IOMM AGZB1 AGZ 010B through 034B 41
Pumpdown Pressure
The pressure to which a circuit will pumpdown is based on the Low Evaporator Pressure
Unload setpoint. The equation is as follows:
Pumpdown pressure = Low evap pressure unload – 15 psi , with the calculated value
limited to a minimum of 10 psi.
Unit Enable
Enabling and disabling the chiller is controlled by the Unit Enable Setpoint with options of
OFF and ON. This setpoint can be altered by the Unit OFF input, Remote input, keypad
entry, and BAS request. The Control Source Setpoint determines which sources can change
the Unit Enable Setpoint with options of SWITCHES, KEYPAD or NETWORK.
Changing the Unit Enable Setpoint can be accomplished according to the following table.
NOTE: An “x” indicates that the value is ignored.
Unit Off
Input
Control Source
Setpoint
Remote
Input
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
Unit Mode
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. This setpoint can be altered by the
keypad, BAS, and Mode input. Changes to the Unit Mode Setpoint are controlled by two
additional setpoints.
• Available Modes Setpoint: Determines the operational modes available at any time
with options of COOL, COOL w/Glycol, COOL/ICE w/Glycol, ICE w/Glycol and
TEST.
• Control Source Setpoint: Determines the source that can change the Unit Mode
Setpoint with options of KEYPAD, NETWORK, or SWITCHES.
When the Control source is set to KEYPAD, the Unit Mode stays at its previous setting
until changed by the operator. When the Control source is set to BAS, the most recent BAS
mode request goes into effect even if it changed while the Control source was set to
KEYPAD or DIGITAL INPUTS.
Changing the Unit Mode Setpoint can be accomplished according to the following table.
NOTE: An “x” indicates that the value is ignored.
Control Source
Setpoint
Mode
Input
Keypad Entry
BAS
Request
Available Modes
Setpoint
Unit Mode
x x x x
COOL
COOL
x x x x COOL w/Glycol COOL w/Glycol
SWITCHES OFF x x COOL/ICE w/Glycol COOL w/Glycol
SWITCHES ON x x COOL/ICE w/Glycol ICE w/Glycol
KEYPAD x COOL w/Glycol x COOL/ICE w/Glycol COOL w/Glycol
KEYPAD x ICE w/Glycol x COOL/ICE w/Glycol ICE w/Glycol
NETWORK x x COOL COOL/ICE w/Glycol COOL w/Glycol
NETWORK x x ICE COOL/ICE w/Glycol ICE w/Glycol
x x x x ICE w/Glycol ICE w/Glycol
x x x x TEST TEST
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