Is there a limit on the number of hours the fan should run without cooling?
For fans and EcoPlus Inline Duct Boosters there is no limit on the amount of hours you can run the fan without turning it off. The fan should not overheat from constant use.
How many amps will this fan pull?
The 6" EcoPlus Inline Booster Fan will draw 0.65 Amps of current.
How many watts does the 6" version use?
The 6" EcoPlus Inline Duct Booster uses about 77 watts.
How many watts does the 8'' EcoPlus inline booster use?
Could this form of inline fan be hooked directly to a charcoal filter, and still pull the air through efficiently?
no this product would not work correctly for that type of usage. a duct booster is used primarily used for long ducting runs so that there is an even flower of air from intake to exhaust.
Can you vary the speed of this fan?
Yes, but you must have a Duct Fan "Speedster" Speed Adjuster! http://www.greners.com/duct-fan-speed-adjuster.html