Heating appliances are designed to operate with a consistent draft. Chimney configurations, mechanical draft fans and weather can cause draft fluctuations. These fluctuations result in inefficient combustion and more frequent service calls. Draft controls regulate the airflow through a chimney or vent. By diluting the chimney/vent draft with varying amounts of room air they maintain the draft at a heater's flue outlet within a consistent, safe and efficient range. This single acting control is made of galvanized steel for low maintenance and corrosion resistance. It has integral anchor points and self- aligning, self-centering rocker bearings for long lasting service. A cushioned stop minimizes rattle and noise. Adjustment is easily accomplished by moving counter weight on outside tab.