Just had a heating guy round, he tested fuck all claimed it was a blocked heat exchanger causing it to overheat and wanted me to buy a new boiler. Going from a conventional to a combo. £1400-£2000 So once he had gone I fired it up and waited the few minutes till it tripped out, I then removed the over heat probe (Still wired to the PCB though) And tried to fire it up again which it would not do, which leaves me to believe its not an overheat issue.
On my ideal the thermistor went 5 times which caused the heat exchanger to warp. On the 5th time they replaced both items and I got British Gas to take over servicing from Ega Heating as the last boiler failure I went 7 days through the hard winter we had 2 years ago freezing!!!!
The pcb might need to see an input, from the sensor, to work. As said above, is there water in there? Can you not stick some system flushing fluid in?
is the over heat probe a stat (a limit stat ) that cuts the burner if the standard stat fails. if the hot water isn't getting away then the standard stat operates ie its not an over heating issue. im not a gas safe plumber/heating engineer ( im oftec mostly oil over here ) so cant really advise except use someone qualified ask for the gas safe ID, get them to repair and service it. if anyone tries to sell you a new boiler seek second opinion. if possible only use a plumber/heating engineer who is recommended by a friend. and have a co detector near the appliance.
