On Sun, 15 Jan 2006 15:50:44 +0000, Bob Smith wrote:


"Belly" wrote in message
oups.com...
I would check by replacement the electrode cable, also does the pilot
establish at all? If the boiler is failiing during the igntion sequence
then it is unlikely to be the control board. It would also be worth
will inspecting the pilot injector to ensure it is clear of any debris.
Failing that then replacement of the Ignition board would be the only
logical course of action. By what you have described above the gas
valve is operating OK. It is not likely to be a sensing problem or an
air pressure switch problem, if the APS was faulty then the boiler
would not get as far as ignition in the first place.

Belly


I don't think it is the electrode - the normal order of events is: fan on,
small click (APS), clunk (gas valve), tik tik tik (spark) whumph (loads of
flames). When the boiler is not lighting, it does not open the gas valve,
so does not get as far as sparking up.

I fixed the multiple clunking - wobbling the thermistor connector made it
happen. It seems to be off for so short a time, the ignition sequence is
not stopped, and the gas valve is opened again. When I recreated the
multiple clunk thing, it also made it go into silly mode (ignoring
temperature dial of thermistor, lighting up in pump run on time etc). The
loose connection was not in the wire, but between the plig and socket, so I
bent the pins slightly to make a more permanent connection.

Which bit makes you think the gas valve is OK? Is it the solid CLUNK, with
no weak ones ever, or the fact that it lights at all (ie is the solenoid
likely to cause an intermittent fault like the one I have?)

I see from the previous posts that you replaced the APS. Does this give
the correct readings each and every time?
Have a look at the inlet tubes to the APS they can attract debris which
totally screws them up.

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