Changing the furnace filter protects your furnace and filters the air, improving the air quality in your home. Disposable furnace filters have either a mesh pattern or a pleated accordion pattern. Replace these filters once a month to keep your furnace running optimally. If your system handles both heating and cooling, replace the filter monthly all year long.

The filter catches the dust, dirt, pollen, carpet fibers, and pet dander in the air, which keeps the house cleaner and helps keep allergies at bay. It also keeps all that stuff from getting into the furnace, which helps the blower motor lasts longer and keeps compressor coils from clogging.


Locate the furnace filter compartment.

You can usually find it near where the cool air enters the furnace — the air return duct or at the entrance to the blower chamber. Sometimes there's a filter in both locations.


Slide out the old filter.

The filter should slide out easily. If there’s any resistance as you pull, check to make sure that there is a locking mechanism holding it in place. If so, slide the lock out of the way and it should slide right out.

Disposable furnace filters have a cardboard frame. If your filter has either a plastic frame or a metal one, stop here. It is a permanent filter and can be cleaned and reused instead.


Replace the filter with a new one.

Make sure you get the exact same size (the measurement is printed on the edge of the filter) and make sure that the airflow arrows on the side are pointing the right way (toward the blower and away from the cold air).

If you hate the thought of throwing away a filter every month, consider a permanent solution. Get a washable furnace filter instead. The permanent filter just needs to be taken out and rinse once a month. You'll save a bit of money and protect the environment.

You won't save money by not replacing filters regularly. You'd be surprised how much airborne crud gets into your house. Filters clog quickly, making your furnace work harder. When the furnace works harder, you use more energy and that means the heating your home costs more money!