The Aerostar “MERV 8” (we’ll get to that later) is a 1-inch deep pleated filter. The 20″x25″x1 version we tested contained 19 pleats. While this type of filter will fit most filter slots and housings, its performance is nothing to write home about.

With a permeability score of 7.3 (higher means better), the Aerostar MERV 8 furnace filter offers a relatively high pressure-delta. A higher pressure delta would put more strain on your furnace (or AC) blower fan, which would lead to higher consumption of energy and would potentially shorten the life of your equipment when compared to filters with a higher permeability score.

Most importantly, the filtration performance of the Aerostar MERV 8 filter at the sub-micron level is abysmal (3.2% @ 0.3-1µm) and pretty bad at the 1-3µm level (32%). The performance of this filter at the 3-10µm level is less than ok (65%), however, Fltest.org does not incorporate this category into the weight of our scores. It is worth mentioning that when we tested it, its MERV rating came out at 7 (vs. the advertised 8).

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