Where does refrigerant boil in a heat pump system?

In a heat pump system, the refrigerant boils in the evaporator. This component is where the refrigerant absorbs heat from the environment, typically from the indoor air during heating mode or from the outdoor air in cooling mode. As the refrigerant flows through the evaporator coil, it undergoes a phase change from a liquid to a gas, which occurs because it absorbs heat.

This process of boiling is essential for the heat pump's operation, as it allows the system to gather and transfer heat efficiently. The energy absorbed by the boiling refrigerant is what ultimately contributes to heating or cooling the space. The other components of the heat pump, such as the condenser, compressor, and expansion valve, have different functions. The condenser is where the refrigerant releases heat and condenses back into a liquid, the compressor increases the pressure of the refrigerant gas, and the expansion valve regulates the flow of refrigerant into the evaporator but does not facilitate boiling itself.