| 摘要 |
<p>A waterboiler comprises 2 kW and 1 kW heating elements (11, 12 respectively) that together heat the water (2) to about 96 0 G, as sensed by a thermistor (14), whereupon the 2 kW element (11) cuts out and the water (2) is further heated to, and maintained at, water boiling point by the 1 kW element (12). The arrangement lessens the problems of cavitation noise and element scaling associated with prior waterboilers. In an alternative embodiment, the output of a single heating element is modulated by using a transformer to reduce the voltage in put. A water inlet has a solenoid valve (8) controlled by a reed switch (9) actuated by a magnetic float (9'). Another reed switch (10)/magnetic float (10') ensure that the healing elements (11, 12) cannot be energised until they are immersed. <IMAGE></p> |
