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How Long Does a Furnace Last, and the Warning Signs That It Needs to Be Replaced

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How long does a furnace last and what exactly does it do for your home? The furnace is one of the most important appliances in your home, as it keeps you and your loved ones comfortable during times when the weather isn’t the most hospitable.


“A furnace is a heating appliance used to heat and circulate air,” says Ron Natoli, a mechanical engineer and building systems expert for Robson Forensics in Pittsburgh.


How does a furnace work?


The thermostat controls the furnace and allows you to set a desired temperature. Once the thermostat registers a temperature outside of the one you set, the furnace kicks on (or fires up, in the case of gas furnaces) and the air will move through the heat exchanger, which warms it. From there, the blower motor kicks on and distributes the air throughout the home via the duct system.


Most furnaces are fuel-fired and use propane, natural gas, or fuel. Electric furnaces work well in warmer climates, but if you live in an area where winter overstays its welcome, it’s cost-prohibitive to use them. In this case, you’ll want to use a fuel-fired furnace.


How long does a furnace last?


Here’s some good news for homeowners: Furnaces have a considerably long lifetime, so you won’t have to worry about purchasing a new one very often.


“The average useful life of a furnace is between 18 and 20 years,” says Natoli. “With proper maintenance, this can extend the furnace’s operation to 25 or 30 years. But if you don’t properly maintain your furnace, they could fail in as little as 10 years.” These estimates for operational life apply to all types of furnaces.


So, what does proper furnace maintenance entail? It means annual cleaning and inspection by a professional. This is important because it allows the technician to examine parts such as the heat exchanger where problems, if they persist, could result in the furnace emitting carbon monoxide throughout the home, which is a huge safety issue for your family.


How much does it cost to fix a furnace?


Annual service for your furnace, including cleaning and inspection, can run between $50–$100, Natoli says. If a component in your furnace fails, the cost of repair can run from $150 to $600. And if you have to replace your furnace altogether, it can cost up to around $1,000 to buy a new one.


Warning signs that could mean it’s time to replace a furnace


Not sure if it’s time to replace your furnace? All you have to do is listen up.


“Any noise from the blower or motor, specifically a mechanical whining or a metal-on-metal sound, can indicate there’s a problem with the blower system or the main piece,” Natoli says.


Fouls smells coming from your furnace can also indicate—rather ominously—that it’s time for a new one.

“Check for abnormal smells such as natural gas, burning electric, and propane, as these can indicate that problems exist,” says Kyle Cullins, operations manager at Cullins One Hour Heating and Air in Lewis Center, OH. Abnormal smells can mean there might be a crack in the heat exchanger.


Bob Vila, the home improvement TV host, says other telltale signs include spikes in your energy bill when the usage is the same, having to repair your furnace often, or furnace short-cycling (when it turns on and off frequently).


Simple tips to prolong the life of a furnace


We said it once, but we’ll say it again: The best way to keep your furnace running well is through regular inspections. Also, it’s vital to replace your furnace filters regularly.


“A clogged furnace filter is akin to a marathon runner trying to breathe through a straw,” Cullins says. “We find a lot of system failures from a clogged filter.”


Need another reason keep your furnace in tiptop shape? Heating your home can represent up to 42% of your utility bill, so simple steps such as regular inspections and changing the filters can help you save money on energy bills while prolonging the life of your furnace.



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