When Should I Replace My HVAC Air Filter?

Individuals need to change the air filters in their HVAC systems regularly. Doing so ensures the air circulating throughout the home is clean. Furthermore, a clean air filter improves the efficiency of the system while keeping energy bills under control. A failure to replace the air filter regularly can lead to system breakdowns and a shorter lifespan of the unit. 

Homeowners often forget this essential task because life gets busy. They believe they have already replaced the filter, and it gets put on the back burner. As a result, they find their energy bills increase or they have a system failure of some type. Fortunately, many companies now incorporate system reminders into their units or services. These reminders let the owner know when they need to change the filter or carry out other maintenance tasks. 

Changing the filter takes little time. Many people find they can complete this task in a matter of minutes. That includes retrieving the new filter from its storage place in the home, removing the used filter, and installing the new one. A trip to the store to purchase a new filter often takes less time than one would spend waiting for an HVAC technician to arrive at their home, diagnose the problem, and make the repairs required as a result of the dirty filter. 

How often should a homeowner change their HVAC filter to prevent issues? Why is this important? Are there situations where the homeowner should replace the filter more often? The following recommendations apply to many homes in the U.S. However, ask your HVAC services technician what they suggest, as they know the home and system. 

The Importance of Changing the Air Filter Routinely

Air filters work to trap particles in the air. These particles include dust, dander, pet hair, and more that can make their way into the lungs of individuals living in the home if left unchecked. Over time, the filter becomes clogged with the particles, which prevents the air from making its way to the HVAC unit. The system must work harder to heat or cool the home, and this is only one of many problems that may arise from a dirty filter. 

A clogged air filter results in high energy bills because of the system being overworked. The system runs for longer periods when the filter is dirty. Homeowners might not recognize the system is running longer until they open their energy bill for the month and it has increased significantly. When this happens, they often call a service tech to come out and check the system. Changing the air filter may bring the bill down to a reasonable level without the need for our technician to come out and check the system. 

Individuals in the home may become sick more often. They rarely make the connection between the dirty air filter and their health. When the filter can no longer trap dust and allergens because it is dirty or clogged, these particles make their way throughout the residence. When they do, they can trigger asthma attacks, respiratory illnesses, and more. These particles may build up in the ductwork, which leads to the need for duct cleaning to prevent additional attacks. Replacing the air filter costs less than medical bills resulting from an allergy or asthma attack, and a person’s health is priceless. 

A clogged filter strains components within the HVAC system. For instance, when airflow within the HVAC system decreases, the fans must work harder to heat or cool the home. The strain the fans are under trying to accomplish this goal leads to the need for the early replacement of these components. 

Changing the Air Filter

Experts recommend changing the air filter monthly when using fiberglass filters, as they become dirty rapidly. On the other hand, pleated air filters last up to three months and trap particles other filters may miss. These serve as only two of several options when it comes to air filters for residential HVAC systems. 

Manufacturers provide recommendations based on average use. Homeowners should pay attention to that when they are reviewing replacement options. Consider the size and type of filter. The generic recommendations from the manufacturer should only serve as a guideline. Homeowners need to account for other factors that affect the filter’s lifespan. 


Pets shed, and their hair and dander can end up in your ventilation system. This can lead to odors and allergens that become trapped in the filter. Change the filter every two months to ensure it doesn’t become clogged and doesn’t unintentionally spread unpleasant odors throughout the home. 

Allergies and Asthma

Individuals suffering from allergies or asthma know how easily dust and debris can trigger an attack. The Allergy and Asthma Foundation of America explains indoor air quality often lags behind outdoor air quality. If anyone in the home has one of these common medical conditions, change the air filter every six weeks. Doing so helps to reduce the risk of an allergy or asthma attack and allows everyone in the home to breathe easily.  


Replace the air filters in your HVAC system every two months when you have young children at home. Doing so ensures the air quality remains at an optimal level and their developing bodies don’t take in unwanted particles. Furthermore, regularly changing the air filter helps to keep the home clean. 

Consider how you use the home before changing the air filter. A primary residence will require more frequent filter changes than a vacation property. If the HVAC system rarely operates, change the filters every six to 12 months. 

Many factors may lead to the need to change the air filter more often. The easiest way to determine whether the unit needs a new filter involves inspecting the filter every month. During this inspection, look for particle buildup. When the filter is covered in dirt and debris, change it. Ignore the recommended lifespan because the filter can no longer do its job. Replace it and know the system won’t have to work as hard to keep the home comfortable. 

How can a person know their filter has excess dirt and debris? Hold it up to a lamp. If little light passes through the filter, change it. The filter’s inability to let light pass is because of dirt and debris accumulating in its fibers. 

