When operating in heating mode, what is the role of the outdoor coil in a heat pump?

In heating mode, the outdoor coil in a heat pump serves as a condenser. This is a vital process in how heat pumps operate. When the heat pump is running in heating mode, it extracts heat from the outside air, even in cold conditions, and transfers that heat indoors.

The refrigerant flows through the outdoor coil, where it absorbs heat from the ambient air, causing it to evaporate and transition into a gas. However, in heating mode, once the refrigerant reaches the compressor, it is compressed to a high pressure, and when it moves to the outdoor coil, it releases that heat to the indoor space as it condenses back into a liquid. Therefore, in this cycle, the outdoor coil acts as the final stage where heat is released, thus functioning as the condenser in this heating process.

This understanding is crucial because it highlights how heat pumps can efficiently transfer heat in both heating and cooling modes, relying on the transformation of refrigerant properties and the role of coils in the system.