Grow Room 101 - Ventilation

[ChanChan203]

New grow 101 topic page over CFL grow lifhts



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[ResinSaurusRex]

I was thinking of going active air intake but im not sure if i need it now. The tent is 2ft D x 4ft W x 5ft H. The exhaust fan is a 440 CFM with a carbon filter. I have a 20" L x 4" H and 2 12" L X 4" H side and rear vents on the bottom of the tent near the drip catcher. The 440 CFM will be mounted inside the tent on a low setting.

I was going to put an active 440CFM blowing fresh air but i think that would be overkill since ill have a clip on fan for circulation and the 440 exhaust fan has more than enough power to suck the air out and refill the tent.

Thoughts??

 

[ChanChan203]

I was thinking of going active air intake but im not sure if i need it now. The tent is 2ft D x 4ft W x 5ft H. The exhaust fan is a 440 CFM with a carbon filter. I have a 20" L x 4" H and 2 12" L X 4" H side and rear vents on the bottom of the tent near the drip catcher. The 440 CFM will be mounted inside the tent on a low setting.

I was going to put an active 440CFM blowing fresh air but i think that would be overkill since ill have a clip on fan for circulation and the 440 exhaust fan has more than enough power to suck the air out and refill the tent.

Thoughts??

That should be plenty of passive air intake and as far as an active air intake u never ever ever want a active air intake as big as ur air outage that a major mistake u want a some what negative pressure in your tent so for one it doesn't bulge out and two it help capture all of the smells and seal up and small leaks around the seams

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[ResinSaurusRex]

Great thread!
Look forward to following along on this one.

Forgive me if I'm jumping the gun in the lessons, if this is coming up I'm happy to wait it out.

Curious people's thoughts on fan pushing through air cooled hoods vs pulling.

I've read conflicting sides and have tested it both ways, only thing I believe to be an upside to pulling is the suction created helps to seal the light, vs pushing expands the seals lowering the air cooled hoods efficiency.

I've read that pulling creates excessive heat in the motor, reducing motor life. That seems believable.

I've update this setup since but it's bed time for the ladies and didn't want to disturb their rest to snap a picture.

I have a question about that set-up. With the understanding that hot air rises, should you be pushing heated air through your light and on out the tent?

For efficiency and maybe to help save some bulb life shouldnt you be pushing fresh cool air from the outside of the tent through the light? If you only have one inline fan you could get a booster fan for the light.

The filter can be mounted where it is and run some ducting from it on through the top and out the tent. Attach the inline to the ducting and put it on the floor opposite side the air going into the light. Buy a dual digital timer for the ballast and booster fan so both turn on and off around the same times. Booster could go off a few minutes after the light goes off.

Use passive air intake to filter the stale air.



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[Ego11]

That was taken before I switched it over.
This is what it looks like now.

There is probably way more efficient ways to achieve better ventilation. Ideally a fan for the filter and a separate fan for the light would improve the efficiency, and cool air being pulled over the light, however I purchased a whole setup piece by piece, made a few mistakes from lack of knowledge and ended up having to purchase different equipment needless to say it wasn't cheap.
Noise was a concern to me so I kept the fans to a minimum.

I do have a plan to create a cooling system using filtered outside air, temperature controlled relays and a booster fan. Simple but effective. This should help drastically to improve temperatures and cooling to the light. For a very reasonable price with very low power usage. I will be installing it this weekend.

 

[Beleaf]

How cool can the air be that's pulled passed the bulb?


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[ChanChan203]

How cool can the air be that's pulled passed the bulb?


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Pretty cold idk an exact temp cause the most depends on like wattage how hot the bulb is but I've seen people run chilling before thier hoods so I mean ik that could lower Temps dramatically

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[Beleaf]

Pretty cold idk an exact temp cause the most depends on like wattage how hot the bulb is but I've seen people run chilling before thier hoods so I mean ik that could lower Temps dramatically

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Thanks! The problem I'm up against is I'm using a 1k dimmed to 500 and just recirculating the air in the small room where the tent is. It's working great temp wise but I have no outside air. Any air coming in would be close to outside temperature.


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[oldnoob]

I wonder if i could pose a different type of question? What is the minimum air exchange necessary for good growth? The heat issue i have is opposite from almost all growers i see on this site. I need to heat my space in a stand alone shed outside in the north country. Just came through a cold spell of -20C. Heating that much air would be impossible not to mention expensive.

