Merge pull request #868 from NREL/split-combi-system

Two boiler approach for combi system

Changelog.md

@@ -10,6 +10,7 @@ __New Features__
 - The `WaterFixturesUsageMultiplier` input now also applies to general water use internal gains and recirculation pump energy (for some control types).
 - Relaxes requirement for `ConditionedFloorAreaServed` for air distribution systems; now only needed if duct surface areas not provided.
 - **Breaking change**: Each `VentilationFan` must have one (and only one) `UsedFor...` element set to true.
+- Updates combi boiler model to be simpler, faster, and more robust by using separate space/water heating plant loops and boilers.
 - BuildResidentialHPXML measure:
   - **Breaking change**: Changes the zip code argument name to `site_zip_code`.
   - Adds support for ambient foundations for single-family attached and apartment units.

HPXMLtoOpenStudio/measure.xml

@@ -3,8 +3,8 @@
   <schema_version>3.0</schema_version>
   <name>hpxm_lto_openstudio</name>
   <uid>b1543b30-9465-45ff-ba04-1d1f85e763bc</uid>
-  <version_id>56a21f99-cfb8-488b-8783-2177a1cdc4e2</version_id>
-  <version_modified>20220411T223247Z</version_modified>
+  <version_id>2a19d7d9-f4a4-4b5b-b8db-ba93dcdaa3d3</version_id>
+  <version_modified>20220415T140250Z</version_modified>
   <xml_checksum>D8922A73</xml_checksum>
   <class_name>HPXMLtoOpenStudio</class_name>
   <display_name>HPXML to OpenStudio Translator</display_name>
@@ -169,12 +169,6 @@
       <usage_type>resource</usage_type>
       <checksum>BF53D293</checksum>
     </file>
-    <file>
-      <filename>test_water_heater.rb</filename>
-      <filetype>rb</filetype>
-      <usage_type>test</usage_type>
-      <checksum>B415B698</checksum>
-    </file>
     <file>
       <filename>test_lighting.rb</filename>
       <filetype>rb</filetype>
@@ -433,12 +427,6 @@
       <usage_type>resource</usage_type>
       <checksum>8ABCD77B</checksum>
     </file>
-    <file>
-      <filename>waterheater.rb</filename>
-      <filetype>rb</filetype>
-      <usage_type>resource</usage_type>
-      <checksum>9C3C60BB</checksum>
-    </file>
     <file>
       <filename>geometry.rb</filename>
       <filetype>rb</filetype>
@@ -510,12 +498,6 @@
       <usage_type>resource</usage_type>
       <checksum>9EB9D0AE</checksum>
     </file>
-    <file>
-      <filename>constants.rb</filename>
-      <filetype>rb</filetype>
-      <usage_type>resource</usage_type>
-      <checksum>BCE31C4F</checksum>
-    </file>
     <file>
       <filename>meta_measure.rb</filename>
       <filetype>rb</filetype>
@@ -528,5 +510,23 @@
       <usage_type>resource</usage_type>
       <checksum>FF182243</checksum>
     </file>
+    <file>
+      <filename>test_water_heater.rb</filename>
+      <filetype>rb</filetype>
+      <usage_type>test</usage_type>
+      <checksum>E955AF3A</checksum>
+    </file>
+    <file>
+      <filename>constants.rb</filename>
+      <filetype>rb</filetype>
+      <usage_type>resource</usage_type>
+      <checksum>FA749B6E</checksum>
+    </file>
+    <file>
+      <filename>waterheater.rb</filename>
+      <filetype>rb</filetype>
+      <usage_type>resource</usage_type>
+      <checksum>3B95C662</checksum>
+    </file>
   </files>
 </measure>

HPXMLtoOpenStudio/resources/constants.rb

@@ -166,14 +166,6 @@ def self.ObjectNameClothesDryerExhaust
     return 'clothes dryer exhaust'
   end
 
