1987 Moen Shower Valve

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by rcspott, Oct 14, 2020.

  1. rcspott

    rcspott New Member

    Joined:
    Oct 14, 2020
    Location:
    MT
    Just bought a home that was built in 1987. Shower has a Moen valve. When we use any other sink/water in the house shower water temp changes drastically. Can a new stem convert the valve to a Posi Temp/Pressure Control valve or does the whole shower valve need to be updated? Thanks
     
  2. KaeEdwardPlumbing.com

    KaeEdwardPlumbing.com In the Trades

    Joined:
    Oct 14, 2020
    Location:
    Sugar Land, TX
    Hello there,

    For clarification: I'm not certain what "water temp changes drastically" is meant to imply. Is this Hot water, or Cold water that you're losing?
    How many Fixtures do you usually turn on for this effect to happen & does it require your Moen Valve in use? Can you use other shower valves in your home without issues?
     
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  4. rcspott

    rcspott New Member

    Joined:
    Oct 14, 2020
    Location:
    MT
    While showering if someone else in the house uses water the temperature of the shower water changes. The water gets hotter if someone uses the kitchen sink. In 1987 had Moen come out with the pressure balanced valves?
     
  5. hj

    hj Moderator & Master Plumber Staff Member

    Joined:
    Aug 31, 2004
    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    The only way to tell if you have a malfunctioning one is to remove the large trim plate and look at the valve body.
     
    KaeEdwardPlumbing.com likes this.
  6. Terry

    Terry Administrator Staff Member

    Joined:
    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    In 1987 you most likely have the old Moen valve that was not balanced. I would replace the valve, not the cartridge.
    In my mothers home I replaced all three. Nothing worse than standing in a 36" x 36" shower while someone uses the kitchen sink in the other room, cold, hot, cold, hot. Nope! I'm replacing this with something pressure balanced.,

    Without touching the shower valve, you can make sure there is an expansion tank for your home. That also helps with pressure drops.
     
    Last edited: Oct 15, 2020
    Jeff H Young likes this.
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