OM AGSB-5
27
1. The Mode field is an informational display, showing the active control mode of the
chiller. It is used as an input only when the source is set to keypad, only then can this
field be changed manually.
2. The Source field has three options, “SWITCHES” (default), “KEYPAD”, and “BAS
NETWORK”.
a.
Switches source is used when there is no BAS interface
used. This allows the unit switches to function as pumpdown and shut down
switches for the circuit. This option is used with applications using the remote
start/stop input and not using a BAS interface.
b.
Keypad source is used to override BAS or remote start/stop
commands. This would be used for servicing only.
c.
BAS Network source would be used for those applications
using “MODBUS”, “BACNET”, or “LON” communications through a building
automation system. BAS Protocol is set at Set Unit Setpoints item #11.
Table 19, Unit Enable Settings
Unit On/Off
Switch
Control Source
Setpoint
Remote
Stop Switch
Key-pad
Entry
BAS
Request
Unit
Enable
OFF x x
x
x
OFF
x SWITCHES
OFF
x
x
OFF
ON SWITCHES
ON
x x
ON
ON KEYPAD x
OFF
x
OFF
ON KEYPAD x
ON
x
ON
ON NETWORK x x
OFF
OFF
ON NETWORK
OFF
x x
OFF
ON NETWORK
ON
x
ON
ON
All methods of disabling the chiller, except for the unit switch, will cause a normal
shutdown of any running circuits. Any time the unit switch is used to disable the chiller, all
running circuits will shut down immediately, without pumping down.
Shutdown by the unit switch without going through the pumpdown cycle is undesirable and
should only be used for an emergency shutdown or for disabling the unit after both circuits
have gone through a normal shutdown.
Unit Mode Selection
The overall operating mode of the chiller is set by the Unit Mode Setpoint with options of
COOL, COOL w/Glycol, ICE w/Glycol, and TEST. The system switch must be off (unit
not running) to change the mode of operation.
Available Modes setpoint: usually set during initial setup and determines the operational
modes available at any time with options of:
•
COOL, cooling only operation, with setpoints available for normal water temperatures.
•
COOL w/Glycol, cooling only operation, allows lower setpoints than COOL.
•
COOL/ICE w/Glycol, allows cooling and ice mode operation, switchable by a remote
digital signal, by the network or through the keypad.
•
ICE w/Glycol, ice mode only, i.e., full load operation until LWT setpoint is reached.
•
TEST
Summary of Contents for AGS 206A
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