Postby mickey1 » Sun Aug 30, 2009 2:52 pm

The problem is. my central heating system(combi boiler) loses pressure, albeit slowly over a few months . at first i thought it just some air in the system taking a long time to escape, but i've noticed there is a lot of vapour coming out of the outside outlet pipe when the boiler is in operation. is this right?, the system is supposed to be a closed off pressurised sytem, so i guess it must lose water in the form of vapour . am i supposed to be repressurising it so often?
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Postby htg engineer » Mon Aug 31, 2009 9:16 am

It's more likely to be a small leak somewhere in the house, under floor etc etc, Water vapour is a waste product through combustion so there will be vapour from the flue.

htg engineer
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Postby mickey1 » Mon Aug 31, 2009 4:26 pm

Thanks for the reply. a lot of water vapour does come out though. the leak must be really small, i will never find it without taking up carpet ,flooring, etc!!!! do the sealing products work??
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Postby Carl83 » Tue Sep 01, 2009 8:57 pm


I agree that you must have a small leak.

Sometimes well hidden under floors.

You can always try a leak sealer and yes they do work. I often give customers the option to use them as it saves a lot of money.

Try fernox or Kamcos brand

Buy the concentrated form that comes in a tube. This is injected via an air cock

It will work as long as the leak is not a big one but you would know if it was

Good luck and ask if you need more help
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