The feature that differentiates a Direct Gas-Fired Heating System from other types of heating equipment is its burner system. A “trough” or “line” burner is installed directly in the supply air stream. Combustion products are introduced into the building space during operation. Buffalo Blower Co. has developed reliable and efficient air make-up units for industrial building ventilation. In industrial plants where there is a high density of employees and many manual operations involved, an improvement in the environment can produce substantial benefits in terms of increased production, reduced errors, and a decline in complaints and absenteeism among employees.