York YCAL0014E Series, Installation Operation & Maintenance

Page: 102 / 212

JOHNSON CONTROLS
102
FORM 150.62-NM8 (1020)
UNIT CONTROLS
Program Key
There are several operating parameters under the
PROGRAM key that are programmable. These setpoints
can be changed by pressing the PROGRAM key, and
then the ENTER/ADV key to enter Program Mode.
Continuing to press the ENTER/ADV key will display
each operating parameter. While a particular parameter
is being displayed, the ↑ (UP) and ↓ (DOWN) arrow
keys can be used to change the value. After the value is
changed, the ENTER/ADV key must be pressed to enter
the data into memory. Table 21 shows the programmable
limits and default values for each operating parameter.
Following are the displays for the programmable values
in the order they appear:
d
D I S C H A R G E P R E S S U R E
C U T O U T = 3 9 5 P S I G
Discharge Pressure Cutout is the discharge pressure
at which the system will shutdown as monitored by
the optional discharge transducer. This is a software
shutdown that acts as a backup for the mechanical high
pressure switch located in the refrigerant circuit. The
system can restart when the discharge pressure drops
40 psig (2.76 barg) below the cutout point.
If the optional discharge pressure transducer is not
installed, this programmable safety would not apply.
It should be noted that every system has a mechanical
high pressure cutout that protects against excessive
high discharge pressure regardless of whether or not the
optional discharge pressure is installed.
S U C T I O N P R E S S U R E
C U T O U T = 4 4 . 0 P S I G
The SUCTION PRESSURE CUTOUT protects the chiller
from an evaporator freeze-up. If the suction pressure drops
below the cutout point, the system will shut down.
There are some exceptions when the
suction pressure is permitted to tem -
porarily drop below the cutout point.
Details are explained under the topic
of System Safeties
located in Section 2
of this IOM .
L O W A M B I E N T T E M P
C U T O U T = 2 5 . 0 ° F
The Low Ambient Temp Cutout allows the user to select
the chiller outside ambient temperature cutout point. If
the ambient falls below this point, the chiller will shut
down. Restart can occur when temperature rises 2°F
(1.11°C) above the cutout setpoint.
L E A V I N G L I Q U I D T E M P
C U T O U T = 3 6 . 0 ° F
The Leaving Liquid Temp Cutout protects the chiller
from an evaporator freeze-up. Anytime the leaving
chilled liquid temperature drops to the cutout point, the
chiller shuts down. Restart will be permitted when the
leaving chilled liquid temperature rises 2°F (1.11°C)
above the cutout setpoint.
When water cooling mode is programmed (OPTIONS
key), the value is fixed at 36.0°F (2.22°C) and cannot
be changed. Glycol cooling mode can be programmed
to values listed in Table 20.
A N T I R E C Y C L E T I M E R
= 6 0 0 S E C
The programmable anti-recycle timer assures that
systems do not cycle. This timer is programmable under
the PROGRAM key between 300 and 600 seconds.
Whenever possible, to reduce cycling and motor heating,
the anti-recycle timer should be adjusted as high as
possible. The programmable anti-recycle timer starts
the timer when the first compressor in a system starts.
The timer begins to count down. If all the compressors
in the circuit cycle off, a compressor within the circuit
will not be permitted to start until the anti-recycle timer
has timed out. If the lead system has run for less than
five minutes , 3 times in a row, the anti-recycle timer will
be extended to 10 minutes maximum.
F A N C O N T R O L O N
P R E S S U R E = X X X P S I G
The Fan Control ON Pressure is the programmed pressure
value that is used to stage the condenser fans ON, in relation
to discharge pressure. Refer to Condenser Fan Control in
Section 2 Unit Operation and Tables 27 - 31.
The microprocessor will not allow pro -
gramming the “Fan Control ON Pres -
sure” minus the Fan Control Differential
OFF Pressure below 160 psig. This as -
sures discharge pressure does not drop
too low.