Does a filter return air grill provide more "free air" compared to a regular return air grill?

To understand why the answer is considered false, it's essential to look at the mechanics of air flow in HVAC systems. A filter return air grill is designed to not only allow air to pass through but also to capture and filter out particulates, dust, and other airborne pollutants. This filtering mechanism can introduce resistance to airflow, which often results in a reduction in the overall volume of air that can be moved through the grill compared to a standard return air grill that lacks such filtering.

Regular return air grills are typically designed solely for the passage of air without any added components that could impede airflow, enabling them to provide a larger volume—often referred to as "free air." The fundamental difference lies in the operational design; filter grills need to accommodate filters, which can obstruct airflow more than non-filter grills.

While there are exceptions based on specific system configurations or conditions, the general principle holds that a grill with a filter will not allow as much free air as a plain return air grill, thus validating the conclusion that a filter return air grill does not provide more free air.