these parameters. Condenser level is detected by the liquid level sensor and controlled to the
programmed setpoint by the chiller control logic.
Equations
• Evaporator Approach = (LELT) - (SET)
• Discharge Superheat = (CDGT) - (SCT)
Definitions
• SET = Saturated Evaporator Temperature
• LELT = Leaving Evaporator Liquid Temperature
• CDGT = Compressor Discharge Gas Temperature
• SCT = Saturated Condensing Temperature
The parameters can be viewed on the control center. The chiller must be at design operating
conditions and full load operation before the correct refrigerant charge level can be properly
determined when operating. When the correct condenser level is set, evaporator approach can be
trended at constant operating points to monitor potential loss of charge.
Liquid refrigerant will be visible in the evaporator sight glass, but the refrigerant charge amount
cannot be correctly determined by viewing the liquid refrigerant level in the evaporator sight glass.
The level changes due to suction conditions and load. If exact conditions are repeated, level should
repeat in the glass from a known baseline.
Handling refrigerant for dismantling and repairs
If it becomes necessary to open any part of the refrigerant system for repairs, it will be necessary
to remove the charge before opening any part of the unit. If the chiller is equipped with optional
valves, the refrigerant can be isolated in either the condenser or evaporator / compressor while
making any necessary repairs.
Compressor and motor
1. Check mounting screws and piping joint nuts frequently to insure tightness.
2. Test motor windings annually to check for deterioration of windings.
Electrical test of motor winding resistance should be performed by a qualified service
technician according to Service Instructions Manual (Form 160.84-M1) because it involves
determination of power leads between the motor and the VSD. Results from these winding
insulation resistance tests should be trended each interval to determine degradation in
motor windings.
Table 95: Approximate refrigerant and water weight
Evaporator Condenser
Refrigerant weight lbs (kg)
1
Water weight lbs
2
CB2110 540 (250) 980 (450)
EB2510
CB2510 600 (270) 1310 (600)
EB2514 CB2514 840 (380) 1680 (770)
CB2510 640 (290) 1510 (690)
EB2910
CB2910 860 (390) 1760 (800)
CB2514 900 (410) 1940 (880)
EB2914
CB2914 1210 (550) 2240 (1020)
CB2910 920 (420) 2070 (940)
EB3310
CB3310 980 (450) 2580 (1170)
YMC
2
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