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Thread: Fan Noise

  1. #1
    Join Date
    Dec 2005
    Posts
    3

    Hmm

    A local installer has installed a Lennox HSX15048 4 ton AC, a C3350/60C Coil, and a Lennox G61MP60C110 Furnace. I requested a G61MPV60C110 furnace with a variable speed fan. The installer says that a variable speed fan furnace will be noisy due to the cavitation of the fan. I have a 20 by 20 inch drop to the furnace filter for plenty of return air. Is it true that a variable speed fan will be noisy due to cavitation?

  2. #2
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    No.
    They can in some cases move more air then a standard motor,this would be the required amount of air,sometimes due to small ducts a standard motor can't move the required amount.
    If this were the case,they can make more "air noise".

  3. #3
    Join Date
    Dec 2005
    Posts
    3
    I am also increasing the return air vent sizes and the drop from an 12 inch by 18 inch drop to a 20 by 20 drop.

    I am being told by the HVAC installer that increasing the size of the drop from a 12 inch by 18 inch drop to a 20 by 20 drop will void the system warranty because the 20 by 20 will move less air through the system. Is this true?

  4. #4
    Join Date
    Feb 2004
    Posts
    2,597
    are you going to have him do anything w/ the supply ducting?

    what size now?

    how many and what size branch ducts?

    why a 4 ton?


    [Edited by billva on 12-02-2005 at 05:14 PM]

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    66,818
    Where did you find this guy.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  6. #6
    Join Date
    Jan 2004
    Posts
    157
    noise reduction on return I size 177 square inches per ton on a 4 ton return common size for filter would be 25x30, and I like atleast a 2 ft insulated box on the return at the grille and the furnace to help with the noise reduction,always done this and dont have any problems with noise out of vsp or any other furnaces.

  7. #7
    Join Date
    Dec 2005
    Posts
    3
    I am increasing the size of the return air by 50 percent to make sure I have enough air flow. The company is a reputable local company with impeccable credentials from the better business bureau.


  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    66,818
    Originally posted by brenttew
    I am increasing the size of the return air by 50 percent to make sure I have enough air flow. The company is a reputable local company with impeccable credentials from the better business bureau.

    Ask him how many VS systems they have installed.

    Going from a 12 x 18 to a 20 x 20 will slow down the velocity, not the volume.

    Ask him to explain how it wil decrease the volume.

    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  9. #9
    Join Date
    Nov 2000
    Location
    Waco, Texas, USA
    Posts
    6,153
    It is not possible to have any sort of "credentials" from the BBB. The only thing you can find out from the BBB is if they have a satisfactory or unsatisfactory record and how many complaints they have had in the past 3 yrs.

    Some of the WORST hvac companies are members of the BBB. In fact if they are members I would be leary of them.
    "And remember my sentimental friend......that a heart is not judged by how much you love, but by how much you are loved by others" - Wizard of Oz.

  10. #10
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    Originally posted by brenttew
    I am also increasing the return air vent sizes and the drop from an 12 inch by 18 inch drop to a 20 by 20 drop.

    I am being told by the HVAC installer that increasing the size of the drop from a 12 inch by 18 inch drop to a 20 by 20 drop will void the system warranty because the 20 by 20 will move less air through the system. Is this true?

    You need to talk to the installer's boss....he's either full of it or ignorant and doesn't want to increase the size.Your way will be quieter also...
    If everything was always done "by the book"....the book would never change.

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