Specifications

Catalog WSC/WDC-4 51
Low Condenser Water Temperature Operation
When ambient wet bulb temperature are lower than design, the condenser water temperature can
be allowed to fall. Lower temperatures will improve chiller performance.
Up to 300 Tons
McQuay centrifugal chillers up to 300 tons are equipped with electronic expansion valves (EXV)
and will start and run with entering condenser water temperatures as low as shown in Figure 13 or
as calculated from the following equation on which the curves are based.
Figure 13, 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
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 102030405060708090100110
Percent Load
ECWT, F
44 LChWT
42 LChWT
46 LChWT