Does a MERV 13 air filter over a MERV 8 filter make any difference? The most notable difference between these two filters is the cost to most consumers. So, what’s so great about MERV 13 filters? What justifies the cost? An air filter is just an air filter, right? Wrong.
In a nutshell, MERV 13 filters provide the best air quality a home can have because they are the highest-rated air filters for residential use. MERV 13 filters can block up to 98% of contaminants in the air and can trap microscopic particles between 0.3 and 1.0 microns in size. Highly-efficient MERV 13 filters effectively filter airborne illnesses, air pollution, and smoke from wildfires. Yet, MERV 13 filters are not recommended for every household.
What is a MERV rating?
A MERV (minimum efficiency reporting value) rating represents an air filter’s ability to trap airborne contaminants. The MERV scale was developed by ASHRAE (The American Society of Heating, Refrigerating and Air Conditioning Engineers) and reflects a filter’s worst possible performance.
An air filter MERV rating scale ranges from 1 to 20. Filters with higher ratings are denser and more effective at trapping particles than filters with lower ratings. The MERV rating indicates the number of contaminants an air filter can trap. The rating also incorporates the size of contaminants. In particular, the MERV rating expresses an air filter’s ability to trap airborne particles between 0.3 and 10 microns. One micron is equal to 0.00003937 inches or 0.001 millimeters. To put that into perspective, a grain of table salt is approximately 120 microns.
Although the MERV scale is broad, specific rankings are better suited for residences than others. Air filters rated between 1 and 7 provide low-level filtration and are used primarily in industrial settings. Air filters rated between 14 and 20 provide high-level filtration and are used primarily in healthcare settings. The most appropriate air filters for residences fall near the middle of the scale, between MERV 8 and 13.
What Does MERV 13 Filter Out?
MERV 13 filters are highly efficient at filtering out various particles between 0.3 and 10 microns. In other words, MERV 13 filters can capture more contaminants and smaller particles than lower-rated filters for residential use.
According to the EPA, MERV 13 filters boast 90% efficiency capturing particles between 3.0 and 10 microns, 85% efficiency capturing particles between 1.0 and 3.0 microns, and 50% efficiency capturing particles between 0.3 and 1.0 microns.
In addition to filtering the usual dust, dust mites, lint, and pollen that other filters trap, MERV 13 filters can filter out smoke, smog, microscopic allergens, viruses, bacteria, mold, exhaust fumes, and pet dander from multiple pets.
Despite the numerous qualifications of MERV 13 filters, highly-efficient filters are not necessary for most households. Filters within the 11 to 12 range also capture fine particles between 0.3 and 1.0 microns but to a lesser degree. Filters in the 8 to 10 range cannot capture fine particles, but they are pretty good at capturing larger particles. In many cases, filters between 8 and 12 are sufficient for filtering contaminants from the home’s air. For example, a MERV 8 filter provides ample filtration in a house with no pets, little outdoor pollution, and no residents with health concerns.
Highly-efficient filters can also tax heating and air conditioner systems because of reduced airflow due to the filters’ density. Airflow reduction can cause the system to run longer, the blower to work harder, and the compressor to overheat. Homeowners should consult their owner’s manual or an HVAC professional before upgrading to a high-efficiency filter to be sure it is compatible.
What's the Difference Between MERV 11 and MERV 13?
The critical difference between MERV 11 and MERV 13 is that MERV 13 filters better trap fine particles. MERV 13 filters trap 50% of fine particles versus MERV 11 filters that trap 20%. In particular, MERV 13 filters can trap bacteria, viruses, smoke, and microscopic allergens.
Even so, MERV 11 filters are more popular than MERV 13. They trap a wide variety and large quantities of contaminants that are more than sufficient for most households. MERV 11 filters are 85% efficient at trapping larger particles, only a 5% difference compared to MERV 13 filters. MERV 11 filters are ideal for houses in moderately populated areas, pet owners, and people with mild allergies.
MERV 13 filters are the highest-grade air filters for residential use. Higher-rated filters are primarily used in healthcare settings where pristine air is of the utmost importance. Most homes do not require such a high level of air quality. MERV 13 filters are suited for houses in densely populated areas with high levels of air pollution, immunocompromised people, and people with severe allergies and asthma.
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POLLEN |
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DUST / LINT |
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DUST MITES |
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DEBRIS |
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MOLD SPORES |
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PET DANDER |
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CIGARETTE SMOKE |
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SMOG |
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WILDFIRE SMOKE |
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ALLERGENS |
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BACTERIA |
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VIRUSES |
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Can MERV 13 Filter Covid?
One benefit of MERV 13 filters is that they can filter microscopic particles like viruses. The particle size of the COVID-19 virus is 0.1 micron, a measure that MERV 13 filters are incapable of trapping. However, the COVID virus does not spread through the air on its own.
According to ASHRAE, the COVID virus spreads through respiratory droplets, which are much larger, approximately 1.0 microns or more. MERV 13 filters are 85% efficient at capturing particles of this size. Therefore, a MERV 13 filter is technically capable of filtering COVID. Use the highest-rated compatible filter if your HVAC system is incompatible with MERV 13 filters.Please bear in mind, though, that upgrading your air filter alone will not protect you against COVID-19.
When to Change MERV 13 Filter
MERV 13 filters should be changed every 30 to 60 days and, in some cases, more frequently. Pet owners, parents of young children, and persons with allergies or asthma might benefit from changing filters more often.
The filter’s quality determines how often the air filter needs to be changed. High-efficiency filters must be changed more often than lower-rated filters because they trap more contaminants. Assessing the filter every few weeks is a good practice.
Can MERV 13 Filter Covid?
MERV 13 filters will undoubtedly provide the best filtration for your home, but there are other factors to consider before using these highly-rated filters:
- Do circumstances (pollution, immune system, respiratory issues) warrant using a highly-efficient filter?
- Would a lower-rated filter provide adequate filtration for your needs?
- Is your HVAC system compatible with highly-efficient filters?
- Are you amenable to the higher cost and frequent changes of highly-efficient filters?
