Which duct system component connects a stack to a horizontal duct at a lower level?

The component that connects a stack to a horizontal duct at a lower level is known as a boot. A boot serves as a transition between vertical and horizontal airflow, allowing the duct system to properly direct conditioned air from the vertical stack to horizontal ductwork. This is crucial for maintaining efficient airflow and ensuring that air distribution is effective throughout the space served by the duct system.

The design of the boot is typically tapered, promoting smooth airflow and minimizing turbulence, which is essential for optimal system performance. When installed correctly, it helps in maintaining the desired air volume and temperature as it moves from the vertical to horizontal plane.