Understanding Your Air Filter Configuration

The HVAC system is often the most important appliance for homeowners. To ensure that your system functions at its best and has a long life, regular maintenance is required.

The number one action a home owner can take is ensuring that filters are changed when needed. Clogged filters cause undue strain on the system and can also increase your monthly energy bill.

Before you can change your filters, you will want to get familiar with where your home’s filters are located, how many you have, and size and type they are. Here are some guidelines to help you determine what type of system you have. If you have any doubts, you can always refer to your owner’s manual. If you do not have a manual, one can always be obtained from your HVAC manufacturer.

Most central HVAC systems will handle its filtration in one of the following two ways:

Air Return Filtration

Many systems have filters that are easily accessed in the home. If you have seen any air vents or grilles in your walls, ceiling or floor – There is a good chance this is the type of system you have. Unlatch your grille for access to the air filter.

If you have this type of setup then you may have more than one filter. Be sure to check all rooms in your home and note all filter locations.

All your air filters should be changed when needed. Do note that each filter may have its own independent schedule for when it needs to be changed based on its location in your home. Not all filters get dirty at the same rate or at the same time.

In-Unit Filtration

If you do not have any air vent grilles in your home, then you probably have an In-Unit filter. Your air filter will be located where your HVAC air handler or furnace is located. These are often located in a closet, attic, crawlspace, or basement. Your filter will likely be behind a removable panel or flap.

If you have a multi-stage filtration unit, please see your owner’s manual for filter details.


Hopefully you have determined how filtration is handled with your unit, you are prepared to perform the most common maintenance task for maximizing your home’s efficiency and air quality.a

OK, Now what?

Find dirty filters? If you found filthy air filters when locating your filters, it may be a great time to change them. Head on over to Changing Air Filters 101 to take the next step.

Are you left with more questions about your specific HVAC system? You can always find answers in your owner’s manual.