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Thread: redo pipes behind tub wall

  1. #1

    Default redo pipes behind tub wall

    My current tub is the one piece tub/surround. I'd like to change it to tub and tile the surround. It turns out I'll need to redo all the copper pipe connections and valve body behind the wall.

    Questions:
    1) what type of copper pipes should i use ("L" or "M") ? If uncertain, maybe i should just take an existing piece out and match ?

    2) the inlets/outlets of new valve body (Price Pfister) are threaded. According to instruction, i should use pipe nipples and pipe unions between copper pipes and valve body. For spout and shower head pipes, i should use drop elbows. What material (brass ? ) should I use for pipe nipples/unions/elbows ? Are there different materials ?

    3) spout pipe niple must project 3 7/8"- 4" from the finished wall. Center of valve body outlets to finished wall should be around 3". What length of pipe niple should I use here (looks like should be around 6 1/2" - 6 7/8") ? I need to take into account the elbow and how much the pipe nipple is threaded into the elbow .... Is there a rule of thumb to estimate that ?

    Thanks !!!
    Last edited by mf915; 03-04-2007 at 06:30 AM.

  2. #2
    Commercial Plumber markts30's Avatar
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    Default

    Quote Originally Posted by mf915
    My current tub is the one piece tub/surround. I'd like to change it to tub and tile the surround. It turns out I'll need to redo all the copper pipe connections and valve body behind the wall.

    Questions:
    1) what type of copper pipes should i use ("L" or "M") ? If uncertain, maybe i should just take an existing piece out and match ?

    2) the inlets/outlets of new valve body (Price Pfister) are threaded. According to instruction, i should use pipe nipples and pipe unions between copper pipes and valve body. For spout and shower head pipes, i should use drop elbows. What material (brass ? ) should I use for pipe nipples/unions/elbows ? Are there different materials ?

    3) spout pipe niple must project 3 7/8"- 4" from the finished wall. Center of valve body outlets to finished wall should be around 3". What length of pipe niple should I use here (looks like should be around 6 1/2" - 6 7/8") ? I need to take into account the elbow and how much the pipe nipple is threaded into the elbow .... Is there a rule of thumb to estimate that ?

    Thanks !!!
    1- Type L (M is too thin)

    2- You can use brass nipples for the valve body but I would probably use copper male adapters and some pipe. (Prefer soldered joints to threaded in a wall)
    Avoid unions...

    3- get a 6" nipple and cap for now - install everything and test it (make sure drop-eared 90s are anchored well...)
    Prior to covering everything with the board and tile, loosen the nipple a little at the 90...
    After the tile is done, mark the nipple with marker where it meets the wall and remove it.
    Measure the nipple part in the wall and add your 4".
    Go and buy a brass nipple that long and screw it into the 90 in the wall using teflon tape and pipe dope...
    No figuring and worrying - just the perfect nipple length...

  3. #3

    Default

    Thanks for the reply. Just came back from Home Depot...

    #2 - I see they have copper male adaptor (one threaded end, the other end for soldering). This is a lot cheaper than using union + nipple. So I like this option The only concern i have is....after putting everything together, if water leaks through the threads, I cannot tighten it anymore. I will probably have to cut the copper pipe again. Is this kind of male adaptor meant to go directly to the valve body ? If it's okay, use teflon tape + pipe dope ?? How tight ?

    #3 - home depot has brass nipples only in 1" increment (1", 2",... 6"). Where can you get brass nipples at any length you want ?

    thanks !!

  4. #4
    Commercial Plumber markts30's Avatar
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    Quote Originally Posted by mf915
    Thanks for the reply. Just came back from Home Depot...

    #2 - I see they have copper male adaptor (one threaded end, the other end for soldering). This is a lot cheaper than using union + nipple. So I like this option The only concern i have is....after putting everything together, if water leaks through the threads, I cannot tighten it anymore. I will probably have to cut the copper pipe again. Is this kind of male adaptor meant to go directly to the valve body ? If it's okay, use teflon tape + pipe dope ?? How tight ?

    #3 - home depot has brass nipples only in 1" increment (1", 2",... 6"). Where can you get brass nipples at any length you want ?

    thanks !!
    #2 - Oh Oh - this might start up the discussion about soldering threaded connections again...LOL.
    I am sure others will chime in soon...
    Solder the MIPs onto pieces of copper pipe and then, after making the connection to the valve (with Teflon tape and dope), wrap with a damp cloth to keep the heat from getting to the valve when you solder the rest of the piping...(you should also take the guts out of the valve for good measure while doing this..)

    #3- You can get the brass nipples in a wider variety of sizes at any good plumbing supply house... (usually in 1/2" sizes)

  5. #5
    Retired Defense Industry Engineer jadnashua's Avatar
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    Many of the valves with threaded connections will actually accept the pipe directly internally as if it was a fitting, so you don't have to use the threaded connections if you don't want to. Since the valve body is thicker and has more mass than a typical fitting, you will have to heat it longer to make the connection.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  6. #6

    Default

    Thanks for the suggestion.
    Since I'm not a pro, I would not try to solder anything directly into the threaded holes of valve body. If I messed up, the expensive valve body would become useless.

    I would solder a piece of copper pipe to the adaptor first. Then add teflon + pipe dope before attaching the threaded end of the adaptor to the valve body. Just pray that I get a good leak-free connection. Then repeat that 4 times !! Will be careful when soldering pipes close to the valve body.

    If you guys have other good suggestions, please let me know !!

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