What is the purpose of a balancing damper in a duct system?

The purpose of a balancing damper in a duct system is to regulate the airflow to different zones or branches of the ductwork to ensure proper air distribution throughout the building. Balancing dampers are manually adjustable dampers installed in the ductwork that can be used to increase or decrease the airflow to specific areas. This is necessary because duct systems often have variations in airflow due to factors such as duct length, duct size, and fitting losses. Without balancing dampers, some areas may receive too much airflow while others may receive too little, leading to comfort issues and inefficient system operation. By adjusting the balancing dampers, HVAC technicians can ensure that each zone receives the correct amount of airflow as specified in the design. This process is known as air balancing and is typically performed during the commissioning of a new HVAC system or after modifications to an existing system. For example, if one branch of a duct system is receiving more airflow than designed, the balancing damper on that branch can be partially closed to reduce the airflow to the desired level. Conversely, if another branch is receiving too little airflow, the balancing damper can be opened further to increase the airflow. Proper air balancing is essential for achieving optimal comfort, energy efficiency, and indoor air quality.