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How to

How to


Products: Commission, MP-V
Functionalities: Engineering, BACnet/IP devices
Product version: 2023, 2024
12/17/2022

Flow Balancing at Minimum, Intermediate, or Maximum Flow Setpoint

Using the Commission mobile application, you flow balance a VAV unit at each designated setpoint to achieve the desired air flow.

You can select one, two, or three flow setpoints for flow balancing. The minimum flow setpoint is selected by default. In addition, you can also select the intermediate flow setpoint.

Important:

In the Air Balancing Setpoints view, the Intermediate flow setpoint check box is cleared by default. However, it is recommended that you include this setpoint for flow balancing. While the maximum setpoint does not have a check-box, it is still mandatory that you include that setpoint too. Doing so allows you to achieve greater flow accuracy across the operating flow range of the VAV unit.

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The Flow Balance function of the Commission mobile application is used to air balance terminal boxes controlled by a VAV controller. This function automates most of the air balance procedure but it also allows you to manually check out the flow balance by driving the damper to a specified position, a flow setpoint, or a flow value.

Flow balancing, also known as air balancing, is the process you use to calibrate an installed VAV terminal unit so that the airflow indicated by the VAV controller is accurate, relative to the true airflow delivered by the VAV terminal unit.

After the Electrician installs, wires, and powers the VAV controller, the controller automatically calibrates the damper stroke. Upon start-up, the VAV controller will automatically perform a damper stroke angle calibration where the damper rotates to each mechanical end stop. After the VAV controller has completed this process, it is ready to be accessed from the Commission mobile application to perform flow balancing.

When you select an VAV controller from the Commission mobile application, a Variable Air Volume Data object is automatically created in the controller. This object has values that read the Airflow Sensor terminal and values that configure the Damper Control 1 of the VAV controller. The VAV controller also contains logic to assist in the flow balancing calibration.

For more information, see Commission Mobile Application Overview .

Note:

The Commission mobile application supports flow balancing for VAV controllers with the data object Variable Air Volume only. The Commission mobile application does not support flow balancing for VAV controllers with custom balancing programs.

Flow Balancing Workflow

Use this workflow to perform flow balance on a single VAV controller controller, using the Commission mobile application. Related information can be found in the section after the flowchart. For more information, see Flow Balancer Workflow .

Configure Setpoints

You configure the VAV controller controller setpoints to prepare the parameters by which the controller is balanced. These setpoints include the maximum flow setpoint, selected by default, and the intermediate and minimum flow setpoints, which are optional. For more information, see Configuring VAV Controller Setpoints .

Flow Balance at Setpoints

Using the Commission mobile application, you flow balance a VAV unit at each designated setpoint to achieve the desired air flow.

For more information, see Flow Balancing at Minimum, Intermediate, or Maximum Flow Setpoint .

Perform Manual Checkout

After completing the automated flow balancing process, you can use manual checkout to verify and command the air flow values for one or multiple VAV controllers.

For more information, see Performing Manual Checkout of Air Flow .

Verify Damper Rotation

You can manually verify the direction of the damper rotation of an VAV controller to verify that the actuator rotates clockwise or counterclockwise to open.

For more information, see Manually Verifying the Direction of Damper Rotation .

Flow Balance Reports

The Commission mobile application provides the user with a means to generate a flow balance report that documents several values:

  • Box capacity at 1 inch H20 (249 Pa)

  • Box measured flow

  • Hood measured flow for each setpoint used during balancing

  • Actuator stroke and rotation

  • Flow balance time and date

  • Any comments

Using the Commission mobile application, you can create, append, and delete flow balance reports. Flow balance reports are stored on the Commission mobile application mobile device and can be retrieved and shared using the file and e-mail applications of that mobile device or Windows 10 laptop.

For more information, see Flow Balance Reports .

To flow balance at the minimum, intermediate, or maximum flow setpoint

  1. In the Commission mobile application, on the Device Settings page, click Flow Balancing .

  2. In the Air Balancing Setpoints page, notice the checkbox next to the Minimum flow box.

  3. Enter setpoint values for the Minimum flow , Intermediate flow , Maximum flow and click Next .

    The Commission mobile application issues a message and then checks to ensure that the damper is in the closed position before calculating the velocity pressure offset . If it is not currently closed, it waits to close.

    The offset is calculated at this point in the flow balance process to address any potentially significant velocity pressure zero offset errors. Such errors may interfere with flow control near minimum flow setpoints.

    The velocity pressure offset is then calculated by averaging 20 sample readings.

    Tip:

    To skip the velocity pressure offset reading, click the Bypass velocity pressure offset box on the Setpoints page . If you have a large number of VAV boxes to balance, this process can be time-consuming, so you may wish bypass it as needed.

  4. After the offset calculation is complete, click Yes to accept the change and write the value to the controller and proceed.

  5. Click No to disregard the zero offset calculation.

    The application now goes ahead and calculates the minimum, intermediate, and maximum flow setpoints.

Once those calculations are complete, the VAV unit is flow balanced at the selected setpoints. Now you are ready to perform manual checkout.

See Also

  • Flow Balancer Workflow
  • Flow Balancing
  • Configuring VAV Controller Setpoints
  • Performing Manual Checkout of Air Flow