What Do MERV Ratings Mean?

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It’s easy to forget about your HVAC air filter, but this component can greatly improve your indoor air quality if you give it the attention it deserves. First, make a habit of checking your air filter once a month and changing it when it appears dirty. Then, consider upgrading to a filter with a higher MERV rating.

Are you unfamiliar with MERV ratings and what they mean? Here’s what you need to know.

What are MERV Ratings?

MERV, or Minimum Efficiency Reporting Value, is a standard rating system established by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). MERV ratings report how efficiently a filter captures particles between 0.3 and 10 microns in size. In other words, they indicate HVAC filter efficiency.

A Breakdown of MERV Filter Ratings

The MERV scale ranges from 1 to 20. The higher the number, the more particles the filter can catch. With this knowledge, you may be tempted to buy a MERV 20 filter without learning more, but that would be a mistake. Here’s a breakdown of MERV ratings and why choosing a mid-range filter is probably the best choice.

MERV 1-4: Disposable Fiberglass Filters

The products within this range are what many people think of when they picture HVAC filters. A one-inch thick spun fiberglass filter is designed to trap dust, lint, carpet fibers, and other relatively large airborne debris no smaller than 10 microns. This level of filtration does little more than prevent dust from settling on the HVAC equipment.

MERV 5-8: Disposable Pleated Filters

Made of cotton or polyester, this popular type of filter removes allergens down to 3 microns. This includes mold spores, dust mites, aerosol spray, and pet dander. This level of filtration is ideal for basic residential applications because it’s more efficient than MERV 1 to 4 filters but not so densely woven that it restricts airflow.

MERV 9-10: Electrostatic Filters

Self-charging cotton or paper fibers attract particles as small as 2 microns, including milled flour and auto emissions. Homes with children, pets, smokers, or people with sensitive respiratory systems may benefit from this level of filtration. Washable electrostatic filters are more expensive than their disposable counterparts, but the ability to clean and reuse the filter for several years makes it an economical, low-waste choice.

MERV 11-12: Rigid-Style Cartridge Filters

At 6 to 12 inches deep, this type of filter can trap large bacteria, lead dust, and other particles down to 1 micron. While a rigid-style cartridge filter can be used in residential applications, it requires special housing to be installed.

MERV 13-16 High-Efficiency Pleated Filters

This option is comprised of pleated synthetic cotton attached to a metal frame. Filters at these high MERV ratings can sift out tobacco smoke and tiny bacteria down to 0.3 microns. Such advanced filtering capability requires hefty airflow, so it’s rare to see these high-efficiency filters installed in residences. Instead, they’re usually found in hospitals, surgical centers, and smoking lounges.

MERV 17-20: HEPA Filters

HEPA stands for High-Efficiency Particulate Absorption. These filters are the best of the best, with tightly woven fibers that trap at least 99.97 percent of particles smaller than 0.3 microns, including carbon dust, combustion smoke, and viruses. HEPA filters are often used in vacuum cleaners.

Choosing the Right Air Filter

Based on the above breakdown, you could probably benefit from choosing a filter rated 5 to 8 on the MERV scale. If you have no pets or allergies, MERV 1 to 4 might be acceptable. Then again, if you have severe asthma or several furry pets, you may want to select a filter in the MERV 9 to 10 range.

If you’re interested in going higher than MERV 10, ask your HVAC contractor for tips. It may be necessary to boost the blower speed to maintain proper airflow if you choose such an efficient filter. Before you go this route, remember to consider the higher filter price and extra cost of operating your equipment. Once you select the ideal air filter for your home, remember to clean or replace it once a month or according to the manufacturer’s directions.

Schedule HVAC Services in Central Florida

For more help choosing an air filter based on its MERV rating, or to ask other heating and cooling questions, turn to Certified Climate Control. Our technicians have years of experience installing and servicing HVAC systems. We also operate as a preferred dealer for Daikin, Bryant, and other leading HVAC brands and retain an A+ rating with the BBB for your peace of mind. Contact us today to schedule HVAC services in Orange, Seminole, or Volusia County, FL.