Leaky Joint Please Advise

Discussion in 'Plumbers' Talk' started by John2005, Sep 21, 2021.

  1. John2005

    John2005 Member

    Hi guys bit of an update. So I've redone the whole section. New copper pipe, new pressure fittings, removed all the PTFE tape from the pressure fittings. The pressure fittings and everythere is leak free except 1 spot. Between the the White dielectric and 1/2 to 15mm fitting.

    What I did to install was wrap 15 wraps of PTFE tape around thread, I put a smear of the jointing compound around it, screwed it all up, left it over night as per the instructions in the manual that suggestd 2-12hours so it had plenty of time. But still, sadly, a small leak from it. I'm starting to think the dielectric junction itself is just faulty...or something. Is there something I can replace that with ?
  2. pppmacca43

    pppmacca43 Screwfix Select

    How easy did the fitting screw together? If it went together quite easy I would try it with more tape, 20-22 wraps or even more. Sometimes threads are a bit loose and just need more tape. Don’t worry about waiting the 12 hours for the jointing compound, just put a bit in and turn the water in once u have it all reconnected.
  3. John2005

    John2005 Member

    Hmm, I think it had a bit of resistence but I'll try again. So glad I don't have to wait for the compound. If this doesn't work, is there something you would recommend that allows me to just get rid of this dielectric junction and replace it with another fitting without compromising anything?
  4. pppmacca43

    pppmacca43 Screwfix Select

    I would try that, and tbh if 22 wraps didn’t work I’d try more. No reason the fitting should be broken, if it was cracked I’d expect it to be fairly obvious
  5. John2005

    John2005 Member

    So I'm starting to think perhaps I damaged the thread from before when I in advertently overtigthened the compression fitting that was going into this dielectric junction because I've redone this about 10 times and the best I can get the leak to is one drop 5mins or so. Things I tried:

    1) Wrapped it with 22 wraps - It leaked after about 3-4mins (1 drip)
    2) Wrapped it with 25 wraps - It leakd after about 1-2 mins ( I musta did something wrong I guess?)
    3) Wrapped it with 30-33 wraps - It leaked after about 5-10mins (1 drip)
    4) Wrapped it with 40 wraps - It leaked after about 5-10mins (1 drip)
    Tried variations of with and without the jointing compound and variations of amounts

    All future attempts after 4th resulted in exactly the same thing. It's 99.9% sealed but after 5-10mins you start to see water very slowly pushing its way out between the dielectric junction and the compression fitting. Whilst the threads appear to be fine to me, I wonder if the threads are the issue perhaps? because I have no idea what to do now. Beyond trying to get a replacement dielectric junction or perhaps an alternative to the dielectric junction instead, It just refuses to seal! :(
  6. pppmacca43

    pppmacca43 Screwfix Select

    Wow 40 wraps it should seal with that, must have been very tight to do up? Maybe get in touch with the manufacturer and they could send u out a new one, not sure what else to suggest. You could try loctite sealing cord but to be honest if 40 wraps of ptfe doesn’t do it I doubt the cord will.
    Is it leaking on the plastic threaded joint, that the compression adaptor screws on to? The only other thing I can think of is to try a tap connector.
  7. terrymac

    terrymac Screwfix Select

    With that amount of wraps ,the PTFE tape is probably being unwound off.
    Does the length of the thread on the Di/elec reach to the bottom of the inside of the brass fitting ? If it does and both surfaces are flat ,fit a rubber washer .
    pppmacca43 likes this.
  8. John2005

    John2005 Member

    Yeah that's is where it has been leaking from, correct. And yeah 40wraps, didn't solve it either, I am convinced something is wrong with the plastic dielectric junction itself, whether it was my own doing from over tightening the compression fitting onto the plastic threads or whether it was a defect from the manufacturers. I'm unsure which... however I decided to try:

    And so far.... having fitted it - FINGERS CROSSED no leak so far...it's been well over 10mins. I've showered and come back and it's still dry. So...... I think we may have finally solved it! I didn't use any PTFE tape or jointing compound, just pushed the copper pipe into the 15mm side, tightened the other side onto the water heater outlet without the dielectric junction at all and so far, all good!

    Can I also just say, thank you so much @pppmacca43 and @terrymac for sticking with me on this problem, I really appreciate it having no body else I can ask these questions it's been massively helpful and thank you again :)
  9. John2005

    John2005 Member

    I did have a look at this earlier today and got oout my trusted box of washers unfortunately, I then realized that even with a washer it does not reach the bottom of inside of the brass fitting so that was a no-go sadly.

    I also wrapped the PTFE tape clockwise, and tightened clockwise to eliminate the possibility I was unwrapping as I was tightening and sadly out of the 1 billion attempts, I just never got it to seal. I'm convinced the threads or something were damaged somewhere not easily visable and this was causing the problem. :( looked for a replacement part of it, and it was £10 the part, and £6-7 delivery...so I opted to go TAP CONNECTOR route £3 for 2 and this SO FAR has fixed my leak! I'm so happy right now... but , I must wait and watch. Make sure it doesn't slow leak or something -_-
    terrymac likes this.
  10. pppmacca43

    pppmacca43 Screwfix Select

    Brilliant, I reckon u will have cracked it with the tap connector. I like those speedfit ones they are decent quality.
  11. Offshore

    Offshore Active Member

    Sounds like you have fixed it. If it is a parallel thread then no amount of tape or sealant will provide an effective, long term seal, the water will always find its way out eventually. I had a long argument with the plumbing assistant in B&Q about this when I encountered the exact same problem some years ago. A parallel tap connector fixed it permanently, despite his advIce to use thread tape on it.

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