This is my findings, in my environment.
400w with hood. Hood as shown with straight ducting leading to nowhere. I found when set up like this, the heat build up inside hood, generally flowed outside without needing to exhaust. I do have a 150mm axial fan inline with the ducting however.
I have a carbon filter (hiding top left corner) connected to a 150mm centrifugal fan controlled via a variac. The variac at the moment is set to 60v, as it is middle of winter here, reports of snow tonight in a place that where normally a slight frost is uncommon!
From carbon filter directly up and out of tent to the centrifugal fan buried deep in the 44 gallon drum, surround by silencer batts. I still think, this is where you need to spend the money, exhaust fan and control. A cheap 150mm axial fan for the hood will do.
Both centrifugal and axial fan are connected to
1 of these digital thermostats that control flowering, mother, clone. The two dimmer controllers are for teh hood axial fan and the exhaust for flowering room. Variac for centrifugal main exhaust.
I was amazed how much heat moved from hood and out the duct without the fan going, natural flow. From now until mid summer, the ambient temperature is only going to rise, last summer I survived, few tweeks here and there, and I think summer for me this time around won't be too bad.
If you are mid summer now, you're temperatures are only going to start dropping.
I'm going to be using a 400 watt air cooled hood in a 5x4x8, and I'm trying to nail down what I want to do with ventilation. Saw this picture in a different thread they said the #2 fan wasn't necessary as passive intake would be enough. Is this true? I'm going to use a 6" hydrofarm inline and I'll have a regular fan in there too. How's that sound to you? Also, the exhaust opening should be 2x the intake size right? Thanks.
