It's getting hot in here.

So I built this grow cab each side is 4' high 2' wide and 2' deep. It stay's about 81 degrees F. with no light on, with light on it get's to 93 degree's F. I've got 8 41W CFL's, each one is supposed to be 200W equivalents. The lights are in my custom box with two fans up top and two on the sides to exhaust the heat. Then I have 4 more fans on the top of the grow cab for exhaust and 4, 5" passive air intake holes on the bottom of the cab. I know my temps should be about 85, but I can't get them any lower then 93. I've tried different configurations with the fans in terms of blowing or exhausting the air and still 93 is the lowest I can get it.

The four fans on top are rated at 54cfm's each for 216cfm. and the four exhausting from my light hood are rated at 68.54 each for 274.16 cfm, so in theory I'm moving 490.16 cfm. So why is my room so hot? Any ideas how I can lower my temps?

Thanks.

Those fans really dont move as much air as they say they do. You need to get an inline fan they cost alot. Maybe with that small box you could get away with a duct booster they're really cheap but also don't move as much air as they say they do.

Without ducting those fans arent going to move that heat very far. I use those fans on my tent but I am in a loft next to a window. In a closet I imagine you wont be dissipating much heat.

Is the cabinet air tight? Where does the passive intakes get their air? Looks like it might be pretty solid under there.

I agree, try a duct booster, it should vent that nicely, and less noise.

I like the hood, but i think it could possibly be causing some airflow issues.

And wow, 81deg with the lights OFF??? You've definitely got to change your intake temp. You should expect a 10-15 deg increase with lights on using PC fans.

Yes the cabinet is air tight. I drilled 4, 5" holes at the bottom for the passive intake. would I replace each fan with a duct boster? Or would I use it light hood to ducting to duct booster to exhast the heat directly from the light and maybe keep the four exhaust fans up top for general cab cooling?

pc fans suck balls, just from my experience. get something stronger

So if I got an inline fan, would it be best to just use the fan to straight exhaust the heat from the hood out side the cab? I could do that and use the four pc fans up top for cooling? What would be the best thing? I'm not relay trying to drill to many holes in the cab.

I would move a couple of those PC fans to the intake.

High on the moon said:

So I built this grow cab each side is 4' high 2' wide and 2' deep. It stay's about 81 degrees F. with no light on, with light on it get's to 93 degree's F. I've got 8 41W CFL's, each one is supposed to be 200W equivalents. The lights are in my custom box with two fans up top and two on the sides to exhaust the heat. Then I have 4 more fans on the top of the grow cab for exhaust and 4, 5" passive air intake holes on the bottom of the cab. I know my temps should be about 85, but I can't get them any lower then 93. I've tried different configurations with the fans in terms of blowing or exhausting the air and still 93 is the lowest I can get it.

The four fans on top are rated at 54cfm's each for 216cfm. and the four exhausting from my light hood are rated at 68.54 each for 274.16 cfm, so in theory I'm moving 490.16 cfm. So why is my room so hot? Any ideas how I can lower my temps?

Thanks.

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post better pics up so we can help better. the pics you have are pics of pc fans. i cant really tell what u got going on in there. like i said in my earlier post. the pc fans are weak.they are barelly pushing air.exspecially if you have all of them wired on the same adapter.i doubt your getting 490cfm.you would not be having heat problems.

how about getting a portable fan in there to push around the air.

dude stay away from PC fans. thos things seriously lack umph

Picture update, it's still to hot. Any ideas? If I did get a inline fan would it best to exhaust the light or room? Thanks.

I told you what you need to do. I am a big proponent of PC fans but in your case they simply wont work. All they are doing is moving air around. You need to find a way to move that heat out of your closet and away from all your gear. Highend computer stores and the internet sell ducting specifically for those fans but I would just spend the extra $$ and buy proper ventilation.

Ah hah, You have a metal and wood box, that conducts heat. If I am correct in looking at your setup, you need to cut holes on the top of your box and out the PC fans on the top f the box. Blow the hot air out of the grow room. Also, from the pics the bottom looks like its stagnant air. Drill hols on the bottom sides of the box to let air come in.

Those fans are maybe moving half the volume they indicate. Replace with a single blower from Active Air (or some other supplier), I use a 180cfm in my veg chamber which is 2x4x4 feet. You may consider reducing the light - 1600 watts in the size space is a little overkill. Switching to an air cooled reflector would help as well. In your size grow a single 175 HPS would produce great buds and could be air cooled...Heat is always the enemy.
One final alternative is adding CO2, the plants can stand much more heat when metabolizing large amounts of CO2.

Here you all go a 250 CFM Axial fan that is real quiet for $66 and you go down to Home Depot and get two parts to make it fit in your grow tent. You will need (1) 6 inch to 4 inch Duct reducer and (1) 6 inch duct spacer. Rig and screw the spacer and reducer together and screw in the fan to the spacer. So for $75 you get a 250 CFM axial fan and save yourselves $$$$$$$$$$$$$$$$$$$$$$$$$. http://www.customavrack.com/Products/789-middle-atlantic-fan-6-ac-rack-fan-6-inch.aspx

Ok so for a couple of days I've been trying different fan configurations. I even tried using the fan's for the intake instead of the exhaust, with no change. That's when it occurred to me I'm leaving the thermometer right under the lights about 2''. I then moved the thermometer around the box; on the bottom, on top of the light box, and my temps came up mid 80's. Perfect, right? Where should I be placing the thermometer, for the temp reading? I was putting it right under the light where the plant would be and that's when I was coming up with high 90's. But the reading's I'm getting around the cabinet is mid 80's. So I guess my question is which temps do I use to judge the success of the build. I want the cabinet as close to perfect as I can get before I actually start growing, so I don't have to do construction while the plant's are in there. This might sound kind of dumb, but I've never done anything close to this. But hay I'm tired of paying for something that's a simple plant. Thanks.

if ur canopy is 2" away from the lights then ur thermometer needs to be 2" from the light.you should seriouslly think about ditching the pc fans, they suck.

That's what I thought, the worst thing is the amount I spent on the pc fan's is the same as a 4" inline fan. I guess you live and learn. Right now I'm getting 90 at the canopy level, and temperatures in this region are going to be dropping 5-10 degrees in the next few weeks. I'm thinking just starting the way it is, cause where it is, is right next to an outside wall, so I know that closet will drop a few degrees soon. Maybe do that get a crop or two under my belt and come next summer when warmer temps hit spring for an inline. Again thanks for all the advice and answers.

High on the moon said:

That's what I thought, the worst thing is the amount I spent on the pc fan's is the same as a 4" inline fan. I guess you live and learn. Right now I'm getting 90 at the canopy level, and temperatures in this region are going to be dropping 5-10 degrees in the next few weeks. I'm thinking just starting the way it is, cause where it is, is right next to an outside wall, so I know that closet will drop a few degrees soon. Maybe do that get a crop or two under my belt and come next summer when warmer temps hit spring for an inline. Again thanks for all the advice and answers.

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Im in the same postition. Probably be getting an inline next spring as well.

i think mayb your trapping to much heat under that big ass box reflector. take the pc fans off of the box and put them to blow on the canopy area like the other fan you got there.that reflector is just too big imo.