Furnace Air Filter In Grocery Store

[repairman54]

Lack of a protective grille over the filter in a customer area says it all IMO.

 

[Mazomopar]

Just flip it around. It'll clean it right out.

 

[Donald]

If you want a high quality furnace filter you need an Aprilaire media box installed and then use (expensive) Aprilaire filters. Not cheap, but probably the best filter out there