What primarily controls mechanical draft in a boiler?

Mechanical draft in a boiler is primarily controlled by the speed of the fan and the position of the damper. The fan is responsible for either blowing air into the combustion chamber or pulling flue gases out, thereby creating the necessary draft for effective combustion. The speed at which the fan operates directly influences the amount of air drawn into the system, affecting the efficiency of combustion and the overall performance of the boiler.

Additionally, the damper adjusts the airflow by opening or closing to modify resistance in the system. Proper positioning of the damper ensures that the right amount of air is mixed with the fuel for optimal combustion. Together, the fan speed and damper position allow for precise control of the draft, ensuring that the boiler operates safely and efficiently under varying conditions.

Other factors, such as water circulation, temperature settings, and fuel input rate, do influence boiler operation but do not primarily control the mechanical draft directly. These elements may affect combustion efficiency or overall boiler performance, but the fundamental control of mechanical draft is specifically tied to the fan dynamics and damper adjustments.