| 摘要 |
PURPOSE:To automatically shut-off the flow of gas to a main burner when the water pressure in a heat exchanger rises abnormally due to the occurrence of no water burning and, in addition, open the water passage in the connecting pipe of a feed water pipe when said water pressure rises further even after the stoppage of combustion so as to release the pressure outsise and consequently to prevent the heat exchanger and the water passage from being damaged by a structure wherein a piston with a spring is assembled in the mouth of connecting pipe of the feed water pipe. CONSTITUTION:When no water burning occurs, the water pressure in a heat exchanger rises. As a result, the water pressure applied on a piston 16 also rises, resulting in moving the piston 16 downwards against the force of a spring 18. Consequently, a rod 17 also moves downwards, resulting in turning ON a shut-off valve actuating switch 15 so as to close a shut-off valve 11 through an electronic control device 12 in order to stop the flow of gas and accordingly stop the combustion. When said pressure is applied further more, the piston 16 moves further downwards, resulting in clearing a pressure release port 23 and escaping the pressure outside. Thus, when no water burning occurs, the combustion can be stopped without employing any temperature sensing device, resulting in preventing the heat exchanger and the water passage from being damaged. In addition, high pressure boiling water is prevented from jetting through the pressure release port. |
