Furnace filters, part 2: filtration ratings

Self-tutoring about choosing a furnace filter: the tutor mentions filtration ratings.

I mention in my post from September 20, 2025 about replacing an old furnace filter with a fresh new one.

Besides physical dimensions, a furnace filter has another specification: the extent to which it removes particles as air passes through it. This might be known as its MERV rating, its FPR (filter performance rating), or even its MPR (microparticle performance rating). The websites I’ve visited seem to suggest that while professional installers think in terms of MERV, manufacturers have their own ways to measure filtration (such as MPR): 3M, for instance, uses MPR.

The filters I bought have MPR of 1000, which translates to MERV of 11. Professionals seem to suggest that MERV of 8 is very good for household purposes; beyond that is extra. However, too high a MERV might somewhat restrict the air flow to the furnace.

Such is my understanding. The furnace has been running a bit the past few mornings, and seems content:)

Source:

serviceexperts.ca

filtrete.com/3M