How Often Should You Change Your Home Air Filter? Expert Guide
A clean air filter (top) compared to a dirty air filter (bottom). Replacing a clogged HVAC filter improves airflow, reduces energy costs, and helps protect your heating and air conditioning system.
Why do you need to change your home air filter?
Before we answer how often you should change your home air filter, it is essential to first understand the purpose of an air filter. All heating and air conditioning systems have a home air filter that can help remove allergens, dirt, dust, pet dander, and other particles from your home. In addition to harming your body and negatively affecting your breathing, these particles can damage your heating and air conditioning system, reducing its effectiveness and costing you money.
The United States Department of Energy reports that changing your home air filter can improve the efficiency of your HVAC equipment by 5% to 15%, which could result in hundreds of dollars every year.
How often should you change your air filter?
The simple answer is when it is dirty.
Generally, most 1” home air filters should be changed at least every 1 to 3 months. Larger, pleated cartridge-type home air filters (3″ to 5″) can last up to 12 months between changes.
However, how often to change your air filters depends on a few factors, such as:
- the type of air filter you are using (see below)
- the quality of the air inside your home
- the number and type of pets that live in your home
- the number of people occupying the home
- The level of air pollution in the city where you live
- the amount of construction around your home
A good rule of thumb is to check your home air filter once a month. A clean filter will help your heating and air conditioning (HVAC) system run more efficiently. Having a dirty home air filter is a good thing; it means the filter is doing its job by removing dust and pet dander from the air you breathe. One key is to use a filter with a good MERV rating.
What does MERV Rating have to do with choosing an air filter?
MERV ratings compare how effectively HVAC air filters capture airborne particles such as pollen, dust, mold spores, bacteria, and smoke. Higher MERV ratings provide better filtration but should be compatible with your HVAC system.
MERV stands for Minimum Efficiency Rating Value. This industry-standard rating system allows you to compare filters made by different
manufacturers. A MERV rating is a numerical value ranging from 1 (lowest efficiency) to 20 (highest efficiency) that indicates how well the filter captures and holds dirt and dust within a specified size range. The chart below shows the MERV ratings, corresponding particle-size ranges, and efficiency levels, as measured by the percentage of particles captured.
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Which Type of Air Filter Do You Need?
There is a vast difference between a cheap $1.98 fiberglass home air filter (you know… those bright blue ones encased in a flimsy cardboard frame) and a higher-quality pleated or HEPA filter.
- Economy panel fiberglass filters – A fiberglass home air filter is very thin and has a flat panel surface for trapping air particles. Originally developed to protect heating and air conditioning equipment, these air filters are not intended to improve indoor air quality. They can often be purchased for less than $1; unfortunately, they remove less than 10% of the air pollutants from your home. They have a MERV rating between 1 and 4.
- Pleated filters – Pleated air filters can remove up to 45% of the air pollutants from your home. The number of pleats per foot will impact the filter’s overall efficiency. They usually cost around $10 each and have a MERV rating of 10-13.
How Many Pleats Do I Need? The filter with more pleats per foot across the face will give you better airflow throughout your home. The more air flows through your house, the more often it passes through and is recirculated by the air filter. The result is cleaner air because of the higher frequency of air passing through the filter.
- Electronic filters – These filters are reusable but can get dusty quickly. Although the dust typically does not negatively impact airflow, it quickly affects the ability to filter the air.
- HEPA (High-Efficiency Particulate Air) filters – True HEPA filters deliver the best filtration, removing up to 98% of air pollutants. They have a MERV rating between 17 and 20.
Although HEPA filters are the most efficient, they restrict too much airflow to be used as a traditional furnace filter. A HEPA filter is highly efficient, but a significant amount of pressure is required to force air through it. A typical HVAC system will not be equipped to provide sufficient air pressure to operate a HEPA filter (which means no air would blow out of your registers).
Looking for Cleaner Indoor Air?
If you’re concerned about dust, allergies, pet dander, or airborne contaminants, replacing your HVAC filter is only part of the solution. Extreme Comfort’s Instant Quote lets you compare Good, Better, and Best HVAC systems, including advanced indoor air quality options such as whole-house air purifiers and high-efficiency filtration. Receive estimated pricing by email within minutes so you can choose the right solution for your home.
A clean home air filter will help save you money on energy costs, help improve the overall life expectancy of your HVAC system, and improve the quality of the air you breathe daily. Contact us today to have your air filter checked or replaced.
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Home Air Filter FAQs: The Questions Homeowners Ask Most
Q: How often should I change my home air filter?
A: Most 1-inch HVAC air filters should be replaced every 1 to 3 months. Larger 3- to 5-inch pleated filters can often last 6 to 12 months, depending on your home’s air quality, the number of occupants, pets, and how often your heating and air conditioning system runs. Check your filter monthly and replace it when it becomes dirty.
Q: What happens if I don’t change my HVAC air filter?
A: A dirty air filter restricts airflow, forcing your HVAC system to work harder. This can increase energy bills, reduce heating and cooling performance, shorten equipment life, lower indoor air quality, and potentially lead to expensive repairs.
Q: How do I know when my air filter needs to be replaced?
A: Replace your air filter if it appears dirty, is covered with dust or pet hair, has changed color, or airflow from your vents has noticeably decreased. A monthly visual inspection is the best way to determine when replacement is needed.
Q: What MERV rating is best for most homes?
A: For most residential HVAC systems, a MERV 8 to MERV 13 filter provides an excellent balance between filtration and airflow. Filters with higher MERV ratings remove smaller particles but may restrict airflow if your HVAC system is not designed to handle them.
Q: Can using the wrong air filter damage my HVAC system?
A: Yes. An air filter with excessive airflow resistance can reduce airflow through the system, making your blower motor work harder and potentially causing frozen evaporator coils, overheating, or premature equipment failure. Always use a filter recommended for your HVAC system.
Q: Do expensive air filters last longer?
A: Not necessarily. Higher-quality pleated filters generally capture more airborne particles and often last longer than inexpensive fiberglass filters, but replacement intervals still depend on your home’s air quality, pets, occupancy, and HVAC usage.
Q: Are HEPA filters recommended for residential HVAC systems?
A: Usually not. While HEPA filters provide outstanding filtration, they restrict too much airflow for most residential forced-air HVAC systems. Many homeowners achieve excellent indoor air quality with a properly sized MERV 11 to MERV 13 filter or by installing a whole-house air purification system.
Q: Do pets require me to change my air filter more often?
A: Yes. Homes with dogs or cats typically require more frequent filter changes because pet hair and dander accumulate quickly. Many homeowners with pets replace 1-inch filters every 30 to 60 days.
Q: Can changing my air filter lower my electric bill?
A: Yes. A clean air filter improves airflow, allowing your heating and cooling system to operate more efficiently. According to the U.S. Department of Energy, replacing a dirty filter can improve HVAC efficiency by 5% to 15%, helping reduce energy costs.
Q: Is it better to buy cheap air filters more often or expensive filters less often?
A: For most homeowners, a quality pleated filter offers the best value. It captures significantly more dust, pollen, and other airborne particles than inexpensive fiberglass filters while helping protect your HVAC system and improve indoor air quality.
Q: Which direction should my home air filter face?
A: The airflow arrow printed on the side of the filter should always point toward the HVAC equipment (toward the furnace or air handler), not toward the return air grille. Installing the filter backward can reduce efficiency and restrict airflow.