To provide a space heating, hot-water supplying or snow thawing system for a highly heat insulated and highly airtight housing, healthy, comfortable, safe, energy saving and economic with low-temperature heating operation by using a heat storage electric boiler device utilizing midnight electric power for performing space heating and hot-water supply in the highly insulated and highly airtight housing.

A heating system uses a heating panel heater for heating the housing with low-temperature radiation heat by circulating hot water warmed by utilizing midnight electric power and stored in a heat storage tank in a circuit having a three-way valve through a pipe. A hot-water system is provided with a heat exchanger at a predetermined position in a hot-water circulation passage, through which city water is supplied to be immediately warmed by the heat of the hot water in the heat storage tank and then supplied to each supply source. The space heating system and the hot-water system are integrated to form a completely sealed system. Thus, one heat source is used to perform space heating, hot-water supply and snow thawing, efficiently utilizing the thermal energy in the highly heat insulated and highly airtight housing.