York 160.87-OM1, Operation And Maintenance Manual

Page: 142 / 268

Table 138: Programmable
Button Access level Description
Local Leaving
Chilled Liquid
Temperature
– Setpoint
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 72.0°F (water) or
10.0°F to 72.0°F (brine). If Smart Freeze is enabled, the range is
36.0°F to 70.0°F (water). A remote device can provide an analog
signal (0 to 20 mA, 4 to 20mA, 0 to 10VDC or 2 to 10VDC) 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 from to 10.0°F to 40.0°F above the BASE Setpoint (refer
to the Remote Leaving Chilled Liquid Temperature Setpoint Range
description). Additionally, E-Link or SC-EQ communications (in ISN
Remote mode) can define the setpoint through a serial data stream.
In this case, the incoming setpoint is not an offset that is applied
to the locally programmed BASE Setpoint value, but rather is the
setpoint value itself.
Leaving
Chilled Liquid
Temperature
Cycling
Offset –
Shutdown
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 minimum cut­out of 36°F (water), 34°F
(water with Smart Freeze enabled) or 6°F (brine). It establishes
the minimum allowed temperature for the Leaving Chilled Liquid
Temperature and prevents over-cooling of the building. Anytime
the Leaving Chilled Liquid Temperature Setpoint is increased, the
shutdown threshold is 36.0°F (water) or 6.0°F (brine) for the next
ten (10) minutes. If Smart Freeze is enabled, the threshold is 34.0°F
for the next 10 minutes. After ten (10) minutes have elapsed, the
shutdown threshold becomes the programmed setpoint value.
Leaving
Chilled Liquid
Temperature
Cycling
Offset –
Restart
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 shutdown.
This is done by defining an offset above the Leaving Chilled Liquid
Temperature Setpoint. It is programmable over a range of 0°F to
(80 - Local Leaving Chilled Liquid Temp Setpoint). This allows 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.
Remote
Analog Input
Range
Operator
This setpoint defines, for the Control Center, the remote signal
range applied for remote reset of the Leaving Chilled Liquid
Temperature Setpoint and Current Limit Setpoint in Analog Remote
mode. If the remote signal is 0 to 10VDC or 0 to 20mA, this setpoint
must be programmed for 0 to 10VDC. If the remote signal is 2 to
10VDC or 4 to 20mA, this setpoint must be programmed for 2 to
10VDC.
YK-EP Style B Centrifugal Chiller 142