My boiler comes on then cuts off after a few seconds. The fault diagnosis pointed to the thermostat, which I replaced. The problem remained. I discovered that when I remove the thermostat phial from its pocket, the boiler works, but once I replace the phial it doesn't.
Can you help?

Mal F, December 2008

I think it's the thermostat? The heating comes on when it feels like it, on the controls when used manualy the water come on but not the heating. Sometime the wall stat will click and then nothing. I've recently replaced the valve that switches the hot water to the heating and the emersion.

gary c, January 2015

sounds like ur heat exchanger is blocked.your system needs cleaning

a gas man, December 2009