MERV Filters and Ratings – What Are They?

Upon searching for air filters in Phoenix, you have to sift through a few details to find the right fit. Size, brand, and material are all essential variables, of course, but one factor is often overlooked: the MERV rating of an air filter. MERV ratings offer a better insight into just how efficient you can expect any filter on your list to be and how effective it really is at filtering various types of particles out of the air within your home. Taking the time to learn a bit about these ratings and how they impact your air conditioner’s performance can help save you time, money, energy, and effort in the coming years.

What Are MERV Ratings?

MERV stands for “Minimum Efficiency Reporting Value” and is a system used to determine how efficiently an air filter can clean the air in your home with each use. Each filter is assigned a rating based on how much debris a filter manages to block when circulating air. These ratings lie on a scale of 1 to 20. The higher the MERV rating, the better the filter is at keeping the air free and clear of pesky particles. The score reflected by the rating is the bare minimum at which a particular filter is expected to perform based on a series of thorough tests.

How Are MERV Ratings Determined?

To receive a MERV rating, a filter must be tested to determine how well it can block particles of various sizes. Twelve differently sized particles are tested throughout the process, ranging from 0.3 to 10 micrometers in diameter. The particles being tested are grouped into three distinct categories:

• E1 – particles measuring 0.3 to 1.0 micrometers
• E2 – particles measuring 1.0 to 3.0 micrometers
• E3 – particles measuring 3.0 to 10.0 micrometers

During the test, particles are thoroughly counted and then sprayed through the filter in question. Any particles that make it through to the other side of the filter are then counted again. A filter is put through 6 tests of particles from each category, meaning that a filter goes through a whopping 72 tests before the final MERV rating is decided. At the end of the test, the worst score from each category is used to determine the rating, thus giving the minimum efficiency that the particular filter can be expected to work at. Filters may work more effectively than their score suggests at times, but the MERV rating is meant, after all, to reflect the minimum filtering capacity of a particular product.

What MERV Rating Is Right for a Home?

As mentioned, the higher the MERV filtration test score, the more particles a filter can pull out of the air in your home. However, that doesn’t mean that you should immediately invest in a filter with a MERV rating of 20 and call it a day. That’s the last thing you would want to do for an average home. Hospitals, nuclear power plants, and other buildings that require a particular emphasis on a completely sterile environment generally use filters rated 16 through 20. These filters are thicker, which, while helping them block more debris from the air. While this is beneficial in specific industrial and medical environments, the thickness of filters with these ratings contribute heavily to pressure drop when used in conjunction with the air conditioning systems typically installed in residences.

Pressure drop refers to how much a particular filter restricts airflow. Pressure drop most often occurs when a filter goes too long without being changed, but can also happen if you have a filter that’s too thick and powerful for the system you pair it with. Pressure drop can contribute to your air conditioning unit’s many issues, including short cycling, undue wear and tear on parts, and even complete failure if the problem goes unchecked for too long. To avoid the unfortunate effects of pressure drop, it’s usually recommended that the average home use filters with a MERV rating between 5 and 13. Of course, even when using a filter that falls between these ranges, it’s always a good idea to invest in regular inspections from a team of Phoenix air conditioner professionals to ensure everything is working smoothly.

Which Filter Should You Choose?

Though it’s viable to use an air filter with a rating of 5 in your home and still reap some benefits, most homes’ ideal range lies between 8 and 13. This range gives you nearly as much particle blockage as MERV filters with higher ratings while maintaining appropriate pressure levels to keep your energy bills low and your air conditioning unit working smoothly. Finding the balance between particle filtration and air resistance is the key to choosing the right filter for any space.

Each rating has its limits to consider and blocks different amounts of household debris from each category.

• MERV 8 filters block basic dust, pollen, mold, bacteria, and dust mites
• MERV 11 filters block dust, pollen, mold, bacteria, dust mites, and pet dander
• MERV 13 filters block all the particles that the previous rating blocks, plus cooking oil smoke, virus carriers, smoke, and smog.

The higher the rating, the more unwanted pollution the filter will keep out of your home’s air. However, the higher your rating, the higher your monthly energy bill might be because your AC unit is working harder to push air through a thicker filter. This is something to consider when making your choice. Consulting a trained AC repair and maintenance professional in Phoenix can give you a good idea of which particular air filter might be the best fit for your home and your needs as a homeowner.

Do MERV Filters Require Maintenance?

Filters with a high MERV rating need to be replaced regularly, just like any other filter. Over time, particles build up on the filter and make it harder for air to pass through, contributing to more strain on your system. This is especially true for filters with higher MERV ratings, which already place a bit of pressure on a system simply due to their thickness. Generally, it’s recommended that filters are replaced monthly or otherwise according to the recommendations on a filter’s packaging. Fortunately, the process is usually an easy, straightforward one and can be done without calling in a professional.

Learn More About Keeping Your Air Clean

Contact Howard Air to learn more about keeping the air in your home as clean as possible while maintaining your air conditioning system and keeping your monthly energy budget under control. If you’re unsure of which filter to use in your home, schedule an air conditioning inspection in Phoenix, AZ. One of our highly knowledgeable technicians can get you pointed in the right direction in no time and ensure the rest of your air conditioning system is running smoothly and safely to bring you the results you need for year-round comfort in the southwest.

Featured Image: Shutterstock / Sucharas Wongpeth