Glowworm swiftflow 100 boiler. I have replaced the PCB and the DHW side is now working fine but when the CH is switched on the burner stays on no longer than 40 mins from cold. Less if it has recently been on. The gas valve just shuts off completely. It also doesn't look as if the burner is modulating even on DHW when the flow from tap is adjusted.
Any ideas before I start replacing CH thermister? etc
Any ideas before I start replacing CH thermister? etc