Moen Posi-Temp, Low Flow at tub spout

Discussion in 'Shower & Bathtub Forum & Blog' started by Jsmallberries, Feb 13, 2019.

  1. Jsmallberries

    Jsmallberries Member

    Joined:
    Nov 2, 2015
    Location:
    Zephyrhills, Florida
    20 year old, single handle Moen, turn not pull, shower tub combo.

    Hot or cold or combined, low flow from tub spout, and the pressure lessens even more within 30 seconds or so after running the water.

    The main flow throughout the house is somewhat low, but this is worse here and most likely a separate issue.

    Would a clogged or defective shower stem cause this? Or what should I look for?
     
  2. Terry

    Terry Administrator Staff Member

    Joined:
    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    Has it always been low or is this recent?

    If recent perhaps the cartridge. Moen Posi-Temp
     
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  4. Jsmallberries

    Jsmallberries Member

    Joined:
    Nov 2, 2015
    Location:
    Zephyrhills, Florida
    Per distressed neighbor, recent problem. The whole house has fairly weak pressure, but this location is really bad.
     
  5. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    Get a water pressure gauge with a garden hose thread (GH /GHT). They are pretty cheap and available.

    Connect it to the WH drain valve, and turn on the drain. Run hot water and see what the pressure does. If the pressure drops a lot, the pressure drop is on the way to the WH. You would first check that the valve for the water heater water was fully open. Then you might suspect the heat trap on the way in.

    If the WH pressure stays up pretty well as you run hot at the shower, then the blockage is on the way out. There is a heat trap there too.

    Also try your gauge on a cold tap to make sure the problem is for hot only. Outside faucet, or a laundry tap is good.

    You can watch the hot pressure at the laundry while somebody runs the shower. If that stays up, then the restriction is after the hot water splits off between the bathroom and the laundry area.

    [​IMG]
     
    Last edited by a moderator: Feb 14, 2019
  6. Jsmallberries

    Jsmallberries Member

    Joined:
    Nov 2, 2015
    Location:
    Zephyrhills, Florida
  7. Jsmallberries

    Jsmallberries Member

    Joined:
    Nov 2, 2015
    Location:
    Zephyrhills, Florida
    So I replaced the Moen valve stem, now has very good pressure and the shower handle turns effortlessly.

    Was a bitch to get out, 19 years, but they have a softener installed, really hard water here, my own replacement, pulled the guts out leaving the casing fused in the valve body, that was an experience....

    My question, the plastic piece that comes with the replacement doesn't work, as the tabs from the old cartridge are recessed into the shower valve body. I had to cut them off so it would turn. I did that and used a danco puller, went back and forth between the two, finally got it to turn.

    Not sure I would do that again for someone, as the risk of failure is pretty high with these
     
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