Your HVAC system’s air filter plays a critical role in keeping your system operating efficiently. However, filters are often neglected, which can not only reduce your system’s efficiency but also cause additional repairs and cut away your system’s service life. Use this guide to learn why it’s important to change your HVAC system’s air filter, how often to change it, how to choose the right filter, and how to complete the change, whether your filter is located in the air handler or behind the grill for a return vent.

Effects of Neglected Filters

Air contains a wide variety of contaminants that can clog and damage your system if they’re allowed to flow into it. Air filters pull many of these contaminants from the air as it enters the system. However, that means that they will eventually clog, restricting the airflow the system gets.

The restricted airflow into your system will initially reduce your system’s heating and cooling efficiency, increasing your energy costs. Less airflow through your system also prevents the system from transferring the amount of heat it’s intended to during a normal cycle. For a traditional heating system, this means trapping heat inside the system, potentially causing it to overheat. Conversely, this lack of adequate airflow will cause your air conditioner or heat pump to freeze up. In both cases, the airflow restriction can damage internal components, causing preventable repairs and shorter service life.

How Often to Change Your Filters

There is not a single answer that’s always correct for how often you should change your air filter. However, when you understand the variables involved, it’s easier to arrive at the right answer for your home, which may not be the same as a neighbor’s.

It starts with the general recommendation for how often to replace your filter based on its thickness. The common 1- and 2-inch filters generally last 30 to 90 days, and for systems that use thicker filter media, 3- and 4-inch filters may last six to nine months, and 5- and 6-inch filters will last nine months to a year.

However, your home’s indoor air quality may shorten your filter’s service life. When more contaminants are floating around in your home’s air, the filter will clog faster. While you may largely have decent air quality most of the time, certain times of the year and some household projects may produce more contaminants, lowering your air quality.

To replace your air filter frequently enough, we recommend checking it monthly. During this check, simply look to see how much dirt is on the intake side of the filter. If your filter is visibly dirty or has dirt or hair clumped on the surface, then it’s likely time to change it.

Choosing The Right Filter

Keep in mind that not all furnace filters are created the same way, and getting the wrong filter can cause as many problems as neglecting them. Start by making sure you have the right size. Do not attempt to put in a thicker filter just because they tend to last longer, it’s important to only use the size filter intended for your system.

Next, consider the filter’s rating, which is known as the MERV rating. The higher the rating, the more contaminants of a smaller size it’ll pull from the air. However, this also means that the system must create stronger suction to get sufficient airflow through the filter. Make sure to review your owner’s manual to see what MERV rating your system can handle. If you don’t have your owner’s manual, or if it doesn’t indicate the filter size, ask your HVAC technician during your next maintenance visit to get their recommendation on the proper filter for your system.

Replacing Filter in Air Handler

Not all systems keep their filters in the same place. One common place is in or near the air handler cabinet. Before pulling your filter out, you’ll want to turn off the power to your HVAC unit. You can start by going to your thermostat and switching it to the off position. If you want even more safety, go to your breaker box and flip the breaker off for your HVAC system.

Next, open the door and clean it with a microfiber cloth. Some doors may simply close over the filter, while others will snap into place. Slide out the old filter and immediately put it in a garbage bag.

Now check the filter type to make sure that you’re replacing it with one of the same size and a similar rating. Take the new filter and make sure that you slide it in facing the proper direction. There are arrows on the edge of the filter that indicate which way the air should flow through the filter. The arrow should point away from where the air is coming from and toward your system. Close the door and turn the power to the system back on.

Replacing Filter In Return Air Duct

Replacing a filter that’s housed in the return duct is similar to replacing one that’s housed in the air handler cabinet. Start by turning off the system at the thermostat or at the circuit breaker. Locate your return air duct, keeping in mind that your home may have more than one. Return ducts that house an air filter will be rectangular or square, the same shape as the filter it houses. Some homes have this return duct on the ceiling, while others have it on a wall.

Once you’ve located the duct, you’ll need a screwdriver to remove the vent cover. Some models come off completely, while others simply swing out of the way. Once you have it open, remove the old filter and immediately put it in a garbage bag to prevent dirt and contaminants from making a mess. You can clean the dust from between the slots in the grill with a screwdriver covered in a soft cloth or by using a vacuum with a brush attachment.

Now grab the new filter, making sure that it is the same size as the one you just removed. Point the arrows indicating airflow direction away from you, and put it in the housing for the return vent. Now close the cover, tighten the screws, and then turn the power back on.

Usage Tips for Your Air Filter

There are some things you can do that will cut the life of your filter, as well as some ways to extend it. First, avoid putting anything on your filter, including baking soda or essential oils. These can cause the air filter to clog more quickly.

Next, give your filter a boost by checking it monthly and gently vacuuming off the surface contaminants. Be careful that you only vacuum the intake side of the filter to prevent drawing more contaminants into the filter, causing it to clog more quickly. This monthly check will also help you determine the proper replacement schedule for your home.

People around Mesa turn to Honest Air Conditioning to keep their homes comfortable throughout the year. Our expert technicians provide heating and cooling installation, maintenance and repair together with indoor air quality solutions. Call to schedule your system’s maintenance visit to ensure you’re getting the most from your system and reducing the risk of preventable repairs.