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