The plate heat exchanger unit is a modular electromechanical device that integrates a heat exchanger, circulating water pump, make-up water pump, water treatment system, temperature sensor, pressure transducer, electric control valve, pressure reducing valve, instruments, electrical control, and pipeline valves. The integrated heat exchanger unit is a standardized heat exchange equipment that converts different thermal conditions into conditions required by users. Secondary water is filtered and decontaminated, then circulates into the heat exchanger and is heated by steam or high-temperature water for heat supply. After entering the plate heat exchanger, the steam or high-temperature water turns into condensate water or high-temperature return water and returns to the heat source, completing the loop circulation of the primary and secondary heating systems. The make-up water pump pumps soft water into the system to maintain constant system pressure. Plate heat exchangers are suitable for heat exchange in various fields such as heating and ventilation, petroleum, chemical, thermoelectric, metallurgy, textile, food, medicine, nuclear industry, shipping, and marine development. They can also be used in civil buildings such as factories, institutions, schools, residential areas, and villas, as well as commercial buildings such as shopping malls, hotels, restaurants, and resorts, for heating, air conditioning, water supply, domestic hot water, swimming pool water in winter, and for preparing industrial production process water. With a wide range of applications, they are highly favored by users.