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where is the best place to put my intake fan?

Discussion in 'Grow Room Design & Setup' started by theceo13, Jun 30, 2010.


    theceo13 Member

    im trying to figure out where to put my intake fan for my grow box. i have the exhaust fan in on of the upper corners of the box, but i didn't know if i should put the intake fan near a bottom corner or in the center of one of the wall....any help would be greatly appreciated

    slump Well-Known Member

    Put it near the bottom...cooler air outside will sit closer to the floor since it's heavier ^^

    growalater Active Member

    Put it close enough on the bottom to move air around but not to far down so it will pass by the plants and not the bottom of the pots.

    darkdestruction420 Well-Known Member

    put it as an exhaust fan and have a passive intake, thats a much better idea than 1 intake and 1 exhaust. Trust me.

    growalater Active Member

    Yea i am running 3 2" passive intake holes. As long as you have a powerful enought exh fan it will pull intake air. and you dont have to worry about smell leaking out with passive too.
    Maui Waui

    Maui Waui Active Member

    so is it better to have passive intake or passive exhaust?

    HookdOnChronics Well-Known Member

    Passive intake on the bottom! YOU WANT an exhaust fan (at the top)

    T.H.Cammo Well-Known Member

    Word! For the best thermo-dynamic air flow, both fans should be "near to" the center of the "Cieling"(right above your light hood), but since you already have one mounted in a corner, the other one should work ok in the opposite corner.

    The reason why 2 exhaust fans work better is simple if you think about it! If you have "X" (blowing in) and "X" (blowing out) - you are only moving "X" amount of air. The only advantage is that each fan is only "working" 1/2 as hard (less strain on the motor, less watts per fan).
    With 2 exhaust fans you are moving 2 x "X" (double the amount) of air. But both fans are working at "normal load".
    It works the same way if you run both fans as "Input Fans", except that that creates an over pressure inside the tent that causes air leaks, into the surrounding room.

    For the most efficient "Passive Intakes", allow 5 times the total area of both fan ports combined, at least 3 times the total area. For example, if you are using two 4" fans - use ten 4" passive intake ports, at least six 4" ports. The larger size for the "passive intake area" allows the air being sucked in to be less restricted (easier airflow). You can position the intake ports around the lower part of the tent so that the incomming air swirls around, in a circle.

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