Condensing units are familiar temperature-control devices in refrigerators, air conditioners, heat pumps and chillers. They move energy in the form of heat by compressing a gas known as a “refrigerant,” then pumping it through a system of coils and using the air around the coils to heat and cool spaces. Electronic controls, fans, pumps and coils manage the condenser’s work.

Condensers apply pressure to gas until it becomes a liquid–forcing energy out as heat–and then circulate the cooled liquid through a closed system, where it absorbs heat as it returns to the compressor.