The heat exchanger unit is composed of heat exchanger, temperature control valve group, drain valve group (when the heat medium is steam), circulating pump, electric control cabinet, base, pipeline, valve, instrument, etc. It can also be equipped with expansion tank, water treatment equipment, water pump frequency conversion control, temperature control valve, remote communication control, etc., thus forming a complete heat exchange station. The heat exchanger unit has a standardized and modular design, complete configuration, convenient installation, high efficiency and energy saving. The heat exchanger unit has the advantages of compact structure, reliable operation, simple and intuitive operation, and is the first choice for efficient and energy-saving products. This product is suitable for sanitary hot water in residence, office, factory, hospital, hotel, school, etc. The integral heat exchanger unit can be used for both water water exchange and steam water exchange.