CSE User's Manual

California Simulation Engine

4.34 DHWLOOPHEATER

DHWHEATERLOOP constructs an object representing a hot water heater dedicated to heating DHWLOOP return water (or several if identical).

whName

Optional name of water heater; give after the word “DHWHEATER” if desired.

UnitsLegal RangeDefaultRequiredVariability
63 charactersnoneNoconstant

whMult=integer

Number of identical water heaters of this type. Any value \(>1\) is equivalent to repeated entry of the same DHWHEATER.

UnitsLegal RangeDefaultRequiredVariability
x \(>\) 01Noconstant

whType=choice

Type of water heater. This categorization is based on CEC and federal rating standards that change from time to time.

SMALLSTORAGEA storage water heater having an energy factor (EF) rating. Generally, a gas-fired storage water heater with input of 75,000 Btuh or less, an oil-fired storage water heater with input of 105,000 Btuh or less, an electric storage water heater with input of 12 kW or less, or a heat pump water heater rated at 24 amps or less.
LARGESTORAGEAny storage water heater that is not SMALLSTORAGE.
SMALLINSTANTANEOUSA water heater that has an input rating of at least 4,000 Btuh per gallon of stored water. Small instantaneous water heaters include: gas instantaneous water heaters with an input of 200,000 Btu per hour or less, oil instantaneous water heaters with an input of 210,000 Btu per hour or less, and electric instantaneous water heaters with an input of 12 kW or less.
LARGEINSTANTANEOUSAn instantaneous water heater that does not conform to the definition of SMALLINSTANTANEOUS, an indirect fuel-fired water heater, or a hot water supply boiler.
INSTANTANEOUSUEFAn instantaneous water heater having a UEF rating (as opposed to EF).
UnitsLegal RangeDefaultRequiredVariability
Codes listed aboveSMALLSTORAGENoconstant

whHeatSrc=choice

Heat source for water heater. CSE implements uses efficiency-based models for all whTypes (as documented in RACM, App. B). In addition, the detailed Ecotope HPWH model is available for electric (air source heat pump and resistance) SMALLSTORAGE water heaters.

RESISTANCEElectric resistance heating element Deprecated for whType=SMALLSTORAGE (use RESISTANCEX)
RESISTANCEXElectric resistance heating element, detailed HPWH model
ASHPAir source heat pump, EF model Deprecated for whType=SMALLSTORAGE (use ASHPX)
ASHPXAir source heat pump, detailed HPWH model
FUELFuel-fired burner
UnitsLegal RangeDefaultRequiredVariability
Codes listed aboveFUELNoconstant

whResType=choice

Resistance heater type, valid only if whHeatSrc is equal to RESISTANCEX, else ignored. These choices are supported by the detailed HPWH model. Except for Generic, all heater characteristics are set by HPWH based on whResType.

UnitsLegal RangeDefaultRequiredVariability
Typical SwingTankTypicalNoconstant

whHeatingCap=float

Nominal heating capacity, available only for a limited HPWH types.

UnitsLegal RangeDefaultRequiredVariability
Btuhx \(>\) 00Noconstant

whVol=float

Storage tank volume. Must be omitted or 0 for instantaneous whTypes. Used by HPWH model (whHeatSrc=RESISTANCEX or whHeatSrc=ASHPX). Required when whHeatSrc=RESISTANCEX or whHeatSrc=ASHPX with whASHPType=GENERIC. For all other configurations, whVol is documentation-only.

UnitsLegal RangeDefaultRequiredVariability
gal\(\ge\) 0.1 (caution: small values may cause runtime errors)per whASHPType if HPWH else 50For some HPWH configurations, see aboveconstant

whVolRunning=float

Running storage volume is the volume above aquastat. Requires the total volume based on aquastat position. Ecotope’s HPWH tank and heater.

