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Fix Coil:Cooling:DX cannot mimic Coil:Cooling:DX:MultiSpeed PLF > 1 behavior #11448

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Fix Coil:Cooling:DX cannot mimic Coil:Cooling:DX:MultiSpeed PLF > 1 behavior #11448

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5a83db6
Add new Apply PLF field to Coil:Cooling:DX:CurveFit:OperatingMode.
joseph-robertson Mar 5, 2026
b2947ac
Introduce new bool for using Apply PLF field.
joseph-robertson Mar 5, 2026
4b6bf5c
Stub input transition rules for new Apply PLF field.
joseph-robertson Mar 5, 2026
d19a253
Transition all testfiles with Coil:Cooling:DX.
joseph-robertson Mar 5, 2026
0b872aa
Update CoilCoolingDX unit test files for new field.
joseph-robertson Mar 5, 2026
3795dde
Formatting.
joseph-robertson Mar 5, 2026
39d828e
Update various unit tests with new field default.
joseph-robertson Mar 5, 2026
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29 changes: 17 additions & 12 deletions idd/Energy+.idd.in
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Original file line number Diff line number Diff line change
Expand Up @@ -52276,12 +52276,17 @@ Coil:Cooling:DX:CurveFit:OperatingMode,
\minimum 0.0
\maximum 3000.0
\default 0.0
A2, \field Apply Latent Degradation to Speeds Greater than 1
A2, \field Apply Part Load Fraction to Speeds Greater than 1
\type choice
\key Yes
\key No
\default Yes
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@rraustad rraustad Mar 5, 2026

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I was thinking that the default should be the same as the Multispeed object and the transition could insert Yes. What do you think?

Coil:Cooling:DX:MultiSpeed,
    A9 , \field Apply Part Load Fraction to Speeds Greater than 1
       \type choice
       \key Yes
       \key No
       \default No

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@shorowit shorowit Mar 5, 2026

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I agree that No should be the default. And I personally think the transition should use the default (even though it will result in diffs), but I can see arguments for both sides.

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@rraustad rraustad Mar 6, 2026

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I would not have a problem with using the default of No.

A3, \field Apply Latent Degradation to Speeds Greater than 1
\type choice
\key Yes
\key No
\default No
A3, \field Condenser Type
A4, \field Condenser Type
\type choice
\key AirCooled
\key EvaporativelyCooled
Expand All @@ -52297,35 +52302,35 @@ Coil:Cooling:DX:CurveFit:OperatingMode,
\note Must be lower than or equal to the highest speed number.
\note If blank, defaults to the highest speed number used.
\type integer
A4, \field Speed 1 Name
A5, \field Speed 1 Name
\required-field
\type object-list
\object-list DXCoolingSpeedNames
A5, \field Speed 2 Name
A6, \field Speed 2 Name
\type object-list
\object-list DXCoolingSpeedNames
A6, \field Speed 3 Name
A7, \field Speed 3 Name
\type object-list
\object-list DXCoolingSpeedNames
A7, \field Speed 4 Name
A8, \field Speed 4 Name
\type object-list
\object-list DXCoolingSpeedNames
A8, \field Speed 5 Name
A9, \field Speed 5 Name
\type object-list
\object-list DXCoolingSpeedNames
A9, \field Speed 6 Name
A10, \field Speed 6 Name
\type object-list
\object-list DXCoolingSpeedNames
A10, \field Speed 7 Name
A11, \field Speed 7 Name
\type object-list
\object-list DXCoolingSpeedNames
A11, \field Speed 8 Name
A12, \field Speed 8 Name
\type object-list
\object-list DXCoolingSpeedNames
A12, \field Speed 9 Name
A13, \field Speed 9 Name
\type object-list
\object-list DXCoolingSpeedNames
A13; \field Speed 10 Name
A14; \field Speed 10 Name
\type object-list
\object-list DXCoolingSpeedNames

