In the heating system with heat pump, the water tank can store cold or heat, and can improve system stability and usability. It is specially designed for air source heat pumps, which can effectively reduce the starting frequency of the device, prolong the service life of the unit, and save electricity. Prevent clogging of the system. Automatically releases air from the system, protects the outdoor unit from overpressure, and reduces cavitation of the pump impeller.