Nate Core Practice Test 2025 - Free Practice Questions and Study Guide

A backdraft damper performs a critical function in an HVAC system by preventing outside air from entering the building when the system is off. This is particularly important for maintaining indoor air quality and energy efficiency. When the HVAC system is inactive, the damper closes, creating a barrier that blocks outside air, which can contain contaminants or pollutants, from seeping into the indoor environment. By doing so, it helps to maintain a controlled indoor atmosphere, keeps conditioned air from escaping, and reduces the workload on the HVAC system when it is operational, ultimately improving overall efficiency and comfort.

The other options refer to functions that are not relevant to the role of a backdraft damper. While fresh air circulation is important for indoor air quality, it is typically managed by other components in the HVAC system, rather than through a backdraft damper, which is more focused on preventing unwanted air entry. Even heat distribution is managed through ductwork and vents without the necessity of a backdraft damper. Additionally, the regulation of refrigerant temperature is handled by specific components such as expansion valves and compressors, not by damper systems.