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Discuss small leak cwst valve tail in the Valves & Taps area at

  1. dsgboy

    dsgboy New Member

    I wonder if someone can give a little pointer. I've drawn a bit of a ropey diagram so I can explain my problem. Having to fit a new 3/4 inch float valve to the cold water storage tank, and the original was in one piece, so removal had to be unscrewing the whole thing including the threaded tail into the three-way connector at point A.

    On fitting I added a fibre washer to point A, there did not seem to be one there before. I wrapped some ptfe tape and a little pipe dope on the end of the thread and hand tightened the threaded tail into point A.

    I then tightened the valve with nut D on the other side. I hoped that the valve and nut D would grip the threaded tail enough to tighten it into A further and stop the leak, unfortunately the valve and D seem to rotate without turning the tail. How can i grip the tail and tighten it without damaging the thread.

  2. lame plumber

    lame plumber Guest

    start again, tighten b and c nuts, take off the nut, clean off the ptfe and gunk, use a new fibre washer and gently tighten the nut without using ptfe and gunk, no leak should occur, end of lesson
    • Agree Agree x 1
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  3. Paulplumb

    Paulplumb Plumber GSR

    Hmm something doesn't sound right. Is there any chance of photos? In particular point A and this 3 way connector. Thanks.
  4. dsgboy

    dsgboy New Member

    I fear my diagram must have caused confusion, or I'm not understanding. the leak is at A outside the tank, therefore tightening a nut at D doesn't seem to help.
  5. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    may i ask are you from the usa ?
  6. townfanjon

    townfanjon Trusted Plumber GSR

    3/4 valve , is it a big tank ?
  7. dsgboy

    dsgboy New Member

    Thanks, I've added photos and labelled them to this post, which hopefully will make things clearer. The small leak is at A. I am in the UK, and it seems a fairly large tank. Used to be used for hot water system, but now combi boiler has bypassed it for hot water, only used in toilet/cold tap in bathroom.





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  8. Chriswareham

    Chriswareham GSR

    i think that you may have over tightened the joint and the fiber washer has split you can tighten nut d on to the ball valve this will stop it turning . grip the ball valve itself and then you can tighten the swivel nut (it shough not be overtighted to give a good seal) redo joint with new fiber washer or ptfe tape or hemp if its not a swivel and its a female iron to copper then you need to put ptfe or hemp on the threads of the ballvalve and retighten
  9. Best

    Best Trusted Plumber

    Sounds to me you basically have a female branch on a tee piece that the ballvalve tail screws into.
    If you put plenty of PTFE tape on the tail (+ paste if you want) and screwed it into a few threads, it should tighten very quickly if plenty of tape on it. Then just use grips on the threads to tighten it fully as it really won't matter to mark them. Another way to help seal the joint is to use a brass back nut also against the female fitting with PTFE to make extra seal.
    Edit, - your photos were posted after I had replied. Not much space there, so tighten the valve body well onto the tail and get the correct amount of PTFE on threads. Preferably use brass nuts to both sides of valve tail and keep the outer nut slightly back from the female branch and finally put a cord of PTFE in behind the nut and tighten it against the branch, then finally tighten the inner nut against the cwt.
    Remember if you had used enough PTFE tape in the first place, even hand tight until it gets too hard to turn by hand, would be leak free initially
    Last edited: Apr 19, 2017
  10. Paulplumb

    Paulplumb Plumber GSR

    Well it's no wonder you're struggling. You won't get that valve to tighten in there. I reckon you'd be better off chopping out that tee and fitting a swivel elbow.

  11. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    Is the pipe at the bottom of that tee 15mm? If so can you not change it for an angled isolation valve with a female connector on the end?
  12. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    Sorry mate. You sent this as I was typing my message:rolleyes:
    • Funny Funny x 1
  13. Chriswareham

    Chriswareham GSR

    turn off water undo botton nut undo top nut remove pipework from fitting remove from ballvalve put ptfe on threads of ballvalve retighten on ballvavle refit tpo pipe refit bottom pipe job done.
    • Agree Agree x 1
  14. Paulplumb

    Paulplumb Plumber GSR

    @dsgboy@dsgboy if you do chop out that tee and find you get water hammer you may have to install a shock arrestor elsewhere. Also you should really be installing a part 2 ball valve.
    • Agree Agree x 1
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