Im looking for advice on furnace stove build for our farm shop. The building is 50x100x16 R-19 on walls and aprox R30 in ceiling located in central Maryland. I have welding and fabrication experience and a stack of 1/2" and 5/16" plate thinking large fire box with heavy wall pipe above in fire box as heat exchanger with old furnace fan blowing throughthe pipes many guys around here use double barrel stoves want to build one nice stove that will last me the rest of my days any advice is much appreciated. I already have a 8" chimney in place with old baker stove that dont cut the mustard.