It shouldn’t come as a surprise to you that 3M, the company that makes, well, everything, also makes furnace filters. Like most filter producers, they have multiple levels that fit different needs, but 3M opts to use its own rating system—Microparticle Performance Rating (MPR)—instead of the industry-standard MERV ratings. 3M makes great filters, but if you’re accustomed to MERV-rated filters, buying from 3M can cause some confusion. Let’s try to break it down.
MERV vs. MPR
Any filter rated on the MERV scale is rated based on its ability to capture medium to large particles that range from 1 to 10 microns and its ability to capture submicron particles that range from 0.3 to 1.0 micron. 3M filters focus strictly on the submicron particles, and they use a rating system called MPR. Some of those submicron particles include things like bacteria, smoke, and smog. The ability to capture a lot of those particles is pretty significant.
So you’re formerly a MERV person, and you’re switching to a 3M filter, or vice versa. Here’s a small guide of 3M’s filters and the way they relate to MERV:
Just like MERV ratings, the MPR system works on a scale. Higher MPR ratings work better than lower, and the higher MPR rated filters have a significant amount of media packed into their frames, as well as tighter pleats. They are built specifically to prevent anything other than clean air from passing through them, and they do a great job.
That said, the higher the MPR rating, the more expensive the filter will cost. And while these things are packed with media, they shouldn’t have much more of an effect on your HVAC system than what a similarly rated MERV filter would have. Airflow through filters is rated based on pressure drop—the lower the pressure drop number, the better the airflow, and all of 3M’s filters pressure drop numbers are in the “acceptable range.” While airflow won’t be overly restricted, your furnace will still be working hard to suck air, so don’t be surprised if you see your electric bills raise some, primarily if you’re used to MERV 1-4 or 5-9 filters.
3M also recommends that you change filters every three months. To be fair, most filter manufacturers suggest the same, but the density of some of these filters—especially once they become packed with tons of submicron particles—can put a significant damper on your furnace, as well as reduce efficiency.