update calculate_fan_power_from_curve

NREL · Jan 3, 2025 · 5bdc554 · 5bdc554
1 parent f317c36
commit 5bdc554
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Showing 2 changed files with 12 additions and 8 deletions.
diff --git a/HPXMLtoOpenStudio/measure.xml b/HPXMLtoOpenStudio/measure.xml
@@ -3,8 +3,8 @@
   <schema_version>3.1</schema_version>
   <name>hpxm_lto_openstudio</name>
   <uid>b1543b30-9465-45ff-ba04-1d1f85e763bc</uid>
-  <version_id>a2189a9a-21c5-4d53-a3e8-2a4fc2139304</version_id>
-  <version_modified>2025-01-03T20:21:37Z</version_modified>
+  <version_id>7fcc111a-b955-4915-915b-1782dd485bf7</version_id>
+  <version_modified>2025-01-03T20:32:45Z</version_modified>
   <xml_checksum>D8922A73</xml_checksum>
   <class_name>HPXMLtoOpenStudio</class_name>
   <display_name>HPXML to OpenStudio Translator</display_name>
@@ -387,7 +387,7 @@
       <filename>hvac.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>F5FE260C</checksum>
+      <checksum>A5094D87</checksum>
     </file>
     <file>
       <filename>hvac_sizing.rb</filename>

diff --git a/HPXMLtoOpenStudio/resources/hvac.rb b/HPXMLtoOpenStudio/resources/hvac.rb
@@ -2539,13 +2539,17 @@ def self.create_supply_fan(model, obj_name, fan_watts_per_cfm, fan_cfms, hvac_sy
   # @param hvac_system [HPXML::HeatingSystem or HPXML::CoolingSystem or HPXML::HeatPump] The HPXML HVAC system of interest
   # @return [Double] Fan power at any speed or mode
   def self.calculate_fan_power_from_curve(max_fan_power, fan_ratio, hvac_system)
-    if hvac_system.fan_motor_type == HPXML::HVACFanMotorTypeBPM
+    if hvac_system.fan_motor_type.nil?
+      # For system types that fan_motor_type is not specified, the fan_ratio should be 1
+      fail 'Missing fan motor type for systems where more than one speed is modeled' unless fan_ratio == 1.0
+
+      fan_power = max_fan_power
+    elsif hvac_system.fan_motor_type == HPXML::HVACFanMotorTypeBPM
       # BPM fan
-      index = hvac_system.distribution_system_idref.nil? ? 3 : 2.75
-      fan_power = max_fan_power * (fan_ratio**index)
+      pow = hvac_system.distribution_system_idref.nil? ? 3 : 2.75
+      fan_power = max_fan_power * (fan_ratio**pow)
     else
-      # PSC fan or fan_motor_type = nil
-      # For system types that fan_motor_type is not specified, the fan_ratio is 1 and either equation is fine.
+      # PSC fan
       fan_power = max_fan_power * fan_ratio * (0.3 * fan_ratio + 0.7)
     end
     return fan_power