When replacing an AC filter, consider the filter’s MERV rating. The Minimum Efficiency Reporting Values (MERV) rating is used to determine the filtering efficiency of an AC filter. Filters with higher MERV ratings can trap particles as small as 0.1 to 0.3 microns, delivering better air quality. However, deciding on the best MERV rating for your home can be challenging. Here are a few tips to help you make an informed decision.
Types of AC Filters and Their MERV Ratings
AC filters are designed to remove airborne pollutants to improve air quality. The types of AC filters have their own pros and cons. You’ll have to consider different factors when choosing the right filter for your home. One of the key factors is the MERV rating.
Standard AC filters—typically made out of spun glass or similar materials—are designed to remove larger contaminants from the air. They have a MERV rating ranging from 1 to 4, indicating their ability to remove smaller contaminants from the air is low. These AC filters are typically used in homes or units with minimum filtration needs.
A pleated filter that contains folded fabric—such as polyester or cotton—comes with a MERV rating higher than 5. These AC filters can effectively remove smaller particles, including pet dander, pollen, and mold spores.
Electrostatic and HEPA (High-Efficiency Particulate Air) filters come with MERV ratings of 8 or higher. These filters can capture smaller particles, including harmful microorganisms. Although these filters are highly efficient in filtering contaminants, they are generally used more in commercial settings, labs, or hospitals with high filtration requirements.
What MERV Rating Should I Use?
The American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) recommends homeowners use AC filters with MERV ratings of 8 to 13. Filters with these ratings do not restrict airflow or overload the AC system. Instead, they can improve indoor air quality by trapping around 80% of the contaminants in the air, including fine dust particles and allergens. These filters can also provide a comfortable indoor environment for people with allergies.
Filters with MERV ratings 8 to 13 can also improve the system’s energy efficiency by preventing dust and debris from entering the system and affecting the function of its components. There are certain factors homeowners should consider when it comes to choosing an AC filter with a high MERV rating. The first thing you should consider is your system’s capability of handling the MERV rating.
Generally, filters with higher MERVs are thicker, which may be great for particle filtering but not the right fit for the filter compartment or slot in your HVAC unit. Unfortunately, there is no standard filter size or thickness for all HVAC units, so you should check your HVAC filter sizing requirements in the owner’s manual before purchasing a filter.
Even though filters with higher MERV ratings can provide better filtration, they may require your system to consume more energy to meet the temperature requirements. The small holes in these high-efficiency filters can restrict airflow, making the system struggle to pass air. This can put the unit under undue stress and cause its components to wear faster. You can learn more about MERV rating to make an informed decision on what type of filter to install in your AC.
Photo by Max Rahubovskiy
