Connecting Plastic Fittings to Copper

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by tonyn1, Nov 14, 2007.

  1. tonyn1

    tonyn1 New Member

    Messages:
    30
    Location:
    Indiana
    I'm just installing a water softener which has a plastic, which I believe is nylon, valve. I ran 3/4 copper lines down to it on which I installed a 3/4 x 1" threaded female copper fittings. I put teflon tape on the male plastic fittings and installed. When I turned the water back on, I noticed some drips coming out of the connection. I tightened the fittings some, careful not to over tighten and break the plastic fittings. Checked again and still had some leakage so I went to pipe sealant and thought I had it licked, but I still have a very small amount of leakage. I don't want to tighten more as I'm afraid I might break the plastic fittings. Suggestions?
  2. frenchie

    frenchie Jack of all trades

    There's not a rubber washer involved in this assembly, is there? If there is, you oughtn't use teflon.

    Oustide of that possiblity... I got nothing.

    Wait for the pros...
  3. tonyn1

    tonyn1 New Member

    Messages:
    30
    Location:
    Indiana
    No rubber involved.
  4. frenchie

    frenchie Jack of all trades

    The pros will be along shortly.
  5. tonyn1

    tonyn1 New Member

    Messages:
    30
    Location:
    Indiana
    Where are they? Still waiting.
  6. msgale

    msgale New Member

    Messages:
    90
    Location:
    Ohio
    cannot use adapter to join copper and plastic

    they expand at different rates,
    Also, if the female plastic is overtightened it willsplit at an inopportune time.

    you need a compression fitting, one side copper ferrule to over copper tube, other side plastic ferrule to go over a pvc or cpvc tube. then each is tightened, and it will not leak ever.

    or, there are transition fittings that use rubber washers, for connecting metal to plastic.
  7. Terry

    Terry Administrator Staff Member

    Messages:
    15,050
    Location:
    Bothell, Washington
    If you have a plastic male adapter going into a female copper fitting, and you have used Teflon Tape, it should work if it's tight enough.
    Sometimes plumbers use a little thread sealant over the Teflon tape too.

    It sounds like you are doing the right thing.
    It's hard to tell someone how tight to do these thing though.
    My tight, may be different from your tight.
  8. Herk

    Herk Plumber

    Messages:
    547
    Location:
    S.E. Idaho
    A lot of softeners come with a special nut that fits on the plastic thread and has a copper stub that needs to be soldered to. If you had that type, the thread would no be tapered and would not be designed for a threaded fitting.

    [​IMG]
  9. tonyn1

    tonyn1 New Member

    Messages:
    30
    Location:
    Indiana
    I don't have the type of fittings you are talking about. However, I did solve my problem. I think the problem was I was using a cheap grade of teflon tape. It was too thin and was getting torn up when I screwed the fitting in. I found some "Blue Monster" brand that is a bluish color and advertised as professional density. I made sure I put plenty on and then applied a thin coat of sealant also. It seems to have done the trick. Thanks everybody for the help.
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