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Cold water tank overflow since drain down

Discussion in 'Plumbing and Central Heating' started by tommy8884, 24 Jun 2021.

  1. tommy8884

    tommy8884

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    Hello,

    We had a new rad fitted by a plumber last Friday. The system was drained down to facilitate this (tails needed moving).

    Anyway after the job my hot water didn't work, i bled the coil which fixed that. Now i have noticed that the overflow (which is snapped off at the wall) is dribbling down the side of the house from the loft. This is to the point that, its gone through the brick into the plaster on the inside of the house and also making the oak frame window expand.

    Ive been up here and i can hear the bigger of the two tanks (the cold water for the cylinder i think), does continue to run a fair while, so i think its that. Now problem is there is no access to adjust it, the roof is far too low. I can just get my phone in to take a pic. Strange thing, there is no lid, but there is an insulation jacked floating inside, under that ball cock. Is that normal?

    I cant reach the ball cock to make any adjustments unfortunately.
     
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  3. fixitflav

    fixitflav

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    No pics attached. Did the plumber go up the loft, and do you think it's anything to do with his work?
    If it's overflowing it sounds like the ballcock is not closing properly, but even so the water should be directed away from where it can cause damage. It needs sorting quick! As a stopgap, I would isolate the feed to the tank and open the valve again every now and then to top it up.
    The insulation jacket shouldn't be floating on the water! Is it by any chance tangled round the ballcock and jamming it part open?
    Presumably somebody got enough access to it for installation.
     
  4. tommy8884

    tommy8884

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    Hi, I cant attach any pic as there is only just enough room to get my hand in. I cant see in there, no way, i had to take a video on my phone to see what was going on (cant see how to post that). It may have been installed when the house was constructed in 1967, its an old system.

    The black insulation jacket is in the water, under the ball cock! Doesn't look tangled and it is currently stopped by the sounds of it. Its a very slow drip though.

    The plumber did go in the loft (dont know why), maybe just to have a nosey as he is also angling to replace the lot (being a 25 year old boiler and a one pipe system). There was no problem prior to this work. My guess is the heating was drained down, thats upset the ball cock (or maybe h tied it up to stop the tank filling and that's upset it). Ill try to get hold of him, but will shut off the supply now.

    When i did initially get a response from him, he stated it would have been the expansion tank from trapped air, i am not so sure now as its 1 week on and the hot water has been on daily no issues.
     
  5. polesapart

    polesapart

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    Your plumber (probably) went into your loft to check the alignment of the pipework and if there were any any vent points to release trapped air.

    If the ballcock is letting by he can fix/replace it: this would be reasonably viewed as an unforeseen extra and chargeable as such.
     
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  6. fixitflav

    fixitflav

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    I once tried to post a video and it didn't work. You can post still pics OK.
    Do you mean you can see the jacket is under the water but can't get at it to remove it? It wants taking out, if it's under the ballcock that could be the problem. You might be able to refit the jacket after it's dried out, if not a rigid polystyrene foam board could be the answer.
     
  7. tommy8884

    tommy8884

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    Ok do removing the jacket from the water made it worse. I suspect its been under there a good while and has caused the valve to be pushed up. Draining down has moved things and upset it. It's back in under the cock and it's stopped for now. I've also pushed the overflow pipe out as far as I can away from the house which is only an inch. I will get a new pipe in tomorrow as I can access that bit. Cut out, join in longer section. At least until I can get it fixed properly.
     
  8. tommy8884

    tommy8884

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    Hello, I have patched in a new overflow pipe to stop the leak on the brick. There is still a slow drip, interestingly the drip is when the hot water is on.

    Anyway, QQ, a friend of mine has told me that the overflow pipe i have put in, should be flush with the brick and should not be sticking out as i have done it. Is that correct?
     
  9. HERTS P&D

    HERTS P&D

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    Your mate knows nothing! It needs to stick out!

    Andy
     
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  11. tommy8884

    tommy8884

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    update. Its not the cold water tank its defo the header tank and only drips when the hot water is heating or heating is on.
     
  12. oldbutnotdead

    oldbutnotdead

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    F & E tank (heating header tank) is overfull, when water warms up it expands, causing your dripping. Ballvalve probably weeping after being disturbed, new washer needed and needs doing sometime so the inhibitor in the system doesn't get diluted to uselessness.
     
  13. tommy8884

    tommy8884

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    Must be it thanks. Best way to get out the excess...open the drain down valve for a minute?
     
  14. oldbuffer

    oldbuffer

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    Bail it out with a bucket. Don't let it flow through the system or it will wash any crud in the tank into your system.
     
  15. fixitflav

    fixitflav

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    You need enough clearance between the water level when cold, and the overflow connection, to take up the expansion.

    Expansion between cold and hot is about 4% being generous, so for a typical system volume 100 litre, expansion ~ 4 litre. That's about 50mm rise in a typical F/E tank. If you have less than that the float arm needs adjustment.
     
  16. tommy8884

    tommy8884

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    I might be going nuts but there is no way the tank i have holds 100l. More like 20l
     
    Last edited: 6 Jul 2021
  17. SFK

    SFK

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    Nope - a normal sized bucket holds 14 litres:
    https://www.wickes.co.uk/General-Use+Builders-Bucket---14L/p/543007

    And as volume is a cube³, then it does not need much increase in size to get to 100litres.

    So more likley that your tank does hold 100l.

    100litres = 100,000cm³
    Cube root of 100,000cm³ = 46.4cm.

    So a tank of 46cm x 46cm x 46cm contains 97 litres
    and just to show how quickly the volume numbers go up, increase all three sides by only 1cm and
    A tank of 47cm x 47cm x 47cm contains 104 litres - it has got 7kg heavier!

    SFK
     
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