State water heaters 317913-000 Quick start guide

Printed in the U.S.A. 0210 317913-000

A TECHNICAL GUIDE TO

DESIGNING ENERGY-EFFICIENT

COMMERCIAL WATER HEATER

SYSTEMS

12345678901

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

12345678901

2

l. Introduction To Commercial Water Heating Pages

Parameters .................................................................................................................................... 2-3

What is Hot Water? ........................................................................................................................ 3-4

Evaluating Water ............................................................................................................................ 4

ll. Principles of Sizing

Hot Water Demand ........................................................................................................................ 5

Profiles of Operation ...................................................................................................................... 5-6

lll. Equipment Performance

Recovery Capacity Tables.............................................................................................................. 6-7

Storage Capacity And Tank Efficiency............................................................................................7

Gas and Oil - Fired Tank Type Heaters.......................................................................................... 8

Electric Tank Type Heaters............................................................................................................. 8

Auxiliary Tank (Unfired)................................................................................................................... 8

Heater Recovery Plus Storage Tank Equals Demand .................................................................. 8

Heater Recovery And Storage Tank Performance Comparison ................................................... 9

When Using Electricity to Heat Water ............................................................................................10

Estimating Water Heating Costs ................................................................................................... 10

lV. System Types And Application

Design Objectives.......................................................................................................................... 11

System Types ................................................................................................................................. 11

Tank Type Water Heater Systems Using Gas, Oil and Electricity.................................................. 11-12

Creating The Successful System ..................................................................................................13

Sizing Without Prepared Information ............................................................................................. 13-14

One Temperature System .............................................................................................................. 14

Two Temperature System .............................................................................................................. 15

Field Assistance............................................................................................................................. 15

Thisguideis differentthan mostproduced bythewater heatingindustry. Insteadof justreferring you

toprepared sizinginformation theguideshowsyouhow it’sdone. Then, whennewmodelheatersare

Index

Foreword introducedor applicationsaredifferent,youwill havetheinformation necessarytoproceed on

yourown withconfidence.

You will learn how to evaluate water characteristics which could affect system life and

performance,developaprofileofsystem operationtoestablishdemandandrecoveryperiods,

size energy and storage requirements to meet system demands and, all told, create a

successful commercial water heating system.

I. Introduction to Commercial Water heating

Parameters

Awater heateris anappliance forsupplyinghotwaterforresidentialor commercialuse otherthan

spaceheating. Themaximum outletwater temperaturefor a waterheater is210°F (98.5°C).

Water heaters are sometimes called boilers and may be so labeled. This is because the gallon

capacityofthe tankand/or theenergy inputisabove alevel forwhich somecodesrequire ASME

(American Society of Mechanical Engineers) construction. Essentially the requirement applies

whenthe water-containingcapacityisinexcess of120 gallonsor theheat inputis above200,000

Btuh (58.6 kw). Caution, some local inspectors interpret the code to mean including 120 gallons

and 200,000 Btuh. The “boiler” requirement can cause cost escalation or system rejection if not

takenintoconsideration bythe systemdesigner. One waythat moreexpensive heatercostsare

oftenavoidedis bycombining several“smaller”heaters intoa systeminsteadof onelarge unit.

The term water heater and water heating system is used interchangeably in this technical guide.

The water heating system may consist of one or more water heaters installed individually at

points-of-use or manifolded together to form a central system. Some systems are comprised of

waterheater(s),withorwithout storage,hot waterstorage tanks,circulatingpump,relatedpiping

andcontrols.

12345678901

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

12345678901

3

What is Hot Water?

Hotwateris waterto which heatenergy hasbeenadded .. .asmoreheat isadded the waterbecomes

hotter. Thiswater temperatureguideshows typicalwater heatingsystem design temperatures.

In practice, the system designer will establish the temperature or temperatures of hot water needed

forthevarious activitiesthrough consultationwiththe useror theirrepresentative. Itis alsonecessary

forthesystem designertoknowthe coldestenteringwatertemperature inordertodetermine temperature

rise.