Changing the Air Filter

Most homeowners find they can change the air filter in their HVAC system quickly and easily. Purchase a filter, ensuring it is properly sized for the unit. Most filters have the size printed along one edge. If this information is missing, remove the old filter. Measure it and record the length, width, and depth. 

Determine which type of filter you would like to use in the system. Consider the following types as you make this selection. 

  • HEPA filters block small particles greater than 3 microns but don’t provide odor control. These cost-effective filters block tobacco and bacteria. Nevertheless, they fail to block finer particles like mold and gases. Before purchasing this type of filter, learn whether it will work with your system. High-rated HEPA filters only work in newer systems. 
  • Electrostatic filters come in both disposable and recyclable versions but don’t remove larger particles from the air. This type of filter attracts dust and allergens through electrostatic force, but individuals with respiratory issues should not use these filters. 
  • UV air filters significantly improve indoor air quality but are less cost-effective. They use UV rays to destroy microorganisms but don’t address fumes, smoke, and gas. Homeowners should know these filters create ozone in the home.
  • Washable filters are environmentally friendly but can develop mold and mildew if not properly cleaned and maintained. With proper care and maintenance, these filters last up to eight years. Expect to pay more at the time of purchase. 
  • Pleated air filters capture more particles, yet may decrease the efficiency of the system. As with washable filters, pleated air filters come with a higher price tag, but they don’t need to be replaced as often. The large air surface of these filters allows them to capture more dirt and debris, and individuals can recycle the filters when they replace them. 
  • Media air filters require little maintenance and must be installed by a professional. Fortunately, they only need replacement twice a year, making them a cost-effective solution. If odor control is a concern, choose another filter option. These filters aren’t of help with keeping odors at bay. 
  • Spun glass air filters come at a low cost but capture fewer particles. The use of these filters can bring about a negative airflow problem. 

Turn the system off. Use either the switch on the thermostat or the circuit breaker to ensure power is not going to the unit before removing the old filter. 

Determine where the filter is located and remove the cover or grille. Air handlers feature an access panel with screws. Remove the screws to access the filter. Return ducts, in contrast, feature latches. Open the grille by flipping each latch.

When removing the filter, pay close attention to its orientation. Replace the filter. The airflow arrows point into the unit when the filter is positioned correctly. Replace the grille or cover and turn the system on. 

Factors that Influence the Lifespan of the Filter

Several factors determine the lifespan of an HVAC air filter. Heating and cooling system usage plays a key role in how often a filter needs to be changed. Individuals who live in a mild climate find they don’t use their system around the clock. They only need it for a few hours every day. As a result, they only need a new air filter every few months. Some homeowners find they only replace the filter once a year when they live in this type of climate. In contrast, individuals who live in areas where the HVAC system runs continuously to keep the home comfortable need to change their filters frequently to ensure optimal system operation. 

The HVAC system in a small home pumps less air to provide the desired temperature. As a result, the filter in this system won’t need to be replaced as often. However, smaller systems come with smaller filters. Homeowners must monitor the filter in their HVAC system to learn how often they need to change it. A small filter in a small home may clog as easily as a filter used in the HVAC system of a larger home. 

Individuals want to breathe clean air in their homes. The HVAC system air filter determines whether they do. The filter works to trap dirt, debris, and other contaminants present in the air, with many of these contaminants making their way into the home from the outdoors. Homes in areas with poor outdoor air quality and those with pets that live indoors need frequent filter changes. 

Request Reminders

If you often forget to replace your air filter, schedule a reminder. Clean filters ensure dust and dirt don’t build up in the system. In contrast, a dirty filter impedes airflow while forcing the system to work harder to keep the home at a comfortable temperature. Furthermore, it may lead to expensive maintenance and repair bills. Dirty and clogged air filters often lead to the need for early replacement of the HVAC system. Regular filter changes help prevent these issues. 

AirNow Home Services offers a free air filter reminder service for clients. The client determines how often they wish to receive this reminder when subscribing to the service. Interval options include one month, four months, and six months. Speak with one of our technicians today to learn which interval is right for your home and system. We are happy to help you determine this and decide which filters best meet your needs. Our goal is to keep your system up and running at optimal levels at all times, and a clean filter goes a long way to making this happen. 

About AirNow Home Services:

AirNow Home Services works to do what is right for its clients, employees, and community. Our full-service air conditioning and heating team services and installs complete heating and cooling systems and assists clients with scheduled service checks, repairs of existing equipment, and more. Call (334) 835-8661 to schedule your appointment today.