Run dedicated 3/4" pex to master shower?

Discussion in 'Shower & Bathtub Forum & Blog' started by ceiiinosssttuu, May 30, 2013.

  1. ceiiinosssttuu

    ceiiinosssttuu New Member

    Messages:
    11
    Location:
    Idaho
    I ran one 3/4" hot pex line to the master bathroom which serves a manifold that branches into five 1/2" pex lines. There are 3 fixtures plus 2 shower heads on pressure balancing valves. I don't want to have a pressure drop if both shower heads are going and someone turns on the hot water in the sink, for example. Should I run a separate 3/4" pex hot line that is just dedicated to the master shower? Is that necessary?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,183
    Location:
    New England
    The key is how much will be running at the same time. One 1/2" pex line feeding two showerheads is close to that tubing's max flow depending on the hot/cold mix. 3/4" pex is somewhat larger than 1/2" copper, and 3/4" copper is probably a good size for a bathroom group. If the pressure drops on the cold side (sink and someone flushes the toilet), that may be enough with 1/2" line to cause a pressure balance valve to throttle the hot side while it's also feeding the shower. Pex is good because it uses fewer fittings, and thus has less friction loss, but volume still depends a significant amount on ID, and copper beats it size-for-size.
  3. ceiiinosssttuu

    ceiiinosssttuu New Member

    Messages:
    11
    Location:
    Idaho
    Sorry I forgot to mention: I ran two 1/2" pex hots and two 1/2" pex colds to the dual shower. With 3 other fixtures in the bathroom besides these, do I have to worry about a pressure drop if someone uses the sink because the entire bathroom is fed by one 3/4" pex hot and one 3/4" pex cold? Or should I cap off the 1/2" hot lines to the shower and run a dedicated 3/4" pex line to the shower all the way from the 1" main in the mechanical room so it has all the volume to itself?
  4. Terry

    Terry Administrator Staff Member

    Messages:
    15,152
    Location:
    Bothell, Washington
    You are fine with what you have done.
    You did right by running 3/4" to the manifold, and then running 1/2" to each fixture. You're golden!
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