DIY Doctor

Thermostat not working

Postby soundant » Sun Sep 26, 2010 3:15 pm

Hi - my hallway thermostat (satchwell) is not switching off my kitchen wall mount boiler (Concord WRS).

My choice of settings on the boiler is WATER ONLY or WATER AND HEATING (plus off, once twice and a manual timer wheel).

My hot water has never worked (I use the immersion heater) and I believe the motorised valve by the HWC is open with the motor removed. Same for the valve by the boiler.

Can anyone explain what could be wrong - I tried disconnecting the live from the thermostat and the boiler still works - does this mean the thermostat could be OK but the boiler is still trying to heat the HWC - I am guessing that the boiler tries to heat the HW first and when thatis hot it looks at the CH stat next? Or something like this?

Thanks guys for any help.
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Simply Build It

Postby stoneyboy » Wed Sep 29, 2010 9:45 pm

If your motorised valves are in the open position they will always be calling for heat from the boiler unless the controller is in the off position.
Start by getting the MVs working correctly.
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Postby sparx » Thu Sep 30, 2010 6:11 pm

As stoneyboy says, the boiler is 'called' on & off by micro switches inside the 'head' of the motorised valve.
The tank & room 'stats tell the water which way to go and when in relevant positions the switches then call for heat.
The M/V is key to everything!
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