Your furnace comes equipped with an air filter that’s usually found at the point where the return air duct connects to the furnace cabinet where the blower fan is located. Sometimes the filter is behind the vent cover of the return air vent. If the cabinet contains both the furnace and the air conditioner, the systems will use the same filter, which is why the filter is sometimes called the HVAC filter.
You might assume that this filter’s primary purpose is to help provide cleaner, healthier air for the house. After all, why else have a filter in place? The truth is different, however. Although the furnace filter can provide some minor benefit to your home’s indoor air quality, this isn’t what it is designed to do. If you’re looking for better indoor air quality, you can’t rely on the filter and may need to look into other options.