Passive or Active intake? good question here.

[JBonez]

Ok, so inline fans are not cheap! here is what i need to know, also people with passive or active intake experience are welcomed to chime in!

i am building 2 4'x4'x7' grow rooms with a total volume of 112 cubic ft.

now, instead of buying a million can fans, one for intake, lighting, and exhaust, can i get away with a passive intake system and say, one 800 cfm inline fan to pull air through a carbon filter?

heres what im asking

ducting to the exterior-Canfan-ducting-aircooled hood-ducting-carbon filter

intake will be a light secured hole in the growroom that hopefully will have air pulled in by the enormous cfm canfan exhaust. thanks in advance guys!

 

[King Bud]

If you have air being pushed outside from the grow room, then air will be drawn into the grow room.

One thing to keep in mind.. say you are in well-built house, with very few air leaks.. your fan will run slower (than in a house with an open window), because it's not as easy to pull air in.

i am building 2 4'x4'x7' grow rooms with a total volume of 112 cubic ft.

If you have two rooms, that's 224 cf..
You may want the air to completely recirculate every 6 m (rule of thumb)..
224cf/6m = 37.3cfm

As an educated guess, an 800cfm fan, even when running slower due to carbon filter, two aircooled hoods, and passive intake, should be plenty.

Making sure all the exhaust connections are tight will help will cfm loss.

Goodluck

 

[ktownlegend]

you can actually run ducting through numerous lights with only a couple of fans to do ur pushing and pulling of air. if your numbers are right on when it comes to the CFM/space/heat you should be able to calculate like i have and come out with a system that requires very little fan power.

passive most definitly

 

[JBonez]

OK, So check this out then, could i get away with using my 312 cfm can fan to pull air from one side of one grow box, and run it through the other grow box so that it never pulls air from either of the grow boxs, and then use my 500 cfm 8" can fan to pull air from the two tents and then just setup a passive intake on both?