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Table 1. Setpoint Guidelines.
If the guidelines outlined in Table 1 are enforced, then
most issues encountered with minimum airflow
balancing at the minimum setpoint are removed.
However, there are some symptoms that may require
minor adjustments.
Erratic or Unstable Airflow or
Zero / “Invalid” Display After Balancing
Unstable Airflow at Low Velocities
Check the damper drive parameters. If there is a rapid
cycling of the sensed airflow, when the balancing is
completed, unexpected and large air balance value
swings can occur. If this is noted, an adjustment of the
damper drive parameters may be required.
Airflow
Setpoint
Rule
Maximum Maximum airflow setpoint cannot result in
a duct velocity greater than 3500 fpm
Maximum airflow setpoint must be greater
than the Minimum airflow setpoint
Minimum Minimum airflow setpoint cannot be set to
zero for balancing
Minimum airflow setpoint should be less
than or equal to 80% of the Maximum
airflow setpoint
