| 摘要 |
PURPOSE:To meet an unexpected need for hot water at midnight by a method wherein an electric current is supplied to an auxiliary heater for heating only the upper part of water, in preference to a main heater for heating the whole of the water. CONSTITUTION:When a midnight power supply time zone sets in, a relay 22 is operated to turn a contact 221 on (a) side to close a contact 231 so that only the auxiliary heater 3 arranged in the upper part of the hot water tank is energized to heat the upper part of the water. When the upper part of the water reaches a predetermined temperature, a thermostat 20 above the hot water tank is opened to interrupt the flow of electric current to the relay 22 whereupon the contact 221 is turned on (b) side to interrupt the electric current to the auxiliary heater 3 and a relay 24 is energized through a thermostat 21 below the hot water tank with the result that a contact 241 is closed and only the main heater 2 arranged in the lower part of the hot water boiler is energized. |
