York YCAL0014E Series, Installation Operation & Maintenance

Page: 100 / 212

JOHNSON CONTROLS
100
FORM 150.62-NM8 (1020)
UNIT CONTROLS
Notice that the RANGE was programmed for plus or
minus X.X°F. This indicates the setpoint to be in the
center of the control range. If the control mode has been
programmed for Return Liquid Control, the message
below would be displayed in place of the previous
message.
When in leaving chilled liquid temperature control, the
microprocessor will attempt to control the leaving water
temperature within the temperature range of the setpoint
plus or minus the range. In the above example, control
will be in the range of 43 to 47°F.
Return Chilled Liquid Control
S E T P O I N T = 4 5 . 0 ° F
R A N G E = + 2 . 0 ° F
Notice that the range no longer has a plus or minus
X.X°F, but only a + X.X°F RANGE setpoint. This
indicates that the setpoint is not centered within the range
but could be described as the bottom of the control range.
A listing of the limits and the programmable values for
the COOLING SETPOINTS are shown in Table 20.
The SETPOINT and RANGE displays just described
were based on local control. If the unit was programmed
for remote control (under the OPTIONS key), the above
programmed setpoints would have no effect.
When in return chilled liquid temperature control, the
microprocessor will turn all compressors OFF at setpoint
and will turn compressors ON as return chilled liquid
temperature rises. All compressors will be on at setpoint
plus the range. If the range equals the temperature drop
across the evaporator when fully loaded, the leaving
chilled liquid temperature will remain near the setpoint
plus or minus a few degrees as the chiller loads and
unloads according to return chilled liquid temperature.
Both Leaving and Return control are described in detail
under the section on “Capacity Control”. See Unit
Operation in Section 2 of this IOM
Pressing the COOLING SETPOINTS key a second
time will display the remote setpoint and cooling
range. This display automatically updates about every
2 seconds. Notice that these setpoints are not “locally”
programmable, but are controlled by a remote device
such as an ISN control. These setpoints would only be
valid if the unit was operating in the Remote mode.
The messages below illustrate both Leaving Chilled
Liquid Control and Return Chilled Liquid Control
respectively.
R E M S E T P = 4 4 . 0 ° F
R A N G E = + / - 2 . 0 ° F
(leaving chilled liquid control)
R E M S E T P = 4 4 . 0 ° F
R A N G E = + 1 0 . 0 ° F
(return chilled liquid control)
The low limit, high limit, and default values for the keys
under “SETPOINTS” are listed in Table 20.
Pressing the COOLING SETPOINTS a third time will
bring up the display that allows the Maximum EMS-
PWM Temperature Reset to be programmed. This
message is shown below.
M A X E M S - P W M R E M O T E
T E M P R E S E T = + 2 0 ° F
The Temp Reset value is the maximum allowable reset
of the temperature setpoint. The setpoint can be reset
upwards by the use of a contact closure on the PWM
Temp Reset input (CTB1 terminals 13 and 20).
See the
section on Operating Controls for a detailed explanation
of this feature.
As with the other setpoints, the UP arrow and DOWN
arrow keys are used to change the Temp Reset value.
After using the ↑ (UP) and ↓ (DOWN) arrows to adjust
to the desired setpoint, the ENTER/ADV key must be
pressed to enter this number into memory.
Schedule/Advance Day Key
The schedule is a seven day daily schedule that allows
one start/stop time per day. The schedule can be
programmed Monday through Sunday with an alternate
holiday schedule available. If no start/stop times are
programmed, the unit will run on demand, providing the
chiller is not shut OFF on a unit or system shutdown. The
daily schedule is considered “not programmed” when
the times in the schedule are all zeros (00:00 AM).
To set the schedule, press the SCHEDULE/ADVANCE
DAY key. The display will immediately show the
following display.
M O N S T A R T = 0 0 : 0 0 A M
S T O P = 0 0 : 0 0 A M