How Often Should I Change My Furnace Filter?

Posted Apr 7, 2017

Most experts recommend changing furnace filters between once a month and every three to six months. Several factors will determine how often consumers need to change their furnace filters. Since households are different, changing the furnace filter will vary depending on lifestyle choices. For example, large families with several cats and dogs or those with a smokers may need to change their filters more regularly than two-person households with no pets. If someone in the house has allergies or respiratory conditions such as asthma, it may be necessary to change the filters more frequently. However, the type of filter- fiberglass or high-efficiency – is the most important factor to consider when determining how often it should be changed.

Fiberglass filters


Traditionally, experts have recommended changing furnace filters at least once a month. Traditional filters are made from fiberglass. These filters are porous and built to block large particles that could cause damage to the furnace. They are not manufactured to block smaller particles that could irritate a person’s respiratory system.

Although experts recommend changing traditional filters monthly, fortunately, if consumers forget to change them every month, in most cases, the heating system will continue to function properly. The dirt trapped on the fiberglass fibers actually increases the filter’s ability to prevent small particles from entering the furnace.

High efficiency filters


Recently manufacturers have begun marketing high-efficiency filters. These filters are pleated in a zigzag pattern and they have built in electrostatic charges. According to laboratory tests, these filters remove up to 90 percent of pet dander and mold spores. Also, the electrostatic charge magnetizes micro-particles. Particles from viruses, bacteria, soot, and smoke position themselves in the lungs and cause respiratory and other health problems. Manufactures suggest changing high-efficiency filters every three to six months.

Unlike traditional filters, if high-efficiency filters are not changed, it may become costly. The filters become clogged and air flow is restricted. Once this occurs the furnace cannot properly circulate air. As a result, the blower has to work harder and run longer to heat the home. This may cause an increase in gas or electric bills. And eventually damage the furnace.

To prevent furnace damage and respiratory complications, consumers should change their filters according to the manufacturer’s specifications, regardless of the type of filter they have.

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