Fix #1675

src/energyplus/ForwardTranslator.cpp

@@ -3600,6 +3600,12 @@ std::vector<IddObjectType> ForwardTranslator::iddObjectsToTranslateInitializer()
   result.push_back(IddObjectType::OS_Coil_Heating_Water);
   result.push_back(IddObjectType::OS_Coil_Heating_WaterToAirHeatPump_EquationFit);
   result.push_back(IddObjectType::OS_Coil_WaterHeating_Desuperheater);
+
+  // If using a plantLoop, this will be translated by the PlantLoop. But WaterHeaters can also be used stand-alone, so always translate them
+  // We'll check in their FT if the "Peak Use Flow Rate" is actually initialized as it's an indication that the WH was
+  result.push_back(OS_WaterHeater_Mixed);
+  result.push_back(OS_WaterHeater_Stratified);
+
   result.push_back(IddObjectType::OS_Connection);
   result.push_back(IddObjectType::OS_Connector_Mixer);
   result.push_back(IddObjectType::OS_Connector_Splitter);

src/energyplus/ForwardTranslator/ForwardTranslateWaterHeaterMixed.cpp

@@ -58,6 +58,12 @@ boost::optional<IdfObject> ForwardTranslator::translateWaterHeaterMixed( WaterHe
   boost::optional<double> value;
   boost::optional<Schedule> schedule;
 
+  if (!modelObject.plantLoop() && !(modelObject.peakUseFlowRate() && modelObject.useFlowRateFractionSchedule()) ) {
+    LOG(Warn, modelObject.briefDescription() << " will not be translated as it not on a PlantLoop, and it does not have both a Peak Use Flow Rate "
+        "and a Use Flow Rate Fraction Schedule which is a required condition for stand-alone operation");
+    return boost::none;
+  }
+
   IdfObject idfObject(IddObjectType::WaterHeater_Mixed);
 
   m_idfObjects.push_back(idfObject);

src/energyplus/ForwardTranslator/ForwardTranslateWaterHeaterStratified.cpp

@@ -54,6 +54,12 @@ boost::optional<IdfObject> ForwardTranslator::translateWaterHeaterStratified( Wa
   boost::optional<double> value;
   boost::optional<Schedule> schedule;
 
+  if (!modelObject.plantLoop() && !(modelObject.peakUseFlowRate() && modelObject.useFlowRateFractionSchedule()) ) {
+    LOG(Warn, modelObject.briefDescription() << " will not be translated as it not on a PlantLoop, and it does not have both a Peak Use Flow Rate "
+        "and a Use Flow Rate Fraction Schedule which is a required condition for stand-alone operation");
+    return boost::none;
+  }
+
   // Name
   IdfObject idfObject = createRegisterAndNameIdfObject(openstudio::IddObjectType::WaterHeater_Stratified, modelObject);