Turning on and off plant components using outdoor ambient temperature

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Hi all,

I am trying to model a hybrid heat pump system in EnergyPlus 9.2, a hybrid heat pump system is essentially an air to water source heat pump that works with a gas condensing boiler used for space heating and domestic heating water. Its operation can vary between heat pump mode, hybrid mode (heat pump and boiler) and boiler only mode depending on the outdoor ambient temperature.

The figure below shows how I have the boiler and heat pump in the SVG within the space heating loop

I was wondering would anyone know how I could turn on and off the boiler and the heat pump depending on the outdoor ambient temperatures to model the hybrid heat pump systems.

For above 3 degrees Celsius I would like heat pump only mode, between 3 and -2 degrees celsius I would like hybrid mode (boiler and heat pump satisfying the heating load) and for below -2 degrees I would like boiler only mode.

I was hoping to use the class PlantEquipmentOperation:OutdoorDryBulb but I think this only works for condenser equipment.

I would really appreciate any advice you all would have on this.

Thanks,

Tadhg.