diff --git a/src/Ironbug.HVAC/BaseClass/IB_Field.cs b/src/Ironbug.HVAC/BaseClass/IB_Field.cs
index b5d82f79..3ae3ba75 100644
--- a/src/Ironbug.HVAC/BaseClass/IB_Field.cs
+++ b/src/Ironbug.HVAC/BaseClass/IB_Field.cs
@@ -53,6 +53,11 @@ protected IB_Field(IB_Field otherField)
             this.SetterMethod = otherField.SetterMethod;
             this.Description = otherField.Description;
         }
+
+        public IB_Field(string fullName): this(fullName, "")
+        {
+        }
+
         public IB_Field(string fullName, string nickName, Type valueType = default)
         {
 
diff --git a/src/Ironbug.HVAC/BaseClass/IB_ModelObject.cs b/src/Ironbug.HVAC/BaseClass/IB_ModelObject.cs
index fe4854f5..4d5678c8 100644
--- a/src/Ironbug.HVAC/BaseClass/IB_ModelObject.cs
+++ b/src/Ironbug.HVAC/BaseClass/IB_ModelObject.cs
@@ -78,6 +78,7 @@ public IB_ModelObject(ModelObject ghostOpsObj)
         public bool ShouldSerializeCustomActuators() => !this.CustomActuators.IsNullOrEmpty();
         public bool ShouldSerializeIBProperties() => !this.IBProperties.IsNullOrEmpty();
         #endregion
+        public void AddCustomAttribute(string fieldName, object value) => this.SetFieldValue(new IB_Field(fieldName), value);
 
         /// <summary>
         /// Same as SetFieldValue
diff --git a/src/Ironbug.HVAC/LoopObjs/IB_CentralHeatPumpSystemModule.cs b/src/Ironbug.HVAC/LoopObjs/IB_CentralHeatPumpSystemModule.cs
index 68ef6bc8..8ec7efc1 100644
--- a/src/Ironbug.HVAC/LoopObjs/IB_CentralHeatPumpSystemModule.cs
+++ b/src/Ironbug.HVAC/LoopObjs/IB_CentralHeatPumpSystemModule.cs
@@ -14,7 +14,7 @@ public class IB_CentralHeatPumpSystemModule : IB_ModelObject
 
         private IB_ChillerHeaterPerformanceElectricEIR _chiller => this.GetChild<IB_ChillerHeaterPerformanceElectricEIR>();
 
-        public int NumberOfChillerHeaterModules { get => Get<int>(1); private set => Set(value, 1); }
+        //public int NumberOfChillerHeaterModules { get => Get<int>(1); private set => Set(value, 1); }
 
         [JsonConstructor]
         private IB_CentralHeatPumpSystemModule(bool forDeserialization) : base(null)
@@ -38,8 +38,8 @@ public ModelObject ToOS(Model model)
 
             var chillerHeater = this._chiller.ToOS(model) as ChillerHeaterPerformanceElectricEIR;
             newObj.setChillerHeaterModulesPerformanceComponent(chillerHeater);
-            newObj.setNumberofChillerHeaterModules(this.NumberOfChillerHeaterModules);
-            var count = model.getChillerHeaterPerformanceElectricEIRs().Count;
+            //newObj.setNumberofChillerHeaterModules(this.NumberOfChillerHeaterModules);
+            //var count = model.getChillerHeaterPerformanceElectricEIRs().Count;
           
             return newObj;
         }
diff --git a/src/Ironbug.HVAC_Tests/HVACComponentsTest.cs b/src/Ironbug.HVAC_Tests/HVACComponentsTest.cs
index 1b047cd2..3dfce182 100644
--- a/src/Ironbug.HVAC_Tests/HVACComponentsTest.cs
+++ b/src/Ironbug.HVAC_Tests/HVACComponentsTest.cs
@@ -212,5 +212,25 @@ public void IB_ScheduleType()
           
         }
 
+        [Test]
+        public void IB_WaterHeaterHP()
+        {
+
+            var obj = new HVAC.IB_WaterHeaterHeatPump();
+            obj.AddCustomAttribute("InletAirConfiguration", "OutdoorAirOnly");
+            obj.AddCustomAttribute("CompressorLocation", "Outdoors");
+
+            var md1 = new OpenStudio.Model();
+            obj.ToOS(md1);
+
+            var osObj = md1.getWaterHeaterHeatPumps().First();
+            Assert.AreEqual(osObj.inletAirConfiguration(), "OutdoorAirOnly");
+            Assert.AreEqual(osObj.compressorLocation(), "Outdoors");
+
+            string saveFile = GenFileName;
+            var saved = md1.Save(saveFile);
+            Assert.True(saved);
+        }
+
     }
 }