I am using AirLoopHVAC:UnitarySystem to model an air-source heat pump with hot-gas reheat. I'm using DX coils for heating and cooling, and then a Coil:Heating:Desuperheater coil for hot gas reheat. The issue is that when the outdoor air temperature gets below the limit for the DX heating coil operation, the system is not able to provide heat. The actual unit I'm trying to model has a gas heating coil in addition to hot gas reheat. What is the best way to model this? I can put a Coil:Heating:Fuel after the UnitarySystem, but because the fan is integrated into the UnitarySystem, I'm not sure that the fan will operate properly when the UnitarySystem is not able to provide heat but the Coil:Heating:Fuel can.
Question-and-Answer Resource for the Building Energy Modeling Community
