D-EIMWC00804-14EN
Centrifugal Chillers
13
Figure 3, Minimum Entering Condenser Water Temperature (EXV)
Min. ECWT = 5.25 + 0.88*(LWT) - DT
FL*
(PLD/100) + 22*(PLD/100)
2
•
ECWT = Entering condenser water temperature
•
LWT = Leaving chilled water temperature
•
DT
FL
= Chilled Water Delta-T at full load
•
PLD = The percent chiller load point to be checked
For example; at 44
°
F LWT, 10 degree F Delta-T, and 50% full load operation, the
entering condenser water temperature could be as low as 44.5
°
F. This provides excellent
operation with water-side economizer systems.
Over 300 Tons
Chillers over 300 tons are equipped with thermal expansion valves (TXV) and will start
and run with entering condenser water temperatures as low as calculated by the
following equation and shown in the chart following.
Min. ECWT = 7.25 + LWT– 1.25* DT
FL
(PLD/100) + 22*(PLD/100)
2
•
ECWT = Entering condenser water temperature
•
LWT = Leaving chilled water temperature
•
DT
FL
= Chilled Water Delta-T at full load
•
PLD = The percent chiller load point to be checked
Figure 4, Minimum Entering Condenser Water Temperature (TXV)
Minimum Entering Condenser Water Temperature - 10 F Range
30.0
35.0
40.0
45.0
50.0
55.0
60.0
65.0
0
10
20
30
40
50
60
70
80
90
100
110
Percent Load
E
C
W
T
,
F
44 LChWT
42 LChWT
46 LChWT
