# Grow Room, Odor & Exhaust



## jonnieblaze (Sep 11, 2008)

Ok, so I'm sure this has been asked a trillion times in a number of diff ways... but Ive looked at the threads for a while and was hoping for some help...

1) why is it not beneficial for one to have an intake fan to suck in fresh air while simulatneously having and exhaust (that's obviusly smaller and has a more powerful suction) pushing/pulling out air?

2) should this exhaust be behind the carbon filter? i know im going to get killed for these questions, but this forum has so much info that i was hoping to get some pointers...

I'm trying to grow 8 plants in room that's 2.5 x 9. I know I can have a whole at the bottom (drilled in--passive intake) and another at the top (active exhaust, w/a fan, leading to the outside of the house). Would it make sense to have a small fan pulling in air (as in the intake)? I feel lke the aroma will just permeate and the airflow won't be as good....

Any advice?


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## abudsmoker (Sep 11, 2008)

If you dont draw fresh air, add co2 to the stale air to raise co2 ppm. 

If you can draw fresh air this is good. i usually use AC with no fresh air (summer)
Fresh air (winter)

Yes filter the air! Never too much carbon. Carbon filters work both ways.


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## Phinxter (Sep 11, 2008)

it is beneficial to have active air intake , its just not always necessary so to save money some people use passive intake.
i personally use active air intake however you want the intake fan to be smaller than the exhaust to keep a negative pressure inside the grow space so that any air leaks will leak into the tent instead of being forced out.
that will keep the smell in check as everything leaving the tent goes thru the carbon filter


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## desertrat (Sep 11, 2008)

jonnieblaze said:


> 1) why is it not beneficial for one to have an intake fan to suck in fresh air while simulatneously having and exhaust (that's obviusly smaller and has a more powerful suction) pushing/pulling out air?
> 
> 2) should this exhaust be behind the carbon filter? i know im going to get killed for these questions, but this forum has so much info that i was hoping to get some pointers...
> 
> ...


1) an intake fan is really not needed if you have sized the exhaust fan and passive intake properly. the exhaust fan will pull a vacuum in the grow area, pulling air into the area through any hole or crack in the area. if you add an intake fan you run the risk of pushing smells out of the cracks in situations where your main exhaust is off or tuned incorrectly.

2) carbon filters can theoretically have the air pulled through them with the filter in the room or pushed out of them with the filter outside the room. however - most filters have a screen on the outside only that prevents large particles from contaminating the activated carbon and are thus designed to pull air through them.


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## Thraxz13 (Sep 11, 2008)

Yes sir, I have an exhaust fan that my carbon filter is hooked to. I have it running threw my Vent and out the back of my Hut!! It has great suction.I Have it on a timer and it runs while the light is on and comes on a couple times a day.. I don't seem to have any odor problems yet.. Besides the fact I have a Air purifier, That will cover up 2500sq ft. Plus running it for an hour a so a day keeps the humidity under control and keeps the air from being stagnate..
Heres a few pics, They aren't the greatest, Ill take some later....


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## jonnieblaze (Sep 14, 2008)

desertrat-

i have two options w/my situation. you've given me good feedback and i appreicate it and was hoping for more....

1. i could set the grow room up in my walk in closet and pull a vacuum and have the exhaust vent to my bathroom vent (the air would have to be pulled through a few feet of the exhaust medium used (carbon filter, etc,). or, i could have a whole drilled through the top of my walk in closet wall that is directly next too the the bathroom. the dry wall seperating the two (bathroom and closet) is about 8". this seems to be a more stealth and efficient manner. i could have a few small computer fans pull the air through the hole in the wall (through/a carbon filter) and have the duct attached to my bathroom vent. 

2. i could set the grow room up in a diff walk in closet and have the exhaust lead directly out of the window. the only problem is the window is about 30 feet from a sidewalk and gets a moderate amout of foot traffic. ive seen several people w/ sep window units/other devices so i dont know if t'd look odd from that distance or not. im on the seond floor so most likely, it wouldnt look odd. my concern is the odor. would anyone walking by just be blasted w/it? 

option 1 seems to be more stealth, but more costly and also my have lingering smoke (would the bathroom vent be strong enough to continue venthing the odor that's being pulled from the exhasut fans to get it there?--exhaust fans pull air from walkin closet, through carbon filter, attahed large duct to bathroom vent). option 2 seems to have a better "in area ordor" control, but i'm conerned about what it will smell like directly outside the window.

what would you do?


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## desertrat (Sep 15, 2008)

a few ideas - option 1 won't work unless you seal off the bathroom vent because much of the air will go into your bathroom when the bathoom fan is off and you can;t run those things all of the time. even a guest turning it off would be a problem. secondly, the bathroom vents somewhere outside anyway.

option 2 - 30 ft away, second floor, carbon scrubber - sounds like it would work.

bottom line - you can make either option work so i would make my room decision based on other questions - stealthy location in the house, availability of sufficient electricity, access to water and the such.


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## jonnieblaze (Sep 24, 2008)

I am going to have to vent the exhaust via some sort of air tight medium (i.e. dryer hose) about 12 feet long. the hose will extend from the exhaust of the grow room at the top of the door to my window. i will have a powerful fan for the exhaust, pulling a vaccumm and exhausting the air through a carbon filter, then passed along through the "medium" (dryer hose), and eventually out of the window. question--should i set up another series of fans right in my window? does this make sense? the hose would extend to the window, and open in a large rectangular fashion, that would perfectly fit around 3 mini fans in the window. this way, i am making sure the odor is getting vented thoroughly and no air is stagnant. should i have another carbon filter at the vent section (before the fans in the window) as well?


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## desertrat (Sep 25, 2008)

fans in the window are a good idea but you shouldn't need the second carbon filter.


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## jonnieblaze (Sep 26, 2008)

Thanks for all of the info!

I am considering using the following hose that will extend from my grow room to my window:
Bendaway S - www.ducting.com

Also, for those of you who grow in "tents"--where does the exhaust vent the air? Outside? Are you venting through a window or is the air already odorless since it's going through a carbon filter? Hopefully I'm making sense here. I'm a NOVICE!!! 

Thanks!!


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## rollupthatweed (Mar 22, 2010)

desertrat said:


> 1) an intake fan is really not needed if you have sized the exhaust fan and passive intake properly. the exhaust fan will pull a vacuum in the grow area, pulling air into the area through any hole or crack in the area. if you add an intake fan you run the risk of pushing smells out of the cracks in situations where your main exhaust is off or tuned incorrectly.
> 
> 2) carbon filters can theoretically have the air pulled through them with the filter in the room or pushed out of them with the filter outside the room. however - most filters have a screen on the outside only that prevents large particles from contaminating the activated carbon and are thus designed to pull air through them.



this has been the first post i found here with some information for my problem... i currently have 6 trainreck and 2 white rhino on a wilma 8 pot dripper system (hydro), my grow room measures about 140cm long/ 100cm wide, im using a 400W Mh, exaust fan 125mm and carbon filter, 100mm intake fan, advance nutrients.
(MY PROBLEM) im now on the 8th week of veg and plants have starting to stink my house up and i cant stop the smell from leaving the grow room and this is bad for many reasons... what do you think im doing wrong do u think is my intake fan is causing the smell to leave through the gaps please help as if i cant sort this out soon i'll have to curt them down. thanks in advance.


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