Low Pressure mystery

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by dpw-ct, Dec 3, 2012.

  1. dpw-ct

    dpw-ct New Member

    Messages:
    16
    Location:
    New York
    I have just installed a new bathroom and am disappointed by the low pressure in the stall shower. Wondering what might be wrong. There does not appear to be any clog or low flow device in the shower head.

    -- I have a private well with pressure tank
    -- Shower is approx 28 vertical feet from the well tank in my basement.
    -- Pex home run to manifold 1/2 inch to bathroom
    -- Mixing valve is Rohl HY19BO
    -- 1/2 copper from mixing valve to shower head and hand shower (have a shut off for each - and we have low pressure even when just one is in use)
  2. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,185
    Location:
    NW Ontario, Canada
    You don't say what pressure you have at the tank but you will lose 12 PSI over that height alone plus whatever losses through line resistance. Add to that, modern showers are mandated by legislation to be low flow.

    You might consider raising the pressure at the tank.
  3. dpw-ct

    dpw-ct New Member

    Messages:
    16
    Location:
    New York
    Thanks for the quick reply. The switch is 30/50 I checked the pressure gauge on the well tank it is reading 50 psi. Do you think I need to raise the pressure or could there be another explanation. If I should raise it can you tell me how to go about that.

    Thanks



  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,313
    Location:
    New England
    There are two adjustment screws on most well pressure switches....one adjusts the max and the other adjusts the spread...or, you could swap the pressure switch for say a 60/40 that is already adjusted.

    Today's valves and showerheads tend to be lower flow than the older ones. 1/2" pex is closer to 3/8" copper, but still should provide more volume than needed for ONE showerhead.
  5. dpw-ct

    dpw-ct New Member

    Messages:
    16
    Location:
    New York
    would I need to adjust the air on the tank as well?
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,247
    Location:
    Cave Creek, Arizona
    "low pressure" is a subjective evaluation. Use a gauge to get the "real" and exact pressure, then we can tell you what, if anything, to do.
  7. dpw-ct

    dpw-ct New Member

    Messages:
    16
    Location:
    New York
    Thanks will do - any heads up on what pressure reading would be good?
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,313
    Location:
    New England
    Most valves are designed to work with a minimum of 30-40# or so (some lower). Now, that doesn't mean you'll love their operation at that pressure, but that they'll work. Most people are satisfied with 40-50#. Codes require it to be limited to 80psi - higher and it could just shoot a glass out of your hand when filling it at the sink!
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,247
    Location:
    Cave Creek, Arizona
    The pressure should be close to what it is coming into the house. IF both are almost equal and BOTH are low, then you have an external problem, especially if it starts high and then drops to low.
  10. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,185
    Location:
    NW Ontario, Canada
    Are you forgetting to account for the 28 feet of rise at .43 PSI per foot?
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