Prevent division by zero in WAHP heating design day calculations

src/EnergyPlus/WaterToAirHeatPumpSimple.cc

@@ -1240,16 +1240,16 @@ namespace WaterToAirHeatPumpSimple {
         Real64 VolFlowRate;
         Real64 CoolCapAtPeak;                  // Load on the cooling coil at cooling design conditions
         Real64 HeatCapAtPeak;                  // Load on the heating coil at heating design conditions
-        Real64 PeakTotCapTempModFac = 0.0;     // Peak total cooling capacity curve modifier
-        Real64 RatedTotCapTempModFac = 0.0;    // Rated total cooling capacity curve modifier
-        Real64 PeakHeatCapTempModFac = 0.0;    // Peak heating capacity curve modifier
+        Real64 PeakTotCapTempModFac = 1.0;     // Peak total cooling capacity curve modifier
+        Real64 RatedTotCapTempModFac = 1.0;    // Rated total cooling capacity curve modifier
+        Real64 PeakHeatCapTempModFac = 1.0;    // Peak heating capacity curve modifier
         Real64 DesignEntWaterTemp;             // Design entering coil water temperature
         Real64 SensCapAtPeak;                  // Sensible load on the cooling coil at cooling design conditions
-        Real64 PeakSensCapTempModFac = 0.0;    // Peak sensible cooling capacity curve modifier
-        Real64 RatedSensCapTempModFac = 0.0;   // Rated sensible cooling capacity curve modifier
-        Real64 RatedHeatCapTempModFac = 0.0;   // Rated heating capacity curve modifier
-        Real64 RatedCoolPowerTempModFac = 0.0; // Rated cooling power curve modifier
-        Real64 RatedHeatPowerTempModFac = 0.0; // Rated heating power curve modifier
+        Real64 PeakSensCapTempModFac = 1.0;    // Peak sensible cooling capacity curve modifier
+        Real64 RatedSensCapTempModFac = 1.0;   // Rated sensible cooling capacity curve modifier
+        Real64 RatedHeatCapTempModFac = 1.0;   // Rated heating capacity curve modifier
+        Real64 RatedCoolPowerTempModFac = 1.0; // Rated cooling power curve modifier
+        Real64 RatedHeatPowerTempModFac = 1.0; // Rated heating power curve modifier
         Real64 RatedCapCoolTotalDesCDD;        // Rated total cooling coil capacity determined at cooling design conditions
         constexpr Real64 Tref(283.15);         // Refrence Temperature for performance curves,10C [K]
         int TimeStepNumAtMax;

tst/EnergyPlus/unit/WaterToAirHeatPumpSimple.unit.cc

@@ -1547,7 +1547,7 @@ TEST_F(EnergyPlusFixture, WaterToAirHeatPumpSimpleTest_SizeHVACWaterToAirRatedCo
     state->dataWaterToAirHeatPumpSimple->SimpleWatertoAirHP(2).RatioRatedHeatRatedTotCoolCap = 1.23;
 
     state->dataSize->FinalZoneSizing(state->dataSize->CurZoneEqNum).DesCoolVolFlow = 0.20;
-    state->dataSize->FinalZoneSizing(state->dataSize->CurZoneEqNum).DesHeatVolFlow = 0.0;
+    state->dataSize->FinalZoneSizing(state->dataSize->CurZoneEqNum).DesHeatVolFlow = 0.0004;
     state->dataSize->FinalZoneSizing(state->dataSize->CurZoneEqNum).CoolDesTemp = 13.0;
     state->dataSize->FinalZoneSizing(state->dataSize->CurZoneEqNum).HeatDesTemp = 40;
     state->dataSize->FinalZoneSizing(state->dataSize->CurZoneEqNum).CoolDesHumRat = 0.0075;