Hello Everyone! I used a single duct fan exhaust with a passive intake for my last grow, and while it worked, it is considered by all calculations I've found to be woefully inadequate for the size of the space, so I bought some legit horticulture fans from my local grow shop (6" Durabreeze), I'll be using one to replace my current exhaust fan, and the other as an active intake fan. The exhaust fan is pretty easy, just took the old one off, drilled some holes for anchors, mounted and taped on the 6" ducting to the existing vent. Old New Only problem here is that the movement of the duct hose put it directly in front of the light bulb, oh well, sounds like a next grow problem The intake fan presented some challenges, as there's a wall where it needs to go, one that I built to house the 12" x 12" filter. No getting around it, the fan is too big for the hole. Solution? make the hole bigger! Now she fits Mounted to the concrete floor with anchors. Need to put the wall back up, used a clamp to temporarily hold the blocks in place so I coould countersink and screw them in place. Here's all the blocks in place. And the wall's back in place. I'll caulk the gap and fill the screw holes before I put in a filter and use this as a bloom room, the paint will have to wait. I do need to get the door more light tight though. Cheers!
I wouldn't have bothered with the intake fan and kept it for a spare. If you are using a carbon filter with the exhaust fan and they both have the same CFM rating the exhaust fan will pump more air into the room than the exhaust fan can remove due to the restriction of the filter causing higher pressure in the room that will blow the stink out into the rest of the house. Just run the exhaust fan and make sure the intake area is twice the area as the exhaust port to make sure lots of air can be drawn in by the vacuum the exhaust fan creates when it runs. I have a Heat/RH and speed controller on my 6" exhaust fan so it only runs when it's triggered by the controller and only at half the speed so it's quieter tho noise really isn't an issue for me. My cheapo fan is dying so you can just send me your spare as you won't really need it.
Thanks for the input, fellas, the reason I went with a fan is that the amount of wall space where I can put vents is tiny, and aside from moving the filter wall (a weekend of demo and construction at least (but probably what I'll eventually do)), the only way to get the intake air I need is to use a fan. But yeah, I am thinking about moving that wall in a LOT, since only an oscillating fan lives there, and that I could move to the other side where the filter now resides, turn the wall into a huge filter wall, and have a bunch of air vents on the wall going into the other room, but that also adds an element of noise, since right now it's going through 4 feet of sound insulated ducting so you can barely hear it, if I build a vent wall and a filter wall to allow for adequate intake, or make the bottom 3 stairs big open vents, it'll be way too loud, so until I can figure that one out, this seems the best solution.