The air filter in your home’s heating and cooling system is used to clean the air before it is distributed throughout the house. Neglecting to replace your filter on a regular basis leads to poor air quality and can cause your system to work harder than necessary. Using an air filter with an improper MERV rating can also be a factor. It’s not a complicated process to choose the proper filter. You simply need to know your needs and what to look for. 

What are MERV ratings?

MERV stands for Minimum Efficiency Rating Value and comes with a range of 1-16. The lower the number on the MERV scale, the lower the filtering efficiency will be. The higher-rated filters are capable of trapping smaller particles than the lower numbered filters. We can view the MERV values through four tiers. The American Society of Heating, Refrigeration and Air Conditioner Engineers (ASHRAE) uses particle size to categorize the MERV values. The largest particles are 3-10 microns, followed by 1-3 microns, and the smallest particles are .03-1 microns.

MERV Rating 1-4

Air filters with a MERV value of 1-4 will trap less than 20% of particles 3.0-10.0 microns in size. Particles in the size range include pollen, carpet fibers, and dust mites. Simply put, these filters will have the least restriction to the airflow and will trap the lowest volume of particles. 

MERV Rating 5-8

Filters in the 5-8 MERV value range are also able to trap particles with 3.0-10.0 microns in size, but they are more efficient in doing so. A MERV 5 filter will trap up to 34%, MERV 6 will stop 35-49%, MERV 7 will prevent up to 69%, and MERV 8 will catch up to 85% of particles. These filters are slightly more restrictive than the MERV 1-4 filters and have the ability to catch mold spores and some pet dander along with dust and pollen. 

MERV Rating 9-12

This range of MERV values can begin trapping particles in the 1.0-3.0 micron range. In this range, we start to see pet dander, lung-damaging dust, and auto-emissions trapped. Filters in this range can trap more than 85% of the particles sized 3.0-10.0 microns. A MERV 9 will trap less than 50% of particles sized 1.0-3.0 microns, MERV 10 will stop up to 64%, MERV 11 will get up to 79%, and MERV 12 is capable of catching up to 89%.

MERV Rating 13-16

Filters with a MERV 13-16 value are the most restrictive and can trap the smallest particles like bacteria, tobacco smoke, and burning wood. These particles are in the .03-1.0 micron group. MERV 13-16 filters are capable of trapping 90% or more of particles in the 1.0-10.0 micron range. MERV 13 will prevent less than 75% of the 0.3-1.0 micron particles from passing through, MERV 14 will get up to 84%, MERV 15 up to 94% and MERV 16 can trap 95% or more of the smallest particles. 

How to choose an air filter with the right MERV rating?

The math would seem to tell you that if you want to have the best air quality you should buy a filter in the MERV 13-16 category and call it a day. However, more is not always better when it comes to MERV ratings for a residential furnace filter. There are a number of things to consider before selecting a filter for your heating and cooling system. 

Determine your air filter needs

A home with no pets, smoke, or allergies will do just fine with a MERV value of 1-7. If you have pets or someone in your home has significant allergy problems, you may want to consider a higher MERV value, between 8-10. Homes with smokers or a wood-burning fireplace should have a filter in the MERV 11-13. MERV values above 13 are generally for hospitals, manufacturing plants, and other environments that have high air quality requirements. 

Consider the air filter cost and replacement frequency

The cost of an air filter for your home heating and cooling system will increase with the MERV value. If you don’t truly need a higher MERV filter do yourself a favor and select the cheaper option. A filter should be replaced every 1-3 months. If you use a higher MERV rating that traps more particles, you may have to change the filter more often. A clogged filter can cause serious complications for your heating and cooling system as the system will be required to work harder to circulate the air, and the air quality will drop. 

Choose the right filter size

Each system requires a unique size of air filter. There are a wide variety of width, height, and depth options. This information will be printed on your existing air filter. Be sure to know what you need before purchasing heading to your home improvement store. Your future self will thank you! 

Contact Wyckoff for Regular Furnace Maintenance

You’re now equipped to monitor your air filter and change it on a regular basis with the right MERV value for your home and family. Heating and cooling systems require more than a simple DIY treatment. At Wyckoff Heating & Cooling, we offer affordable inspections on a bi-annual basis. When you sign up for our Peace of Mind service plan, you will get a thorough inspection of your heating and cooling system from one of our certified technicians twice a year. Each plan comes with discounts on parts, labor, and other services. Sign up the Peace of Mind plan today!