Issue
Procedure for balancing a parallel fan VAV box with supply side flow sensing, using the WorkPlace Flow Balance Tool (WFBT).
Product Line
TAC IA Series
Environment
I/A Series MNB VAV
Cause
Request from field
Resolution
In summary, the procedure is to complete the balancing process with the fan disabled then enable the fan and use the verify functions to check operation with the parallel fan running.
- Perform all steps of the flow balance procedure as usual up through and including the maximum flow balancing and minimum flow balancing.
- For the first pass at balancing the reheat minimum flow, use the fan control on the screen to turn the fan ON then set the minimum flow setpoint to 0. Verify that the flow as measured by the pressure sensor goes to zero.
- Measure the total flow manually using the flow hood and adjust the fan speed so that the required airflow is obtained. The easiest way to do this is to take the first set of readings from all the diffusers then adjust the fan speed as needed and then recheck the sum of the new readings to confirm the adjustment is correct.
- Click the "Restart" button to restart the Reheat Min Flow balancing process.
- Set the parallel fan to OFF and re-enter the desired Reheat Min Flow setpoint value.
- Balance the Reheat Min Flow using the normal balance procedure.
For reference, see Chapter 5 of the WorkPlace Commissioning Tool and Flow Balance Tool Users Guide (F-27358).
