please help!

[nabby68]

have just moved into my new house, so not really sure how old the boiler is but the house is about 10 years old and i think the boiler is probably the same, it is a Gloworm Ultimate. The problem i am having is that after swiching it on, after about 10 - 20 mins the burners shut off and also the pilot light goes out and as it shuts off i hear a bit of a clunk sound.
could this be the gas valve shutting off or could it be my thermocouple thats the problem? any ideas?
p.s i have checked my pump and that is working ok, so could it be a build up of sludge int he system causing a blockage and therefore overheating the boile.
i have posted this previously, but didnt get much response, heres hoping someone can help

 

[tomy]

Sounds like it is overhating and cutting out the thermocouple as a safety measure, check your pump and that there is no air in the system

 

[nabby68]

hi tomy. have checked pump and that is running fine and i have bled all the radiators. could it be a sludge problem?