Non-Iterative Technique for Balancing an Air Distribution System


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Virginia Tech


Balancing an air distribution system consists primarily of measuring airflow and adjusting volume control devices to get specified airflow. Flow calculation methods are not accurate enough to ensure proper balancing by duct design alone. To assure proper balancing, dampers within an air distribution system must be adjusted until design flows are met throughout the system to within + 10%. By properly balancing an air distribution system, operating costs in the system will be reduced, comfort for the occupants in the building will be increased, and the life of the HVAC equipment will be improved.

Existing balancing techniques are iterative methods that require several measurements and damper adjustments. The flows and pressures are first measured, and then the dampers are adjusted to match design airflow. The flows are measured again and the measuring and adjusting process is repeated on a trial-and-error process until design flow is achieved. This iterative process is time consuming and expensive.

The proposed new balancing technique is to use a computer program that, based on a few measurements, determines damper adjustments that will achieve design airflow throughout the system. Each terminal damper is adjusted only once to a specified flowrate that is determined by the computer program, making the balancing process quicker and less expensive. No iteration is required.



HVAC, computer simulation, balancing technique