Need to cool my room!!???

i have a metal grow cabinet that is 4ft tall 3 1/2 ft wide and 2 1/2 ft deep witha 400 watt HPS. i dont want to get a new hood i just want to be able to pull the hot air out HOW BIG OF A FAN SHOULD I GET SO I CAN CLOSE THE DOOR ON THE ROOM??

i would say stay on the safe side and get a good vortex 6in 449cfm..it will pull alot of air out and hopefully maintain a good temp

that fan may be too much but its better to be safe then sorry

I would say something like 65 cfm really.. you dont need anything too much... unless it gets ungodly amounts of hot in there

then do something like 120 or so... but you dont really need much for such a small space

Stick Twistyman In there ,, He is cool as Ice ...

mr.red said:

I would say something like 65 cfm really.. you dont need anything too much... unless it gets ungodly amounts of hot in there

then do something like 120 or so... but you dont really need much for such a small space

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You obviously are not running an hid inside a cabinet. 65 cfm wont do shit to a 400w. I run a 300+ cfm 6" fan to a carbon scrubber to keep my cabinet under 85f when lights are on. I have been doing HID cabinets for over a year and closets before that. You actually need more ventilation in small spaces then you do inside of a whole room.

so if i have a 5ft by 5ft by 8ft tall room, how much air should i move to keep it cool enough with a 400w HPS? the reflector i have dosnt have a duct attactment, should i find a hood with this? or is it possible to bring the duct in at the ceiling level with a powerful inline fan do to the trick?

well it get over 100 in about an hour in my room with the doors closet and i have a fan pulling air right now i think i whould just go big if i get something to small then it will be worth nothing and to drop a temp down 20 degrees it would have to be somethin real strong im lookin around 200 any prefrences

Sadistic Incubus said:

so if i have a 5ft by 5ft by 8ft tall room, how much air should i move to keep it cool enough with a 400w HPS? the reflector i have dosnt have a duct attactment, should i find a hood with this? or is it possible to bring the duct in at the ceiling level with a powerful inline fan do to the trick?

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Thats a much bigger room. IME larger spaces take longer to heat up and therefore do not require as much venting as the smaller spaces. As long as you had about 200 cfm (a 4" centrifugal inline would probably do it) fan and scrubber I would think you would be fine. That should cycle the air out of your room within a few minutes. I use one of these:
http://www.buyextras.com/thermostatic.html

This way I can set a temp and the exhaust only kicks on when its too warm. You should have a fan blowing over your plants too to keep air moving around in the room.

If you have a passive intake and an exhaust that vents outside of the grow room You will be fine with that room.

BTW, that room is a little big for a 400. 3'x3' is the most "usable" area of light from that fixture.

Haha, sorry no I haven't been growing in such a small space.

Excuse my ignorance. I was only thinking of the cubic footage and not the light and filter as well.

thats for the advise i think im going with a 400+ CFM canfan i have an in take and out take hole the fan now that is outaking is just not doing it for me and if i put any other size of light it would get over a 100 with the doors open i mean it gets 80-90 degrees open now

mr.red said:

Haha, sorry no I haven't been growing in such a small space.

Excuse my ignorance. I was only thinking of the cubic footage and not the light and filter as well.

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NO Problem

gottagrow69 said:

thats for the advise i think im going with a 400+ CFM canfan i have an in take and out take hole the fan now that is outaking is just not doing it for me and if i put any other size of light it would get over a 100 with the doors open i mean it gets 80-90 degrees open now

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I have a 400 hps in a smaller cabinet vented with a 300 to a scrubber. The cab stays 5-8 degress warmer than the room. Take it easy, and good luck working out the heat issues. Post pics when you get that thing all built!

you need to replace the hot air your pulling out bro... if you have 4 by 3.5 by 2.5 that is 35 CFM if you do the so you want to exchange about 2-3 every minute.. so your looking at 105 CFM, now take into consideration if your adding a scrubber or pulling from an air cooled hood you need more. Also whatever air your pulling out must be coming in to have a proper ventalation system... I would recommend looking into a cool air hood or tube as it may reduce your heat about 10-15 degrees.

I had a batwing bought a air cooled hood and a booster fan. Dropped 20 degrees F in my closet grow. It was about 150. I upgraded my lighting and cooled my room so it was cool and i didn't have a loud noise. You can buy those cheap inline fans but you get what you pay for.... IMO... GL

Thats roughly 48 cubic feet of space.Now consider ducting size and heat retention from the metal unless you insulated it correctly. Will you use a carbon scrubber? If so double the cfm so your at 96 cfm needed figuring 3 inch ducting or no ducting.you ll want a second fan bringing in cool air from outside the cabinet about 50 cfm is fine in this size cabinet.Add more cfms for each size up you go in carbon scrubbers double the cfm for ever 2 inch in diameter scrubber you go up

wow lots of good info, thanks! I put my studs up and i dont have quite that big of space after all... i am NOT a carpenter and i didnt realize how much work was really involved in building this. I have a 3ftx4ftx6 1/2ft tall, so the room is a bit smaller, bigger then the closet i was growing in. Passive air intake from ground level, i will be exhausting into my eve ducts, this building is far from foot traffic, is a carbon scrubber nessassary?

Your set up sounds like mine, but mine is wooden. I tried the exact same thing to maximize the usage of the light and found that my temps are a lot cooler with a cool tube. Check out my DIY Cool Tube and look at my box to see it in action.

thanks for the advise everyone i bought a can fan for like 135$ and i can now close the doors noticed alot more growth in the last couple days those can fans are the real deal

You can think me later:
http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&catalogId=10053&productId=100211785&N=10000003+90401

145 cfm will be plenty for what you need in there. I would get 2 of these. 1 for intake, 1 for outtake.