-  def self.ObjectNameCombiWaterHeatingEnergy(water_heater_name)
-    return "#{water_heater_name} dhw energy"
-  end
-
-  def self.ObjectNameCombiSpaceHeatingEnergy(water_heater_name)
-    return "#{water_heater_name} htg energy"
-  end
-
   def self.ObjectNameComponentLoadsProgram
     return 'component loads program'
   end

HPXMLtoOpenStudio/resources/waterheater.rb

@@ -136,12 +136,13 @@ def self.apply_heatpump(model, runner, loc_space, loc_schedule, weather, water_h
 
   def self.apply_combi(model, runner, loc_space, loc_schedule, water_heating_system, ec_adj, solar_thermal_system)
     solar_fraction = get_water_heater_solar_fraction(water_heating_system, solar_thermal_system)
+
     boiler, boiler_plant_loop = get_combi_boiler_and_plant_loop(model, water_heating_system.related_hvac_idref)
+    boiler.setName('combi boiler')
+    boiler.additionalProperties.setFeature('HPXML_ID', water_heating_system.id) # Used by reporting measure
     boiler.additionalProperties.setFeature('IsCombiBoiler', true) # Used by reporting measure
 
     obj_name_combi = Constants.ObjectNameWaterHeater
-    convlim = model.getConvergenceLimits
-    convlim.setMinimumPlantIterations(3) # add one more minimum plant iteration to achieve better energy balance across plant loops.
 
     if water_heating_system.water_heater_type == HPXML::WaterHeaterTypeCombiStorage
       if water_heating_system.standby_loss <= 0
@@ -188,50 +189,32 @@ def self.apply_combi(model, runner, loc_space, loc_schedule, water_heating_syste
     alternate_stp_sch.setValue(alt_temp)
     new_heater.setIndirectAlternateSetpointTemperatureSchedule(alternate_stp_sch)
 
-    # Create hx setpoint schedule to specify source side temperature
-    hx_stp_sch = OpenStudio::Model::ScheduleConstant.new(model)
-    hx_stp_sch.setName("#{obj_name_combi} HX Spt")
+    # Create setpoint schedule to specify source side temperature
+    source_stp_sch = OpenStudio::Model::ScheduleConstant.new(model)
+    source_stp_sch.setName("#{obj_name_combi} Source Spt")
     boiler_spt_mngr = model.getSetpointManagerScheduleds.select { |spt_mngr| spt_mngr.setpointNode.get == boiler_plant_loop.loopTemperatureSetpointNode }[0]
-    boiler_spt = boiler_spt_mngr.to_SetpointManagerScheduled.get.schedule.to_ScheduleConstant.get.value
-    hx_temp = (UnitConversions.convert(water_heating_system.temperature, 'F', 'C') + deadband(water_heating_system.water_heater_type) / 2.0 + boiler_spt) / 2.0 # tank source side inlet temperature, degree C
-    hx_stp_sch.setValue(hx_temp)
+    boiler_heating_spt = boiler_spt_mngr.to_SetpointManagerScheduled.get.schedule.to_ScheduleConstant.get.value
+    # tank source side inlet temperature, degree C
+    source_stp_sch.setValue(boiler_heating_spt)
+    # 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
     scheme_dhw = OpenStudio::Model::PlantEquipmentOperationHeatingLoad.new(model)
     scheme_dhw.addEquipment(1000000000, new_heater)
     loop.setPrimaryPlantEquipmentOperationScheme(scheme_dhw)
 
