In an earlier contribution to this discussion,
Jerry. wrote:

"Set Square" wrote in message
...
snip

It is far more likely that your lack of flow is due to problems with
the pump. How is this wired - is it simply wired in parallel with
the boiler or is it connected to the boiler's pump-over-run
connection? --

Yes the pump is connected via a pump-over-run connection. It's
looking like a defective sensor on the boiler, there is no electrical
feed to pump.

I starting to suspect this / might / have been the (intermittent)
fault since the boiler was first installed and not the three position
valve.......

Thanks to all for the replies.


You *have* got a permanent live feed to the boiler in addition to the
switched live, haven't you? Without this, the pump won't over-run - but it
will still run when the switched live (coming from the programmer and/or
room stat) is on.
--
Cheers,
Set Square
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