What’s the Difference Between HEPA & MERV Filters? | Teems Electric

With so much focus on airborne nasties and how we can reduce them, many of us have found ourselves trying to sort through the many options in the HVAC filter aisle at the local home improvement store.

We do well to remember what size the return vent is, but they also want us to sort through a dozen other options. Some filters have numbers, some don’t—and all of them have more initials than a doctor’s office sign.

Fortunately, the ratings are easier to decipher than it may seem and your friends at Teems Electric are here to help.

What Are MERV Ratings?

MERV stands for minimum efficiency reporting values, which is a long-winded way of saying it’s a measure of how effective the filter is at catching things in the air. The point of an HVAC air filter is to capture those particulates to keep them from clogging up the air handling unit. A clogged unit will run less efficiently, driving up your power bill, and will likely fail far earlier than it should.

As an added bonus, some of these filters can improve the indoor air quality by removing things people can breath in and that might cause health issues. Depending on the MERV rating, that may include mold, allergens and, yes, even viruses. For efficiency, most experts recommend using the lowest MERV rating that accomplishes what you need it to.

  • MERV 1–4: These are basically just for capturing dust and larger particles that can cause problems in your HVAC air handler, with effectiveness ratings of less than 20% of 3- to 10-micron particles. The blue, spun fiberglass filters you see at the home improvement store are likely in this range.

  • MERV 5–7: At this level the filters stop 20 to 69% of those 3- to 10-micron particles, which doesn’t include nasties such as allergens and viruses.

  • MERV 8: These are 70 to 85% effective at stopping those larger particles, and are the lowest rating that can be expected to capture mold spores.

  • MERV 9–12: These are 85% or more effective at catching larger particles, and range from less than 50 to 90% effective at snagging particles in the range of 1 to 3 microns. That means they’re good enough to pull cooking odors and fumes from combustion engines out of the air. The American College of Allergy, Asthma & Immunology says filters rated 11 to 13 are best for capturing allergens such as pollen and dander

  • MERV 13 & Higher: These provide superior air filtering, to the point the American Society for Health Care Engineering recommends them for healthcare facilities. They generally capture about 75 to 100% of particles in the 0.03- to 1.0-micron range, which means they can stop many airborne viruses. They can also remove smoke from the air.

What Are HEPA Filters?

HEPA stands for high-efficiency particulate air, which is a way of saying filters designated HEPA can seriously clean the air. This type of filter is said to remove at least 99.97% of dust, pollen, mold, bacteria and other particles with a size of 0.3 microns or greater.

HEPA filters are in the range of MERV 17 to 20, and they are typically the most expensive options.

The HVAC experts at Teems Electric can help you set up a climate control and air filtering system that meets your needs. Give us a call today and let us get started on your project!