Kelly Pridgen wrote:Question: How much will the oval shape of flue (instead of circular) affect performance?
Not much, I'll second Max in this. Most of the friction in square and rectangle shapes are from the corners. Yours is still quite good although the fast streaming, hot core of gases isn't round but stretched out a bit. As long as the chimney is straight up, smooth inside and the height is more than 16' I don't see any problems.
Companion Planting Guide by World Permaculture Association