Vaillant combi boiler - pilot light keeps going out

Hi,
I've got a Vaillant VCW combi boiler. The pilot light on this ha started to put itself out several times a day - what seems to happen i the gas coming on when the boiler fires up (e.g. when you turn on a ho tap or the heating) occasionally puts out the pilot. I have insuranc cover whereby if the heating/hot water breaks my insurance company wil send someone to repair it; however, when I spoke to them on the phon they said they'd only do this if I first wait until the pilot ligh *always* goes out when the boiler fires up. I therefore thought I' check if it's likely to be anything obvious/easily sorted.
Have checked that the temperature the boiler's set to is appropriat for the (lousy) weather, and the only thing that looks slightly amis is that the pressure is down to just over 0.5 bar - this is above th 0.5 bar recommended minimum, but only *just*...is it worth trying t raise the pressure and seeing if this helps matters? And can this b done by just turning a valve marked 'filling valve' to 'open', or is i more complicated than that?
Cheers,
Jo
-- diaj
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On Thu, 24 Feb 2005 15:04:39 +0000, diaj wrote:

As for filling the boiler see the FAQ below.
The three most likely reasons for the pilot going out are: 1) The boiler's over heating (or it's sensor thinks it is). 2) There is a poor flame on the thermocouple and a bit of draught causes it to cool down a little too much. 3) The thermocouple is dying.
If you find that you can release the 'start' button within a few seconds after lighting the pilot - i.e. you don't need to hold it in for the full 20s or so to light it ... then I think 2 or 3 are less likely.
The t/couple is a custom unit on these boilers around 10 instead of 4, because they incorporate the connections to the Over-heat cut out.
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Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
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