I have a Glow worm 18 hxi condensing boiler, fitted for 3 years but now it will NOT shut down either after room stat temp has been reached or when the Programmer has stopped calling for Heating ie it would run all day long. This appeared as a problem after I had a bathroom towel rad fitted in lieu of a radiator. My system uses microbore and I did have some problems bleeding it afterwards.
I have checked room stat, tank stat and mid position valve and they all operate correctly with power on but with the boiler switched off. If I set programmer for hot water but not heating, when powered up the boiler will heat the water and shut down correctly. If I take power off and reset to come on in the morning the system will work but heating will continue despite the room stat call dropping off and the programmer ceasing to call. There are no error codes shown on the boiler display.
Could there be a software latch up in the boiler internal controls which is released by the reset control? Or does anyone have any other ideas or similar experience?
Thanks for any help or advice.