Central Heating Problems ,, Burners not igniting

[runner20k]

Hi can any one help ,, i have a Chaffoteaux et maury, Corcev 28BF central heating boiler. The pilot light , lights up ok with no problems apart from the fact that if fluctuates from a big flame down to nothing and then back up again but does not go out. If i turn the thermostat up i can hear the pump kick in and start to work but the burners in the boiler window do not ignite like they used to,, hence no heating ,, anyone got any ideas as to what could be wrong. Which part of the boiler controls the signal from the thermostat to turn on the gas to the burners ???????

any help much apreciated as its cold in this house.
and to close after chrimbo to afford an experts visit.

 

[Agile]

This is really an instant water heater which has been modified to kind of work as a heating boiler.

It works totally without using electricity and the boiler is turned on by the water flow generated by the pump.

Because of the way it works I would not recommend that anyone other than a CORGi engineer who understands it should work on it.

Apart from anything else the case seals are not very clever either.

Tony