If your home has a gas furnace that is getting up there in years, you’re probably wondering how long you can reasonably expect it to last before it gives out and you need to replace it. On average, a gas furnace will usually work effectively for somewhere around 15 years, but the lifespan of a furnace can vary quite a bit based on the type of unit if it’s the correct size, and whether it has been properly maintained every year.

Plenty of furnaces last longer and may keep heating effectively for 20 years or more. However, we would generally recommend not waiting too long and replacing your furnace if it’s 15 years old or no longer works as effectively. This way, you can ensure that your home stays comfortably warm throughout the winter and eliminate the risk of your furnace suddenly giving out. In this article, we’ll discuss the different factors that can affect the lifespan of a furnace and also how to know when it’s time to have your furnace replaced.

Which Type of Furnace Lasts Longest?

The type of furnace you have and how energy efficient it is can directly affect how long it lasts. A high-efficiency condensing furnace will normally have a longer lifespan than a medium-efficiency conventional furnace. The reason is that condensing furnaces work more efficiently, so they typically won’t have to run as long as conventional furnaces do. The shorter a furnace’s heating cycles are, the less wear and tear the unit’s components will suffer. In turn, this decreased wear and tear lessens the chances of the furnace breaking down and forcing you to pay for costly repairs or the furnace giving out sooner.

Both conventional and condensing furnaces can be single-stage, two-stage, or variable-speed units. The lifespan of a single-stage furnace will typically be shorter than for a two-stage or variable-speed unit. This is because single-stage furnaces can only run at 100% capacity, which means they produce lots more heat at one time. This results in single-stage furnaces typically cycling on and off two to three times an hour. This continual cycling can lead to various components in the furnace wearing out more quickly, leading to the unit needing more repairs or not lasting as long.

Two-stage furnaces are superior as they can operate at full and medium power. A two-stage furnace will normally operate at around two-thirds of its full capacity approximately 80% of the time. In the Jacksonville area, a two-stage furnace may never, or only very rarely, run at full capacity since our warmer climate means you generally don’t need the unit to produce that much heat at a time. When operating on medium power, a two-stage furnace will use lots less energy. The unit is also under less strain whenever it’s not running at full capacity, decreasing the wear and tear on its components.

Variable-speed furnaces will almost always have the longest lifespan. Instead of just having one or two power settings, variable-speed units have a few dozen settings and can operate at anywhere between 25% and 100% capacity. On colder days, a variable-speed unit will run almost constantly at a much lower speed, which helps to prevent issues that can result when it continuously cycles on and off.

The Importance of Having a Properly Sized Furnace

Another essential factor that can significantly affect how long a furnace lasts is whether the unit is the correct size for your home and the local climate. An undersized furnace will produce less heat than what is needed to effectively keep the home warm, which means each heating cycle will be much longer than it should be.

If the furnace is oversized, it will produce so much heat that it only runs for a few minutes at a time. This leads to the temperature constantly fluctuating and the furnace short cycling, which is where it continually cycles on and off multiple times an hour. Oversized furnaces are also prone to overheating, which can damage the electrical components or cause the unit’s heat exchanger to crack. These issues typically result in an undersized or oversized furnace having a far shorter lifespan and leading to much higher heating costs.

How Annual Maintenance Helps Protect the Life of a Furnace

The most important thing you can do to protect the life of your gas furnace is to have it inspected and serviced or maintained every year by a certified HVAC technician. Regular maintenance will help to keep your furnace working energy efficiently and effectively, which means each heating cycle will be shorter and the furnace won’t be under as much strain. Annual inspections are also essential for identifying any issues that could hamper the furnace’s performance. Even minor problems can have a major impact on a furnace’s performance, which can force it to work much harder and lead to more serious problems arising.

In addition to having your furnace professionally maintained, it’s also important that you replace or clean the furnace filter regularly. The filter will always slowly start to clog up with dust and debris, which limits the amount of air that the blower can draw through it. When less air can flow through the filter, the furnace will produce less heat and have to run for a longer time to fully heat your home. Not only will this lead to higher heating costs, but it also puts more strain on both the furnace and the blower. If the filter is clogged and there isn’t sufficient cool air flowing over the heat exchanger, the furnace can also start having issues where it frequently overheats. The best way to prevent these problems is to check your furnace filter monthly and replace or clean it at least every 90 days.

How to Know When It’s Time to Schedule a Furnace Replacement

Another reason that it’s important to have your furnace inspected every year is that it makes it easy to determine when the unit is starting to give out and should be replaced. There are also some telltale signs that can help you know if your furnace is beginning to wear out, such as if the unit is more than 10 years old and your heating costs have started increasing year after year. If your furnace is constantly shutting down too soon due to overheating or some other issue, it’s definitely time to schedule an inspection.

Depending on the specific cause of the problem and the extent of the issue, it’s sometimes better to replace your furnace even if the problem can be repaired. In this situation, it usually comes down to how much life your furnace has left and what it will cost to replace the problem. If your furnace likely only has a few years of life left and you’re looking at having to spend over $500 to repair it, the smarter financial decision will usually be to install a replacement unit.

At J&W Heating and Air, our certified technicians can diagnose any issues your furnace has and help you decide whether repairing the problem or installing a replacement is the better choice. We repair and service all brands, models and types of furnaces, and we also offer professional furnace replacement services as well as the full range of air conditioning services. If you have any questions or need any heating or AC service in the Jacksonville area, give us a call and we’ll be happy to help however we can.

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