What are MERV Ratings and Do They Matter?

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As HVAC cleaning specialists in Arvada, CO, we understand the importance of air filters in domestic air conditioning systems. And as part of our series on air conditioning cleaning and maintenance, we wanted to put together a guide to the different types of filter commonly available today, in the hope that it would help people to choose the right types for their specific needs.

If you happen to live close to us, you are more than welcome to call and request more information at any time, either about filters or our air vent cleaning and duct cleaning services. In the meantime, let’s get started with a brief explanation of why air filters are so important.

Why Are Air Filters Important?

Air filters play a crucial role in maintaining indoor air quality by removing pollutants, allergens, and other contaminants from the air. Whether you hire a professional vent cleaner on a regular basis or not (and you absolutely should!), you will still need to pay careful attention to the type of filters you install in order to maximize the performance of your domestic HVAC system. However, with so many different makes and types of air filters available, it can be difficult to know which ones are the best choice for your system. This is where Minimum Efficiency Reporting Value (MERV) ratings could come in handy. But how useful are they in reality? In this blog post, we will explain what MERV ratings are and whether they really matter.

What Are MERV Ratings?

MERV ratings are a system used to measure the efficiency of air filters. The rating consists of a numerical value between 1 and 20 that indicates how well the filter in question captures particles of different sizes. The higher the MERV rating, the better the filter's ability to capture smaller particles, such as pollen, pet dander, and dust.

Individual MERV ratings are determined by testing a filter's performance: how well it captures particles of different sizes. The filters are then assigned a MERV rating based on how well they do during the tests, i.e. how efficient they were at capturing different-sized particles.

MERV Rating Scale

The official MERV rating scale ranges from 1 to 20, and is often broken down into the following categories:

  • MERV 1-4 - These filters capture larger particles (3-10 microns) at 20% efficiency. Particles of this size may include dust mites, pollen, and textile fibers. This type of filter is typically made of disposable fiberglass.
  • MERV 5-8 - These filters capture particles of 3-10 microns in size at greater efficiency. They are usually made of pleated filter paper or cotton. A MERV 6 rated filter will capture such particles at 50% efficiency while a MERV 8 rated filter should do so at 85% efficiency.
  • MERV 9-12 - These filters capture particles from 1-10 microns in size, which may include lead dust and humidifier dust. They are typically made of deep pleated filter paper. A MERV 10 rated filter will capture 3-10 micron particles at 85% efficiency and 1-3 micron particles at 50-65% efficiency. A MERV 12 rated filter will capture 3-10 micron particles at 90% efficiency or greater and 1-3 micron particles at 80-90% efficiency.
  • MERV 13-16 - These filters capture particles from 0.3 microns in size, such as bacteria and tobacco smoke. They are usually made of pleated filter paper. Within this group, a MERV 14 filter will operate at 90% efficiency for 1-3 micron particles and 75-85% efficiency for 0.3-1 micron particles.
  • MERV 17-20 - These filters capture particles larger than 0.1 microns, such as viruses and carbon dust. They are typically made of high-efficiency particulate air (HEPA) filters. Most manufacturers do not recommend air filters with such a high MERV rating for domestic applications as they could slow the airflow considerably.

Do MERV Ratings Matter?

In our opinion, as HVAC cleaning specialists, the short answer to this question is yes, MERV ratings do matter. A higher MERV rating indicates that the filter in question is more efficient at capturing smaller particles, which can improve indoor air quality and reduce allergy and asthma symptoms. This can only be a good thing for everybody in your home.

However, it's important to bear in mind that not all HVAC systems can accommodate filters with very high MERV ratings. Using a filter with a higher MERV rating than your system can handle could restrict the airflow and decrease the system’s efficiency to a point where it becomes a real problem. For this reason, we recommend that you consult an HVAC professional to determine which MERV rating is appropriate for your system before you rush out and buy any new filters.

Additionally, it’s worth remembering that higher MERV-rated filters typically need to be replaced more frequently than lower-rated filters, as they capture more particles and become clogged more quickly. Whatever MERV rating you choose, we urge you to follow the manufacturer's recommendations for replacing your air filter, to ensure optimal system performance and indoor air quality at all times.

Final Thoughts From Our Arvada Duct Cleaning Team

As HVAC maintenance professionals, we see the results of people’s filter choice firsthand on a regular basis. We also see the effect of changing air filters on a regular basis but never cleaning the vents or ducting, which is a mistake in our professional opinion. For this reason, we urge you to search for ‘duct cleaning near me’ and find a local pro to clean your system soon, or to call us if you live nearby.

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