After countless hours of research between 2005 and 2007 on hand fired wood and coal multi-fuel furnaces at the library, on the internet, and visiting the numerous wood and coal dealers in many different states, I decided to purchase a U.S. Stove Clayton 1600 furnace. The summer of 2007 I had installed a Clayton 1600 furnace in series downstream from my conventional gas forced air furnace. the very valuable tool book I used to size the furnaces new duct work is "The Homeowners Guide to Coalburning Stoves and Furnaces by James W. Morrison." Another useful book in my decision making on what to buy and how to install it is "Solid-Fuel Furnaces and Boilers by John W. Bartok, Jr." Armed with my new set up, I was anxiously awaiting winter. I gently broke in my new Clayton and to my surprise, my new set up far exceeded anyones expectations! It sure blew away the Brunco 190 furnace I had removed. I was marveled by the Claytons efficiency and heat output. The previous two years, with the Brunco 190 furnace, I went through 8 tons of coal and almost 10 cords of wood each winter. I couldn't get the 3700 sq.ft. house above 64 degrees when it was 10 degrees outside, without any gas assistance. The new Clayton set up amazed me. This past year, with the Clayton, I used 6 tons of coal and 3 cords of wood. when it was 10 degrees outside, I could keep the house at 72 degrees easily and up to 77 degrees if I had the ash door draft spinner open all the way. And that was without any gas assistance! So, I'm very pleased with my Clayton 1600 furnace and would highly recommend it! I am convinced it would preform even better in a slightly smaller or better insulated home.