04/14/2022
What Does a Furnace Filter Do?
Your furnace filter traps airborne contaminants to clean your air, right? While yes, it does do that, that’s not exactly its job. The primary function of a furnace filter is to trap airborne contaminants not for air quality purposes, but to keep them out of your heating and cooling system.
Changing furnace filters is a job that’s frequency varies from one house to the next. How often this task needs to be performed is dependent on the type of furnace filter being used.
Changing furnace filters needs to be completed every month to every year – just like there is a great range of filters, there’s a pretty wide range to how often they need to be replaced.
To give you a starting point for what frequency you’re looking at for changing furnace filters, size matters. Thicker filters have more media available to capture contaminants, so a 5-inch filter requires less frequent changes than a 1-inch filter.
In general, this is how often changing furnace filters needs to be done:
For 1- to 2-inch filters, replace them every 1 to 3 months
For 3- to 4-inch filters, replace them every 6 to 9 months
For 5- to 6-inch filters, replace them every 9 to 12 months
More Factors that Affect Frequency of Changing Furnace Filters
Home Occupancy
The number of people living in a home affects the useful service life of a furnace filter. In a large household, changing furnace filters is done on a more frequent basis than homes with just one or two occupants. People introduce many contaminants to the home environment, so the more people there are in your home, the more contaminants there are for the filter to catch.
Furry Family Members
Pets are another major contributor of contaminants into the indoor air supply. Pets shed fur and dander, which are picked up by airflow and circulated throughout the home by the HVAC system. For every furry family member living in your home, a filter’s useful service life is reduced by approximately 30 days, so you’re changing furnace filters more often.
Indoor Air Quality
If you have air quality issues present in the home, your furnace filter isn’t going to last as long as it does in a home with good indoor air quality. Indoor air quality equipment like air purifiers and air cleaners reduce contaminant volume so there’s fewer particles for your furnace filter to capture – in homes without this equipment, the furnace filter is the only line of defense against airborne contaminants, so the filter fills up faster.
Allergies
If members of your household suffer from allergies or asthma, changing furnace filters should be done on a more frequent basis. Doing so helps ensure contaminants that cause symptoms are removed from your indoor air supply.
Heating & Cooling Usage
When your home’s heating and cooling equipment is heavily operated, filters have a shorter useful service life – air is circulated more frequently, so the filter has more opportunities to pick up contaminants and become clogged. In the summer and winter, homeowners are typically changing furnace filters more often than they are in the fall and spring.