Ventilation Question : Air Intake Size

Hey guys,

I am about ready to cut my air intakes....The space up top is where the fan will be sitting (along with electrical)....The fan intake will actually be facing the ceiling of the top compartment..here is a pic of someone who has it setup like this. That wood thing you see around the fan holds the carbon, and is where the fan intake is. (My cab has more space above the fan than this set up - I'd say about 2" or so)



link to above fan if anyone is interested - https://www.icmag.com/ic/showthread.php?t=45196

The two chambers on the left are for veggin', cloning, etc......The chamber on the right is for flowering.....

The fan is a Panasonic whisper bathroom fan - 80 cfm with a 4" duct. Total cubic feet for the cabinet is roughly 40cf.

I was planning on cutting a hole on top of the flower chamber and putting pvc pipe in there.....Then I will cut a hole in the floor of the flower chamber and put PVC in that hole.

Then I was going to cut a hole in the top of the top veggin' chamber (add PVC too).....And for now I am just going to cut a hole in the divider between the two veggin' chambers, and from there I will cut a hole in the floor of the bottom veggin' chamber (add PVC here too).

QUESTIONS:

I was thinking of going with something like 2" pvc....Is this ok ? If it is, do I have enough intake with the two floor intakes ? Or do I need to drill out more floor intakes ?

If, not 2" PVC should I go with something bigger here ?

here's a pic of the cab so far:

Why add the pvc at all? You want your fan to suck air out from the top if your aim is to make a sort of heat dispersion smoke stack that makes sense but you want a 4 inch pvc isn't your fan 4 inches?! You can use rtv silicone to bind the fan to the top of the pvc...Idk maybe i'm not getting it...for intake your aim is to allow enough air in that your fan is barely fighting the pressure in the room, you want negative pressure but you don't want to burn your fan out fast, whatever size space you evacuate from is the size intake you should have at minimum. Since you're fan is pretty small that should suffice in this case

Maybe I'm just high but I'm having a hard time deciphering kermit's post...

I guess to put it in a nut shell.....

The exhaust is taken care of.....going to be a 4" duct out the back.

The top room is going to be sealed off except for whatever air holes I make.....

So,what size and how many holes should I drill in the top dividing shelf, the mid veggin' dividing shelf, and the floor ?

You should exhaust out the top for proper heat dispersion and to avoid pulling out the co2 which is what will happen if you put the fan too low out the back..if your putting it right at the top in the back the only worry is will you have enough clearance behind the cab to allow the fan to blow the air..so the holes your asking about are to join the sections basically? Is the hole in the floor you are going to cut for the intake? You want A small intake on both sides instead of one large one then your holes through the levels to join their environment need to be again at least the size of the air being pulled through so 2 inches each should be just right