Air to water heat pumps operates on a similar principle to an ordinary refrigerator. Heat from the atmosphere is extracted by an outdoor unit and is absorbed by a refrigerant solution that is then compressed to a high temperature, then the heat that is generated is used by the indoor unit to create hot water for a traditional pressurized heating and hot water system. Greensource air to water heat pumps can provide an outgoing flow temperature of 65ºC. However, they are ideally suited for low-temperature underfloor central heating systems and appropriately sized radiators, as well as for baths and showers, providing a low cost solution throughout the year.