Unit Controls
20sec. unloading
30sec. unloading
60sec. unloading
control range
(no compressor staging)
60sec. loading
LWT | 42.5°F | 43.5°F | 44.0°F | 46.0°F | 48.0° | |
(5.8°C) | (6.4°C) | (6.7°C) | (7.8°C) | (8.9°C) | ||
| ||||||
|
|
| Low Limit | Setpoint | High limit |
Leaving Water Temp. Control – Compressor Staging
Setpoint = 46.0°F (7.8°C) Range = +/- 2°F(1.1°C)
FIG. 6 – LEAVING WATER TEMPERATURE CONTROL
TABLE 32 – LEAVING CHILLED LIQUID CONTROL FOR 6 COMPRESSORS (8 STEPS)
| LEAD SYSTEM |
|
|
| LAG SYSTEM |
| |||
|
|
|
|
|
|
|
|
|
|
*STEP | COMP 1 | COMP 2 | COMP 3 |
| COMP 1 |
| COMP 2 |
| COMP 3 |
0 | OFF | OFF | OFF |
| OFF |
| OFF |
| OFF |
1 | ON+HG | OFF | OFF | SEE NOTE 1 | OFF |
| OFF |
| OFF |
2 | ON | OFF | OFF |
| OFF |
| OFF |
| OFF |
3 | ON | OFF | OFF | SEE NOTE 2 | ON |
| OFF |
| OFF |
4 | ON | ON | OFF | SEE NOTE 3 | OFF |
| OFF |
| OFF |
5 | ON | ON | OFF |
| ON |
| OFF |
| OFF |
6 | ON | ON | OFF |
| ON |
| ON |
| OFF |
7 | ON | ON | ON |
| ON |
| ON |
| OFF |
8 | ON | ON | ON |
| ON |
| ON |
| ON |
|
|
|
|
|
|
|
|
|
|
TABLE 33 – LEAVING CHILLED LIQUID CONTROL FOR 4 COMPRESSORS (6 STEPS)
| LEAD SYSTEM |
|
|
| LAG SYSTEM | |
*STEP | COMP 1 | COMP 2 |
| COMP 1 |
| COMP 2 |
0 | OFF | OFF |
| OFF |
| OFF |
1 | ON+HG | OFF | SEE NOTE 1 | OFF |
| OFF |
2 | ON | OFF |
| OFF |
| OFF |
3 | ON | OFF | SEE NOTE 2 | ON |
| OFF |
4 | ON | ON | SEE NOTE 3 | OFF |
| OFF |
5 | ON | ON |
| ON |
| OFF |
6 | ON | ON |
| ON |
| ON |
* STEP can be viewed using the OPER DATA key and scrolling to COOLING DEMAND.
86 | YORK INTERNATIONAL |
