Adding a solenoid valve ahead of my float valves

[Sequoia]

Long ago, it was suggested to add a 24V solenoid valve ahead of each of the float valves (soap and rinse) that are served by a 1" copper line. These valves would only allow water flow IF a bay (any bay) were turned on-- so a failed float valve would not flood things and lead to a huge water bill.

I have a couple of questions-- is it better to used normally CLOSED or normally OPEN valve? And, if I need to have the valve open up on a signal from ANY bay (normally closed), how can I wire that up without accidentally jumpering the 24V from all of the bays together, which I don't want to do?

Finally, do I need to take precautions on my pumps so they will not burn up should they be running while somehow the incoming water supply is shut off? If so, how do you manage that?

 

[helpfuljames]

Finally, do I need to take precautions on my pumps so they will not burn up should they be running while somehow the incoming water supply is shut off? If so, how do you manage that?

The float valve already has enough flow to keep up with the pump needs, so the momentary absence of flow should not be an issue. If your solenoid fails (shut) then all the bays are doomed, however.

I cannot help you with the electrical, sorry.

 

[MEP001]

I would use relays for the task. I've started replacing multiplexers with a small bank of Omron relays at about $7 per bay. They never fail with such a low current being switched. I'd recommend a separate 24V source for the solenoid, then just connect your motor starter to the relay and each relay's output can go straight to the solenoid.

I would use a normally closed solenoid. Operationally they are the same. Unless you're concerned about a transformer failure or someone tripping over a wire, there's no reason to keep the coil energized most of the time - it might even lead to early failure.

For a low-water safety, a second relay (SPDT) with the bay's power run through the closed circuit and a float switch in the tank to send power on drop. If the water level gets too low it would power those relays, opening the circuit and killing all 24V power to the bays. This sort of safety is actually a good idea for any car wash.

For what it's worth, I've used only Watermaster float valves and have never had one fail wide open. At worst it would begin to leak slowly and overfill the tank after 10 or so minutes of being idle. They tend to last about 2 years with no maintenance.