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  1. #21
    Join Date
    May 2013
    Posts
    2

    Default Re: Dripping sound in ducts

    Old thread, but I want to spread the word about my solution to this problem.

    I had a sound in my hvac duct that I swore was water dripping. It sounded exactly like water. But it wasn't a drip at all. Instead it was, as many others suggested, thermal expansion. But it was a specific form of thermal expansion. Specifically, my water drip sound (I swore it was water!) came from the point where an elbow HVAC joint joined with my long, straight HVAC duct. I put a large worm gear clamp around the point where the long, straight duct hit the point where it joined the other duct and tightened it down hard. That worked like a charm, the sound immediately went away. You can test it before you use (or buy) the worm gear clamp by grabbing the duct with your hands and squeezing while it's making the sound. If it stops, buy the band and tighten it right where the two ducts join. Mine hasn't come back after a month or two of putting the clamp on. Just google "worm gear clamp" and you'll see what I mean. Just get a big enough one for your duct. Good luck!

  2. #22
    Join Date
    Aug 2013
    Posts
    3

    Default Re: Dripping sound in ducts

    I came across this thread and wanted to post, as I am having a somewhat similar issue.

    In the last week, I have noticed a dripping/clicking sound coming a specific, narrow wall near the front of the house. Basically, when you walk in the house it is the wall that separates the hallway from the kitchen. It is a ceiling-to-floor wall, height-wise, and is maybe half a foot wide with a depth of two feet or so.

    Anyway, I hear a loud series of clicks or drips in the wall maybe 30 seconds or so after the central air conditioning comes on. There will be between 10 and 20 clicks like this at 5 to 10 second intervals, at which point they get less frequent until the ac shuts off.

    After the ac has been off for a minute or so, I will again hear several clicks in this wall at short intervals, which then taper off to being less and less frequent until the ac clicks on.

    At first I thought this was dripping, but when I press my ear right up against the wall it sounds more like an aluminum clicking or popping sound. And again it is confined to this one wall, which is at the front of the house while the ac unit is in the back yard.

    Any thoughts as what could be happening?

  3. #23
    Join Date
    Aug 2007
    Posts
    7,154

    Default Re: Dripping sound in ducts

    Quote Originally Posted by Adam81 View Post
    Anyway, I hear a loud series of clicks or drips in the wall maybe 30 seconds or so after the central air conditioning comes on. There will be between 10 and 20 clicks like this at 5 to 10 second intervals, at which point they get less frequent until the ac shuts off.

    After the ac has been off for a minute or so, I will again hear several clicks in this wall at short intervals, which then taper off to being less and less frequent until the ac clicks on.
    Normal thermal expansion and contraction of the duct within the wall. Metal at ambient temperature makes no noise, heat or cool that metal and it will either expand or contract, this movement is what is causing the clicking/dripping sound. Also, the sound can be more pronounced where it is touching framing or the back of drywall, etc. You've got one surface moving against a stationary object, you're going to get friction and noise.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  4. #24
    Join Date
    Aug 2013
    Posts
    3

    Default Re: Dripping sound in ducts

    Quote Originally Posted by A. Spruce View Post
    Normal thermal expansion and contraction of the duct within the wall. Metal at ambient temperature makes no noise, heat or cool that metal and it will either expand or contract, this movement is what is causing the clicking/dripping sound. Also, the sound can be more pronounced where it is touching framing or the back of drywall, etc. You've got one surface moving against a stationary object, you're going to get friction and noise.
    Thanks so much for the quick reply! That definitely puts my mind at ease, particularly that it is normal expansion/contraction rather than a water drip. Thanks again.

  5. #25
    Join Date
    Aug 2013
    Posts
    3

    Default Re: Dripping sound in ducts

    Quote Originally Posted by Adam81 View Post
    Thanks so much for the quick reply! That definitely puts my mind at ease, particularly that it is normal expansion/contraction rather than a water drip. Thanks again.
    I just wanted to follow up here with further confirmation of the expansion/contraction issue as the culprit of my issue. Last night we turned the AC off completely and I did not hear those sounds at all for the duration of the evening and overnight hours. Thanks again!

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