Help, boiler not working

[kitkat]

ihave a ravenheat csi 85 condensing boiler when i run the hot water the boiler fires up for a minute then cuts out, it will do this a few times and then stop altogether until i leave it for a while. have had an engineer out to look at it and he said it was the pcb which is 180 pounds. but a friend thinks it could be the overheat thermostat, because the boiler will sometimes stay on for a bit longer if i havnt switched it on for a while.
does anyone have any ideas.

 

[Agile]

Its very difficult to guess without doing any tests some of which needs a CORGI.

Before condemning the PCB, I would have exhaustively checked everything else.

Its usless having an engineer who "thinks" its the PCB. If he "thinks wrongly" then he may expect that you should pay for a new pcb and his wrong fault.

Better to make sure you get someone who will do a no-fix no-fee.

Tony

 

[timmy74]

if only doing it on hot water could be problem with secondary heat exchanger blocked up, cutting out on overheat?

 

[kitkat]

thanks for the advice, at the moment the boiler is working fine, but it has done this before then stopped working again after a few days, seemed to baffle the engineer i had out, and he was corgi registered.

 

[ChrisR]

1) intermittent faults can be baffling, and not mendable unless they show reliably.
2) Corgi Registration means only that someone's safe to work on gas, nothing much about knowledge on how combis work.