Boiler tripping out

[sleeper]

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?

[Eragon]

I have a Potterton too which has tripped out since new (6 years). The engineers don't have a clue but they insisted it was overheating. In fact there is a separate over heat switch which has never tripped out. My problem is in fact 'flame failure'. Worth checking.

[htg engineer]

Does it go off more if the heating is used through the night ?
or if the hot water is used ?

It could be a faulty overheat stat.
Or possibly even a fault on the PCB - which can occur with age.

htg

[sleeper]

Eragon - how was your 'flame failure' fixed?

Htg engineer - the water stays on all night but the heating never. How would I locate a possibly faulty overheat stat and check it? Likewise check the PCB?

Thanks both of you for coming up with some possibilities

[htg engineer]

You should be abvle to get the overheat stat from any heating spares store for under £10, this is the cheapest part to replace (PCB £130) rather than spending time trying to determine if this is the fault - I would replace the overheat stat and see how it goes.

I can't imagaine £10 breaking the bank, and may solve the problem.

http://www.onlineboilerspares.com/product1812.html


htg

[sleeper]

Thanks Heating engineer. I'll try that.
Regards :)