UnitsLegal RangeDefaultRequiredVariability
galx \(>\) 00Noconstant

whEF=float

Rated energy factor that specifies DHWHEATER efficiency under test conditions. Used by CSE to derive annual water heating efficiency and/or other characteristics as described below. Calculation methods are documented in RACM, Appendix B.

ConfigurationwhEF defaultUse
whType=SMALLSTORAGE, whHeatSrc=RESISTANCE or FUEL0.82Derivation of whLDEF
whType=SMALLSTORAGE, whHeatSrc=ASHP0.82Derivation of whLDEFnote inappropriate default (deprecated, use ASHPX)
whType=SMALLSTORAGE, whHeatSrc=ASHPX, whASHPType=GENERIC(req’d)Tank losses Overall efficiency
whType=SMALLSTORAGE, whHeatSrc=RESISTANCEX(req’d)Tank losses Note: maximum whEF=0.98.
whType=SMALLINSTANTANEOUS, whHeatSrc=RESISTANCE or FUEL0.82Annual efficiency = whEF*0.92
Any other(unused)
UnitsLegal RangeDefaultRequiredVariability
\(>\) 0 Caution: maximum not checked. Unrealistic values will cause runtime errors and/or invalid resultsSee aboveSee aboveconstant

whLDEF=float

Load-dependent energy factor for DHWHEATERs with whType=SMALLSTORAGE and whHeatSrc=FUEL or whHeatSrc=RESISTANCE. If not given, whLDEF is derived using a preliminary simulation activated via DHWSYS wsCalcMode=PRERUN. See RACM Appendix B.

UnitsLegal RangeDefaultRequiredVariability
x \(>\) 0Calculated via DHWSYS PreRun mechanismWhen whType = SMALLSTORAGE and PreRun not usedconstant

whUEF=float

Water heater Uniform Energy Factor efficiency rating, used when whType=INSTANTANEOUSUEF.

UnitsLegal RangeDefaultRequiredVariability
x \(\ge\) 0nonewhen whType= INSTANTANEOUSUEFconstant

whAnnualElec=float

Annual electricity use assumed in UEF rating derivation. Used when whType=INSTANTANEOUSUEF.

UnitsLegal RangeDefaultRequiredVariability
kWhx \(\ge\) 0nonewhen whType= INSTANTANEOUSUEFconstant

whAnnualFuel=float

Annual fuel use assumd in UEF rating derivation, used when whType=INSTANTANEOUSUEF.

UnitsLegal RangeDefaultRequiredVariability
thermsx \(\ge\) 0nonewhen whType= INSTANTANEOUSUEFconstant

whRatedFlow=float

Maximum flow rate assumed in UEF rating derivation. Used when whType=INSTANTANEOUSUEF.

UnitsLegal RangeDefaultRequiredVariability
gpmx \(>\) 0nonewhen whType= INSTANTANEOUSUEFconstant

whStbyElec=float

Instantaneous water heater standby power (electricity consumed when heater is not operating). Used when whType=INSTANTANEOUSUEF.

UnitsLegal RangeDefaultRequiredVariability
Wx \(\ge\) 04Noconstant

whLoadCFwdF=float

Instanteous water heater load carry forward factor – approximate number of hours the heater is allowed to meet water heating demand that is unmet on a 1 minute basis, used when whType=INSTANTANEOUSUEF.

UnitsLegal RangeDefaultRequiredVariability
x \(\ge\) 01Noconstant

whZone=znName

Name of zone where water heater is located, used only in detailed HPWH models (whHeatSrc=ASHPX or whHeatSrc=RESISTANCEX), otherwise no effect. Zone conditions are used for tank heat loss calculations. Heat losses from the DHWHEATER are included in the zone heat balance. whZone also provides the default for whASHPSrcZn (see below).

whZone and whTEx cannot both be specified.

