AC filters typically last for around 30 to 90 days, but that window can shrink or increase depending on various factors. These variables include things like indoor air quality, how often the system is used, and the air filter’s material and efficiency rating.
In this article, we’ll take a closer look at AC filters and how often you really need to replace them.
Key Takeaways
• Typical Lifespan: Most residential AC filters last for approximately 30–90 days before needing replacement.
• Variables Matter: Factors like indoor air quality, HVAC usage, pets, and allergies can substantially shorten the lifespan of an air filter.
• Check Them Monthly: It’s best to inspect your AC filter every 30 days. If it looks dirty or clogged, it’s best to replace it.
• Higher MERV, Shorter Life: AC filters with a higher MERV rating catch more contaminants, but they usually need changing more often.
• Neglect Costs More: A clogged filter strains your system, raises energy bills, and reduces indoor air quality. So, it’s always preferable to replace an AC filter too early rather than too late.
What Are AC Filters Made Of?
AC filters can be made from a range of different materials, and each type of air filter offers distinct pros and cons.
Fiberglass
Fiberglass is one of the most popular materials for making AC filters. Fiberglass air filters are made with spun glass fibers in a cardboard frame. Generally, these filters are quite affordable, but they aren’t as efficient at filtering contaminants as some other types of filters.
Pleated Polyester or Cotton
Another common type of AC filter is the pleated polyester or cotton filter. These filters are made of densely woven fibers, and they generally feature greater surface area for trapping smaller airborne particles.
Electrostatic Media
Although less common, some AC filters are constructed with synthetic fibers. These fibers create a static charge, which attracts dust and pollen in the air.
How Do AC Air Filters Work?
Whenever your air conditioner runs, its blower pulls warm indoor air through the return ductwork. As this air passes through the AC filter, the fibers of the filter catch and trap any contaminant particles. This often includes dust, pollen, pet dander, and various other pollutants. This allows substantially cleaner air to move across the system’s evaporator coil. There, the air is cooled and circulated back into different areas of your home.
When your AC air filter is clean and functioning properly, it keeps the air conditioner clean, functional, and energy-efficient. It also helps ensure that you and your family consistently have clean, healthy air to breathe.
Understanding MERV Ratings
What Is a MERV Rating?
MERV, or Minimum Efficiency Reporting Value, is a scale developed to rate how efficiently air filters capture particles between 0.3 and 10 microns in size. The higher the filter’s MERV rating is, the smaller the particles it can trap.
MERV Rating Scale Breakdown
AC filter MERV ratings can be evaluated using the following scale:
MERV of 1-4
Air filters with a MERV rating between one and four are typically used for basic residential HVAC systems. They can typically capture dust bunnies and large particles of lint.
MERV of 5-8
These filters can consistently trap mold spores, pet dander, and pollen. They are commonly found in standard and high-efficiency household HVAC units.
MERV of 9-12
AC filters rated between nine and 12 on the MERV scale can capture a variety of very small particles, including fine dust, lead dust, and auto emissions. These filters are good options for high-end residential HVAC systems, particularly for households with advanced indoor air quality needs.
MERV of 13-16
Air filters rated 13 or higher are generally only used in environments that require extreme filtration, such as hospitals and commercial clean rooms. These filters can trap bacteria, smoke, and even sneeze droplets.
Choosing the Right MERV Rating
When choosing an AC filter for your household, you’ll need to consider your specific indoor air quality needs and goals. For most homes, a MERV rating between five and eight will be fine.
If you have pets, or anyone in your household suffers from allergies, an AC filter rated between nine and 12 may be a better option.
An air filter rated 13 or higher will provide exceptional filtration, but it can also restrict the cooling system’s airflow. Before you go this route, you’ll want to confirm that your AC unit’s blower can handle the extra resistance.
How Often Should You Change Your Air Filter?
While 30 to 90 days is the standard guideline for changing your AC filter, a great general rule is to check the filter monthly and replace it whenever it looks dirty.
Additionally, you should consider all of the following factors:
- Pets: Because of dander and hair, pets in your home can substantially shorten the lifespan of your AC filter.
- Allergies or Asthma: If anyone in your home suffers from allergies or asthma, you’ll want to replace your air filter every 30 days—especially during peak seasons.
- Smoking Indoors: In homes where indoor smoking is a regular occurrence, it’s usually best to change the AC filter every 20 to 30 days.
- System Usage: Ultimately, running your air conditioner more frequently will lead to its air filter getting dirty more quickly. So, the more often you have the AC on, the more frequently you’ll need to replace the filter.
What Happens if You Don’t Replace AC Air Filters?
If you fail to replace your AC filter often enough, it can lead to quite a few negative effects, both in the short term and the long run.
Short-Term Effects
Dirty AC filter can hamper the airflow of your cooling unit, resulting in reduced comfort and uneven temperatures around the house. You may also start to notice higher energy bills as your AC unit is forced to work harder and burn through more electricity.
Additionally, a dirty filter can lead to dust buildup on vents and surfaces around your home, creating a dirtier atmosphere and worsening indoor air quality.
Long-Term Effects
Letting dirty AC filters linger can also have several long-term effects. For example, it may cause your air conditioner’s evaporator coils to freeze due to restricted airflow. This can lead to expensive repairs and major hassle.
Failing to replace your AC filter on time can also cause your AC unit to be overworked, which may eventually lead to premature system failure. Additionally, waiting too long to change your AC filter can greatly decrease your indoor air quality. More contaminants in the air can potentially cause allergies, respiratory issues, and unpleasant odors.
What About HEPA Filters?
High‑Efficiency Particulate Air (HEPA) filters remove 99.97% of particles down to as small as 0.3 microns. While these filters are wonderful for air purifiers and hospital clean rooms, most residential HVAC systems aren’t designed for their intense airflow resistance.
If you want HEPA‑level filtration in your home, consider investing in a whole‑house air cleaner. Rather than swapping a standard AC filter for a HEPA panel, a professional can add one of these cleaners to your existing ductwork.
Things to Consider When Buying an AC Air Filter
When you’re purchasing an AC filter for your home, there are a few things you should always consider:
- Always match the filter size and maximum MERV to your HVAC system recommendations.
- Remember that things like pets, smoking indoors, and allergies will require a higher MERV rating or more frequent filter replacement.
- Keep in mind that premium filters cost more, but they also protect your HVAC equipment and can improve your health.
- Certain types of air filters can be relatively difficult to find consistently. Consider choosing a type of AC filter that you can easily find locally or online.
Need AC Maintenance in Niceville, FL?
If you live in Niceville or the surrounding area, you can always count on the expert team at Service Minds One Hour for quality HVAC services. Whether you need air conditioning maintenance, repairs, or installation, your service will be handled by friendly, qualified technicians.
Our team will be professional, respectful, and punctual at all times. We’re always on time, or you don’t pay a dime. Simply contact us today if you have any questions or would like to schedule an appointment.
Final Thoughts
AC filters might seem like small, unimportant parts, but they play a huge role in your comfort, health, and energy costs. If you want to keep your home functioning smoothly year-round, remember to inspect your AC filter monthly and replace it at least once every 30 to 90 days.
Additionally, remember that you’ll need to change your AC filter even more often if you have pets, suffer from allergies, or rely on your AC unit frequently.