Do you have a central air conditioner in your home? If so, you may be wondering if it has two filters. The answer is yes! Most central air conditioning units have two or more filters. These filters are designed to clean the air and ensure good air quality as your unit circulates between indoor and outdoor air. Central air conditioning filters are usually made of fiberglass or pleated materials.
So why does your air conditioner have two filters? The answer lies in the size of your home and the number of HVAC systems you have. If you live in a large home, your system will most likely require more than one return air duct. And each duct requires a filter to stop particles before they reach the blower motor. Or, if you have several air conditioning units, the general rule of thumb is one filter for each air handler.
Most homes, especially large ones with multiple HVAC systems, have more than one air filter installed. They are usually placed near the oven or air conditioning system controller and return grilles. Larger homes often have more than one HVAC system. Each system will normally have at least one air filter. Therefore, your home may have air filters located in the air handling unit AND on returns.
You should check every possible location to make sure you have found all of your air filters. It may be that the cabinet is configured to accept a one- or two-inch filter. I would have to remove the side rails to insert a two inch size. It's important to note that a single good quality Merv 8 filter is enough for most homes. This is the filter recommended by the Department of Health, as it filters even the smallest particles, such as bacteria. When it comes time to change the filter, it's usually easy at the time of installation.
Placing some filters in an air purifier isn't likely to be significantly noticeable in electrical usage or motor voltage, but there is a mathematical impact (it's not free). There is usually not enough volume to keep dust in the air long enough for the air conditioner inlet to act as an air purifier. Placing two filters could temporarily address this issue, but it will have a negative impact on the CFM and, in fact, may require you to replace filters more frequently. It's common knowledge that you need to replace air filters regularly, and if you don't, damage and costly repairs often result in your HVAC system. Now that you know why you have 2 air filters in your HVAC system, let's identify where they are located.