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Very slow leak in gas heating system - looking for seal recommendations / advice

Discussion in 'Plumbing and Central Heating' started by stephenco, 5 Mar 2018.

  1. stephenco

    stephenco

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    I've a 5 year old gas heating system which I have to pressurise every few months and which I'm assuming has a very small leak somewhere.

    I've searched but can't find it. Someone told me I could add some sort of sealant which may cure it. Can I ask for advice please.
     
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  3. terryplumb

    terryplumb

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    Don't put leak sealer in the system. It can cause more grief. If you only top up a few times a year ,don't worry about it.
     
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  4. CWHEATING

    CWHEATING

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    LOL micro leaks. Bane of my existence. I’ve found most the time pressure is being lost from small leaks in boiler. Get qualified engineer to remove casing and look for any small signs of water damage/leaks. Usually it’s to do with auto air vents leaking slightly then drying up due to heat produced by boiler, it usually leaves a water residue that looks like a crust. Or it could be to do with various boiler seals. Another thing check radiator valves or radiator bleeds. Slow leaks usually dry up before showing any signs of actual leakage. Also another reason for lost pressure is air in the heating system working it’s way round then to your boiler and released out of the auto air vent on boiler. How old is your boiler and how old is your heating system?
     
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  5. stephenco

    stephenco

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    All good advice Cwheating, thanks for this. The gas boiler was installed around 5-6 years ago but the pipework and rads are around 30 years old.
     
  6. ianmcd

    ianmcd

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    I wouldnt worry too much about having to top the pressure up every few months and as correctly advised dont put leak sealer in , it cases more harm than good
     
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  7. m0t

    m0t

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    I just added some leak sealer to my system, what sort of issues does it cause?
     
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  9. ianmcd

    ianmcd

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    If you have a modern boiler some of the waterways are very small and leak sealer can block these, it also jams some small moving parts within waterways, if you have a leak fix the leak, dont turn your system water into mud.
     
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  10. CWHEATING

    CWHEATING

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    Because your system is so old then pressure loss is to be expected. Until you see a dramatic loss in pressure then everything should be ok just topping up the pressure when needed. It’s always a risk when replacing old boilers on old heating systems to go for pressurised boilers.
    Like the other guy said sometimes these leak sealers can do more harm than good. Probably best to drain your system and add some inhibitor.
     
  11. TicTac

    TicTac

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    Have a look at the overflow pipe from the PRV, and see if there's any signs of a leak; fit a clear plastic bag over it if in doubt, and see if any water comes out.
     
  12. chrisw99

    chrisw99

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    I recently had a new boiler fitted and it says in the manual it is normal to top up the pressure every few months because the pump in the boiler expels air present in the system over time.
     
  13. CWHEATING

    CWHEATING

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    I haven’t topped up my boiler for 8 months now and the pressure gauge still sits a 1 bar when cold. Perfect.
     
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