Air Filters

Air Filters



Usually carrying ratings of 1 to 4, flat-paneled fiberglass air filters consist of a disposable filter made of layered fiberglass fibers. A metal-like grating reinforces and supports the fiberglass material and helps prevent the filter from collapsing.

These inexpensive air filters mostly provide protection for heating and cooling components and not for cleaning the air. The filters have a medium efficiency rating for capturing larger airborne particles and a low efficiency for filtering dust mites, viruses, bacteria and dander.

Pleated media air filters: catch more particles than fiberglass

Similar to fiberglass filters, disposable pleated polyester filters have a sizable surface field and a rating of 5 to 13. The pleats increase the surface area and make the furnace filters more efficient at capturing airborne particles. A pleated air filter with a medium efficiency rating can filter small to large particles. Filters with a rating of 7 to 13 provide a level of effectiveness compatible with absolute high-efficiency particulate air (HEPA) filters, but at a lower price point.

HEPA air filters: best air quality control

HEPA filters are recognized by the Occupational Safety and Health Administration (OSHA) and EPA as the ultimate product for removing airborne particles. HEPA products filter air at a very fine level, blocking elements that are 0.3 microns or larger. These filters catch 99.97 percent of all particles. HEPA air filters have an efficiency rating of 17 to 20. However, most residential HVAC systems can’t accommodate HEPA filters because they are too large or restrict airflow. Switching to HEPA filters will significantly improve your indoor air quality, but doing so will probably require calling a heating and cooling professional to retrofit your system.

Washable air filters: reusable if properly maintained

Permanent and washable furnace filters are made from plastic or metal frames. These products have a few layers of polypropylene weave or wire mesh material that stops certain pollutants. The durability of the filtration material allows you to clean it and makes it reusable. Washable filters use static electricity to trap airborne particles. With proper maintenance, they are designed to be permanent filters.

However, washable air filters come with some drawbacks:

  • They’re usually rated only 1 to 4 on the MERV scale. “If your house is exposed to smaller particles like pet dander, cigar smoke or hair spray, a washable air filter may not be as effective as a higher-rated disposable filter,” Sinclair writes on his website
  • Maintenance is a pain. “Once you’ve washed them, you’re not supposed to simply dump the water out,” he writes. “Because that water was exposed to bacteria and other particulates, it’s considered a wastewater hazard and should be disposed of appropriately — creating extra work for you.
  • The filter can attract mold. When you wash these filters, they’ll take a long time to dry. If you re-install them while they’re still damp, they may develop fungi that your HVAC system can blow througout your home.
  • They cost more than a disposable filter. According to Sinclair, this means you’re paying more for a filter that requires a lot of maintenance.