Exhaust or intake fan?

[beboggled]

I've just got one door opening to the grow room, and i can't go lose on the walls (i dont own the apartment) so im stuck with the one door opening.

Is an exhaust really more important (as some guides say), i have two large fans blowing in fresh air onto the plants, so the room/lamp is cool enough.

Logically i'd say getting in new, fresh air is more important than blowing out the warm air, or am i missing something?

 

[PkRipper]

as long as you dont run over about 75-80 degrees then you should be ok wich ever way.
co2 is a big factor when setting up vents, most folks use an enviromental controller to turn exuast fans on and off to save power and to let the timmed intervals of periods where the room is full of co2 gas, to also save the gas from being blown straight out of the room as soon as its introduced.
if your temps are high becuase of venting problems then co2 is the magic key you need.
to bad its a very bad idea to use co2 if you live in apartments .

 

[beboggled]

Thanks. For Co2 i use brewing yeast+sugar in 30 liter-something "tank", a hose is connected to the fan thats blowing on the top of the plants. It's hardly optimal but the fresh air should contain a bit of Co2 as well...

 

[FreezerBoy]

Blowing out the hot air is what brings new air in. Intake fans are the fastest way to positive pressure, they can bring air in at a much faster rate than it can be expelled. You better know your stuff with those things.

I'd remove the door and store it while replacing it with an el cheapo from Home Depot which you can cut up at will.

 

[Mr. Hugeblunts]

What's your setup?
What kind of light?
You need both exhaust and intake, if you have an exhaust but no intake, you create negative pressure in your area. This effectively is turning your grown room into a vacuum; this will kill your fan due to extra strain.

How are you planning on doing the exhaust/intake? Will you cut a hole in the door?

 

[FreezerBoy]

Careful here. Negative pressure is the goal, it's what we want. Vacuum bad, very very bad.

 

[beboggled]

Blowing out the hot air is what brings new air in. Intake fans are the fastest way to positive pressure, they can bring air in at a much faster rate than it can be expelled. You better know your stuff with those things.

I'd remove the door and store it while replacing it with an el cheapo from Home Depot which you can cut up at will.

Thanks, and good idea. So you think i could do an intake near the floor and and exhaust above it (as far as i can go on the door). Won't this just recirculate the "old" air that has just been pushed out though..

but i'm almost finished with this grow, i'll fix this for the next. should i turn my fans for this grow to make them exhaust the air instead? wont they suffer more from this, i mean that'd mean a serious lack of co2 wouldnt it?

 

[beboggled]

What's your setup?
What kind of light?
You need both exhaust and intake, if you have an exhaust but no intake, you create negative pressure in your area. This effectively is turning your grown room into a vacuum; this will kill your fan due to extra strain.

How are you planning on doing the exhaust/intake? Will you cut a hole in the door?

Well this is my third grow in this room, i've always used an intake fan, no exhaust at all.

It's a 600 HPS. Usualy i have 25-30 plants, the best grow (my second) i got 22g dried average from each plant, which i think is pretty decent considering the condition they're grown under.

The room is quite small (i could fit maybe 50 square pots in there, but then i couldnt reach them for watering, so i stick with half hehe.) All the walls, floor, and celing are painted in white, so there's good reflection of light in there.

I also have 3 55w (red spectrum) Flourescent lamps in there.

I'm not even sure i could do holes in the door because it'll leave the door quite suspicious to those who passes it heh, unfortunately its in the hallway so its not so discrete.. the lamp turns on at eight in the evening and thats when i open the door, i usualy dont have any visitors then so it has worked ok.

I guess i have 3 choices with this room;

* using just exhaust fan (pushing out hot air, doesnt create bad pressure in the room)
* using just intake (gets new co2 which i think is important, doesnt push out the co2 that i get from my simple co2 setup. is bad because of the preasure it creates, if i got it right?)
* using both (in the same "vertical line" since its just a door opening, which probably is a bad idea since it would just recirculate the old air, and it would blow out my co2..

 

[irieeyes808]

I am in a similar situation.

 

[Mr. Greengenes]

An exhaust fan will give a bit of vacuum, which keeps stray odors from escaping where you don't want them. If the room has normal 'leaks' under the doors and all, just use an exhaust fan and direct it where no one will smell it. Unless, the smell is not a problem. If heat is in reasonable ranges, why use a fan at all? I don't.

 

[smokinshogun]

-

 

[beboggled]

my apartment does not stink since most of the air(/smell) is pushed in to the room and not out of it. It might smell a little after 20.00 in the evening and to 8.00 in the morning when the room isnt sealed, but since i dont have visitors then it is no problem. i have friends who knows how growing pot smells, they've never said anything so i think im safe.

Mr. Greengenes: the room will be too hot with no fans, especially now in the summer.

EDIT: i could direct the fans in different positions though, the one which is blowing out i could direct up and out to the left, the intake-fan (on floor) could be directed from the lower right.. maybe that'd work ok (better than now)?

 

[smokinshogun]

-

 

[beboggled]

i didnt say that, of course it will be pushed out eventually, but not at the rate as if i had a fan pushing it out. the air/smell does not escape much further into the apartment though since there's a fan blowing it in directly, thats why smell is kept under controll (not completely maybe, but more so than if a fan blowed it all around my apartment).

in the dark period there are no fans, the humidty is in the 40's something. i have never had problems with mold or too high humidty. its pretty dry here i guess.

 

[FreezerBoy]

Thanks, and good idea. So you think i could do an intake near the floor and and exhaust above it (as far as i can go on the door). Won't this just recirculate the "old" air that has just been pushed out though..

Once old air is out of the room it's out of the room. You can't recycle what doesn't exist. Punch 3 equal sized holes in the door, two passive intakes at bottom, one exhaust above for the fan.

Well this is my third grow in this room, i've always used an intake fan, no exhaust at all. [/SIZE]

uhhh ... this guarantees positive pressure which is our mortal enemy. Negative Pressure For Dummies

my apartment does not stink since most of the air(/smell) is pushed in to the room and not out of it

No offense but, I'm not buying this for a second. You've become inured. You're begging to be busted.

 

[beboggled]

Thanks! I'll look into that guide, its about time i start reading up on that.

It doesnt smell during the days, i have a friend who is only here a few times every week for a short period of time, so he's not inured. He'd tell me in a heartbeat (he has done before when i had the lamp on during the days). Same with my parents when they visist, who also knows the smell, they wouldnt hesitate.

I'm also not in the US, most people here have never smoked pot or even knows someone who does, and even less has ever smelled growing pot.. I can understand that in US its way easier to get caught so i do understand your concern.