UnitsLegal RangeDefaultRequiredVariability
name of a ZONENot in a zone (heat losses discarded)Noconstant

whTEx=float

Water heater surround temperature, used only in detailed HPWH models (whHeatSrc=ASHPX or whHeatSrc=RESISTANCEX), otherwise no effect. When whTEx is specified, tank heat losses are calculated using whTEx and modify tank water temperatures, but the lost heat has no external effect.

whZone and whTEx cannot both be specified.

UnitsLegal RangeDefaultRequiredVariability
oFx \(\ge\) 0whZone air temperature if specified, else 70 oFNohourly

whASHPType=choice

Air source heat pump type, valid only if whHeatSrc=ASHPX. These choices are supported by the detailed HPWH model. Except for Generic, all heater characteristics are set by HPWH based on whASHPType.

ChoiceSpecified type
GenericGeneral generic (parameterized by wh_EF and wh_vol)
AOSmithPHPT6060 gallon Voltex
AOSmithPHPT8080 gallon Voltex
AOSmithHPTU5050 gallon AOSmith HPTU
AOSmithHPTU6666 gallon AOSmith HPTU
AOSmithHPTU8080 gallon AOSmith HPTU
AOSmithHPTU80DR80 gallon AOSmith HPTU (demand reduction variant)
AOSmithCAHP120120 gallon AOSmith
Sanden40Sanden 40 gallon CO2 external heat pump
Sanden80Sanden 80 gallon CO2 external heat pump
Sanden120Sanden 120 gallon CO2 external heat pump
SandenGS3Sanden GS3 compressor CO2 external
GE20122012 era GeoSpring
GE20142014 80 gal GE model run in the efficiency mode
GE2014_80DR2014 80 gal GE model run in the efficiency mode (demand reduction variant)
GE2014StdMode2014 50 gal GE run in standard mode
GE2014StdMode802014 80 gal GE run in standard mode
RheemHB50newish Rheem (2014 model?)
RheemHBDR225050 gallon, 2250 W resistance Rheem HB Duct Ready
RheemHBDR455050 gallon, 4500 W resistance Rheem HB Duct Ready
RheemHBDR226565 gallon, 2250 W resistance Rheem HB Duct Ready
RheemHBDR456565 gallon, 4500 W resistance Rheem HB Duct Ready
RheemHBDR228080 gallon, 2250 W resistance Rheem HB Duct Ready
RheemHBDR458080 gallon, 4500 W resistance Rheem HB Duct Ready
Rheem2020Prem4040 gallon, Rheem 2020 Premium
Rheem2020Prem5050 gallon, Rheem 2020 Premium
Rheem2020Prem6565 gallon, Rheem 2020 Premium
Rheem2020Prem8080 gallon, Rheem 2020 Premium
Rheem2020Build4040 gallon, Rheem 2020 Builder
Rheem2020Build5050 gallon, Rheem 2020 Builder
Rheem2020Build6565 gallon, Rheem 2020 Builder
Rheem2020Build8080 gallon, Rheem 2020 Builder
RheemPlugInShared4040 gal Rheem plug-in 120V shared circuit (no resistance elements)
RheemPlugInShared5050 gal Rheem plug-in 120V shared circuit (no resistance elements)
RheemPlugInShared6565 gal Rheem plug-in 120V shared circuit (no resistance elements)
RheemPlugInShared8080 gal Rheem plug-in 120V shared circuit (no resistance elements)
RheemPlugInDedicated4040 gal Rheem plug-in 120V dedicated circuit (no resistance elements)
RheemPlugInDedicated5050 gal Rheem plug-in 120V dedicated circuit (no resistance elements)
Stiebel220EStiebel Eltron (2014 model?)
AOSmithSHPT50AOSmith add’l models (added 3-24-2017)
AOSmithSHPT66AOSmith add’l models (added 3-24-2017)
AOSmithSHPT80AOSmith add’l models (added 3-24-2017)
GenericTier1Generic Tier 1
GenericTier2Generic Tier 2
GenericTier3Generic Tier 3
GenericGeneral generic (parameterized by EF and vol)
UEF2GenericExperimental UEF=2
WorstCaseMediumUEF2Generic alias (supports pre-existing test cases)
BasicIntegratedTypical integrated HPWH
ResTankResistance heater (no compressor). Superceded by whHeatSrc=RESITANCEX
ResTankNoUAResistance heater (no compressor) with no tank losses. Superseded by whHeatSrc=RESISTANCEX.
AOSmithHPTU80DR80 gallon AOSmith HPTU with fixed backup setpoint (experimental for demand response testing)
AOSmithSHPT5050 gal AOSmith SHPT
AOSmithSHPT6666 gal AOSmith SHPT
AOSmithSHPT8080 gal AOSmith SHPT
AOSmithHPTS4040 gal AOSmith HPTS
AOSmithHPTS5050 gal AOSmith HPTS
AOSmithHPTS6666 gal AOSmith HPTS
AOSmithHPTS8080 gal AOSmith HPTS
ColmacCxV5_SPColmac CxA-xx modular external HPWHs (single pass mode)
ColmacCxA10_SPColmac CxA-xx modular external HPWHs (single pass mode)
ColmacCxA15_SPColmac CxA-xx modular external HPWHs (single pass mode)
ColmacCxA20_SPColmac CxA-xx modular external HPWHs (single pass mode)
ColmacCxA25_SPColmac CxA-xx modular external HPWHs (single pass mode)
ColmacCxA30_SPColmac CxA-xx modular external HPWHs (single pass mode)
ColmacCxV5_MPColmac CxA-xx modular external HPWHs (multi-pass mode)
ColmacCxA10_MPColmac CxA-xx modular external HPWHs (multi-pass mode)
ColmacCxA15_MPColmac CxA-xx modular external HPWHs (multi-pass mode)
ColmacCxA20_MPColmac CxA-xx modular external HPWHs (multi-pass mode)
ColmacCxA25_MPColmac CxA-xx modular external HPWHs (multi-pass mode)
ColmacCxA30_MPColmac CxA-xx modular external HPWHs (multi-pass mode)
NyleC25A_SPNyle Cxx external HPWHs (SP = single pass mode)
NyleC60A_SPNyle Cxx external HPWHs (SP = single pass mode)
NyleC90A_SPNyle Cxx external HPWHs (SP = single pass mode)
NyleC125A_SPNyle Cxx external HPWHs (SP = single pass mode)
NyleC185A_SPNyle Cxx external HPWHs (SP = single pass mode)
NyleC250A_SPNyle Cxx external HPWHs (SP = single pass mode)
NyleC60A_CWP_SPNyle Cxx external SP HPWHs with cold weather package
NyleC90A_CWP_SPNyle Cxx external SP HPWHs with cold weather package
NyleC125A_CWP_SPNyle Cxx external SP HPWHs with cold weather package
NyleC185A_CWP_SPNyle Cxx external SP HPWHs with cold weather package
NyleC250A_CWP_SPNyle Cxx external SP HPWHs with cold weather package
NyleC60A_MPNyle Cxx external HPWHs (MP = multi-pass mode)
NyleC90A_MPNyle Cxx external HPWHs (MP = multi-pass mode)
NyleC125A_MPNyle Cxx external HPWHs (MP = multi-pass mode)
NyleC185A_MPNyle Cxx external HPWHs (MP = multi-pass mode)
NyleC250A_MPNyle Cxx external HPWHs (MP = multi-pass mode)
NyleC60A_CWP_MPNyle Cxx external MP HPWHs w/ cold weather package
NyleC90A_CWP_MPNyle Cxx external MP HPWHs w/ cold weather package
NyleC125A_CWP_MPNyle Cxx external MP HPWHs w/ cold weather package
NyleC185A_CWP_MPNyle Cxx external MP HPWHs w/ cold weather package
NyleC250A_CWP_MPNyle Cxx external MP HPWHs w/ cold weather package
Rheem_HPHD60HNU_MPRheem HPHD60 MP external MP HPWHs
Rheem_HPHD60VNU_MPRheem HPHD60 MP external MP HPWHs
Rheem_HPHD135HNU_MPRheem HPHD135 MP external MP HPWHs
Rheem_HPHD135VNU_MPRheem HPHD135 MP external MP HPWHs
Scalable_SPsingle pass scalable type for autosized standard design
Scalable_MPmultipass scalable type for autosized standard design
AquaThermAireVillara AquaThermAire HPWH
GenericUEF21765-gal tank meeting Federal standard minimum requirement
AWHSTier4Generic40Any 40-gal tank meeting Advanced Water Heating Specification Tier-4 minimum requirements
AWHSTier4Generic50Any 50-gal tank meeting Advanced Water Heating Specification Tier-4 minimum requirements
AWHSTier4Generic65Any 65-gal tank meeting Advanced Water Heating Specification Tier-4 minimum requirements
AWHSTier4Generic80Any 80-gal tank meeting Advanced Water Heating Specification Tier-4 minimum requirements
BradfordWhiteAeroThermRE2H50Bradford White 50-gal AeroTherm2023
BradfordWhiteAeroThermRE2H65Bradford White 65-gal AeroTherm2023
BradfordWhiteAeroThermRE2H80Bradford White 80-gal AeroTherm2023
LG_APHWC50LG 50-gal integrated HPWH
LG_APHWC80LG 580-gal integrated HPWH
UnitsLegal RangeDefaultRequiredVariability
Codes listed abovenoneWhen whHeatSrc=ASHPXconstant

