There is some soot produced by your oil fired equipment and this should be cleaned out every few years. When you have work done on your chimney, also have it checked for cracks in the lining, and removal of leaves and other debris. If you burn a wood stove, you should have your chimney cleaned every 2-3 years. Sometimes birds will build nests in the chimney and cause problems by restricting the flow of air away from your furnace. You can reduce this problem by placing a cap on your chimney. They will not restrict the airflow, and will keep leaves, rain, and other types of debris from becoming lodged in your chimney. *Always call for a Cleaning and Tune-up after having your chimney cleaned. Soot and debris is pushed down to the base of the chimney and may cause a blockage.