A balancing damper is a manually adjustable blade device installed in ductwork to regulate airflow distribution and equalize pressure across multiple branches or zones. These static dampers enable field adjustment of system air volumes without replacing ducts or modifying equipment, making them essential for commissioning and seasonal adjustments.
Function and Installation
Balancing dampers contain multiple parallel blades rotatable from 0 to 90 degrees to throttle airflow. Installed perpendicular to airflow direction, they create measurable pressure drops ranging from 0.1 to 1.0 inches of water column at design velocity. Proper placement requires installation at least 10 duct diameters downstream of supply fans to ensure accurate reading and steady flow conditions.
Commissioning and Adjustment
HVAC technicians use calibrated balancing dampers with anemometers or pitot tubes to measure CFM across branches and achieve design airflow distribution. Locking handles or stops prevent accidental repositioning after commissioning. Color-coded position indicators show damper settings. Regular inspection ensures damper slides move freely without binding from dust accumulation or corrosion.