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JOHNSON CONTROLS
36
FORM 160.79-O3
ISSUE DATE: 11/09/2018
SECTION 2 – OPTIVIEW CONTROL CENTER
Restart
Displays the Leaving Chilled Liquid Temperature at
which the chiller will restart after it has shut down due to
over-cooling temperature. By default, the chiller will re-
start at the Leaving Chilled Liquid Temperature Setpoint,
but is adjustable.
PROGRAMMABLE
Local Leaving Chilled Liquid Temperature -
Setpoint
Access Level Required: OPERATOR
This value allows the user to define the Leaving
Chilled Liquid Temperature that is to be maintained by
the chiller. It is programmable over the range of 38.0°F
to 70.0°F (water) or 10.0°F to 70.0°F (brine). If Smart
Freeze (see below) is enabled, the range is 36.0°F to
70.0°F (water). A remote device can provide an analog
signal (0-20 mA, 4-20 mA, 0-10 VDC or 2-10 VDC)
in Analog Remote mode, or PWM signal in Digital
Remote mode that changes the setpoint by creating an
offset above the operator programmed Base Leaving
Chilled Liquid Temperature setpoint. This offset may
be defined between 10.0°F and 40.0°F above the Base
setpoint (see the Remote Leaving Chilled Liquid Tem-
perature Setpoint Range description below). Addition-
ally, an SC-EQ (in ISN BAS Remote mode) can de-
fine the setpoint through communications. In this case,
the incoming setpoint is not an offset, but rather is the
setpoint value itself.
Local Leaving Chilled Liquid Temperature -
Remote Range
Access Level Required: OPERATOR
This is the range over which an analog (0-20 mA, 4-20
mA, 0-10 VDC or 2-10 VDC) in Analog Remote Mode
or a digital signal (PWM) in Digital remote mode can
reset the Leaving Chilled Liquid Temperature setpoint
above the operator programmed Base Setpoint (see be-
low). Programmable between 10°F and 40°F, with a
default of 10°F, it is added to the Base value to create
a range over which the remote device can reset the set-
point. For example, if this setpoint is programmed for
10°F and the operator programmed value is 45°F, then
the remote device can set the Leaving Chilled Liquid
Temperature setpoint over the range 45.0°F to 55.0°F.
Leaving Chilled Liquid Temperature Cycling
Effective Offset - Shutdown
Access Level Required: OPERATOR
This value allows the user to specify the Leaving
Chilled Liquid Temperature at which the chiller will
shut down on a
LEAVING CHILLED LIQUID –
LOW TEMPERATURE
cycling shutdown. This is
done by defining an offset below the Leaving Chilled
Liquid Temperature setpoint. It is programmable over
a range of 1°F to 70°F below the setpoint, to a mini-
mum cutout of 36°F (water), 34°F (water with Smart
Freeze enabled) or 6°F (brine). It establishes the mini-
mum allowable temperature for the Leaving Chilled
Liquid Temperature and prevents over-cooling of the
building. Anytime the Leaving Chilled Liquid Tem-
perature setpoint is increased, the shutdown threshold
is 36.0°F (water) or 6.0°F (brine) and then ramped up
to the desired setpoint at the rate of 0.1°F/second. If
Smart Freeze (see below) is enabled, the initial thresh-
old is 34.0°F.
Leaving Chilled Liquid Temperature Cycling
Offset - Restart
Access Level Required: OPERATOR
This value allows the user to specify the Leaving
Chilled Liquid Temperature at which the chiller will
restart after a shutdown on a
LEAVING CHILLED
LIQUID – LOW TEMPERATURE
cycling shut-
down. This is done by defining an offset above the
Leaving Chilled Liquid Temperature setpoint. It is
programmable over a range of 0°F to 35°F above the
setpoint, to a maximum restart value of 80°F. The
chiller will automatically restart when this temperature
is reached. This setpoint can be used to reduce chiller
cycling by delaying the chiller restart until the cooling
load has increased.
Brine Low Evaporator Cutout
Access Level Required: SERVICE
This value is only available in Brine mode. It allows
the user to specify the Evaporator Pressure at which a
safety shutdown is initiated.
Smart Freeze (Off / On)
Access Level Required: SERVICE
This value is only available if the chiller is not in Brine
mode. It allows the user to enable the Smart Freeze
Point Operation which allows the chiller to run closer
to the freeze point without shutting down.