Well I did it. I finally found a wood burning furnace to heat my upcoming 30 x 40 pole barn. This forum helped me out in my decision so much. Thank you all! I found a Northwood Heater built by Chippewa Welding on craigslist for $175. It is in excellent condition compared to so many others I've found for sale this cheap. I plan on replacing the fire brick and all the gaskets. Once my building is completed I will find myself researching the chimney construction....I understand it is expensive! Thanks again to everyone on this site....you helped me out and didn't know it....I will post pics soon