Got exactly the same problem as seen below;
'Fault condition - boiler dead to all intents and purposes - all neons out except 'fan on', which goes on and off accompanied by a relay like clicking sound.
If pot is turned down fan light stays off and clicking stops.
Occasionally if left in this condition, after a few hours the 'boiler on' light springs on, the pot can be turned up and the boiler works ok for the next 12 hours or so, before returning to the above fault condition.'
I am hoping it's not going to be too expensive, but looking at the possible faults I think it might be.... Will keep you posted on what the engineer finds [unless he tries to rip me off] ..
Chris, February 2010