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Heating & Air Conditioning

Furnace filters: What does MERV mean?

At Whyte Ridge, we talk a lot about filters. That’s because the right filter can offer you a ton of benefits. 

Filters work to prevent dust, debris and allergens from being recirculated in your home through your heating, ventilation, and air conditioning (HVAC) system. This helps to keep your system running efficiently and ensures that air flow isn’t restricted. 

By removing contaminants, filters also help to keep the people in your home healthy. They can be an effective way to reduce irritants in your air and improve overall air quality, alleviating allergic and asthmatic symptoms and reducing the incidence of chronic illnesses.

So what does MERV mean?

MERV, or Minimum Efficiency Reporting Value, is a numerical indicator of a filter’s efficiency. It specifically measures the lowest performing level, or performance under worst case scenarios. This number is an excellent tool to help you compare filters and identify the right one for your particular needs. 

Ultimately, you’ll want to balance a filter’s efficiency with how much you can afford to spend. Make sure that you’re buying one that will adequately filter your air, which is important both for the long term maintenance of your HVAC system as well as for your own health. Higher quality filters are more effective at removing airborne contaminants and irritants.

How does the MERV rating system work?

MERV indicates how much a filter can trap at its minimum performance. The higher the value, the better it will work, in terms of the size of particles it will catch. Higher values are better at trapping smaller particles, making it especially important to choose a higher value if you have pets, allergies, or chronic illnesses.

The rating system starts at 1, but you should consider 6-8 a minimum value to adequately protect your HVAC system, although this range won’t provide particularly good filtration for smaller airborne particles.

Which MERV should I buy?

1-4: A filter with a MERV of this value will catch large fibers like carpet fibers as well as pollen and dust mites. It’s not generally considered sufficient for most homes or HVAC systems.

5-8: This is a minimum range for residences, with the ability to catch contaminants 3-10 micrometres in size. These filters will adequately capture mold spores, hair spray, and cement dust, but they won’t be as effective for smaller contaminants that trigger allergies. Homes with pets should also invest in better filters.

9-13: These filters cost more but provide excellent filtration and trap nearly all large particles. They’re effective for contaminants 1-3 micrometres in size. Filters with a MERV value in this range will provide you with better air quality in your home and are appropriate for pet owners and those with allergies.

14-16: Although we cautioned you against a filter with a lower MERV value, it can also be problematic to choose one with a value that’s too high. Filters in this range are more suited to medical facilities or sanitation applications with very high filtration requirements. Capturing contaminants as small as 0.3 micrometres, these filters are effective against airborne bacteria and tobacco smoke. However, they are very thick and can restrict air flow, causing a residential HVAC system to malfunction. Avoid anything above a MERV of 13 for your home purposes.

The bottom line

Being a homeowner comes with lots of responsibilities, and maintaining your HVAC system is one of the things we rarely think about until there’s a problem. Selecting the right filter can help keep your system functioning well, reduce your energy costs, and improve your indoor air quality. Using MERV as a guide, you’ll be more likely to choose the right filter for your needs. Just make sure you change it every 1-3 months (or more often if you notice it looks dirty). This will ensure optimal filtering and avoid restricted air flow from a clogged filter. 

Generally, a MERV of 8-10 offers a good balance between affordability and performance, and is appropriate for most residences. If you can afford it or if you’re concerned about pet dander, allergies, asthma, or chronic illnesses, consider investing in a slightly more expensive filter with a MERV of 11-13.

Want expert advice? Ask your Whyte Ridge technician to help you choose the right filter to keep your home comfortable and healthy, and your HVAC system working well.