The Nordic Pure 20x25x5 “MERV 12” Pleated Furnace Filter we had tested actually came out at MERV 7 (vs. the advertised MERV12).

With a permeability score of 9.71 (higher means better), this furnace & AC filter offers an excellent pressure-delta. The lower the pressure delta, the better your HVAC system would perform, which is probably why many HVAC installers would usually recommend this filter (vs. more restrictive air filters).

With a 6-12 months replacement frequency, the dust holding capacity of the Nordic Pure 20x25x5 “MERV 12” Pleated Furnace Filter is considered as high, which we quite like as more maintenance an HVAC system requires, the more likely it would end up being neglected altogether.

The filtration performance of the Nordic Pure 20x25x5 “MERV 12” Pleated Furnace Filter is poor at best. At the sub-micron level, this filter offers almost no protection (tested at 6% @ 0.3-1µm) and very low protection at the 1-3µm level (29%). The performance of this filter at the 3-10µm level is less-than-Ok (64.9%), however, Fltest.org does not incorporate this category into the weight of our scores.