On Wed, 11 Jan 2006 14:32:54 +0000, Andy Hall wrote:

On 11 Jan 2006 02:04:09 -0800, "Bal" wrote:

I have checked the flue, all is clean, clear and the fumes are coming
out as normal.


OK.

If you are still getting the main burner and pilot cutting out after
having replaced the thermocouple (but it has improved), then the only
things left are the overheat thermostat (I think you had a suggestion
on how to test that) or the gas valve.

The thermostat would be pretty cheap I would have thought. By the
time you get to a new gas valve I'd start to wonder if it's worth it
in a boiler of this age and whether replacement would make more
economic sense.

I'm still concerned by the flame colour though. It would be a very
good idea to get the flue gas composition checked for carbon monoxide.
Realistically, that is a professional job since flue gas analysers
cost around £200+

The main causes for the OPs problems would be.
1) Lack of primary flow leading to over heating and shutdown.
2) A poor connection on the overheat stat that is set off by a slight rise
in temp.
3) A duff overheat stat.

N.B.
If the flames are yellow like a candle stop using this appliance, even
though it is a room sealed appliance.


--
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