Threaded union to shower valve

Discussion in 'Shower & Bathtub Forum & Blog' started by richp, Aug 6, 2014.

  1. richp

    richp New Member

    Messages:
    5
    Location:
    NJ
    I know that it's not the best solution, and that soldering the pipe is the preferred method, BUT...
    I just installed a Kohler shower valve for a bath remodel, and used a threaded union to connect hot/cold supply (mostly due to the ability to do most soldering separately and just wrenching the assembly in place, as well as tight quarters). This wall will be covered in the very near future.
    While it would be possible to cut it out and solder everything in place, i would rather not do it, and it does not leak at all.
    Is there any compelling reason (code, durability) for me to go thru the trouble of changing all of this out?

    Attached Files:

    Last edited: Aug 6, 2014
  2. Terry

    Terry Administrator Staff Member

    Messages:
    15,283
    Location:
    Bothell, Washington
    There is no compelling reason to change that. There have been plenty of tub and shower faucets installed with unions.
    SHR likes this.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,021
    Location:
    Cave Creek, Arizona
    Absolutely not. That is just a variation on how tub/shower valves have been installed for decades.
    SHR likes this.
  4. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    Messages:
    4,683
    Location:
    North Vancouver, BC
    Personally I like the threaded unions better - less chance of damaging the cartridge if the plumber leaves it in while installing.
  5. richp

    richp New Member

    Messages:
    5
    Location:
    NJ
    Thanks guys, just second guessing myself.
    As a hobby-remodeler, I kept reading that many people are strictly against using any type of unions in a concealed space. That made me question the longevity/stability of the connection.
    Up goes the sheetrock!
  6. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    Messages:
    4,683
    Location:
    North Vancouver, BC
    Keep that sheet rock out of the tub/shower surround.

    Have you planned for any shower niches?
  7. richp

    richp New Member

    Messages:
    5
    Location:
    NJ
    That's not sheetrock, it's Hardibacker.
    No niches, gonna have just a soapdish to keep it clean looking.
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,262
    Location:
    New England
    Don't let John throw a big wet blanket on your plans. While drywall by itself is NEVER a good idea in a tub/shower area IF it can get wet...IF you use something approved for use over it that has been tested and approved to meet the ANSI A118.10 waterproofing spec AND you install it properly, it is as water-tight and reliable as any other method. There are a few big IF's there, and failing one of them can be disastrous. At least two substantial companies specify and have tested their waterproof membranes for use over drywall (and other materials). Using a cbu gives it a chance if you mess up. But, you have the same problem with the drywall around your windows, doors, and ceiling...if your roof fails, or your window or door isn't installed properly, you'll have problems but that doesn't stop people from using drywall there and it shouldn't in your tub/shower, but YOU MUST INSTALL IT PROPERLY!
  9. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    Messages:
    4,683
    Location:
    North Vancouver, BC
    Your threaded unions did not end up looking like these did they? Here you see I think a dry fit since no evidence of teflon tape or pipe joint compound (pipe dope) can be seen.


    [​IMG]

    I see your photo now better.

    [​IMG]


    Have you installed poly over the studs and lapped the tub tiling flange? Does not loo like it from this photo?


    Any plans of using a topical waterproofing? Something like Hydro Ban? Ardex 8+9? NobleWall Seal?
    Last edited: Aug 7, 2014
  10. richp

    richp New Member

    Messages:
    5
    Location:
    NJ
    Oh, I see the misunderstanding now.
    When I said "Up goes the sheetrock", I meant that I would be covering the wall behind the valve.
    The tub surround is Hardi (up 5'), and I will be waterproofing it with Redguard. The rest of the bathroom is all greenboard.
  11. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    Messages:
    4,683
    Location:
    North Vancouver, BC
    I'm not a fan of Hardi Board. I would recommend you tape all the seams with a mesh tape and thin-set. Something modified like MegaLite or MegaBond. Then once this is dry use the RedGuard.

    RedGuard bonds better to thin set than it does HardiBacker.

    If it's not to late I would switch to Hydro Ban. Then you could use some of their banding and pipe connectors. Your install appears to have no poly between the lower course of cement board and the tub lip. This is the weakest link.
  12. richp

    richp New Member

    Messages:
    5
    Location:
    NJ
    Pipe dope (Megaloc) and tape.
  13. penobscotman

    penobscotman Member

    Messages:
    30
    Location:
    Buffalo NY
    Do you mean a union between the female adapter (screwed to the valve) and the supply line, or to attach the female half of the union directly to the valve in place of an adapter?

    I've got a leak between the female adapter and the valve -- looking for a solution. I must have been afraid of over-tightening the adapter.
  14. SHR

    SHR Member

    Messages:
    127
    Location:
    Minnesota
    Common DIY problem. You did not make the threaded connection correctly. Cut it out, clean the threads, re-do the connection using pipe dope and/or PTFE (used to be called Teflon) tape and screw your female adaptor on it really tight. Re-connect the pipe with a coupling and you will be all set.
  15. penobscotman

    penobscotman Member

    Messages:
    30
    Location:
    Buffalo NY
    "Common DIY problem" -- that stings! But you are right, of course. I was too timid with the wrench. I cut out adjacent copper, reinstalled new adapters and really torqued them down. Now no leaks. It was easier to apply force the second time around as the valve was held firmly by the plumbing still in place. I found it hard to get the adapters really tight holding the valve in my lap or on a bench.

    Thanks for the help!
  16. SHR

    SHR Member

    Messages:
    127
    Location:
    Minnesota
    You are welcome. My statement was not meant to dis-respect you or your plumbing know how. I had a friend call me to troubleshoot the 3 out of 4 leaking connections on a new shower valve he and a neighbor installed. He always likes to show off how "handy" he is and I always end up fixing the problems. All 3 connections had used female adapters that just were not tight. I cut them out and correctly re-installed them - no more leaks. You have alot of company with not getting your threaded adapters tight enough. Lesson learned, fixed and all good now. I am glad it worked out for you.
  17. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,262
    Location:
    New England
    The quality of some of the fittings available, especially at some of the big box stores, is likely part of the problem with threaded connections these days. Some of them are rolled threads, some are cut, many of them are made in China, and the size, depth of the thread, and their quality are often less than desired with improper depth, taper, length, OD, etc. In this case, a good dollop of pipe dope is likely to seal things better than the tape which won't conform over tears in threads or improper taper, or other manufacturing deficiencies. SOme people use both the tape and pipe dope. Keep in mind that it is the compression of the filler (the tape or pipe dope) between the threads that makes the seal, and it works best when it is manufactured properly. Dope fills in the imperfections better than the tape.
  18. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,021
    Location:
    Cave Creek, Arizona
    quote; All 3 connections had used female adapters that just were not tight. I cut them out and correctly re-installed them - no more lea

    If they used female connectors, the the odds were good that they were "multi use" connections and the tubing would have soldered directly into the valve without adapters, which is how most plumbers would have installed it.
  19. SHR

    SHR Member

    Messages:
    127
    Location:
    Minnesota
    Thank you for the comment hj. That is how I ALWAYS do my installs, but here I was just repairing my friends mistakes without using any more pipe.
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