4.30 DHWHEATER
DHWHEATER constructs an object representing a domestic hot water heater (or several if identical).
whName
Optional name of water heater; give after the word “DHWHEATER” if desired.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| 63 characters | none | No | constant |
whMult=integer
Number of identical water heaters of this type. Any value \(>1\) is equivalent to repeated entry of the same DHWHEATER.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| x \(>\) 0 | 1 | No | constant |
whType=choice
Type of water heater. This categorization is based on CEC and federal rating standards that change from time to time.
| SMALLSTORAGE | A 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. |
| LARGESTORAGE | Any storage water heater that is not SMALLSTORAGE. |
| SMALLINSTANTANEOUS | A 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. |
| LARGEINSTANTANEOUS | An instantaneous water heater that does not conform to the definition of SMALLINSTANTANEOUS, an indirect fuel-fired water heater, or a hot water supply boiler. |
| INSTANTANEOUSUEF | An instantaneous water heater having a UEF rating (as opposed to EF). |
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| Codes listed above | SMALLSTORAGE | No | constant |
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.
| RESISTANCE | Electric resistance heating element Deprecated for whType=SMALLSTORAGE (use RESISTANCEX) |
| RESISTANCEX | Electric resistance heating element, detailed HPWH model |
| ASHP | Air source heat pump, EF model Deprecated for whType=SMALLSTORAGE (use ASHPX) |
| ASHPX | Air source heat pump, detailed HPWH model |
| FUEL | Fuel-fired burner |
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| Codes listed above | FUEL | No | constant |
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.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| Typical SwingTank | Typical | No | constant |
whHeatingCap=float
Nominal heating capacity, available only for a limited HPWH types.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| Btuh | x \(>\) 0 | 0 | No | constant |
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.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| gal | \(\ge\) 0.1 (caution: small values may cause runtime errors) | per whASHPType if HPWH else 50 | For some HPWH configurations, see above | constant |
whVolRunning=float
Running storage volume is the volume above aquastat. Requires the total volume based on aquastat position. Ecotope’s HPWH tank and heater.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| gal | x \(>\) 0 | 0 | No | constant |
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.
| Configuration | whEF default | Use |
|---|---|---|
| whType=SMALLSTORAGE, whHeatSrc=RESISTANCE or FUEL | 0.82 | Derivation of whLDEF |
| whType=SMALLSTORAGE, whHeatSrc=ASHP | 0.82 | Derivation 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 FUEL | 0.82 | Annual efficiency = whEF*0.92 |
| Any other | (unused) |
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| \(>\) 0 Caution: maximum not checked. Unrealistic values will cause runtime errors and/or invalid results | See above | See above | constant |
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.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| x \(>\) 0 | Calculated via DHWSYS PreRun mechanism | When whType = SMALLSTORAGE and PreRun not used | constant |
whUEF=float
Water heater Uniform Energy Factor efficiency rating, used when whType=INSTANTANEOUSUEF.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| x \(\ge\) 0 | none | when whType= INSTANTANEOUSUEF | constant |
whAnnualElec=float
Annual electricity use assumed in UEF rating derivation. Used when whType=INSTANTANEOUSUEF.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| kWh | x \(\ge\) 0 | none | when whType= INSTANTANEOUSUEF | constant |
whAnnualFuel=float
Annual fuel use assumd in UEF rating derivation, used when whType=INSTANTANEOUSUEF.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| therms | x \(\ge\) 0 | none | when whType= INSTANTANEOUSUEF | constant |
whRatedFlow=float
Maximum flow rate assumed in UEF rating derivation. Used when whType=INSTANTANEOUSUEF.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| gpm | x \(>\) 0 | none | when whType= INSTANTANEOUSUEF | constant |
whStbyElec=float
Instantaneous water heater standby power (electricity consumed when heater is not operating). Used when whType=INSTANTANEOUSUEF.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| W | x \(\ge\) 0 | 4 | No | constant |
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.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| x \(\ge\) 0 | 1 | No | constant |
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.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| name of a ZONE | Not in a zone (heat losses discarded) | No | constant |
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.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| oF | x \(\ge\) 0 | whZone air temperature if specified, else 70 oF | No | hourly |
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.
