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Clear the Air: Learn How Often to Change Furnace Filters

How often should I swap out my furnace filter, and which types of furnace filters are best?Change Furnace Filters

A furnace filter removes dust, dander and other large particulates from the air in our homes when either the furnace or central air conditioner is running, as the two systems share common ductwork for air distribution. Particulate buildup reduces a filter’s effectiveness and makes the fan work harder, shortening its life span. Both the furnace and air conditioner will operate less efficiently and may require more frequent servicing if the filter is too clogged.

The frequency at which you should change your furnace filter depends on the number of people who live in the home; how many furry pets reside indoors; the presence of smoke from tobacco, woodstoves or other sources; how dusty the environment is; the type of furnace filter; and the thickness of the filter.

If you have multiple fur-shedding pets, you live along a dusty road, or several smokers live in the residence, count on changing a 1-inch or 2-inch air filter every month. You’ll likely need to replace a 4-inch filter every two months and a 5-inch filter every three months.

If you have one pet, your home experiences only moderate dust accumulation, or no more than one smoker lives in the residence, filter replacement can shift to two, four and six months, respectively.

If the air in your home is mostly free of dust and completely free of pet dander and smoke, you can replace your filter just once per year.

Some filters are more efficient at filtering air than others. My advice is to buy washable furnace filters that offer the highest level of filtration. Make certain the filter fits exactly. Be sure to post a note on your calendar to remind yourself of how often to change furnace filters in your home. Check your filter every month for the first year after installation. If you find that your filter gets dirty faster than you anticipated, plan to replace it more often in the future.

Photo by Dreamstime/Luckydoor: Keep the air you breathe free of debris by regularly replacing filters.