Dresser Grow - Ventilation Help

Hello there.

I need some help with my dresser grow box. My dresser is 27 x 30 x 13 (Width x Height x Depth).
I have 4 x 12mm, 1 x 10 mm, 3 x 8mm PC Fans. I don't know their power or CFM. The bigger the more air it blows.
I am planning on build a 250w CFL grow, 10 or 8 cfl light bulbs. No ducting because I couldnt figure out how to manage it yet.

I have read that it is not necessary to have intake fans, just exhaust and let the fluid dynamics do its job, but here where I live the temps hits 80+ degrees very often.

This is what I sketch'd for this dresser grow (please don't mind the metric measures):



Two 12mm fans intake at right and two 12mm fans exhaust at left to make sure all air from outside blown to the bulbs are pulled out after travelling a - almost - straight path.
And 3 or 4 intake fans on bottom part blowing fresh air directly on the plants or above them(I am not sure if this is the best option) to provide CO2 and cool the temp.

I need any suggestion, tips or even critics on this sketch. Do you think the top fan scheme will do its job on keeping the temps down? Do you think I should only provide exhaust?
Thank you!

bring new air in the bottom old air out the top. Don't blow air on your plants unless the fan oscillates, air blowing in one spot will damage leaves. What's your plan for odor control? Use fans in and out for best results IME

I did a 2.5' x 2.5' x 4' 400W HPS + over 100W CFL grow in so-cal in the summer on the upper floor of an apartment building with 4x 120mm pc fans (good ones). Temps regularly hit over 85*F, no AC. I don't remember my yield, but it was good... no problems (except I didn't have enough height- I didn't do any training and vegged a week too long). I would put all the fans at the top and have passive intake holes in the bottom.

dirtWeevil said:

bring new air in the bottom old air out the top. Don't blow air on your plants unless the fan oscillates, air blowing in one spot will damage leaves. What's your plan for odor control? Use fans in and out for best results IME

Click to expand...

I am thinking on placing some dyi carbon filters on exhaust fans for odor control.

friedguy said:

I did a 2.5' x 2.5' x 4' 400W HPS + over 100W CFL grow in so-cal in the summer on the upper floor of an apartment building with 4x 120mm pc fans (good ones). Temps regularly hit over 85*F, no AC. I don't remember my yield, but it was good... no problems (except I didn't have enough height- I didn't do any training and vegged a week too long). I would put all the fans at the top and have passive intake holes in the bottom.

Click to expand...

Where did you place your coolers? All four pulling air out?
I am thinking of this too. I think it will be nice along with some intakes at the bottom and a few holes (passive).

I hot glued them all to form a large square. Then I attached them to a the top of a wood box with a hinge (so they open, like a door). I removed the bottom of the box and replaced it with a screen. I then hot glued the box to the top of the cabinet where I cut a large hole. I would open the box (by tilting the fans like a door) and fill it with activated carbon, which I then covered with an old thin piece of cloth (so the fans wouldn't suck up all the carbon). Worked great.

Instead of a few large holes at the bottom, I drilled about 50 small holes all around the bottom of the box.

Worked great. No smell and 4 plants that yielded well.

Cfls can get warm especially more than one, so if your temps are above 80 you'll want a way to vent the air out.

one fan would suffice over 4 fans. Placed on the left side, the outtake fan will pull air to the right. 2 intake holes at the bottom on both sides passively bringing in air would be good to.