The present invention provides a lower casing of the upper casing and the upper portion of the lower portion is opened to the fiber reinforced plastic tubular open tubular is as contact with a vertical fastening assembly forms a water storage tank in which a certain amount of the water reservoir to the inside of the bottom the casing is a capping for installation assembly to be consistent with the outer perforated the mounting holes on the side of the bottom and a pipe attached to a metal material, the front of the mounting sphere aperture plate, the pipe mount plate has a low water level sensor provided at the upper and the low water level sensor the lower part has one or a plurality of electric heaters for heating the water stored therein is installed through the inside the horizontal direction of the lower casing, and that a lower portion of the electric heater the heated water inside the water storage tank to be supplied for the heating or hot water supply is the water circulation used for the hot water supply pipe and the heating and hot water supply such that the inlet to the water tank Is a circular feeding admission through the hole, and an upper portion of the hot water supply pipe is water storage tank inside portion is bent upward is installed on the accumulated water in the heating process is at an inner upper portion of the lower portion of the pipe mount plate of the water storage the upper end of the tank, tank the vent pipe is installed through to gather discharging the water vapor to the outside in which the vent pipe is prefabricated, it characterized in that the position presented is a portion disposed inside of the water storage tank bending upward the upper end close to the inner upper surface of the upper casing It relates to electric boilers.