Changed a radiator to my system so drained down and replaced, when I filled the system back up and fired the boiler all ok. A few minutes later the boiler tripped off we reset and this happened 5/6 times. We realised the water pump had locked and the boiler was over heating so we freed up the pump and the boiler worked again but now the boiler is tripping off and we have to reset it. The water pump is working so I am wondering do you think the thermostat is knackered on the boiler?

Mark, February 2008

Hi, have you managed to find a solution to your problem? I drained my system last night and now it won't work!!

I don't have a header tank in the loft but the cylinder in the airing cupboard does have a little tank at the top which is full.

To drain the system, i turned off the mains to the house.. drained everything, turned the mains back on and i've no water in the radiators. Bled them this morning and 3 of radiators are now full of water but the rest don't have air or water coming out of them.

When i turn the Heating on.. it fires up fine, the pump starts going and after about 30 seconds, the boiler has a fit and shuts off then the pump starts making funny noises.

I've turned everything off and unplugged the pump to stop it dying.. i keep bleeding the radiators but nothing is coming out yet (apart from the 3 with water in them).. anyone got any idea's? It's an old system.. a glow worm ultimate boiler and no pressure guages so i assume it's not pressurised.

Mark, February 2008

I was told this by a mate of mine but all rads are getting hot plus I have bled all rads and no air is coming out. I also tried to crack open a joint on the cylinder but didnt get any air out.

Mark, February 2008

your system is airlocked so the hot water from the boiler isnt circulating and the boiler stat is reaching temp and cutting the boiler out. if you want to verify this, next time the boiler cuts out, feel the pipes above the boiler and one will be too hot to touch. if was working b4 u drained it down its unlikely that a component is broken.

carl, February 2008