-    # Create loop for source side
-    source_loop = create_new_loop(model, 'dhw source loop', hx_temp)
-    source_loop.autosizeMaximumLoopFlowRate()
-
-    # Create heat exchanger
-    combi_hx = create_new_hx(model, Constants.ObjectNameTankHX)
-
-    # Add heat exchanger to the load distribution scheme
+    # Add dhw boiler to the load distribution scheme
     scheme = OpenStudio::Model::PlantEquipmentOperationHeatingLoad.new(model)
-    scheme.addEquipment(1000000000, combi_hx)
-    source_loop.setPrimaryPlantEquipmentOperationScheme(scheme)
-
-    # Add components to the tank source side plant loop
-    source_loop.addSupplyBranchForComponent(combi_hx)
-
-    new_pump = create_new_pump(model)
-    new_pump.autosizeRatedFlowRate()
-    new_pump.addToNode(source_loop.supplyInletNode)
-
-    new_source_manager = OpenStudio::Model::SetpointManagerScheduled.new(model, hx_stp_sch)
-    new_source_manager.addToNode(source_loop.supplyOutletNode)
-
-    source_loop.addDemandBranchForComponent(new_heater)
-
-    # Add heat exchanger to boiler loop
-    boiler_plant_loop.addDemandBranchForComponent(combi_hx)
+    scheme.addEquipment(1000000000, boiler)
+    boiler_plant_loop.setPrimaryPlantEquipmentOperationScheme(scheme)
+    boiler_plant_loop.addDemandBranchForComponent(new_heater)
     boiler_plant_loop.setPlantLoopVolume(0.001) # Cannot be auto-calculated because of large default tank source side mfr(set to be overwritten by EMS)
 
     loop.addSupplyBranchForComponent(new_heater)
 
-    add_ec_adj(model, new_heater, ec_adj, loc_space, water_heating_system, boiler, combi_hx)
+    add_ec_adj(model, new_heater, ec_adj, loc_space, water_heating_system, boiler)
 
     return loop
   end
@@ -979,16 +962,27 @@ def self.add_hpwh_control_program(model, obj_name_hpwh, amb_temp_sensor, hpwh_bo
 
   def self.get_combi_boiler_and_plant_loop(model, heating_source_id)
     # Search for the right boiler OS object
-    boiler = nil
-    plant_loop = nil
+    boiler_hw = nil
+    plant_loop_hw = nil
     model.getBoilerHotWaters.each do |bhw|
       sys_id = bhw.additionalProperties.getFeatureAsString('HPXML_ID')
-      if sys_id.is_initialized && sys_id.get == heating_source_id
-        boiler = bhw
-        plant_loop = boiler.plantLoop.get
+      next unless sys_id.is_initialized && sys_id.get == heating_source_id
+
+      plant_loop = bhw.plantLoop.get
+      plant_loop_hw = plant_loop.clone(model).to_PlantLoop.get
+
+      # set pump power for water heating to zero
+      plant_loop_hw.supplyComponents.each do |comp|
+        if comp.to_BoilerHotWater.is_initialized
+          boiler_hw = comp.to_BoilerHotWater.get
+        end
+        next unless comp.to_PumpVariableSpeed.is_initialized
+
+        pump_hw = comp.to_PumpVariableSpeed.get
+        pump_hw.setRatedPowerConsumption(0.0)
       end
     end
-    return boiler, plant_loop
+    return boiler_hw, plant_loop_hw
   end
 
   def self.get_desuperheatercoil(water_heating_system, model)
@@ -1231,7 +1225,7 @@ def self.get_default_num_bathrooms(num_beds)
     num_baths = num_beds / 2.0 + 0.5
   end
 
-  def self.add_ec_adj(model, heater, ec_adj, loc_space, water_heating_system, combi_boiler = nil, combi_hx = nil)
+  def self.add_ec_adj(model, heater, ec_adj, loc_space, water_heating_system, combi_boiler = nil)
     adjustment = ec_adj - 1.0
 
     if loc_space.nil? # WH is not in a zone, set the other equipment to be in a random space
@@ -1256,12 +1250,6 @@ def self.add_ec_adj(model, heater, ec_adj, loc_space, water_heating_system, comb
 
