small box, high temps?

[fishboybug]

hey guys, i am trying to cool a very small area and can't seem to get my temps below 80. the temps in my small box range from 81-88 degrees. the room the box is in stays around 74 degrees. i have 2 4" pc fans at the top of my box venting out and an 8" fan at the bottom sucking air in. my box is 2'x2'x4' (16cf). if i were to buy a 6" duct fan with a cfm of around 240, would that pull in enough air to keep my temps lower than what they have been running? i also need to hook a carbon filter to the same fan. i am using 8 26w cfl's for light. thanks

 

[The Hemp Goddess]

When you can, I would shoot for a 250W HPS and build yourself a cool tube. Eight 26W cfls--208W, approx 12800 lumens, 61.5 lumens per watt. A 250W HPS--250W, approx 28500 lumens, 114 lumens per watt (and less heat). You can probably cool a cool tube with the 4" cpu fans you have, as I don't think they are helping you where they are. You could draw air from outside your closet with 1 of the 4" fans, duct to light, duct from light, exhaust with second cpu fan outside of room and you would not need a carbon filter on this.

Use the larger 8" fan for the exhaust. Although I do not know the cfms of the fans you are using (what are they, cfms are important?), it is most likely that the 8" is taking in far more air than the 2 4" cpu fans are capable of exhausting. You may actually be better off using passive intakes and forgetting the cpu fans--they will be useless on a carbon filter and the cross sectional area is far less. An 8" circle is 50.25 sq in and 2 4" circles are 27.2 sq in. The sq inches of your intake and exhaust should be the same.

 

[fishboybug]

thanks hemp. didn't konw in and out had to be the same.

 

[fishboybug]

well i turned the 8" fan around to vent but its venting out of the bottom and the intake is at the top. temps are now holding steady around 80 degrees. i was thinking about making an air scrubber to go on the bottom vent to help with the odor in later stages. do you think having the scrubber in the bottom of the box is a bad thing? will odor still leak out the passive intake at the top?

 

[The Hemp Goddess]

No, you cannot just turn the fan around, you have to move it. You need to exhaust air from the top of your space because that is where the hot air is and pull air from floor level because that is where the cool air is.

 

[fishboybug]

No, you cannot just turn the fan around, you have to move it. You need to exhaust air from the top of your space because that is where the hot air is and pull air from floor level because that is where the cool air is.

i understand the process of heat rising and cold air falling. but my temps today, with the 8" fan venting out the bottom of the box, have not went above 78 degrees. the thermometer is located in the hood just above the lights. if i am maintaining a temp that is 10 degrees cooler why does it still need to be exhausted through the top of the box? is there some sort of physics i'm missing or is venting just the normal rule?