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MERV Air Filter Ratings

Having a furnace filter, especially a clean, effective one, is very important for many reasons.  First, it cleans your air which reduces sickness and allergies.  Secondly, it allows your furnace to operate at its optimum efficiency.  A dirty or clogged filter makes your furnace work harder to put the same amount of warm air into your home.  We know that there are different types of furnace filters: disposable, HEPA, electronic, etc… but did you know that they could be classified even further?

Disposable filters are rated by energy efficiency on a scale of 1-20 with MERV (minimum efficiency reporting value) ratings.  20 is the best rating.


1-4: Filters with these ratings are typically used in residential window AC units and can stop pollen, cockroach debris, dust mites, sanding and spray paint dust, and textile and carpet fibers.

5-8:  These filters offer an improved filtration system for residential homes, and they are also used in industrial and commercial workplaces.  They will stop mold, spores, dust mite debris, cat and dog dander, hair spray, fabric protector, dusting aids, and pudding mix.

9-12:  These filters are used for superior filtration in residential homes as well as in hospital laboratories and for better filtration in commercial places. They block legionella, Humidifier dust, Lead dust, Milled flour, Auto emission particulates, and Nebulizer droplets.

13-16: Filters with this rating are used in hospitals and general surgery and can block bacteria, droplet nuclei (sneeze), cooking oil, most smoke, and insecticide dust, most face powder, most paint pigments.

17-20:  This high rating is for filters used in clean rooms, electronics, and pharmaceutical manufacturing.  They can block viruses, carbon dust, sea salt, and smoke.

Disposable filters can be purchased at a local hardware store or through your HVAC company. FLAME will install a disposable filter with a MERV rating of 8 during the annual maintenance exam (furnace inspection).  

For more information, please contact FLAME or check out Wikipedia’s article, minimum efficiency reporting value.

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