The vendor who sold me my stoker recommended that the barometric damp be at the very bottom of the pipe, where the pipe comes out of the stove.
So the gas would come out the pipe far enough to get by the coal hopper, then a T that would turn the gasses upward, with the damper on the end.
Seems like a good idea, as it would make it easy to clean out fly ash, and keep the pipe cooler.
But the diagram for the damper has arrows pointing at elbows, saying Not Here. I am thinking that the Not Here may be more for wood or oil fired installations, where there are sudden changes in gas pressure.
Anyone have an opinion on if the damper should be installed at the very bottom, using a T instead of an elbow