Quicky on changing expansion tank

Discussion in 'Plumbing and Central Heating' started by vice, 29 Mar 2020.

  1. vice

    vice

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    Hi. Quick question on changing an expansion tank. First one I've done but 17 rads on an 18 litre. Pretty sure the bags failed. Going to put a 25 litre on but can I close off with the valve underneath the tank connection? Or easier done with a quick drain and under vacuum please.
     
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  3. ReJect

    ReJect

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    You are not supposed to have any valves between expansion vessel and system.
    Can you not freeze the pipe?
    Or if you can close off any auto vents and drop the pressure fully it might be possible to swap, perhaps by still plugging pipe temporary while you struggle to fit new vessel.
     
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  4. vice

    vice

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    Thanks.
    To be honest I'm still scared to freeze pipes. Seen it push compression fittings right off in the winter!
    Will do the vacuum thing I think.
     
  5. ReJect

    ReJect

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    If you have the basic freeze kit of a jacket and can of freeze spray it would be easy.
    Freeze spray won’t burst the pipe.
    It just forms an ice plug.

    As to pipes freezing and compression fittings pulling off in severe winter - the 2010 winter was so bad could burst anything including soldered fittings.
     
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  6. vice

    vice

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    Cheers.
    Wonder if I can just turn a £1 air duster can from poundland upside down to freeze! :D
    (do not do. Not advice. Just noticed...)
     
  7. picasso

    picasso

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    Personally I always fit an isolation valve and a drain point on an expansion vessel, makes life so much easier to service them.
     
  8. ReJect

    ReJect

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    If water pressure is fully dropped off a sealed system you might find no bother from water coming from the open pipe (if auto vents are all manually closed using their wee plug cap).
    But the old faulty vessel will be full of water and very heavy. Can be difficult to hold while disconnecting
     
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