T i m wrote:
Hi All,

Some good friends asked me if I knew any good heating engineers and
pre passing any names on thought I'd have a quick look at it myself (I
had helped them change the blower in it a few months ago).

It goes like this ..

Power on, fan spins (good blast of air outside) .. 30 sec later gas
control solenoid pulls in (presumably 'pilot stage?) and electronic
igniter tries to fire up the pilot. After a few tries (it's always
been like that apparently) the pilot lights but immediately (.75 sec)
goes out with a loud sort double clunk from the main gas valve and the
cycle repeats.

I've checked all the obvious (air pressure / flow? valve switching
over, wire all intact, pipe all in place etc) and am about to get /
fit a new HT lead as I thought I heard it arching out somewhere and
also though it was part of the flame failure detection cct (and
hopefully it's cheap) but I don't feel confident it is that?

Failing that (ouch) then could it be the electronic igniter / pilot
control box doodad (407676 / £100, I've checked the back of that for
dry joints and it looks ok) or what else please?


Check the ignition lead forms a low resistance dc path from electrode
to control box. A break will jump the spark but not register the flame
presence