On Mon, 22 Jan 2007 22:19:56 +0000, raden wrote:

In message , T i m
writes
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?

Flame detection is in the 407676 (assuming that that is the version you
have, i.e. a netaheat electronic)


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?

It sounds like the GV relay on the pcb is not operating correctly for
whatever reason.

... unless someone like Ed has any other ideas

As someone else said, my website

www.cetltd.com is your best bet

Do all the low tech stuff first.

clean the burner, check the electrode, lead and gas supply pressures.

Then get a module.

If that does not fix it you'd have to say it was some weird GV problem
which might put the boiler beyond economic repair. The boiler around 20
years old.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards