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Expansion Vessel

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  • 10-05-2021 7:52pm
    #1
    impr0v
    Registered Users Posts: 2,647 ✭✭✭


    Hi all.

    The expansion vessel on my domestic hot water system seems to have failed - water has come out through the inflation valve.

    This vessel has repeatedly given trouble since I bought the house three years ago. The pressure release value would periodically start venting water and, when I got the plumber out to explore why, the vessel would be full of water and need to be reinflated.

    My question I have is whether I should replace the vessel with a bigger one. The hot water tank is 400L. The vessel is not obviously marked, but it appears to be a standard 12L one.

    Looking online, there are a variety of inputs - system volume, max operating temp, etc., but as a rough rule of thumb, the suggestion seems to be that a 400L tank needs a larger vessel than this, and I wonder if that is contributing to the problems.

    Any views appreciated.


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    #2
    K.Flyer
    Registered Users Posts: 8,565 ✭✭✭K.Flyer


    Water coming out through the valve means it is goosed and needs to be replaced. Pumping it up was a waste of time.
    Off the top of my head the expansion vessel for that size cylinder is at least 25 litre, possibly 35 litre, with a pre-charge of 3 bar.
    If the safety valve (P&T valve) has been opening due to vessel failure, then should be replaced as well.


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