Trying to get AOF velocities with stack draft is probably not going to happen. In my system, the AOF pressure is 8 inches of H20 across the nozzle. Thats about 0.3psi, and that is what gives the jets the 80 mph velocity that lets it mix well. If you managed to get anywhere near that much suction with your draft, which is really impossible, it would just draw up through the grate since that is a much easier path. So it would act like a normal system with great draft.
John
2x8 Smokylake drop flue with AOF/ AUF
180 taps on sacks
75 on 3/16 tubing with shurflo
Eden Prairie, Minnesota