Daikin WCT Series Operating & Maintenance Manual page 79

EVAPORATOR :
SYMPTOM
High Evaporator Approach Temperature with
High Discharge Temperature
High Evaporator Approach Temperature with
Normal Discharge Temp
Low Evaporator water leaving
Temperature with w/ Low Motor
Extreme Low
Current
Suction Pressure
Low Evaporator water leaving
High Evaporator Temperature
pressure
Overall reduced performance due
Low discharge to refrigerant accumulation in
superheat Evaporator
CONDENSER
SYMPTOM
Condenser Approach temperature is
higher than normal
High Condenser water range with
normal Evaporator temperature
Extreme High
Discharge Pressure
Overall performance loss
OMM WCT
RESULTS Possible Cause
Low Charge
EXV problem
Dirty or restricted
evaporator tubes
Insufficient Load for system
capacity
IGV failed to open
System Overload
Economizer float
valves are stuck
open
RESULTS Possible Cause
Air in Condenser
Insufficient
Condenser water
flow rate
Condenser Tubes
are dirty/scaled
High Condenser
water entering
temperature
Centrifugal Chillers
Remedy
Check for leaks and add charge
Remove obstruction
Clean Evaporator Tubes and/or
Check water conditioning
Check IGV motor operation and set point
of Evaporator water leaving temperature
cutout
Check Cutout setting and increase it if
necessary so Evaporator water leaving
temperature will not be so low and the unit will shut
down NOT causing low suction
pressure anymore
IGV might not be Full Open but not give enough load
due to linkage slippage etc.
Check the IGV motor positioning circuit
Be sure the vanes are wide open without
overloading the motor until the load
decreases
Adjust EXV until system stabilizes
Remedy
Take refrigerant charge out and put the unit
on a vacuum pump and then recharge
Increase Condenser water flow rate
Clean Condenser tubes and/or check water
conditioning
Reduce Condenser water entering
Temperature (check cooling tower and
water circulation)
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