"P Lavers" wrote in message
m...
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?

If I understand this correctly, it is after the boiler does a burn, that the
system clicks and the pilot flame goes out ? Or does the pilot flame go out
and then the clicking noise is heard.

I think the clicking sound is the gas safety valve closing off to stop the
pilot flame injector from leaking gas into the body of the boiler. And this
fault, if it is happening after the boiler does its burn, is more than
likely to be the hot flue drawing air in and around the pilot flame and
blowing it out.

To test this, get a piece of wooden board (plywood or hardboard is OK) and
block off only the bottom half of the flue. Now if the flue is a balanced
or not, it doesn't matter, and all you need is the bottom section of flue
pipe to be slightly blocked. It also doesnt matter if the flue is of the
type with pipe in front of the other, as slightly blocking either the intake
or the outflow will tell you if the pilot flame is being drawn out by flue
gasses after the boiler has heated.

If it shows that the pilot flame remains lit after doing a few burns and
cools with the flue partly blocked, then call the gas company back and ask
them to slightly increase the pressure of the gas supply to the pilot.

If it doesn't show any improvement with doing this test, then you'll need to
have the engineer back to carry out other tests to find the real reason.

Remember not to block the whole flue, ONLY THE BOTTOM HALF OF IT. And keep
the barrier there for any more than the length of this test. The test
should only last for the time it take the boiler to cycle through two or
three burn patterns and not to extinguish the pilot flame.

This is not a cure for the fault.


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