What does the "defrost cycle" in heat pumps accomplish?

The defrost cycle in heat pumps is essential for maintaining optimal performance, especially during colder months when frost can accumulate on the outdoor coil. Frost build-up on the outdoor coil can significantly hinder the heat pump's ability to extract heat from the outside air. The defrost cycle temporarily reverses the flow of refrigerant, allowing the outdoor coil to heat up and melt any frost present. This process ensures that the heat pump can continue to operate efficiently, maintaining its ability to provide heating to the indoor space.

While improving heat output, enhancing compressor efficiency, or impacting the indoor coil may seem relevant, the primary purpose of the defrost cycle specifically targets the removal of frost from the outdoor coil as a critical function of maintaining effective heat pump operation. Without this cycle, the heat pump's efficiency would diminish over time, leading to reduced heating capabilities.