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Thread: Rumbling - Ductwork

  1. #1
    DIY Junior Member
    Join Date
    Dec 2010
    Chester County

    Default Rumbling - Ductwork

    I occupy a 2nd flr condo (no one above). I hear rumbling every time I sit down. When I'm up and moving around it seems quiet in my place, but the minute I sit down this rumbling will go on for hours. But, this does not happen every day. It usually happens for days in a row and then stops for a couple days. I had my heating contractor come out twice to check my unit, but at neither time was this
    rumbling happening. The serviceman said that the next time I heard the rumbling to turn my heat
    pump off and see if the rumbling continues. I tried that and when the heater is off, the rumbling
    does continue, so according to my serviceman, it would not be my heat pump.

    I've asked my downstairs neighbor to check with her heating contractor. She said she had heard pulsations but nothing to bother her and I noted to her that I felt a buzz undermy feet as I was talking
    to her. (Note: all units have their own heat pump, my neighbors is in the basement).

    I used to, a couple months ago, get a strong buzz throughout my floor. and my neighbor happened
    to mention that her electrcity had gone off about that time and she had to call her plumbiing
    contractor. Since it's been colder than normal, I'm concerned that this could be dangerous if it
    continues. Does anybody know what could be happening? Thanks.

  2. #2
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona


    Nothing you have told us gives us any hint as to the source of the "sound/feeling". I hope the statement, " her electrcity had gone off about that time and she had to call her plumbiing contractor", does NOT mean she called him about her electric problem. Vibrations, regardless of where they originate, can create resonances which can go a long ways before they manifest themselves, so we cannot tell where they begin, what is causing them, or why YOU feel or hear them in your unit.

  3. #3
    DIY Junior Member
    Join Date
    Dec 2010
    Chester County

    Default Rumbling Ductwork

    The sound is coming from under my feet and into any upholstered furniture. My ductwork is in my
    ceiling. I checked with my neighbors to the left and right of me and they say they have not experienced
    any kind of sounds that I have. But, the neighbors below me had experienced what I had originally
    called "pulsations." It happens whether my neighbors are home or not and it rarely happens after
    11 p.m. or before 5 a.m. My heat pump can be in the off position and these sounds will continue.
    The sounds can be like air moving through a shaft, or a cylinder pumping or like a slight but heavy
    grind. I sometimes feel like "some" "thing" is stronger than it should be. For instance, could the
    neighbor's heat pump be larger than it needs to be for the space it has to heat? Is some wiring
    getting too much juice? I have no idea. I have had heat pumps for over 17 years and have never
    had any problem approaching this. (Note: My downstairs neighbors ducts might be in her floor
    - she has a basement; but the sounds certainly seem like they are coming from right beneath my
    feet and I am on the 2nd floor).

    (P.S. I don't know how to get back to my original post to change it with this info).

  4. #4
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    Ask her where her air grills are. They may be in the ceiling or high on the wall. If so, then her ductwork is probably in her ceiling (your floor). All air handlers and furnaces that I've looked at call for a flexible fabric connection between the air handler itself and the rest of the ductwork to decouple the inherent vibrations of that motorized device from the rigid metal ductwork. This is often left out to save a few bucks. If you take a look at your air handler (the device with the fan and coil in it fed by the heat pump) - check to see if there's a band of fabric between the metal duct connections - it often looks sort of like a short accordian piece. If you can, check your neighbor's unit, too. If you can place your hand on that ductwork at the air handler, you may be able to tell if that's the source of the vibrations and noises. The fans are supposed to be balanced, but if they get any dust or other buildup on them, they can vibrate. If they were cleaned, and the vanes slightly bent, they can vibrate. If the bearing is wearing, they can vibrate. That sound will be transmitted to the ductwork if they did not include the decoupling specified.

    Many air handlers have adjustable fan speeds...hers might be set higher than others, either through preference or necessity to handle the load. Faster speeds will be noisier than slower ones.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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