If you’ve taken a look at your HVAC filters, you have probably noticed that each one has a MERV rating. MERV stands for “minimum efficiency reporting value” and it has some important implications.
The filter’s MERV rating indicates how effectively the filter removes particles from the air as it passes through. The higher the MERV rating, the tinier particles it can catch, leaving you with cleaner, easier to breathe air.
There is a downside to using a filter with a high MERV rating, however. A filter with a high MERV rating will feature a denser filtration medium. It takes more force to push air through dense filtration medium. So, using a filter with a rating at the high end of the MERV scale puts significant strain on your HVAC system.
Finding the Best MERV Rating for Your Home
If you replace your HVAC filter with one that has an excessively high rating, your system will struggle to push air through the system. It has a similar effect running with an old, dusty filter, and your system will not run efficiently. As your system struggles to push air, accelerates the wear on the system’s components. This extra strain can lead to frequent expensive repairs.
To determine the best MERV rating for your home and HVAC system, start with the owner’s manual. Look in the manual for the listed maximum MERV rating. Using a filter with a value higher than the recommended limit immediately affects the system’s efficiency and will ultimately lead to costly future repairs.
Once you have determined the recommended MERV ratings for your system by checking the owner’s manual, it is time to consider other factors. If you or someone in your family suffers from asthma or allergies, you should consider selecting a filter with a MERV rating on the higher end of the recommended rating range. Also, if you have shedding pets or an abnormally dusty home, you’ll need to choose a higher rated filter.
The Numbers Explained
Filter MERV ratings range from 1 to 20. Most residential HVAC filters fall in the 1-4 range. However, it isn’t uncommon for some homeowners to use filters rated as high as 8 if they have special circumstances.
Filters with different MERV ratings are best suited for different circumstances. Here is a basic guide that covers the various MERV rating ranges and their capabilities.
MERV 1-4
Filters that fall into this rating range catch mostly large particles. Used primarily for residential use, these filters are effective at filtering dust, carpet fibers, insects and insect parts, and pollen.
MERV 5-8
Used in some residences, as well as most commercial and industrial settings, filters in this range capture smaller particles including mold spores, pet dander, fine dust, and even aerosol spray particles.
MERV 9-12
Filters in this range are rarely suitable for residential use. They are more commonly used for certain commercial buildings and some hospital settings. These filters have a dense filtration medium capable of capturing fumes from vehicle emissions, welding fumes, some larger bacteria, and dangerous lead dust.
MERV 13-16
Useful in hospital surgical centers and other places where heavy-duty filtration is necessary, filters in this range collect tiny smoke particles, various strains of bacteria, and fine particles emitted when a person sneezes.
MERV 17-20
At the highest end of the MERV scale, filters within this range are used in “clean rooms.” Also, utilized in locations where pharmaceuticals and sensitive electronics are manufactured, these filters remove carbon dust, the tiniest smoke particles, and even dangerous viruses.
While you won’t need filters at the highest end of the MERV rating scale, you do benefit from them. Whenever you take medication or use your cell phone you are enjoying a product whose development and manufacturing are dependent on high MERV filtration.
If you need help finding the appropriate filter for your home HVAC system, contact your local HVAC professionals for recommendations.