Supplementary Boiler Controls for EIR AWHP

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Hi all,

I'm seeking clarification on how EnergyPlus models the HeatPump:PlantLoop:EIR:Heating object when a supplementary boiler is also part of the system. Specifically, I want to understand the sequence of operations:

• When does the supplementary boiler activate in relation to the heat pump operation, particularly after the EIR compressor shuts down at the lockout temperature?

• Should I assume that the compressor ramps down as it approaches the Minimum Source Inlet Temerature, and at that point, EnergyPlus transitions to using the supplementary boiler to meet the remaining heating load?

• If the above assumption is incorrect, what is the recommended way to model this behavior? Would I need to implement an AvailabilityManager:LowTemperatureTurnOn or use EMS to manage the switch-over to the supplementary boiler?

I found an EnergyPlus example file with that scenario - called PlantLoopHeatPump_EIR_LargeOffice-2-AWHP-AuxBoiler-Pri-Sec-4PipeBeam.idf - which includes a similar setup. However, the model doesn't explicitly include controls for switching to the supplementary boiler, leaving me unsure about how this transition is handled internally in EnergyPlus.

Any insights or suggestions on how to properly model and control this scenario would be greatly appreciated. Thank you! Thanks!