Window fans strong enough for tent exaust?

drekoushranada

drekoushranada

Well-Known Member
I am wondering if the lasko twin window fans will be strong enough to make negative pressure in my 5x5 tent. They are sold at Home Depot. They say the are rated at 1300 cfm but I doubt that. If they are half that strong it would be great bc I have to exhaust out the window. So I will be able to kill two birds with one stone. What Do you all think? As always thanks in advance.
 
zvuv

zvuv

Active Member
Are you exhausting through a carbon filter?

The cfm of a fan is only part of the story. Usually this rating is measured by running the fan in open air with very little resistance or back pressure. The other spec is 'static pressure' which is a related to how much pressure a fan can deliver to overcome back pressure from a constriction like a filter. It's like the difference between, say, flapping a blanket which moves a lot of air at low pressure or a bicycle pump which delivers much less air but at much higher pressure.

Personaly I doubt a window fan will move much air through a carbon filter. OTH your grow space is small and it may be enough.

If you have a use for the fan anyway, even if it doesn't work, why not try it. Otherwise I suggest a 4" or 6" inline duct fan

for example:
http://www.amazon.com/LED-Wholesalers-GYO2402-Hydroponic-Booster/dp/B003YFADW8/ref=sr_1_1?ie=UTF8&qid=1307289712&sr=8-1
 
H

HSA

Well-Known Member
Drekoushranada: If my sixth or seventh grad math is correct a 5' X 5' tent usually 6' 6" tall has a volume of 1,675 cubic feet. If you want to change that air every three minutes you're going to need a fan capable of moving approximately 558 cubic feet of air per minute.

Now comes the real tricky part. If you're going to push it or suck it through a carbon filter you're not likely going to get away with a cheap fan. You're over three times bigger than the cabinet grow I'm setting up and unless you want it to sound like you have an piston/prop airplane in your room you're probably looking at a Can Fan. Whether my new four incher would work I couldn't say. I know it's over kill for my cabinet but it might not be enough for your tent. One thing I do know is that it's whisper quiet. Zvuv is right, the CFM's are only part of your problem.
 
D

drcheat

Member
HSA said:
Drekoushranada: If my sixth or seventh grad math is correct a 5' X 5' tent usually 6' 6" tall has a volume of 1,675 cubic feet. If you want to change that air every three minutes you're going to need a fan capable of moving approximately 558 cubic feet of air per minute.
Click to expand...
is that american math?
normal math is 5x5x7=175 cf.
That fan will pull more than enough air through that size a room. But i have a few of those at home and they are too large and not suited for exhaust for a tent. It would be too hard too keep it light proof during dark. And would be very hard to hook it up to a carbon filter, if even it would work, as mentioned above. Get an inline duct fan. They are pretty cheap.
 
drekoushranada

drekoushranada

Well-Known Member
zvuv said:
Are you exhausting through a carbon filter?

The cfm of a fan is only part of the story. Usually this rating is measured by running the fan in open air with very little resistance or back pressure. The other spec is 'static pressure' which is a related to how much pressure a fan can deliver to overcome back pressure from a constriction like a filter. It's like the difference between, say, flapping a blanket which moves a lot of air at low pressure or a bicycle pump which delivers much less air but at much higher pressure.

Personaly I doubt a window fan will move much air through a carbon filter. OTH your grow space is small and it may be enough.

If you have a use for the fan anyway, even if it doesn't work, why not try it. Otherwise I suggest a 4" or 6" inline duct fan

for example:
http://www.amazon.com/LED-Wholesalers-GYO2402-Hydroponic-Booster/dp/B003YFADW8/ref=sr_1_1?ie=UTF8&qid=1307289712&sr=8-1
Click to expand...
Well in my case I will not be using a carbon scrubber just a CAP ozone generator in the duct.
HSA said:
Drekoushranada: If my sixth or seventh grad math is correct a 5' X 5' tent usually 6' 6" tall has a volume of 1,675 cubic feet. If you want to change that air every three minutes you're going to need a fan capable of moving approximately 558 cubic feet of air per minute.

Now comes the real tricky part. If you're going to push it or suck it through a carbon filter you're not likely going to get away with a cheap fan. You're over three times bigger than the cabinet grow I'm setting up and unless you want it to sound like you have an piston/prop airplane in your room you're probably looking at a Can Fan. Whether my new four incher would work I couldn't say. I know it's over kill for my cabinet but it might not be enough for your tent. One thing I do know is that it's whisper quiet. Zvuv is right, the CFM's are only part of your problem.
Click to expand...
Well I just wanted to keep it stealth instead of having some contruction grade styrofoam in my window with some holes cut in it. I figured the mod to the fan will take care of both.
drcheat said:
is that american math?
normal math is 5x5x7=175 cf.
That fan will pull more than enough air through that size a room. But i have a few of those at home and they are too large and not suited for exhaust for a tent. It would be too hard too keep it light proof during dark. And would be very hard to hook it up to a carbon filter, if even it would work, as mentioned above. Get an inline duct fan. They are pretty cheap.
Click to expand...
The idea with the inline fan is not a biggie. I can grab a 8" High output Can fan rated at 732cfm for $120 or less. I have a buddy that has it. Now will that be overkill.. I think so but I happen to like overkill. :D I will just grab that thing and call it a day. Just have to rig something up for my window. Plus I am certain it will handle the temps from 1600Kw that will be pumping in the tent. +REP to you all.
 
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