What is the purpose of the shut-off valve located near the burner?

The purpose of the shut-off valve located near the burner is to minimize residual oil in the line after shutdown. This is important because, when the burner is turned off, any remaining oil in the fuel line can lead to a number of issues, such as inefficient operation or potential leaks. By closing the shut-off valve, the system effectively prevents this residual oil from remaining in the line, which helps to ensure that the burner starts cleanly and operates efficiently the next time it is activated. This practice also enhances safety by reducing the risk of fuel spills or unwanted emissions during the downtime of the burner.

The other options do not accurately describe the function of the shut-off valve. Increasing flow pressure does not pertain to the shut-off valve's design, as its primary role is not to alter pressure during operation. Reducing noise is also not a function associated with the shut-off valve since noise management is typically related to other elements of the burner system. Regulating temperature is a separate function managed by the burner’s operational controls and not by the shut-off valve.