Replacing your air filter in a timely fashion will help your HVAC system function more efficiently and prevent it from getting damaged. However, if you aren't sure what size air filter you need, you might choose the wrong size.
Luckily, there are three ways to determine which size air filter you need. In this guide, you’ll learn about all of them.
Look at Your Current Filter
When it's time to replace your air filter, the easiest way to determine which size you need is to look at what it says on your current filter. Air filters often have their dimensions printed somewhere along the sides. Your air filter might be a little dusty after being in use for a few months, so you might want to wipe it off with a rag or towel before you look.
Measure the Dimensions Yourself
If you've looked all over your air filter and don't see the dimensions written anywhere, it might be time for you to break out the measuring tape and find them yourself. You’ll need to take three measurements: length, width, and depth. Your measurements should be in inches, but if the measurements aren't whole numbers, you can purchase the "nominal size" instead of the "actual size."
Air filter manufacturers will cut their filters between an eighth of an inch and a quarter of an inch smaller than what they advertise, and these smaller dimensions make up the "nominal size." If your air filter is too big, it won't fit into your system. However, if the difference is that small, purchasing a nominal-size air filter shouldn't be a problem for your system, especially if you use high-quality products from Flanders filters distributors.
Check the Owner's Manual for Your HVAC System
This option should be a last resort if you don't have a tape measure or a ruler lying around the house. If you know where the owner's manual is for your HVAC system, you can refer to it for the recommended dimensions of the air filter. However, if you've lost track of the owner's manual, you can reach out to the manufacturer and let them know what the model number of your system is so that they can tell you the dimensions.
Overall, finding out your air filter's dimensions isn't rocket science. However, there’s more to it than you might think. Now that you know three ways to determine which size air filter you need, you'll never have to worry about buying the wrong filter ever again.
