Who Is MERV And Why Is He Rating My HVAC Filter?

Posted On October 16th, 2019 by Lanz HVAC



Have you heard of MERV? If you haven’t, we at Lanz Inc. of Champaign-Urbana IL think it’s good to get acquainted with MERV - so you’re ready next time the topic of air filters comes up.

Meet MERV - the Minimum Efficiency Reporting Value which numerically measures the effectiveness of air filters for HVAC and furnace units. MERV uses a standardized scale from 1 to 16, with higher numbers indicating smaller apertures (or holes), that remove finer and finer foreign particles from the air you breathe - particles like pollen, dust mites and pet dander.

So MERV matters. Three things we want you to take away from this blogpost:

  • Not all air filters are MERV-rated.
  • The highest possible MERV rating may not be the best option for your home’s HVAC system.
  • Consult with the pros at Lanz Heating & Cooling to make sure you’re using the right filter - or just sign up for our exclusive Filter Fetch service and don’t worry about it.

We’ve introduced MERV to many customers over the years here at Lanz Inc. That’s because folks from all around Central Illinois, from Vermilion to Piatt and Ford to Douglas, have signed up for Lanz’s unique Filter Fetch service.

(Filter Fetch is offered to customers in the Lanz Comfort Family, and it delivers a new MERV-rated air filter - with the correct MERV rating for your heating and cooling system - right to your home. See more at LanzInc.com/comfort-club.)

But back to MERV. This precise measurement was created in 1987 by the American Society of Heating, Refrigeration & Air-conditioner Engineers (ASHRAE) to provide a standard, objective metric for determining the efficacy of an air filter.

What they came up with is a ranking system that assigns a number to a filter based upon its worst possible performance. Filters of MERV 4 and below can remove dust and pollen, but you need a filter of at least MERV 5 to reliably remove mold spores and pet dander.

Typically, modern residential HVAC systems support filters of MERV 8 through 12. These figures represent filtration devices that get rid of particles greater than one micron (1.0 μm) in diameter - such as lead dust, exhaust emissions and smog. MERV 13 filters are required to reliably remove particles of tobacco smoke.

(FYI, the MERV scale goes all the way up to 20, removing particulate matter as tiny as viruses. Filters that strong, however, are generally found in hospitals and cleanrooms.)


What MERV Rating Is Best For My Home’s HVAC System?

Well, the ASHRAE recommends homes use filters of MERV 6 or higher. The U.S. Green Building Council’s Leadership in Energy & Environmental Design (LEED) recommends MERV 8 or greater. The U.S. Department of Energy says to spring for MERV 13 or more.

Higher does not mean better. Not every HVAC unit can capitalize on the benefits of a high-MERV filter - in fact, sometimes a high-MERV filter can drag the airflow down.

A filter rating of MERV 13 will do more than remove 90% of particles larger than a micron - it will also create greater resistance to the air blowing through it. That hurts efficiency, and might even contribute to reduced motor life and worsened indoor air quality.

Plus, because high-MERV filters catch more debris, they need to be changed more often - and they might be more expensive, too. Talk with the professional HVAC consultants of Lanz Heating & Cooling Inc. to determine the right MERV level for your HVAC filters.

So, that’s MERV. Aren’t you glad you met?

To get to know MERV better, or learn anything else about your home’s HVAC or plumbing situation - just call Lanz Heating & Cooling Inc. at 217-355-5512, or visit LanzInc.com/contact.

Since 2002, Lanz Heating & Cooling Inc. of Champaign-Urbana, IL, has proudly served Central Illinois, including Champaign, Douglas, Piatt, McLean, Iroquois, Ford and Vermilion County, and Bondville, Pesotum, Savoy, Rantoul, Danville, Oakwood, Mahomet, Sidney, St. Joseph, Fisher and Gibson City.

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