How Long is an Average Furnace Life?

Key Points

• Furnaces last between 15 and 30 years on average.
• Factors that age your furnace include the use case, quality of installation, frequency of use, and size.
• Fix or replace your furnace when dealing with rising energy costs, uneven heating, unexpected operational sounds, frequent repairs, constant cycling, inadequate heating results, or poor air quality.
• When choosing a new furnace, look for a high AFUE rating, a powerful blower motor, a comprehensive warranty, and a compatible fuel type.

Is your furnace ready to keep you and your loved ones cozy through another long winter? Your home should be your sanctuary that’s shielded from frigid outdoor temperatures, and your furnace the knight in shining armor keeping your ambiance safe. Just like real knights, your furnace has a finite lifespan to take into account. Before you assume it’s in good enough shape to make it through another winter, take a step back and ask a few questions. When did you purchase your system? How efficient was it last year compared to the year before? Did you have someone inspect it before the season? When it comes to questions about furnace life expectancy, IWAE is here to make sure you have all the info you need to gain optimal furnace performance.

How Long Do Furnaces Usually Last?

The average furnace lasts between 15 and 30 years. Some experts recommend replacing your furnace after 15 years, but most agree that 30 years is the maximum furnace life span. This is because once your furnace has passed the 15-year mark, any repairs you make may cost more than what would be saved by buying a new, more efficient unit. Furnace technology is constantly improving, so it's important to stay up-to-date with all available options when deciding whether to repair or replace your old unit.

What Causes Furnaces to Age?

High-quality systems obviously last longer than low-quality systems, but many factors influence how quickly your furnace ages, such as:

• Quality of installation: If a furnace is installed improperly, unnecessary strain is put on the unit that shortens its lifespan.
• Frequency of use: If you use your system more and live in a colder climate, this will put more stress on your furnace. This is especially true if the unit is older and less efficient.
• Temperature management: How well you manage your comfort will also affect the longevity of your furnace. If you keep your house cooler in the winter, especially when no one is home, your systems will not overexert themselves. Using set temperatures, preferably for a minimum of 8 hours at a time, will also be easier on your furnace than frequently changing your settings throughout the day.
• Appropriateness of size: Furnaces that are properly sized for their homes will last longer. If it's too big or small, it will cycle more than it needs to and wear down faster.

When to Fix or Replace a Furnace

While furnaces generally last at least 15 years, it's impossible to know how long an individual unit will be able to function at its peak capacity. Whether it’s before that milestone or after, there are several signs that point to the furnace needing some TLC. A single broken part and end-of-life indicators often overlap, but that doesn’t have to leave you confused about what to try first. Let’s look at when you can try a repair first and when it’s time to bite the bullet.

Frequent Cycling

Most modern furnaces shouldn't need to cycle on and off to maintain a comfortable temperature. If you've noticed your furnace cycling frequently, don't ignore this sign. It could indicate a broken part or a fully failing unit. We suggest calling in a qualified technician to take a look at the unit to see if you can enjoy full functionality again with simple repairs.

Air Quality Issues

Sometimes, air quality issues can be caused by something as simple as needing to replace or clean the furnace filter. Even some more complex part failures are fixable with repairs. However, as a unit nears the end of its life, it may lose the ability to reduce humidity or prevent excessive dust from entering the air you breathe in your home. If the cost of repairing it is prohibitive, or if replacing it is the only option, don’t fret. Although furnaces aren't cheap, newer models are more efficient than ever before. This means that upgrading to a new model will save you on energy costs, helping you recoup your costs over time.

Loud Noises

Another telltale sign of a furnace in need of support is loud and unusual noises, such as:

• Popping: Popping is the result of temperature fluctuations in your furnace. This noise is coming from components affected by this temperature change.
• Screeching: This sound most likely means that the blower motor has been damaged, although it can also suggest a damaged belt or pulley.
• Humming: A low humming noise is normal and is caused by the blower motor in operation. If the noise becomes noticeably loud, it's time to look into the cause.
• Rattling: If you're hearing a rattling sound, this may mean loose equipment or ducts. Speak with an HVAC professional about whether this warrants a replacement.
• Booming: If you hear a booming sound, this may be a sign of a serious gas emission problem. This sound is generally caused by a short delay during the ignition process. If this is accompanied by a lingering gas smell, this is a clear sign that the ignitor or the whole unit will need to be replaced.
• Clicking: Clicking noises often mean your igniter or flame sensor needs repairs. Fortunately, this noise is not uncommon and can often be repaired during a standard furnace repair.

