Installation
Wiring specifications
To size output wiring, consider the following:
•
Total loop distance from the power supply to the controller, and then to the controlled device
NOTE
Include the total distance of actual wire. For 2-conductor wires, this is twice the cable length.
•
Acceptable voltage drop in the wire from the controller to the controlled device
•
Resistance (Ohms) of the chosen wire gauge
•
Maximum current (Amps) the controlled device requires to operate
Balancing the system using the i-Vu/Field Assistant applications
Most VAV system airflow designs are based on cooling requirements which require a greater cfm (liters/second)
flow than heating requirements. Using this balancing procedure, you will adjust the cooling airflow first. If the
heating and cooling maximum airflow requirements are the same, you will not need to balance the heating airflow.
NOTE
We recommend that the total heating minimum airflow settings for all the zones in the system be set to
maintain the air source’s design minimum heat cfm (liters/second) airflow across its heat exchanger to prevent
damage to the equipment.
The following procedures instruct you to use the i-Vu or Field Assistant application to balance the system.
However, you can also use the Test & Balance tool that includes global commands to assist you in balancing the
system.
Step 1: Prepare for balancing
1
Log in to the i-Vu application with an Administrator or Installer security level, or use Field Assistant.
2
Make sure the air source and its controller have been properly started and can run as a stand-alone unit.
3
Make sure all zone controllers have been addressed, commissioned, and started.
4
If a manual damper is installed upstream of the zone damper, verify that it is fully open before any balancing
occurs.
5
Verify that any zone controller supplying multiple diffusers has a manual balancing damper installed on each
duct for balancing the design airflow through each diffuser.
6
Disable the air source heating and cooling outputs using one of the following methods:
○
Physically disconnect the air source controller’s output wiring to the unit, then enable the fan.
○
In the i-Vu or Field Assistant tree, select the AHU controller. Go to
Properties
>
Equipment
tab
>
Equipment Enable/Disable
and enable
Test and Balance Command
.
7
Verify that the air source's supply static pressure setpoint is set to the system's design specification and that
it does maintain the setpoint.
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VAV Zone Controllers
