If you’ve spent any time at the store and browsed the filter section, you probably have come across these ratings: MERV or FPR (at Home Depot) and MPR. What do these mean? Well, each of them actually stand for something slightly different but essentially mean the same thing.
Here's a snapshot of what they mean:
MERV, or Minimum Efficiency Reporting Value is the primary rating for filters in the HVAC industry both domestically and internationally. Established by the American Society of Heating in 1987, it was created to measure the effectiveness of air filters.
MPR, or Micro-Particle Performance Rating similar to MERV, is a system that rates filters based on their ability to capture airborne particles, but the difference is that the particles must be smaller than 1 micron, (or a unit of length equal to one millionth of a meter (3.28 feet) )
FPR, or Filter Performance Rating is a system that specifically developed for The Home Depot (developed by 3M) and only pertains to the brands that are sold in their stores. The rating system is actually similar to MERV.
MERV vs. MPR/FPR at a glance:
If you think this is all you need to know, it gets more complex than this. But for sanity's sake, we'll keep this breakdown simple.
While the above image shows you what the filters block out, what it doesn't explain is what works best for your home. Though there is a calculation involving the tonnage of your unit and figuring out the CFM (cubic feet per minute) and maximizing air flow in your ducts, (ducts size, return vents and space, etc.) we wanted to focus on something that would be slightly easier to comprehend rather than throwing HVAC jargon at you.
If you look at most higher end filters, they have a tighter weave in the pleats. The logical choice (according to the chart) is to find a better filter with a higher MERV rating. A higher MERV rating improves filtration effectiveness by trapping more particles─ which is why a tighter weave is more effective.
The tighter pleats, look like this:
While you would think this would end the discussion and you would just go out and buy a filter with a MERV rating of 13─ think again. If you were to use a MERV 13 in most residential homes, that would mean you would have to change your filters out every week!
However, in retrospect, if you have a filter that looks like this:
You would probably be replacing it at the same rate, but it would filter out virtually nothing.
That seems silly, doesn't it? Paying for either something that would filter extremely well (MERV 13), but have to be replaced once a week, or barely filter anything. The highest MERV rating also causes static pressure issues in your home and can over-work your system. It is not meant for most residential units.
Stick to MERV ratings of 8 and 11, or MPR 600 - 1200 and FPR of 5 or 7.
The pleated surface and weave of these filters allow enough air flow, and relieves pressure so that you are receiving the maximum air flow and capturing 70% or more of the particles coming into your home─ leading to a more healthy environment and improving your quality of life, without putting a huge dent in your wallet!