The lifespan of a furnace depends on it’s unique features, when it was manufactured, and how well it was maintained. Typically, a furnace will last 15-20 years. With routine maintenance a furnace can last even longer. On the other hand, a neglected furnace may not last beyond its warranty. Oil-fueled furnaces have the longest life expectancy, and gas-fired furnaces have the shortest. Furnaces older than 10 years should be monitored closely since most furnace repairs happen during the last quarter of its lifespan. Factors impacting the longevity of a furnace include ensuring the furnace is the correct size for your home, the unit and ductwork are installed correctly, and performing routine maintenance. Learn about ensuring the longevity of a furnace and costs for replacement.