whASHPSrcZn=znName

Name of zone that serves as heat pump heat source used when whHeatSrc=ASHPX. Heat removed from the zone is added to the heated water and is included in zone heat balance (that is, heat pump operation cools the zone).

whASHPSrcZn and whASHPSrcT cannot both be specified.

UnitsLegal RangeDefaultRequiredVariability
name of a ZONEwhZoneIf no zone is specified by input or default, heat extracted by ASHP has no effect.Noconstant

whASHPSrcT=float

Heat pump source air temperature used when whHeatSrc=ASHPX. Heat removed from this source is added to the heated water but has no other effect.

whASHPSrcZn and whASHPSrcT cannot both be specified.

The logic to determine the temperature of the heat pump source air is:

        if whASHPSrcT is specified
          use whASHPSrcT
        else if whASHPSRCZn is specified
          use whASHPSrcZn air temp
        else if whZone is specified
          use whZone air temp
        else
          use 70 F

To model a heat pump that uses outdoor air as its heat source, omit whASHPSrcZn and specify whASHPSrcT = $tDbO.

UnitsLegal RangeDefaultRequiredVariability
oFx \(\ge\) 070 oF (used only when whASHPSrcZn and whZone not specified)Nohourly

whASHPResUse=float

Specifies activation temperature difference for resistance heating, used only when whHeatSrc=ASHPX and whASHPType=GENERIC. Refer to HPWH engineering documentation for model details.

UnitsLegal RangeDefaultRequiredVariability
oCx \(\ge\) 07.22Noconstant

whResHtPwr=float

Specifies resistance upper element power, used only with whHeatSrc=RESISTANCEX.

UnitsLegal RangeDefaultRequiredVariability
Wx \(\ge\) 04500Noconstant

whResHtPwr2=float

Specifies resistance lower element power, used only with whHeatSrc=RESISTANCEX.

UnitsLegal RangeDefaultRequiredVariability
Wx \(\ge\) 0whResHtPwrNoconstant

whUA=float

HPWH-type total UA (not per tank)

UnitsLegal RangeDefaultRequiredVariability
Btuh/Fx \(\geq\) 0HPWH defaultNoconstant

whInsulR=float

Tank insulation resistance for heat pump water heater.

