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  1. #1
    Join Date
    Aug 2008
    Location
    Ontario,Canada
    Posts
    20

    Low frequency "whomp","whomp" sound from furnace motor.

    Hi: We just had a new HE two-stage, variable speed, d.c. motor furnace and new single-stage A/C with a two-stage thermostat. I get a constant "whomp","whomp" low frequency sound, maybe twice a second, while furnace is running. It won't do it on "constant on fan" due to a much lower speed, so it must be a speed thing! You can't really hear this noise when you are right at the furnace, but if you go to the other end of the house, away from the furnace you can hear it. I had an old fridge that made that 60hz hum,this is similar , but pitch goes up and down. I thought these here d.c. motors are supposed to be super quiet? Very annoying when everything is quiet...sound like a train idling not far away! Anyone else have this annoyance and is it fixable? p.s. Sorry for the extra title! Thanks, Huck

  2. #2
    Join Date
    Jan 2002
    Location
    Ft.Worth,Tx
    Posts
    4,584
    Ramp up sometimes makes that sound , but after motor is moving it stops no more than a couple of seconds. Might want to have it checked out,blower wheel might be out of balance.
    "Everyday above ground, is a good day".
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  3. #3
    Join Date
    Sep 2005
    Location
    Atlanta GA area
    Posts
    21,184
    Three things:

    1) On some furnaces there is a bracket that holds the blower safe from damage during shipping... it may still be in there (supposed to be removed with installation).

    2) The furnace needs to be 'set up' when it is first run. The installing tech may or may not have done this (adjust air flow).

    3) There is always the possibility that you may need some modification of the ductwork to adequately and properly move the air around your home.

    All 3 of these things should be addressed by your installing contractor.
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  4. #4
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,744
    install instructions sucked into blower??

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,119
    Does it do it in cooling, first stage heat, and second stage heat. Or just one or 2 of those modes.
    And which modes if not all of them.

    Grossly undersized ducts, will cause VS blowers to rev up high trying to move the proper amount of air. And can cause noise issues.
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  6. #6
    Join Date
    Aug 2008
    Location
    Ontario,Canada
    Posts
    20
    Quote Originally Posted by t527ed View Post
    install instructions sucked into blower??
    Thanks! That sounds more like it! They never stuck around long enough to run it through a complete cycle!! When I started it up the following day, the burner kept cutting out when the stat was calling for heat! I phoned the company and they sent someone out three days after my call and the tech found two thermostat wires were crossed(W-1 and W-2...first and second stage).... they left saying that was the problem, so that goes to show that they never put it through the paces, or they would have found the crossed wires!. They had to come out twice the same day..., burner still cutting out on the high limit(overheat) days after the original install! WTF! Thanks, Huck

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,119
    If thats the way they set them up.
    You might want to get an extended labor and parts warranty.
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  8. #8
    Join Date
    Aug 2008
    Location
    Ontario,Canada
    Posts
    20
    Quote Originally Posted by beenthere View Post
    Does it do it in cooling, first stage heat, and second stage heat. Or just one or 2 of those modes.
    And which modes if not all of them.

    Grossly undersized ducts, will cause VS blowers to rev up high trying to move the proper amount of air. And can cause noise issues.
    Hi: To be honest...I never really noticed the noise with the A/C running,only had the air running a couple times, but pretty sure it does it only on the first stage heat. It's too warm for the furnace, but not warm enough for the A/C., but I will check tomorrow when the furnace starts in second stage. Usually the house is at least four degrees lower than the set-point, so second stage comes on automatically. Thanks, Huck

  9. #9
    Join Date
    Mar 2005
    Location
    Suppy NC
    Posts
    4,513
    unit is under warranty so you should call and have it looked at and fixed/

    if you are not happy with the contractor you had install the unit then call the manufacturer and see if they will help you get a different contractor under the warranty period.

    may have to pay labor but if problems are solved it may be worth it

  10. #10
    Join Date
    Aug 2008
    Location
    Ontario,Canada
    Posts
    20
    Thanks to all who tried helping me out on this, but today the furnace was off and I still heard the sound....tracked it down to my two year old Amana fridge!! Any way to fix it, or just fugedaboudit? Thanks, Huck

  11. #11
    Join Date
    Aug 2007
    Location
    MN
    Posts
    2,677
    Quote Originally Posted by Huck50 View Post
    Thanks to all who tried helping me out on this, but today the furnace was off and I still heard the sound....tracked it down to my two year old Amana fridge!! Any way to fix it, or just fugedaboudit? Thanks, Huck
    figures It could be simple, check under neath for dirt/paper/mice in the condenser fan area. Or if it is more than that, call in the appliance guy.
    You can't fix stupid

  12. #12
    Join Date
    Dec 2007
    Location
    Cedar Grove, Wi-Sheboygan
    Posts
    1,582
    Check the top of the frig there might be something sitting on top that is causing the noise, I know every once in awhile I put something up on top that cause's rattling nosie from something laying up there

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