Hi everyone i realise this is an old thread but I have a similar issue....my combo goes on and off every few seconds....i have got 1.5 water pressure and I have already taken off the heat exchanger and cleaned it...when I set the boiler to just DHW nothing at all happens....when i set it combined CH it does what you will see in the video link below.....
I have tested the NCT and it is functioning well at 11500 ohms of resistance so its not that
I have also opened the control box and pressed down the diagnostic switches which you will see in the video
I am an electrician (formerly) now school teacher therefore handy enough on things..was able to fault find the nct from the board rather than disconnect it etc..so I am hoping that someone could help me find a way to fix this without having to call someone in...video link below ...thanks all..
I have tested the NCT and it is functioning well at 11500 ohms of resistance so its not that
I have also opened the control box and pressed down the diagnostic switches which you will see in the video
I am an electrician (formerly) now school teacher therefore handy enough on things..was able to fault find the nct from the board rather than disconnect it etc..so I am hoping that someone could help me find a way to fix this without having to call someone in...video link below ...thanks all..