Catalogue

8 CG-PRC017H-EN
Application Considerations
Water Temperature
Leaving Water Temperature Limits
Trane CGAM chillers have three distinct leaving water categories:
• standard, with a leaving solution range of 42 to 65°F (5.5 to 18°C)
• low temperature process cooling, with leaving solution range of 10 to 65°F (-12 to 18°C)
• ice-making, with leaving solution range of 20 to 65°F (-7 to 18°C)
Since leaving solution temperature below 42°F (5.5°C) results in suction temperature at or below
the freezing point of water, a glycol solution is required for all low temperature and ice-making
machines. Ice making control includes dual setpoint controls and safeties for ice making and
standard cooling capabilities. Consult your localTrane account manager for applications or
selections involving low temperature or ice making machines.
The maximum water temperature that can be circulated through the CGAM evaporator when the
unit is not operating is 125°F (51.7°C). Evaporator damage may result above this temperature.
Leaving Water Temperature Out of Range
Similar to the flow rate limitations above, many process cooling jobs require temperature ranges
that are outside the allowable minimum and maximum operating values for the chiller. Figure 2
below shows a simple example of a mixed water piping arrangement change that can permit
reliable chiller operation while meeting such cooling conditions. For example, a laboratory load
requires 238 gpm (5 l/s) of water entering the process at 86°F (30°C) and returning at 95°F (35°C).
The chiller’s maximum leaving chilled water temperature of 65°F (15.6°C) prevents direct supply to
the load. In the example shown, both the chiller and process flow rates are equal, however, this is
not necessary. For example, if the chiller had a higher flow rate, there would simply be more water
bypassing and mixing with warm water returning to the chiller.
Supply WaterTemperature Drop
The cataloged performance data for theTrane CGAM chiller is based on a chilled water temperature
drop of 10°F (6°C) for I-P data and 9°F (5°C) for SI data. Full load chilled water temperature drops
from 6 to 18°F (3.3 to 10°C) may be used as long as minimum and maximum water temperature
and minimum and maximum flow rates are not violated.Temperature drops outside this range at
full load conditions are beyond the optimum range for control and may adversely affect the
Figure 2. Temperature out of range system solution
L
P
P
59°F (15°C)
86°F (30°C)
238 gpm
(15 l/s)
95°F
(35°C)
178 gpm
(11.2 l/s)
95°F (35°C)
238 gpm (15 l/s)
95°F (35°C)
60 gpm (3.8 l/s)
59°F
(15°C)
178 gpm
(11.2 l/s)
68°F (20°C)
238 gpm (15 l/s)
60 gpm (3.8 l/s)
238 gpm (15 l/s)
59°F (15°C)