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Useful Life of a Furnace

Furnaces made with good quality materials and manufacturing processes, installed properly and maintained well, will work efficiently for a long time. Average equipment lifespans are affected by many elements in addition to materials and maintenance, including the proper maintenance of the buildings they are in and operating conditions. Some home components have an expectancy of 100 years or more, but furnaces last only about a quarter of that time if operated in a well-maintained environment.

Average Furnace Lifespan

Modern furnaces last between 15 and 25 years, on average.

According to the National Association of Home Builders in Washington, D.C.'s Study of Life Expectancy of Home Components, a gas furnace lasts 15 to 20 years and an oil furnace lasts 10 years or less on average. Heat pumps last 16 years and boilers last 13 to 21 years. These average lifespans are for normal operating conditions with proper installation and regular maintenance.

Operating Efficiency

The U.S. Department of Energy advises that while furnaces with condensing units are more expensive than those without condensing units, they save money over their 20-year lifespan, especially in colder climates. The U.S. Department of Energy also advises improving the energy efficiency of your home for maximum operating efficiency of your furnace and to extend its useful life. Recommended maintenance for optimal operation and to keep your furnace running longer includes regular inspection of heating vents, pipes and chimneys, regular adjustments to furnace water and air temperature settings, and regular inspection of sealed connections to ducts.

Conditions Affecting Lifespan

Excessive moisture in pipes and ducts connected to furnaces can reduce their useful life. Installing a furnace that is either too large or too small for the size building it is heating can cause operating problems that lead to furnace failure, such as overheated wiring from constant running. Rusty fittings, connections and housings affect operation efficiency, lead to gas and air leaks and affect the lifespan of the unit.

Repair versus Replacement

Furnaces older than 20 years with operating problems can be expensive to repair. The cost of a replacement furnace varies widely, depending on size, brand, energy efficiency discounts and contractors used. A gas furnace can cost as much as $2,000, central heating up to $5,000 and an oil furnace as much as $6,000, before installation. Problems with furnaces that are less than 10 years old are well worth repairing, but older equipment that is nearer to the end of its useful life might be more economical to replace.

About the Author

Heidi Cardenas specializes in human resources, business and personal finance, small-business advice, home and garden and home improvement. Her professional background includes human resources and business administration, technical writing and corporate communications. She has studied horticulture and business administration, and enjoys guest blogging for publications including Herb Companion Magazine, Natural Home Living Magazine, and Mother Earth Living.