How do you determine the proper duct size for a fan duct?

[mtumbleson]

I guess another question would be how much cfm would I need for a oven this size?

It's foot print is 4x4 and 8 ft tall...

[Popeye]

Yep that helps.. Squirrel Cage wheel can handle a little Static.
216 Cfm @ .0SP should yield about 175 Cfm @ .2ESP
6.5" Pipe or
14 x 3 or
11 x 3.5 or
9 x 4 or
5 x 7 duct should work
hope that helps

[Popeye]

Your oven at 128 cubic', if you had a 100 Cfm fan you'd turn the air over 46.8 times an hour... that's way more than you need. I'd say 15 to 30 air changes would certainly do the job.
IMO

[mtumbleson]

Can I assume that those figures will translate into sguare inches, meaning I can make my duct in a configuration close to the ones you listed?

Also, would it improve if I did away with one bend?

Just trying to understand it a little more.

Thanks.

[Popeye]

Yes it would be pretty close.. That figure is good for 100' of ductwork.. elbow eats up 20'.. A performance chart of the fan you're using would be nice but I think you're safe using those numbers.

[mtumbleson]

Thanks.