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  1. #1
    Join Date
    Nov 2011
    Posts
    9

    Air Return sounds like a jet plane taking off

    Just had a new furnace installed...I think it is sized appropriately for the 2,000 suare feet house. Single stage, 70,000 BTU, - Carrier Comfort 80. I had a Carrier BTU 100,000 that this replaced.

    The furnace is quiet, but the air whooshing through the air return sounds like a jet plane. The openning is 12 x 30. The installer bent the slats of the air return grille so they would be more open...but not much different.

    Any ideas?

  2. #2
    Join Date
    Nov 2011
    Posts
    9
    this return is the only one and goes directly into the space under the furnace. the opening into the furnace is 25X14

  3. #3
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,012
    Well, I'm guessing it requires 950 to 1050-CFM of airflow to keep the temp-rise within 60-F specs with 56,000-BTUH Output.

    Where is the RA filter located?

    To get it as quiet as possible I'd want 400-fpm velocity or less through the RA grille.

    Hart & Cooley says a 24X24 grille will flow 1083-cfm at 400-fpm velocity.
    Or, use a 30X18 grille that will flow 1016-CFM at 400-fpm velocity.

    If U want a quieter RA grille, a 30X12 will normally only flow 674-CFM at 400-fpm velocity, it is too small... Hart & Cooley RA grille numbers.

  4. #4
    Join Date
    Nov 2011
    Posts
    9
    The filter is at the bottom of the furnace, not at this RA grille. The 12x30 openning where the RA is located is framed in wood. My old furnace did not make this noise and this new furnace is smaller. (30,000 less btu). Same manufacturer - Carrier.

    When I take the RA grill off, no noise. The air being sucked through the openning is much stronger than my last furnace.

    So are you telling me that this openning that is framed with 2x4s with two additional vertical studs is too small? What do you suggest?

  5. #5
    Join Date
    Jul 2009
    Location
    King Ranch Texas
    Posts
    216
    if your set up allows, add another return into the same return air plenum that feeds your air handler filter area.
    Sic semper tyrannis

    ‚——’――‘;====±—- * * * * * *
    !‚–’――ƒΉΆ

  6. #6
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,787
    deejoe,


    This is the Ask Our Pro's forum. In order to post advice here, you must have verified qualifications and have been approved by the AOP Committee.

    You can find the rules for posting and qualifications here.

  7. #7
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,744
    could have the blower set to high

  8. #8
    Join Date
    Mar 2008
    Location
    Baltimore MD and Ridgebury PA
    Posts
    542
    I would wonder if the fan speed of the new furnace is set higher than that of the old furnace. In addition to adding a return, you could always have the RA grille replaced with a better one that allows more airflow. I'm assuming you have a cheap stamped face grille. They make commercial grade ones that are better designed to allow more airflow.

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