ventilation

Ccoastal

Active Member
it aids in venting.. pulling as much volume as the fan can handle.

i use a 340cfm 6" fan to vent my 6x10x8 veg room (480cf) , this means at full speed my fan will clear my room in under a minute and a half.

you want the fan to evacuate the room in less than 5 minutes, which allows me to dial down my fan.

you also want the intake fan to be around 1/4 the strength of the exhaust in order to get ample negative pressure. meaning if your exhaust fan is 400cfm your intake should be 100cfm.

hope this helps.

Ccoastal
 

doctor.j

Well-Known Member
so about how many cfm should i have in my 1.5x3.5x3.5 cab, i just built it last week and haven't put any ventilation in yet, been shopping around for the right fan for the right price
 

Ccoastal

Active Member
well that adds up to 18 cubic feet, meaning your exhaust could be as little as 4cfm.... micro status. a pc fan would most likely be enough for that small of a space, radio shack has some for under 30 bucks

Ccoastal
 

ShLUbY

Well-Known Member
Oh kick ass, I can get them cheap, I've had my eye on a 60 something PC fan for around 15

that should do the job for that little cab, and you dont need an intake fan.... just a hole in your box that air can come through. If you're pulling air out... its naturally gonna pull air in through the hole you made (if your box is sealed well) so let physics do it's job and skip on the electricity a bit
 

doctor.j

Well-Known Member
So too much air moving through the cab won't have a negative effect right? my last cab was so big and I had so few lights that heat wasn't a problem, I just had a circulating fan, but in this one it's sealed 100% and 4 hours with the doors closed went up to 95
 

doctor.j

Well-Known Member
Also, would it be better to put it on the top or just up high on one side, gonna put a scotch brite pad or something similar to filter out light so that won't be an issue, my intake hole will be at the bottom in the back where it will pull cooler air from the very back corner of the closet.
 

Ccoastal

Active Member
yes, you want the intake and exhaust to be at opposite ends of the room, allowing the air to circulate fully in the room.

Ccoastal
 

Ccoastal

Active Member
and no lol u cant have too much air moving through. as some pointed out, with a micro u wont need an intake fan, that point was for larger rooms. u can also adjust ur running temps by making the intake hole bigger to cool, and smaller to warm the cab.

sometimes if the humidity is on the rise i crank up my fans to the point that they want to pull panda wrap off the wall, if it wasnt held so well.

Ccoastal
 

ShLUbY

Well-Known Member
your exhaust fan should be at the top of your box because heat rises... and we wanna suck that pesky heat now dont we :) intake hole near the bottom/middle to help keep the pots/roots cooler

you can never have to much air moving thought the box... its the fan blowing on your plants you gotta worry about... wind burn can definitely hurt if your oscillating fan is on full blast right next to them... but air exchange.... you can never have to much :) your temps should be absolutely no lower than 62 (or your plant will slooooooow down) and absolutely no hotter than 80. the less your temperature fluctuates the happier your plants will be!
 

Ccoastal

Active Member
either or, my veg room exhaust is just a 6" thermaflow at the highest point, on the wall. but plugging it into the roof would also be just as effective.

Ccoastal
 

doctor.j

Well-Known Member
either or, my veg room exhaust is just a 6" thermaflow at the highest point, on the wall. but plugging it into the roof would also be just as effective.

Ccoastal
Thank you, +rep for you I've looked and looked and have not found a definitive answer for that specific question. Would you (or anyone else) suggest putting a little slider over the intake hole to control temp?
 

Ccoastal

Active Member
that is a perfect idea! i actually have a friend over at grasscity that did just that, to amazing results! it worked very well durring the summer to winter transition.

his wasnt very big either. jsut remember to keep your dark time durring the daylight hours in order to have more stable temps. (keeping the light on at night holds temps higher, and light off during the day keeps them cooler) i run flower from 7-7 at the earliest, but i like it from 9-9 because then the morning has some time to warm up before the light shut off.

Good luck man! keep us posted!

Ccoastal
 

doctor.j

Well-Known Member
Good luck man! keep us posted!

Ccoastal
Sorry sinister, I kind of hijacked your thread, I hope you got the answers you were looking for

@Ccoastal
I veg 24/0, it keeps them short, and the growth/time ratio is greater, I really want to run my 12/12 at night but that gives me a very small window to care for them. If low temp does happen to turn into an issue (doubtful, I'm in southern U.S.) what else do you suggest to keep it warm at night?
 

Ccoastal

Active Member
location location location! keeping the grow cab in a warm area like in a bedroom or closet indoors as opposed to a garage or shed will do wonders, especially if temps are extreme. even better yet, if you have a thermostat you can set it to 74* and let her roll! but if u absolutely must keep it in a garage or something, check into propagation mats, or small heat blankets like a dog would use, they both work extremely well to keep the root system happy :D

Ccoastal
 
Top