fix: no negative heating demand allowed - that-s cooling...

VectoCore/VectoCore/Models/BusAuxiliaries/DownstreamModules/Impl/HVAC/SSMCalculate.cs

@@ -768,7 +768,7 @@ namespace TUGraz.VectoCore.Models.BusAuxiliaries.DownstreamModules.Impl.HVAC
 							: run2TotalW //.TechListAmendedFuelHeater(env.Temperature, env.Solar)
                     ) - ssmTOOL.EngineWasteHeat;
 			}
-			return result;
+			return VectoMath.Max(result, 0.SI<Watt>());
 
 		}
 	}

VectoCore/VectoCoreTest/Models/Declaration/BusAux/SSMTestHeatingCooling.cs

@@ -1357,9 +1357,9 @@ public class SSMTestHeatingCooling
     [
 		TestCase(CFG1, 1, 5e3, 8475.49374),
 		TestCase(CFG1, 2, 5e3, 2261.98124),
-		TestCase(CFG1, 3, 5e3, -604.51875),
-		TestCase(CFG1, 4, 5e3, -3026.0124),
-		TestCase(CFG1, 5, 5e3, -3505.3468),
+		TestCase(CFG1, 3, 5e3, 0), // no negative heating demand!
+		TestCase(CFG1, 4, 5e3, 0), // no negative heating demand!
+		TestCase(CFG1, 5, 5e3, 0), // no negative heating demand!
 		TestCase(CFG1, 6, 5e3, 0),
 		TestCase(CFG1, 7, 5e3, 0),
 		TestCase(CFG1, 8, 5e3, 0),