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Thread: pex or copper between valve and tub spout

  1. #1

    Default pex or copper between valve and tub spout

    i have heard that using pex pipe between the tub/shower valve and the tub spout may be a bad idea, as it may cause water to go out the shower when unwanted. not sure why, unless the elbows for pex being on the inside cause a restriction.

    also do newer valves account for this in any way ?

    trying to avoid soldering (i.e. using copper).

    planning to use pex from the valve to the shower head.

    Also have heard that the distance from valve to tub spout s/b between 11" and 18". is this just about esthetics or are there technical reasons ?

    thanks.

    mike

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    1/2" copper verses 1/2" pex have the same external dimensions, but the internal dimensions are different pex pipe walls are thicker, thus smaller and lower flow capacity. Any restriction to the tub spout will often be enough restriction to cause it to slowly backup in the showerhead riser, and dribble out there as well. Plus, there isn't a good way to attach any of the tub spouts to pex. They typically are either a slip on or a screw on connection. You can't anchor the pex, so your spout would move and the connection would be a problem. Pex up to the valve is okay.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    Moderator & Master Plumber hj's Avatar
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    Default pex

    If the distance is greater than that it could also induce enough back pressure to force water out of the shower head. Shorter than that has no problems.

  4. #4
    DIY Senior Member Livin4Real's Avatar
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    Just ran all mine with pex after speaking with a couple pros that use it frequently. There are drop ears out now that are made for attaching the tub spout and shower head to pex. They are 1/2" pex to 1/2" fip and have three screw holes in them to attach to the studs/walls, etc. I used a 2"x4" cross member in between the studs to screw the drop ear to, then used 1/2" mip hex nipple to screw into the drop ear and then screw on the tub spout. It's solid and won't move at all. I just made sure that all of the crimp area was exposed past the top edge of the cross member on the drop ear so I could get my crimper around it. For the shower head use the same drop ear and cross member method, just screw your showerhead pipe straight into the drop ear. The showerhead drop ear I have flush with the back side of the drywall so the pipe goes into the drywall a little to hide all the threads and the spout nipple I have the hex part sticking just past my shower insert because my delta faucet has plenty of room to screw it onto the nipple 2" if need be. I'll try and get some pics.
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  5. #5

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    thanks for all the responses; much appreciated. i will look into those drop ears - i'm a bit leary now of the pex, after running into a guy at the home depot who had the shower rise issue, and the Delta help desk told him to go back to copper. tried to get some info from Moen, but couldn't get thru. i will look into those drop ears.

  6. #6
    Moderator & Master Plumber hj's Avatar
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    Default Pex

    The problem with PEX is the pipe between the valve and spout, NOT the fittings or loose ell. A drop ear elbow is need regardless of the material, but it will not eliminate the back flow problem if you use PEX. Maybe the customers of the pros who "use it frequently" only use the tub as a shower so they do not have the problem.
    Last edited by hj; 10-27-2007 at 08:39 AM.

  7. #7
    DIY Senior Member Livin4Real's Avatar
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    We're several baths into it with kids and no dribbling from the showerhead. My spout is stubbed at 24", valve at 42" and showerhead at 81".
    Last edited by Livin4Real; 10-28-2007 at 06:52 AM.
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  8. #8
    DIY Senior Member Livin4Real's Avatar
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    I have a Delta Monitor as well.
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