MERV vs. HEPA vs. Activated Carbon: Choosing the Right Air Filtration for Your Home
Indoor air pollution is a top environmental health concern for homeowners in Urbana, IL. Whole-house air filtration is often the most effective way to eliminate pollution in the home. Let’s explore three main types of filtrations that you’ll encounter.
Air Filtration
There are many different approaches to air filtration. The two we’ll focus on here are mechanical filtration, such as MERV and HEPA filters. We’ll also consider absorbent filtration, such as activated carbon. Many conventional air purifiers combine mechanical and absorbent filtration.
Mechanical Air Filtration
Pleated filters made with paper or synthetic fibers are examples of mechanical filtration. This approach is most effective at trapping particulate matter, such as dust, pollen, and pet dander. There are four core mechanisms through which mechanical filtration works:
- Straining
- Inertial impaction
- Interception
- Diffusion
Straining is what occurs when the openings in the filter are smaller than the diameter of the particles. Inertial impaction occurs when a sharp change in airflow causes many particles to collide with the interior fibers. Interception is the process through which smaller particles bounce around until impacting with the filter. Diffusion is the random capture of smaller particles due to the time spent in the filter.
Absorbent Air Filtration
Absorbent filtration involves taking on particles and then causing them to bond and become trapped. This form of filtration is often most effective with odors, gases, and airborne chemicals. While these are all particles, they are not as easily trapped through mechanical filtration.
Minimum Efficiency Reporting Value
The HVAC industry developed the minimum efficiency reporting value scale, or MERV for short, as a standard way to measure the effectiveness of mechanical air filters. MERV is a scale that ranges from one to 20. MERV filters that have a rating of one to four are the least effective. They trap less than 20% of particles that are 3.0 microns and larger. At a level of MERV 7, there’s tangible filtration of particles between 1.0 and 3.0 microns in size. At MERV 11 and above, filtration of particles can be achieved between 0.3 and 1.0 microns in size.
Dust and pollen are typically 10 microns in size or larger. Pet dander can be as small as 0.1 microns, and mold spores as small as three. You may see references to particulate matter 10 (PM10) and 2.5 (PM2.5). PM10 can have short- and long-term adverse health effects. That said, PM2.5 is even more dangerous since you can inhale it deeply into your respiratory tract. Modern medicine links long-term exposure to poor indoor air quality to many respiratory and cardiovascular diseases.
HVAC Filters
The more effective an air filter is, the less air that moves through it. This is an important consideration for central cooling and heating systems. Most modern HVAC systems support MERV filters that are between eight and 12. It’s a good idea to use the highest rating your system allows. You’ll trap more particles that way. You never want to exceed what your system supports. Doing so can add strain on your HVAC system, increasing operating costs and wear and tear.
Air Purifier Filters
Manufacturers design air purifiers to operate at higher air pressure. That’s why many air purifiers that use a MERV filter have a MERV rating of 14 and above.
High-Efficiency Particulate Air
Hospitals and medical offices typically use HEPA filters for optimal indoor air quality. Over the years, innovation has reduced the prices of this equipment, which has made them more viable for home use. HEPA filters are not common for HVAC. They are quite common in whole-house air purifiers. HEPA filters are superior to even MERV 16 filters and above because they trap at least 99.97% of all particles of all sizes.
Activated Carbon
Even HEPA filters aren’t effective at trapping volatile organic compounds, gases, and chemicals. That’s where activated carbon is beneficial. It’s a form of carbon that is very porous. It boasts substantial surface area that can absorb and trap odors, VOCs, ammonia, and other contaminants.
Cleaner and Healthier Home Air
Dogtown Heating, Air & Plumbing has locations in Urbana and the surrounding areas. We help our clients support healthy indoor air quality through testing, high-quality HVAC filters, whole-home air purifiers, UV lamps, humidity control equipment, and more. Our team performs seasonal tune-ups and is available around the clock for emergency repairs. We install and service boilers, furnaces, heat pumps, air conditioners, and ductless mini-splits. We also have plumbers on staff for installations and repairs, including drains, piping, water heaters, and garbage disposals.
To schedule an on-site consultation or service appointment or to learn more about our maintenance agreement, call Dogtown Heating, Air & Plumbing today, or contact us online.
