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?

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.