| 摘要 |
PURPOSE:To detect that a water level is a definite value or less to display the same, by providing a temp. switch having predetermined operational temp. for detecting the water temp. in the communication pipe having a heat insulating structure provided to a container in close vicinity of the bottom part thereof to constitute a combination structure of said switch and a display lamp. CONSTITUTION:A communication pipe 6 is formed by connecting L-shaped pipes 7, 7 respectively comprising heat insulating material to the upper and lower communication holes of an inner container 1 and connecting a heat conductive straight pipe 8 between said L-shaped pipes 7, 7. When the water in the inner container 1 holds a water level A or more before heating, a temp. switch 9 is closed and a display device 11 lights but, after a current is supplied to a heater, water temp. exceeds the operation point of the temp. switch 9 within a short time to put out lights. When several min is further elapsed, the water temp. reaches set temp. When the quantity of water in the inner container 1 is reduced because of the use of hot water to reach the water level A or less, the straight pipe 8 is not contacted with hot water to be cooled rapidly and the temp. thereof becomes lower than the operation point of the temp. switch 9. By this mechanism, the temp. switch 9 is closed and the display device 11 lights to display that the quantity of water in the inner container 1 becomes lower than the water level A.
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