Humidifier water hammer

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by george1951, Mar 2, 2014.

  1. george1951

    george1951 New Member

    Mar 2, 2014
    I hear a loud water hammer noise when the water flow to my Bryant humidifier #HUMMBBLBP2417 shuts on or off (I can't tell which). I'm pretty sure it's the humidifier because I don't hear the noise when I turn it off. I hear the noise on the first floor of my house coming from the basement but when I go down to the basement to find the source, I can't. I have an expansion tank on the cold water line near the hot water heater. My furnace company replaced the humidifier solenoid valve and I installed a Sioux Chief mini water hammer arrester on the humidifier's supply line but neither of these have worked. Does anybody have any ideas on how to fix my problem? Thanks.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    Watch the water line to the humidifier, and have someone (if you can't do it) turn the humidifier control up and down to cause it to turn on and off. See if you can see the line moving. The hammer arrester needs to be as close to the valve as conveniently possible for it to work best. Maybe just some clamps may solve it, or moving the arrestor.
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  4. DonL

    DonL Jack of all trades Master of one

    Mar 30, 2011
    Rocket Scientist
    Houston, TX
    You may be better off to just restrict the water flow to the humidifier.

    The slower the flow the less power the water hammer has.

    Good Luck on your project.
  5. jim mills

    jim mills New Member

    Jan 9, 2014
    I'm with Donl on this one. I don't have a lot of faith in those mini arrestors. Just turn the water down.
  6. Dana

    Dana In the trades

    Jan 14, 2009
    The best solution is to turn off the humidifier altogether, and air-seal the house to the point where low wintertime humidity issues aren't a problem. Dry indoor air in wintertime is a symptom of excessive ventilation/air infiltration. Humidifiers are the band-aid, but it's a remedy that can do more harm than good in the long term.

    Humidifiers operated without sufficient care can end up decreasing the indoor air quality by storing enough wintertime moisture up inside your walls to promote high mold-spore counts in the springtime as the average temperature of your wall assemblies increase, releasing that moisture just as it gets to be warm enough for molds to reproduce rapidly.

    It's nearly impossible to retro-fit air seal to the point that the house is TOO tight, and most breathing/bathing/cooking humans will provide more than enough moisture to the air to keep it at 30-35% relative humidity @ 70F indoors even during cold snaps, as long as you have at least 2 occupants. Only if you smoke or use a lot of toxic aerosols indoors would you need to ventilate to the point where the indoor humidity levels would be below 30% and begin to feel dry. At 40% RH and above in mid-winter the average temp at exterior sheathing of framed walls in a central PA climate stays below the indoor air's dew point for most of the winter, and loads up. If you're running the humidifier, keeping it at 30-35% will be the best compromise for comfort and human/house health.
  7. StacyGomez

    StacyGomez New Member

    May 25, 2015
    Last edited: May 30, 2015
  8. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    Change the supply line from copper to plastic so it can "expand' to absorb the water hammer.
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