The major objective of this presentation is to promote the design of energy-efficient commercial water

heating systems through proper sizing, equipment recommendations and system selection. Properly

designedcommercial andindustrial waterheating systemsare essentialto thehealth andwell beingof

the community. Some activities would have to suspend operations or risk serious health and comfort

problems if they do not have the quantity of hot water at the temperature needed during the time it is

required.

QUANTITY

TEMPERATURE

TIME & SPACE

Therefore, the key to proper water

heating system design is to identify

the quantity, temperature and time

characteristics of the hot water

requirement. Also, space available

forequipment shouldbe noted.

But first, a knowledge of water and

its characteristics is necessary in

order to effectively design a water

heating system.

SYSTEM CONCEPTS

*The average temperature of the hot and cold water mixture applied to the body.

The hot water being normally obtained from the commercial water heating system at 140°F.

12345678901

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

12345678901

4

Evaluating Water

The coldest water inlet temperature experienced during the year should be the base from which

the maximum system temperature rise is established. Your water supplier can provide this

information. Surface water sources such as lakes and rivers tend to fluctuate as the seasons

change. Well water remains relatively constant in temperature year round. A water heating

systemsupplied withvarying incomingwater temperatureswill onlyprovide adequatehot waterif

thelowestcold watertemperature encounteredisused inthe temperaturerisecalculation.

Othercharacteristics ofthewater supplywhichshould bedeterminedand evaluatedbythesystem

designer include supply pressure, water hardness and the presence of silt. These facts may be

obtainedbycontactingyourwater supplier.

High water supply pressure (above the rated working pressure of the heater) should be reduced

bya waterpressurereducingvalvesettoabout 50psig. This willalso reducewater consumption

but, more important, will bring the water pressure well within the working pressure range of the

heater. It is then possible to provide proper relief valve protection on the heater.

It is also necessary to provide water pressure reducing valves on the 180°F rinse lines of

dishwashers.

Hardness is the term applied to the compounds of calcium and magnesium present in hard

water. So common are these two minerals in water that practically no supply can be found that

does not contain at least 1 or 2 grains per gallon. Hardness is also stated in parts per million.

One grain of hardness is equal to 17.1 parts per million. Water containing less than 1 grain per

gallon of dissolved calcium and magnesium hardness minerals is considered soft water.

The significance of hardness is that the heat transfer surfaces of the water heater will become

coated or blocked with the mineral deposits. Depending upon the type of heater, less hot water,

noisy operation, increased energy costs and premature equipment failure are some of the

problems which may result from “hard” water. The system designer should select water heating

equipment which is capable of being delimed or repaired when used in hard water areas.

If the water supply contains silt or sediment, the water heating equipment should be capable of

being flushed (and have sediment risers installed in horizontal storage tanks) to extend heater

life and minimize energy expense.

The effects of hard water and silt upon the heating equipment can be minimized by lowering

water temperature, controlling flow, leakage and waste. For example, fixture and shower head

flow controls are a must to minimize hot water consumption and regulate the flow to system

design.

Energy saving fixtures benefit the user by reducing water and sewerage charges, energy and

maintenance costs. Reducing consumption through flow control is the one way initial cost,

operatingcosts andthe space tobe occupiedbyanewwater heatingsystem canbe dramatically

reduced.

SUPPLY WATER

TEMPERATURE

PRESSURE

HARDNESS

12345678901

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

12345678901

5

Hot Water Demand

Themajordeterminationinsizingandthebasisofallcomputationsisestablishingthe probabledemand

for hot water. In addition, any unusual conditions which might relate to hot water consumption must

alsobe recognizedand plannedfor. UnusualconditionswillbedescribedunderProfilesofOperation.

Sources of hot water demand information include the ASHRAE (American Society of Heating,

Refrigerating and Air Conditioning Engineers) Guide, and hot water using equipment manufacturers

suchasdishwasher andwashing machinemakers. Government agenciesmayalso requiredemand

criteria be met.

Profiles of Operation

The system designer should draw a profile of the proposed system hot water usage demand period.

The profile will also include the recovery period available before the next demand. Demand and

recovery periods can be measured in seconds, minutes or hours.

