An air source heat pump is an energy-saving device that utilizes high-level energy to flow heat from a low-level heat source to a high-level heat source. As the low-level heat source of the heat pump, air is inexhaustible, available everywhere, and can be obtained free of charge. Moreover, the installation and use of air source heat pumps are relatively convenient. The current products include household heat pump air conditioners, commercial unit heat pump air conditioners and heat pump cold and hot water units.