Air filters are an essential part of your AC system. They are the only thing keeping nasty air pollutants and other particles out of your home. That being said, air filters need to be changed periodically in most cases (permanent filters excluded).

 

Failing to do so can cause all kinds of issues, starting with a decrease in airflow. However, not all air filters are created equal. Here’s all you need to know. 

How to Choose the Right Air Filter? 

There are many factors that impact the efficiency and quality of air filters. However, we’ll first need to understand the most basic variables of selecting the right filter for your home AC system and to start things off, you need to know the size of the filter that fits your AC system. 

Different AC models run different sizes of filters. Also, keep in mind that the thickness of the filter is something to think about, not just the size of the filtration medium. You should be able to find all the necessary information in your AC system’s manual. 

Different Types of Filters 

 

As it turns out, there are many ways to filter air. AC filter manufacturers have diversified the market of air filters to a point where you need to sit down and compare the pros and cons of the dozens of available models. That being said, the first main classification puts filters into two categories — disposable and permanent. 

 

• Disposable Air Filters - Disposable air filters are meant to be used for a set period of time. Once that period is up, the filter should be thrown away and replaced by a new one. Disposable filters come with filtration media that you can’t clean. 

• Permanent Air Filters - Permanent air filters also get dirty over time. However, instead of throwing them out, you can just pull them out, wash them, and put them back. These are magnitudes more expensive than disposable filters, for obvious reasons. 

Different Types of Filtration Media 

Filtration media is what defines how effective an air filter is. As far as disposable air filters go, you’ll find fiberglass and pleated filters. Fiberglass filters are meant to stop the larger particles from passing through. 

Things such as large dust particles, lint, hair, and similar debris will get caught in the fiberglass membrane. There are also electrostatic fiberglass filters that feature charged fibers that use the electrostatic effect to draw in particles of dust and other debris. 

Pleated filters are several levels above fiberglass ones. Air filtration engineers from Filter Buy note that pleated filters are capable of capturing big particles, but also tiny microscopic ones. With pleated filters, you’ll be removing all kinds of spores, allergens, and other often invisible pollutants from the air that’s being fed into the system. Granted, pleated filters are more expensive on average, but they are worth the investment. 

MERV and HEPA - Understanding Different Rating Systems 

Every air filter you’ll find out there has to meet certain filtration standards before it’s cleared for sale. The two most popular acronyms you’ll run into are MERV and HEPA. 

MERV - Minimum Efficiency Reporting Value is a scale of particle filtration efficiency developed by ASHRAE. Filters built in compliance with MERV standards will feature a MERV rating that comes in the form of a number. These go from 1 to 16 where the higher value means that the filter is more efficient. A good rule of thumb is to look for filters that feature a MERV rating greater than 10. 

That being said, MERV-rated filters are designed to remove particles that are anywhere from 3.0 to 10.0 microns in size. 

HEPA - High-Efficiency Particulate Air filter or HEPA isn’t necessarily a filtration standard as much as it is a defined type of filter. The idea behind HEPA filters is to remove 99.97% of all particles that are 0.3 microns in size. Particles of this particular size present the highest danger as they are able to penetrate deeper than particles larger or smaller in size. 

This type of filter is generally recommended for those who suffer from asthma or people who are highly allergic to dust or any other allergens. 

Whether you’ll go for permanent or disposable air filters is a matter of personal preference. Pleated disposable filters are arguably the most efficient ones, but they also cost the most. Electrostatic permanent filters are a great middle-ground solution that is costly but offers a long use life. It’s up to you to figure out which filter best matches your needs and preferences.