Air-to-water heat pump: Does defrost load increases total heat load?

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Hello

I am using EIRPlantLoopHeatPump (old version) for modeling an air-to-water heat pump. I noticed that the Q_defrost is not added as a load to the heat pump. In OnDemand:Reverse mode the heat pump should be extracting energy from the loop resulting in increased heating demand from either the heat pump or the supplemental equipment. I checked the source code for this and could not identify how the effect of defrost impacts the load side fluid loop conditions. The heating capacity and input power multipliers only adjusts the unit's delivery and power draw.

Can anybody explain if I am missing out on anything here?

-Abir Ahsan