In an earlier contribution to this discussion,
Fatboise wrote:

I have 5 motorised valves in my house and want the fifth motorised to
switch on when all four of the other motorised valves switch off, if
one of the four motorised valves is on the fifth motorised valve must
remain closed.

Any suggestions appreciated............I'm thinking of smoe sort of
relay??

It depends on how you are using the valves at present. Most 2-port valves
have a set of volt-free change-over contacts which switch when the valve is
fully open. The COM and NO contacts of these are used in S-Plan systems
(wired in parallel) to switch the boiler and pump on whenever one or more
valves are open.

If you're *not* already using the volt-free contacts for anything else, you
could use them to control your fifth valve. You would have to use the COM
and NC contacts - wired in *series* - to control the motor of your fifth
valve. Then, if *any* of the 4 valves opened, the contact would be broken
and the 5th valve would close.

It takes a finite time for a valve to open or close, of course, so the
status change won't be instant. Does that matter?
--
Cheers,
Set Square
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