I have a Potterton Profile 100e fanned balanced flue gas fired boiler installed in 1996. It is regularly serviced. In the last couple of years it has tripped out usually at night for no apparent reason on a number of occasions. A press of the reset button on the bottom sets it going again. The handbook says this can arise from an "overheat condition" or because of an interruption to the electricity supply.
It is not the latter since the very sensitive electricity supply trips we have in the house [after a fire] are not triggered.
The service company says it can find no reason for any overheating.
If it were overheating, what exactly would be overheating and what would be the remedy?
What other cause might there be and what remedy?