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Choosing the Right MERV Rating for your Furnace

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Whether you have just had a new furnace installed or you need a tune-up, your furnace filter is something you need to be aware of when caring for your furnace. This is especially important here in Alberta, as your furnace is an essential part of your home. 

Taking proper care of your furnace can help improve its life and efficiency. Selecting the right filter for your furnace may be more important than you thought. But how do you know which one is right for you? This is where the MERV rating is useful. 

What is a MERV Rating 

To help residential and commercial owners understand what furnace filter is right for them, the American Society of Heating, Refrigerating and Air Condition Engineers designed the Minimum Efficiency Reporting Value (MERV) rating system. For residential purposes, this system goes from 1-16, with 17-20 being for high-end commercial use. 

The scale works by determining the size of particles the filter can catch. The higher the MERV rating, the smaller the particle size it’s able to catch. This rating system is essential when selecting the right furnace filter for your home or building’s furnace. 

Why Do MERV Ratings Matter? 

Everyone’s home is different, and so are their furnace needs. Depending on the home or building, a higher rating might be needed. If people in your building deal with certain health conditions or have air quality requirements, you may need a higher MERV rating.

Having a higher rating can help your furnace: 

  • Reduce allergy symptoms for people in the building 
  • Limit bacteria and viruses, protecting people in the building 
  • Improve the building’s air quality

Selecting the Right MERV Rating 

Selecting a furnace filter with the right MERV rating may seem confusing, but there are a couple of things you need to know before you start your search. 

Health Conditions 

One of the major considerations to make are the health conditions of those within your home or building. While having a high air quality is important for everyone, those with certain health conditions can have an especially hard time living in areas with poor air quality. 

Having a higher MERV rating (one as close to 10 as possible) can help limit the bacteria and other particles that can make these conditions worse. This higher MERV rating can also help people with allergies. 

Maximum MERV Rating 

Before you purchase any furnace filters, it’s important to check your furnace’s maximum MERV rating. For homes without health conditions, a MERV rating around 7 or 8 would be best. This rating provides good air quality while still being cost-effective. 

A man replacing a furnace filter with a brand new, clean one

Different Types of Furnace Filters 

Your furnace filter is a crucial component of your furnace. Every time your furnace runs, some substances could enter back into your home from your ducts. Your furnace filter stops these from entering your home and also protects your furnace. These substances include: 

  • Dust 
  • Pollen 
  • Pet hair or dander
  • Smoke and fumes 
  • Mould spores and mildew 
  • Bacteria 
  • Viruses 

Disposable Filters 

Disposable filters have the lowest MERV rating, typically between 2-3. These filters are often made of fibreglass or other synthetic fibres. While they’re cheap, they only catch about 20% of particles between 3-10 microns in size. 

Disposable Pleated Filters

Disposable pleated filters differ in design from regular disposable filters. With a cardboard frame and wavy design, they can collect more particles. Typically, disposable pleated filters will have a MERV rating of around 8. This rating allows them to catch 84.9% of particles between 3-10 microns in size. 

Disposable Pleated High-MERV Filters

Selecting a high-MERV disposable filter could mean MERV ratings as high as 13. With particles between 3-10 microns in size, these filters are catching up to 90% of particles. This high-MERV rating is making the air in your home or building significantly cleaner. 

Electrostatic Filters 

Electrostatic filters can be both disposable and reusable. These filters can vary in MERV ratings depending on their quality. In some cases, a disposable version can be rated as low as 2. Meanwhile, some reusable filters can be as high as 10. For the reusable filters, this could mean catching 85% of particles between 3-10 microns. 

Finding Your Sweet Spot 

When it comes down to it, everyone’s homes have different needs, and so do your furnaces. The MERV rating system is an excellent way to measure the effectiveness of your furnace’s filter and in determining what filter to purchase. 

If your home or building doesn’t have anyone with severe health conditions, consider finding a filter that has a MERV rating between 7-8. If you have health conditions, search for a filter with a rating as close to 10 (if not higher). 

If you have any questions about your furnace filter or are interested in learning what filter is best for you, give us a call! Our team is here to take care of all your furnace needs. 

Written by Ryan Tutak

Ryan is considered one of Calgary's most knowledgeable residential HVAC specialists. Working in the industry for over 12 years, he's helped thousands of homeowners with their heating and cooling systems. Outside of running Calgary's most reputable HVAC business, you can find him on the Golf course practicing his short game or traveling with his family. His main goal is to create a positive collaborative culture, one in which his employees are excited to come in and are motivated to work hard. He spends the majority of his day working directly with Home Comfort Advisors, Service and Maintenance Technicians, and Customer Service Representatives ensuring they are fully prepared to lead the Home Service Industry in Customer Service.
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