A Crash Course in HVAC Air Filter Ratings

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A Crash Course in HVAC Air Filter RatingsWhen shopping for HVAC air filters, you have probably noticed there are different styles and that many have a MERV number and that some are designated as HEPA filters. Here is what those ratings and acronyms actually mean and why they matter.

What is MERV?

The American Society of Heating, Refrigerating and Air Conditioning Engineers, known by the ASHRAE acronym, developed a helpful rating system for air filter efficiency. It is called the Minimum Efficiency Reporting Value, and you have likely seen this rating on air filters as MERV.

The numbered rating indicates three important factors about an HVAC air filter. These factors are the filter’s airflow resistance, its ability to trap particles and its general expected lifespan. Low numbers indicate less efficiency at trapping particles.

For example, some residential filters are rated only MERV 4. These will keep some dust out of the machinery but they will do little regarding small particles. For better indoor air quality, choose filters that are MERV 7 or higher.

What is HEPA?

HEPA stands for High-Efficiency Particulate Air. Ranking at MERV 17 and above, HEPA filters are touted for their superior air-cleaning benefits, but their use in residential HVAC systems is sometimes problematic. The dense design that makes these filters excel at trapping microscopic particles also makes them resistant to airflow.

The right volume of airflow is necessary for your heating and cooling system to operate normally, safely and efficiently. Hospitals and some other industries get away with using specialty HEPA filtration systems because their ventilation system is built differently. Some residential systems can develop problems due to the increased strain a HEPA filter will create.

Discuss with your HVAC technician whether or not HEPA filters are right for you. An alternative could be to choose an HVAC air filter with a MERV rating on the upper end of the residential-safe spectrum between MERV 7 and 12, and install extra air purifying measures, like a standalone HEPA air cleaner.

To learn more about choosing an HVAC air filter, please contact us at Hartman Brothers Heating & Air Conditioning.

Our goal is to help educate our customers in New Haven, Indiana and surrounding Fort Wayne area about energy and home comfort issues (specific to HVAC systems). For more information about HVAC filter ratings and other HVAC topics, download our free Home Comfort Guide or call us at 260-376-2961.

Credit/Copyright Attribution: “Palto/Shutterstock”

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