zone valves and end switches

Derek Brazier

Would someone explain to me why some zone valves have end switches and why are they necessary

Thanks

Alan(CaliforniaRadiant)Forbes

End switches

are extremely useful. Most of the time, you want to turn on a boiler or start a circulator only when the zone valve has opened, so you wire the device through the end switch. Many zone valves take 30 seconds or more to open and you don't want any mechanical action until there's an open path for flow.

You can even wire line voltage (hot leg) through the end switch, but be careful you don't exceed the voltage and amp rating on the end switch; you can find this information out in the zone valve instructions.

Same thing with manifold actuators; some of them have end switches and for those that don't, you have to pipe in a pressure differential by-pass so you don't dead-head the pump against slow opening, wax cartridge actuators.

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