     # Sensors
     if [HPXML::WaterHeaterTypeCombiStorage, HPXML::WaterHeaterTypeCombiTankless].include? water_heating_system.water_heater_type
-      ec_adj_sensor_hx = OpenStudio::Model::EnergyManagementSystemSensor.new(model, 'Fluid Heat Exchanger Heat Transfer Energy')
-      ec_adj_sensor_hx.setName("#{combi_hx.name} energy")
-      ec_adj_sensor_hx.setKeyName(combi_hx.name.to_s)
-      ec_adj_sensor_boiler_heating = OpenStudio::Model::EnergyManagementSystemSensor.new(model, 'Boiler Heating Energy')
-      ec_adj_sensor_boiler_heating.setName("#{combi_boiler.name} heating energy")
-      ec_adj_sensor_boiler_heating.setKeyName(combi_boiler.name.to_s)
       ec_adj_sensor_boiler = OpenStudio::Model::EnergyManagementSystemSensor.new(model, "Boiler #{EPlus.fuel_type(fuel_type)} Rate")
       ec_adj_sensor_boiler.setName("#{combi_boiler.name} energy")
       ec_adj_sensor_boiler.setKeyName(combi_boiler.name.to_s)
@@ -1295,15 +1283,9 @@ def self.add_ec_adj(model, heater, ec_adj, loc_space, water_heating_system, comb
     ec_adj_program.setName("#{heater.name} EC_adj")
     if [HPXML::WaterHeaterTypeCombiStorage, HPXML::WaterHeaterTypeCombiTankless].include? water_heating_system.water_heater_type
       ec_adj_program.addLine("Set dhw_e_cons = #{ec_adj_oncyc_sensor.name} + #{ec_adj_offcyc_sensor.name}")
-      ec_adj_program.addLine('Set htg_e_cons = dhw_e_cons')
-      ec_adj_program.addLine("If #{ec_adj_sensor_boiler_heating.name} > 0")
-      ec_adj_program.addLine("  Set dhw_frac = (@Abs #{ec_adj_sensor_hx.name} / #{ec_adj_sensor_boiler_heating.name})")
-      ec_adj_program.addLine('  Set dhw_frac = (@Min dhw_frac 1)')
-      ec_adj_program.addLine("  Set dhw_e_cons = dhw_e_cons + dhw_frac * #{ec_adj_sensor_boiler.name}")
-      ec_adj_program.addLine("  Set htg_e_cons = htg_e_cons + (1.0 - dhw_frac) * #{ec_adj_sensor_boiler.name}")
+      ec_adj_program.addLine("If #{ec_adj_sensor_boiler.name} > 0")
+      ec_adj_program.addLine("  Set dhw_e_cons = dhw_e_cons + #{ec_adj_sensor_boiler.name}")
       ec_adj_program.addLine('EndIf')
-      ec_adj_program.addLine('Set boiler_dhw_energy = dhw_e_cons * 3600 * SystemTimeStep')
-      ec_adj_program.addLine('Set boiler_htg_energy = htg_e_cons * 3600 * SystemTimeStep')
     elsif water_heating_system.water_heater_type == HPXML::WaterHeaterTypeHeatPump
       ec_adj_program.addLine("Set dhw_e_cons = #{ec_adj_sensor.name} + #{ec_adj_oncyc_sensor.name} + #{ec_adj_offcyc_sensor.name} + #{ec_adj_hp_sensor.name} + #{ec_adj_fan_sensor.name}")
     else
@@ -1327,30 +1309,6 @@ def self.add_ec_adj(model, heater, ec_adj, loc_space, water_heating_system, comb
     ec_adj_output_var.setUnits('J')
     ec_adj_output_var.additionalProperties.setFeature('FuelType', EPlus.fuel_type(fuel_type)) # Used by reporting measure
     ec_adj_output_var.additionalProperties.setFeature('HPXML_ID', water_heating_system.id) # Used by reporting measure
-
-    if [HPXML::WaterHeaterTypeCombiStorage, HPXML::WaterHeaterTypeCombiTankless].include? water_heating_system.water_heater_type
-      # EMS Output Variables for combi dhw energy reporting (before EC_adj is applied)
-
-      # DHW energy use:
-      boiler_dhw_output_var = OpenStudio::Model::EnergyManagementSystemOutputVariable.new(model, 'boiler_dhw_energy')
-      boiler_dhw_output_var.setName("#{Constants.ObjectNameCombiWaterHeatingEnergy(heater.name)} outvar")
-      boiler_dhw_output_var.setTypeOfDataInVariable('Summed')
-      boiler_dhw_output_var.setUpdateFrequency('SystemTimestep')
-      boiler_dhw_output_var.setEMSProgramOrSubroutineName(ec_adj_program)
-      boiler_dhw_output_var.setUnits('J')
-      boiler_dhw_output_var.additionalProperties.setFeature('FuelType', EPlus.fuel_type(fuel_type)) # Used by reporting measure
-      boiler_dhw_output_var.additionalProperties.setFeature('HPXML_ID', water_heating_system.id) # Used by reporting measure
-
-      # Space heating energy use:
-      boiler_htg_output_var = OpenStudio::Model::EnergyManagementSystemOutputVariable.new(model, 'boiler_htg_energy')
-      boiler_htg_output_var.setName("#{Constants.ObjectNameCombiSpaceHeatingEnergy(heater.name)} outvar")
-      boiler_htg_output_var.setTypeOfDataInVariable('Summed')
-      boiler_htg_output_var.setUpdateFrequency('SystemTimestep')
-      boiler_htg_output_var.setEMSProgramOrSubroutineName(ec_adj_program)
-      boiler_htg_output_var.setUnits('J')
-      boiler_htg_output_var.additionalProperties.setFeature('FuelType', EPlus.fuel_type(fuel_type)) # Used by reporting measure
-      boiler_htg_output_var.additionalProperties.setFeature('HPXML_ID', water_heating_system.related_hvac_system.id) # Used by reporting measure
-    end
   end
 
