# Often overlooked by newbs setting up - exhaust fans



## guru_gil (Apr 11, 2007)

I have seen lots of rooms being built or in various stages of their ever-evolving forms.  One of the most commonly overlooked or last added, from my experience, is also one of the most important and easiest to plan for at the start - it also needs to be, and the two most common things I hear when I mention its either total absence or (very common) some half-assed weak, obviously low on the list existence, like a bathroom vent fan in a corner or just circulation fans - which are essential but not at all the same as an *EXHAUST FAN*!

Yes, the common exhaust fan is a misunderstood, oft ignored creature, rarely found in sufficient size and health despite its critical role in the overall grow room environment.

I prefer lights that can be attached to flex tubing used as exhaust tubing.  An "O" clamp around the exhaust port on the light, and you run the 4" or 6" or up to 12" exhaust ducting either directly to the inline fan, or to a reducer (so ducting from two or three lights are input into a T or a 3 end fixture and it reduces to a single out port, which is then run to the inline fan, and from there the ducting is run to an exhaust port in the wall / ceiling and outside.  If smell is an issue you can add an inline carbon filter and they work great, the odor is gone in a properly fitted and sized carbon linline filter.

I reccomend a drier exhaust port on the outside of the house, paint it the same color as the house exterior and have the type with a small grill and lots of little slats which close when the fan is not on - so insects cannot work their way up the ducting and into your room.

Final and IMPORTANT note which is also overlooked far too often.
OVERSIZE your FAN.  I first bought a 8" fan for a 15x15' room with three lights, two 600w and one 400w and thought that was sufficient.  Well, it was pressed into duty and did work, but I had to run it at full speed all the time to keep the room air at sufficient output flow.  Later I upsized to a 12" Vortex fan, and kept the 6" ducting but had a duct fitting with 6" on one end and an expansion to a 12" output.  This fan was far more powerful and thus I could run it at half its total speed, reducing the noise by a great deal.  The 8" fan on full speed sounded like an industrial fan running in the back room, people using the adjacent bathroom commented a few times, asking what was running in the next room that was so loud.  Now with a 12" you can not hear it at all, it moves more out more easily, I can upsize the lights or add to them if need be, and my plants have a constant flow of fresh air - from an input side with a series of filters to keep bugs and airborn crap out, felt, oiled cloth, ect, and an output fan which moves something like 10x the volume of the air in the room every hour.  The lights stay warm, but I have touched a hood by accident and didnt get burned, and I think that also leads to a longer bulb life.

Just a contribution to those of you making your rooms, or (as I am) always working (sometimes just in my head) on ways to make the room better.
Guru_Gil


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## LaserKittensGoPewPew (Apr 11, 2007)

indeed. I was planning on hooking up 1 8" inline fan to low air over a single 600w. At the other end of the fixture I was going to hook up another 8" inline fan to **** all the air out. Think this would be enough to keep it cool? I don't have the space for a 12".


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## tango420 (Apr 11, 2007)

what did you tell the people asking about the noise?


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## hgih (Apr 12, 2007)

i think you should be using a light tight way of putting up a wall oltomnoddy something like panada film or mylar you dont want light leaking in during the dark periods


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## guru_gil (Apr 16, 2007)

I think that the single inline for the one 600 should be fine.  Make sure you can seal off the bottom with a lense, as they are calling the piece of glass that protects the bulb from contamination, as well as sealing off the bottom (for a given value of "sealing off") and allows you to pull cool air from across the bulb and down the ducting, out the back of the fan and outdoors.  I also reccomend one of those dial-a-speed adaptors which allows you to turn up or down the fan RPMs, to really find a sweet spot, as the "either ON or OFF" choice can be  a bit loud on full blast on.
Tango,  I live with wife and no kids on land we bought in the boondocks, and the room is in the far back of the house, so on the rare event someone would be coming over, I could 1) slip back and dial down the fan to an almost silent whisper, allowing that this cuts down in its effectiveness a whole lot, or since the room was adjascent to my bedroom I do not usually have people back there, I just gesture and say 'thats where my bedroom and office is and its a mess, sorry but inside me is a slob screaming to get out," or something.  My rule is a simple one, NO ONE I know KNOWS what I do.  And California has a legalized structure for medical marajuana, which allows for growing 8 plants or more if your doc says he feels that is called for.  Even so, keeping a secret is something two people can do, and even three, if one of them is dead.  So I dont tell anyone, and that works great for me.  No one noticed the fan when it was the overworked loud one, or at least no one did so and said anything.
Guru_gil


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