| Choice | Specified type |
|---|---|
| Generic | General generic (parameterized by wh_EF and wh_vol) |
| AOSmithPHPT60 | 60 gallon Voltex |
| AOSmithPHPT80 | 80 gallon Voltex |
| AOSmithHPTU50 | 50 gallon AOSmith HPTU |
| AOSmithHPTU66 | 66 gallon AOSmith HPTU |
| AOSmithHPTU80 | 80 gallon AOSmith HPTU |
| AOSmithHPTU80DR | 80 gallon AOSmith HPTU (demand reduction variant) |
| AOSmithCAHP120 | 120 gallon AOSmith |
| Sanden40 | Sanden 40 gallon CO2 external heat pump |
| Sanden80 | Sanden 80 gallon CO2 external heat pump |
| Sanden120 | Sanden 120 gallon CO2 external heat pump |
| SandenGS3 | Sanden GS3 compressor CO2 external |
| GE2012 | 2012 era GeoSpring |
| GE2014 | 2014 80 gal GE model run in the efficiency mode |
| GE2014_80DR | 2014 80 gal GE model run in the efficiency mode (demand reduction variant) |
| GE2014StdMode | 2014 50 gal GE run in standard mode |
| GE2014StdMode80 | 2014 80 gal GE run in standard mode |
| RheemHB50 | newish Rheem (2014 model?) |
| RheemHBDR2250 | 50 gallon, 2250 W resistance Rheem HB Duct Ready |
| RheemHBDR4550 | 50 gallon, 4500 W resistance Rheem HB Duct Ready |
| RheemHBDR2265 | 65 gallon, 2250 W resistance Rheem HB Duct Ready |
| RheemHBDR4565 | 65 gallon, 4500 W resistance Rheem HB Duct Ready |
| RheemHBDR2280 | 80 gallon, 2250 W resistance Rheem HB Duct Ready |
| RheemHBDR4580 | 80 gallon, 4500 W resistance Rheem HB Duct Ready |
| Rheem2020Prem40 | 40 gallon, Rheem 2020 Premium |
| Rheem2020Prem50 | 50 gallon, Rheem 2020 Premium |
| Rheem2020Prem65 | 65 gallon, Rheem 2020 Premium |
| Rheem2020Prem80 | 80 gallon, Rheem 2020 Premium |
| Rheem2020Build40 | 40 gallon, Rheem 2020 Builder |
| Rheem2020Build50 | 50 gallon, Rheem 2020 Builder |
| Rheem2020Build65 | 65 gallon, Rheem 2020 Builder |
| Rheem2020Build80 | 80 gallon, Rheem 2020 Builder |
| RheemPlugInShared40 | 40 gal Rheem plug-in 120V shared circuit (no resistance elements) |
| RheemPlugInShared50 | 50 gal Rheem plug-in 120V shared circuit (no resistance elements) |
| RheemPlugInShared65 | 65 gal Rheem plug-in 120V shared circuit (no resistance elements) |
| RheemPlugInShared80 | 80 gal Rheem plug-in 120V shared circuit (no resistance elements) |
| RheemPlugInDedicated40 | 40 gal Rheem plug-in 120V dedicated circuit (no resistance elements) |
| RheemPlugInDedicated50 | 50 gal Rheem plug-in 120V dedicated circuit (no resistance elements) |
| Stiebel220E | Stiebel Eltron (2014 model?) |
| AOSmithSHPT50 | AOSmith add’l models (added 3-24-2017) |
| AOSmithSHPT66 | AOSmith add’l models (added 3-24-2017) |
| AOSmithSHPT80 | AOSmith add’l models (added 3-24-2017) |
| GenericTier1 | Generic Tier 1 |
| GenericTier2 | Generic Tier 2 |
| GenericTier3 | Generic Tier 3 |
| Generic | General generic (parameterized by EF and vol) |
| UEF2Generic | Experimental UEF=2 |
| WorstCaseMedium | UEF2Generic alias (supports pre-existing test cases) |
| BasicIntegrated | Typical integrated HPWH |
| ResTank | Resistance heater (no compressor). Superceded by whHeatSrc=RESITANCEX |
| ResTankNoUA | Resistance heater (no compressor) with no tank losses. Superseded by whHeatSrc=RESISTANCEX. |
| AOSmithHPTU80DR | 80 gallon AOSmith HPTU with fixed backup setpoint (experimental for demand response testing) |
| AOSmithSHPT50 | 50 gal AOSmith SHPT |
| AOSmithSHPT66 | 66 gal AOSmith SHPT |
| AOSmithSHPT80 | 80 gal AOSmith SHPT |
| ColmacCxV5_SP | Colmac CxA-xx modular external HPWHs (single pass mode) |
| ColmacCxA10_SP | Colmac CxA-xx modular external HPWHs (single pass mode) |
