Questions about extake fans

Discussion in 'Growing Marijuana Indoors' started by Kaptain Kushtain, Aug 22, 2017.

  1. High all!
    My first girls are in flowering stage and realy starting to smell and since i didn't have a extake fan (only intake) i decided to find a cheap solution.Yesterday i bought a small 8cm by 8cm PC fan and i was so amazed by how well he performed that i bought a second one today.One fan was not enought to push air through my DIY carbon filter so i bought a kitchen stove hood filter (not sure if thats what it's called,but i googled it and the right thing came up lol) with active carbon.
    So my question is- if i put the two fans one behind other will i double the air flow,in my oppinion it's just logic but i have to ask to be sure,or just put them in separate areas of the grow space and just use 2 inline pipes?
    Blaze up!
  2. Pulling air thru the fan is much more efficient than trying to push it thru.

    An exhaust fan will pull in exactly as much air as it exhausts, and that's all most people need.

    The maximum amount of air able to get thru a fan is determined by the maximum, powered rotation rate of its fan blades. If you put those fans in series (one behind the other), I doubt that you'll get twice as much air flow, because both sets of fan blades probably can't rotate twice as fast under power, when in series, and that's what's needed to double the flow rate.

    If possible, change the fan from being an intake fan into being an exhaust fan that sucks air thru the filter before exhausting it. That should greatly increase the air flow.
  3. I have a room fan i modificated for the grow closet and i use him for intake and on the upper side i cut a hole for the air to get out.Because i have really small grow space for now (0,5m2) the heat from my 400w HPS was just massive so i decided to get 2-3 extake fans to move the hot air out.Im gonna put them in the left and right upper corners of the grow closet in separate places for best results.
  4. You don't need an intake fan at all, unless you need to move air in from a remote location. The intake air must be widely separated from the exhaust air, so this could be necessary. Otherwise, you might take in the partly co2 depleted exhaust.

    An intake fan will make it slightly easier for the exhaust fan to exhaust, while increasing the smell escaping.
  5. I red somewhere that extake is better than intake but the size of the fan was a problem and it was quite difficult to modify it for and extake and i didn't have a fan to move the air inside the grow space.Now that i have the 2 extake fans i think i'll remove the big one and just put 1 or 2 inside for air circulation.
    Thanks so much for the info.
  6. Depending on its size, maybe your fan could be modified to exhaust thru a smaller opening than the size of the fan. There are hvac fittings that might be able to attach to the front of the fan with duct tape, and then blow all the fan air thru a smaller opening (but careful about over heating). I've done this with a heater.

    Don't forget, all the air exhausted by an exhaust fan must have been pulled into the grow space by that same fan, so in a sense, an exhaust fan is also an intake fan.

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