heat-timer EPU-D User manual

059840‐00Rev.A
Installation and Operation Manual
EPU-D
Light Commercial Steam Cycling Control
WARNING
This Heat-Timer control is strictly an operating control; it should never be used as a primary limit or safety
control. All equipment must have its own certified limit and safety controls required by local codes. The installer
must verify proper operation and correct any safety problems prior to the installation of this Heat-Timer control.

TableofContents
059840‐00Rev.AHeat‐TimerCorp.
2
Controls,Indicators,andConnections ............ 3
DetailedOperation............................4
Overview..................................4
The“Cycle”Concept ........................4
CycleLengthBasedonOutdoorTemperature .4
CycleLength ............................5
AvailableHeatLevels ..................... 7
SequenceofOperation...................... 7
TypicalConfigurations ....................... 8
EPU‐DInputs...............................8
HeatingSystemSensor ....................8
PressuretrolSensor.......................8
OutdoorTemperatureSensor..............8
RemoteShutdown/TSTATEnable..........9
EPU‐DOutputs .............................9
ValveActuator...........................9
BoilerBurner ............................9
Specifications ...............................10
EPU‐DControlModule .....................10
InstallationInstructions.......................11
SuppliedMaterials .........................11
RequiredMaterials(NotSupplied) ............11
DesignConsiderations ......................11
OutdoorTemperatureSensorInstallation...12
HeatingSystemSensorInstallation .........13
MountingtheEPU‐DModule................14
MountingtheEnclosure ..................14
MountingtheDisplayModule .............15
WiringtheEPU‐D ..........................16
PowerInputWiring......................16
OutputWiring..........................16
InputWiring............................18
Powering‐OntheEPU‐D ..................19
CompletingtheInstallation...............19
InitialProgrammingoftheEPU‐D.............20
SystemStartupMenu ....................20
EPU‐DDisplayandProgramming...............23
EPU‐DControlModuleStatusLEDs ...........23
DisplayandVariable‐FunctionButtons ........23
DefaultDisplay .........................24
DisplayIconsandMessages...............24
SettingtheDisplayContrast...............25
ResettingtoFactoryDefault .................25
EPU‐DMenus ............................ 26
MainMenu............................ 26
SystemSettingsMenu................... 29
SchedulesMenu........................ 33
MaintenanceMenu ..................... 35
PipingDiagrams............................. 38
Troubleshooting ............................ 41

Controls,Indicators,andConnections3
059840‐00Rev.AHeat‐TimerCorp.
Controls,Indicators,andConnections
Figure1: EPU‐DControls,Indicators,andConnections
Item Description Item Description
1 StatusLEDs
See“EPU‐DControlModuleStatusLEDs”on
page 23.
5 Prgm/RunSwitch
PlacestheEPU‐Dinprogrammingmodeorrun
(normaloperation)mode.
NOTE:Programmingmodemaybepassword
protected.
2 DigitalDisplay
See“DisplayandVariable‐FunctionButtons”on
page 23.
6 OutputConnections
• Terminals4&5–notused
• Terminals6,7,&8–OutputtoBoiler
BurneroraMotorizedValve
3 Variable‐FunctionButtons
See“DisplayandVariable‐FunctionButtons”on
page 23.
7 120VacPowerInputConnection
• Terminal1–InputLineVoltage
• Terminal2–Neutral
• Terminal3–Ground
4 InputConnections
• Terminals9&10–HeatingSystemSensor
• Terminals11&12–OutdoorTemperature
Sensor
• Terminals13,14,15,&16–notused
• Terminals17&18–RemoteShutdown
12
3
7 456

