Buying the right air filter is critical to keep you HVAC system running properly, but deciphering industry acronyms and ratings can make it difficult to know which filter you need. MERV and HEPA are the two most common HVAC air filter terms you’ll hear, and here’s a brief guide on what they mean.
MERV — The Key to Decoding Filter Efficiency
MERV, or minimum efficiency reporting value, is a numerical rating given to air filters to describe their effectiveness at trapping particles within a certain size range. The MERV rating scale goes from 1 through 20, and the higher the rating, the better a filter is at capturing particles. Here’s how some common types of HVAC filters rate on the MERV scale:
- Flat-panel fiberglass filters — Inexpensive, flat fiberglass filters typically have MERV ratings ranging from 1–4. They’re effective at trapping about 80 percent of airborne particles larger than 10 microns in size. While they can capture larger damaging particles and protect your HVAC system, they don’t improve air quality.
- Pleated media filters — These medium-efficiency fiberglass filters have ratings from 5–13, and the higher-rated versions can capture 95 percent of particles 1.0–3.0 microns in size so they’re more effective at cleaning the air.
- Higher-efficiency filters — Thicker pleated filters with MERVs of 14–16 are considered “higher efficiency.” To use this type of filter, your HVAC system will need to be modified or a bypass installed to avoid damaging airflow restrictions.
A knowledgeable HVAC technician can advise you on the best MERV rating range for your system, or you can check the filter ratings recommended for your equipment by the manufacturer.
HEPA Filter Basics
High-efficiency particulate arrestance or HEPA filters have MERV ratings from 17–20, and they’re able to trap up to 99.97 percent of particles as small as 0.3 microns. True HEPA filters are so dense that they restrict airflow significantly, so they’re not usually used in residential HVAC systems.
For help deciding which HVAC air filter is best for the system in your Dayton home, contact us at Detmer and Sons today.
Our goal is to help educate our customers in Dayton, Ohio about energy and home comfort issues (specific to HVAC systems).
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