I put 3 square bars across my burner, below, and drip pans on top:
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Then, I laid 3 aluminium pans on the bars, the center one on top of the other two:
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And the smoke just drifted up and out the top back smokehouse vent, coming in on the bottom front vent.
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Front bottom vent:
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That's all it is, the smoke works itself around the drip pans to fill the smokehouse with lovely smoke!
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And, I get the aluminum pans at the Dollar Tree, they're cheap and just toss them out the next day after they cool.