4EPU‐DInstallationandOperationManual
059840‐00Rev.A Heat‐TimerCorp.
DetailedOperation
Overview
TheEPU‐Disamicroprocessor‐basedcontroldesignedtomanagealow‐pressuresteamheatingsystem.The
controlcanoperateasteamboileroratwo‐waysteamvalveusinga“cycle”concepttoprovidethedesired
amountofheattothebuilding.
The“Cycle”Concept
The“cycle”conceptwascreatedbyHeat‐Timerspecificallytoallowsteamheatingsystemstoovercomethe
inabilitiesofstandardthermostaticcontrolstocopewiththeuniquechallengesoflow‐pressuresteamheating.
Unlikewaterandairsystems,steamsystemstaketimetobuildupa“headofsteam”.Moreover,afterthe
systemstartsheatingup,ithasmomentumthattakestimetodissipate.Thismakesitdifficulttocontrolits
temperature.
CycleLengthBasedonOutdoorTemperature
Bymonitoringtheoutdoortemperature,theEPU‐Disabletoanticipatethebuildingheatingneeds.Eachcycle
period(usually60minuteslong,butadjustabledependingonthetypeofradiationunits)consistsofaCycle‐ON
segmentandaCycle‐OFFsegment.ThelengthoftheCycle‐ONsegmentwillvarywiththeoutdoor
temperature.Thecolderitisoutdoor,thelongertheCycle‐ONsegment.
Figure2: Example60MinuteCycle
TheEPU‐Dconstantlycheckstheoutdoortemperaturebymeansofasolid‐statesensorlocatedontheexterior
ofthebuilding.Atthesametime,itmonitorstheheatingsystemofthebuildingbymeansofeitheraheating
systemsensororreverse‐actingpressuretrol.Thesesensorstellthecontrolwhensteamhasreachedthe
furthestlocationinthebuilding(orthehardesttoheatarea,see“PipingDiagrams”onpage 38).Basedonthis
combineddata,theEPU‐Dsendsinstructionstotheheatingplanttocontroltheheatlevelinthebuilding.
TheEPU‐Dalsoprovidestwoadjustableoutdoortemperaturecutoffsettings,onefordaytimeoperationand
onefornighttimeoperation.Whentheoutdoortemperaturerisesaboveoneofthecutoffsettings,theEPU‐D
willnotcallforanyheat.

DetailedOperation5
059840‐00Rev.AHeat‐TimerCorp.
Whentheoutdoortemperaturedropsbelowthecutoff,theEPU‐Dwillautomaticallybegincontrollingthe
heatingcycle.Aftertheheatingsystemisactive,theheatingsystemsensorwillregisterwhenheathasreached
throughoutthebuilding.Thecombinedeffectofthesetwosensorsistoprovideaneven,comfortablelevelof
heatthroughoutthebuilding.
Figure3: ExampleCyclesBasedonWeatherConditions
CycleLength
ThedurationoftheCycle‐ONperiod(whentheheatsourceisactivated)dependsonfourfactors:
• Outdoortemperature
• OutdoorCutofftemperature
• HeatAdjustmentsetting
•Cyclelength
WhentheoutdoortemperatureisabovetheOutdoorCutoff,theEPU‐Dwillnotcallforheat.Whentheoutdoor
temperatureisbelowtheOutdoorCutoff,thelengthoftheCycle‐ONsegmentisadjustedbythedayandnight
HeatAdjustmentsettings.“A”istheshortestheatduration,“P”isthelongestduration.

6EPU‐DInstallationandOperationManual
059840‐00Rev.A Heat‐TimerCorp.
Table1:CycleLengthTable
*HeatAdjustmentSetting–See“DayAdjustment”onpage 30and“NightAdjustment”onpage 30.
Example
Todeterminethecyclelength,usetheexamplevaluesbelow:
• Outdoortemperature=30°F
• OutdoorCutoff=55°F
• HeatAdjustment=G
1. SubtracttheoutdoortemperaturefromtheOutdoorCutoff(55–30=25°F)
2. RefertoTable 1wheretheHeatAdjustmentrow“G”intersectswiththe25°Fcolumn.TheCycle‐ONtimeis
14minutes(fora60minutecycle).
NOTE:Fordifferentcyclelengths,refertothetablebelow:
OutdoorCutoffMinusOutdoorTemperature(AllTemperaturesin°F)
*95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 1
A45 41 37 33 29 25 22 18 15 13 10 8 5 3 200000
B57 51 46 41 37 33 28 25 21 18 15 12 9 7 531000
CC 595448433833292521181512 9 753100
DC C C 5549433834292521171411 964210
EC C C C 55 49 43 38 33 28 24 20 17 13 1086421
FCCCCC5549433732272319151297532
GCCCCCC54 48 42 36 31 26 22 18 14 11 8 6 4 3
HCCCCCCC5347403529252016 13 10 7 5 4
ICCCCCCC5952453933272318 15 11 9 6 5
JCCCCCCCC58504337312521 16 13 10 7 6
KCCCCCCCCC564841342823 19 15 11 8 7
LCCCCCCCCCC5345383226 21 16 13 9 7
MCCCCCCCCCC5951433529 23 18 14 11 8
NCCCCCCCCCCC56473932 26 20 16 12 9
OCCCCCCCCCCCC534436 29 23 17 13 10
PCCCCCCCCCCCC594940 32 25 19 15 12
MinutesON(Basedon60MinuteCycleLength)
C=ContinuousOperation
CycleLength Divideby Cycle‐ON
20 3 5
30 2 7
90 2/3 21

