What type of controller is the airflow controller in reference to automatic boiler controls?

The airflow controller in reference to automatic boiler controls is a proportional-plus-reset controller. This type of controller is designed to maintain a desired setpoint and adjust the airflow in proportion to the error between the setpoint and the actual value.

Proportional-plus-reset control works by providing a proportional response based on the error, which is the difference between the desired temperature and the actual temperature, while also incorporating an integral (reset) action that adjusts for any steady-state error over time. This means that, if there is a persistent discrepancy, the reset action will gradually correct this over time, leading to enhanced stability and accuracy in controlling the airflow.

This approach is essential in boiler applications to ensure efficient combustion and optimal performance. The proportional control aspect allows for real-time adjustments to prevent excessive oscillations, while the reset aspect helps eliminate any remaining steady-state errors. Therefore, this makes the proportional-plus-reset controller particularly suitable for maintaining consistent airflow in automatic boiler systems.