   def self.get_default_hot_water_temperature(eri_version)

HPXMLtoOpenStudio/tests/test_water_heater.rb

@@ -885,25 +885,14 @@ def test_tank_indirect
     assert_in_epsilon(t_set, wh.setpointTemperatureSchedule.get.to_ScheduleConstant.get.value, 0.001)
     assert_equal(1.0, wh.offCycleLossFractiontoThermalZone)
 
-    # Heat exchanger
-    assert_equal(1, model.getHeatExchangerFluidToFluids.size)
-    hx = model.getHeatExchangerFluidToFluids[0]
-    hx_attached_to_boiler = false
-    hx_attached_to_tank = false
+    tank_attached_to_boiler = false
     model.getPlantLoops.each do |plant_loop|
-      next if plant_loop.demandComponents.select { |comp| comp == hx }.empty?
-      next if plant_loop.supplyComponents.select { |comp| comp.name.get.include? 'boiler' }.empty?
-
-      hx_attached_to_boiler = true
-    end
-    model.getPlantLoops.each do |plant_loop|
-      next if plant_loop.supplyComponents.select { |comp| comp == hx }.empty?
       next if plant_loop.demandComponents.select { |comp| comp == wh }.empty?
+      next if plant_loop.supplyComponents.select { |comp| comp.name.get.include? 'boiler' }.empty?
 
