What type of draft system utilizes atmospheric conditions for air induction?

A natural draft system relies on atmospheric conditions to induce airflow through a chimney or stack. This system takes advantage of the principles of buoyancy and temperature differences between the hot gases produced by combustion and the cooler outside air. As the hot air rises, it creates a negative pressure at the bottom, drawing fresh air in. This type of draft is typically used in processes where the setup is designed to work with passive airflow, like in many residential heating systems and traditional boilers.

Induced draft and forced draft systems, on the other hand, actively use fans or blowers to control the airflow. Induced draft fans pull flue gases out of the combustion chamber and into the atmosphere but do so mechanically, not relying on outside atmospheric conditions. Forced draft systems push air into the combustion area using fans, enhancing combustion efficiency but also relying on mechanical means rather than natural convection currents. Mechanical draft systems encompass both induced and forced draft methods, emphasizing the use of equipment to manage air and gas movement.

In contrast, natural draft systems are distinct in their reliance on natural atmospheric conditions without dependence on mechanical mechanisms, making them effective and cost-efficient in certain applications.