"geoff" wrote in message
...
In message , Colin Swan
writes

SNIP

I hope it's not the pcb ...

Can you see it sparking in the combustion chamber?
It might be sparking somewhere else

Is the pilot igniting?
If so, there's a high value resistor which, if gone wouldn't allow the
pcb to sense the flame


I've just had two intermittent failure to sense flame problems on different
boilers:
One was simply a loose auxiliary earth wire on the burner which then
sometimes completed the circuit via the boiler metalwork and occasionally
didn't.
The other was on a housewarmer back boiler and the end of the
ignition/sense electrode lead had corroded off within the porcelain mount.
The spark could jump the gap but the sense current couldn't
In both cases of curse the pilot did light but the boiler didn't think it
had and so went into shutdown.

If not, it sounds like the valve isn't working. Check that there are
(about 110V DC (can't remember offhand)) volts on the pilot valve
contacts. If there are and the valve's not opening, you have a faulty
valve, otherwise, I'll be expecting a phone call from you. If the pcb
does not sense the flame within a certain time (13-15 sparks) the boiler
goes into lockout.

If you still have problems, give me a ring (01923 229224)


So, any ideas on what the problem could be? Even if I have to end up
calling in an engineer, I'd like to be pre-armed with some info.

On a related subject, the boiler is in my new downstairs cloakroom on
the wall above the short soil stack. The stack has been boxed in, with
the boxing continued up to the ceiling, so that it also covers the
side of the boiler. As this interferes with the boiler cover and will
need to be cut away to allow service access, I am thinking of building
a cupboard around the boiler. Are there any regs to do with this? Any
advice on how much space to leave around, ventilation, etc?

Check your installation and service instructions which "might" say you
don't need purpose designed ventilation but if they dont then yes you most
definitely do and the sizing is remarkably large when you look into it for
older boilers (based on the boiler input rating)