Next time you look at your air filters, perhaps in the company of your local HVAC professional, you may see something called a MERV rating on each of them. What is a MERV rating? How does it affect your home?
MERV is an acronym that stands for Minimum Efficiency Reporting Value. It’s a numeric value that indicates how effective your air filter is at doing just that—filtering air. The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) created the MERV scale to represent an air filter’s performance.
Read on to learn more about MERV ratings and how they affect the indoor air quality of your home.
How Do MERV Ratings Work?
The MERV rating system works on a scale of 1 to 20, with 20 being the most effective air filtration. Let’s break the scale down a little further.
- A MERV rating between 1 and 3 only captures up to 20 percent of the larger air particles in your home, measuring between 3 and 10 microns. Think pollen, dust, animal dander, and bits of hair.
- Filters with a rating of 4 are often made of fiberglass. These can catch dust mites along with the larger particles mentioned above.
- A rating between 5 and 7 is often seen on pleated cotton filters. A cotton filter can remove up to 70 percent of large particles from the air in your home. It’s important to note that you will have to change these filters monthly.
- Filters with a MERV rating of 8 to 10 remove up to 85 percent of large particles, between 3 and 10 microns, as well as about half of the small particles floating around. Say goodbye to bacteria and residual smoke!
- You’ll often see a MERV rating between 9 and 16 on air purifiers meant for the whole home. An HVAC professional can install a purifier to supplement your existing system. These purifiers are often used in hospitals to catch bacteria and virus particles floating in the air.
- MERV ratings between 17 and 20 are used almost exclusively in medical settings. These filters can get rid of particles less than 0.3 microns in size.
What’s the Best Rating for My Home?
While you may think you need the highest MERV rating possible for your home after reading the above breakdown, you really need to consider the logistics. The higher the MERV rating number, the more restricted the airflow in your home will be—your home’s air has a lot of particles floating around, after all.
Think about air filtration like sifting flour; it takes much longer to sift flour through a fine sieve than through a colander. The higher the MERV rating, the longer that filter will take to sift out every single particle. And keep in mind that filters with higher MERV ratings also need to be changed more often in order to keep your system clean and functional.
If you’re not in a hospital setting, there’s no immediate need for a filter with a MERV rating of 20. Many HVAC professionals recommend 13 as the magic number for residential systems. However, the ideal rating also depends on what your current system can handle. Talk to your local HVAC specialist about the best rating for your existing unit.
If you want extra filtration without upgrading your entire HVAC system, consider investing in a HEPA filter for the home. HEPA filters are equivalent to a MERV rating of 16 because they filter out particles as small as 0.3 microns.
Other Considerations
As you decide which air filter will work best with your current HVAC system to clean your indoor air, keep these other elements in mind.
Energy Usage
Remember, the higher your air filter’s MERV rating, the harder it will have to work to filter out contaminants. The pores in the filter are much smaller, which can have an effect on airflow. An air filter with a MERV rating of 16 will use more energy than one with a rating of 12.
If nobody in your household has severe allergies or a compromised immune system, there’s not much reason to have a hospital-grade air filter in your home. Most residential HVAC systems work well with filters rated between 8 and 13 on the MERV scale. Staying in this sweet spot will allow for good airflow throughout the home while filtering out the most common contaminants.
Overall Air Quality
If you opt for a filter with a high MERV rating but forget to change it every month, your home’s indoor air quality can actually suffer. That filter will get clogged quickly due to the amount of tiny particles it’s trying to filter out. And if you don’t change it, those particles will continue floating around your home.
However, some households do benefit from filters with a higher MERV rating. If you or someone in your home has a weak immune system, you could benefit from a filter that will get rid of bacteria and virus particles in the air.
Your Unique HVAC System
When making any choice that affects your home’s indoor air, consult with an HVAC professional for advice. The specialist who performs your AC installation service can recommend the right MERV rating for your home.
It’s crucial for your air filter’s rating to match your HVAC unit’s recommendation. If your unit works best with filters rated between 8 and 13 but you install a filter with a rating of 16, your home’s airflow can be negatively impacted.
In addition, think about the dimensions of the filter itself. Some custom-built HVAC systems require filters with a unique size. Take thorough measurements of your system and existing filters before buying new ones.
Next time you change your air filters, think more about the MERV rating printed on them. Is the rating adequate for your home? Now that you know what MERV ratings are and how they affect your home, you can make educated decisions alongside your local HVAC professional about your home’s air quality.
Still have questions? First Goal Heating and Cooling employs a team of friendly and seasoned professionals who can answer them for you. Contact us with any questions about the right MERV rating for your home, and we’ll work with you to find the best solution.