-      hx_attached_to_tank = true
+      tank_attached_to_boiler = true
     end
-    assert_equal(hx_attached_to_boiler, true)
-    assert_equal(hx_attached_to_tank, true)
+    assert_equal(tank_attached_to_boiler, true)
   end
 
   def test_tank_combi_tankless
@@ -933,25 +922,14 @@ def test_tank_combi_tankless
     assert_in_epsilon(t_set, wh.setpointTemperatureSchedule.get.to_ScheduleConstant.get.value, 0.001)
     assert_equal(1.0, wh.offCycleLossFractiontoThermalZone)
 
-    # Heat exchanger
-    assert_equal(1, model.getHeatExchangerFluidToFluids.size)
-    hx = model.getHeatExchangerFluidToFluids[0]
-    hx_attached_to_boiler = false
-    hx_attached_to_tank = false
+    tank_attached_to_boiler = false
     model.getPlantLoops.each do |plant_loop|
-      next if plant_loop.demandComponents.select { |comp| comp == hx }.empty?
-      next if plant_loop.supplyComponents.select { |comp| comp.name.get.include? 'boiler' }.empty?
-
-      hx_attached_to_boiler = true
-    end
-    model.getPlantLoops.each do |plant_loop|
-      next if plant_loop.supplyComponents.select { |comp| comp == hx }.empty?
       next if plant_loop.demandComponents.select { |comp| comp == wh }.empty?
+      next if plant_loop.supplyComponents.select { |comp| comp.name.get.include? 'boiler' }.empty?
 
-      hx_attached_to_tank = true
+      tank_attached_to_boiler = true
     end
-    assert_equal(hx_attached_to_boiler, true)
-    assert_equal(hx_attached_to_tank, true)
+    assert_equal(tank_attached_to_boiler, true)
   end
 
   def test_tank_heat_pump

ReportSimulationOutput/measure.rb

@@ -2315,6 +2315,9 @@ def get_object_output_variables_by_key(model, object, class_name)
           else
             return { [to_ft[fuel], EUT::HeatingHeatPumpBackup] => ["Boiler #{fuel} Energy"] }
           end
+        else
+          fuel = object.to_BoilerHotWater.get.fuelType
+          return { [to_ft[fuel], EUT::HotWater] => ["Boiler #{fuel} Energy"] }
         end
 
       elsif object.to_CoilCoolingDXSingleSpeed.is_initialized || object.to_CoilCoolingDXMultiSpeed.is_initialized
@@ -2433,12 +2436,6 @@ def get_object_output_variables_by_key(model, object, class_name)
         elsif object.name.to_s.include? Constants.ObjectNameWaterHeaterAdjustment(nil)
           fuel = object.additionalProperties.getFeatureAsString('FuelType').get
           return { [to_ft[fuel], EUT::HotWater] => [object.name.to_s] }
-        elsif object.name.to_s.include? Constants.ObjectNameCombiWaterHeatingEnergy(nil)
-          fuel = object.additionalProperties.getFeatureAsString('FuelType').get
-          return { [to_ft[fuel], EUT::HotWater] => [object.name.to_s] }
-        elsif object.name.to_s.include? Constants.ObjectNameCombiSpaceHeatingEnergy(nil)
-          fuel = object.additionalProperties.getFeatureAsString('FuelType').get
-          return { [to_ft[fuel], EUT::Heating] => [object.name.to_s] }
         else
           return { ems: [object.name.to_s] }
         end

ReportSimulationOutput/measure.xml

@@ -3,8 +3,8 @@
   <schema_version>3.0</schema_version>
   <name>report_simulation_output</name>
   <uid>df9d170c-c21a-4130-866d-0d46b06073fd</uid>
-  <version_id>45301192-6a9e-49bf-8995-6f5d4e36372a</version_id>
-  <version_modified>20220408T155840Z</version_modified>
+  <version_id>9d5b0a6b-ef2b-441b-944f-8f071d46b4ec</version_id>
+  <version_modified>20220413T231147Z</version_modified>
   <xml_checksum>9BF1E6AC</xml_checksum>
   <class_name>ReportSimulationOutput</class_name>
   <display_name>HPXML Simulation Output Report</display_name>
@@ -1588,7 +1588,7 @@
       <filename>measure.rb</filename>
       <filetype>rb</filetype>
       <usage_type>script</usage_type>
-      <checksum>A52FB9B7</checksum>
+      <checksum>3316272E</checksum>
     </file>
   </files>
 </measure>