When and How to Change Your Furnace Filter

December 01, 2015

Maintaining your furnace can help more than you’d think in the period in between furnace service appointments. One of the easiest, and essential, ways to maintain your furnace is in switching out your furnace filter. Having a dirty air filter could contribute to a variety of adverse issues for your heating and cooling system, its efficiency, and ultimately, how much your energy expenses are month after month.

So what goes in to deciding when you should change your furnace filter?

  • Type of filter: the two most common filter sizes are 1 inch and 3 inch filters. 1 inch filters normally need to be switched out every month and 3 inch filters need to be swapped out every three months, based on the recommendations of the filter manufacturer.
  • Home habits: if you have pets in your home, it may make sense to change your filter more often due to pet dander. If you have someone in the house that deals with allergies or asthma, contemplate changing your home’s air filter more regularly to help ease their symptoms.

Now you’re possibly wondering how to replace your furnace filter. Inevitably this will change depending on what furnace you have, but typically: 

  • Open or pull off the air filter panel around the bottom of your furnace to reveal an open compartment.
  • On the top of that open compartment is where you’ll see your furnace filter resting on two metal supports.
  • There will be a small amount of space to move your filter back and forth that allows you to bring down one end of the filter and pull it out of the compartment.
  • When installing the new filter, look at the perimeter of the filter for an arrow that indicates the air flow direction, to make sure you’re installing the filter in the right direction. In most cases, the arrow should point at the main part (or top) of the furnace. 
At San Antonio Air Service Experts, we’ll replace standard one-inch furnace filters as part of our regular furnace service Precision Tune-up or PLUS Maintenance Agreement service. Give us a call today at or arrange an appointment with us online.