Are the more expensive home air filters (for heat & a/c) worth the extra money?

’ ’Ya pays your money & ’ya takes your choice Are the "30 day" filters "just as effective?" No. They are basically a very tiny string of molten glass that is forced out of a tiny orifice and goes back and forth in a random pattern until just about all of the space between strands is filled up. So right away the size of the hole the air gets through between the glass fibers is larger than the more expensive pleated filters that are made out of a non-woven polyproplyene fabric with much smaller holes for the air to get through. This smaller-hole-filter keeps from restricting the air flow too much by having pleats that increase the surface area that the air can pass through. The larger holes on the inexpensive filter allows more mold spores, pet-hair dander, pollen, and dust to pass through--thich is why in the trade they’re referred to as "gravel strainers--because comparativey speaking all they do is "strain out the gravel." Even so, though, they are better than nothing (that is, ...  more