Morning,
I have a conventional CH system with room and hot water thermostats and a Drayton Mid Position valve, which I recall replacing a good few years ago. The boiler is not firing when there is demand from the room stat but it does when there is demand from the water stat. I think the circuit board in the MPV is faulty, possibly what appears to be a relay. The synchron motor works and the water valve operates. Grateful for any thoughts.
TVMIA
"CS" wrote
Are there limit switches in the valve which need to "make" for the boiler to fire? Not sure whether the MPVs have these, may depend on manufacturer and system wiring.
Phil
The synchron motor is faulty. I had the exact same problem a couple of years ago.
Yes, there's a microswitch at the full travel position (which is central heating only). In most circuit arrangements, this microswitch is used to generate the call for heat signal to the boiler. Most likely the microswitch has failed, or the MPV isn't making it all the way across and isn't operating the microswitch.
In message , slider writes
Not necessarily - could be a burned out microswitch
The drayton units are the ones that get rebadged as BG/Celsia etc.
They are available from (Wolseley) Parts Centre (amongst other places).
It might be that the valve is not getting to the CH only end position or the microswitch is fubar.
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