Indoor Gardening Exhaust Fan Options
What are the differences in exhaust fans and which ones can be used in grow tents?
Inline Duct Booster Fans
The inline duct booster fans are too weak to move any real heat issue out of a tent. These are made to help a bigger fan with a long length of ducting. There may be some applications where they can be used in other ways for minimal air movement.
The axial fans are a little better, but only if you don't really have a heat issue, or if the area you're trying to exhaust air from is really small. One axial fan will work OK as an exhaust, but if you add another axial fan for an intake somewhere else, together they'll work pretty good, but again- I wouldn't count on them for a real heat problem, or to move air through a reflector or ducting unless it's a small application.
Squirrel Cage Fans
The squirrel cage fans are the 'old fashioned' way to move air before the centrifugal fans came out. If you mount them "free-flowing" so they don't have any restriction (like carbon filters, reflectors, or any length of ducting) they work OK. They are inexpensive, and they do have some good applications.
The centrifugal type fans are the best approach to most exhaust needs. They always have enough torque to move air with only one fan unless you've got multiple ducted lights. These are also powerful enough to draw air through a respectable length of ducting, or though a reflector, or exhaust hot air completely into another room in your house. We've got a bunch of different brands of centrifugal fans to choose from, but they're all good fans. The Windtunnel's are the quietest of our fans, the EcoPlus fans are powerful and cheap, the CAN's and Vortex fans are the best quality of our fans and have the longest warranties.
CAN Max Fans
The CAN Max fans are a new exclusive breed of exhaust fan. They use less electricity, they are the quietest fans on the market, and they are very powerful. These are top of the line in exhaust.
AIR FLOW is important!
Remember, that in every exhaust application, you have to have an unrestricted intake somewhere in the enclosure. If you run an exhaust fan without another fan for intake (not always necessary), or without a passive intake (a hole) somewhere in the room, you may run into heat issues. Any exhaust fan is going to need an intake in order to work to it's best ability. A rule of thumb is that if you have one 6" exhaust fan, you should have the equivalent of 2- 6" holes for passive intake somewhere else in the enclosure or room.