Removal of sludge from boiler without full system flush

Discussion in 'Plumbing and Central Heating' started by wizardsaleem, 8 Aug 2009.

  1. wizardsaleem

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    Hi all,
    There appears to be a resident sludge in the pipework of my vaillant boiler 828, possibly causing erratic movements of the needle on the pressure gauge. I wondered if I could clear the boiler without having to do the full system flush. Also, I suspect that even if I did the full flush there would still remain some contentious amount of sludge in the boiler perpetuating the problem.I understand there could be loads of other reasons for the pressure gauge wayward behaviour but I would like to eliminate the sludge possibility.So. please advise how the boiler pipe network can be cleaned up.

    Many thanks.
     
  2. knuckles

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    Fit an Adey Magnaclean filter on the return pipe of the boiler and dose the system with two cartidges of Sentinel X400. You'll have to run the central heating to circulate the chemical. Probably £120 +VAT.
     
  3. wizardsaleem

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    Thanks for your reply. But I was kind of hoping that I might be able to discnnect some pipe inside the boiler at some strategic point to drain out the muck. Perhaps on or near the pipe where capillary connects.
    Regards.
     
  4. mickyg

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    even if you could and did do that, you haven't cured the problem just made a temporary fix, there's obviously dirt in the radiators contaminating the boiler, this needs a remedy. Otherwise it will soon come back. If the pressure guage is flicking then more likely a partially blocked main heat exchanger.
     
  5. gas4you

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    It is a very common problem for Vaillants to collect 'sludge' in the HE coils at the bottom.

    Usually this shows itself in a horrible droning noise when the boiler is run on full power.

    You can isloate the boiler from the heating system via the valves under it, then attach a 6mm rubber pipe as a drain on one of the drain offs, pressurise the boiler and back flush just the HE, into a bowl.

    It will be best to run the boiler whilst doing this and to also run a hot tap, so the plate HE gets flushed as well,

    The plate HE, otherwise, will just act as a store for more sludge to return later.

    I agree that fitting a magnaclean is a very good idea, as is Mickyg's statement about a proper flush of the system.

    The above, however is a way to acheive the limited cleaning you asked about.

    I have carried this out several times now, sometimes adding X200 after the HE has been cleaned.
     
  6. bengasman

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    Very rarely is the gunk just located in one or two places, only cleaning the hex is most likely a futile exercise.
     
  7. Paul Barker

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    My lodger got full hot water performance back a few months ago puting two bottles of x800 in which I supplied him and running the heating and a couple of baths. Different boiler to yours.

    This method treats the whole system by running rads, and the plate heat exchanger by running baths.

    His hot water performance has remained perfect.

    I could have powerf;ushed but I am a very busy person, and it takes a cart horse to drag me to do heating work on my day off, so I let him try this method. Yipee it worked.

    My boiler in his flat is just a Baxi 80e though which wouldn't suffer from dirty system water in the main heat exchanger in the way a stainless steal one does..
     
  8. David937

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    That sounds good, was it a large system; two bottles of X800?
     
  9. Paul Barker

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    No it's a small flat, but I wanted to zap it good and it worked a treat..
     
  10. David937

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    Do you think one bottle of X800 left in for a week or so will give similar results?
     
  11. Paul Barker

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    I think it says 4 hr max on bottle.
    A rep told me these days it deactivates
    over next day once opened.
     
  12. David937

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    Thanks :D
     
  13. gas4you

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    Don't forget, X800 in an aluminimum HE is a maximum of 3 hours.
     
  14. mehran

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    hope they flushed out the two bottles of x800 well :eek:
     
  15. wizardsaleem

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    Suppose it was a partially blocked main heat exchanger, what is the way to unblock it,please? The pressure gauge appears to have lost much of its sensitivity.

    Thanks.
     

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