46 AGR 055A through 100A IOMM AGR
UNT Controller Operation
This section provides setup and troubleshooting information for the Global UNT controller.
All operational descriptions are based on the Global UNT software SURE4-2A. Operational
characteristics may vary with other versions of software.
General Description
The Global UNT is a microprocessor based leaving water controller designed for multiple stage
operation.
The Global UNT’s operation is based on an adjustable setpoint and control band. Controller
software is available for different reset options, refrigerants and metric units. Optional equipment
includes a Zone Terminal that can be installed in the unit or remotely. The Zone Terminal provides
a user interface to all reset options and adjusts specific setpoints. Downloading of software or
changing selected operating parameters requires the Global UNT Interface Kit.
Optional Sensors
• Return water temperature sensor
• Zone temperature sensor
Sensors and Transducers
Sensors and transducers are mounted and connected to the Global UNT controller with sensor cable.
The evaporator pressure transducers depress the Schrader fittings and can be replaced without
pumping the unit down. The pressure transducers are connected to the Global UNT controller
analog inputs with IDC connectors (Insulation Displacement Connectors). The low pressure
transducers have a blue dot. The leaving water sensor is in a thermal well for easy replacement
without draining the water system. As standard, an outside air sensor is provided on the back of the
control box. When other reset options are selected, the outside air sensor is not provided as only one
(1) type of reset is available.
Control Wiring
Low voltage control wiring is installed, labeled and tested by the factory before shipment.
External Voltage Inputs
The signal for remote reset option (2 to 10 Vdc) or demand limit (0 to 10 Vdc) is provided by the
installing contractor. Connect to TB -7 terminals #134 (+) and #135 (-) as indicated by the unit
wiring diagram. A 4 to 20mA signal conditioned by a 500 ohm resistor can provide the 2 to 10 Vdc
input for the remote reset option. Polarity of the external DC signal must match the controller
polarity.
Interlock Wiring
All interlock wiring to field devices (such as a flow switch or time clock) is provided by the
installing contractor. All interlocking wiring must be connected to the Global UNT 24Vac power
supply. External power supplies connected to the Global UNT controller can damage the controller.
See unit wiring diagram.
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