Continuous flow electric heater - has first heating unit and additional second unit for increased heating power

摘要

The switch for the first heating unit is operated by a switching device responding to a pressure difference produced by water flow. The second heating unit is switched through a relay whose winding is energised through a pushbutton contact. It has a holding contact in parallel with the above. Current is supplied to these two contacts through a further contact controlled by water flow through the heater. It is closed only when a specified water flow is reached. The additional contact is a micro switch, which can also be operated by the switching device when the specified water flow is reached.