Water Hammer knock - DANCO?

Discussion in 'Shower & bathtub Forum & Blog' started by WorthFlorida, Oct 28, 2009.

  1. WorthFlorida

    WorthFlorida Member

    Messages:
    108
    Location:
    Lake Worth, Florida
    I just replaced a Moen Posi-temp cartridge with a Danco replacement. The original problem was the hot water side just suddenly would only trickle out and the cold water side was fine. The valve body has the shut off valves and the hot water side turns 360 degrees and it had no effect on the water pressure and the cold water side only needed a 1/4 turn to turn off.

    It was quite a job getting the old Moen cartridge one out. I made a jig to pull it out and then a pair of pliers to do the rest but it still did a little damage to the cartridge so I had to buy one. Before I put the new Danco unit in I turned on the water to flush out the valve body and the hot water side just seems not to work at all as far as shutting off the hot water. I put the new cartridge in and the hot water now flows as expected but a new problem has arise. When the water is turned off or even on at any faucet in the bath room, you hear a knock from the shower faucet. I remove the cover plate and the pipe is not hitting or rubbing on anything. I drained the system to get air into the anti-knock pipes installed at the shower faucet.

    It sounds like a water hammer knock (two knocks) but it did not have this problem before the cartridge changed out. If I place my hand on the shower valve body you can feel it. It also makes the knock noise when the shower faucet is turned off.

    I'm asking if anyone ever had a problem with a Danco valve where it design is causing something inside of it to move when the water pressure changes?
    Last edited: Nov 4, 2009
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    We prefer OEM parts, but Danco is probably better quality among the aftermarket stuff.

    I suspect your problem is related to the check stop and not the cartridge.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,519
    Location:
    Cave Creek, Arizona
    valve

    IT is probably the pressure balancing spool in the valve reacting to the imbalance when you open a faucet. Call 1-800-BUYMOEN and have them send you an OEM cartridge.
  4. WorthFlorida

    WorthFlorida Member

    Messages:
    108
    Location:
    Lake Worth, Florida
    I finally got around to it and I changed the DANCO cartridge with a MOEN and no longer is there a knock. With both cartridges in my hand and giving them a little shake, both do have something that does rattle around in them. Buy MOEN and not DANCO for a Posi Temp cartridge.
    Last edited: Dec 4, 2009
  5. Runs with bison

    Runs with bison Member

    Messages:
    892
    Location:
    Midwest
    DANCO is crap. They can't even cut the threads properly on a shower arm. I've looked at perhaps a hundred in various stores in the past few months (everybody seems to carry the exact same crap) and NONE of them are cut properly. Wouldn't surprise me at all that they couldn't build a proper shower cartridge if they can't even be bothered to cut threads.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,519
    Location:
    Cave Creek, Arizona
    Moen

    Both valve stems are supposed to "rattle" when you shake them. The problem would be how easily they "rattle" when installed in the valve.
  7. txchad

    txchad New Member

    Messages:
    3
    Location:
    Texas
    The problem with the threads for the shower arms has been identified by Danco and it is being resolved as we speak.
  8. PoorBruce

    PoorBruce New Member

    Messages:
    1
    Location:
    Ann Arbor, MI
    I ran into the same "knock-knock' problem after installing a Danco cartridge in a Moen Posi-Temp faucet. After replacing the Danco cartridge with a Moen cartridge, the problem was resolved. The cartridges are functionally equivalent when "on", but there's a difference when they're "off". Both have some type of a little mobile shuttle that presumably balances the water temperature while "on", i.e. the "pressure balancing spool" that hj mentioned. You can blow air alternately into the hot and cold supply openings and force the shuttle to move, and hear the little knock when it hits its limit. In the "off" position, you can still blow air into the Danco cartridge, if only for an instant, and hear the knock. For the Moen cartridge, the supply openings are completely closed off in the "off" position. I suspect that the water hammer arresting capability in my plumbing isn't perfect, so when the mini shock waves caused by turning off other faucets hit the Danco cartridge when it was in its "off" position, the shuttle danced around a little causing the knocking sound.
  9. WorthFlorida

    WorthFlorida Member

    Messages:
    108
    Location:
    Lake Worth, Florida
    Glad for this site.

    :cool: I'm glad this thread was of help.
  10. Lydia Samad

    Lydia Samad New Member

    Messages:
    1
    Location:
    Texas
    Wanted to say, I found this page by searching for knocking after replacing a posi-temp cartridge. I had the exact same problem. Had to replace a posi-temp cartridge due to there was no hot water coming out. Replaced it with a Danco cartridge and within a month had a dripping problem. Replaced it again with a Danco cartridge and had the knocking noise in the pipe right where the cartridge was. Tried bleeding the pipes, still air in the same spot. Went to Lowes and they were sold out of the Moen cartridges, so tried one more time with a brand new Danco cartridge. Same knocking. Went today and returned it for a Moen cartridge, bingo. No more knocking. Also, I notice the water pressure is much stronger since I put the Moen cartridge in. Thanks to this page, I might have called a plumber. Old thread but good advice. Thank you.

  11. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,519
    Location:
    Cave Creek, Arizona
    quote; Thanks to this page, I might have called a plumber.

    And if you had read some of my other Moen posts, you would have seen that by calling 1-800-BUY-MOEN they would have sent you a cartridge so you wouldn't have had to search for one and buy it.
  12. dhagin

    dhagin builder:anti-builder

    Messages:
    108
    Location:
    oahu
    What's that old sayin... you can lead a horse to water... or something. ;)
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