I have a Glow Worm 30Sxi condensing boiler which fails to respond (sometimes) to a demand for heat from either the central heating or hot water.

I works fine when it is cold (or has been off for about an hour) but when it is cycling, working normally to maintain the house temperature, it often takes 2 or 3 attempts to light (It is all automatic and will try only three times).

Unfortunately it does not always light by the third attempt so the systems fails and gives a ‘F4 Ignition fault (lockout) went out when lit’

When this is noticed and sufficient time has passed a simply off/on works fine and the boiler relights.

There is an expansion vessel fitted (since it is a large house) which maintains the system pressure (cold 1.6 bar, hot, 81 deg C, 2.2 bar) and the flue is the simple horizontal through the wall type (at a slight angle).

I’ve had my plumber and electrician round who cannot find any problems with the boiler, but are willing to carry on looking, providing I carry on paying them.

I therefore need any good practical advice please.

The manual states possible causes as:

No gas. Possibly not:-).

Insufficient gas. Again no, it heats up over 15 radiators.

Incorrect gas valve adjustment. I do not know?

Electronic ignition lead defective. It works fine when the system is not hot?

Check air inlet duct. The flue is only a meter and on a slight slope.

Check connections to igniter unit. I was told this was fine, but?

Thanks

Martin

In message , martinw
writes

I have a Glow Worm 30Sxi condensing boiler which fails to respond
(sometimes) to a demand for heat from either the central heating or hot
water.


Electronic ignition lead defective. It works fine when the system is
not hot?

Things expand when they get hotter

--
geoff

On Fri, 23 Dec 2005 23:51:42 +0000, martinw wrote:


I have a Glow Worm 30Sxi condensing boiler which fails to respond
(sometimes) to a demand for heat from either the central heating or hot
water.

I works fine when it is cold (or has been off for about an hour) but
when it is cycling, working normally to maintain the house temperature,
it often takes 2 or 3 attempts to light (It is all automatic and will
try only three times).

Unfortunately it does not always light by the third attempt so the
systems fails and gives a ‘F4 Ignition fault (lockout) went out when
litÂ’

When this is noticed and sufficient time has passed a simply off/on
works fine and the boiler relights.

There is an expansion vessel fitted (since it is a large house) which
maintains the system pressure (cold 1.6 bar, hot, 81 deg C, 2.2 bar)
and the flue is the simple horizontal through the wall type (at a
slight angle).

IÂ’ve had my plumber and electrician round who cannot find any problems
with the boiler, but are willing to carry on looking, providing I carry
on paying them.

I therefore need any good practical advice please.

The manual states possible causes as:

No gas. Possibly not:-).

Insufficient gas. Again no, it heats up over 15 radiators.

Incorrect gas valve adjustment. I do not know?

Electronic ignition lead defective. It works fine when the system is
not hot?

Check air inlet duct. The flue is only a meter and on a slight slope.

Check connections to igniter unit. I was told this was fine, but?

Thanks

The manual is listing out reasons for the boiler not igniting. Some of
these are more plausible (in your circumstances) than others.

Intermittent faults are really tricky to track down. It would greatly help
if you could make note of when the lockouts occur, which you have done.

The burner unit looks very very like the one used in the Vaillant Ecomax
boilers.

I would check of get checked the spark gap size.
I would check of get checked the flue gases, the manual has a lot of info
about this.
When the boiler lights does it rumble like thunder for a second or two
this might indicate a weak mixture?


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
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