Hi
The problem is when I put the CH on full the boiler fires up the temp on dispay goes to about 60 then the flame cuts out whilst on full. It then cycles on and off every 30 Seconds

Pedro, October 2008

try flushing out the heat exchanger with a good descaler.

pat, October 2008

Check if the differential air pressure switch is cutting out (careful, mains voltage), if so suspect flue venturi needs cleaning. Even a small deposit build up can stop it working reliably and give that specific symptom. Google 'venturi temperature cycling flue venturi'. To clean the venturi you must remove it from the boiler, not difficult but a job for a corgi man. It can not be cleaned by pushing things down the spigots that the silicone tubes push on to.

c, October 2008