he does act like an ass when people disagree, but in this situation, he's also correct. For EVERY situation, a passive intake is the CORRECT way do ventilate. Ok maybe if you had flow meters on your ducts linked to. Computer which controlled fan speed, yada yada.... But again, this , um, "de efficient izes" the room.
Scenario one : 300 cubic foot room, one 200 cfm blower exhaust, one 100 cfm blower intake. Generaly this means a 6" exhaust and a 4" intake. Obviously this creates a restricion on the 6" end fromthe 4" end. Even if both are 6", this means the exhaust fan must suck air around two sets of fan blades, it's own, and the intake. This is helped by the push of the intake fan.
Scenario two : sake room, 200 cfm 6" exhaust, 12" passive intake. Because the intake is much larger than the exhaust, no restriction is put upon the exhaust fan and it can effectively move it's rated cfm. This uses less power and cost less initialy than scenario one due not using 100 cfm fan.
Scenario three : same room, both fans on seperate exhaust holes, 12" passive intake. Similar to scnario two, with roughly 50% additional flow through.
It is easy to see which system is the inefficient one. Why you would choose to do anything less than efficient is beyond me. And the facts are, putting a smaller diameter fan on intake than exhaust places a restriction on exhaust which limits efficiency, and using a larger or same sized intake makes maintaining negative pressure in the room a chore which could lead to odor leaks.
To the poster who said they need an intake because of all the leaks : build a better growroom. Air leaks are a prime source of pathogen entry. And light won't bend corners, but it can leak in or out of those "leaks".
What's the problem now?
