York MILLENNIUM YCAL0043SC, Manual

Page: 83 / 133

YORK INTERNATIONAL
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FORM 150.62-NM2
Compressor Staging for Return Water Control – 6 Compressors
Cooling Setpoint = 45° F (7.2° C) Range = 10° F (5.6° C)
Notes:
1. Step 1 is Hot Gas Bypass and is skipped when loading occurs. Hot Gas Bypass operation is inhibited during Pumpdown.
2. Step 3 is skipped when loading occurs.
3. Step 4 is skipped when unloading occurs.
TABLE 35 – RETURN CHILLED LIQUID CONTROL FOR 4 COMPRESSORS (6 STEPS)
*STEP COMPRESSOR ON POINT COMPRESSOR OFF POINT
0
1
SETPOINT
2 SP + CR/4 SP + CR/8 SEE NOTE 1
3 SP + 2*CR/4 SP + CR/4 SEE NOTE 2
4 SP + 2*CR/4 SP + CR/4 SEE NOTE 3
5 SP + 3*CR/4 SP + 2*CR/4
6 SP + CR SP + 3*CR/4
TABLE 34 – RETURN CHILLED LIQUID CONTROL FOR 6 COMPRESSORS (8 STEPS)
*STEP COMPRESSOR ON POINT COMPRESSOR OFF POINT
0
1
SETPOINT
2 SP + CR/6 SP + CR/8 SEE NOTE 1
3 SP + 2*CR/6 SP + CR/6 SEE NOTE 2
4 SP + 2*CR/6 SP + CR/6 SEE NOTE 3
5 SP + 3*CR/6 SP + 2*CR/6
6 SP + 4*CR/6 SP + 3*CR/6
7 SP + 5*CR/6 SP + 4*CR/6
8 SP + CR SP + 5*CR/6
TABLE 33 – COMPRESSOR STAGING FOR RETURN WATER CONTROL
*Unloading only
# OF COMP ON 0 *1+HG 1 2 3 4 5 6
RWT
45°F 46.25°F 46.7°F 48.3°F 50.0°F 51.7°F 53.4°F 55.0°F
(7.2°C) (7.9°C) (8.2°C) (9.1°C) (10.0°C) (11.0°C) (11.9°C) (12.8°C)
* STEP can be viewed using the OPER DATA key and scrolling to COOLING DEMAND.
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