Sep 8, 2022

How Long Does a Furnace Last

A furnace is one of the essential features of a home, so knowing about furnace life expectancy is critical for homeowners. How long a furnace will last depends on various factors, including its unique features, when it was manufactured, and how well it has been looked after. For someone living in an older home, the furnace is likely at the end of its lifespan if it has not been replaced within the last few years. Knowing how to spot poor installation or neglectful maintenance can give homeowners a good idea of whether their furnace has time left or is time to replace it.

A well-maintained furnace will last for 15 to 20 years.

Our friends at Carrier tell us that a homeowner can expect a furnace to last 15 to 20 years. With excellent routine maintenance, a furnace can last even longer. Likewise, a neglected furnace may not last beyond its warranty.

A furnace older than ten years should get careful attention since most repairs happen during the last quarter of its lifespan. If a homeowner is unsure of the furnace’s age, they can reference the furnace’s manual to find its serial number. The digits represented when the furnace was manufactured. The furnace should have a label with its model and serial number if a manual is unavailable. You can find this either outside the unit or inside its door or cabinet.

The Right Size Furnace For Your Home Will Ensure A Maximum Lifespan

Selecting the right size furnace is not just choosing a smaller unit that saves money or a larger unit that heats quickly. The right size furnace is about efficiency, determined from the total square footage of a home and the heat output needed for temperature change. Not all homes with the same square footage need the same heat output. Climate, property vegetation, and characteristics of home construction all affect how hard a furnace needs to work.

A unit that is too small will overwork, running continuously to maintain an adequate heat level. This prematurely ages a furnace, lowers its longevity, and increases energy costs. A unit that is too large won’t run continuously but will cycle on and off more than it should function properly. The stress of excessive cycling can cause damage to some of the most critical parts of a furnace, making the chance of early repair and replacement more likely.

Poorly Designed Ductwork Or Improper Installation Can Shorten A Furnace’s Life

Air is a gas, meaning it continuously moves to fill whatever space it is in. For example, air in a container spreads once its lid is removed, filling both the container and the surrounding area. The same principle applies to heated air from a furnace. With proper, sealed ducts, all heated air will move where it needs to go. When ducts have cracks or are poorly arranged, heated air will be wasted on areas that do not need it. Like a furnace that is too small, this overworks the unit.
Furnace function also relies on the proper installation of venting and fuel lines. When set up correctly, a furnace will use air and its energy source to run efficiently. Improper setup, inefficient airflow and energy intake damage the inner parts of the furnace. It creates a safety concern, too: leaked carbon monoxide exhaust.

Routine Maintenance Is Necessary To Get The Most Out Of Your Furnace

All furnaces have filters; changing them regularly is the easiest way to guarantee their efficiency. Filters affect air quality, but they’re most important for maintenance. A clogged filter restricts airflow, making a furnace work harder. It can also overheat, causing unnecessary shut-off and cycling. To avoid these adverse effects on lifespan, homeowners should replace furnace filters every season.

Additional maintenance is dictated by the energy source and size of a furnace. For example, an oil furnace will be checked more regularly than a gas or electric furnace because its fuel must be delivered and stored in a tank. It also creates more buildup, requiring more filter changes. A larger home may also have more frequent filter changes—because its furnace works with more air.

Homeowners should be aware of their furnace’s appearance, sounds, and surrounding area. Professional check-ups are advised if they are unsure of what they are looking at.

Temperature Fluctuations And Increased Energy Bills Can Signal That It’s Time For A New Furnace

Even the best-maintained furnaces eventually need to be replaced. Some signs are evident and alarming (like strange sounds or debris), but there are certain things all homeowners should keep in mind.

Old furnaces become very inefficient, affecting the airflow and temperatures in a home. If rooms or levels are not heating as evenly as they once were, requiring frequent thermostat adjustments, this likely means a furnace is ready to be replaced, especially if it has already been through repairs.

If temperature changes are not apparent, inefficiency may be more evident through energy bills. At the end of its lifespan, a furnace uses more fuel to get its job done, leading to a higher energy bill. If fuel or delivery charges have not changed, but overall energy expenses have, homeowners should consider investing in a new, more efficient furnace to last the next few decades.


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