DetailedOperation7
059840‐00Rev.AHeat‐TimerCorp.
AvailableHeatLevels
TheEPU‐Disabletomaintaintwodifferentheatlevels:
• Dayheatlevelprovidescomfortabletemperatureswhenthebuildingtenantsareactiveduringtheday.
Thisrequiresahigherlevelofheat.
• Nightheatlevelprovideslowerheatandconservesenergywhenthebuildingisemptyorwhentenantsare
asleep.Bothheatlevelsrelyontheidenticalcycleconcept,butthelowerNightsettingsprovidelessheat
giventhesameoutdoortemperature.
SequenceofOperation
ThissectiondescribesthetypicalsequenceofoperationfortheEPU‐D.
1. TheEPU‐Dactivatesthesteamsourcewhentheoutdoortemperaturefallsbelowtheoutdoorsensor
cutoff.Thecutoffisfactorysetat55°F(13°C)forDayorNight,butisfullyadjustable.
2. TheEPU‐Dcontinuestocallforheat,keepingthesteamsourceactive,untiltheheatingsystemsensor
reachesitsadjustableSetPoint.Thisindicatesthatsteamhasgottenentirelythroughthesystem,orthat
"heatisestablished".
3. After"heatisestablished",theCycle‐ONsegmentofthecyclebegins.
4. DuringtheCycle‐ONsegment,theEPU‐Dkeepsthesteamsourceactivated.ThelengthoftheCycle‐ON
segmentisdependentontheoutdoortemperature,theDay/Nightsetting,andseveraluser‐selectable
adjustmentsthatcanbetunedtothespecificheatlosscharacteristicsofthebuilding.
5. AftertheCycle‐ONsegmenthasended,theCycle‐OFFsegmentofthecyclebegins.TheEPU‐Dturnsoff
theboilerorclosesthesteamvalvefortheremainderofthissegment.
6. AftertheCycle‐OFFsegmenthasended,theEPU‐Donceagainactivatesthesteamsourceunlesseither
theoutdoortemperaturehasrisenabovethecutofforthethermallockoutisactive.
Withthethermallockout,theheatingsystemsensortemperaturemustfallbelowtheSetPointminusa
25°Fdifferentialbeforetheheatingsourcecanbereactivated.Thisallowsresidualheatinthepipesto
continuetoheatthebuilding.Afterthepipeshavecooledsufficiently,anewcyclecanbegin.

