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Question re: wind-driven ventilator

open_a_window | Posted in General Questions on

Hi – first time poster with an atypical situation. I am trying to generate interior airflow in a commercial building that currently has no ventilation (no windows, no exhaust). It is not possible to penetrate the roof so I am thinking of ducting a rooftop ventilator to the first floor as an assisted return. The intake is the open transom above the front door ( I might add fans here if need be). The hope is that air will travel through the first floor hallway, up the stairwell, through the second floor mezzanine and back through the first floor return (the proposed ducted wind-driven ventilator) I realize this is confusing, it’s a strange layout. My questions are, (1) is this a totally hair-brained idea? (2) I am considering using a 12″ base diameter ventilator rated at 400cfm @ 4mph wind, what size duct to use? I am thinking about 6×14 rectangular at this point. Please see attached mockup image Thanks very much in advance. Nick

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  1. Expert Member


    That's a fun project in a Heath-Robinson kind of way.

    I think the problem is the inconsistent rate of ventilation. If you are trying to induce so many air-changes in the building, you don't want that rate to vary based solely on how much wind happens to be occurring. Wouldn't a small powered fan in the transom work?

  2. Expert Member
    BILL WICHERS | | #2

    +1 for using a fan instead of a wind driven turbine here. A slow, but steady, airflow is better than a random controlled-by-nature airflow that comes in bursts. Aside from that, I don't really see a problem here with your proposed system. I thiink you'll find round duct is easier to adapt and work with for this type of application though, and it's much less likely to make annoying sounds when the wind blows.

    Don't underestimate how much everyone in that building will come to hate annoying ductwork sounds. Random bongs and booms that sound like metallic thunder are incredibly annoying and will drive the occupants crazy. Round duct is much less prone to making annoying noises.


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