UnitsLegal RangeDefaultRequiredVariability
hr-F/Btuhx \(>\) 0-1Noconstant

whInHtSupply=float
whInHtLoopRet=float

Fractional tank height of inlets for supply water and DHWLOOP return, used only with HPWH types (whHeatSrc=RESISTANCEX or whHeatSrc=ASHPX). 0 indicates the bottom of the water heater tank and 1 specifies the top. Inlet height influences tank layer mixing and can impact heat pump COP and/or heating activation frequency.

UnitsLegal RangeDefaultRequiredVariability
0 \(\le\) x \(\le\) 1HPWH default (0?)Noconstant

whtankCount=float

Number of storage tanks per DHWHEATER, re built-up whType=Builtup, does not reflect wh_mult (wh_mult=2, wh_tankCount=3 -> 6 tanks).

UnitsLegal RangeDefaultRequiredVariability
#x \(\geq\) 11Noconstant

whEff=float

Water heating efficiency, used in modeling whType=LARGESTORAGE and whType=LARGEINSTANTANEOUS.

UnitsLegal RangeDefaultRequiredVariability
0 \(<\) whEff \(\leq\) 1.82Noconstant

whSBL=float

Standby loss, used in modeling whType=LARGESTORAGE.

UnitsLegal RangeDefaultRequiredVariability
Btuhx \(\ge\) 00Noconstant

whPilotPwr=float

Pilot light consumption, included in fuel energy use of DHWHEATERs with whHeatSrc=FUEL.

UnitsLegal RangeDefaultRequiredVariability
Btuhx \(\ge\) 00Nohourly

whParElec=float

Parasitic electricity power, included in electrical energy use of all DHWHEATERs.

UnitsLegal RangeDefaultRequiredVariability
Wx \(\ge\) 00Nohourly

whFAdjElec=float
whFAdjFuel=float

Water heater energy use modifiers. Multiplies calculated use of electricity (whFAdjElec) and fuel (whFAdjFuel). All components of energy use – primary, backup, XBU (extra backup), and other auxiliary – are modified before they are accumulated to whElecMtr and whFuelMtr.

UnitsLegal RangeDefaultRequiredVariability
\(\ge\) 01Nosubhourly

whElecMtr=mtrName

Name of METER object, if any, by which DHWHEATER electrical energy use is recorded (under end use DHW).

UnitsLegal RangeDefaultRequiredVariability
name of a METERParent DHWSYS wsElecMtrNoconstant

whxBUEndUse=choice

Specifies the whElecMtr end use, if any, to which extra backup energy is accumulated. In some water heater types, extra backup energy is modeled to maintain output temperature at wsTUse. By default, extra backup energy is included in end use dhwBU. whxBUEndUse allows specification of an alternative end use to which extra backup energy is accumulated.

UnitsLegal RangeDefaultRequiredVariability
end use code(extra backup accums to dhwBU)Noconstant

whFuelMtr =mtrName

Name of METER object, if any, by which DHWHEATER fuel energy use is recorded (under end use DHW).

UnitsLegal RangeDefaultRequiredVariability
name of a METERParent DHWSYS wsFuelMtrNoconstant

whTankTInit =comma-separated list of 12 floats

A list of 12 initial values for HPWH tank model layer temperatures, in bottom-to-top order. If given, these values are used to initialize tank layer temperatures at the beginning of the warmup period. Initialization is not repeated at the beginning of the main simulation.

whTankTInit is allowed only for HPWH-based types (whHeatSrc=ASHPX or whHeatSrc=ResistanceX).

whTankTInit is intended for use in empirical validation studies where the initial tank state needs to match measured data. whTankTInit should not be generally used. In the absence of whTankTInit, layer temperatures are initialized to the water heater setpoint inherited from the parent DHWSYS.

UnitsLegal RangeDefaultRequiredVariability
oFx \(\gt\) 0Noconstant

endDHWHEATER

Optionally indicates the end of the DHWHEATER definition.

UnitsLegal RangeDefaultRequiredVariability
x \(\geq\) 0noneNo

Related Probes: