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What is the Best MERV Rating for Furnace Filters?
When buying your furnace filters, you likely have to choose which MERV rating you want. If you don’t know what this means, or think it doesn’t matter, we’re here to help. First, let’s go over the importance of having furnace filters in the first place.
These important elements are designed to protect your HVAC system’s interior from dust and dirt, which can damage the unit and ducts. They are also designed to boost the quality of your indoor air, keeping allergens such as dust mites and mold spores at bay. Let your furnace filters clog up with dust, and you may as well not even use one at all!
Now, onto MERV. This stands for Minimum Efficiency Reporting Value – a benchmark of standards showing how effective a particular air filter removes large and small particles from the air. The numbers range from 1 (lowest quality) to 16 (highest quality), with some going up as high as 20. However, just because you buy a higher MERV like 16, doesn’t mean it’s necessarily right for your needs.
In fact, filters rated 7 to 12 are just fine for residential use. If you buy anything higher rated, it costs a lot more money and your system probably isn’t even designed to handle it. Those higher rated furnace filters are used by hospitals, labs, clean rooms and some manufacturing facilities. If you don’t own one of those things, you don’t need anything above a 12—which filters out most household irritants like dust, dander, spores, and bacteria. These can all cause allergies.
Here at Filtration Montreal, we recommend MERV 11-rated filters for the higher spectrum filters, which trap 65 to 79 percent of average particles of 1.0 to 3.0 microns in size, with an average particle size efficiency of 85 percent or better. We don’t carry MERV 12 filters, but they’re not that much better than 11s, as they trap 80 to 89 percent of average particles of 1.0 to 3.0 microns, with an average particle size efficiency of 90 percent or better.
That being said, the number on the side of the furnace filter box isn’t quite as important as where they were made. Even a MERV 8 that’s made in North America is better than a MERV 11 made in China or India, where the quality is so low, you’re paying for nothing. That’s because these countries are far less regulated in terms of air filter requirements. Always look for that “Made in North America” label, no matter which rating you settle on.
Just keep in mind that the EPA says medium efficiency filters with a MERV rating of between 8 and 11 are efficient at filtering small to large airborne particles.
Another consideration that's more important than the number is your changing schedule. You could buy the best MERV rated filter on the market but if you don’t change it as recommended, it’s not gong to work as directed. Most filters last a few months. Mark your calendar so you don’t forget to replace or clean it.
Filtration Montreal has some great deals on furnace filters right now, with a variety of MERV ratings. Come check us out and buy in bulk. Hey, you can even share with your friends for the holidays!