technical article

What Is The Best MERV Rating For Furnace Filters


One of the best things you can do is replace your furnace filter on a regular basis. Whether you head to your local big box store and look at your selection, or do a little research online, you'll be faced with something called a MERV filter. What is a MERV rating and why does it matter?


What is a MERV?

MERV stands for Minimum Efficiency Reporting Value. It tells you how effective your air filter is compared with others on the market.


You'll find MERV ratings range from 1 to 16. The higher the MERV rating on a filter, the fewer dust particles and contaminants can pass through it. The American Society of Heating, Refrigerating, and Air Conditioning Engineers designed the MERV rating to show a filter's worst possible performance at removing particles ranging from 0.3 to 10 microns in size. Common particles at this size range from pollen, dust mites, carpet fibers, mold, pet dander, bacteria, and tobacco smoke.


In a home setting, you'll likely find MERV ratings of 7 to 12 can do the job efficiently. In hospital or clean facilities, the MERV ratings will move to 13 to 16.


Higher Isn't Better

You might think that increasing the rating automatically would be better for your home, but that's not always the case. The higher the MERV rating, the smaller the pores are for air to flow through the HVAC filter. This can create more resistance in airflow than your system was designed to manage, thus making your HVAC system more inefficient. That means reducing the air flow in your system can actually worsen the air quality inside your home. It can also be a cause of damage to your overall furnace and air conditioner.


The best way to avoid problems is to find out what your manufacturer recommends. Each furnace comes with a recommended list of MERV ratings that still allow maximum airflow to your system while removing the most harmful of particles from the air.


It's also a better practice to change out your filters frequently. Filters with higher MERV ratings need to be changed more frequently to avoid restricted airflow that can cause your system to work inefficiency or possibly even damage it.