Product manual

62 IOMM ACR/AGR-1
Interlock wiring
The installing contractor provides all interlock wiring to field devices (such as flow switches and
pump starters). See unit wiring diagrams and field wiring diagram.
Unit set points and calibration
The control software is installed and tested by the factory before shipping. Calibration of the
controller is not necessary. All control and safety set points must be checked by the installing
contractor and adjusted as necessary before starting the unit. Controllers for McQuay chillers have
default set points. Refer to the menu items listed below.
• Control mode
• Leaving water temperature
• Head pressure settings
• Compressor staging
• Soft loading
• Holiday dates
• Internal scheduling
• Alarm functions
The default settings are suitable for most installations. The control mode is factory set for “Manual
Unit Off”. Check and set the control and safety settings for the application before starting the unit.
For more information on menu items, see the menu description section.
Modem kit
An optional modem kit allowing remote monitoring of the chiller from an off-site PC running McQuay
Monitor software is available from your local McQuay International sales representative. The modem
kit comes complete with modem, mounting bracket, wiring harness, and installation instructions. The
modem kit can be field installed or as an option at the factory. Modem wiring is shown on the field
wiring diagram.
Lead-Lag
A feature on all McQuay AGR air-cooled chillers is a system for alternating the sequence in which the
compressors start to balance the number of starts and run hours. Lead-Lag of the refrigerant circuits
is accomplished automatically through the MicroTech Controller. When in the auto mode the
compressor with the fewest number of starts will be started first. If all circuits are operating and a
stage down in the number of operating compressors is required, the circuit with the most operating
hours will cycle off first. The operator may override the MicroTech controller, and manually select the
lead circuit as circuit #1 or #2.