man putting new ac filter into a system

Air Filters: Does a Higher MERV Rating Restrict Airflow?


Air Filters: Does a Higher MERV Rating Restrict Airflow?

air conditioner filter close upAir filters are one of the parts of HVAC systems that most homeowners are aware of – after all, we have to change our AC or furnace air filters every month to maintain air quality and efficiency.

But did you know that every air filter has a rating? And did you know that the rating actually matters? Just like a water filter in your fridge, your HVAC system and duct system are impacted by what kind of filter you choose for your home. And today, we’re going to be breaking down the air filter ratings so you know how they work and what to look at when you go to the store.

Understanding Air Filter Ratings

Air conditioner and furnace filters are an essential part of any home’s entire HVAC system and your indoor air quality. Your air handler has a filter to clean the air in your home, removing particles like pet dander, dust mites, tobacco smoke, mold spores, carpet fibers, and more – depending on the rating. High-efficiency filters pull more from the air with superior filtration and thicker filter material.

Every filter has a rating, but different systems mean different things. Common types of air filter ratings include MERV, MPR, and FPR. The higher the MERV rating (or other systems’ rating), the better the filtration.

MPR Ratings

MPR stands for “Microparticle Performance Rating” and was developed by 3M for their company’s air filters. The scale ranges from MPR 100 to MPR 2800, and it measures how well the air filter can capture microparticles between 0.3 and 1.0 microns large. While the scale has a wide range, AC systems use MPR 300 to 1900.

FPR Ratings

The Home Depot created the FPR scale for their branded filters, which stands for “Filter Performance Rating”. With this scale, which ranges from 1 to 12, you can filter out anything from big fibers to lead dust depending on how high the FPR rating is. Most people will use 4 through 10 in their homes.

clean and dirty air filters for homesMERV Ratings

MERV stands for Minimum Efficiency Reporting Value, and the MERV rating system ranges from 1 to 20. It was created by the American Society of Heating, Refrigerating, and Air Conditioning Engineers. High MERV filters can meet the standards for HEPA filters, bringing hospital-level air quality to spaces. However, for homes, the recommended MERV scale for homes is up to MERV 13.

Does Your Filter Affect Your HVAC System?

MERV 13 is the high MERV rating for your residential HVAC system – but why? What about the right MERV rating for commercial HVAC systems? Will a higher MERV filter affect how your air conditioning system runs – and what about a lower MERV rating?

Different MERV ratings DO impact your system! A high MERV filter affects airflow by reducing the total external static pressure of your system (causing a higher pressure drop). Higher MERV filters can even damage your system. A too-efficient air filter can cause air conditioner coil damage from freezing, your blower fan could work too hard and wear down the blower motor, reduced air velocity and less airflow through the ventilation system could create cold spots, your heat exchanger can crack, and your system will use more energy.

Why? The filter slows down the air moving through the system and clogs faster, decreasing efficiency and making your system work harder and longer for worse results!

man putting new ac filter into a systemFinding the Right Filter with Right Time HVAC!

Higher MERV ratings are not always better. A higher MERV-rated filter is good for better IAQ, but high MERV air filters clog faster, are more expensive, decrease air flow, increase pressure drop, and more. Make sure that when you’re choosing a filter, you’re choosing a rating for homes to prevent damage to (and decreased efficiency with) your system.

If you’re struggling to figure out the best filter for your system, or if you think that you’ve gotten damage to your furnace or AC after using the wrong filter, then it’s the Right Time to call our team! Our techs can put you back on track for comfort in your commercial or residential space. As a full-service HVAC company, we’ve got the tools and experience to help you out. Call Right Time HVAC for professional heating and cooling help in middle Tennessee!



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