The main engine of JKHN type sanitary heat exchanger developed by Fine Open Energy Company adopts spiral threaded tube heat exchanger with high efficiency, energy saving and low scaling tendency. Besides, the heat exchanger is compact in size and occupies one fifth of the area of other heat exchangers. It can save a lot of capital construction cost and room area of heat exchanger station, heat exchange and water storage in heat exchanger unit. Separate and avoid breeding bacteria. Mature, reliable, stable and maintenance free.