Exhaust Fan or Intake Fan -- Choose only One Please

Discussion in 'First Time Marijuana Growers' started by motojonas2000, Jan 16, 2010.

  1. Hello there,

    I am putting together a 18 inch wide, by 36 inch long, and 48 inch tall grow cabinet which will be lit with twelve 23 watt cfl's (18,000 total lumens--4,000 lumens/sq-ft--).

    I have also purchased a Computer fan that moves 78 cubic feet of air per minute, and I am debating whether to use it as an intake fan, or an exhaust fan..... (Grow Cabinet is 18 sq-ft)

    Given the box size and lighting i'm using, what is more important to have? An intake, or exhaust fan?

    Also... should I have this fan run constantly, or at intervals of 30 minutes...or something like that?

    What do you guys think?

    Also included a poll:
  2. I would suggest getting another fan and having both...also make sure your cfm on the intake is less than the exhaust
  3. ^Yeah, what Digital Dwarf said. I don't get the poll - as if there were two correct answers. If you only have one fan, it must be an exhaust fan. An intake fan by itself will tend to pressurize your grow space and force smelly air out of places that you don't want it go. You must have negative pressure (partial vacuum by a sucking exhaust fan) in your space.
  4. Absolutely exhaust if only one fan.
  5. An exhaust fan will create suction and an intake of it's own if it is powerful enough and has a fresh air supply.I have a cover on my cabinet w/ an exhaust fan on the right, w/ the left side of the cover open a bit.Lot's of airflow, plants dancing in the wind.
  6. #6 LBH, Jan 16, 2010
    Last edited by a moderator: Jan 16, 2010
  7. I have two computer fans. The exhaust runs continuously and I have a plain jane household thermostat controlling the intake. This keeps airflow moving and controls the temperature.
  8. Thanks for the input everybody, very helpful! The answer is clear, if there is to be only one fan, then an exhaust fan it will be--with a passive intake near the bottom of the cabinet.

    One last thing: Is it best to run the exhaust fan constantly (24hrs/day), or can it come on and off at intervals of 30 minutes?

    Again thanks for all the responses, I appreciate it!!!!
  9. That depends on how committed of a grower you are. You too are living, breathing being. If I lock you in closet,would you like fresh air all the time or every 1/2 hr. ;)
  10. Hi I am new on hear and have a question I am only using one fan (exsaust) is that best my box is only 3' hi 2.5'x2.5'? The room is well vetntelated no moisture in box when lights are off should I shut the fan off too or keep it on

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