Any unusual needs for hot water during the demand or recovery periods are identified in order to

provide additional tank and/or recovery capacity. An unusual need could be a lesser, but significant

hot water requirement appearing just after the demand period. For example, a motel could have a

laundry operation which begins in mid-morning, after the guest shower load is over. If not taken into

consideration there many be no hot water available for the washing machines.

Anoversimplificationofsystemdesignis tosaythat systemsareeitherforintermittentuseorcontinuous

use as shown in the following profiles.

.

This example shows two demand and recovery periods within a day.

• A combination of heater recovery and hot water storage capacity should be selected to handle the

demands.

• The demands are separated by an 8 and a 12 hour recovery period.

• The heater recovery capacity of the shortest recovery period must be sufficient to heat all the water

in storage.

• Short demands usually mean placing emphasis on tank size. Heater recovery capacity is emphasized

on longer demands.

• The dividing line between long and short demands is about 3 to 4 hours.

• In this example storage is most important.

-The purpose of the storage tank is to permit relatively low heater recovery capacity while still

maintaining adequate hot water supply during the demand period.

II. Principles of Sizing

Intermittent Use Profile

12345678901

6

• This example could represent an industrial process which is operated for two continuous shifts

a day.

• Hot water is used at a maximum rate of 3.3 gpm or 198 gph. (It is important to establish

maximum flow rate and water temperature rise in order to select a heater model.)

• In this example heater recovery is most important as the system for all practical purposes is an

instantaneous one. That is, it heats the water at the rate it is being used.

• If a tank type water heater is used, the tank size is minimum . . . just large enough to put the

heat into the water.

Recovery Capacity Tables

Recoverycapacity tablesare thepublished resultsoflaboratorytestswhichestablishthe abilityof

aheatertoraisethe temperatureof agiven volumeofwater acertain numberof degreeswithin a

giventime period.

Recovery tables are prepared for all State commercial water heaters regardless of the type fuel

used. In each instance the thermal efficiency of the particular type heater has been taken into

consideration.

The tables shown here are representative for the types of heaters produced by State using a

varietyoffuels. Inthispublication, forelectricity, recoveryat 1kWforvarioustemperaturerises is

shown. The table can then be used without regard to model number as all electric heaters are

considered100% thermalefficient.

III. Equipment Performance

Continuous Use Profile

Recovery Capacity

Calculated at

Thermal Efficiency of

@ 94%

@100%

Recovery Capacities Electric Tank Type

Kilowatts* Btu TemperatureRise-Degrees F - Gallons Per Hour

(kW)Produce 30 40 50 60 70 80 90 100 110 120 130 140

1.0 3,413 13.6 10.3 8.1 6.8 5.8 5.1 4.5 4.1 3.7 3.5 3.3 3.0

*1 KW = 1000 Watts

Recovery Capacities Gas Tank Type

Approx. Input Rating

Gal. Btu/Hour TemperatureRise-Degrees F - Gallons Per Hour

Model Cap. Nat. & Prop. 30 40 50 60 70 80 90 100 110 120 130 140

SUF

100-150 100 150,000 570 427 342 285 244 214 190 171 155 142 131 122

12345678901

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

12345678901

7

Whenused ataltitudesof2000’or moreabovesealevel,gas-fired heaterrecovery capacitiesmustbe

derated4% foreach 1000’abovesealevelinordertoreflectactualrecovery.

RecoveryCapacity meanshotwateratthe heaterrecoveryrate minuteafterminute,hourafter hour. If

the hot water demand period is more than 3 or 4 hours, recovery capacity usually becomes more

importantthanstorage capacity.

Heaterrecoverycapacity plususable storagecapacity mustbe sufficienttosupply theamount ofhot

waterconsumed duringthe peakdemand period.

CAUTION: Many tables refer only to gallons per hour recovery. Be certain that the heater will

alsomeetyour gallonsper minuterequirements.

Storage Capacity and Tank Efficiency

Theheatertankprovidesasourceofinstanthotwater,overandabovetheheaterrecoveryrate. However,

the supply of hot water in the tank cannot be replenished until the recovery capacity of the heater

exceeds the demand upon the system. This is usually after the peak hot water demand period has

ended.

Obviously the actual availability and temperature drop of any system will depend upon the hot water

demandflow rateand pipingconcept.

