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  1. #1
    Join Date
    Apr 2012
    Posts
    2

    Thumbs down Exhaust Fan Venting Question

    I am renovating my 1st floor bathroom and am planning on installing a PANASONIC 110 CFM exhaust fan.

    I can't cut holes in the joists above because there is plumbing in the way and the joists are only 8 inches and my exhaust fan has a 4 inch exhaust.

    I have 3 options:

    1) Lower my ceiling a bit, enough to run the 4 inch duct, but I really don't want to lower my ceiling just for the exhaust fan.

    2) I need to rebuild a soffit where the bathroom wall meets the kitchen behind it, since there is a kitchen exhaust fan above my stove which vents through the shared wall and then out to the exterior. I can run an additional vent for my exhaust fan behind the soffit, but the ductwork would run 2 feet between the joists and then turn 90 degrees downward and then another 90 degrees in the direction of my exterior wall. Is that a problem??

    3) screw the installation of the exhaust fan on my 1st floor bathroom and install it in my 2nd floor bathroom instead.

    I like option 2, but i'm not sure if there's any problems associated with it.

  2. #2
    Join Date
    Dec 2010
    Location
    Houston Texas
    Posts
    2,505

    Default Re: Exhaust Fan Venting Question

    The fan you selected is one of my favorites. Very very quiet.

    I like #2 also if I am thinking the same thing. Panasonic will have a chart or formula all about length of exhaust pipe vs number of elbows vs slope.

  3. #3
    Join Date
    Apr 2012
    Posts
    2

    Default Re: Exhaust Fan Venting Question

    For the life of me I couldn't find anything ******.. but my plan (so far) is...

    Install my Panasonic 110 CFM fan (for my 5x9 bathroom)...


    2 feet of PVC Pipe in between two joists from the fan...

    2 45 degree angles so I can make a right hand turn to bring me into the soffit and just below the joists...

    About a 4 or 5 foot section of PVC sloped downward slightly to allow any potential condensation to drip away...

    It's not a long run.. so in theory, I should be OK.

  4. #4
    Join Date
    May 2011
    Posts
    251

    Default Re: Exhaust Fan Venting Question

    You could also look at a Fantech remote mounted axial fan. You can then just use any HVAC returb boot or just a simple return grill for minium clearance.

    I have a 6" remote fan that draws from two returns in a larger master bath.

    You can alos use 3" up to a 4" axial fan... or better use two return grills and 3" to each to a single fan. Pretty easy to use a 3" or 4" hole saw to cut the holes.

    The remote fans are really, really quiet too. Almost silent if installed with flex duct.
    1925 Two-Story Stucco Beaux Arts Neoclassical

  5. #5
    Join Date
    Jan 2008
    Posts
    1,330

    Default Re: Exhaust Fan Venting Question

    Option #2 sounds good to me. About all I can add is to remember to make all radii as large as possible to maintain the best airflow. I prefer to avoid use of anything non-conventional because future repairs will depend on that particular product or a direct replacement for it being available- which it may not be. Save the more exotic stuff for only things where he conventional things cannot be made to work.

    And definitely vent the bathroom even if the exotic options are needed to do that.

    Phil

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