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24 changes: 19 additions & 5 deletions src/EnergyPlus/Coils/CoilCoolingDXCurveFitOperatingMode.cc
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Expand Up @@ -81,6 +81,11 @@ void CoilCoolingDXCurveFitOperatingMode::instantiateFromInputSpec(EnergyPlus::En
this->evapRateRatio = input_data.ratio_of_initial_moisture_evaporation_rate_and_steady_state_latent_capacity;
this->maxCyclingRate = input_data.maximum_cycling_rate;
this->latentTimeConst = input_data.latent_capacity_time_constant;
if (Util::SameString(input_data.apply_part_load_fraction_to_speeds_greater_than_1, "Yes")) {
this->applyPartLoadFractionAllSpeeds = true;
} else {
this->applyPartLoadFractionAllSpeeds = false;
}
if (Util::SameString(input_data.apply_latent_degradation_to_speeds_greater_than_1, "Yes")) {
this->applyLatentDegradationAllSpeeds = true;
} else {
Expand Down Expand Up @@ -157,11 +162,12 @@ CoilCoolingDXCurveFitOperatingMode::CoilCoolingDXCurveFitOperatingMode(EnergyPlu
input_specs.ratio_of_initial_moisture_evaporation_rate_and_steady_state_latent_capacity = state.dataIPShortCut->rNumericArgs(5);
input_specs.latent_capacity_time_constant = state.dataIPShortCut->rNumericArgs(6);
input_specs.nominal_time_for_condensate_removal_to_begin = state.dataIPShortCut->rNumericArgs(7);
input_specs.apply_latent_degradation_to_speeds_greater_than_1 = state.dataIPShortCut->cAlphaArgs(2);
input_specs.condenser_type = state.dataIPShortCut->cAlphaArgs(3);
input_specs.apply_part_load_fraction_to_speeds_greater_than_1 = state.dataIPShortCut->cAlphaArgs(2);
input_specs.apply_latent_degradation_to_speeds_greater_than_1 = state.dataIPShortCut->cAlphaArgs(3);
input_specs.condenser_type = state.dataIPShortCut->cAlphaArgs(4);
input_specs.nominal_evap_condenser_pump_power = state.dataIPShortCut->rNumericArgs(8);
input_specs.nominal_speed_number = state.dataIPShortCut->rNumericArgs(9);
for (int fieldNum = 4; fieldNum <= NumAlphas; fieldNum++) {
for (int fieldNum = 5; fieldNum <= NumAlphas; fieldNum++) {
if (state.dataIPShortCut->cAlphaArgs(fieldNum).empty()) {
break;
}
Expand Down Expand Up @@ -376,7 +382,11 @@ void CoilCoolingDXCurveFitOperatingMode::CalcOperatingMode(EnergyPlus::EnergyPlu
}

OpModeRTF = thisspeed.RTF;
OpModePower = thisspeed.fullLoadPower * thisspeed.RTF;
if ((!this->applyPartLoadFractionAllSpeeds) && (speedNum > 1)) {
OpModePower = thisspeed.fullLoadPower * speedRatio;
} else {
OpModePower = thisspeed.fullLoadPower * thisspeed.RTF;
}
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@rraustad rraustad Mar 5, 2026

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So either multiply by PLR when NOT including startup losses or use RTF when including startup losses. That does seem correct. And only do this for speeds > 1 because at low speed the compressor will obviously cycle on and off. To save me some investigation time, why is line 424 different (i.e., doesn't check for speedNum)?

OpModeWasteHeat = thisspeed.fullLoadWasteHeat * thisspeed.RTF;

if ((speedNum > 1) && (speedRatio < 1.0) && !singleMode) {
Expand Down Expand Up @@ -411,7 +421,11 @@ void CoilCoolingDXCurveFitOperatingMode::CalcOperatingMode(EnergyPlus::EnergyPlu
inletNode.MassFlowRate;
outletNode.Temp = Psychrometrics::PsyTdbFnHW(outletNode.Enthalpy, outletNode.HumRat);

this->OpModePower += (1.0 - thisspeed.RTF) * lowerspeed.fullLoadPower;
if (!this->applyPartLoadFractionAllSpeeds) {
this->OpModePower += (1.0 - speedRatio) * lowerspeed.fullLoadPower;
} else {
this->OpModePower += (1.0 - thisspeed.RTF) * lowerspeed.fullLoadPower;
}
this->OpModeWasteHeat += (1.0 - thisspeed.RTF) * lowerspeed.fullLoadWasteHeat;
this->OpModeRTF = 1.0; // if we are on greater than 1 speed, RTF *must* be 1
}
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2 changes: 2 additions & 0 deletions src/EnergyPlus/Coils/CoilCoolingDXCurveFitOperatingMode.hh
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Expand Up @@ -70,6 +70,7 @@ struct CoilCoolingDXCurveFitOperatingModeInputSpecification
Real64 ratio_of_initial_moisture_evaporation_rate_and_steady_state_latent_capacity = 0.0;
Real64 latent_capacity_time_constant = 0.0;
Real64 nominal_time_for_condensate_removal_to_begin = 0.0;
std::string apply_part_load_fraction_to_speeds_greater_than_1;
std::string apply_latent_degradation_to_speeds_greater_than_1;
std::string condenser_type;
Real64 nominal_evap_condenser_pump_power = 0.0;
Expand Down Expand Up @@ -114,6 +115,7 @@ struct CoilCoolingDXCurveFitOperatingMode
Real64 maxCyclingRate = 0.0;
Real64 latentTimeConst = 0.0;
bool latentDegradationActive = false;
bool applyPartLoadFractionAllSpeeds = true;
bool applyLatentDegradationAllSpeeds = false;

// results from coil model at speed
Expand Down
6 changes: 6 additions & 0 deletions src/Transition/InputRulesFiles/Rules25-2-0-to-26-1-0.md
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Expand Up @@ -24,6 +24,12 @@ See pull request [#11366](https://github.com/NatLabRockies/EnergyPlus/pull/11366

# Object Change: ObjectStartsWithC

# Object Change: Coil:Cooling:DX:CurveFit:OperatingMode

Insert new field A2 which is also TODO, "Apply Part Load Fraction to Speeds Greater than 1", defaulted to blank
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@rraustad rraustad Mar 5, 2026

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Isn't this TODONE?


