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The high efficiency chiller is equipped with 12 condenser
fans; 6 per system. Fan control from discharge pressure
is standard. Fan start/stop pressures are programmable
in the PROGRAM Mode (page 93) under the FAN CON-
TROL DISCHARGE PRESSURE SETPOINT and FAN
ON/OFF PRESS DIFF displays. Ambient temperature
has no effect on fan cycling.
When discharge pressure reaches the programmed
setpoint, the first trio of fans on a respective system
starts. After the first trio of fans are brought on in the
reverse direction, discharge pressure must rise an addi-
tional 20 PSIG above the setpoint before a second trio of
fans will be brought on in the forward direction. When this
trio of fans starts, the reversing fans will turn off. If dis-
charge pressures rises 40 PSIG above the setpoint, a
second trio of fans will start in the forward direction. This
is the same trio of fans that originally ran in the reverse
direction. The first trio of forward fans will also continue
to run.
The point at which each trio of fans cycles off is also
programmable. This is accomplished in the PROGRAM
Mode when the FAN ON/OFF PRESS DIFF display ap-
pears. The programmable "differential" establishes the
pressure at which each trio of fans turn off. The "differen-
tial" is the amount the discharge pressure must drop be-
low the pressure at which the fan turned on.
Locations of the fans and a table showing the operation
is shown in Fig. 41.
FAN
FAN RELAY
1, 2 & 9 REV
9M, 10M & 21 M
(SYS 1)
OR
5, 6 & 10 REV 15M, 16M & 22M
(SYS 2)
3, 4 & 11 FOR
6M, 8M & 19M
(SYS 1)
OR
7, 8 & 12 FOR 12M, 14M & 20M
(SYS 2)
1, 2 & 9 FOR
5M, 7M & 17M
(SYS 1)
OR
5, 6 & 10 FOR 11M, 13M & 18M
(SYS 2)
FIG. 41 – YCAS 216X - 266X FAN LOCATION / OPERATION
132
YCAS 216X - 266X FAN CONTROL STRATEGY
PRESSURE
ON
OFF
SETPOINT
SETPOINT – DIFF.
SETPOINT
SETPOINT – DIFF.
SETPOINT (SETPOINT + 20 PSIG)
+ 20 PSIG
– DIFF
SETPOINT (SETPOINT + 20 PSIG)
+ 20 PSIG
– DIFF
SETPOINT (SETPOINT + 40 PSIG)
+ 40 PSIG
– DIFF
SETPOINT (SETPOINT + 40 PSIG)
+ 40 PSIG
– DIFF
LD01268
YORK INTERNATIONAL
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