Cheers scatmanjohn.
I'm still puzzled as to where in the boiler the pcb is located, is it behind the control panel somewhere - I'll admit I've not taken the boiler cover off yet, it might be obvious!
Also, am I right in saying that the preheat is done by an electric coil or something then...
I moved into a new house at the end of last year which is 5 years old & has a linea 726 boiler installed.
Recently I've noticed that it is making a noise overnight, which is waking me up, but when I've looked at the boiler it doesn't seem to actually have fired up - the noise lasts about a...