How Long Do Furnaces Last and How Can I Extend the Life Span of Mine?

When you hear the furnace start to rattle or notice the vents don’t seem to be blowing out hot air quite like they used to, you may start to wonder: How long do furnaces last? Could it be time to replace your old furnace? 

No matter the type of furnace you have, furnaces come with an average life expectancy. But whether or not they last that long can depend on many factors, from the furnace type, brand, and size you purchase to how you maintain the unit over the years. Here’s what you can expect when it comes to the life span of a furnace.

Average Life Span of a Furnace

An average furnace lasts about 15 years, with most working efficiently for about 15 to 20 years. After that, general wear and tear can cause the furnace to work harder to provide the same amount of heat it’s been providing you with all these years, which can lead to costly utility bills. That’s why when your furnace starts getting up there in age, it’s best to hire a local furnace installer to replace the old furnace with a newer, more energy-efficient model.

How Long Do Different Types of Furnaces Last?

Different types of furnaces can have slight differences in their life spans based on how efficient the different fuel sources are. You can expect the following life expectancy for these common furnace types:

• Electric: 20–30 years

• Natural gas: 15–20 years

• Propane: 15–20 years

• Oil: 15–25 years

• Wood: 10–20 years

While it’s not technically a furnace but another type of heating element, a heat pump has a life span of about 10 to 15 years. That’s because the heat pump works year-round, providing both heating and cooling. This is something to keep in mind when considering heat pump costs and whether to install a heat pump versus a furnace.

Factors That Influence Furnace Life Expectancy

From the furnace’s brand and size to how it is installed, there are many factors that influence how long furnaces last. Even your preferences for where to set the thermostat can impact the life span of a furnace, so it’s no wonder your parents were always adamant about not touching the thermostat when you were a kid.

Brand

While it’s tempting to buy the least expensive model from an unknown brand to save money on new furnace costs, the brand and model of your furnace will impact its life span. Some brands have been around for decades and are known for manufacturing high-quality furnaces and parts, or brands may offer premium, higher-quality models and more budget-friendly options with standard-quality parts. 

Furnace Size

Determining the right furnace size for your home is an essential step in buying a new furnace. Furnaces that are too small will have to run more continuously to try to keep the home heated to the thermostat setting, and this will wear out the furnace parts. But a furnace that is too large can cause problems, too. Oversized furnaces will short cycle, or turn on and off, more frequently, and this process puts more strain on the furnace parts.

Installation

There are a number of things that can go wrong with a furnace installation. An untrained furnace installer may fail to properly seal the air ducts or install the wrong size of air ducts or furnace, or they may install the fuel lines and exhaust vents improperly.

Improper installation will cause the system to work less efficiently, and it can cause fire risks or exposure to combustion gasses. Prolonged exposure to combustion gasses such as carbon monoxide can be deadly, so it’s important to always work with a licensed, highly rated furnace installer when putting a new furnace into your home.

Thermostat Settings

You may love to feel the toasty air blowing through the vents in the cold winter months, but your furnace doesn’t exactly love churning out all of that hot air. Setting your thermostat too high or too low can make the system work harder or put unnecessary wear on parts inside the unit, which will shorten the life span of the furnace.

The U.S. Department of Energy recommends setting a furnace thermostat anywhere between 68 degrees and 70 degrees Fahrenheit during the day while you are home. At night or if you aren’t home, set the thermostat a few degrees lower. Not only will this extend the life expectancy of your furnace, but it will also save you money on heating costs.

Maintenance

Furnaces require regular maintenance to perform their best. This involves changing the furnace filter at least every 90 days and scheduling an inspection, cleaning, and tune-up at least once per year. By having an HVAC professional handle these services each year, they can keep the system running smoothly and fix any minor issues before they become major, energy-draining problems.

Location

You may not have much say in where a furnace can go in your home, but it’s helpful to know that the location can impact how long a furnace lasts. Furnaces work best in a climate-controlled space, like a utility closet inside the home or in a garage.

Furnaces in attics are exposed to more heat over the course of the year, which can shorten their life span. Furnaces in crawl spaces can be exposed to more heat in the summer and cold in the winter, plus they may be accessible to pests.

How to Extend the Life Span of a Furnace

Like any other appliance in your home, a furnace requires a little TLC from time to time to keep it running as efficiently as possible for as long as possible. Some furnace maintenance tasks will require help from a pro, but there are a few things you can do yourself, too. 

Change the Filters

The furnace filters need to be changed about every 90 days, but if you live in a home with pets, someone who smokes, someone with allergies, or a higher number of household members, you may want to change the filters more frequently, about once per month.

Schedule an Inspection

You need to schedule a furnace inspection at least once per year, typically in the fall. That way, an HVAC professional can clean the system and repair any issues before the colder temperatures set in. When scheduling the inspection, you should also have a pro come to clean the furnace and do a tune-up.

Keep It Clean

In addition to scheduling professional cleanings once per year, you should keep the furnace area clear of any objects or debris. Clean the area and move any cardboard boxes, storage bins, or other clutter. Not only will this help the furnace work more efficiently, but it can also minimize fire risks.

Signs It’s Time to Replace Your Furnace

Whether you lived in your home when the existing furnace was installed or not, you may wonder how long furnaces last and how to tell it’s time for a replacement. There are several telltale signs to watch (and listen) for that will clue you in to start shopping for a new furnace.

Age

Most furnaces only last 15 to 20 years, so the age of the furnace is important to consider when deciding whether to repair or replace a furnace. If you aren’t sure of your furnace’s age, look for the model number and serial number inside the service panel cover, on the rating plate, or on the back of the unit. You can either research the model and serial number online to determine the age or look at the serial number.

Typically, the first four digits will reveal the month and year the unit was manufactured, or the second through fifth digits will reveal the month and then the week of the year of manufacturing. However, this isn’t always the case. You may need to contact the manufacturer and provide your model and serial numbers to get the date, or you can hire an HVAC professional to help you.

Visible Damage

If your furnace has visible cracks or rust, it’s probably time to replace the unit. These damages may not be serviceable, and cracks can lead to combustion gas leaks. 

Unusual Noises

Furnaces may naturally make some noises here and there, like a click when they turn on or a quiet humming as they heat the air. But loud, abrupt noises like grinding, screeching, banging, or rattling may be a sign to replace the furnace.

Repair Frequency and Costs

If it seems like you’re making a service call to a furnace repair person every other month, it’s probably time to replace the furnace. Another way to determine if the furnace is past its prime is by considering your repair costs. If your furnace repairs cost more than 30% of the cost to replace the unit and the unit is under 15 years old, it’s going to be more cost-efficient to order a replacement.

Common Gas Furnace Problems

According to Angi data, nearly 41% of customers reported that their gas furnace or forced air heating system doesn’t provide heat or doesn’t get hot enough. Other common problems include pilot light out, makes odd noises, smells funny, and cycles off too rapidly or runs constantly.