So I have 2 fireplaces... one on top of the other... 3 flues. 2 for each fireplace, and one for my oil furnace... my basement is large, open, and semi finished, but not insulated from what I can tell. the top 2' of the basement is exposed.. however the brickwork, goes atlest 1' below ground... (brick house) so the cinderblock walls are insulated with brick for the 2' that basement extends above ground level... if that makes sense... on the inside, its 1x6's for 3', to a ledge then bring on the inside, with a 2" gap... so standing in the basement, one wall is solid brick with a 2" gap to the block.. the over 3 walls is 1x6's 3" long, a ledge, like a fireplace mantel, and then below that is more brick.. aside from that there is no insulation in the basement. but theres a fireplace next to the furnace about 3' away. I could put the pellet stove there, and then tie it into the existing ductwork... However fire codes may have a serious say in this... thoughts?