The potential for hot water temperature drop during the demand period must be kept in mind by the

systemdesignerwhen establishingthetanktemperature. For example,whilethehotwatertemperature

guide,page 3,lists showersat 105°F,the systemtemperature isactually setfor 140°F. Amixing valve

would limit hot water temperature supplied to person use fixtures to 120°F. In this way the ability to

handlea30°Fdropduring thedemand periodis builtinto adesign. The watertemperatureattheend

of the demand would still be above that required by the use . . . about 110°F. Were the system

temperaturedesigned to105°F, thetanksize wouldhave tobeabout halfagainaslargebecause there

Tanksizeisusuallymoreimportantthanrecoverycapacitywhenlargequantities

of hot water are required in a short period of time . . . less than

3 or 4 hours.

Allofthe storedhot waterisnot availablefrom thetankat thedesired system

temperature. Thisis becausehotwaterispushed fromthesystembyentering

coldwater, resultingin temperaturedilution ofthewater instorage.

The term usable storage is employed to indicate the quantity of water which

must be available from the tank before dilution reduces temperature to an

unusable level. Therefore, tank size should be increased by a percentage to

cover the expected loss of hot water temperature so enough usable water

will be available.

When a specific drop off characteristic for a system is unknown or tank efficiency is

not given, 70% availability within a 30° F temperature drop during the demand period

may be applied to the tank of a heater or system. For systems requiring precise

delivered temperatures, figure 60% availability from the tank.

wouldbe no“extra” heatinthewater

to “stretch” the tank contents. The

water temperature would also drop

below that required by the use. So

heating water above the needed

temperature in systems employing

tanks is common as it reduces tank

size through the added heat energy

availablein thestored water.

12345678901

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

12345678901

8

State commercial tank type water heaters, hot water storage tanks and water heating systems using

tanks have assigned tank efficiencies as follows:

Gas and Oil-Fired Tank Type Heaters

• Use70%tankdraw efficiencyfor allone andtwo temperatureapplications. Forexample,agas

firedUltra Force®SUF100-150modelhasan 100gallon tank:

• 100x.70 =70.0usable gallonsofhot wateravailablewithin 30°Ftemperaturedrop duringthe

demandperiod.

• Conversely, if 70.0 gallons of usable hot water were needed from the tank over the demand

period, the minimum purchased tank size would be:

70.0 ÷ .7 = 100 gallons

Note: Storing water below 140°F may require more storage capacity.

• If the input of the heater is satisfactory for recovery purposes but the tank size is not, an

auxiliaryhotwaterstoragetankmaybepipedinto thesystemto increasetheamountofavailable

hot water during the demand period. State instruction manuals show the details.

Electric Tank Type Heaters

•Use70%tankdrawefficiency forall twotemperature applications. Forexample, amodel CSB

- 52 has a 52 gallon tank: 52 x .70 = 36.4 usable gallons of hot water available

within30°F temperaturedrop duringthe demandperiod.

•Conversely,if36.4gallonsof usablehot waterwere

neededfrom thetank overthe demandperiod, the

minimum purchased tank size would be:

36.4 ÷ .7 = 52 gallons

•Use 80% tank draw efficiency for one temperature

systemsinthesamemanner asdescribedfor twotemperature.

•Asin theexample ofgas andoil-fired tanktypeheaters,

andauxiliarytankcanbeusedtosupplementtheheatercapacity

ifnecessary.However,itshouldbenotedthatStatecommercial

electric water heaters are available in tank sizes to 120

gallons. Booster size heaters may also be connected to

auxiliary tanks of any size. This would permit fuel conversion

at a later date by heater substitution.

.

Auxiliary Tank (Unfired)

•Asexplainedpreviously, auxiliarytanks areused toincreasethe hotwater storagepotential of

.

gas and oil-fired an electric tank type heaters. Also, auxiliary tanks are used with gas copper

heatexchangertypeheatersin applicationsrequiring storedhot water.

•Use70%tank drawefficiency forall twotemperatureapplications.

•Use 80% tank draw efficiency for all one temperature applications piped according to State

instructionmanuals.

