HEPA and MERV Air Filters

No doubt you’ve heard about HEPA (High Efficiency Particulate Air) filters, rightfully touted as highly efficient air filters that trap the tiniest of particles, keeping them out of the circulating air in a building. But do you know about MERV, which stands for Minimum Efficiency Reporting Value? MERV is the industry rating system for how efficient air filters are. And though 3M and Home Depot have their own rating systems—Microparticle Performance Rating (MPR) for 3M and Filter Performance Rating System (FPR) for Home Depot—MERV is the industry standard.

So what else should you know about HEPA and MERV filters, and how do you choose between HEPA and MERV filters for your home?

HEPA Filters

HEPA filters are seldom found in a residential HVAC system. In fact, a typical HVAC system cannot accommodate HEPA filters. They are too large, and the filtration is so dense they would bog the system down, slowing airflow so that the system couldn’t cool.

Thus, extensive modifications are called for if HEPA systems are to be installed in a residential HVAC. This usually happens when a home’s occupant has respiratory issues that require extremely clean air. Otherwise, most HEPA systems are found in clean rooms for research or technical work or in hospitals.

For the most part, a HEPA filter is usually found in an air purifier, which might be portable or whole-home. The filtration, which is very dense, can remove dust, pollen, mold, bacteria, and any airborne particles of 0.3 microns.

MERV-Rated Air Filters

HEPA and MERV filters operate differently, and the MERV rating system ranks filters according to their efficiency, with filters below MERV 8 having the least density so that they can only capture the largest particles. Low MERV usually indicates a flimsy fiberglass filter. Most home systems should use a filter between MERV 8 and 12, although 12 can slow down air somewhat. Although these higher MERV filters will trap more particles, if you notice that the unit is not cooling efficiently, you should probably try a less-dense filter. And, do change the filter according to the manufacturer’s recommendations.

For more on HEPA and MERV filters, contact Mowery Heating, Cooling and Plumbing, serving greater Indianapolis.