Air source heat pump system: The winter heat pump uses refrigerant as the heat medium, which absorbs heat energy in the air (indirect heat exchange in the evaporator), and uses the compressor to transfer the low temperature heat energy to high temperature heat energy, then heats the system to circulate water (indirect heat transfer in the condenser). The summer heat pump uses refrigerant as the cold medium, which absorbs the cold in the air (indirect heat exchange in the condenser), and uses the compressor to reduce the heat energy at high temperature to the low temperature cold energy, then circulate water in the refrigeration system (indirect heat transfer in the evaporator).