Uneven Heating

As your furnace ages, it will become less and less able to distribute heat throughout the rooms and floors of your house. Uneven heating can be a side effect of issues in the ductwork or a broken part, but if you notice subtle changes in temperature between different rooms in your house, it's most likely time to start looking for an upgrade.

Inadequate Heating Results

Is your home just not warm enough anymore? If your heat is on but you're still feeling cold indoors, this is one of the most obvious signs that something is wrong. It's important to note that this issue could be caused by other things, such as a malfunctioning or broken thermostat, but if there are no alternative explanations, don't push your system into overdrive. Have your furnace professionally inspected. Repairs are a potential fix in some situations, but more often than not, replacing your unit is the best course of action.

Rising Energy Costs

Your furnace consumes more energy than most other appliances in your home, which means that its efficiency is integral. Once winter begins, take a good look at your energy bills. If you notice you're paying significantly more than in previous years and your energy costs have stayed the same (or similar enough that the increase is worrisome), you will want to consider an upgrade. While repairing your unit may boost its efficiency a bit, newer models are more efficient and tend to perform at their peak efficiency for longer. Once you hit this point, don’t choose a Band-Aid. Fix the problem at its source by getting a new furnace; it’ll most likely provide you with more savings in the long run.

Frequent Repairs

Having your furnace serviced regularly? If you’re already spending hundreds or thousands for repairs, it's time to cut your losses and look for a new unit.

How to Extend Your Furnace’s Life Span

One of the best ways to extend your furnace's lifespan is to have it installed by a professional. Improper installation is one of the biggest issues associated with gas furnaces in the United States. Poor installation can easily compromise the performance of any furnace, even those that are high-quality, affecting how it heats up and stabilizes temperatures. Homeowners who choose to install their furnaces themselves often end up with the following issues:

• Ductwork with leaks and cracks

• Poorly designed drainage systems

• Improperly sized furnaces

• Poorly designed air distribution systems

• Rusting due to installation in a humid area

• Improperly designed exhaust systems

For these reasons, you must take your furnace installation seriously. Have the setup handled by a licensed professional. This is the biggest factor in lengthening the life expectancy of your furnace. There are a handful of other ways to prolong your furnace’s lifespan, including:

• Adding a programmable thermostat

• Sealing leaks around the home

• Reducing humidity

• Cleaning filters regularly

• Scheduling yearly maintenance

Add a Programmable Thermostat

Programmable thermostats allow homeowners to control the temperature of their homes automatically. This decreases the amount of time that their furnaces run needlessly, saving time and money in the process.

Seal Leaks Around the Home

If there are leaks in your air ducts, some of the heated air will escape rather than being delivered to your living space. This means that the furnace will have to work harder to heat your home to the desired temperature. Once you seal leaks in the ductwork, doors, and windows, you’ll find an increase in your furnace's efficiency and lifespan.

Reduce Humidity

If a furnace is in a humid environment, it will rust more quickly and shorten its lifespan. The best way to avoid this problem is by not installing it in a humid environment, but that isn’t always a real possibility. If your existing system is in a humid place, using a dehumidifier can make a big difference.

Clean Filters Regularly

Regularly cleaning the filters on your furnace will prevent dirt and dust damage. It also prevents these particles from circulating in your home, reducing the number of household allergens so you and your loved ones can breathe easy. We recommend that you check your filters at least once a month when your furnace is in use. The filter is most frequently found between the blower and the return air duct. Removing it is generally an easy task, although you might need a screwdriver to pry open the door. After you've cleaned or replaced the filter, make sure you insert the filter in the correct direction (this should be indicated on the filter itself). Be sure to consult your owner’s manual if you have any questions or concerns about the process.

Schedule Yearly Maintenance

Just as with any other important appliance in your home, proper maintenance is critical for your furnace. To make sure your unit is operating with the highest efficiency possible and mitigate the likelihood of costly repairs, you should have your furnace inspected by a professional at least once a year. Ideally, this should be at the end of the winter season. If your HVAC system also has AC, both systems should be inspected at the same time.

