PIU (AirTerminalSingleDuctParallelPIUReheat) fans get 0 Pa pressure rise

[jmarrec]

fan_constant_volume_apply_prototype_fan_pressure_rise is checking whether the fan is inside a ZoneHVACComponent, or an airloophvac, or uses 0 otherwise.

A Fan inside a PIU is NEITHER. It nevertheless responds positively to containingHVACComponent

https://github.com/NREL/openstudio-standards/blob/4c2b381058050dfef65dc973fefa6ac65748696a/lib/openstudio-standards/prototypes/common/objects/Prototype.FanConstantVolume.rb#L31-L52

m = Model.new
fan = FanConstantVolume.new(m)
c = CoilHeatingElectric.new(m)
piu = AirTerminalSingleDuctParallelPIUReheat.new(m, m.alwaysOnDiscreteSchedule, fan, c)
raise if fan.containingZoneHVACComponent.is_initialized
raise unless fan.containingHVACComponent.is_initialized

Context:

• Found using create_typical_building_from_model measure from ComStock.

[jmarrec]

I'm guessing other fans have the same issue.

Also please note that the OS SDK is doing something weird with AirLoopHVACUnitarySystem, Most of the time (if not all) components will return a parent AirLoopHVACUNitarySystem in containingHVACComponent, and NOT containingZoneHVACComponent even though AirLoopHVACUnitarySystem IS a ZoneHVACComponent

[jmarrec]

https://github.com/NREL/openstudio-standards/blob/4c2b381058050dfef65dc973fefa6ac65748696a/lib/openstudio-standards/prototypes/common/objects/Prototype.hvac_systems.rb#L2169-L2173

https://github.com/NREL/openstudio-standards/blob/4c2b381058050dfef65dc973fefa6ac65748696a/lib/openstudio-standards/prototypes/common/objects/Prototype.Fan.rb#L147-L158

The JSON in question:
https://github.com/NREL/openstudio-standards/blob/4c2b381058050dfef65dc973fefa6ac65748696a/lib/openstudio-standards/standards/ashrae_90_1/data/ashrae_90_1.fans.json#L135-L146

https://github.com/NREL/openstudio-standards/blob/4c2b381058050dfef65dc973fefa6ac65748696a/lib/openstudio-standards/prototypes/common/objects/Prototype.FanConstantVolume.rb#L128-L155

[jmarrec]

https://github.com/NREL/openstudio-standards/blob/4c2b381058050dfef65dc973fefa6ac65748696a/lib/openstudio-standards/prototypes/common/objects/Prototype.FanConstantVolume.rb#L31-L52

    pressure_rise_in_h2o = 0.0


    # If the fan lives inside of a zone hvac equipment
    if fan_constant_volume.containingZoneHVACComponent.is_initialized
      zone_hvac = fan_constant_volume.containingZoneHVACComponent.get
      if zone_hvac.to_ZoneHVACPackagedTerminalAirConditioner.is_initialized || zone_hvac.to_ZoneHVACFourPipeFanCoil.is_initialized
        pressure_rise_in_h2o = 1.33
      elsif zone_hvac.to_ZoneHVACUnitHeater.is_initialized
        pressure_rise_in_h2o = 0.2
      else # This type of fan should not exist in the prototype models
        return false
      end
    # If the fan lives on an airloop
    elsif fan_constant_volume.airLoopHVAC.is_initialized
      pressure_rise_in_h2o = fan_constant_volume_airloop_fan_pressure_rise(fan_constant_volume)
+   else
+     return false
    end


    # Set the fan pressure rise
    pressure_rise_pa = OpenStudio.convert(pressure_rise_in_h2o, 'inH_{2}O', 'Pa').get
    fan_constant_volume.setPressureRise(pressure_rise_pa)


    OpenStudio.logFree(OpenStudio::Info, 'openstudio.model.FanConstantVolume', "For Prototype: #{fan_constant_volume.name}: #{maximum_flow_rate_cfm.round}cfm; Pressure Rise = #{pressure_rise_in_h2o}in w.c.")