50,000 BTU Forsaire Counterflow Top-Vent Natural Gas Wall HeaterWilliams' Forsaire is equipped with a counterflow blower system that receives air at ceiling level, warms it and quietly delivers it at floor level. They may be recessed into the stud space or surface mounted and vented vertically through the ceiling and roof. Ideal for homes, apartments, offices, schools, cabins and many other applications. High efficient 76% AFUE heats approximately 850 sq. ft. Standing pilot ignition helps ensure a fast start time