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YORK INTERNATIONAL
manual dilution cycle is controlled via the MANUAL
PUMP key in the Service section of the keypad. The
PUMP STATUS key employs a scrolling feature to allow
control of the pumps, the manual dilution cycle, and the
stabilizer refrigerant solenoid valve via the MANUAL
PUMP key. In SERVICE mode, each pump may be op-
erated manually if not already required to run due to
chiller operation or the dilution cycle; in addition, if the
refrigerant temperature is below 34°F (1.1°C), the solu-
tion pump does not allow manual operation; if a respec-
tive pump’s overloads trip, the manual run signal is ter-
minated. Units equipped with Franklin pumps do not al-
low manual operation of the refrigerant, solution or gen-
erator pumps while the motor coolant float switch (2F) is
open, and units equipped with Buffalo pumps do not al-
low manual refrigerant pump operation unless both re-
frigerant level float switches (1F) and (3F) are closed.
The pump shall be on for 2 hours (except the purge pump,
which requires manual turnoff) and then automatically
turn off. While the PUMP STATUS key is used to display
the message “MANUAL DILUTION CYCLE”, the MAN-
UAL PUMP key (in SERVICE mode only) allows on/off
operation of the manual dilution cycle; with the unit off
and not in the automatic dilution cycle, it initiates a dilu-
tion cycle unless the refrigerant level float switch is open
or the refrigerant temperature is less than or equal to
34°F (1.1°C). When activated, the solution (absorber
and generator on 50 Hz Models YIA-10E3 – YIA-14F3
with Franklin pumps), refrigerant, chilled and condenser
pumps run until the refrigerant level float switch opens,
the refrigerant temperature falls to 34°F (1.1°C), or 6
minutes has elapsed. To stop the manual dilution cycle
before automatic termination, press the MANUAL PUMP
key again. The stabilizer refrigerant solenoid valve may
be controlled manually in SERVICE mode only via the
MANUAL PUMP key when the PUMP STATUS key is
used to display the “STABILIZER REFRIGERANT SO-
LENOID VALVE ON (OFF)” message and MANUAL
operation has been selected using the MANUAL PUMPS
key via the special access code in PROGRAM mode.
The on/off status for all pumps and solenoids is pro-
vided on the unit print-out. In LOCAL, REMOTE, or SER-
VICE mode, the MANUAL PUMP key is used in con-
junction with the PUMP STATUS key to control opera-
tion of the PURGE PUMP to allow manual purge opera-
tion.
To initiate a start in LOCAL mode, press the UNIT switch
on the keypad. If the steam or hot water control valve is
open less than 10% and the leaving chilled water tem-
perature is at or above setpoint, the panel displays the
message “COOLING START SEQUENCE INITIATED”
and the chilled water pump contacts close. The chilled
water and condenser flow switches are bypassed for 30
seconds each after the respective pump is turned on, or
until the respective flow switch closes, if less than 30
seconds. If the unit is kept from starting because the
leaving water temperature is below setpoint, a cycling
shutdown shall be initiated, with the background mes-
sage “WED 2:34PM LVG WATER TEMP BELOW SET-
POINT”. For LWT shutdowns only, the system starting
temperature is determined by adding 2.0°F(1.1°C) to the
leaving chilled water setpoint. Similarly, the LWT cycling
shutdown occurs when the temperature falls to 2.0°F
(1.1°C) below setpoint or a minimum of 38°F (3.3°C);
when this occurs, the dilution cycle is initiated; following
this, the chilled water pump continues to run, unless the
UNIT switch is placed in STOP/RESET position. If one
or more of the system status checks is negative, the
panel displays the “SYSTEM SHUTDOWN-PRESS STA-
TUS” message with the appropriate background mes-
sage. If all checks are normal, the chilled water pump
starts immediately. When the chilled water flow switch
closes, the condenser pump is turned on.
If the condenser water flow switch does not close within
30 seconds of the condenser pump turn-on, a cycling
shutdown is performed. When the condenser flow switch
closes, the steam/hot water shutoff valves are energized
and if the unit is equipped with Franklin pumps, the re-
frigerant pump and generator pump (50 Hz Models YIA-
10E3 - YIA-14F3) are started. Simultaneously, the panel
displays “SYSTEM RUN-LVG CHILLED WATER CON-
TROL”.
If the unit is equipped with Buffalo pumps, refrigerant
pump operation is controlled by float switches 1F and
3F. The refrigerant pump is not started until both refrig-
erant level float switches 3F and 1F close and the “RE-
FRIGERANT PUMP STARTUP DELAY” setpoint timer
has elapsed as follows: The refrigerant level will rise to a
level that causes 3F to close. As the level continues to
rise, it will cause 1F to close. When 1F closes, the RE-
FRIGERANT PUMP STARTUP DELAY setpoint timer
(1-900 seconds) is started. If 1F remains closed for the
duration of the timer, the refrigerant pump is started when
the programmed delay has elapsed. After the refriger-
ant pump has been started, if the refrigerant level de-
creases to the extent that first 1F opens and then 3F
opens, the REFRIGERANT PUMP SHUTDOWN DE-
LAY setpoint timer (1-45 seconds) is started when 3F
opens. If 3F remains open for the duration of the timer,
the refrigerant pump is shut off after the programmed
delay has elapsed. When the unit first enters SYSTEM
RUN or after a refrigerant pump shutdown has occurred
due to low refrigerant level, the REFRIGERANT FLOAT
SWITCH SHUTDOWN setpoint timer (20-60 minutes)
is started. The programmed value is the number of min-
utes the unit is allowed to run without the refrigerant pump
running. If the refrigerant pump is not started before the
timer has elapsed, a safety shutdown is initiated and
“DAY-TIME-REFRIGERANT PUMP FLOAT SW FAIL-
URE” is displayed. To assure that both 1F and 3F float
switches are operational and not stuck in one position,
the program compares the state of 1F to 3F. Since each
float switch closes as the refrigerant level rises against
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