WC Hammer - can't fix this

Discussion in 'Toilet Forum discussions' started by mystreba, Apr 7, 2013.

  1. mystreba

    mystreba New Member

    Messages:
    16
    Location:
    highland, md
    Break it down...

    I recently installed a WC/Urinal combo in my bath. Fixtures, plumbing and flushometers are all brand new.

    IMG_2622.JPG

    I ran a dedicated 1" supply line directly from my 86-Gal, 40/60 pressure tank to feed these two fixtures. A reducing sleeve in the 1" tee right between the two fixtures sends 3/4" supply over to the urinal. All supply lines are held very securely to the framing with clamps. Supply lines are CPVC all the way to the flushometers.

    WC has a Sloan 136 1.5' top spud flushometer (yes, it's the squat toilet model but the tech at Sloan informed me it was the same as the 110 model except the vacuum breaker tube is longer and just required cutting to size). Urinal has a Kohler K-13519 3/4" top spud flushometer.


    Kohler urinal flushometer works great.

    When I installed and adjusted the Sloan WC flushometer, it worked well for 3-4 flushes. Then the supply line began hammering violently behind the wall. I closed off the stop valve, pulled the piston and re-installed it. Once again, after initial adjustment the flushometer worked well for 3-4 flushes, then the supply line began hammering violently behind the wall. I verified that the piston is correctly sized for the 1.6 GPF Kohler WC. The troubleshooting guide in the installation instructions says "the size of the orifice in the 'bypass' is critical for proper metering of water". Unfortunately they don't bother to indicate what/where said "bypass" is.

    Sometimes the hammering settles into a rhythmic knocking - you can hear the vacuum trying to seal. The knocking won't stop until I also flush the urinal.

    I've adjusted until I'm blue in the face - any thoughts on how to stop the hammering?

    many thanks
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,023
    Location:
    New England
    You may need to install hammer arresters on the lines.
  3. mystreba

    mystreba New Member

    Messages:
    16
    Location:
    highland, md
    Thanks, will do. I can't say it will be an easy job, access-wise. Some questions first:

    1 - Any advice on placement before I get in there and start cutting? See diagram below. Should I put one on each line after the tee or put only one before the tee?
    2 - What type arrestor is recommended for this 1" CPVC installation - air/diaphragm or gas/piston?
    3 - Should it be sized to the pipe or can I install the more common 1/2" arrestor?

    pipes 2.jpg
    Last edited: Apr 8, 2013
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,023
    Location:
    New England
    Functionally, you want the arrestor to be close to the valve so the moving water column has somewhere to go without there being a lot of water left to bang on the valve. But, you may find that the piping is just not anchored well. Still, if it is moving, you want both anchors and the arrestor. I don't have much long-term experience with them...the ones I have are piston type, but they aren't super old. They work. I think you'd find it needs to be sized for the water line and valve you are using otherwise, it may just bottom out and not be able to perform its function...best to see what one of the pros has to say. Some research on the supplier's website and spec sheets may resolve the question.
Similar Threads: Hammer can't
Forum Title Date
Toilet Forum discussions Water hammer...I think?? Aug 21, 2013
Toilet Forum discussions Which fill valve won't have a water hammer? Jun 2, 2013
Toilet Forum discussions Replaced Toto 528 Cap and Now Hammering? Apr 28, 2013
Toilet Forum discussions Toilet flush -*thump*..... doesn't seem to be water hammer Dec 13, 2010
Toilet Forum discussions Water Hammer Aug 13, 2010

Share This Page