So i've done my research for a while now and i decided in about 3 months im going to start my grow, but im still VERY confused about how to set up an exhaust. I'm gonna be growing in a closet about 3x5. So if someone would be so kind as to explain to me...step by step lol what i'll need and how to set up a simple, working (of course) exhaust. PLEASEEEE!

you really only need an exhuast if you are goin to be using hps lights, i have 6 4 foot flouros and 2 23 watt cfls in a box smaller than what you got and all i have is an oscilating fan blowin on em and it never gets much above 85

There isn't any information here which would allow us to explain anything about anything about your set up. Like the kind sir above me pointed out you only need to vent with an HID really in enclosed spaces.

Anyways generally people feel it is more efficient to suck the air over the light through a fan and out the room (where is up to you, you might have to partially destroy your house to do this)
Hence

<<<Air<<< (Exit))))[space between grow and place to vent])))))))squirel fan))))))))))))))))))))))Light)))))))))))))Optiona l Filter <<<Air

lol

You want to get all the hot air at the top of your closet through an exhaust using and inline fan. Take in fresh air from the bottom also using a inline fan. Get some flex tubing.

do you have a place to event to is it going outside? is this closet in the basement or the top floor? is it going to be air tight? I have my room in the basement where it stays very cool even in the summer, since my room isn't air tight I use a 4 inch cpu fan with a DIY carbon on it. I placed it as high in the room as I could. it removes some of the hotter air and it brings in fresh air as it removes the air. if your closet is air tight you will need to bring in fresh air some how. what I recomend is the before you go through the venting that you set up your closet with no mplants and see how hot it gets you might not even need to to vent you might just need a Cardin filter for order controls

I live in an apartment so destroying anything would be out of the question. i did plan on using cfl's and no the closet isnt air tight. would air flow through the cracks in the door be enough? should i open the door every once in a while?

I grew with over 300 watts of cfl in a smallish closet in a desert in a hot home up stairs and with the door open I could keep my temps to 90 or less. I am a firm believer that you should put as many cfls in the area as possible and if a heat issue occurs remove as many cfls as necessary to keep it managable.

You can keep your door open to cool it with the lights on and plan for the lights to be on at the coldest times of the day

if your gonna use cfls all you need is a small fan you'll be good

Hi, OK here goes... I grow in a double door closet. 2x10 x8 (160cuft of air) I use 1/3 for the veg side and 2/3 for the flowering side. I use a 400watt HPS light with a cooling hood for flowering, and t-5's for veg side.
You want to be able to change the total air volume of the space in less than 5 minutes. Your volume I'm guessing is 3 x 5 x 8?, which equals 120 cubic feet of air. So a small exhuast fan that would remove a 120 cubic feet of air in 5 minutes would be around 25 - 30 cfm. I recomend going much bigger though, like maybe 2 and a half times, so maybe a 75cfm fan or bigger. Reason being is you can use a variable speed controller to adjust down the speed of the larger fan to cut down on noise. Otherwise the smaller fan has to run balls out all the time to cool or dehumidify and you have no way of controlling noise. A bigger fan is nice too for when summer comes and the room gets even hotter, as well as for the beefier construction that doesn't work as hard or wear out as quickly. The size of the fan & ducting relates to the size ducting you want to have on your air cooled HPS light hood. Usually 4 to 6 inch ducting for a closet.
You need to get an 'atmospheric controller' of some kind to run your exhuast fan automatically within a certain temp or humidity range. You'll also want to use a charcoal filter in the line somewhere. The filter can go on at the front or rear, just make sure it can handle whatever cfm fan you get.
So for my closet I use a 465cfm 6" Vortex in line fan mounted in my attic with a Can 50 carbon filter (38 special) it vents out through, (I went real big because I eventually want to vent a second smaller closet through it.) At this point though I can change out the air almost 3 times in a minute if I want, I actually run it at around 1/2 speed most of the time meaning 230 cfm are being removed a minute, still bigger than I'll ever need until the 2nd closet is on line.
The ducting goes down through my closet ceiling into the flowering side and to the hood of the 400watt cool breeze light I use. The fan is plugged into a variable speed controller, which in turn is plugged into my atmospheric controller. Additionally I have a small 2 quart dehumidifier in the space which is also plugged into the atmospheric controller. So the fan runs whenever the temp climbs over 75 degrees (most of the time) and the de-humidifier runs whenever the humidity is over 50%.
The doors on the closet aren't air tight so I don't use an intake vent but if I did I'd add an intake in the floor from the basement crawl space where the air is cool. Hope this makes a little sense and helps. I attached a few pics that hopefully will help explain a bit more.
Similarly, I also recomend using a Coleman cooler in a size that works in your space for a reservoir. Light proof, keeps things cool and dampens the sound of my pumps working, sturdy too! Large reservoirs don't go through drastic changes in short periods of time pH and TDS wise. You can go on vacation!
Lastly, I'd get Jorge Cervantes marijuana Horticulture bible. Lots for you in there. I'll subscribe to this thread if you've got questions. Otherwise Happy Gardening! GrowIT!

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Great info. mucho appreciated. anymore questions i know where to go. THANKS