The US Stove Hot Blast 1500 add on furnace is designed to use in conjunction with your existing HVAC ductwork and work seamlessly with your existing furnace. With twin 500 CFM blowers and up to 139,000 BTUs, it is designed to heat a home up to 2,500 Sq. Ft. This coal only unit is made with a firebrick lined plate steel firebox surrounded by black painted steel giving the unit an eye appealing look. Connection to your existing ductwork is easy with the two 8 inch diameter heat outlets. Available accessories include the universal filter box kit (UFB908) and the barometric damper regulator (DR-6). The optional draft inducer kit (model 11DIKL) can be installed to allow the furnace to be thermostatically controlled and gives the option to change the on/off times of the distribution blower(s).