diff --git a/VectoCommon/VectoCommon/BusAuxiliaries/ISSMDeclarationInputs.cs b/VectoCommon/VectoCommon/BusAuxiliaries/ISSMDeclarationInputs.cs
index f38ab1e7611420243f5f411006a2d76a001d518e..e6397e677ec3bf1dbb6898c20bca19680817e9e6 100644
--- a/VectoCommon/VectoCommon/BusAuxiliaries/ISSMDeclarationInputs.cs
+++ b/VectoCommon/VectoCommon/BusAuxiliaries/ISSMDeclarationInputs.cs
@@ -194,6 +194,9 @@ namespace TUGraz.VectoCommon.BusAuxiliaries
 
 	public enum HeatPumpType
 	{
+		[GuiLabel("not applicable")]
+		not_applicable,
+
 		[GuiLabel("None")]
 		none,
 
@@ -216,6 +219,7 @@ namespace TUGraz.VectoCommon.BusAuxiliaries
 	public static class HeatPumpTypeHelper
 	{
 		private const string NONE = "none";
+		private const string NOT_APPLICABLE = "not applicable";
 		private const string R_744 = "R-744";
 		private const string NON_R_744_2_STAGE = "non R-744 2-stage";
 		private const string NON_R_744_3_STAGE = "non R-744 3-stage";
@@ -227,12 +231,13 @@ namespace TUGraz.VectoCommon.BusAuxiliaries
 			switch (parse)
 			{
 				case NONE: return HeatPumpType.none;
+				case NOT_APPLICABLE: return HeatPumpType.not_applicable;
 				case R_744: return HeatPumpType.R_744;
 				case NON_R_744_2_STAGE: return HeatPumpType.non_R_744_2_stage;
 				case NON_R_744_3_STAGE: return HeatPumpType.non_R_744_3_stage;
 				case NON_R_744_4_STAGE: return HeatPumpType.non_R_744_4_stage;
 				case NON_R_744_CONTINUOUS: return HeatPumpType.non_R_744_continuous;
-				// to support old input parametersd
+				// to support old input parameters
 				case "2-stage": return HeatPumpType.non_R_744_2_stage;
 				case "3-stage": return HeatPumpType.non_R_744_3_stage;
 				case "4-stage": return HeatPumpType.non_R_744_4_stage;
@@ -247,6 +252,7 @@ namespace TUGraz.VectoCommon.BusAuxiliaries
 			}
 			switch (type) {
 				case HeatPumpType.none: return NONE;
+				case HeatPumpType.not_applicable: return NOT_APPLICABLE;
 				case HeatPumpType.R_744: return R_744;
 				case HeatPumpType.non_R_744_2_stage: return NON_R_744_2_STAGE;
 				case HeatPumpType.non_R_744_3_stage: return NON_R_744_3_STAGE;