Thermostat not controlling temperature

[Andrewd01]

My room thermostat seems to be working but it does not switch the boiler on and off. I have dismantled it and everything looks OK and it switches the connection on and off, but it will not switch the radiators off even when set at zero. They are constantly on. This is a major problem as it now getting towards summer. The boiler control box does not have separate water and heating controls, so when the timer is on I constantly have the radiators on. If I switch off the boiler control then I have no hot water! Anyone got any ideas?

 

[tomy]

test the thermostat with a multimeter to prove that it is knackered . Do you have any motorised valves anywhere that could be the other cause of your problem.

 

[Andrewd01]

Thanks for the information. Just how do I test it?

 

[meldrew's_mate]

... Just how do I test it?...

Well I wouldn't recommend doing so yourself judging by the amount of guidance you have asked for. Limit yourself to testing the functionality of the mechanical devices eg

...Do you have any motorised valves anywhere...?

A motorised valve is a component which will (if fitted to your system) open and close under the control of the thermostat. Find it, then see if it does. If you need pictures look at the top of the forum under "definitions".

 

[ChrisR]

I have dismantled it and everything looks OK and it switches the connection on and off

How did you test it?
You may just have a wire going from the thermostat to the pump. Shouldn't be hard to check, even with a neon screwdriver at a pinch, though a <£10 meter would be better.
Turn everyting off and test for continuity between the thermostat terminals when you turn the temp up and down past the click.