Pickup Gain Calculations (Flow Calculation) - Johnson Controls - Metasys - LIT-12011147 - Software Application - Controller Configuration Tool - 15.0

Controller Tool Help
Product
Controls > Control Tools > Controller Configuration Tool
Document type
User Guide
Document number
LIT-12011147
Version
15.0
Revision date
2022-11-18

About this task

For single point calibration, Pickup Gain 2 is set to zero and Pickup Gain is calculated using the following equation:

When using two-point calibration, calculate the Pickup Gain values using the following procedures and equations:

Note: You must balance the VAV box manually instead of using the balancing feature.

Procedure

  1. In Commissioning mode, view details of the Supply Flow Calculation module.
  2. Record the current value of Pickup Gain as PGoriginal.
  3. If not set to zero, set Pickup Gain 2 to zero.
  4. Override the flow setpoint to the desired minimum flow and allow the flow controller to stabilize.
  5. Record the SA-F value that appears as MinFlowController.
  6. Record the Differential Pressure value that appears as EffDPminflow.
  7. Record the airflow measured using a hood as MinFlowHood.
  8. Override the flow setpoint to the desired maximum flow and allow the flow controller to stabilize.
  9. Record the SA-F value that appears as MaxFlowController.
  10. Record the Differential Pressure value that appears as EffDPmaxflow.
  11. Record the airflow measured using a hood as MaxFlowHood.
  12. Calculate the PGminflow and PGmaxflow using the following equations:
  13. Calculate PG2 and PGnew using the following equations, where
    • PGnew is the new Pickup Gain to enter in the Balancer Override module
    • PG2 is the Pickup Gain 2 to enter into the Flow Calculation module
  14. View details of the Balancer Override SD module and click Edit.
  15. In the SA-KFACTOR field, enter the value calculated for PGnew.
  16. Click Apply and then click Close.
  17. View details of the Flow Calculation module and click Edit.
  18. In the Pickup Gain 2 field, enter the value calculated for PG2.
  19. Click Apply and then click Close.

    The Flow Calculation module uses the following equation to calculate flow: