Ventilation Question: Rhizome if your out there...

I am looking to redo my growroom now that I've had a couple grows. Rhizome, I read your thread posted a while back, great stuff. My question is can I ventilate two rooms with the same fan by putting in a "T" in my duct work. If I do this I would come out of the fan with an elbow and go into a "T". Drop one line straight down and then continue into the next room with the remaining trunk. If I do this and use an 8 inch fan can I use a reducer and go from an 8 inch duct into (2) 6 inch ducts or how do I figure the reducer into the equation. Also If I use a passive intake and it is humid outside in the summer is this going to introduce a lot of humidity into my grow area? Vise versa, if it is cold and dry in the winter is my grow area going to get really cold and dry? As far as the grow areas the combined cubic Feet is about 390. I'll have about 20 feet of duct and two carbon filters, (1 in each room). My light is a 400 hps and a 400 mh in one room and a 160 T12 in another room. Anyone have any insight? Thanks.:jointsmile:

Your questions have raised more questions.
Are you sucking air from the room into the carbon filters, then thru duct to fan?
You could put the filter on the exhaust side of the fan.
Why don't you attach the T or the reducer, then the T directly to the fan?(eliminate 1 bend)you should be able to do 2 rooms w/1 fan as long as it is big enough.
Bends reduce air flow, so you will have more draw on the line with less bends.
Also heat rises, so you may want to suck air from higher in the room instead of down low.
Where are you getting your intake air from? With passive or active intake, that ail will be the same temp and humidity as the room it comes from.
Good luck

Yes, will be sucking air from room through air filter, through duct, through fan, through basement window to outside. Intake will be in same window. Can't put filter on outside but I could raise it off the floor and reduce the duct size. Good idea. Intake air will come from outside. Was thinking about winter time and wondering if i wrapped the intake duct with some of that electrical heat tape, would that warm the duct enough to warm the intake air? Usually they use that stuff on outside pipes to keep them from freezing but would it work on an airduct? I have to have an elbow cause the window is in the corner so I have to come off with an elbow so I can service both rooms. The area is literally perfect, High on Rhizome's Value Chart:thumbsup:

An 8" inline is plenty of fan for this application. Watch out for variable air resistance after the tee- You may have to install some dampers to get good flow through the farthest intake.

You'll want an atmospheric/environmental controller to regulate your temp/humidity. You won't be able to regulate the two spaces seperately on a single fan, short of some highend HVAC work. Worry about flower if you're only regulating one.


Don't stress over intake temps- colder air will just cool the room faster. Make sure you have good air movement w/in the rooms to prevent stratification. Pipe heater elements won't do crap for air- contact time is too short.

Do you think I should drop down to a 4 in duct for the smaller room and keep the 6 in duct for the bigger (For Flowering) or put dampers on. the smaller area is going to be for sprouts, clones, maybe a little veg, and hanging and drying. I have very little air exchange now and my plants look pretty good. I'm sure with the system I'm putting in they'll be great, but I really want to control the odor when it peaks up. Thanks Rhizome