Air Conditioner Filter: Is More Efficient Necessarily Better?

Minimum efficiency reporting value (MERV) ratings are useful qualifiers, providing a uniform standard of A/C filter efficiency consumers can use to comparison shop. However, this shouldn’t be the only factor you consider when choosing a better A/C filter for your cooling system. Learn where MERV shines and where it fails in order to choose the best filter to use in your air conditioner.

Taken alone, one would suspect that the highest-rated MERV is the best filter to use, but this isn’t necessarily true. Here’s how MERV works to your advantage.

• MERV ranges from 1 to 16, with only high-efficiency particulate air (HEPA) filters achieving MERV 17 to 20 ratings.

• Low-efficiency filters in the 1 to 4 MERV range only capture large particles, those 10 microns or more. These filters offer your air conditioner the most basic protection against dirt particles.

• Mid-efficiency filters, or those between MERV 5 and 13, offer good protection for the HVAC system, as they generally trap particles down to 1 micron in size, while high-efficiency filters rate MERV 14 to 16, capturing particles 0.3 microns in size. However, only hospitals and labs use these filters, as they are not designed for residential use.

But MERV doesn’t tell the whole story. If you take into consideration particle size only, MERV will fail you, and here’s why:

• MERV only reveals the size of particles a filter can trap; it doesn’t take into account the other vital factor: airflow. Nor does it assess a filter’s efficiency over its lifetime. Instead, it measures only initial efficiency.

Taking airflow and lifetime efficiency into consideration, the best A/C filter is generally one in the mid-MERV range. These filters provide sufficient airflow for the A/C while improving in performance over time. How’s that possible? As the filter’s surface fills with particles, it becomes denser and therefore more efficient.

Sobieski Services is happy to help you select the best A/C filter to use with your system. Our goal is to help educate our customers in Delaware, Pennsylvania, Maryland and New Jersey about energy and home comfort issues (specific to HVAC & plumbing systems).

Image Credit: Destinys Agent