What is not a type of automatic combustion control system?

The option "Regulating" is not typically classified as a type of automatic combustion control system. Automatic combustion control systems are designed to manage and optimize the combustion process to ensure efficiency and safety.

Feedback control uses information from the combustion process to make real-time adjustments, allowing for dynamic control based on changes in operational conditions. Proportional control adjusts the output in proportion to the difference between a desired setpoint and the actual process variable, providing a balanced control response. On-off control simply toggles the combustion system on or off based on whether the desired temperature or pressure is exceeded, making it a straightforward method of maintaining levels but not necessarily fine-tuning the combustion process.

Regulating, on the other hand, is generally a broader term that describes the act of maintaining certain operational parameters but does not specifically refer to a recognized type of automatic combustion control system. Thus, it stands out as the option that does not fit the classification of the other more defined control methods.