Low water pressure moen shower

Discussion in 'Shower & Bathtub Forum & Blog' started by Das, Sep 12, 2009.

  1. Das

    Das New Member

    Messages:
    8
    Location:
    san antonio tx
    I am new to this form. I'm scatching my head on this one, any help would be greatly appreciated.
    I have replaced a leaking moen cartridge and it worked fine for a few days. I pulled the cartridge out and ran it without a cartridge in it to remove any debri, there was no change. I have the same unit in the downstairs and exchanged the cartridges and had no change in pressure from either unit. I examined the inside of the valve. It looks clean. I removed the down spout and shower head, then blew it out with air and no debri was found.

    Anyone have any ideas? It's got me stumped. Thank you.
  2. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

    Messages:
    1,143
    Location:
    South*East
    If it was a Moen plastic stem you may have a peace of rubber from the old stem blocking the water passage. Try removing the new stem and have someone turn on the water. Just for a second or two. This should remove the upstruction. Try not to turn the stem when removing it.

    John
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,247
    Location:
    Cave Creek, Arizona
    water

    What kind of Moen valve? If you have a Moentrol, there is a balancing spool on the right side under the large trim ring, and that could be where you are losing pressure.
  4. Das

    Das New Member

    Messages:
    8
    Location:
    san antonio tx
    Thanks for answering johnjh201
    I got a oem moen brass stem. I flushed it with water and then isolated and flushed with air.
  5. Das

    Das New Member

    Messages:
    8
    Location:
    san antonio tx
    Thanks for answering hj
    I don't know which valve it is? It's the orginal 25, 28 years old, it looks in good shape. I have replaced the cartridge before and had no trouble and I have 2 of the same units in my house. I did look to see if there where any adjustments and there are none. Is there any good way to make sure I cleaned out valve and left no obstruction in it? I did it with water and air.I feel like I'm missing something simple:confused:
  6. C NUMB

    C NUMB Plumbing Contractor

    Messages:
    135
    Location:
    NPR, FL
    25-28yrs old, sounds like a standard moen valve, if both the screws for the faceplate are located directly below the valve handle it a regular non pressure balance valve. See if there are screwdriver stops on the valve body, if so, there may be build up in them. Try and remove to clean. You will need to shut the water down for the whole house before removing..
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,247
    Location:
    Cave Creek, Arizona
    valve

    The regular and Moentrol valves use the same unit so that does not tell you which you have, unless it is labeled on the trim ring. Take the round disc off and see if there is a large cap with a screwdriver slot at the right side of the valve body.
  8. Das

    Das New Member

    Messages:
    8
    Location:
    san antonio tx
    Thanks for answering C NUMB

    I'm pretty sure it's a standard valve. Orginal 28 year old track home. There are 2 screws under the valve handle. I will check to see if there are screwdriver stops. thx again
  9. Das

    Das New Member

    Messages:
    8
    Location:
    san antonio tx

    I'll check to see if there are any screws to adjust it. I'm pretty sure it's a regular valve with 2 screws on the bottom under the handle. Thx again hj.
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,247
    Location:
    Cave Creek, Arizona
    Moen

    There are NO SCREWS TO ADJUST IT. You are reading things into the replies which are nto there. You are looking for a pressure balancing spool which might need to be replaced if your valve has one.
  11. C NUMB

    C NUMB Plumbing Contractor

    Messages:
    135
    Location:
    NPR, FL
    hj, the screw placement in the Moentrol and Positemps are 1 at the lower left and one at the top right of handle. If memory serves me correctly these type valves came on the market close to 1990. The old moen valve (non-pressure balanced) trim with the 2 screws located blow handle with not fit a Moentrol valve body. Moen just came out a conversion kit to adapt new trim styles on the older non-pressure valve bodies.

    Here are a couple pictures:
    The old valve w/ screwdiver stops: Blockage maybe in the stop bodies

    [​IMG]

    The New Moentrol w/ screwdiver stops/ balancing spool:
    [​IMG]

    A cut detail of the Moentrol stop,spool,cartridge
    [​IMG]

    A Positemp w/screwdiver stops: Balancer is built into the cartridge
    [​IMG]
    Last edited: Sep 15, 2009
  12. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    Most times those spools can be soaked in a little vinegar to break them free and then cleaned with 1000 grit wet and dry sand paper and new O rings installed...the hard part can be getting the brass cover off the valve...

    Nice cut away view of the valve....
  13. Das

    Das New Member

    Messages:
    8
    Location:
    san antonio tx
    Hj thx for all the help, but almost 30 years is a pretty good run hehe and I need a working shower. So I took the jump and replaced it:)
  14. Das

    Das New Member

    Messages:
    8
    Location:
    san antonio tx
    c numb thx for the help, I went and replaced it almost 30 is a good run
  15. Das

    Das New Member

    Messages:
    8
    Location:
    san antonio tx
    Thx cass, but I took the leap and got a new one.
  16. master.legend

    master.legend New Member

    Messages:
    5
    Location:
    new jersey
    ok so I have been researching and reading this forum and I have this moen below. I just bought a short saled house where it was vacant for 8 months so the shower did not get any use. When i turned it on i get full cold but no hot at all! The rest of the house and even that bathroom sink gets hot water. So i researched and replaced the cartridge which thank god came out fully with all orings attached. I installed put back together and dam still no HOT water. So I came accross this post and was wondering what else I can do? Do I need to mess with that large screw which I guess is the balancing spool?I read about white vinegar but humm? So any answers guys??
    Thanks Louis
    The New Moentrol w/ screwdiver stops/ balancing spool:
    [​IMG]
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