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Improved Air Volume Control Logic for VAV Systems
Abstract
In a VAV (variable air volume) system, the set
point of the static pressure (usually measured at 213
downstream of the main supply air duct) is
maintained by modulating the fan speed or inlet
guide vane position. The set point of the static
pressure is often set at a constant value, which is
adequate to provide design flow to each room. This
method consumes more fan power than necessary
under partial load conditions. The fan speed or inlet
guide vane can also be controlled based on the
maximum damper position of the terminal boxes.
This method is called air volume control logic.
Under this control logic, terminal box airflow
requirements are met with reduced static pressure.
Fan power consumption is minimized. However, the
actual system performance also depends on other
factors, such as inaccurate temperature or flow
sensors, faulty control valves, unbalanced loads, etc.
This paper discusses the existing air volume control
logic, its reliability and an improved air volume
control logic.
Citation
Wei, G.; Claridge, D. E.; Sakuri, Y.; M. Liu (2000). Improved Air Volume Control Logic for VAV Systems. Energy Systems Laboratory (http://esl.tamu.edu); Texas A&M University (http://www.tamu.edu). Available electronically from https : / /hdl .handle .net /1969 .1 /6793.