Question: are all furnace filters the same?
Answer: Air filters are all the same. It's true! All air filters are not the same! ... Home HVAC air filters are graded by their MERV rating with most home filters falling between 1 and 13 (13+ are for HEPA filters). Spun fiberglass filters are the cheapest, minimum protection for HVAC equipment: 1-4 MERV.