Which of the following indicates a need for maintenance in an oil burner?

Unusual sounds during operation are a strong indicator that maintenance is necessary for an oil burner. When an oil burner operates correctly, it should run smoothly and quietly. Any abnormal noises—such as banging, popping, or excessive hissing—typically suggest that there may be mechanical issues that need to be addressed. These could be due to factors like improper combustion, mechanical wear, or blockages in the burner system. Identifying and rectifying these issues through maintenance can prevent further damage and ensure optimal performance of the oil burner.

Other indicators, such as consistent burn quality and a stable fuel supply, generally reflect healthy operational conditions, while frequent servicing typically implies a routine check without specific issues. Therefore, while consistent performance is ideal, unusual sounds directly signal that a closer inspection is needed to maintain safety and efficiency.