| 摘要 |
PURPOSE:To enable to heat water, prevent from heating with no water and retain heat by a structure wherein a heating circuit and a heat retaining circuit, both of which act based upon the temperature detection signals issued from a temperature detecting circuit, are equipped. CONSTITUTION:A temperature detecting element 17 is connected to a temperature detecting circuit 20. Water is poured in a vessel 2 and both a main heater 13 and a heat retaining heater 14 are energized. When the temperature detection signal representing about 95 deg.C is outputted from the temperature detecting circuit 20, the energizing to the heat retaining heater 14 is cut-off. When the temperature of steam rises to about 85 deg.C, the energizing to the main heater 13 is cut-off. After that, when the temperature detection signal representing about 95 deg.C is outputted from the temperature detecting circuit 20 as the result of lowering of water temperature, the heat retaining heater 14 is energized on and off in order to retain heat. When cold water is added in the vessel 2 and consequently the temperature detection signal representing about 90 deg.C or lower is outputted from the temperature detecting circuit 20, the main heater 13 is energized again. If the vessel is heated with no water therein, the temperature of the vessel rises quickly to about 105 deg.C or above, resulting in instantly cutting off the energizing to the main heater 13 and to the heat retaining heater 14. |
