+rep to all answers.. if relative. ;)

Question about air exhaust/intake/outake


i got an 6 inch aircooled reflector/light.... so i got the two holes... on on each side of the hood.. i also got a 6 inch inline fan/6 inch ducting.

what im woundering is... this inline fan.. does it suck air through the ducting and out of the grow box? if so that takes care of the out take of the co2...

but what do i get for intake of oxygen into the closet/grow box... more ducting and another inline fan??? but switch the inline fan around or something. so its facing the other way and pushing fresh air into the closet...???

do i got this right... 2 inline fans and ducting. hooked up to the 2 slots on the air cooled reflector.... one taking out air.. one taking in air?? or am i mixed up.. do i gotta buy seperate type of fan for out take or in take..??

if your running c02 then youll want to vent the light totally separate from the grow room or area its self. if your not running c02 then, hook up your venting so its sucks air out of the grow box thru the light. this will help cool the light and vent the box all in one. yes you will need to cut a second hole in the box for an air intake but you dont always need a fan blowing in. if your exhaust is strong enough to create a slight vaccume inside the grow box your all set. use the second fan to circulate air inside and inbetween the lights and tops of the plant. youll be able to move the light alittle closer.

I think that sums it up lol

i use the negative pressure too. I and a lot of other growers. But recently I was reading a grow magazine called "Urban Gardens" and they had an article about venting. They said that negative pressure is not the best, but a small intake fan is the best way, to take some pressure off the exhaust fan. It is actually a lot of work for the exhaust to pull at neg pressure. Seemed like do something about it a lot. I have been growing for less than a year.

For mj we like the neg to save power and mostly for smell, to keep the smell inside the filters circuit. But now it makes sense to try and help as much as we can without disturbing the neg pressure.

I hope that is not to much to deal with just starting out. I use a dcut booster now as an intake and an 8 in inline as a outake, thru ozone. No charcoal. No smell either.

i use an intake fan also, i was just giveing him an example with what he has available to use at the moment. urban gardens is a good mag.

IndicaFatnHeavy said:

Question about air exhaust/intake/outake


i got an 6 inch aircooled reflector/light.... so i got the two holes... on on each side of the hood.. i also got a 6 inch inline fan/6 inch ducting.

what im woundering is... this inline fan.. does it suck air through the ducting and out of the grow box? if so that takes care of the out take of the co2...

but what do i get for intake of oxygen into the closet/grow box... more ducting and another inline fan??? but switch the inline fan around or something. so its facing the other way and pushing fresh air into the closet...???

do i got this right... 2 inline fans and ducting. hooked up to the 2 slots on the air cooled reflector.... one taking out air.. one taking in air?? or am i mixed up.. do i gotta buy seperate type of fan for out take or in take..??

Click to expand...

Attached are a couple of options for venting your box.

Attachment 1 shows the light being vented separate from the box. Requires a minimum of 2 fans, 3 if you want a fan for your inlet. These fans would be smaller, say 100 cfm for the light and a fan that is strong enough to swap the air in your box at least every 3 minutes - I would shoot for every 1 minute in a smaller grow box.

Attachment 2 shows the light and box being vented together. This requires a minimum of 1 fan, 2 if you want a fan for your inlet. The fan has to be strong enough to cool your light and vent the box at least every 3 minutes.

As far as a fan on the inlet, tea tree is right. You either need to make sure that your inlet is big enough to allow air in without stressing the exhaust fan, or help the exhaust fan with an inlet fan that is close to the same cfm as the exhaust fan. A fan that is sucking hard is a fan that is noisy.

I have my intake fan on the outside of my tent, with duct connecting to it and running to the inside of my tent.

Then I have my other fan inside my tent, with duct conencted to it, running to the outside of the tent (my exhaust fan). Seems to be working like a charm.

Skoad said:

I have my intake fan on the outside of my tent, with duct connecting to it and running to the inside of my tent.

Then I have my other fan inside my tent, with duct conencted to it, running to the outside of the tent (my exhaust fan). Seems to be working like a charm.

Click to expand...

I have my veg box setup this way, but it's really quite a bit less efficient than doing it the way pictures are above. The less ducting the more efficiently things will be running.

I personally like to cool my light seperate from my room, just seems to work best for me. I use about 1/2 the CFM for my intake fan as my exhaust fan so that I can maintain negative pressure.

ok ill plus rep to all of u.. .but not 2 be rude.. but ur kind of ignoring the basis of my question

i just get 2x inline fans and have 1 for outake and 1 for intake??
Do i just reverse the position of the other fan for the intake?
Or do i have to buy a different kind of fan?

My set up will be more like the FIRST picture in dystopias post

ty

just reverse the other fan so that one is sucking air in and the other one sucking it out-just flipit man....

It's not that we haven't answered your question, it's that you have options we are trying to explain.

If you currently only have 1 6" inline fan you should set it to suck air through the light. So hook the fan up inline after the light and have it suck the air from the room through the light. Then make sure you have an intake hole so that it can draw the air in. The room will have negative pressure from the fan so that hole will draw air in.

