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