Heater Recovery Plus Storage Tank Equals Demand

Aspreviously explained,select maximumrecovery andminimum storageif thehot waterdemand

period is longer than 3 or 4 hours. Storage must be sufficient to handle any peaks within the

demandperiod.

•

12345678901

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

12345678901

9

Eight hour demand period,

per hour capacity.

171gphrecovery Storage:

+ 8 gal storage

179gal/8 hour 100gallon tank

Recoveryprovides96% x 70% tank efficiency

ofdemand. = 70 usable gallonsover 8hours

70.0 _8 = 7.8 or 8 usable gallons per hour

Here’showit’s figured: 171gph recovery+ 8gallonsstorage perhour =

179gallonsofhotwateravailableperhourfor8hours.

Thereafter, until the tank is reheated, only the heater recovery of 171 gph is available. The

heaterrecoveryobviouslyprovidesthehot water inalong,continuousdemandperiod.Without

any use of hot water during the recovery period the tank contents should be reheated within

about 25 minutes (70.0 ÷ 171 = .41 hour).

Select minimum recovery and maximum storage if the hot water demand period is less than 3 or 4

hours. Heater recovery must be sufficient to reheat the entire tank contents before the next demand

period.

To summarize:

“Short”Demand: “Long”Demand

• Min. recovery • Max. recovery

• Max. storage • Min. storage

Checkfor thepossibilityofanyhot waterneedsoccurringduringthe recoveryperiod whichcould affect

thereheating ofthe system.Add heaterrecovery and/orstorage tankcapacity asnecessarytohandle

unusualconditions.

Equipmentsizing calculationsmay leadto acombination ofheater recoveryand storagetank whichis

not made. If so, both factors may be “adjusted” to favor one or the other as desired. Here’s how:

1. Whereit isimportantthathotwatertemperaturebemaintained(as opposedto “withina 30°Fdrop”

beingo.k.) increaserecoverycapacityinpreferencetoincreasingtanksize. Thiswillaidinmaintaining

systemtemperature.Also,assume10% lessdraw efficiencythan ifthe 30°Fdrop wasacceptable.

2. Whereit isimportant tomaintain watervolume (fordemands possiblyin excessof heaterrecovery)

increasetanksize inorder toprovide“instant” hotwater.

Heater Recovery and Storage Tank Performance Comparison

These examples demonstrate the roles that heater recovery and storage tank capacity play over a demand

period. For example, a Model SUF 100 -150 which has an 100 gallon tank, when used for a one or an eight

hour demand provides:

One hour demand period

171gphrecovery Storage:

+70galstorage 100gallontank

241gal/1 hour x 70% tank efficiency

Storageprovides 30%ofdemand = 70.0 usable gallons

Here’showit’s figured: 171gph recovery+ 70.0gallonsstorage =241

gallonsofhotwater availablefor onehour.

Thereafter,untilthe tankis reheated,only theheater recoveryof171 gphis available, The

heatertankobviously providesa goodportionof thehot waterin ashort,intermittent

demand period. Without any use of hot water during the recovery period the tank contents

should be reheated within about 25 minutes (20 ÷ 171 = .41)

12345678901

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

12345678901

10

When Using Electricity To Heat Water

Thesystemdesignermaywantto modifytheprecedingheaterrecoveryandstoragetankcapacity

informationwhenusing electricityto heatwater.

Thisis becauseelectricity forcommercialuse,includingwater heating,is oftensoldonademand

ratebasis. This means,in additionto theenergy charge(measured inkWh), thereis acharge for

thedemand(measured inkW) that acustomer imposesuponthe electricalservice. Yourpower

companywill provideand explainrate informationupon request.

kWh=ENERGYUSED

(HEATSWATER,COSTSPENNIES)

kW=DEMAND

(DOESN’THEATWATER,COSTSDOLLARS)

Thepresence ofademandratemeans thesystemdesigner shouldminimizerecovery(heaterkw

rating)and maximizestoragecapacity(heatertanksize.)Demand chargescan greatlyincrease

the cost of using electricity to heat water.

Anotherapproach tominimizeelectric demandisto provideenoughhot waterstoragetoallowthe

elements to be turned off during periods of peak electrical usage. This may be done with a

locally obtained time clock or through demand limiting equipment supplied by State or others in

the energy control business. Working with the customer, power company, heater supplier and

electriciancan oftenresultin significantpowercost savingsbyprovidingcontrolovertheelectrical

demand.

Estimating Water Heating Costs

Occasionally the system designer may want to project energy expense and make fuel cost

comparisons as a part of the system design project.

If so, use this formula and the example as a guide.

Cost = (Gallons per time period) x (8.25) x (temp. rise) x (cost of fuel per sale unit

(Btu content of fuel per sale unit) x (Heater efficiency)

Cost example of heating 50 gallons of water with electricity:

Cost = (50)x(8.25)x(100)x(.08) Notes:

(3413) x (1)

Cost = 2062.5 8.25 - Weight of gallon of water

3413 8.00¢ per kwh assumed

Cost = 96 cents based on 100% efficiency, plus 1 kW= 3413 Btu/h

demand and fuel adjustment charges

if applicable. Efficiency = 1 (100%)

12345678901

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

12345678901

11

IV. System Types and Application

Design Objective

Theobjectives inthedesign ofcommercialwater heatingsystemsare numerousandvaried. Themajor

considerations which the system designer should include in the planning stages are:

1. The heater and related system components and their installation must comply with all applicable

codesand requirements.

• ASMEconstructionand NSF(National SanitationFoundation) labellingaretwo examples

of requirements which may have to be met.

2. Waterheatingsystem performancemust promotethehealth, welfareand safetyofthe public.

• Oftentimesexact watertemperatures overa longperiod oftimeare requiredin orderto

provide sanitation. This quality must be built into the system in the design stages.

3. Efficiently utilize energy to achieve the least possible operating costs.

• Electricity is an example of a fuel which must be applied thoughtfully to avoid unnecessary

demandcharges.

4. Provide the quality and features needed to attain the desired results at least cost.

• Least cost means not only initial cost but operating costs as well. Often times higher initial

cost can be offset by lower operating costs achieved by using State energy-saving water

heatermodels.

System Types

Water heating systems may be divided into two basic types. The types depicted in State instruction

manuals are either one temperature or two temperature systems. Of course the customer, through

fixtureadjustment,may obtaina varietyof temperaturestoserve theirneeds.

• OneTemperature systemsproduce onlyone temperatureofhot waterto satisfythe demand.

• TwoTemperature systemsproduce twotemperatures ofhotwaterandareusuallyassociated

with foodservice functions. Thehigher temperaturewater isusedfor dishwashersanitizing

rinse. Two temperatures maybe producedbya singlewater heater witha mixingvalveor by

twowater heatersset attwo differenttemperatures.

Withineach divisionarenumerous systemnames whichshouldbe understoodandusedbythe system

designer. It is important to correctly identify a system so the plumber and electrician will follow the

properinstructions anddiagrams. The followingdescribes thesystem nomenclatureused byState as

it applies to the various types of heaters and fuels in use.

Tank Type Water Heater Systems Using Gas, Oil And Electricity.

One Temperature

1. OneTemperatureandBoosterarethenamesofonetemperaturewaterheatingsystem.

• OneTemperatureimpliesthatthe onetemperature hotwater producedin the

heaterisfor general purposeuse.

• Traditionally, aBooster system receiveshot water (usuallyat 140°F) and

raisesitto180°Fforuse inthedishwasherfinalrinse. TheBoosteris therefore

aonetemperature waterheating system. Thetank typeheateris theproper

choice for a Booster system serving a stationary rack type dishwasher

becauseoftheirintermittentuse of180°F finalrinse water. Acombination of

heater recovery and storage tank capacity is the rule for a stationary rack

typedishwasher.

• One-temperature

• Booster.

12345678901

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

12345678901

12

2. TwoTemperatureprovidestwotemperaturehotwaterservicebymeans ofawatermixing valve

or through a pre-heater/booster heater combination. In the first concept the heater storage

tank is maintained at the highest system temperature required (usually at 180°F) and the

mixingvalve externallyproduces the140°F hotwater requirement.

The 180°F water in the tank is therefore piped to the water mixing valve for tempering and also

sent directly to the dishwasher final rinse.

Thepre-heater/boosterheater combinationprovides twotemperaturesof hotwater withoutthe

useof amixing valve. Oneheateris operatedat 140°Ftoprovidegeneralpurpose hotwater and

providea sourceofpre-heatedwaterfor theboosterheater. Theboosterheater raisesthe140°F

waterto 180°Ffor thedishwasherfinalrinse.

CAUTION

STORINGWATERAT HIGHER THAN NECESSARYTEMPERATURESRESULTS IN MORE RAPID LIME

BUILD UP, MORE CORROSIVE WATER, AND INCREASES THE POSSIBILITY OF CAUSING INJURY

TOANYONECOMINGINTOCONTACTWITH THE HOT WATER.

Pre-heater/booster heater

Two-temperature (with mixing valve)

12345678901

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

12345678901

13

Creating the Successful System

Creatingthe successfulcommercialwaterheatingsystem isa jointventureinvolving manypersons

and skills.

In order to select the right system using either tank type or copper type heaters, one should

understand the role that each of the persons concerned with the installation plays.

Thefollowingchart summarizesthe responsibilitiesfor eachofthe roles.

Remember, your customer’s success or profit may depend upon the continued availability of hot

water . . . and you will achieve that goal through proper system selection and sizing.

IDENTITY RESPONSIBILITY

Customer Must definehisneeds

System designer* Designs a water heating system to satisfy

the customer’s needs. Acts as an interface

betweenall involvedparties.

Water HeaterSupplier Furnishes the equipment to meet the system

and/or specifications. May aid the designer in

Manufacturer equipmentselection orspecifications with

hisknowledge ofproductperformance

andavailability.

Plumbing and Electrical Mustunderstandsystem conceptto provide

Installation Contractors installation, startup and customer instruction.

Alsoprovide maintenanceandservicefor

continuedsatisfaction.

Energy Supplier Advises characteristicsof energyavailable

at job site and how to achieve best use.

Particularly important when electricity is

thefuel.

Water Supplier Advisescharacteristicsof water,lowest

temperature,maximum pressureand

hardness.Mayinfluenceheaterselection and

useof apressurereducingvalve.

*The system designer may be the architect, engineer, installing contractor or

water heater supplier.

Sizing Without Prepared Information

Thefollowing procedureswill establishheater recoveryand storagetank capacitiesfor intermittent

use systems.

Continuoususesystemsaresized sothat heaterrecovery equalsorexceedsdemand. Therefore

the size of the tank (when proposing a tank type heater system) is unimportant.

Theproceduresfor oneand twotemperaturesystems areessentially thesame:

1. Establish the hourly 1 / hot water demand in gallons and the maximum temperature rise.

12345678901

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

12345678901

14

2. Select a trial size heater 2 / .

3. Subtractthe hourlyheater recoveryfrom thedemand.

4. Thedifference ingallonsbetweendemandandrecoverymustcomefrom thetank.

5. Multiplythedifference bythe numberofdemand hours. Theresult isthe “usable”numberof

gallons which must come from the tank.

6. Divide the “usable” tank gallons by .7 or .8 to obtain minimum tank size needed, see pages

7 thru 10.

7. Compareminimum calculatedtanksizewiththat ofthe “trialsize” heater. If theheater tankis

equal to or greater than calculated tank size the selection is satisfactory. If not, adjust

recoveryandstorage asnecessary, seepage 10.

8. Divide the heater tank size by the heater recovery to be certain the tank will be recovered by

the time of the next demand. If not, adjust recovery and storage as necessary, see page 10.

1* / The demand could be in minutes or seconds. In either case all references to hours in the

procedurewouldreverttominutes orseconds. For example,a stationaryracktypedishwasher

mayhave a12seconddemandperiodandan83second recoveryperiod.

2* / Review PROFILES OF OPERATION, Page 5, as an aid in determining whether to favor

recovery or tank capacity in the selection of a “trial size” heater. Normally the hourly heater

recoveryoftheheaterselected shouldnot exceedthe hourlydemand. In thiswaythe hotwater

content of the tank will be put to use.

One temperature example

1. Atwohour demandof 206gphof 140°Fwater hasbeen established. Thelowestincoming

watertemperature is40°F. Theshortest timein anyday inwhich thedemandwillberepeated

is 8 hours.

2. A State gas-fired tank type commercial water heater will be selected for the job. (Any fuel or

type of heater could be substituted in this example.)

“Try” a Model SUF 100 -150. This heater has 171 gallons per hour recovery at 100°F water

temperature rise and an 100 gallon tank.

3. Needed: 206 gph for 2 hours

Subtract: -171gphheaterrecovery at100°F rise

Equals: 35 gallons needed from tank, first hour

Multiplied by: x 2 demand hours

Equals: 70 usable gallons needed from tank

Divide: 70 ÷ .7 = 100. gallons minimum tank size

Capacity 100gallontank vs.100.gallon tankminimum

Comparetank sizevs.recovery:

Used 70 gallon. 8 hours is available to recover tank.

(70-171gphrecovery=.41,.41X60minutes=24.6minutesneededtorecover

70gallons.

Conclusion:The ModelSUF100-150willdothe joband shouldbe theheater selected.

CAUTION: A twohourdemand of206gph meansthatthe 206gphisspreadthroughoutthe

entire hour. It does not mean that 206 gallons is dumped in 15 minutes and no additional hot is

used in the remaining 45 minutes.

12345678901

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

12345678901

15

Two temperature example

1. A one hour demand of 75 gallons of 180°F water and 110 gallons of 140°F water has been

established. The lowest incoming water temperature is 40°F. The shortest time in any day in which

the demand will be repeated is 3 hours.

2. Convert the 180° water requirement into the equivalent of a 140°F water requirement to avoid working

with two different temperature rises.

Converting to a single temperature rise:

• Multiply the 180°F requirement by 1.4 in 100°F temperature rise applications.

a) This means 1.4 more water can be raised from 40°F to 140°F than 40°F to 180°F with the

same amount of energy.

b) Multiplier formula:

Hot - Cold

——————— = multiplier

Mixed - Cold

Example:

180 - 40 140

————— = ——— = 1.4

140 - 40 100

c) 75 gallons 180°F water required

x 1.4

105equivalent gallonsof 140°Fwater

•Addthe converted180°F waterrequirement tothe 140°Frequirement andproceed withheater

selection.

a) 105 +110gallons of140°F water= 215equivalent gallonsofhotwaterrequired

at100°F watertemperaturerise.

3. A State electric tank type commercial water heater will be selected for the job. (Any fuel or type of

heater could be substituted in this example.

ReviewSYSTEM TYPESANDAPPLICATIONbeginningonpage11.

“Try” a CSB -120 with 24 kw input. This heater has 98 gallons per hour recovery at 100°F water

temperature rise and a 119 gallon tank. The heater will be operated at 180°F and equipped with a water

mixing valve set at 140°F.

4. Needed: 215 gallons for one hour

Subtract: -98 gph heater recovery at 100°F rise

Equals 117 usable gallons needed from tank

Compare

tank 119 gallon tank vs. 117 gallon tank minimum

capacity:

NOTE: The 119 gallon tank capacity at 70% tank efficiency is equal to 83 gallons of usable hotw a t e r .

However, it is 83 gallons of 180°F water and therefore has the heat content equivalent of

83 x 1.4 = 116 gallons of 140°F water. Therefore the tank size is adequate (only 1 gallon short).

Compare tank size 1.21 hours vs 3 hours available.

vsrecovery: (119 ÷ 98 = 1.21 hour)

Conclusion: The model CSB -120 with 24 kw input will do the job and should be the heater selected.

Field Assistance

Please contact your local State distributor, sales representative or the technical information center (See:

www.statewaterheaters.com for phone and fax numbers) if you need help designing a water heating system or selecting

the proper equipment for the job.

12345678901

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

234567890

1

12345678901

16

STATEWATERHEATERS

ASHLANDCITY,TENN.

TECHNICALINFORMATION

800-365-0577

State Water Heaters 317913-000 Quick start guide

Popular Water Heater manuals by other brands