My boiler will heat water, but if it has been running for a while (eg
deep hot bath) then a minute or so after turning of the water there is
a clicking noise from the boiler and the pilot light goes out. If you
turn on the tap just after running a lot of hot water the water is
very hot. Seems that something is overheating and causing a saftery
mechanism to trip. However, I have had 4 visits from British Gas (I've
paid for their insurance service!!) and each time they have failed to
fix the problem. Any ideas?