I'm not worried about the fan. It will be a 4" inline fan readily available. My concern is forcing it down to 2" where it meets the PVC. I have found a 4" to 2" reducer but it isn't actually a reducer in the true sense. It is a 4" to 2" PVC bushing and it doesn't reduce - it's an sharp angled reduction (90 degrees). This is going to be a custom job to be sure.

I've refined my rig config a bit:

charcoal scrubber > 4" exhaust duct > Light hood > 4" exhaust duct > inline fan > 4" exhaust duct > damper/draft control > step down to 2" exhaust PVC > Y connector with shared vacuum line > vents outside.

I'm guessing that I will need a speed control unit and that it will be a question of finding the optimal fan speed. Appreciate any help from the board before I go buying components. This is my only hope for external vent.
bigsby Reviewed by bigsby on . Venting Using 2" PVC? My first post here. Love this site. Tons of great info. I've spent the past couple of weeks reading and searching to pick up knowledge. I see a lot of posts here that could be answered with a simple search. I believing in doing homework before asking questions! That said, here is my case. I'm looking for a little help setting up my grow room. Here is what I've got. Basement set up. Good climate control all year round. Ready access to electric and H20. Lockable and away from all utilities Rating: 5