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  1. #1
    Join Date
    Feb 2008
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    21

    Default Noisey floor vent

    I had a furnace installed that is a bit to large for the house. I did not realize this until after the fact and the installer did not tell me this ahead before installing it. It appears to work fine but the air flow in the existing vents makes noise. I am trying to sell my home and do not want to go the expense of another install so is there something that I can wrap them in to help muffle the sound. It is not terrible so I think that would be the answer. Also, will the furnace size be an issue for home inspector? Good grief, will it ever end?

  2. #2
    Join Date
    Jul 2009
    Location
    Northeast
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    661

    Default Re: Noisey floor vent

    Furnaces blower motors are sized in tonnage or the amount of air that it will move, if your furnace is oversized you may be pushing to much air which will cause a sort of whistling noise. I doubt that changing the blower motor to one that pushes less air would be wise as you would have problems with the high limit or furnace overheating and shutting down. If you are hearing a banging noise it is more than likely that the Duct work or Plenums lack crossbracing (the plenum or duct is bent diagonally making it more rigid) so when the furnace turns on it won't push out the sides of the Supply Plenum or suck in the Sides on the Return Plenum making a popping noise. Short of replacing the plenums a 1 x 1/4 x L piece of steel could be screwed diagonally to the plenum to make it more rigid. If the Contractor sized the Furnace to fit your house and it's oversized and you knew nothing of it he may be liable for a replacement. Good Luck!!!
    Last edited by Sten; 09-22-2009 at 06:45 AM.

  3. #3
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Noisey floor vent

    It's not uncommon to have velocity noise when new efficient furnaces are installed ..... usually the HVAC company is economizing the install for a variety of reasons.

    As already mentioned there can also be noise from the ducting and trunks expanding and contracting with higher velocity air moving through them.

    However, depending on the furnace there may be a multi-speed or variable speed blower motor installed which allows a slower speed without really any issues with tripping the high limit. Lowering the blower motor speed will reduce the velocity noise .... but ..... this also impacts the balancing of the system's air flow.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  4. #4
    Join Date
    Jul 2009
    Location
    Northeast
    Posts
    661

    Default Re: Noisey floor vent

    If you are getting velocity noise through supplies your Furnace is pushing to much air (not sized right) or your supplies are undersized (not sized right). I have only found a couple of systems like this and it wasn't because of a high efficiency unit, Bottom line, if it is sized correctly you should hear next to nothing. If the ductwork has crossbracing you should not get popping noises or, expansion and contracting. If you lower the blower motor speed you will not get the required CFMs. Economizing a system usually ends up with a complaint and is done to save the Contractor $$$. "Do It Right Do It Once" Good Luck!!!
    Last edited by Sten; 09-23-2009 at 08:30 AM.

  5. #5
    Join Date
    Feb 2010
    Location
    Iowa, Quad-Cities area
    Posts
    129

    Default Re: Noisey floor vent

    Quote Originally Posted by dlh3354 View Post
    I had a furnace installed that is a bit to large for the house. I did not realize this until after the fact and the installer did not tell me this ahead before installing it. It appears to work fine but the air flow in the existing vents makes noise. I am trying to sell my home and do not want to go the expense of another install so is there something that I can wrap them in to help muffle the sound. It is not terrible so I think that would be the answer. Also, will the furnace size be an issue for home inspector? Good grief, will it ever end?
    You don't say where the furnace is located but if it's in the basement you could relieve some of the air noise (pressure) there. The newer furnaces have pretty strong blowers, especially oversized (larger) furnaces.

  6. #6
    Join Date
    Jul 2009
    Location
    Northeast
    Posts
    661

    Default Re: Noisey floor vent

    Good thinking, he could always put a run into the cellar, and also a return.

  7. #7
    Join Date
    Jan 2010
    Posts
    163

    Default Re: Noisey floor vent

    Slowing the fan down as Canuk suggested is the first and easiest thing to try. The installer would likely do this, no charge, since he admitted to over-sizing the furnace.

    If the noise seems to be caused as the air rushes thru the vents of the registers, you might also try installing new registers that are rated for higher velocity and less noise. Manufacturers of registers supply specifications on every register they make to show how they perform at given velocities and CFM's. They are also rated for noise levels.

  8. #8
    Join Date
    Feb 2010
    Location
    Iowa, Quad-Cities area
    Posts
    129

    Default Re: Noisey floor vent

    Quote Originally Posted by Sten View Post
    Good thinking, he could always put a run into the cellar, and also a return.
    Even a blind hog finds a nut sometimes. LOL

  9. #9
    Join Date
    Jul 2009
    Location
    Northeast
    Posts
    661

    Default Re: Noisey floor vent

    Quote Originally Posted by Bob Gabrilson View Post
    Even a blind hog finds a nut sometimes. LOL
    Bob,
    On your TOH control panel there is a link that will let you receive private messages, you should activate it.

  10. #10
    Join Date
    Feb 2010
    Location
    Iowa, Quad-Cities area
    Posts
    129

    Default Re: Noisey floor vent

    Quote Originally Posted by Sten View Post
    Bob,
    On your TOH control panel there is a link that will let you receive private messages, you should activate it.
    Thank you. I'll look for that. I appreciate the advise.

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