What to Look for in a Replacement Furnace

When shopping for a furnace replacement, it's important to learn about all the available options. Characteristics such as size, type, and efficiency all affect how much it costs to run during the coldest time of year. One of the most important considerations is efficiency. We suggest you buy the most efficient furnace your budget allows, as this will save you the most money in the long run on your utilities. For more detailed information, check out our furnace buying guide.

Furnace efficiency defines how much of the fuel that goes into your furnace becomes heat for your home. This is measured in terms of a percentage and is referred to as the Annual Fuel Utilization Efficiency (AFUE). To meet regulations, furnaces must have at least 80% AFUE. However, some models have efficiencies as high as 95%, meaning that only 5% of the energy consumed by the unit escapes through the flue. Higher efficiency means you use less fuel to warm your home, which can translate to lower utility bills. 

There are a range of other factors to keep in mind when looking for a new furnace. These include:

• Fuel source 

• Type of system

• Blower speed

• Warranty

• Installation quality

Fuel Source

Furnaces typically use one of three fuel sources: natural gas, oil, or electricity. Each have their own unique characteristics that are worth taking into consideration.

• Gas: Gas furnaces traditionally consume natural gas and are the most economical furnace type for heating your house when outside temperatures are below freezing. If you already have a gas furnace, replace it with another gas furnace. Upgrading to a new gas furnace from another fuel source can be expensive upfront, but it can save you money in the long term. Many natural gas furnaces can be converted to work with LP, or liquid propane, to work effectively in areas off the gas grid.

• Oil: Oil furnaces are also reliable and powerful heat sources, though they tend to take up more space than gas equivalents. They tend to be dirtier and more costly than natural gas furnaces, although this depends on the price of oil. However, oil is usually used in regions without gas lines and is particularly common in older houses.

• Electric: Electricity is another alternative to natural gas for home heating, though electric furnaces tend to be very expensive to operate. An electric furnace has to create original heat out of electricity, a process that can significantly increase your energy bills. A more economical option is an electric heat pump, which consumes less electricity to transfer heat from one air stream to another. These systems also serve as air conditioners in the summertime. Depending on your situation, an electric heat pump may meet all of your cooling and heating demands.

Type of System

There are two main layouts of heating and cooling systems — split systems and package units:

• Split: Split systems are the most common type of heating and AC systems. They consist of indoor components of a furnace and an evaporator coil that rests over the furnace, as well as an outdoor condensing unit.

• Package: Package systems provide the same heating and cooling services that split systems do, but unlike split systems, the cooling and heating components are all housed in a single, outdoor unit. This option is designed for homes that don't have basements, attics, or crawl spaces to house indoor HVAC equipment. They’re a worthwhile consideration if you have a split system but want to free up some space in your home.

Blower Speed

A furnace can have one of two blower types: fixed-speed or variable-speed. Variable-speed blowers run quietly while fluctuating how fast the blower operates as it pushes air through the ducts in your home, ensuring your home receives the exact amount of hot air required to craft your preferred ambiance. Single-speed blowers are more traditional, only boasting the ability to turn on or off. With fixed-speed blowers, operation is noisier, and it’s more difficult to achieve a consistent temperature in the house. This is due to the higher speed at which the blower runs to maintain a set temperature.

Warranty

The length of the warranty that comes with the system says a lot about its durability and lifespan, so try to pick a model with the longest warranty possible.

Installation Quality

Even if you choose the most efficient heating system currently available, poor installation will leave it operating lower than its indicated efficiency. Not only that, but an incorrect setup can lead to a variety of performance problems that will be costly in the long run. Some homeowners are tempted to install their heating units themselves to save money, but you shouldn’t give in to this temptation. Heating systems are more complicated than most people think, so self-installation is all but guaranteed to lead to problems.

Get a New Furnace with IWAE

Whether your furnace is on its last legs or simply needs a tune-up, don’t drag your feet. Leaving issues with your system unresolvedcan cause larger problems down the road. Your home needs reliable and efficient heating results, so don’t leave your family to suffer through inadequate warmth this winter. If you have any questions or concerns, don’t hesitate to reach out to our customer service experts. They can help you decide the best path forward, from swapping out an air filter to ordering a new furnace and everything in between.