HEAT STORAGE TANK FOR SOLAR ENERGY HEATING

A heat storage tank for heating a building and supplying warm water by solar energy is provided to improve efficiency of a boiler system and to reduce beginning time of warm water supply by installing a distributor to circulate returning water according to density and by storing heat first at a defined area. A heat storage tank(14) for heating a building and supplying warm water by solar energy, used in a solar energy heating system(10) including a collecting unit(12) to collect convection heat of the sun and to heat heating medium, and the heat storage tank to store the heating medium heated by the collecting unit and to heat a building and supply warm water, comprises the followings: a first storage heat exchanger(16) and a second storage heat exchanger(20) installed at an upper/lower part respectively of one side of an inside of the storage tank, to heat water in the storage tank by the heating medium; a warm water supply heat exchanger(26) installed at the other side of an inside of the storage tank, to heat supplying water by the water in the storage tank; and a distributor(22) installed in a center of an inside of the storage tank, to improve solar energy storage efficiency by circulating returning water to the storage tank after heating a building to an optimum layer according to density of the water.