What do air filters do, and how does an air filter work? The idea seems pretty simple, but purifying the air can be a somewhat complex task considering there are 60+ sources of indoor air pollution. Not to mention the hundreds of products that can release volatile organic compounds (VOCs) into the air.

An air filter clearly serves a purpose, but does every home need one? The guide below will provide information about what air filters are and why they are used to better explain why every home with an HVAC system can benefit from having them.

What is an Air Filter?

Let’s start with the basics by defining what an air filter is. An air filter is essentially a screen that fits into a compartment of the HVAC system to clean the air as it circulates through a home.

Air filters are an aftermarket product with a longevity that typically spans 1-6 months for disposable filters. Washable air filters can last up to five years.

The Purpose of an Air Filter

So, what are air filters for? What does an air filter do in your house once it’s installed? The primary air filter purpose is cleaning the air inside so it’s healthier to breathe. You may not realize that many homes have air quality that is worse than outside, and your home could be one of them. If you don’t have proper ventilation and air filters for purification contaminants can build up inside.

Air filters are also a part of the overall HVAC system. They serve as a first line of defense that protect HVAC components from contaminants.

What air filters are made of can influence whether they have a specialized purpose. For example, air filters with carbon are particularly good at removing odors from the air.

How Do Air Filters Work?

Understanding how air filters work can help you decide which filter is best for a specific purpose. All air filters work in a similar fashion:

• Air passes through the filter screen.
• As the air passes through, the filter media (material) catches particulate matter such as pollen, dust, pet dander, dirt and allergens. Some types of air filters can even remove bacteria and viruses from the air.
• Every second as air passes through the filter media contaminants build up. Eventually, the filter gets too clogged and airflow is reduced.
• Eventually, the filter gets too clogged and airflow is reduced.
• The air filter is then replaced, and the process continues.

Where air filters differ most is the media that is used. Filter media quality and quantity influences the size of air particles that can be captured, how they are captured and airflow through the system.

MERV Ratings - Better Purification, Restricted Airflow

People put a lot of emphasis on the Minimum Efficiency Reporting Value (MERV). The MERV rating is important beyond indicating how well the filter purifies the air. It can also affect airflow, which has a negative impact on the HVAC equipment, energy efficiency and your comfort.

MERV ratings range from 1 (least efficient) to 20 (most efficient). Air filters with a MERV rating of 14 or higher capture more particulates but they also restrict the airflow more and get clogged faster.

Read More: All About MERV Ratings

Are Air Filters Necessary?

If a primary air filter function is to clean the air, is it necessary to use one in a home with good air quality? Do air filters make a difference if the air is healthy? Do allergen furnace filters work well enough to eliminate the use of an air purifier?

The short answer is yes, because air filters don’t just clean the air effectively. They also protect your HVAC equipment.

Air Filters Keep Debris Out of the HVAC Equipment

Air filters keep debris and air particles out of sensitive components. Two places where dust and dirt could accumulate are the duct system and air handler. The debris will build up over time creating a variety of issues, along with polluting the air inside.

Air Filters Improve Efficiency and Reduce Equipment Wear

Do you like wasting energy and paying more than you need to heat and cool your home? If the answer is no, then you’ll want to replace your air filters regularly.

With less dirt and debris in the system, HVAC equipment runs more efficiently. The opposite is true if you have no air filter or the air filter is so dirty it’s restricting airflow. When that happens parts like the fan motor will have to work harder, which means more electricity is consumed. The fan motor is also more likely to need repair.

Even if you’re lucky enough to have great air quality inside without an air filter, your HVAC equipment still needs that layer of protection to work efficiently.

Find the best air filters for your home - search by MERV rating, media type or size