You should have your heating system serviced once a year for a seasonal check-up in the fall. A heating system that is not maintained is a problem waiting to happen. At the very least, you will have escalating operating costs due to the inefficient running of your system and the eventual need for repairs. In the worst case, improperly maintained equipment powered by natural gas can compromise your safety by causing high levels of CO, resulting in serious injury or even death.
There are some maintenance tasks that homeowners can do themselves, such as cleaning and replacing filters. However, in order to insure safe and efficient operation of a heating system, homeowners should have their furnace inspected and cleaned annually by a qualified service technician. The benefit to homeowners, your health and safety, your money and your time, far out way any costs incurred with a yearly inspection.