What is the purpose of the burner assembly in a boiler?

The burner assembly in a boiler serves the essential purpose of mixing fuel with air to achieve combustion. This process is critical for generating the heat required to convert water into steam in the boiler. By ensuring a proper mix of fuel and air, the burner can facilitate efficient combustion, which maximizes energy output and minimizes emissions.

In a well-designed burner assembly, features like air registers and fuel nozzles are used to provide the necessary conditions for combustion. The right fuel-to-air ratio is crucial; if the mixture is too rich or too lean, it can result in incomplete combustion, leading to increased emissions and reduced efficiency.

The other options, although they pertain to boiler operations, do not directly describe the function of the burner assembly. The control of water levels is managed through other components such as level sensors and controls. Filtering steam is handled by steam separators or purifiers, while cooling down the boiler is an operation typically associated with safety measures or maintenance, not related to the burner assembly's core function.