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The MERV Rating of HVAC Filters for Better Air Quality in Your Home

Residential AC Repair & Replacement ServicesYour central AC system processes a lot of air. A typical HVAC system can blow approximately 400 cubic feet of air every minute per ton of cooling capacity, so a modest 3-ton unit will blow up to 1,200 CFM. That’s equivalent to an Olympic-size swimming pool of air every 73 minutes. To keep the air clean of contaminants and odors and prevent unnecessary Spring AC services, your system has at least one air filter. Air passes through the filter, which trap most air borne particulates. However, there are several different types of air filters. They offer varying levels of performance, which is measured by the MERV, or maximum efficiency reporting value, system.


These are the inexpensive filters you can buy for just a few dollars at your local big box store. You can identify them by how thin they are — typically just 1-inch thick. The fiberglass sheets do a decent job at filtering larger particles like dust and pet fur, but with a MERV of 1 to 4, fiberglass filters will not capture bacteria and other small particles. Fiberglass filters are better than nothing and will prevent dust from building up on your cooling coils, but most HVAC systems will benefit from higher MERV rated filters. On the plus side, they are dirt cheap, and you do not have to replace them often. Knowledgeable Spring AC repair professionals will tell you to check them every 2 to 3 months and replace when they become dirty.


Pleated filters have MERV ratings between 5 and 12. At these ratings, pleated filters can capture some smaller particles like dust mites and pollen without impeding airflow too much for aging systems. To help reduce the need for Spring AC services, check every 1 to 2 months, and replace if you can see any buildup of dust on the pleats.


High-efficiency filters are also pleated, but they use a more tightly woven fabric and can capture bacteria, tobacco smoke, and even toxic pesticide particles. The higher MERV rating of 14 to 16 carries a slight price premium, and you will need a newer, more efficient HVAC system to take advantage of these filters. Check every month, and replace when they become dirty or at least twice per year.


Many of our customers are interested in HEPA filters for their HVAC systems, but these filters are almost never installed in residential systems. Most residential systems lack the power to push air through HEPA filters, which have extremely tiny pores that capture nearly all particulates regardless of size. With MERV ratings ranging from 17 to 20, HEPA filters are most often installed in hospitals and other facilities that require extremely sterile air.

Want to learn more about how air filters help prevent the need for a Spring air conditioning repair? Check out our maintenance and Spring AC repair services, or speak with one of our heating and cooling pros at 281-477-3700 today!

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