8EPU‐DInstallationandOperationManual
059840‐00Rev.A Heat‐TimerCorp.
TypicalConfigurations
TheEPU‐Dworkswithvirtuallyanynon‐vacuumoneortwo‐pipesteam‐heatedsystem.TheEPU‐Dcancontrol
theboilerdirectlytocreatesteamor,forsystemswhereacentralplantprovidessteam,theEPU‐Dcontrolsa
motorizedvalvetoalloworpreventsteamfromenteringtheheatingsystem.
Baseduponthespecificlayoutofthesteamheatingsystem,thereareseveraldifferencesinlocatingtheheating
systemsensorandintheoutputwiringtotheboilerormotorizedvalvethatmustbeconsidered.Itisimportant
tocarefullycheckthepipingdiagramtodeterminewhichofthefollowinglayoutsmatchesyourheatingsystem:
• OnePipeSteam‐DirectBurnerOperation(seeFigure 7onpage 38)
• Two‐PipeSteam‐DirectBurnerOperation(seeFigure 8onpage 39)
• Two‐PipeSteam‐MotorizedValveOperation(seeFigure 9onpage40)
EPU‐DInputs
HeatingSystemSensor
TheEPU‐DisdesignedtoconnecttotheprovidedHeat‐Timerheatingsystemsensor(p/n904220‐00).
Theheatingsystemsensorislocatedwhereitwillshowthatheathasreachedthefurthestlocationinthe
building.TheEPU‐Dusesthetemperatureinformationfromtheheatingsystemsensorcombinedwiththe
outdoortemperaturesensortocontroltheheatlevelinthebuilding.
PressuretrolSensor
TheEPU‐Dcanoptionallyconnecttoapressuretrolsensorinsteadofthesystemtemperaturesensor.
Thepressuretrolsensormustbeareverse‐actingpressuretrolthatindicateswhentostarttheheatingcycle
basedonaspecifiedpressuresetting.
OutdoorTemperatureSensor
TheEPU‐DisdesignedtoconnecttotheprovidedHeat‐Timertemperaturesensor(p/n904220‐00).
Theoutdoortemperaturesensorisasolid‐statesensorlocatedontheexteriorofthebuilding.TheEPU‐Duses
thetemperatureinformationfromtheoutdoortemperaturesensorcombinedwiththesystemtemperature
sensortocontroltheheatlevelinthebuilding.

DetailedOperation9
059840‐00Rev.AHeat‐TimerCorp.
RemoteShutdown/TSTATEnable
Theremoteshutdown/TSTATenablefeaturesetsthesignal(openorshort)ontheEPU‐DShutdownterminals
(17and18)thatallowsthecontroltooperate.
• ForShutdown,an“open”signalallowsthecontroltooperateandprovideheat.Whenshorted,thecontrol
isdisabled.
• ForTSTATEnable,a“short”signalallowsthecontroltooperateandprovideheat.Whenopen,thecontrol
isdisabled.
Whenthecontrolisdisabled,theBurnerandMotorizedValveoutputrelaysarede‐energized,turningoffthe
boilerorclosingthemotorizedvalve.
ThisfeaturecanbeusedwhenitisdesirabletodeactivatetheEPU‐Dfromaremotelocationorwithanother
controller,suchasaBuildingManagementSystem(BMS).
EPU‐DOutputs
ValveActuator
TheEPU‐Disdesignedtoconnecttoamotorizedvalveactuator.Usingtheinputsfromtheoutdoortemperature
sensorandthesystemtemperaturesensor,theEPU‐Dcontrolstheheatingsystembyopeningandclosingthe
motorizedvalveactuator.
BoilerBurner
TheEPU‐Disdesignedtoconnecttotheboilerburner.Usingtheinputsfromtheoutdoortemperaturesensor
andthesystemtemperaturesensor,theEPU‐Dcontrolstheheatingsystembyturningtheboilerburneronor
off.
CAUTION
TheShutdownsignalmustbedry‐contactonly.DONOTplacevoltage
acrosstheShutdownterminals.

10EPU‐DInstallationandOperationManual
059840‐00Rev.A Heat‐TimerCorp.
Specifications
EPU‐DControlModule
VoltageInput:.......................................................................120Vac60Hz
MaximumInputRating:.................................................................48VAmax
Dimensions(WxHxD): .............................. 11”x9”x3¾”(279.4mmx228.6mmx95.25mm)
Weight: ..........................................................................2.5lbs(1.13kg)
OutputRelays: ...................................................................1BurnerOutput
1ValveOutput
OutputRelayRating: ......................................BurnerOutput:1Apilotdutyat120Vac60Hz
ValveOutput:6Aresistiveat120Vac60Hz
Inputs:......................................................................SystemTemperature
OutdoorTemperature
RemoteShutdown
UserInterface:..................................................................... DigitalDisplay
DisplayUnits:Temperature(°Fand°C)
StatusIndicators(3LEDs)
Variable‐FunctionButtons(4)

