Cold supply from 1" and hot from 3/4" to feed a large spa shower?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by MACABUS, May 5, 2014.

  1. MACABUS

    MACABUS New Member

    Messages:
    6
    Location:
    Arizona
    I'm plumbing a large spa shower that has 3/4" supply lines. The 1" main comes into the house through the bathroom wall, and I'm wondering if there would be an advantage to tapping into it for the cold supply.

    Would this create more overall volume for the shower fixtures? Could it cause any problems?

    The setup is a 3/4" thermostatic valve, feeding six 3/4" volume controls. There are six WaterTile body sprays, a large rainfall shower head and a hand sprayer. There are also 3 pressure balancing loops.
    Last edited: May 5, 2014
  2. Terry

    Terry Administrator Staff Member

    Messages:
    14,759
    Location:
    Bothell, Washington
    It never hurts to go with with the cold supply.
    Though most of your water will be coming from the hot side. With six body sprays, you will need to keep the sizing on those. What do you have for water heating?
  3. MACABUS

    MACABUS New Member

    Messages:
    6
    Location:
    Arizona
    Thanks Terry.

    I'm using a GE SmartWater electric 50 gal. water heater. It's 20' from the shower and on the same floor.

    If you don't mind, I would really appreciate your input on the attached schematic.

    Attached Files:

  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,802
    Location:
    New England
    Turn everything on, and you'll get about 5-minutes of hot water...better make the showers quick! WHen you install a human car wash equivalent, you need industrial sized hot water sources, too.
  5. MACABUS

    MACABUS New Member

    Messages:
    6
    Location:
    Arizona
    Point taken.

    Unfortunately, I don't have the space for a larger tank, and it would be prohibitively expensive to re-wire the laundry room for a tankless heater.

    On the bright side, I live in Phoenix and the source water is lukewarm most of the year.
  6. ankhseeker

    ankhseeker Member

    Messages:
    78
    Location:
    California
    Don't know if you have any water treatment/softeners, but that would be bypassed if you tapped into the cold main.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,245
    Location:
    Cave Creek, Arizona
    Those green and black "balancing loops" are just "busy work" and serve absolutely no useful purpose.
  8. MACABUS

    MACABUS New Member

    Messages:
    6
    Location:
    Arizona
    I've heard mixed reviews about balancing loops. Kohler recommends them, but I may do without.

    Another question for you: Would it be advisable to feed off the lower outlet of the thermostatic stack valve and pipe back up to a 1" tee line that would feed each of the 3/4 volume controls?
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,245
    Location:
    Cave Creek, Arizona
    It appears that your themostatic valve has a volume control build in on the top. THerefore, if you connect the other controls to the bottom, you would NOT have to turn on two valves when you wanted to take a shower.
  10. MACABUS

    MACABUS New Member

    Messages:
    6
    Location:
    Arizona
    Thanks for that.

    The Kohler valve has an output of 14.5 GPM on the top and 17.2 on the bottom. I was thinking of running the rainshower head and top two WaterTiles from the lower supply AND the other fixtures from the top – for maximum volume.

    I talked to Kohler about this and they said no way! Apparently, there can be a 10 degree water temperature fluctuation between the top and bottom outputs. Does that sound right to you?
  11. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,245
    Location:
    Cave Creek, Arizona
    Grohe says the same thing, but logically I cannot see it happening.
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