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Combi System Improvements #2190

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Combi System Improvements #2190

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fc89c44
simplify combi logic
Apr 7, 2026
45fd391
Try StorageTank control mode
yzhou601 Apr 14, 2026
2e2385e
Merge branch 'master' of https://github.com/NREL/OpenStudio-HPXML int…
yzhou601 Apr 14, 2026
d70b5c1
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Apr 14, 2026
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8 changes: 4 additions & 4 deletions HPXMLtoOpenStudio/measure.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -3,8 +3,8 @@
<schema_version>3.1</schema_version>
<name>hpxm_lto_openstudio</name>
<uid>b1543b30-9465-45ff-ba04-1d1f85e763bc</uid>
<version_id>bf9d7070-c3d0-4251-ad9d-e45da9629d51</version_id>
<version_modified>2026-04-09T03:47:56Z</version_modified>
<version_id>b2c2fc5a-5062-45bb-85ef-d93fe797f8ab</version_id>
<version_modified>2026-04-07T23:13:47Z</version_modified>
<xml_checksum>D8922A73</xml_checksum>
<class_name>HPXMLtoOpenStudio</class_name>
<display_name>HPXML to OpenStudio Translator</display_name>
Expand Down Expand Up @@ -499,7 +499,7 @@
<filename>output.rb</filename>
<filetype>rb</filetype>
<usage_type>resource</usage_type>
<checksum>2712B090</checksum>
<checksum>7F8E008D</checksum>
</file>
<file>
<filename>psychrometrics.rb</filename>
Expand Down Expand Up @@ -715,7 +715,7 @@
<filename>waterheater.rb</filename>
<filetype>rb</filetype>
<usage_type>resource</usage_type>
<checksum>096F8A5F</checksum>
<checksum>E9274389</checksum>
</file>
<file>
<filename>weather.rb</filename>
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37 changes: 2 additions & 35 deletions HPXMLtoOpenStudio/resources/waterheater.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -317,24 +317,8 @@ def self.apply_combi(runner, model, spaces, hpxml_bldg, hpxml_header, water_heat
unavailable_periods: unavailable_periods,
unit_multiplier: unit_multiplier)
water_heater.setSourceSideDesignFlowRate(100 * unit_multiplier) # set one large number, override by EMS
water_heater.setSourceSideFlowControlMode('StorageTank')

# Create alternate setpoint schedule for source side flow request
alternate_stp_sch = water_heater.setpointTemperatureSchedule.get.clone(model).to_Schedule.get
alternate_stp_sch.setName("#{obj_name_combi} Alt Spt")
water_heater.setIndirectAlternateSetpointTemperatureSchedule(alternate_stp_sch)

# Create setpoint schedule to specify source side temperature
# tank source side inlet temperature, degree C
boiler_spt_mngr = model.getSetpointManagerScheduleds.find { |spt_mngr| spt_mngr.setpointNode.get == boiler_plant_loop.loopTemperatureSetpointNode }
boiler_heating_spt = boiler_spt_mngr.to_SetpointManagerScheduled.get.schedule.to_ScheduleConstant.get.value
source_stp_sch = Model.add_schedule_constant(
model,
name: "#{obj_name_combi} Source Spt",
value: boiler_heating_spt,
limits: EPlus::ScheduleTypeLimitsTemperature
)
# reset dhw boiler setpoint
boiler_spt_mngr.to_SetpointManagerScheduled.get.setSchedule(source_stp_sch)
boiler_plant_loop.autosizeMaximumLoopFlowRate()

# change loop equipment operation scheme to heating load
Expand Down Expand Up @@ -460,9 +444,8 @@ def self.apply_combi_system_EMS(model, water_heating_systems, plantloop_map)
equipment_sch_sensors = {}
equipment_target_temp_sensors = {}
tank_volume, deadband, tank_source_temp = 0.0, 0.0, 0.0
alt_spt_sch = nil
tank_temp_sensor, tank_spt_sensor, tank_loss_energy_sensor = nil, nil, nil
altsch_actuator, pump_actuator = nil, nil
pump_actuator = nil, nil
water_heater = nil

# Create sensors and actuators
Expand Down Expand Up @@ -495,20 +478,6 @@ def self.apply_combi_system_EMS(model, water_heating_systems, plantloop_map)
output_var_or_meter_name: 'Schedule Value',
key_name: water_heater.setpointTemperatureSchedule.get.name
)

alt_spt_sch = water_heater.indirectAlternateSetpointTemperatureSchedule.get
if alt_spt_sch.to_ScheduleConstant.is_initialized
comp_type_and_control = EPlus::EMSActuatorScheduleConstantValue
elsif alt_spt_sch.to_ScheduleRuleset.is_initialized
comp_type_and_control = EPlus::EMSActuatorScheduleYearValue
else
comp_type_and_control = EPlus::EMSActuatorScheduleFileValue
end
altsch_actuator = Model.add_ems_actuator(
name: "#{combi_sys_id} AltSchedOverride",
model_object: alt_spt_sch,
comp_type_and_control: comp_type_and_control
)
end
plant_loop.components.each do |c|
next unless c.to_WaterUseConnections.is_initialized
Expand Down Expand Up @@ -597,10 +566,8 @@ def self.apply_combi_system_EMS(model, water_heating_systems, plantloop_map)
combi_ctrl_program.addLine('Set WH_Energy_Heat = WH_Use + WH_Loss - WH_HeatToHighSetpoint')
combi_ctrl_program.addLine('If WH_Energy_Demand > 0')
combi_ctrl_program.addLine("Set #{pump_actuator.name} = WH_Energy_Heat / (Cp * DeltaT * 3600 * ZoneTimeStep)")
combi_ctrl_program.addLine("Set #{altsch_actuator.name} = 100") # Set the alternate setpoint temperature to highest level to ensure maximum source side flow rate
combi_ctrl_program.addLine('Else')
combi_ctrl_program.addLine("Set #{pump_actuator.name} = 0")
combi_ctrl_program.addLine("Set #{altsch_actuator.name} = NULL")
combi_ctrl_program.addLine('EndIf')

# ProgramCallingManagers
Expand Down
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