Seaghost, thanks for taking the time to reply. As long as you can keep your ducting organized and out of the way, yours sounds like the perfect solution. Shit, my office is 75 degrees and it's like 7 in the morning. I actually never thought of a dual system. The sound of two fans doesn't get to you? Is your cab vent fan inline or a squirrel cage (or all-in-one exhaust with activated charcoal)?
Again, thanks.
Always glad to help
Yeah after reading tons of posts on here and some other forums I figured out that if I had the space then a dual system gave me the best benefits. I got my inline fan from Amazon that was a vortex carbon filter fan combo for $150. Its fairly quiet and my cab will be sound proofed for the most part so noise from it will be minimal.
For the cool tube I got a regular 4" inline duct fan that's mounted at the back of the cab pointed up exhausting into the attic. Inline duct fans are fairly inexpensive, about $35 and mounted that way the noise is very minimal. Plus since my cab is inside my walk in closet that helps shield the noise also.
And I discovered that by using this dual system I was able to use much lower CFM fans which helps with electric and noise. Any good 4" inline duct fan will have a high enough cfm to cool up to a 600 watt HPS. Over that you need 6". Also when mounting the fans to the cab I used rubber screw mounts to help with vibration and sound isolation. Also since my setup is for scrog my light never has to move, my bottom cab does the veg, so that greatly simplifies the ducting.
HTH, if you need any more questions answered feel free to ask
Peace out