Absorption heat pumps use an ammonia-h2o absorption cycle, as an alternative to a vapor-compression cycle, to transfer heat. Ammonia would be the refrigerant, and water is the absorber. The ammonia condenses at among the list of program’s coils to release heat and evaporates at one other coil to absorb heat. https://purethermal.co.uk/media-news/can-gas-absorption-heat-pumps-provide-an-alternative-heat-pump-option-in-2025/