| 摘要 |
At least two heating power stages can be switched by means of a controller of a hydraulically switched electrical continuous-flow heater. The user can switch on the further heating power stage by opening the tap valve twice. On each occasion when the tap valve 8 is opened, a normally-open contact 10'' of the second heating power stage 3 and a normally-closed contact 10' of a timing element 11 switch over. When the switching contacts 4, 5 close for the first time, the normally-closed contact 10' closes and the normally-open contact 10'' opens, so that, when the switching contacts 4, 5 are closed for the second time, the normally-open contact 10'' closes before a time interval, which is governed by the timing element 11, elapses. <IMAGE>
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