Thanks for your input!

 

[ChanChan203]

I wonder if i could pose a different type of question? What is the minimum air exchange necessary for good growth? The heat issue i have is opposite from almost all growers i see on this site. I need to heat my space in a stand alone shed outside in the north country. Just came through a cold spell of -20C. Heating that much air would be impossible not to mention expensive.

Thanks for your input!

OK well if u having trouble keeping heat have u considered doing a sealed grow room and using co2 enrichment?

cheers yall and remember keep'em frosty

Large dual chamber grow box build

 

[jr21]

Heyy back again today with our next topic of conversation which is passive vs active intake in any type of grow space. But before I begin I'm gonna give shout out to my man Pigeons420 who inspired me to begin these pages this for you man!!!

So what is passive and active air?? Passive air is allowing free flowing air to enter the room through the natural negative pressure that your room has with the exhaust fan going. Active air is forcing air into room with a separate intake fan. Now you question probably is which of theses systems is better? Well neither has been proven to be better than the other one in general it just all depends on cost and way room is set up. The general idea of both of these setup is to all air while keeping a NEGATIVE pressure in your grow this prevents smells from leaking and air existing out other places.

So first we will cover passive air passive uses and exhaust fan and just standard holes to allow fresh air to come into but how much is enough?? In a passsive air system you air intake hole or holes should be at least 3 times size of intake hole when added together and still be filtered I would suggest cutting an air filter used on house ac system at least 2 to 3 layer to prevent insects and other debris from comming into room.

Now onto passive air intake your fan cfm needs to configured as 75 percent of total cfm of the exhaust cfm you figured up in Mondays post to keep that negative pressure where it sure be and should be filtered coming into your room just as your exhaust does out of room.

As always pics comments and discussion is always welcome and always always keep it frosty you guys!!

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Hey Chan,

Thanks for starting this up... ive been researching like crazy to get a grow room started. Please keep it going...

The size of the room I want to work with is 9ftL x 9ft W x8ft H. So my cfm is 216 *1.25 = 270 cfm. To create a negative pressure room I divid 270 by 75% to get 360 cfm exhaust fan size. Then I make make 3, 6" or 8" holes in the room for air intake. Those are pretty big holes. Where do you put em? Door? Can the A/C or air from A/C provide sufficient air intake?

Thanks

 

[ChanChan203]

Hey Chan,

Thanks for starting this up... ive been researching like crazy to get a grow room started. Please keep it going...

The size of the room I want to work with is 9ftL x 9ft W x8ft H. So my cfm is 216 *1.25 = 270 cfm. To create a negative pressure room I divid 270 by 75% to get 360 cfm exhaust fan size. Then I make make 3, 6" or 8" holes in the room for air intake. Those are pretty big holes. Where do you put em? Door? Can the A/C or air from A/C provide sufficient air intake?

Thanks

A basic 300 cfm should work fine for u and there many different ways u can make intake holes yes a ac system will pull air as if an intake but it is not enough to do it on its own is your 9x9 room a bedroom or where is located that will help decided intake locations a lot better hoping to hear from u soon

 

[CookieMan]

Hi, I thought I would add a data point to your thread. I have a 4x4x6.5 ft tent. It has passive intakes with screens for "filtration". The screens will allow light into the tent. Using three of the lower circular duct entrances open the tent will still bulge in a lot, and this makes the overall volume of the tent significantly lower. Using a 440cfm fan and 6" carbon filter on the exhaust, I was worried about the lack of space and the long term effect of such high negative pressure on the tent. I also was not willing to except like leaking in or out of this tent as it is for flowering. I purchased the exact same filter and fan combo to use as an intake fan. I figured that I would just back the speed off slightly to have neutral pressure, which from studying air cooled computer cases is ideal from a cooling perspective.

The tent was going to explode with the intake set at 50% speed. I had to turn the dial down to the lowest setting to have a neutral air pressure. However, using a Y-split and dividing the air between a cabinet half it's size didn't create neutral air pressure in the tent. I had to stuff the cabinet duct with filter cloth and carefully tape the duct shut to find the right restriction to neutralize the pressure in the tent. The cabinet still has a decent negative pressure, but the doors don't suck shut as hard as before.