--- title: "What You Might Not Know About HVAC Filters" description: "Everyone agrees that you should change your HVAC filter on a regular basis, but not everyone agrees on the type of filter you should use." date: "2012-07-26" modified: "2018-07-20" authors: - name: "Joe Provey" job_title: "Contributing Writer" link: "https://www.bobvila.com/authors/joe-provey/" url: "https://www.bobvila.com/articles/what-you-might-not-know-about-hvac-filters/" categories: - "Heating & Cooling" - "Interior" tags: - "air quality" - "Furnaces & Boilers" - "heating" - "hvac" - "maintenance" --- # What You Might Not Know About HVAC Filters ![HVAC-Filter-Make-Your-Own-Kit]() *Photo: JProvey* Everyone agrees that you should change your HVAC filter on a regular basis, but not everyone agrees on the type of filter you should use. Next time you go shopping for a furnace (or AC) filter, here are a few things to keep in mind. These tips can save you a bundle and perhaps even prevent you from inadvertently damaging your HVAC equipment. The primary purpose of a filter is to protect HVAC equipment, not to improve indoor air quality, as many homeowners have been led to believe. Many furnace manufacturers recommend that you use a low-cost fiberglass filter, but when I asked a representative of one major maker, his response was "no comment." Perhaps this was because high-efficiency filters that are *too* good may actually slow airflow across the heat exchanger, reducing the unit's efficiency, raising your energy bills, and causing furnace damage due to overheating. Similarly, a high-efficiency filter can freeze the condensing coils on an AC unit. (A dirty filter can do the same thing.) Even more of a shocker is that furnace filters do relatively little to reduce the number of small particles you inhale. That’s because these particles tend to be in the air wherever there is human activity—and that’s not necessarily where your return registers and ductwork can capture them, according to research by the Canada Housing and Mortgage Corporation ([CHMC]()). In addition, furnaces (and central ACs) run only seasonally. Even during the heating and cooling seasons, furnaces run only part of the time. So it stands to reason they are not filtering the air when the fan is not running. ![HVAC Filter Kits]() *Washable electrostatic filters are available in several standard sizes, as well as kits.* Want to save money and stop wasting time trying to figure out conflicting furnace filter maker ratings systems? Make your next filter a permanent electrostatic filter (also known as a washable one). The kit I tried is available online and can be cut to fit most filter cabinets. Washable filters may be reused for 5 to 10 years and cost about $20 each. These filters should be rinsed once a month and prior to re-installation, they should be allowed to dry. Some permanent electrostatic filters include carbon filtration for odor removal. Keep in mind that electrostatic filters are most effective when new and clean, so they should be washed frequently. Pre-made sizes are limited, but some manufacturers, such as [WebProducts](), will fabricate filters to your specs for about $35 each. ## Author Joe Provey is an expert on all things home and garden. His work has appeared in many national magazines, including [Popular Mechanics](), [House Beautiful](), [Better Homes & Gardens](), and [Fine Homebuilding](). Mr. Provey has also written more than dozen books, including [*Convert Your Home to Solar Energy*]() and [*1001 Ideas for Kitchen Organization*]()*.* Other titles include *Outdoor Kitchens, Easy Closets, Green-up Your Cleanup, and Design Ideas for Flooring.* Currently, Mr. Provey serves as the president of Home & Garden Editorial Services (HGES), a company that produces books for publishers in the home and garden category. In the past, he has been chief editor to several national home improvement magazines, including [The Family Handyman](), Mechanix Illustrated, and Practical Homeowner. Joe lives in Bridgeport, Connecticut, with his wife MaryAnn, where they have seven children and four grandchildren between them. ### Author social links [LinkedIn]()