Default new CoilCoolingWaterToAirHeatPumpEquationFit fields in forward translator

[mdahlhausen]

Issue overview

OS 3.7 adds several new fields to the CoilCoolingWaterToAirHeatPumpEquationFit object:

• Part Load Fraction Correlation Curve Name
• Nominal Time for Condensate Removal to Begin {s}
• Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
• Maximum Cycling Rate {cycles/hr}
• Latent Capacity Time Constant {s}
• Fan Delay Time {s}

The defaults are not aligned between OS object creation and the version translator.

Current Behavior

In the forward translator, the defaults for these new fields are different than the defaults used when updating an older .osm using the version translator.
The result is a regression error:

For OS:Coil:Cooling:WaterToAirHeatPump:EquationFit called 'T SW Apartment ZN PSZ-AC Water-to-Air HP Clg Coil 20kBtu/hr 13.0EER'  'Latent Capacity Time Constant': true model = '60.0', compare model = '0.0'
For OS:Coil:Cooling:WaterToAirHeatPump:EquationFit called 'T SW Apartment ZN PSZ-AC Water-to-Air HP Clg Coil 20kBtu/hr 13.0EER'  'Maximum Cycling Rate': true model = '2.5', compare model = '0.0'

Expected Behavior

Either the OS defaults should change, or the version translator should set the new defaults upon translation to avoid regression errors.

Steps to Reproduce

1. Create a model with CoilCoolingWaterToAirHeatPumpEquationFit object in OS 3.6.1
2. Forward translate it with OS develop
3. Create a model with CoilCoolingWaterToAirHeatPumpEquationFit in OS develop
4. compare

Context

impacting openstudio-standards regression tests

[jmarrec]

First, just to clarify:

• Our version translator does the same as the E+ IDFVersionUpdater would do
• Our Ctor defaults these fields to the same as E+ 23.2.0
• The discrepancy you are seeing is because of that. I reported this new discrepancy to the E+ team when I noticed it when working on the upgrade to 23.2.0-IOFreeze, see this table at made at that time:

It seems that:

• These factor were set by the parent object, which defaulted to these values
  • (It's also possible that some of these values were actually not set by the parent object but defaulting to these values internally, something I've been told but I have no confirmed)
• But the default behavior for other coils is to generally zero-out latent degradation...

[jmarrec]

Now:

• I can't touch the VersionTranslator, as this would create a regression. The behavior of a 3.6.1 model should be preserved when updating to 3.7.0
• Thus, there are only two possible paths:
  • Have our SDK Ctor use a different default than E+. I'm not a huge fan of this idea, generally speaking, because it's a bit confusing, but it's maybe fine. (I'm going to prepare a PR that does this, so we have CI running on it and you can test, we can decide if we keep it or trash it)
  • You, on openstudio-standards, set these fields explicitly. @mdahlhausen is that an option? (I don't know what are the side effects of doing this)

---

To be perfectly clear (but add to the confusion), What our VersionTranslator does is actually this:

• If the coil was inside a parent unitary system, basically use the values there or the default of cycling rate=2.5 / latent time = 60.0
• If not, use 0.0 and 0.0 (like the Ctor currently does).

[jmarrec]

For reference:

$ rg -g '*.cpp'  --max-depth 1 "setLatentCapacityTimeConstant\([\d.]+\)"
CoilCoolingDXVariableSpeed.cpp
743:    ok = setLatentCapacityTimeConstant(60.0);
795:    ok = setLatentCapacityTimeConstant(60.0);

CoilCoolingDXCurveFitOperatingMode.cpp
459:    setLatentCapacityTimeConstant(0.0);

CoilCoolingDXSingleSpeed.cpp
960:    setLatentCapacityTimeConstant(0.0);
1000:    setLatentCapacityTimeConstant(0.0);

CoilCoolingDXMultiSpeedStageData.cpp
628:    ok = setLatentCapacityTimeConstant(0.0);
675:    ok = setLatentCapacityTimeConstant(0.0);

CoilPerformanceDXCooling.cpp
590:    setLatentCapacityTimeConstant(45);
614:    setLatentCapacityTimeConstant(45);

CoilCoolingWaterToAirHeatPumpVariableSpeedEquationFit.cpp
520:    ok = setLatentCapacityTimeConstant(0.0);
558:    ok = setLatentCapacityTimeConstant(0.0);

CoilCoolingWaterToAirHeatPumpEquationFit.cpp
594:      ok = setLatentCapacityTimeConstant(0.0);

[mdahlhausen]

Thanks @jmarrec. I can make the openstudio-standards fix.