How Often Should My HVAC Filters Be Replaced?

How Often Should My HVAC Filters Be Replaced?

It is common knowledge that you should replace the HVAC filters regularly. But how long should this interval be? More importantly, why is it necessary to keep replacing the air filters? Is it really needed, or is it a marketing gimmick to make you spend money on the filters?

In this post, we’ll answer all of these questions in more. So, let’s begin-

What are HVAC Filters?

To understand why technicians lecture you about replacing HVAC filters every time they visit your home, it is critical to know what these filters are.

Made from pleated paper orfiberglass, HVAC filters or air filters are installed at particular locations within the return air duct of the HVAC system.

The primary function of these filters is to function as a barrier for contaminants from getting into the HVAC unit or circulating indoors. The filters can block dirt, dust, mold, bacteria, viruses, lint, pet hair, and more.

So, when your technician recommends replacing air filters at regular intervals, it is no marketing gimmick. It is absolutely necessary to maintain indoor air quality.

How Often Should You Replace the HVAC Filters?

Unfortunately, there’s no single answer to this question. The general rule of thumb is to replace them according to their thickness and efficiency, although various factors can impact this timeline.

Some of the most important ones are as follows-

Type of Filter

As mentioned above, there are two common types of air filters- pleated paper and fiberglass. While both are disposable, there are some differences between the two.

For instance, pleated filters are more expensive but more effective in trapping contaminants. Depending on usage, a pleated filter should generally be replaced after 30 days, if it is only 1” thick.

Fiberglass filters are cheaper but less efficient. As a result, they should be replaced every 30 days, at the maximum. In some circumstances, they will need replaced more often. Beeson Mechanical Service does not recommend every using fiberglass filters, for any application.

Size of Home

The size of your home is also vital in deciding how frequently you should replace HVAC filters. Larger homes require more air, so the filters can get dirtier sooner. As a result, they should be replaced more frequently.

But if your home is smaller, it needs a lesser amount of air through the air conditioner or furnace, leading to less frequent replacements.

Air Quality

Even the outdoor air quality has to be taken into consideration.

Generally, in bigger cities, the pollutants in the air, like dust, smoke, etc., are on the higher end. Due to this, the filters get clogged faster and require frequent replacements.


Sensitivity to indoor pollutants such as dust mite, mold, pollen, and dander is higher in children. Therefore, if you have young children at home, it’d be wise to get the filters replaced at a more frequent interval.

It is generally said that homes with higher occupancy decrease the lifespan of the air filters, and ones with lower occupancy increase the filter’s lifespan.


If any of the family members have allergies, the symptoms can be reduced by using good-quality filters and replacing them more frequently.

Excess pet dander, dust, and other allergens can worsen allergy symptoms like sneezing, runny nose, and coughing.


Even furry pets impact indoor air quality as they keep releasing dander and hair. Moreover, they also attract pollen, dirt, mold, etc., from outside.

If you have pet/s, you should check the HVAC filters every 30 days and replace them when they’re dirty.

Improve Indoor Air Quality by Regularly Replacing HVAC Filters

As can be seen, the HVAC filters directly impact indoor air quality, and several factors influence their replacement frequency.

So, take these factors into consideration to decide when you should replace the filters. If it seems too confusing, ask your HVAC technician at Beeson Mechanical Service at 317-535-9338, to discuss further.