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Replace External expansion vessel on unvented system

Discussion in 'Plumbing and Central Heating' started by scotty221975, 9 Aug 2021.

  1. scotty221975

    scotty221975

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    Hi all,

    Have an unvented system with an external Aquasystem ARB18 vessel. The install is about 6 years old and in that time the vessel has been recharged once. However, once again it has filled up with water and is likely to break the bracket off the wall.
    I dont want it replaced with the same one, ideally an upgrade to a better manufacturer, so your recommendations for a reliable one would be great.
    This seems to be a simple job of emptying the cyclinder below the line in the picture and islolating the feeds. Then just unscrewing the flexihose from the cylinder and capturing all the water that comes out, then screwing on the new one once it has been compression tested.
    I would assume no longer than an hours work and the cost of the vessel so no more than £200 in the Hants/Dorset - but such a simple job Im tempted to do it as have done loads of "basic plumbing" (bathrooms, kitchens, rads), but preference would be to get a pro in as long as they dont quote anything above £200. Is that a realistic price these days? Cheers
     

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  3. oldbuffer

    oldbuffer

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    Unvented hot water cylinder therefore NOT DIY, must be a G3 registered plumber.
     
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  4. scotty221975

    scotty221975

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    Yep - standard reply for unvented - happy to pay a G3 plumber - want to be sure they don't fit the same kit and don't get overcharged. So the questions were what kit is reliable and what sort of price.
     
  5. Agile

    Agile

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    I am not sure that any particular make is much different from any other.

    But I am thinking that you are expecting too much from your EXV.

    I am sure that you check and top up your car tyres every few weeks so why do you not expect your EXV not to be checked for three years at a time.

    An unvented cylinder is expected to be checked/serviced every year and that would usually include checking the EXV. Not just the static pressure but probably letting all the air out ( which can also contain water on the air side! ) and repressurising.
     
  6. scotty221975

    scotty221975

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    Hi I have the boiler serviced every year by Valliant (although they use subs) as a condition of the ten year warranty so would expect them to keep an eye on the system ., however I cant recall him ever going upstairs to the tank or cylinder. Its due for its next service next month so will keep an eye out if he goes upstairs! The installer of the system was in last year to pump up the vessel and said it was unlikely to last much longer, however looking at Gas Safe the installers of that firm now have no unvented certs so hesitant to get them back in.
    If six years is the lifespan then thats fine. If they are all on a par with each other then dont understand the massive range in price from £40 to well over £150, with some providing warranties of five years. Surely some have better membranes than others and installers prefer certain makes to others for reliability. The bracket setup for this one is well dodgy as if it breaks off the wall it will fall on the other pipes and I'll be in a whole lot of trouble!!
     
  7. ianmcd

    ianmcd

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    There is no requirement to register unvented qualifications with Gas safe, some do some dont, the engineer shoud be carrying an ID card showing his qualification though, as it requires a G3 qualified engineer , it is against site rules to advise you how to replace it, all i can say is the method you suggest is wrong
     
  8. scotty221975

    scotty221975

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    Cheers - that makes sense - yeah the temptation to change it myself is gone! Happy to get it done by G3 engineer but an idea of how long it will take so I can gauge cost would be a great help, as if I point it out to Valliant service guy Im sure the cost will be astronomical and they'd yellow tape the system and switch it off if I didnt proceed.
     
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