If you have 2 fans you have 2 options. You can setup ducting on the light so that one fan sucks air through the light and straight out of the box. The other side of the ducting on the light would be connected to just a hole. Again negative pressure will draw cool air into the light. Then you would have a carbon filter inside the room above the light that would would draw air from the room out through a hole. Another hole in the grow room down low to draw in cool air (negative pressure from the fan in the room this time will do this).

OR

If your fan is working too hard in either of these scenarios you may need to an intake fan (by just turning the fan the other way) on your intake hole to relieve some of the negative pressure. This happens when you have too much negative pressure caused by a large fan in a small room.

You can obviously exhaust the room, through the light and use a second fan as an intake to relieve the pressure if what you currently have is one beastly fan.

So really it's going to depend on the size of the room, the size of the fan you currently have and how much negative pressure is going to be generated.

IndicaFatnHeavy said:

i just get 2x inline fans and have 1 for outake and 1 for intake??

Click to expand...

If you're going to use the first diagram, you would need ONE fan to exhaust the light, ANOTHER fan to exhaust the box (2 total), AND EITHER a passive (no fan) inlet that is large enough to allow enough air into the box without stressing the box exhaust fan, OR ONE active inlet fan that is sized at 50 - 75% of the box exhaust fan's cfm (3 fans total IF using this option).

IndicaFatnHeavy said:

Do i just reverse the position of the other fan for the intake?
Or do i have to buy a different kind of fan?

Click to expand...

If I understand your question correctly, position the fan so that it is blowing in the direction of the arrows in the diagram. You don't need to buy a special fan, just reverse it to give the air flow direction you want.

ty dystopia.

whats the point of an inlet... what is this talk of negative space/air

IndicaFatnHeavy said:

whats the point of an inlet... what is this talk of negative space/air

Click to expand...

If you put a fan in a room that room has x amount of air in it. If you put a fan in that room and connect it to an exhaust without an intake (either passive or forced) you're going to to develop negative pressure, basically a vaccuum. You want a decent vaccuum in the room, but not too much. You want to control how much vaccuum there is if that helps.

Suck the air out of a soda bottle with your lungs and you creative negative pressure in the soda bottle. Poke a hole in the other side of the bottle while you are sucking and you'll relieve the negative pressure by allowing air into the other side of the bottle. Bigger the hole, the less negative pressure.

Where's my +rep damnit? Haha...I'm kidding. I just love that people try to bribe answers with +rep.

laserbrn said:

Where's my +rep damnit? Haha...I'm kidding. I just love that people try to bribe answers with +rep.

Click to expand...

I'm looking for some reps too lol

All you usually need is a passive intake, which is just a fancy name for a hole in a wall or door, that usually has a louvered vent on it - that draws are in "passively".

oook.. thanks... +rep to both of u..... the water bottle example really cleared my head about what it is...

and 1 more question for more rep possibly..


-Grow boxes is one thing... but what about a closet grow.... i obviously cant cut a hole in my closet door.... but then i sure as hell cant open the door... due to the fact that i might get hermies.. what do u do if ur growing in a closet?

Actually, Its really not smart to exhaust the grow room through the light! First of all, you're heating up stanky air, and making it that much stankier, secondly you'll dirty your bulb with all the essential oils and humidity and dust etc in the area, and thirdly you're trying to cool it using already heated air..
As for position, you do want it exhausting, not pushing it in.. This puts any turbulance in the duct, and allows laminar flow across the bulb which is BY FAR the best approach.. And do not use a fan on both ends or you'll create a turbulance issue unless its calibrated perfectly.. Urban Gardens be damned, its basic HVAC theory..
And do your best to keep everything as straight as possible.. try to avoid sharp turns in the ductwork..

born2killspam said:

Actually, Its really not smart to exhaust the grow room through the light! First of all, you're heating up stanky air, and making it that much stankier, secondly you'll dirty your bulb with all the essential oils and humidity and dust etc in the area, and thirdly you're trying to cool it using already heated air..
As for position, you do want it exhausting, not pushing it in.. This puts any turbulance in the duct, and allows laminar flow across the bulb which is BY FAR the best approach.. And do not use a fan on both ends or you'll create a turbulance issue unless its calibrated perfectly.. Urban Gardens be damned, its basic HVAC theory..
And do your best to keep everything as straight as possible.. try to avoid sharp turns in the ductwork..

Click to expand...

Doesnt seem to be a huge problem... that slike telling the difference between a dual and normal processor... just not a big problem.. needle in a hay stack.

ull also have the cool air going in and over the bulb also... so w.e.... and easy to clean the bulb after a grow.. or even on the night cycle.


but can some1 answer my above queestion about closets

IndicaFatnHeavy said:

Question about air exhaust/intake/outake


i got an 6 inch aircooled reflector/light.... so i got the two holes... on on each side of the hood.. i also got a 6 inch inline fan/6 inch ducting.

what im woundering is... this inline fan.. does it suck air through the ducting and out of the grow box? if so that takes care of the out take of the co2...

but what do i get for intake of oxygen into the closet/grow box... more ducting and another inline fan??? but switch the inline fan around or something. so its facing the other way and pushing fresh air into the closet...???

do i got this right... 2 inline fans and ducting. hooked up to the 2 slots on the air cooled reflector.... one taking out air.. one taking in air?? or am i mixed up.. do i gotta buy seperate type of fan for out take or in take..??

Click to expand...

just switch one around and your all good bro