My boiler is 28 year old, still going well and serviced with BG contract. However lately it has been slow to ignite, fan running but no ignition for about ten minutes on occasions. Called BG and immediately diagnosed(guessed) without physically checking that a new mercury vapour valve p/n 41-601-35 was needed. These are no longer available and recommende a new boiler. How can I be sure that this part is faulty, or could it be perhaps a blockage in the pressure valve as I am informed the symptoms are similar.

Dave, September 2008

Does anybody know where I can get hold of a gas valve for this boiler

Lisa, November 2009

I have a problem (via my plumber friend) with the vapour valve switch on my very old potterton netaheat 10-16 boiler. Although still working at a very low gas pressure giving very lukewarm temperatures to the radiators, the plumber has isolated the problem (by a process of elimination) to be the vapour valve switch not working properly! We can't find a replacement in this area due to the age of the boiler and even if we could, a price of £200ish for a new part is not worth paying on a boiler on its last legs! I will be gutting my kitchen in a couple of years (cant afford it now) so I would prefer to keep it going a bit longer. Does anyone know where I can get a cheap or secondhand replacement valve to keep it going, or even have an old one lying around we could work a price out for?
Also how can you tell if the boiler is a Mk1 or a Mk 2 model?
Cheers
Graham

Graham, February 2009

We have a parts counter and have in stock a mercury valve for your model of boiler. If you still require it our no is 01782 279504

GT Thermal Ltd, October 2008

sorry just had a thought. did you say mk1 as that one does not have a mercury control these were only fitted to mk11 models - sorry

Paul the gasman, October 2008

yes i would agree it is the mercury switch which is operated by the pilot to operate the gas valve. - it always is no need to check. original interpart number 402801 or new number 402836 SWITCH, M/VAPOUR. or if you get the whole gas valve assembly the interpart number is 402499 Gas control valve, White Rodgers K25 1 g.c number 392745. but it must be fitted by a corgi engineer

Paul the gasman, October 2008

I am an engineer in the gas industry and would agree and also mention that their is a problem with your boiler that can couse productus of combustion to enter the room so would strongley recomend a new boiler.

Adam martin, September 2008