| ColmacCxA15_SP | Colmac CxA-xx modular external HPWHs (single pass mode) |
| ColmacCxA20_SP | Colmac CxA-xx modular external HPWHs (single pass mode) |
| ColmacCxA25_SP | Colmac CxA-xx modular external HPWHs (single pass mode) |
| ColmacCxA30_SP | Colmac CxA-xx modular external HPWHs (single pass mode) |
| ColmacCxV5_MP | Colmac CxA-xx modular external HPWHs (multi-pass mode) |
| ColmacCxA10_MP | Colmac CxA-xx modular external HPWHs (multi-pass mode) |
| ColmacCxA15_MP | Colmac CxA-xx modular external HPWHs (multi-pass mode) |
| ColmacCxA20_MP | Colmac CxA-xx modular external HPWHs (multi-pass mode) |
| ColmacCxA25_MP | Colmac CxA-xx modular external HPWHs (multi-pass mode) |
| ColmacCxA30_MP | Colmac CxA-xx modular external HPWHs (multi-pass mode) |
| NyleC25A_SP | Nyle Cxx external HPWHs (SP = single pass mode) |
| NyleC60A_SP | Nyle Cxx external HPWHs (SP = single pass mode) |
| NyleC90A_SP | Nyle Cxx external HPWHs (SP = single pass mode) |
| NyleC125A_SP | Nyle Cxx external HPWHs (SP = single pass mode) |
| NyleC185A_SP | Nyle Cxx external HPWHs (SP = single pass mode) |
| NyleC250A_SP | Nyle Cxx external HPWHs (SP = single pass mode) |
| NyleC60A_CWP_SP | Nyle Cxx external SP HPWHs with cold weather package |
| NyleC90A_CWP_SP | Nyle Cxx external SP HPWHs with cold weather package |
| NyleC125A_CWP_SP | Nyle Cxx external SP HPWHs with cold weather package |
| NyleC185A_CWP_SP | Nyle Cxx external SP HPWHs with cold weather package |
| NyleC250A_CWP_SP | Nyle Cxx external SP HPWHs with cold weather package |
| NyleC60A_MP | Nyle Cxx external HPWHs (MP = multi-pass mode) |
| NyleC90A_MP | Nyle Cxx external HPWHs (MP = multi-pass mode) |
| NyleC125A_MP | Nyle Cxx external HPWHs (MP = multi-pass mode) |
| NyleC185A_MP | Nyle Cxx external HPWHs (MP = multi-pass mode) |
| NyleC250A_MP | Nyle Cxx external HPWHs (MP = multi-pass mode) |
| NyleC60A_CWP_MP | Nyle Cxx external MP HPWHs w/ cold weather package |
| NyleC90A_CWP_MP | Nyle Cxx external MP HPWHs w/ cold weather package |
| NyleC125A_CWP_MP | Nyle Cxx external MP HPWHs w/ cold weather package |
| NyleC185A_CWP_MP | Nyle Cxx external MP HPWHs w/ cold weather package |
| NyleC250A_CWP_MP | Nyle Cxx external MP HPWHs w/ cold weather package |
| Rheem_HPHD60HNU_MP | Rheem HPHD60 MP external MP HPWHs |
| Rheem_HPHD60VNU_MP | Rheem HPHD60 MP external MP HPWHs |
| Rheem_HPHD135HNU_MP | Rheem HPHD135 MP external MP HPWHs |
| Rheem_HPHD135VNU_MP | Rheem HPHD135 MP external MP HPWHs |
| Scalable_SP | single pass scalable type for autosized standard design |
| Scalable_MP | multipass scalable type for autosized standard design |
| AquaThermAire | Vallara AquaThermAire HPWH |
| GenericUEF217 | 65-gal tank meeting Federal standard minimum requirement |
| AWHSTier4Generic40 | Any 40-gal tank meeting Advanced Water Heating Specification Tier-4 minimum requirements |
| AWHSTier4Generic50 | Any 50-gal tank meeting Advanced Water Heating Specification Tier-4 minimum requirements |
| AWHSTier4Generic65 | Any 65-gal tank meeting Advanced Water Heating Specification Tier-4 minimum requirements |
| AWHSTier4Generic80 | Any 80-gal tank meeting Advanced Water Heating Specification Tier-4 minimum requirements |
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| Codes listed above | none | When whHeatSrc=ASHPX | constant |
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.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| name of a ZONE | whZoneIf no zone is specified by input or default, heat extracted by ASHP has no effect. | No | constant |
