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Ventalation Question

Discussion in 'Growing Marijuana Indoors' started by Bigdad, Sep 30, 2011.

  1. #1 Bigdad, Sep 30, 2011
    I have a 25 cubic foot grow cabinet, I have a 122 cfm axial fan exhausting from the back (up high) I am having trouble with temps. I have 4 - 2" passive intakes on the bottom, I suspect that is not enough, is there a formula as to how much intake area to have:confused:
     
  2. #2 kdspecial, Sep 30, 2011
    I always thought you want the same intake size as outtake size to keep the pressure right. But I'm not 100% sure on that. there is a sticky Thread on ventilation in the Grow Space setup/design forums.

    Do you have any fans circulating air inside the space? that will help cool it some.

    kd
     
  3. #3 Bigdad, Sep 30, 2011
    I know that I have negative pressure now (lighter at the intake) I think I have have to much air going out and not enough coming in.
     
  4. #4 toastybiz, Sep 30, 2011
    You can't have too much going out and not enough going in, that would result in a vacuum inside your grow space. The amount coming in equals the amount going out, pretty much by definition. But it's possible that your exhaust is pulling harder than your intakes can provide, in which case the size of your intakes is restricting how much can go in and your exhaust is not working at full capacity. But some negative pressure is good for keeping odor from escaping.

    There isn't a magic formula because there are other very important variables besides the size and volume of your intake and exhaust. Also depends on the temp of your intake and the temps being generated inside the box.

    Where is your grow op? Specifically what kind of intake air is it getting? Is it cool?

    The best solution may be to get an air-cooled hood...
     
  5. #5 Bigdad, Oct 1, 2011
    It's relatively cool air coming in 76 - 78, I don't have to worry about odor, more of the semi stealth thing, with the light. I can hear and feel the difference on the exhaust when the door is open, I think I will add more intake. My thinking originally was that with a 120 cfm it would replace the air before it could get heated up. Was really hoping I could put a 250 hps in there. Right now I can't run 330 cfl. I have not seen any cool tube type for 250 hps, would have to use 400 and that would be a ton of light in this space, or so I'm told.
     

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