.4:t WApplications in

the Building Thermal Envelope., Lawrence Berkelerationa. :atory, LBL-38093,

October 1995, Presented at the BETEC Fall Symposi u, Washi . ieC, November 1:4i

1995. <http://eande. bl. gov/BTP/papers/38093..pdf:'B i e a'so

<http://eande.lbl.gov/BTP/pub/INpub.html> .ii ..

33. Williams, B., Technology Opportunity: Aerogel-Ba"" rinsulation, NASApril 1997,

<http://technology.ksc. nasa. gov/WWWaccess/Oppoi i..el .html>

34. Glacier Bay, Inc. Super Insulation Panels. BARRIER 20Mii... 1 1997, San Mateo, CA

<http://www.glacierbay.com/BARRIER.htiii m... :,ii, 

35. Vacuum Insulation a Reality, Environmental B bilSi&Nws, vol.-4, no. 1, January/February

1995, : ..i' . ^ ........

<http://www.ebuild.com/Arc hivcves "roduct:-Review /AUR VacuumInsulation.html> _ 

36. ORNL, Powder-Evacuated ias, OaiRidge Natnal Laboratory,

<http://www. orn.gov/%7'k/succe ep.htmit

37. .. ob~ Therm"ls'"j"WaerHaterater <http://ecotopia.com/tpts.htm>

38. Unitei:^':titi.: atent 439.-3,66.

<http :// "r t" .gov/c "i:fetch4?/mount2/PTO/INDEX-+PATBIB-83+0+2 1797+4

+0+-,27 iS*1+J IN%^runes>

39. ..ifThrasher, W.H., ""|Combustion Residential Water Heater, Prepared by American Gas

Association Labori o , Cleveland, OH, for Gas Research Institute, contract no. 5080-345-

0369, October, 986

: j. .Heat pump w.er heater models B 108 and WH-6BX manufactured by E-tech, Atlanta, GA.

: : :iilka: : A , i: P.B:i ; :: ;

4. " " ir Conditioning is developing a heat pump water heater of this type.

42. model #TS-HP-52 HR, manufactured by DEC International, Therma-Stor Products Group.

43. International Association of Plumbing and Mechanical Officials, Uniform Plumbing Code, 10,

section 1002, Walnut, CA, 1991

Draft screen.005 June 23, 1997 B-25

EE-RM-97-900 COMMENT 01E