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Originally Posted by Hawk  I'm not sure I understand the logic of the intake setup. Your exhaust cfm would be 3x what your intake is supplying (not accounting for ducting losses on either end).
Why not use all your fan power for exhaust and run passive intakes? Conventional wisdom holds that passive intakes should be twice the size of your exhaust. In other words, if the smallest diameter of your exhaust ducting is 6" you'd want (2) 6" passive intakes.
Is the issue that your fresh air intake is limited to 4" for some reason? Even if that's the situation, I wonder if the 101cfm intake fan will just create more of a problem in terms of obstruction than benefit in terms of air flow. Again, maybe it's better to have that 101cfm pulling out of the space as an exhaust and let the two fans just pull in as much air as possible through that 4" as passive intake. You'd be sure to have plenty of negative pressure in the grow space for containing odor that way.
Regarding the general question of too much exhausting: Within reason, I'm not sure it's really possible in terms of plant health. Having more than necessary may cost you in terms of sound and electrical usage but unless the plants are being wipped around by massive airflow I can't see how it would be harmful. I am not an expert, however.
Better to have too much than not enough, I say. |
the logic is that i was loaded when i was writing this..
i want to put in 4 4" intakes...to make in intake of sixteen square inches and an exauhst of twelve square inches..the reason i want to go with 4" intake is to use as little space as possible....if passive would work that would be awesome(save money on fans) but i will be pulling air in from the outdoors about 4-7 feet away(not sure how im going to route ducting yet) i was thinking a fan would help push the fresh air in......