Thanks Slugbaby it was the ch thermistor, fixed it.
the boiler is known as Sime Halstead Combi.Its a mixture of Sime and Halstead parts.
Many thanks,
Norm.
Hi,
I have a Wickes Combi 30/90 which is a Sime Combi Halstead.
When the central heating is on the Rads. get hotter and hotter, the boiler switches off but lights up all most immediately it continues out of control untill I switch it off.I have no room stats just the control on the boiler...