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

openstudio-standards/lib/openstudio-standards/prototypes/common/objects/Prototype.FanConstantVolume.rb

Lines 31 to 52 in 4c2b381

	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)
	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.")

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]

openstudio-standards/lib/openstudio-standards/prototypes/common/objects/Prototype.hvac_systems.rb

Lines 2169 to 2173 in 4c2b381

	# create terminal fan
	# @type [OpenStudio::Model::FanConstantVolume] pfp_fan
	pfp_fan = create_fan_by_name(model,
	'PFP_Fan',
	fan_name: "#{zone.name} PFP Term Fan")

openstudio-standards/lib/openstudio-standards/prototypes/common/objects/Prototype.Fan.rb

Lines 147 to 158 in 4c2b381

	fan_json = get_fan_from_standards(standards_name: standards_name)
	case fan_json['type']
	when 'ConstantVolume'
	create_fan_constant_volume_from_json(model,
	fan_json,
	fan_name: fan_name,
	fan_efficiency: fan_efficiency,
	pressure_rise: pressure_rise,
	motor_efficiency: motor_efficiency,
	motor_in_airstream_fraction: motor_in_airstream_fraction,
	end_use_subcategory: end_use_subcategory)

The JSON in question:

openstudio-standards/lib/openstudio-standards/standards/ashrae_90_1/data/ashrae_90_1.fans.json

Lines 135 to 146 in 4c2b381

	{
	"name": "PFP_Fan",
	"type": "ConstantVolume",
	"pressure_rise": 1.20439,
	"fan_efficiency": null,
	"motor_efficiency": null,
	"motor_in_airstream_fraction": 1.0,
	"fan_power_minimum_flow_rate_fraction": null,
	"fan_power_minimum_flow_rate_input_method": null,
	"fan_curve": null,
	"notes": null
	},

openstudio-standards/lib/openstudio-standards/prototypes/common/objects/Prototype.FanConstantVolume.rb

Lines 128 to 155 in 4c2b381

	def create_fan_constant_volume_from_json(model,
	fan_json,
	fan_name: nil,
	fan_efficiency: nil,
	pressure_rise: nil,
	motor_efficiency: nil,
	motor_in_airstream_fraction: nil,
	end_use_subcategory: nil)
	# check values to use
	fan_efficiency ||= fan_json['fan_efficiency']
	pressure_rise ||= fan_json['pressure_rise']
	motor_efficiency ||= fan_json['motor_efficiency']
	motor_in_airstream_fraction ||= fan_json['motor_in_airstream_fraction']
	end_use_subcategory ||= fan_json['end_use_subcategory']
	# convert values
	pressure_rise = pressure_rise ? OpenStudio.convert(pressure_rise, 'inH_{2}O', 'Pa').get : nil
	# create fan
	fan = create_fan_constant_volume(model,
	fan_name: fan_name,
	fan_efficiency: fan_efficiency,
	pressure_rise: pressure_rise,
	motor_efficiency: motor_efficiency,
	motor_in_airstream_fraction: motor_in_airstream_fraction,
	end_use_subcategory: end_use_subcategory)
	return fan
	end

[jmarrec]

openstudio-standards/lib/openstudio-standards/prototypes/common/objects/Prototype.FanConstantVolume.rb

Lines 31 to 52 in 4c2b381

	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)
	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.")

    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.")