CFM and Can Fan Questions

[mellowmama]

Noob here. I have searched this and other forums, plus the internet in general, and still can't decide. I am interested in a Panasonic Whisperline In-Line Fan, thanks to a recommendation from another forum member. I am having trouble deciding between the 240 cfm and the 340 cfm. Price difference is just $5 on Amazon.

The most informative article I found on calculating needed cfm said:

8' x 8.5' x 7' = 476
exchange every 3 minutes = 476/3 = 159

add 5% per air-cooled light (1)
add 5% for co2 (maybe later)
add 20% for carbon filter
5 + 5 + 20 = 30%

159 x 1.30% = 206

By this calculation the 240 cfm should be sufficient. I will be venting this size room, but the room itself is not a true grow room; instead a turnkey 2 x 3 6 closet will be in the closed room, with the closet venting through an Odorsok and cooling a 600 watt hps. Just being extra cautious. I can't tell yet how severe the bends in the ductwork will be, but there will be some.

So, 240 or 340? Is there a negative to choosing too high on cfm?

Also, about can filters... I assume one chooses a model where the maximum cfm is close to the same cfm as the fan?

Anyone have any preferences for brands of can filters? Anyone have any experience with the Can-Lite?

Thanks for any and all help!

mellow

 

[DEAN420]

more the better, for when the hot months come

And as you said you'll have bends in the ducting and your filter will reduce a lil bit of power also

 

[dragontoker]

By your calculations a 240 cfm should be sufficient but border line being that you didnt factor length of pipe run or bends. I would go for the 340cfm fan.

Negatives of a higher cfm fan are only going to be noise and more electricity use (57watts compared to 98w). The 340 will be a little louder then the 240.

Go with the 340 and oversize the shit out of the filter, which equals less load on the fan.

I bought the 240cfm fan and a ( hydroponics 6 Inlet / Outlet carbon active de-odor Filter ) 650cfm filter. The filter manufacture I believe over rated the filter cfm because it loads down the fan quite a bit.

Your drawing on other post showed the filter on the outside of the room. Its going to have to be inside the gun room. The filter has an outlet connection only.

 

[mellowmama]

Thanks a bunch.

Puff, I finally realized I would have to put the filter inside the room. Thinking of hanging it horizontally between the floor joists, over the grow closet. Shouldn't be too conspicuous there, plus it gives the ductwork a straight shot to the window.

See the illustration. The ductwork would be approximately 23' in length, if my floorplan is at all accurate.

I show the fan more or less in the middle of the ductwork.

Think this will work?

 

[dragontoker]

Looks good from my house

 

[mellowmama]

Thanks again for all your help!