My lovely (very cheap 15 years ago) boiler has started to cut out for no reason. I can light the pilot light and it works fine for say 15 mins, then ... gone... i go up light it again.... another 30 mins... gone...... i then do this again and sometimes it can stay on all day and even to then next morning when it switches on.... but that evening... nothing !! I thought it could be the thermocouple but the pilot will light (if a little bit slow) but it will just not seem to hold the pilot for a great period of time. When it last went out i was in the loft and heard a click sound when it went out, as if i had switched the controler to the off position (which i had not). Any ideas on the cause of this... i don't want to get another boiler as my ''old faithful' is now part of the family.....