Which furnace or air conditioner filter should I buy?

People often write to us asking if we can tell them which filter to use with their furnace or air conditioner. The short answer is: "I'm sorry, but we don't have that information."

We usually provide a slightly longer answer as well, which goes something like this: "That's a really hard question to answer. Manufacturers often change the furnace filter that they use for a particular furnace or air conditioner model over time. The best way to find out is to check the user's manual that came with your unit. If you no longer have the user's manual, you can check directly with the manufacturer."

If you have more questions about furnace filters, please visit our furnace filters homepage.