Potterton Problem

Hi I'm new to the forum and looking for help with a Potterton Suprim

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

I took the whole lot apart and found nothing obvious so I wired it al back up and it ran fine with no sign of a short or any other problem 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 wor out.

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

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

-- bfinl