Ideal classic thermal cutout issue

Hi everyone,

Two questions at bottom of post. A little introduction to the issue:

I have an Ideal Classic boiler that unpredictably cuts out (red cut out button pops out on the side) and has to be reset. After paying a heating engineer £200 to service, replace autovalve on hot water system and install a new air release valve (all his suggestions) the problem still persists.

Fed up, I spent some time trying to diagnose and believe the problem is that the thermostat on the front of the boiler doesn't work. Ie, when the boiler is up to temperature turning the thermostat knob from 6 down to 1 does not stop the boiler burners.

I assume that either the thermistor and/or the pcb that controls the thermostat is / are broken. This means that the boiler will continue to heat until the hot water is up to temperature or the house is up to temperature (central heating) or the thermal cutout temperature is reached.

Question 1) How much is a new thermistor and / or a new pcb and where can I order these from?

Question 2) Can I replace either of these myself (not a plumber or heating engineer, but competent with fettling).

Many thanks for any help you can give!
Tom

ive had the same prob on a job and it turned out to be the thermister, but i didnt end up changin it as i couldn't get the bl00dy thing out the pocket!but it worked ok after id played about with it??? id get sum1 in to change it as ya have to remove the case (which seals the fumes inside).. as for cost iam not sure but i could find out if ya give me the gc of the boiler

Thanks gas_man_gaz for that. Definately the kind of information that makes these forums worhwhile!!

I was about to delve into the inner casing to retrieve the thermostat sensor but checked the control board first. Turns out that the 3 wire connector from the thrmostat knob on the front of the boiler was completely diconnected!!!

I reconnected the plug and the thermostat control started working perfectly. Obviousdly I was happy, but even more disapointed that my plumbers didn't notice the problem. Should I name and shame them??

Many thanks again for your input,
Tom