VAV Airflow Setpoint Tracking

VAV Airflow Setpoint Tracking

This workflow will test a VAV box for its ability to follow the Discharge Airflow Setpoint. 

  1. First, you will see the equipment’s preconditions. 

  2. Then, KODE runs a precondition check (verification process) to ensure (confirm) the equipment is ready for testing. 

  3. Finally, KODE adjusts the setpoints and monitors discharge airflow to determine if the VAV archives the intended setpoint. 


Outcome 🎯

This test will identify issues with a VAV ability to follow airflow.

Recommended Schedule 📅

Run weekly per floor. 


Device 

Point Requirements 📌

VAV

Occupied Mode

Discharge Airflow

Discharge Airflow Setpoint

Min Occ Cooling Flow

Max Occ Cooling Flow

AHU

Discharge Air Pressure


*Variations: There is a variant of this workflow that will work without the AHU requirement.

Workflow Overview


Test Step

Workflow

1

Pre-condition Check

  1. VAV is Occupied

  2. AHU Pressure > Min Pressure Threshold

2

Airflow SP - 1

  1. Control: Command Airflow Setpoint

  2. Success: Airflow in range of setpoint +/- tolerance

3

Airflow SP - 2

  1. Control: Command Airflow Setpoint

  2. Success: Airflow in range of setpoint +/- tolerance

4

Airflow SP - 3

  1. Control: Command Airflow Setpoint

  2. Success: Airflow in range of setpoint +/- tolerance

5

Airflow SP - 4

  1. Control: Command Airflow Setpoint

  2. Success: Airflow in range of setpoint +/- tolerance

6

Min Sequence Duration

What is the minimum length of time in seconds that a sequence should take to execute?

Tuning Parameters


Test Step

Result Description

1

AHU Min Pressure

If AHU Pressure is less than this number, the test automatically archives

2

Airflow SP - 1

What % of the Max Occ Cooling Flow do you want to set as the first target?

3

Airflow SP - 2

What % of the Max Occ Cooling Flow do you want to set as the second target?

4

Airflow SP - 3

What % of the Max Occ Cooling Flow do you want to set as the third target?

5

Airflow SP - 4

What % of the Max Occ Cooling Flow do you want to set as the fourth target?

6

SP Tolerance %

How close should the airflow be to the airflow setpoint to pass?

7

Max Sequence Duration

What is the maximum length of time in seconds that a sequence should take to execute?

8

Min Sequence Duration

What is the minimum length of time in seconds that a sequence should take to execute?

9

Stabilization Time

How long in seconds should the program wait when one sequence finishes, before moving onto the next?


Common Reasons for Unsuccessful Tests


Reason

Description

1

Check and Adjust Calibration

Begin by verifying the calibration of all sensors involved in the test, especially the discharge airflow sensors and pressure transducers in the AHU. Calibration issues can lead to inaccurate readings that cause the system to deviate from the setpoint. If any sensors are found to be out of calibration, recalibrate them according to the manufacturer's specifications before rerunning the test.


2

Inspect VAV and AHU Components

Examine the physical condition of the VAV box and associated AHU components. Check for any signs of damage or wear that could affect performance, such as stuck dampers, leaks in the ductwork, or malfunctioning actuators. If any issues are found, perform the necessary repairs or replacements. Ensure all components are clean and free from obstructions that could impair airflow.

3

Review System Configuration and Sequencing

Evaluate the VAV box programming and configuration settings. Confirm that the airflow setpoints, sequence durations, and stabilization times are correctly set according to the operational requirements. Adjust the control sequences if needed to ensure they align with the current operational strategy and performance expectations. It may also be helpful to consult with a control specialist to optimize the sequence of operations for better performance.


If you need assistance with interpreting your results, reach out to the support team at [email protected]. 



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