Split type, vertical water tank, inner and outer wall of stainless steel SUS-304, insulation layer of foamed imported polyamine. Heat collector is of latest configuration of transverse run, which is of reasonable structure and without scale formation and sediment. It has large volume and high heat efficiency, suits to users of large consumption of hot water or users of storied use in villas. It might be either in mode of natural circulation or in mode of compulsory circulation with automatic water supply equipped with microprocessor to perform automatic management.