| 摘要 |
PURPOSE:To accelerate the operation of an overheating preventive device at the time when the water heater is out of order and to prevent the breakage of heater wires and danger by a method wherein the overheating preventive device is provided at a part which is near the open end of an inlet pipe for introducing cooling water therethrough and which is at a comparatively low temperature in the normal condition. CONSTITUTION:The overheating preventive device 19 is set at an operating temperature at which the device does not operate so long as the water heater is used in the normal condition and is provided near the open end 13a of the inlet pipe 13 on the side of a water incoming chamber A. Therefore, the temperature of the overheating preventive device 19 is kept lower than the temperature of supply hot water even in case the conduction of heat from the vessel of the water heater and the rise in temperature in the water incoming chamber A after closing a valve 12 are taken into consideration, so that it is possible to set the operating temperature of the overheating preventive device 19 at a low value. Accordingly, when the water heater is in an abnormal condition, it is possible to prevent the breakage of wires of the sheath heaters 15 and 16 or danger due to an abnormal temperature rise by detecting the temperature of the upper wall 14b of the vessel 14 immediately and by interrupting the power supply to the water heater. |
