Ventilation

[Urdedpal]

Air ventilation and air movement is a very important part of a grow. Carbon dioxide and oxygen are so important cause they really are the building blocks of a plant. Without a fresh supply, plants become stunted and could die.Ventilation also helps to control humidity. I can go on and on about the stomas and the roots but all ya really need to know to grow is that fresh air is important. It is also the main way to help control temperatures in most grow rooms. When ever you have a indoor grow area you have to move stall air out of the room to resupply fresh air. Installing a fan in the room will only circulate the air in the room and even out the temp thru out the room. This is a good thing but you still need to remove the air out of the room. I found that inline fans and squirrel cage fans work the best. The inline fans move massive amounts of air and are very quiet but they are exspensive. Squirrel cage fans do the same thing but can be alot noisier.(rubber insulation or felt helps control noises from loud fans by installing them between the mounting area).
To set up a vent fan you need to figure out the total volume of your grow area. Lengh x width x height is the total volume.
Example :5 FT. LONG x 3.5 FT. WIDE x 8 FT. TALL =140 cubic feet.
You want a fan that will ehaust the room within 3 to 5 minutes. This is the common standard. So with a 140 cubics foot grow area you would need a 420cfm or higher. A 420cfan can remove all the air in the room within 3 minutes.
A 700cfm (cubic foot per minute) can do it within 5 minutes.
Heat rises so always remember to install exhaust fans toward the top of the grow area
I will try to finish this article at a later time.

Source:Urdedpal @ 420 Magazine

 

[CookieMan]

WHAT? so the room is 140 cubic feet, right? so shouldn't a 140cfm fan clear it out in one minute? and wouldn't the 700cfm fan atleast be faster then the 420cfm fan? maybe i'm confused and missed something but please answer, i know its an old thread but the logic seems backwards to me.

 

[Stix]

I"d agree. The math is not quit correct here. I'm thinking he messed up on his room dimensions. I would say a 70 cfm fan would be adequate for that size room. You can simply use a normal bath fan for this application, which is cheaper. That's replacing the air every 2 minutes. Ofcourse don't forget you need decent size air intake holes into the room as well. You don't wanna create a vacuum.

 

[Kalas]

"Effective treatment requires the exchange of air in the growing area in a period of 5 minutes. Compute your requirements by multiplying the width times the length times the height of your growing area to obtain the total cubic feet. Divide this number by 5 to determine the proper filter size needed.

For example, if your growing area is 8 feet long by 8 feet wide by 8 feet tall, it contains a total of 512 cubic feet. To treat this area in five minutes, you would need to use a fan with a CFM (cubic feet per minute) rating of approximately 102."