old Furnace/AC fan as an exhaust fan?

Hello all!!!

Recently I had a friend redo his furnaces and he asked me to take them to the dump. I got looking at them ....there is a big fan in them. I pulled it out and found out through some research that its rated for 1200 cfm. My room is 20x15x8...2400 sq ft. So, in a perfect world every two minutes all the air should removed or exchanged.

My room is such that there is a small loft above it. What I am thinking of doing is mounting some duct through the ceiling and into the loft where there will be a charcoal canister. How big of a canister will I need? Do I get one large one or a couple smaller filters? Should I mount the fan to the ceiling and push to loft or should I mount it in the loft and pull air up and then into the canisters.

All help appreciated!!!!!

That's 2400 CUBIC FEET not square feet homie. It's more than enough.

Edit: That is to say you aim at exhausting all the air in your room every 2 minutes.

Personal opinion, do it if you're trying to save money buying fans. Otherwise throw in a pair of 10-12" inline fans and you'll be sitting pretty.

It has 4 speeds to go through so I should be able to dial it in. I don't want to create a qind tunnel...this was just free and hopefully powerful enough.

Yes cu. ft. Good catch.

MOAB420 said:

It has 4 speeds to go through so I should be able to dial it in. I don't want to create a qind tunnel...this was just free and hopefully powerful enough.

Yes cu. ft. Good catch.

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You won't build up a wind tunnel if you don't have an intake fan running at the same time on the opposite side of the grow room. If you only have an exhaust fan running when lights are off, like I'm doing, you'll only build up negative pressure. Your plants will hardly move at all.