A Guide To Furnace Filter MERV Ratings - [With MERV Comparison Chart]

Furnace air filters work the same way for our homes that face masks work for doctors. The air filter you use in your home's furnace collects particles that would otherwise travel through your vents into your living room or bedroom and cleans the air that you breathe, all the while preventing potentially harmful allergens such as dust, dander or other types of debris from entering your lungs.

Essentially, the air filter you use acts as a last line of defence for the invisible threats flowing through the air that can terrorize your sinuses or irritate your skin.

Many Canadians don't realize that there are some drastic difference between the types of furnace filters you can use in your home. You may have come across something called a "MERV rating" and different furnace filters have different MERV ratings displayed on them.

Turns out, depending on your unique environment, you may require a specific type of filter for your home. Well, in order to understand the difference, we must first get acquainted with how the MERV rating scale works.

What's is a "MERV" rating?

MERV stands for minimum efficiency reporting value and it was designed by the ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) in 1987. It measures how small of particles a filtration product, such as a furnace filter, is able to capture.

The MERV system was designed to help improve the quality in the air filter industry and to help with effectiveness in the production in air filters themselves. As well, it makes it a lot easier for consumers to easily compare the quality of furnace filters regardless of the brand or who is selling the product.

The MERV scale ranges from 1 to 20, and on the lower end of the scale MERV 1 filtration can capture particles as small as 10 microns with 65% efficiency, and on the higher end of the scale MERV 20 filtrations can capture particles as small as 0.3 microns with 95% efficiency.

(Don't worry, we will have a full comparison chart at the end of this articles where you can visually see the difference in what each MERV rating is capable of filtering.)

MERV is the most commonly used rating scale and is trusted by engineers, HVAC techs and indoor air quality professionals around the world. There are other rating systems, such as MPR, but are often used with only 1 specific brand or in limited products and therefore is less useful when you want to compare product to product, and also less trustworthy compared to the MERV rating system.

When browsing for furnace filters you typically see most filters are rated from MERV 8 to MERV 13, but sometimes can go as low as MERV 4 (like the low quality fiberglass filters) and as high as MERV 16. Chances are, you will probably find yourself comparing MERV 8 to MERV 13 filters.

So which MERV rating is appropriate for your home?

Well it really depends on your needs, where you live, who live's in your home and any health conditions you may have. We are going to go into details for 3 of the most common MERV ratings (8, 11 and 13) and also provide the full MERV comparison chart below.

How to choose the right MERV rating for your furnace filter

Before you start to get into specific MERV ratings, it's important to get an idea of your unique home environment and get a sense for all the important factors that may be affecting your air quality.

Here are some of the main indoor air quality factors to consider and reasons why you may want to upgrade to a higher MERV:

Location - Where your home is located is very important. Living in a city, near construction, near wildfires or near a major highway are all factors that can potentially worsen your indoor air quality.

Residents - Who lives in your home plays a big role. Small children and elderly residents have developing or weakened immune systems, so indoor air quality can have a larger impact on their health. Also, generally speaking, the more people living inside a home, the worse the air quality tends to be. 

PetsPets can have a severely adverse affect on your air quality. Dogs and cats shed and leave dander floating around in your air.

Allergies/Asthma - Anyone suffering from asthma or allergies is important to consider. These respiratory illnesses can be extremely sensitivity to particulates and contaminants in the air.

Smokers - Tobacco smoke can linger in a home for long periods of time. Smokers living in the home, even if they do not smoke inside, can have a harmful effect on your indoor air quality.

Cooking/Cleaning - Frequency of cooking and cleaning can have a negative impact. Each time you cook the vapours emit from the kitchen into your air. Every time you clean, harmful odours and volatile organic compounds (VOCs) are released into the air. 

Make sure to get a good idea of your home environment before familiarizing yourself with the MERV ratings discussed below.

MERV 8 - The Filter For Average Homes

MERV 8 filtration is capable of capturing particles between 3.0 micros and 10.0 with 90% efficiency. A MERV 8 furnace filter is perfect for the average household, it is far superior than fibreglass or synthetic panel filters. 

A MERV 8 furnace filter is able to trap:

  • Common dust

  • Debris

  • Pollen

  • Mold spores

  • Hair spray

  • Fabric protector

  • Cement dust

It's important to note that a MERV 8 filter CANNOT capture auto emissions or pet dander.

PureFilters offers a wide variety of MERV 8 furnace filters in just about any size.

 

 

MERV 11 - Homes That Need Superior Filtration

MERV 11 filtration is capable of capturing particles between 1.0 micros and 3.0 with 95% efficiency. A MERV 11 furnace filter is perfect for anyone with small children and or pets in their home.

A MERV 11 furnace filter is able to trap:

  • Common dust

  • Debris

  • Pollen

  • Mold spores

  • Hair spray

  • Fabric protector

  • Cement dust

  • Pet dander

  • Car fumes

It's important to note that a MERV 11 filter CANNOT capture smoke or bacteria. 

PureFilters offers a wide variety of MERV 11 furnace filters in just about any size.

 

MERV 13 - Homes That Need An Advanced-Level of Filtration

MERV 13 filtration is capable of capturing particles between 0.3 micros and 1.0 with 98% efficiency. A MERV 13 furnace filter is perfect for anyone suffering from allergies, asthmas or have elderly residents and anyone with compromised immune systems.

A MERV 13 furnace filter is able to trap:

  • Common dust

  • Debris

  • Pollen

  • Mold spores

  • Hair spray

  • Fabric protector

  • Cement dust

  • Pet dander

  • Car fumes

  • Smoke

  • Bacteria/virus carriers

  • Microallergens

Anything above a MERV 13 rating is typically meant for clean rooms, surgical rooms or radioactive filtering.

PureFilters offers a wide variety of MERV 13 furnace filters in just about any size.

  


MERV Rating Comparison Chart

merv rating chart 

Should you upgrade MERV ratings?

Although MERV 8 should be perfectly fine for most households, the cost of an upgrade isn't all that substantial. We did a detailed comparison between a MERV 8 and a MERV 13 filter, and the differences are quite drastic. Customers that have upgraded from MERV 8 to MERV 11 or MERV 13 have told us they've noticed a drastic difference in their homes, citing:
  • Improvements in sleep
  • Less headaches
  • Increased energy
  • Overall higher quality of living

We spend a large portion of our day, why not maximize the quality of air that we breathe in?

Get started today and select a furnace filter with a MERV rating that's appropriate for your home! PureFilters is Canada's largest furnace filter and air filter supplier, we carry all sizes and brands and provide outstanding customer support.

If you have any questions about MERV ratings, feel free to email us at support@purefilters.ca or call us at 1-888-979-4284.