Need some air flow advice

[n2theclouds]

Hey everyone I am making finally getting a cabinet together and needed some advice. I am just wanting to see everyones ideas on how i should set this box up. I am a good handy man and can make about anything but i am not too good with the designing aspect of it. Here are the dimensions of the box:

Outside: 44" L x 28" H x 24" D
Inside Main: 27 1/8" L x 25 5/8" H x 23 3/4" D
Inside left: 3 3/4" W x 25 5/8" H x 23 3/4" D
Inside Right: 10" W x 25 5/8" H x 23 3/4" D

I was thinking about using the right side for clones and the main room for mothers and veg. I have another cabinet that i am working on building as well that will have a 400W HPS and is quite a bit larger than this one. I is still a bit away from being finished and i came across this one that was already built so i figured i could use it to start up. Oh btw i will be doing this cab with cfls most likely.

How do yall think i should set up my air flow? Do u have any suggestions for anything that i may need to think about?

thanks

 

[FreezerBoy]

I'd start here Ventilation 101 I don't do multi-chambers so, that's the best I can do you.

 

[DiscoBiscuit]

Here's an idea I used on my cab. The sketch is primitive and not to scale but you can get an idea how it works.

The top right drawer area could be utility. The lower two drawer area should be tall enough for clones/mothers.

The black circles are holes cut into the cab for air flow. Intakes for each chamber run cooler than a single intake into veg, then flower. This way, each grow chamber gets ambient air w/o being previously heated by the adjacent chamber lights.

This sketch assumes the cab floor is several inches above the floor it sits on. If you can't get sufficient air flow under the pedestal, locate intake holes on the back panel, as close to the cab floor as possible. Check out my cab thread (page 5, I think) that shows the light trap for the holes in the floor. The traps are boards cut smaller (L x W) than the cab floor with spacers to allow airflow through the holes, between the trap and the cab walls. The trap also acts as a cab floor for your plants. With the trap, pots/reservoir don't block the air holes.

To size the holes, determine the size of the exhaust fan first. You'll want 2x this size for passive intake, divided between the two grow chambers. The flower area will be much hotter than veg so the flower holes will be much bigger than the veg holes. If you plan to use low intensity light for veg, a 75/25 airflow split will work great. If you use high intensity light in veg, the veg airflow will need to be increased.

Example: Let's say you're using a 6" exhaust fan for the cab. The general rule of thumb says you'll need 12 square inches of passive intake. You'll need to configure the 12 square inches to get the 75/25 ratio I mentioned earlier. That's 9 square inches in flower and 3 square inches in veg. Note: A 9 inch diameter hole does not equal 9 sq. in. The area of a circle is Radius squared x 3.14. This formula gives you the square inch equivalent of a round hole.

The holes you cut in the utility panels is the same size as the respective grow chamber. Example: If you're going with the 9 sq. in. hole in flower, the utility wall adjacent to flower needs to be 9 sq. in. also. The hole in the utility floor is the same size as the veg intake.

Since veg lights run a longer cycle than flower, you risk light leaking from veg, through utilty and into flower. The same panel trap design (used in utility) will block this leak. You could put the utility trap on the wall or the floor. If utility it too cramped, put the trap on the veg ceiling. This chit works great but I'm not the best at explaining what I conceive. If you're interested, I'll be happy to answer questions.

That's a great box for a cab. I can't wait to see it full of green. Peace, DB

EDIT: I just saw the small area left of flower. This could be a harvest dryer. You can even vent it through the scrubber for total odor control if you want.

 

[n2theclouds]

Thanks DB i never would have thought to do it that way. And the idea for the drying room is great too. Do u think it would be ok to use the black pvc elbows as a light trap? I do have like 3-4 in clearance under the cab so i should be able to draw air from underneath.

Also thanks for the link Freezerboy. I started to look through it and it kindof makes my head hurt I think I will sift through that when I'm not under the influence haha.

 

[FreezerBoy]

I started to look through it and it kindof makes my head hurt

Me too. Don't feel bad. Think of it as cauterizing a gaping chest wound. Hurts like hell but, it's good for you.

 

[DiscoBiscuit]

Do u think it would be ok to use the black pvc elbows as a light trap? I do have like 3-4 in clearance under the cab so i should be able to draw air from underneath.

Yep, that will work.

 

[n2theclouds]

ok so ive worked up some numbers. can yall let me know if this looks good? So on the left side I am going to put four 3.5'' intake holes and on the right i will have two of them. The total intake area i need for my 6'' exhaust fan is 56.6 and the total area for my configuration is 57.6. Is that in the green so to speak. Im not sure how to take into account my scrubber so thats really the only thing im not sure about.

thanks