In the 29 years I've been in the HVAC business, I've seen a lot of washable "lifetime" "electrostatic" etc. filters come and go. My experience has been that they filter fairly well, because they are so thick, but this also causes them to be airflow restrictive. Which equates to making your unit less efficient. I currently recommend to customers the pleated filters that are available at most hardware stores, Wal-Marts, and many grocery stores. They come in a variety of grades and prices. For general household use, the $3to$5 filters are just fine, and will keep your unit clean for years when changed regularly. How regular you should change them depends on a variety of conditions in your house. In other words, how fast do they get dirty? If you have allergies, you may want to go with the higher dollar filters, and you may need to have your system cleaned also.If you have low airflow, it generally means dirt on the blower wheel blades, and the evaporater coil fins. From not changing filters enough. One more point. This #@$%! about a filter being more efficient when it gets dirty. A molocule of air will not pass through a molocule of dirt, so it goes around. When it can't find a place to go around, it pushes the dirt through. Why people try to see how long they can make a cheap filter last, instead of protecting an expensive piece of equipment is beyond me, but I make a lot of money off of folks like that. Same theory applies to the filters in your car.
GSD
