How much chimney pipe needed for a 2 x 5 flat pan with AUF?

[claystroup]

I have my new Mason 2 x 5 flat pan arch/evaporator all ready to boil this season. I will be boiling outside on my driveway apron. My rig is all insulated and firebricked and has a AUF blower installed. The base stack is 4' tall plus I have 2 additional sections of chimney pipe 4' long. All pipe is 8" diameter. My question is should I run 8' or 12' total height of chimney pipe with the AUF? I have made a adjustable cover for the blower fan intake so I can regulate how much air is being blown into the fire chamber.

Thanks,

Clay

[Haynes Forest Products]

Because you have air injection your not relying on natural draft to keep the fire going. With the air control you can adjust your fire as you need as the day progresses so I would make it high enough to keep the sparks and smoke out of your pans, face and up and away.

[Daveg]

Because you have air injection your not relying on natural draft to keep the fire going. With the air control you can adjust your fire as you need as the day progresses so I would make it high enough to keep the sparks and smoke out of your pans, face and up and away.
More's better; go with 12'. You won't regret it. If you're on the apron, and the wind is blowing towards the garage.............!!