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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.
compressor
Device compressing the refrigerant to the desired pressure.
fan
Propeller-shaped blades drawing in outdoor air (heating mode) or expelling indoor air (cooling mode).
refrigerant tubing
circuit breaker
Mechanism automatically cutting off the power supply in the event of overload.
outdoor unit
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).
