Ycas 140 - 246 Fan Control Strategy - York Millennium YCAS 316 Installation Operation & Maintenance

Air cooled screw liquid chillers air cooled screw hermetic

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The standard efficiency chiller is equipped with 8 con-

denser fans; 4 per system. Fan control from discharge

pressure is standard. Fan start/stop pressures are pro-

grammable in the PROGRAM Mode (page 93) under the

FAN CONTROL DISCHARGE PRESSURE SETPOINT

and FAN ON/OFF PRESS DIFF displays. Ambient tem-

perature has no effect on fan cycling.

When discharge pressure reaches the programmed

setpoint, the first pair of fans on a respective system

starts. After the first pair of fans are brought on in the

reverse direction, discharge pressure must rise an addi-

tional 20 PSIG above the setpoint before a second pair

of fans will be brought on in the forward direction. When

this pair of fans starts, the reversing fans will turn off. If

discharge pressures rises 40 PSIG above the setpoint,

a second pair of fans will start in the forward direction.

This is the same pair of fans that originally ran in the

reverse direction. The first pair of forward fans will also

continue to run.

The point at which each pair 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

FAN

FAN RELAY

1 & 2 REV

9M & 10M

SETPOINT

(SYS 1)

5 & 6 REV

15M & 16M

SETPOINT

(SYS 2)

3 & 4 FOR

6M & 8M

SETPOINT

(SYS 1)

+ 20 PSIG

7 & 8 FOR

12M & 14M

SETPOINT

(SYS 2)

+ 20 PSIG

1 & 2 FOR

5M & 7M

SETPOINT

(SYS 1)

+ 40 PSIG

5 & 6 FOR

11M & 13M

SETPOINT

(SYS 2)

+ 40 PSIG

FIG. 40 – YCAS 140 - 246 FAN LOCATION / OPERATION

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