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  1. #1
    Join Date
    Aug 2016
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    Return air drop to new filter rack

    I currently have a 16x25x1 builder grade filter handler. I'm looking to install a lennox 5" filter. Currently there is a 90 degree soft radius (outside edge only) going into the filter. The return drop is 10x25 and it's a 3.5 ton system. I have contacted a few HVAC installers for the new filter rack. Most of them recommended just bringing the 10x25 all the way down, cap the end off, and put the air rack between that and the furnace. I'm no expert, but is that OK for air flow? I just figured they soft 90 radius was there for a reason. Though the more I looked it seems like unless it's a soft radius on interior AND exterior it doesn't do much. Will the plan work fine? Last thing I want to do is make my return noticeably less efficient. Thanks!

  2. #2
    Join Date
    Aug 2016
    Posts
    16
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    Thread Starter
    Also, how does the Lennox HC compare to the same size aprilaire system? Should I hold out for an aprilaire or they more or less the same difference? I have an aprilaire on my old house and liked it, never ventured into lennox.

  3. #3
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    9,978
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    Quote Originally Posted by needshvac View Post

    I currently have a 16x25x1 builder grade filter handler. I'm looking to install a lennox 5" filter.

    Currently there is a 90 degree soft radius (outside edge only) going into the filter.
    The return drop is 10x25 and it's a 3.5 ton system.

    I have contacted a few HVAC installers for the new filter rack. Most of them recommended just bringing the 10x25 all the way down, cap the end off, and put the air rack between that and the furnace. I'm no expert, but is that OK for air flow?

    I just figured the soft 90 radius was there for a reason.

    Though the more I looked it seems like unless it's a soft radius on interior AND exterior it doesn't do much.
    Will the plan work fine?

    Last thing I want to do is make my return noticeably less efficient. Thanks!
    Last thing U want to do
    Listen to someone who does not wish to present the
    overall system operating perspective.

    Filter location may be necessary to be in the vertical drop.
    __ Fit-up issues to be addressed

    LOCATION: _ _ _ _ _ zip

    FACTS to investigate
    1
    E.S.P. Analysis of current operation
    _____-- Supply, Return, Filter & Total dP

    2
    Comprehensive ACCA Manual D calculation

    3
    Required system flow rate may be 360 to 450 CFM / Ton
    depending on Location _________ Humid ___ Dry Region

    4
    Mfg. / Model number of air handler / furnace ___________

    My Gmail address: racingdan11
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

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