44
Centrifugal Chillers
D-EIMWC00804-14EN
Figure 24, Typical Oil Flow Diagram
NOTES:
1.
Diagram does not apply to CE 050 compressors, which have self-contained lubrication systems.
2.
Connections are not necessarily in correct relative location.
3.
R = relief valve, P = pressure sensor, T = temperature sensor, S = solenoid valve
Hot Gas Bypass
All units can be equipped with an optional hot gas bypass system that feeds discharge
gas directly into the evaporator when the system load falls below 10% compressor
capacity.
Light load conditions are signaled by measurement of the percentage of RLA amps by
the MicroTech II controller. When the RLA drops to the setpoint, the hot gas bypass
solenoid valve is energized, making hot gas bypass available for metering by the hot gas
regulating valve. This hot gas provides a stable refrigerant flow and keeps the chiller
from short cycling under light load conditions. It also reduces surge potential on heat
recovery units.
The factory setpoint for bringing on hot gas bypass is 40% of RLA.
Condenser Water Temperature
When the ambient wet bulb temperature is lower than design, the entering condenser
water temperature can be allowed to fall, improving chiller performance.
Daikin chillers will start with entering condenser water temperature as low as 55
°
F
(42.8
°
C) providing the chilled water temperature is below the condenser water
temperature.
The minimum operating entering condenser water temperature is a function of the
leaving chilled water temperature and load.
