Residential HVAC Installation Practice Exam

A reducing plenum in a duct system serves the purpose of reducing the size of the ductwork as it comes off the main plenum. This is important because it allows for a gradual reduction in duct size to match the airflow requirements of the individual branches or rooms in the building. By tapering down the size of the ductwork, the reducing plenum helps to maintain proper air velocity and pressure throughout the system, ultimately ensuring efficient and effective HVAC operation. Options A, B, and C are incorrect because a reducing plenum is specifically designed to decrease the size of the ductwork and is not primarily intended to increase airflow pressure, reduce noise levels, or uniformly distribute air to the ducts.