US Stove Hotblast Warm Air Wood/Coal Furnace with 550 cfm Blower The Hotblast 1300 Series Furnace works alone or in conjunction with your existing furnace to heat your entire home while drasticallly reducing home heating costs. Heat output is 87,000 BTU's hr. The Capacity is 1,200 square ft. This unit has a 6" flue collar size with (2) 8" Heat outlets. The Dimensions are 40" H x 21" W x 35" L. Firebox Construction of single front - Full 7 gauge with Firebrick Lining. Clearance to Combustibles: Sides- 12"; Front- 48"; Back- 30". The weight is 375 lbs. 550-CFM blower, Automatic bi-metallic thermostat, extra heavy duty cast-iron grates and liners.