Revised Routing of copper pipe to tub/shower valve

Discussion in 'Shower & bathtub Forum & Blog' started by FJK, Jan 6, 2008.

  1. FJK

    FJK New Member

    Messages:
    73
    Location:
    Illinois
    I'm going to install a new tub/shower valve (Moen posi-temp) in place of my non-balanced pressure 30 yr old Moen valve. The bathroom walls are opened up to the studs. The way the old, existing copper piping was roughed-in seems kind of bush leauge. I'll try to explain.. the bathroom is on the 2nd floor & the bathroom that I'm redoing is back to back to a 2nd hall bath on the 2nd floor. So, the copper pipe comes up from the lower level, through sole plate of the interior wall, extends up ~ 12" from the floor, & the starts running horizontally through wall studs. When it gets to the tub/shower valve, the copper piping runs up to the valve, and then about 12" of water hammer piping runs up from the valve & dead heads. IOW, the valve is feed from the bottom. In additon, the cold water supply is Tee'd to supply water to the toliet in the bathroom on the other side of wall. Finally, there is a 1-1/2" vent pipe in the same stud cavity as the shower valve, Bottom line, very hard to unsolder old shower valve & solder in new valve.

    What I want to do is solder in copper pipes into the new valve going up, eliminate the water hammer pipes, run to the next stud cavity, come back down, & connect into the existing plumbing. I would have enough "swing" in the new pipes to connect to the existing piping. Further, both water supply pipes would effectively be above the shower head. I would think this would stop the whistleing sound I got with the old shower valve & plumbing.

    So, I would basically be feeding the shower valve from the top down, rather than from the bottom up. Does this sound correct? Does it even matter?

    All of you guys have been really great in answering my earlier questions.

    Thanks very much, FJK
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,636
    Location:
    Cave Creek, Arizona
    valve

    You are going to do a lot of extra work that will not have any effect on the final operation of the valve. If the water pipes come from under the floor then we feed the valves from the bottom. But we would NEVER run them up, over, and then down again, unless there were building/structural reasons for doing so. The whistle is either the valve or the shower head, not the piping.
  3. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego

    That sums it up/

    I would add that air chambers are not condsidered to be acceptable hammer arrestors. Hammer arrestors are not usually needed on a shower.
  4. FJK

    FJK New Member

    Messages:
    73
    Location:
    Illinois
    Thanks for the reply Jimbo:
    The reason I'll still probably run up, over, & back down is a space problem with that vent pipe. Whoever did the orignial installation scorched the plastic pipe. There is just not enought pipe "swing" availabe to make final installation of the new valve to the exisiting plumbing. Maybe a pro could do it, but I know my limitations. Thanks for your knowledge. FJK
  5. Nate R

    Nate R New Member

    Messages:
    472
    Location:
    Milwaukee, WI
    Where do hammer arrestors usually go? Washing machine lines, and what else? Toilets and DWs? Is that it?
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,009
    Location:
    New England
    Quick closing (normally) solenoid controlled valves can generate a water hammer. Most manually controlled valves just can't be closed quick enough to create a problem. Some toilet valves can, but most do not. A simple air chamber will fill up with water in a few months, and become useless. If you are going to do this, use one of the manufacturerd chambers that uses a seal between the air and the water - it has a chance of lasting for quite awhile.
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