An air-energy heat pump is a water heater that USES the energy in the air to generate heat energy, which is converted to the swimming pool to provide different hot water needs for the home 24 hours a day, and at the same time USES the least amount of energy to meet the water needs. The air energy heat pump works according to the principle of \"reverse Carnot\". The principle of reverse Carnot cycle is that the liquid refrigerant of low temperature and high pressure is changed into the liquid refrigerant of low temperature and low pressure after being throttled by the expansion mechanism, and then enters the air switch to evaporate and absorb the heat in the air for heat exchange.