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 FTo model a heat pump that uses outdoor air as its heat source, omit whASHPSrcZn and specify whASHPSrcT = $tDbO.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| oF | x \(\ge\) 0 | 70 oF (used only when whASHPSrcZn and whZone not specified) | No | hourly |
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.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| oC | x \(\ge\) 0 | 7.22 | No | constant |
whResHtPwr=float
Specifies resistance upper element power, used only with whHeatSrc=RESISTANCEX.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| W | x \(\ge\) 0 | 4500 | No | constant |
whResHtPwr2=float
Specifies resistance lower element power, used only with whHeatSrc=RESISTANCEX.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| W | x \(\ge\) 0 | whResHtPwr | No | constant |
whUA=float
HPWH-type total UA (not per tank)
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| Btuh/F | x \(\geq\) 0 | HPWH default | No | constant |
whInsulR=float
Tank insulation resistance for heat pump water heater.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| hr-F/Btuh | x \(>\) 0 | -1 | No | constant |
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.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| 0 \(\le\) x \(\le\) 1 | HPWH default (0?) | No | constant |
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).
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| # | x \(\geq\) 1 | 1 | No | constant |
whEff=float
Water heating efficiency, used in modeling whType=LARGESTORAGE and whType=LARGEINSTANTANEOUS.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| 0 \(<\) whEff \(\leq\) 1 | .82 | No | constant |
whSBL=float
Standby loss, used in modeling whType=LARGESTORAGE.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| Btuh | x \(\ge\) 0 | 0 | No | constant |
whPilotPwr=float
Pilot light consumption, included in fuel energy use of DHWHEATERs with whHeatSrc=FUEL.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| Btuh | x \(\ge\) 0 | 0 | No | hourly |
whParElec=float
Parasitic electricity power, included in electrical energy use of all DHWHEATERs.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| W | x \(\ge\) 0 | 0 | No | hourly |
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.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| \(\ge\) 0 | 1 | No | subhourly |
whElecMtr=mtrName
Name of METER object, if any, by which DHWHEATER electrical energy use is recorded (under end use DHW).
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| name of a METER | Parent DHWSYS wsElecMtr | No | constant |
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.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| end use code | (extra backup accums to dhwBU) | No | constant |
whFuelMtr =mtrName
Name of METER object, if any, by which DHWHEATER fuel energy use is recorded (under end use DHW).
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| name of a METER | Parent DHWSYS wsFuelMtr | No | constant |
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.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| oF | x \(\gt\) 0 | No | constant |
endDHWHEATER
Optionally indicates the end of the DHWHEATER definition.
| Units | Legal Range | Default | Required | Variability |
|---|---|---|---|---|
| x \(\geq\) 0 | none | No |
Related Probes: