Operating instructions

52 IMM AGSB-60
Optional Features
There are a number of options that may or may not be present on any specific unit. These
options can affect unit control operation and how a unit is installed and wired.
Controls
Low Ambient Head Pressure Control
Optional VFD head pressure control on first two fans permits unit operation down to 0°F
(-18°C) ambient (balance of fans are staged on and off). However, since the actual minimum
ambient can be dependent on wind conditions, wind baffles are also available. Selection of
this option also requires the addition of the High Ambient Option to provide a heat dissipation
means for the VFDs.
Ice Storage
The unit is equipped with control logic to handle the low temperatures associated with thermal
storage applications. Additional evaporator insulation is recommended.
Water Flow Switch
(Part Number 01750330) A water flow switch is available for field installation in the chilled
water piping to protect against evaporator freeze-up under low or no flow conditions.
Terminals are provided in the control center for circuit #1 for field wiring of the water flow
switch to the unit. NOTE: Installation of a flow detection device is required.
High Ambient Operation
Option required for operation at ambient temperatures above 115°F (46°C) or when the unit is
equipped with the VFD low ambient fan control option. The kit includes a thermostat
controlled, panel ventilation fan and inlet grille with filter. The option can be ordered with any
unit. Ordering a “High Efficiency” unit does not automatically include this kit, it must be
ordered separately. Compressor loading and unloading is adaptively determined by system
load, ambient air temperature and other inputs to the MicroTech II control algorithms.
Building Automation System (BAS) Interface
This is the Protocol Selectability® option to the MicroTech II controller. The addition of this
optional communications module to the standard unit controller enables the controller to
communicate using standard protocols such as L
ONTALK®, Modbus® and BACnet® using
any of the following data link layer options: BACnet MS/TP, BACnet/IP, BACnet Ethernet or
L
ONTALK (FTT-10A). It is necessary to identify the data link layer that will be used when
entering an order. The communications module can also be added later in the field to an
existing controller.
Alarm Bell
Field installed and wired to the control panel to provide remote.
Electrical
Single-Point Power Block
A single power supply to a power block mounted in a box located on the unit's frame. Each
circuit is factory-wired from the box to a power block in each circuit's power panel. See
dimension drawings for the box location. Includes factory wiring to a circuit breaker located
in each circuit's power panel. Multiple-point power block (one circuit per compressor) is
standard.