heat pump 
Device exchanging heat between two environments of different temperatures; it can either heat or cool a house, depending on how the circuit is set.
Device compressing the refrigerant to the desired pressure.
Propeller-shaped blades drawing in outdoor air (heating mode) or expelling indoor air (cooling mode).
Mechanism automatically cutting off the power supply in the event of overload.
Part of the pump in which, depending on the setting, the outside air is tapped (heating mode) or the indoor air is cooled (cooling mode).