Manging temperature in a 4x4x8 box

Hi all.

I have a 4w x 4h x 8L box and i am having a hard time getting my temperatures down to the high 70's.

Running 2 x 400HPS

They were over 100f and I have installed a 375CFM fan with a carbon sock and the temps are now running about 85f.

There are 4 small 4" fans inside the box and two 4"x6" opening cut into the bottom as passive intake.

I have had to keep the doors of the box open in order to try and kep the temps down.


If my doors are open, does this mean that the fan is not running the way it should and if the doors are closed i will get better air circulation thus decreasing my temps?

Is the size of the fan adequate at 375CFM for a box this size?

What else can I do to lower the tepms?

Thanks in advance as always.

Is it a homebox type tent?
Put it in a room with an a/c, crank the temps down!
And run your lights with air-cooled hoods, and exhaust them elsewhere- like out a window.

Your fan should be able to maintain the temperatures in normal conditions if installed correctly. You are not saying what size of hole or pipe you are using for your exhaust. Your exhaust should be at the top of your box, preferably right smack between your lights. You are also not saying what the ambient temperature is outside of your box where you are drawing the air from. You will have a temperature difference with your 800 watts of 10 to 15 degrees higher than the temperature is from air being drawn in. 800W produce 2500 btu's of heat and there is no way you will ever get the temperature in your box the same as the ambient air outside just using a fan.
Good Luck
SpaceNeedle


If my doors are open, does this mean that the fan is not running the way it should and if the doors are closed i will get better air circulation thus decreasing my temps?

Is the size of the fan adequate at 375CFM for a box this size?

What else can I do to lower the tepms?

Thanks in advance as always.[/QUOTE]

makes sense..

The fan is 6". I read some of your posts and followed directions such as as few 90's as possible, straight lines and all is in 6" except where it exits the facility, which is an 8" piece of dryer hose.

Ambient temps are 73F.
The fan sucks out of the top on the back wall centered between the lights.
The intake "holes" are on the back wall as well and get air from an 18" space between the box and an exterior cinder block wall.

There is an available a/c duct within 24 inches of the front wall of the box at the top. Could I cut an intake off this duct?
If so is it as easy as cutting the hole and installing a straight piece of 4" duct?

Thanks for the assistance. I value your opinon.

If the air you are drawing in is 73F, you're probably not going to do much better than having the temp in your box at 85F. Using your A/c would help if you tapped into it. If decide to do that, just cut a 6" round hole into it, and see how much air will come out for your to use. If its in the middle of a large duct, and you find you want to get more air out, then you'll have to make an adjustable damper and place it just past the hole you cut in. Here's what they look like, and you can make one yourself --
BROAN MFG CO INC (NAUTILUS) BP87 DUCT DAMPER
It's basically just a piece of metal to re-direct air where you want it, so instead of Remember though, it only works when your thermostat is calling for more cool air where your thermostat is located and doesn't care what the temp is inside your box. So it will only blow cold air when the house is needing a/c not necessairly when your box wants it.

My opinion, it's not worth the hassle as long as your temps don't go over 85.

Thanks spaceneedle.
I'll go with not worth the hassle.