Absorption heat pumps use an ammonia-water absorption cycle, as opposed to a vapor-compression cycle, to transfer heat. Ammonia could be the refrigerant, and water could be the absorber. The ammonia condenses at one of several procedure’s coils to release heat and evaporates at one other coil to soak up heat. https://purethermal.co.uk/media-news/can-gas-absorption-heat-pumps-provide-an-alternative-heat-pump-option-in-2025/