I have a straight 25 foot rectangular duct that is 0.9 sqft in cross-sectional area (11" by 12"). There are openings on either end, and nowhere in the middle. I wish to move about 1000 CFM through the duct.
My plan is to use "duct booster fans" to do all the air movement. I can get a 10" diameter 650 CFM fan, and a 12" diameter 800 CFM fan (which is slightly larger than the duct). Here are some options I'm considering:
- buy two 650 CFM fans, and install them in series: one where the air goes in, one where the air goes out. So the fans will be about 25 feet apart. Will their throughput add to about 1300 CFM? I suspect the answer is no, because nothing good ever adds linearly. But would I get close to 1000CFM?
- buy two 650 CFM fans, and install them in parallel at one end of the duct. This would require either widening the duct or somehow splitting it into two ducts, as two 650 CFM fans side-by-side will not fit in the duct. My intuition is that this would be worse than putting the fans in series, but maybe not?
- buy one 650 CFM fan and one 800 CFM fan, and install the 650 blowing into the duct and the 800 sucking out of the duct (or maybe the other way around?). Because the 800 CFM fan won't fit in the duct, I would have to build a larger frame for it, then connect it with some sort of funnel to the duct.
- same as above, only with two 800 CFM fans.
Any advice would be greatly appreciated.