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How Often to Change a Furnace Filter?

As the world continues to experience harsher weather, such as colder winters, a furnace has never been more vital. Your furnace’s filter is one component that ensures proper operation, but filters do not last forever. Filters are important because they help remove dust mites, debris, spores, pollen, smoke, dander, and smog, to name a few things.

Despite the fact that furnaces have evolved into incredible pieces of technology, they still need to be maintained regularly. The filter in your furnace is critical to its operation. It needs to be replaced on a regular basis to maintain the furnace running efficiently.

But “regularly” seems a bit ambiguous, doesn’t it? That’s why we wanted to figure out how often you should change your filter in order to get the most out of your furnace’s efficiency and performance.

Why Should You Replace Your Filter?

how often change furnace filter dust

Would you like to improve the efficiency of your furnace by up to 15%? According to the US Department of Energy, simply changing the filter at the appropriate interval can increase the efficiency of the system by that much! This is because filthy furnace filters impede a consistent flow of air from traveling through the system and into your living space.

The furnace will function properly if the filter is clean. A dirty filter, on the other hand, will stress the system, making it work far harder than it should. Finally, replacing your old filter with a new one has the potential to save you hundreds of dollars each year. That’s a lot of money saved!

The quality of your interior air will also improve if you change your furnace filter. It will be difficult to trap extra dust, filth, and other undesirable particles if you leave a blocked filter in place. As a result, some of those harmful particles will find their way into your home’s air via your air ducts.

It’s also worth noting that a clogged furnace filter increases the likelihood of a repair. The furnace will be subjected to considerable wear and tear as a result of unclean filters forcing the system to work considerably harder than it should. This increases the likelihood of a breakdown and subsequent repair. When you consider that an overworked furnace won’t last as long as it should, it’s simple to see why some homeowners change their furnace’s filter once a month just to be safe.

How Often Is Changing Furnace Filters Necessary?

how often change furnace filter replacement

The frequency with which furnace filters are changed varies from home to home. The type of furnace filter in use determines the frequency with which this activity must be done. If you walk down the filter replacement aisle at your local hardware store, you’ll see that there are many options – many different filter types to affect frequency changes.

Changing furnace filters should be done once a month to once a year, depending on the type of filter. There is a vast range of how often filters should be updated, just as there is a broad range of types of filters. Fortunately, changing furnace filters isn’t a guessing game. When you buy a new filter, the manufacturer includes product information that includes the recommended replacement frequency.

Size counts when it comes to determining how frequently you should change your furnace filters. Because thicker filters have more media to absorb pollutants, a 5-inch filter needs to be changed less frequently than a 1-inch filter. Filter efficiency has an effect as well; this is measured in MERV (minimum efficiency reporting value).

In general, this is how often changing furnace filters needs to be done:

  • For 1- to 2-inch filters, replace them every 1 to 3 months
  • For 3- to 4-inch filters, replace them every 6 to 9 months
  • For 5- to 6-inch filters, replace them every 9 to 12 months

More Factors that Affect Frequency of Changing Furnace Filters

As we mentioned, size and efficiency are two attributes that affect the frequency-changing furnace filters. In addition, there are various factors specific to your Cincinnati area household that have a greater impact on how often you really need a new filter.

Indoor Air Quality

how often change furnace filter air quality

If you have poor indoor air quality, your furnace filter will not last as long as it would in a household with acceptable indoor air quality. Indoor air quality devices such as air purifiers and air cleaners minimize pollutant volume, allowing your furnace filter to absorb fewer particles. In houses without this equipment, the furnace filter is the sole line of defense against airborne contaminants, so it fills up faster.

Home Occupancy

The number of people who live in a house has an impact on the furnace filter’s usable life. Change furnace filters more frequently in a large household than in a home with only one or two occupants. People introduce a lot of toxins into the household environment, thus the more people you have, the more toxins the filter will have to deal with.


how often change furnace filter pet hair

Fur and dander are shed by pets, which are taken up by airflow and circulated around the house via the HVAC system. The usable service life of a filter is reduced by around 30 days for every furry family member residing in your home, so you’re changing furnace filters more frequently.

Heating & Cooling Usage

Filters have a shorter usable service life when your home’s heating and cooling equipment is heavily used because air is cycled more frequently, giving the filter more chance to pick up impurities and become blocked. Homeowners often change furnace filters more frequently in the summer and winter than in the fall and spring.


If you or a member of your family suffers from allergies or asthma, you should change your furnace filters more frequently. This helps to ensure that toxins that cause symptoms are eliminated from the air supply in your home.

Never Forget Another Filter Change!

Not only for your HVAC system but for the entire home, changing furnace filters is essential. When your HVAC equipment is hidden away and out of sight, it’s all too easy to overlook a filter change, but it’s critical that you do so.

It’s a good idea to inspect your filter at least once a month to see how it’s doing. Your furnace filters may need to be changed sooner than expected depending on your system, but it’s impossible to tell if you never check! Once a month, take a look at the filter and replace it if the surface media becomes fully covered with contaminants.

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