Unless you have asthma or severe allergies, we usually recommend just buying the inexpensive furnace air filters at Home Depot, and changing them every month instead of every three months. Home Depot has a pretty big selection of air filters, so we thought we’d make it easy for you to find the filters we recommend for most people.
This picture shows what the air filters look like. They have green mesh in the middle, and a brown cardboard frame or border. At the time I’m writing this guide, you can get a pack of 5 of these filters for about $4
If you’re going to use these inexpensive filters, it’s important to remember to change the filter every month. Not every 3 months. You’ll still be saving money over buying the more expensive (and restrictive) filters that manufacturers recommend you change every 3 months. Not to mention you’ll have fewer problems with your heating and air conditioning system.