3/4" or 1/2" to shower valve vacinity

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by cruiser, Jul 29, 2014.

  1. cruiser

    cruiser Member

    Messages:
    46
    Location:
    California
    Hello all,

    I'm in the planning stages for a new double shower and am currently thinking water supply. It's a ranch style with concrete slab. The nearest current stub outs are 16 feet away (8' across the loft and 8' down the wall). There are 3/4" stubs and 1/2" stubs available to me at pretty much the same location
    Should I pull 3/4" as near to the control valve as possible and then reduce to 1/2" or just take the 1/2" from the stub and run it all the way?

    Thanks for your time
  2. Terry

    Terry Administrator Staff Member

    Messages:
    15,298
    Location:
    Bothell, Washington
    Shower heads run at 2.5 gallons a minute.
    You can run two heads on 1/2" easily enough.
  3. cruiser

    cruiser Member

    Messages:
    46
    Location:
    California
    Thank you Terry. I had been trying to convince myself otherwise :)
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,047
    Location:
    Cave Creek, Arizona
    What kind of pipe are you using? That will determine which size you should use.
  5. Earl

    Earl New Member

    Messages:
    17
    Location:
    El Segundo
    When I did my kids bathroom bath/shower I used 1/2" copper for an approximate 8' length. Although the flow is fine, I did end up with a high pitched whine when in use. I read somewhere and believe this might be due to a combination of the smaller 1/2" pipe and a small protrusion of solder forming on the inside of the pipe as it turns 90 deg into the valve (not sure whether it is the cold or hot side). Only a theory since I really can't explain the phenomena. It's been there for many years so it can't be residual air in the pipe.

    When I did my master bathroom I ran 3/4" all the way up to the shower valve with no similar problem. The master bath also has two other valves for an overhead shower and a rear mounted shower. One side benefit is that there is less pressure drop in 3/4" pipe vs 1/2". However for 8' that difference is very small.

    In any case, I may be wrong to blame the pipe size but if I had to do it over again I’d run ¾” in the kids bath/shower.
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