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U Line Airflow Control

u-flow icon
I/O Points microblock

The Airflow Control microblock accesses the airflow control algorithm available in U Line of control modules. This microblock provides inputs and outputs that communicate parameter and status values to and from the flow control algorithm.

This microblock is also used to access the built-in testing and balancing procedure that allows a VAV box to be commissioned through a LogiStat Zone Sensor.

The inputs in this microblock are used to determine the flow setpoint and minimum flow parameters; these are sent to the flow control algorithm. The algorithm opens or closes the dampers to maintain the actual measured flow at the desired setpoint.

To avoid damaging the damper actuator, the flow algorithm will not move the dampers for less than one second. If the required correction to the damper position requires less than a one-second movement of the dampers, no movement will be attempted. If the measured flow falls below the minimum flow parameter, however, the algorithm sends a one-second open signal to the dampers to ensure that the airflow into the zone does not fall below the required minimum. (This minimum flow provision is disabled if the minimum flow parameter is set to zero or if the flow setpoint is less than the minimum flow parameter.)

The number of damper movements (open or closed) per day is displayed on the control module driver Properties page. If this number becomes excessive, an alarm is generated.

Properties

NOTE  Alt+click any value in WebCTRL to view property details, including its expression and editing privilege.