Hi I'm new to the forum and looking for help with a Potterton Suprima 50L

The problem is elelctrical, the boiler trips my rcd over night and will not let me reset it. I traced the fault to the boiler itself which had a dead short between neutral and earth.

I took the whole lot apart and found nothing obvious so I wired it all back up and it ran fine with no sign of a short or any other problems until this mornining when I woke up it had tripped the rcd again.
The boiler is only about three or four years old so not exactly worn out.

It has been suggetsed that I need a different rcd and this problem is also common with fridges? (Now More puzzled)

I'm stumped so any help would be hugely appreciated especially if it avoids a £240 bill for a new pcb.
Thanks Brian.