How long do furnaces last?

Many residential furnaces provide roughly 15 to 20 years of service, but age alone does not determine the next decision. Maintenance history, heat-exchanger condition, repair frequency, parts availability, comfort, efficiency, and installation quality all matter. A younger furnace with unsafe combustion needs attention; an older furnace that runs safely may still be repairable. If replacement is approaching, compare a properly sized installation quote before the first deep freeze. See the furnace repair service page for diagnosis and the replacement cost guide for planning ranges.