Indoor air quality may not be something that crosses your mind until you start sneezing or the asthma or allergies of family members become irritated. Ensuring that your home’s HVAC system is properly cleaning your indoor air means using the correct filter. The MERV rating is a good place to start.
Dust, pollen, allergens, spores, and other microorganisms affect the quality of your indoor air each day. There are many different types of filters, each providing a different level of capture.
What is MERV rating?
HVAC air filters are rated by Minimum Efficiency Reporting Value, or MERV. This is a simple system for rating a filter’s ability to capture particles based on their size.
The rating is given based on a method of testing developed by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) and is helpful in determining which system will work best for you.
The MERV rating is set on a scale from 1 to 16. The number is assigned based on a filter’s ability to capture particles that range in size from 0.3 and 10 microns. For most homes and commercial buildings, filters with a MERV rating between 8 and 13 will sufficiently filtrate the air.
The air filter MERV rating indicates whether the filter will capture particles at a rate of between 84.9% to 90%. While that doesn’t sound like a huge difference, it is quite significant.
When shopping for a home air filter, most people will review a MERV 8 vs. MERV 11, or, for homes where allergies and asthma is a consideration, MERV 11 vs. MERV 13 may be more beneficial. Let’s break down what separates these filters and which one is right for you.
What does a MERV 8 filter capture?
A MERV 8 rated filter captures at least 84.9% of particles between the sizes of 0.3 and 10 microns. This is typically good enough to get the job done for the average home.
However, a MERV 8 filter captures less than 20% of particles smaller than 0.3 microns. That means things like pet dander, smoke, and some airborne bacteria are likely to get through a MERV 8 filter.
What does a MERV 11 filter capture?
A MERV 11 rated filter captures 85% or better of particles between the sizes of 0.3 and 10 microns. This may not seem like a significant difference compared to the MERV 8 filter, but a MERV 11 is also more capable of capturing between 65% and 79% of smaller particles.
For pet owners specifically, a MERV 8 vs. MERV 11 filter can make a noticeable difference.
The MERV 11 filter is better at capturing pet dander and bacteria from sneezes. It also provides additional protection against smoke, smog, or automobile exhaust fumes that may seep in from the garage.
What does a MERV 13 filter capture?
A MERV 13 rated filter captures 90% or better of particles between the sizes of 0.3 and 10 microns. The higher rated filter also captures up to 90 percent or better of smaller particles floating through the air.
The primary benefit when comparing a MERV 11 vs. MERV 13 filter is that the latter includes stronger protection against airborne bacteria and viruses that spread through droplets in the air.
Best MERV rating filter for home
The airborne pollutants in most homes will be captured in a filter with a MERV rating between 8 and 13. There are three ways to be more specific in determining your needs:
Evaluate your family’s lifestyle
If you have pets, opt for at least a MERV 11 filter. You’ll want a filter that captures the pet dander as well as loose hair. If there’s smoking in the home or allergies or asthma affect your family, go for a MERV 13.
Consider environmental factors
Living in Los Angeles comes with environmental challenges that those in Cumberland, Rhode Island don’t face. If you live in a smog city or otherwise poor air quality space, install a higher MERV rated filter in your home. Homeowners in rural areas are often shielded from pollutants with a MERV 8 filter.
Ask an expert
If you’re still unsure which filter MERV rating is best for your home, speak with an HVAC expert who can guide you to the right selection.
What MERV rating filter is right for my commercial property?
Strict building codes and an increase in foot traffic generally mean commercial properties should opt for a filter with a higher MERV rating. To protect the well-bring of your employees and patrons, install at least a MERV 13 rated filter in your commercial building.
MERV 13 filters help protect against the spread of bacteria, sneeze particles, smoke, and virus carrying germs. If your commercial space offers any type of health or medical services, speak with an HVAC specialist about your special needs.
In some instances, medical facilities benefit from filters with a 14 or 16 MERV rating. In surgical rooms and other spaces where absolute cleanliness is mandated, filters with a MERV rating of 17 to 20 are used.
Best MERV rating filter for viruses
Using a MERV rating 13 filter is best for shielding against virus spreading bacteria, but adding air quality solutions to your home should also be considered. An air filter alone is not a guarantee against airborne viruses like COVID-19, the flu, or the common cold.
For spaces where a higher indoor air quality is needed, consider adding a portable air purifier. Many of these devices can create cleaner air in a large space in a relatively short amount of time.
If you’re trying to fight mold and other allergens in your home, check out our guide on the best air purifiers for mold to see our picks for keeping your air clean.
Should I use the highest MERV rating filter available?
The heating and cooling system that supports your home needs an adequate amount of air flow to operate smoothly. Using the highest MERV rating filter in your home would restrict that air flow, making it difficult for your HVAC to function properly.
Filters with a MERV rating above 13 are woven together tightly to capture potentially harmful pollutants. That restrictiveness would make it hard for the air to circulate from your home into the unit.
Stick with a MERV 8 to 13 filter, depending on your family’s needs and environment, and begin using an indoor air quality monitor to help you determine if a separate air purifying system is needed.
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