| 摘要 |
<p>A heater for liquid comprises a vessel (10) having an inlet (20) for cold liquid and an outlet (18) for hot liquid, an electrically operated valve means (22) to control the flow of liquid into the vessel (10) through the inlet (20), and a heating means (12) to heat the liquid in the vessel (10), first control means (C1) operative for controlling the liquid level in the vessel (10), the first control means (C1) comprising a level sensor (28) to which the first control means (C1) responds by maintaining the electrically operated valve means (22) closed when the level of liquid in the vessel (10) reaches an upper limit, the heater having a second control means (C2) operable independently from the first control means (C1), the second control means (C2) including a temperature sensor (29) to which the second control means (C2) responds by rendering the heating means (12) operative when a temperature below a first threshold temperature is sensed, and inoperative when a temperature above a second threshold temperature is sensed. <IMAGE></p> |