See pull request TODO.

# Object Change: ObjectStartsWithD

# Object Change: ObjectStartsWithE
Expand Down
1 change: 1 addition & 0 deletions testfiles/5Zone_Unitary_VSDesuperheater.idf
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Expand Up @@ -2812,6 +2812,7 @@
0.0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
0.0, !- Latent Capacity Time Constant {s}
0.0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
No, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down
1 change: 1 addition & 0 deletions testfiles/CoilWaterDesuperheatingUnitaryCoilDX.idf
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Expand Up @@ -1502,6 +1502,7 @@
, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
, !- Latent Capacity Time Constant {s}
, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
, !- Apply Latent Degradation to Speeds Greater than 1
, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down
1 change: 1 addition & 0 deletions testfiles/DXCoilSystemAuto.idf
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Expand Up @@ -1744,6 +1744,7 @@
, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
, !- Latent Capacity Time Constant {s}
, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
, !- Apply Latent Degradation to Speeds Greater than 1
, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down
5 changes: 5 additions & 0 deletions testfiles/EMSLoadBasedMultiSpeedDXCoilOverrideControl.idf
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Expand Up @@ -2532,6 +2532,7 @@
0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
0, !- Latent Capacity Time Constant {s}
0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
No, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down Expand Up @@ -2991,6 +2992,7 @@
0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
0, !- Latent Capacity Time Constant {s}
0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
No, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down Expand Up @@ -3460,6 +3462,7 @@
0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
0, !- Latent Capacity Time Constant {s}
0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
No, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down Expand Up @@ -4116,6 +4119,7 @@
0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
0, !- Latent Capacity Time Constant {s}
0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
No, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down Expand Up @@ -4772,6 +4776,7 @@
0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
0, !- Latent Capacity Time Constant {s}
0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
No, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down
1 change: 1 addition & 0 deletions testfiles/EMSSetpointBasedMultiSpeedDXCoilOverrideControl.idf
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Expand Up @@ -2945,6 +2945,7 @@
0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
0, !- Latent Capacity Time Constant {s}
0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
No, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down
1 change: 1 addition & 0 deletions testfiles/FurnaceWithDXSystem_CoolingHXAssisted_NewDXCoil.idf
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Expand Up @@ -1493,6 +1493,7 @@
, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
, !- Latent Capacity Time Constant {s}
, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
, !- Apply Latent Degradation to Speeds Greater than 1
, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down
1 change: 1 addition & 0 deletions testfiles/HeatPump-ACCA-Sizing_UnitarySystem_HeatPumpAuto.idf
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Expand Up @@ -1759,6 +1759,7 @@
, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
, !- Latent Capacity Time Constant {s}
, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
, !- Apply Latent Degradation to Speeds Greater than 1
, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down
5 changes: 5 additions & 0 deletions testfiles/PythonPluginLoadBasedMultiSpeedDXCoilOverrideControl.idf
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Expand Up @@ -2532,6 +2532,7 @@
0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
0, !- Latent Capacity Time Constant {s}
0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
No, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down Expand Up @@ -2991,6 +2992,7 @@
0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
0, !- Latent Capacity Time Constant {s}
0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
No, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down Expand Up @@ -3460,6 +3462,7 @@
0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
0, !- Latent Capacity Time Constant {s}
0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
No, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down Expand Up @@ -4116,6 +4119,7 @@
0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
0, !- Latent Capacity Time Constant {s}
0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
No, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down Expand Up @@ -4772,6 +4776,7 @@
0, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
0, !- Latent Capacity Time Constant {s}
0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
No, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down
1 change: 1 addition & 0 deletions testfiles/UnitarySystem_DXCoilSystemAuto.idf
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Expand Up @@ -1771,6 +1771,7 @@
, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
, !- Latent Capacity Time Constant {s}
, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
, !- Apply Latent Degradation to Speeds Greater than 1
, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down
1 change: 1 addition & 0 deletions testfiles/UnitarySystem_FurnaceWithDXSystemRHcontrol.idf
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Expand Up @@ -1359,6 +1359,7 @@
0.4, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
45, !- Latent Capacity Time Constant {s}
1000, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
, !- Apply Latent Degradation to Speeds Greater than 1
, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down
1 change: 1 addition & 0 deletions testfiles/UnitarySystem_HeatPumpAuto.idf
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Expand Up @@ -1741,6 +1741,7 @@
, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
, !- Latent Capacity Time Constant {s}
, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
, !- Apply Latent Degradation to Speeds Greater than 1
, !- Condenser Type
, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down
1 change: 1 addition & 0 deletions testfiles/UnitarySystem_MultiSpeedCoils_SingleMode.idf
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Expand Up @@ -2162,6 +2162,7 @@
1.5, !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
45.0, !- Latent Capacity Time Constant {s}
1000.0, !- Nominal Time for Condensate Removal to Begin {s}
, !- Apply Part Load Fraction to Speeds Greater than 1
No, !- Apply Latent Degradation to Speeds Greater than 1
AirCooled, !- Condenser Type
100, !- Nominal Evaporative Condenser Pump Power {W}
Expand Down
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