InstallationInstructions11
059840‐00Rev.AHeat‐TimerCorp.
InstallationInstructions
TheEPU‐Dinstallationprocessconsistsofthefollowingbasicsteps:
1. Initialinstallation(see“DesignConsiderations”onpage 11).
• Locatingandinstallingthesensors.
2. MountingtheEPU‐DModule(seepage 14).
3. ConnectingtheEPU‐Dwiring(see“WiringtheEPU‐D”onpage 16).
• Powerwiring
• Outputwiring
• Inputwiring
4. CompletinginitialprogrammingoftheEPU‐D(seepage 20).
SuppliedMaterials
Thefollowingmaterialsaresuppliedwiththecontrolmodule:
• EPU‐DControlModule(p/n926840‐00)
• TwoSensorswithEnclosures(p/n904220‐00)
• WallAnchorsandScrews
• InstallationandOperationManual(p/n059840‐00)
• WarrantyCard(p/n059115‐00)
RequiredMaterials(NotSupplied)
Thefollowingmaterials/toolsarerequiredforinstallation,butarenotsupplied:
• Generaltoolkit(screwdrivers,wirestrippers,powerdrill,etc.)
• 18AWGcable(Heat‐Timerp/n703001‐01orequivalent#18/2cable)–usedforEPU‐Dwiring
DesignConsiderations
Wheninstallingthesystem,certaindesignconsiderationsmustbetakenintoaccount.Theseinclude:
• OutdoorTemperatureSensorLocations
• HeatingSystemSensorLocation
• OutputControl:BurnerorMotorizedValve

12EPU‐DInstallationandOperationManual
059840‐00Rev.A Heat‐TimerCorp.
OutdoorTemperatureSensorInstallation
Considerthefollowingwheninstallingtheoutdoortemperaturesensor:
• Onlyusethesensorprovidedwiththecontrol.
• Locatethesensorintheshadeonthenorthsideofthe
building.Thesensorshouldneverbeindirectsunlight.
• Besurethelocationisawayfromdoors,windows,exhaust
fans,vents,orotherpossibleheatorcoldsources.
• Thesensorshouldbemountedapproximately10feet
(3 meters)abovegroundlevel.
• Adheretheprovidedoutdoorlabeltothebackofthesensor
base.
• Usetheenclosurebasebottomknockoutfortheconduit.Use
thelocknuttoholdtheconduitandenclosurebasetogether.
Screwthecovertothebase.
• Makesuretosealaroundthesensorenclosureandwall,
exceptfromthebottomoftheenclosure.
• Thesensorwirescanbeextendedupto500feet(152.4
meters)usingshielded2‐conductor(#18/2)cable(HeatTimer
p/n703001‐01).
• Donotconnecttheshieldatthesensor.However,connecttheshieldatthecontrol.See“Wiringthe
OutdoorTemperatureSensor”onpage 19.
CAUTION
Determiningtheproperlocationfortheoutdoorsensorisveryimportant.TheEPU‐Dbasesthe
heatontheoutdoortemperatureinformationitreceivesfromthislocation.Ifthesensorisin
thesunorcoveredwithice,itsreadingwilldifferfromtheactualoutdoortemperature.

InstallationInstructions13
059840‐00Rev.AHeat‐TimerCorp.
HeatingSystemSensorInstallation
Considerthefollowingwheninstallingtheheatingsystemsensor:
• Onlyusethesensorprovidedwiththecontrol.
• Theideallocationfortheheatingsystemsensor
isonthefurthestradiatorinthesystem.This
radiatorisusuallythehardesttoheat.
• Thesensormaybelocatedonthefurthest
returnriser.However,thesensorMUSTbeabove
theboilerwaterline(onadryreturn).See
“PipingDiagrams”onpage 38.
• Straptheheatingsystemsensortothepipe
usingthetie‐wrapsprovidedwiththesensor.
Thenwrapinsulationaroundthesensorand
pipetoachievethehighestaccuracy.
• Thesensorwirescanbeextendedupto500feet(152.4meters)usingshielded2‐conductor(#18/2)cable
(HeatTimerp/n703001‐01).
• Donotconnecttheshieldatthesensor.However,connecttheshieldatthecontrol.See“Wiringthe
HeatingSystemSensor”onpage 18.
CAUTION
Determiningtheproperlocationfortheheatingsystemsensorisveryimportant.Iftheheating
systemsensorcannotsensethesystemisfullofsteam,theEPU‐Dwillnotprovidecomfortable
heatlevels.Besuretheheatingsystemsensorislocatedonaproperlyventedpipethatcannot
easilybeisolatedfromthesystem.
NEVERinstalltheheatingsystemsensorbetweenthecondensatereceiverandtheboiler.

14EPU‐DInstallationandOperationManual
059840‐00Rev.A Heat‐TimerCorp.
MountingtheEPU‐DModule
MountingtheEnclosure
1. SelectanappropriatelocationtomounttheEPU‐D.Thelocationmustmeetthefollowingminimum
requirements:
• Themountingsurfaceshouldbeflatandstrongenoughtoholdtheweightofthedevice.
• Thedevicecanbemountedamaximumof500feet(152.4meters)fromthesensorlocation,butshould
bemountedasnearaspossibletoavoidexcessivewireruns.
• DONOTmountthedeviceinalocationwhereitwillbeexposedtoextremeheat,cold,humidity,or
moisture.
2. RemovetheEnclosureWiringCover(1)byremovingthetwolowerscrews(2)holdingittothebase(3),
andthenremovetheDisplayModule(4)byremovingthetwomiddlescrews(5)holdingittothebase.
Figure4: EPU‐DControlModulePartsDiagram
1
2
3
4
5
5

InstallationInstructions15
059840‐00Rev.AHeat‐TimerCorp.
3. PositiontheEnclosurebaseinthedesiredlocation,andthensecurethebaseinplaceusingfourscrews
(provided)throughthemountingholes(1)onthebackoftheEnclosurebase.
Figure5: EPU‐DEnclosureBase
MountingtheDisplayModule
1. TurntheEPU‐Ddisplaymodule(1)overtorevealthebattery(2).Removetheplastictabtoactivatethe
battery.
Figure6: EPU‐DDisplayModuleBatteryLocation
NOTE:Thebatteryisacoinlithiumbattery(CR2032‐HeatTimerp/n020002‐00)thatisusedtomaintain
thecontrol’sdateandtimeduringpoweroutages.Thebatterycanmaintaintheclockforuptoatotalof
100days.
2. PositiontheDisplayModuleintothebaseandsecureitinplaceusingthemiddlescrewsremovedinStep 2
above.
NOTE:DonotreplacetheEnclosureWiringCoveruntilallwiringiscompleted.
3. Continuewith“WiringtheEPU‐D”onpage 16.
CAUTION
Donotactivatethebatteryunlessyouplantokeepthecontrolcontinuously
powered.Ifthecontrolhasnopower,thebatterywillloseitschargein100days.
1
1
1
2

16EPU‐DInstallationandOperationManual
059840‐00Rev.A Heat‐TimerCorp.
WiringtheEPU‐D
PowerInputWiring
1. De‐energizethecircuitthatwillprovidepowertotheEPU‐Dbyturningofftheappropriatecircuitbreaker.
2. Runthe120Vacpowerwiringthroughoneoftheknockoutslocatedonthe
bottomoftheEPU‐Denclosure.
3. Connectthehotlinetoterminal1ontheEPU‐D.
4. Connecttheneutrallinetoterminal2ontheEPU‐D.
5. Connectterminal3ontheEPU‐Dtoearthground.DONOTusetheneutralline
astheearthground!
OutputWiring
NOTE:TheEPU‐Doutputsdonotsourcepower.Ifpowerisneededataspecificoutput,aseparatepower
sourcemustbewiredinserieswiththeoutput.Eachoutputrelaycanswitcha6Aresistiveloadat120Vacor
a1Ainductiveload.
WARNING
ELECTRICALSHOCKHAZARD!Disconnectelectricalpowertothedevicebeforeservicingormaking
anyelectricalconnections.Failuretodosomayresultinseverepersonalinjuryordeath.
Useaseparatecircuitbreakerforthecontrol.Donotsharethecontrolpowerwithothermajor
equipment,pumps,ormotors.Heat‐Timerrecommendstheinstallationofasurgesuppressoranda
powerswitchbeforethepowerlineconnection.
Followalllocalandstateelectricalcodeswheninstallingthisunit.Allwiringmustmeetorexceed
local,state,orfederalcodesandrequirements.
CAUTION
TheinputpowerwiresmustbeN.E.C.Class1.Class1voltagewiringmust
useadifferentenclosureknockoutandconduitthananysensorwiring.
WARNING
ELECTRICALSHOCKHAZARD!Toavoidtheriskofelectricshock,DONOT
re‐connectelectricalpoweruntilALLwiringtotheEPU‐Discompleted.
Failuretodosomayresultinseverepersonalinjuryordeath.
CAUTION
Class2voltagewiring(low‐voltagesensorwires)mustuseadifferentenclosureknockout
andconduitthananyClass1voltagewiring.

InstallationInstructions17
059840‐00Rev.AHeat‐TimerCorp.
WiringtoaMotorizedValve
NOTE:TheEPU‐Ddoesnotsourcepowertothemotorizedvalve
terminals.Anexternal24Vdcpowersourceisrequiredandmustbe
connectedinseries,asshowninthediagram.
1. Runthemotorizedvalvesignalwiringthroughaknockoutlocatedon
thebottomoftheEPU‐Denclosure.
2. ConnectthemotorizedvalveCloseterminaltoterminal6onthe
EPU‐D.
3. ConnectthemotorizedvalveOpenterminaltoterminal8onthe
EPU‐D.
4. Connecta24Vactransformerpowersource.
a. Runatransformerwirethroughaknockoutlocatedonthebottom
oftheEPU‐Denclosureandconnectterminal7ontheEPU‐Dtoa
transformer24Vacterminal.
b. ConnectthemotorizedvalveCommonterminaltoatransformer24Vacterminal.
WiringtoaBoiler
NOTE:TheEPU‐Ddoesnotsourcepowertotheboilerterminals.Wiretheburner
outputinserieswiththeboilerlimitcircuit.
1. Runtheburnerenablesignalwiresthroughaknockoutlocatedonthebottomof
theEPU‐Denclosure.
2. Connectaburnerenableterminalstoterminals7and8ontheEPU‐D.

18EPU‐DInstallationandOperationManual
059840‐00Rev.A Heat‐TimerCorp.
InputWiring
WiringtheHeatingSystemSensor
NOTES:
• UseonlytheprovidedHeat‐Timerheatingsystemsensor(p/n904220‐00).Seepage 8fora
descriptionofthesensor.
• Foracceptablesensorlocations,see“PipingDiagrams”onpage 38.
1. RuntheSystemTemperatureSensorwiresthroughaknockoutlocatedonthebottomof
theEPU‐Denclosure.
NOTE:Thesensorwirescanbeextendedupto500feet(152.5meters)usingan18AWG
shielded2‐conductorcable(Heat‐Timerp/n703001‐01orequivalent#18/2cable).
2. ConnecttheSystemTemperatureSensorwirestoterminals9and10ontheEPU‐D.
3. Connecttheshieldtoterminal10ontheEPU‐D.
NOTE:Donotconnecttheshieldatthesensorend.
WiringanOptionalPressuretrolSensor
NOTES:
• Heat‐TimerdoesnotprovideaPressuretrolsensor.
• TheoptionalPressuretrolsensormustbeareverse‐actingsensor.Seepage 8foradescriptionof
thesensor.
• Foracceptablesensorlocations,see“PipingDiagrams”onpage 38.
1. ConnectwirestothePressuretrolnormally‐closedterminals.
2. RunthewiresfromthePressuretrolthroughaknockoutlocatedonthebottomoftheEPU‐D
enclosure.
NOTE:Thesensorwirescanbeextendedupto500feet(152.5meters)usingan18AWGshielded
2‐conductorcable(Heat‐Timerp/n703001‐01orequivalent#18/2cable).
3. ConnectthePressuretrolwirestoterminals9and10ontheEPU‐D.
4. Connecttheshieldtoterminal10ontheEPU‐D.
NOTE:Donotconnecttheshieldatthesensorend.
CAUTION
ToavoiddamagetotheEPU‐D,NOVOLTAGEcanbeappliedtotheEPU‐Dinput
terminals.
Class2voltagewiring(low‐voltagesensorandcommunicationwires)mustuse
adifferentenclosureknockoutandconduitthananyClass1voltagewiring.

InstallationInstructions19
059840‐00Rev.AHeat‐TimerCorp.
WiringtheOutdoorTemperatureSensor
NOTES:
• UseonlytheprovidedHeat‐Timertemperaturesensor(p/n904220‐00).
• Foracceptablesensorlocations,see“OutdoorTemperatureSensor”onpage 8.
1. RuntheOutdoorTemperatureSensorwiresthroughaknockoutlocatedonthebottomof
theEPU‐Denclosure.
NOTE:Thesensorwirescanbeextendedupto500feet(152.5meters)usingan18AWG
shielded2‐conductorcable(Heat‐Timerp/n703001‐01orequivalent#18/2cable).
2. ConnecttheOutdoorTemperatureSensorwirestoterminals11and12ontheEPU‐D.
3. Connecttheshieldtoterminal12ontheEPU‐D.
NOTE:Donotconnecttheshieldatthesensorend.
WiringtheOptionalRemoteShutdown/TSTAT
1. RuntheRemoteShutdownwiresthroughaknockoutlocatedonthebottomoftheEPU‐D
enclosure.
2. ConnecttheRemoteShutdowndry‐contactwirestoterminals17and18ontheEPU‐D.
NOTE:Theterminalscanbeconfiguredasnormally‐openornormally‐closed.Ifconnectedto
aremoteshutdown,theterminalsneedan“open”signal.IfconnectedtoaTSTAT,the
terminalsneeda“closed”(short)signal.
Powering‐OntheEPU‐D
1. ApplypowertotheEPU‐D.
2. PlacethePRGM/RUNswitch(1)ontheEPU‐DinthePRGMposition.
3. PerforminitialprogrammingoftheEPU‐D(see“InitialProgrammingoftheEPU‐D”onpage 20).
CompletingtheInstallation
AftertheEPU‐Dispowered‐onandtheinitialprogrammingiscomplete:
1. PlacethePRGM/RUNswitch(1)ontheEPU‐DintheRUNposition.
2. ReplacetheEPU‐Denclosurewiringcoverandsecureitinplacewithtwoscrews.
3. Optionallysecuretheenclosureusingapadlockwithamaximumshankdiameterof⅛".
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20EPU‐DInstallationandOperationManual
059840‐00Rev.A Heat‐TimerCorp.
InitialProgrammingoftheEPU‐D
WhentheEPU‐Disfirstpowered‐onandinitializationiscomplete,theSystemStartupmenuscreensappear.
NOTE:IftheSystemStartupmenuscreensdonotappear,theEPU‐Dhasalreadybeenconfigured.Tocheck
theconfigurationortomakechanges,selectSystem StartupfromtheMainmenu.
ToinitiallyprogramtheEPU‐D:
1. FollowtheSystemStartupmenuscreenstoprogramtheunit(seebelow).
2. Configurethesystemsettings,including:day/nightheatadjustment,day/nightcutofftemperature,boost,
systemsetpoint,andthermallockout(see“SystemSettingsMenu”onpage 29).
3. Settheday/nightscheduletimes(see“SchedulesMenu”onpage 33).
SystemStartupMenu
TheSystemStartupmenuprovidestheoptionsusedtoconfigurebasicsettingsfortheEPU‐D.Thisincludes:
displayunits,sensortype,cyclelength,anddate/timesettings.
DisplayUnit
Selections:°F,°C Default:°F
MenuPath:/SystemStartup>DisplayUnit
Description:
SetsthedisplayofalltemperaturesettingstoFahrenheitorCelsius.