PURPOSE: To conserve the electric power consumption by a method wherein heatrs are energized only under the condition that the temperature of a water pipe is below the predetermined value and no water runs through said water pipe and as well as drain plugs are closed.
CONSTITUTION: In the waterpipe 1, which is equipped with anti-freezing measures and as well as has a water intake port 2 and a hot water supply port 3, a plurality of the drain plugs 5, at one of which a switch 7 for detecting the opening and closing of the plug 5 is equipped, the heaters 4, a thermoswitch 6 and a running water detecting unit 8 equipped with a flow switch 15 are provided. The switch 15 connects in series together with the switches 6 and 7 to the heaters 4 and links with the combustion controlling unit 18 of a burner 16. Owing to the structure as described above, the heaters 4 are energized only under the condition tht the temperature of the water pipe 1 is below the predetermined value and no water runs through the water pipe 1 and as well as the drain plugs are closed and, because either one of the switches 6, 7 and 15 is open under the condition except the condition as just mentioned above, none of the heaters 4 are energized.
HARASHIMA YUKIKAZU
INOUE MASAICHI
