The plate heat exchanger unit is a type of heat exchanger unit, which is characterized by the use of a plate heat exchanger. Under the same pressure loss, the heat transfer coefficient is 3-5 times higher than that tube heat exchanger, and the floor space is One-third of the tubular heat exchanger, the heat recovery rate can be as high as 90% or more. Steam or high-temperature water is fed into the plate heat exchanger unit according to the required flow rate of the heating system under the control of the temperature control valve, The heat exchanger heats the heating (air conditioning) of the hot user back to the water by means of indirect heat exchange, the heated water first flows through the stainless steel core decontamination device, and then enters the heat exchanger through the circulation pump and is heated for use by the user, and is repeated. The primary heat medium returns to the heating pipe network after the heat exchange of the plate heat exchanger unit. The water loss of the system is automatically supplemented by the make-up water pump according to the set pressure to ensure stable and normal operation of the system pressure.