The heating and cooling capacity, and therefore the heat transfer, are a function of the load and source temperatures and air/water flow rate "ratios". Check that the performance curves used actually change the performance curve output if air flow is different from rated conditions.

    HeatCapRated = SimpleWatertoAirHP(HPNum).RatedCapHeat;

    QLoadTotal = HeatCapRated *
        CurveValue(state, SimpleWatertoAirHP(HPNum).HeatCapCurveIndex, state.dataWaterToAirHeatPumpSimple->SimpleWatertoAirHP(HPNum).HeatCapCurveIndex, ratioTDB, ratioTS, ratioVL, ratioVS);

The heating and cooling capacity, and therefore the heat transfer, are a function of the load and source temperatures and air/water flow rate "ratios". Check that the performance curves used actually change the performance curve output if air flow is different from rated conditions.

    HeatCapRated = SimpleWatertoAirHP(HPNum).RatedCapHeat;

    QLoadTotal = HeatCapRated *
        CurveValue(state, state.dataWaterToAirHeatPumpSimple->SimpleWatertoAirHP(HPNum).HeatCapCurveIndex, ratioTDB, ratioTS, ratioVL, ratioVS);