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  1. #1
    Join Date
    Jul 2008
    Posts
    14

    Mechanical Noise

    Hello,

    There is a hum coming from the fan in my HVAC unit - it is not the compressor, as I hear the hum when that compressor is on and off. I have 25 feet of flex duct with multiple turns between the HVAC supply and where the flex duct enters a spiral duct that runs the length of my condo. I can hear the hum coming out of the first few ducts especially well - by the time it gets to the later ducts, it's all but dissipated. I don't know how in the world I can still hear that hum 25 feet down the line and after multiple turns, but I can hear it plain as day. I *know* it's coming from the unit itself because when I get up in the closet where the air handler is located, I can hear it coming from the fan.

    Does anybody have any suggestions on how to handle this? Almost as soon as the spiral duct comes out of the wall, there's a 90 degree turn so that the duct then runs parallel to that wall. Does anyone think putting a turning vane or two in that elbow would help deflect this sound? How about insulated flex duct?

    Thanks so much!

  2. #2
    Join Date
    Jan 2008
    Location
    In the work truck
    Posts
    2,998
    i would call a professional service company to look and evaluate your system. this could be something easy to fix or a problem that will cause a catastrophic failure theres only one way to find out.. we can not diagnose the unit by where the sound dissipates in the duct system. and even if we could we are not permitted to. read and understand the site rules. good luck

  3. #3
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Call for an annual clean and check,likely need that anyway,and it's likly something simple,that can be corrected at that time.Tel them what you hear when you schedule the call.

  4. #4
    Join Date
    Jul 2008
    Posts
    14
    It's a brand new unit (about 3 months old). I've had 2 professionals look at it. They both said the humming is normal, and it may very well be. I just don't want to hear it. It was the second professional that installed the 25 ft of duct.

    Any ideas? Do you think the insulated flex duct would help?

  5. #5
    Join Date
    Aug 2003
    Location
    Lincoln, Nebraska
    Posts
    1,051
    It should be under the first year warranty so have them back out to fix it. If it is that loud then it is most likely not normal.

    Its hard to tell from here just what it may be.
    Its a good Life!

  6. #6
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Quote Originally Posted by ms244 View Post
    It's a brand new unit (about 3 months old). I've had 2 professionals look at it. They both said the humming is normal, and it may very well be. I just don't want to hear it. It was the second professional that installed the 25 ft of duct.

    Any ideas? Do you think the insulated flex duct would help?
    Installed the 25 feet of duct ,to do what??


    Turn the circuit breaker off to the indoor unit only,if that's where the hum is coming from.Does it stop??

  7. #7
    Join Date
    Jul 2008
    Posts
    14
    Yes, it stops. It doesn't hum unless the fan is running. It's just the nature of the fan. It's a ClimateMaster geothermal unit. Aside from the company that installed it, I've had a ClimateMaster certified tech and an independent tech look at it. None of them see that there is anything wrong with the unit that would be causing the hum. It's just the way it is.

    My question hasn't been whether the noise is problematic or symptomatic of anything. My question has been how I can prevent the fan sound from getting into the duct and reverberating throughout it. 25 ft of flex duct has not been successful in dampening the sound. The question is solely acoustical in nature.

    Any ideas on sound dampening methods?

  8. #8
    Join Date
    Feb 2007
    Posts
    190
    The flex duct could stop noise transmision. If that did not fix the problem then your noise is coming from the machine. Ductboad or Lined sheet metal can absorb some of this kind of sound

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