Boiler cutting out after 5 mins CH, but water only works fine. All rads have been bled although 1 is off for redecorating.

From your discription it sounds like your boiler is providing hot water to sinks, but when the central heating is switched on it shuts down after 5mins. Are your radiators providing any heat at all? If not I suspect pump failure. The boiler will have a thermal cut out. If the boiler is in CH mode boiler will firer up and run, However if the pump is not circulating the hot water provided, water becomes hotter and hotter. Then the thermal cut detects its over heating and shuts the boiler down. Check if the pipe from the pump is getting hot. Not locally to boiler as it will be hot from radiated heat, about a meter away. If pipe is cold pumps not circulating the heated water. Regards Alan

if it is a pressurised system it will need re pressurising ..if its a header tank and cylinder system its probably your pump.

To diagnose this fault i would need to be there,various readings need to be taken but it is possible if the radiator you turned off is piped wrong it could cause this , but i would have thought the boiler would run only 2 mins in that case,if that! Put the job on my builder

has the preassure dropped out, there should be a gauge on the boiler, the preassure should be around 2 bars or in the green zone.