I have a Glow-worm Micron 50 boiler. If the thermostat is set to 20 it clicks on and off all day, but if you need to up the temperature it then doesnt click off. So the rads just get hotter and hotter. We've replaced the thermostat and the mid position actuator.
Does anyone know so I dont get ripped off, and keep replacing items , then it still doesnt work. Thanks.

Annie, January 2007

I hate to say this but it sounds like a case of operator error; has your engineer explained your system?

Where is the room stat located? You may be better off going for an upgrade and having thermostatic TRV's fitted... If the room temperature is being maintained at 20 deg when set to 20 deg; then the system is fine.

If you turn it to 21 deg and the room exceeds 21 deg; it can only be the room stat as you proved the rest of the system at the 20 deg stage of things.



If you are turning the stat to 30 deg; then it will stay on pretty much forever as the system will need to work double time to get the house heated to that temperature.

Remember; the room thermostat only monitors the room that it is fitted in and even then; it's only looking at the air that is directly surrounding it.

It will turn off when the air surrounding it hits the desired temperature; but other rooms may seem incredibly hot in the meantime... Hence why TRV's were invented.

GasAid.co.uk, January 2007