Model-based method for testing, adjusting and balancing of HVAC duct system

• Propose a model-based method for testing, adjusting and balancing (TAB).
• Design efficient measuring procedures to obtain data for model identification.
• Develop sequential tuning methods to set all dampers in proper positions.
• Balancing accuracy significantly exceeds the ASHRAE’s standard.
• The procedure is non-iterative, simple and easy to perform.

In this paper, an efficient method for testing, adjusting and balancing (TAB) of HVAC air duct system is proposed. The proposed method consists of three steps: 1) Establish the mathematical model for duct network; 2) Take pressure and flow rate measurements in the duct system to identify model parameters; 3) Calculate the balancing damper positions to achieve desired flow rates. The novel measuring procedure collects data efficiently, which makes this method practical. In case of no accurate damper position indicator, sequential damper adjustment according to airflow measurements is also proposed. Simulations and experiments have been conducted to validate the proposed method, where the final flow rates in all terminals match with the desired values with no more than 4.7% relative error in experiments. Comparing with existing TAB methods, the proposed method is 1) faster and more efficient by its non-iterative nature, 2) more accurate in balancing results, 3) easier and simpler to be performed, and 4) using flow meters and pressure sensors only. With these advantages, it is expected that the method will be accepted by HVAC industries.