US Patent 9316411 HVAC furnace

A heating, ventilation, and/or air conditioning (HVAC) furnace has a flat burner comprising an upstream side and a downstream side, the flat burner being configured to receive an air-fuel mixture therethrough, a first flow path located adjacent the flat burner and downstream relative to the flat burner, the first flow path configured to receive fluid exiting the flat burner, and a plurality of second flow paths located downstream relative to the first flow path, the plurality of second flow paths being configured to receive fluid from the first flow path.