"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Malcolm H wrote:

"Set Square" wrote in message
...

I can't see why you'd need a second relay. I drew a circuit diagram
before posting the above, and satisfied myself that, with the single
relay as described, the boiler firing will cause the pump to run but
*not* vice-versa.
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Cheers,
Set Square

Thank you for your reply Set Square. Your solution looks very
elegant to me and I see no reason why it should not work. I propose
to implement it as soon as I can.

Malcolm


Please let us know how you get on!
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Cheers,
Set Square

It's just been pointed out to me that it will be necessary, of course, also
to install a by-pass for the valve which controls the central heating water
flow, otherwise the water will have nowhere to go!!