draftcontrol

Draft control refers to the management of the draft, the flow of air or flue gases through a system, to achieve stable combustion, efficient heat transfer, and safe venting. In fireplaces and wood- or coal-fired furnaces, draft is created by the buoyancy of hot gases in the chimney. Excess draft can cause increased fuel consumption and heat loss, while insufficient draft leads to poor combustion and smoke backflow. Draft control devices include manually operated dampers, barometric dampers that regulate pressure differences between indoors and the flue, and automatic or powered dampers and fans that adjust draw in response to sensors or control signals.

Control systems may use simple hysteresis or more advanced feedback loops with draft pressure sensors, combustion air control, and sometimes oxygen sensors to maintain a target draft based on operating conditions. Modern installations often employ programmable logic controllers or building management systems to sustain the desired draft when boiler load, venting resistances, or ambient conditions change. In addition to combustion applications, draft control concepts are relevant to ventilation design and industrial processes where consistent airflow is required for safety and efficiency.

Applications span residential heating appliances, industrial furnaces and boilers, and larger power plant settings where stable draft improves efficiency, reduces emissions, and ensures safe venting. Draft control also intersects with HVAC design to minimize unwanted drafts, prevent cold air infiltration, and optimize venting performance. Safety considerations include the risk of backdraft, buildup of combustion byproducts, and the need for proper installation, maintenance, and detectors such as carbon monoxide alarms. See also barometric damper, chimney, and flue.