Unit Piping
20 CG-SVX038A-EN
treatment of the chilled water loop is required and must be
performed by a qualified water specialist.
Wye Strainer — Required
A wye strainer with 20 mesh screen must be installed
immediately adjacent to the inlet water connection to the
evaporator.
Important: Operation of the chiller without this wye
strainer AND 20 mesh screen in place will
void the unit warranty.
Flow Proving Device — Required
Optional chilled water flow switch or other factory
approved flow proving device is mandatory. It is field-
installed by others. Flow switch is to be installed and
maintained in accordance with manufacturer’s
recommendations and interconnected to the unit control
panel as described in the field-wiring diagram. To provide
additional chiller protection, wire the flow proving device
control circuit in series with a chilled water pump starter
normally open auxiliary contact to create a chilled water
pump interlock. See “Chilled Water Flow Switch,” p. 28.
Chilled Water System Volume
Trane requires minimum system volumes as indicated in
Tab le 7 . Special applications may allow deviation from
these volumes, but only with approval of Trane
engineering. Operation below these volumes will cause
unacceptable system control problems and the potential
for evaporator failure.
Condenser Water Piping
Condenser water piping and associated components shall
be installed in accordance with condenser water piping
schematic Figure 4, p. 22. Condenser water inlet and outlet
types, sizes and locations are provided in Table 4, p. 12 and
Table 5, p. 14.
Discharge Pressure Control/
Optional Factory-Installed Water
Regulating Valve
A means of maintaining stable discharge pressure during
full-load, part-load and transient conditions is required.
Saturated discharge temperature must be maintained
between 80°F and 128°F. Trane offers an optional factory
installed water regulating valve that is controlled by the
unit controller. The optional water regulating valve
maintains condensing pressure and temperature by
throttling water flow leaving the condenser in response to
compressor discharge pressure. Field-supplied water
regulating valves must be adjusted for proper operation
during full-load, part-load and transient conditions. Field-
supplied water regulating valves must also be ad ju st ed fo r
proper positioning when unit is off.
Alternative field-supplied methods for condensing
pressure/temperature control include the use of cooling
tower control strategies. Cooling tower systems may
include a manual or automatic bypass valve that can alter
water flow rate and basin temperature to maintain stable
condensing temperature at the chiller.
Well or city water condensing systems should include a
water regulating valve and potentially a pressure reducing
valve. A pressure reducing valve should be installed to
reduce water pressure entering the condenser if water
pressure can exceed tube-side maximum allowable
working pressure as indicated on the condenser
nameplate. This is also necessary to prevent damage to
NOTICE:
Proper Water Treatment!
The use of untreated or improperly treated water could
result in scaling, erosion, corrosion, algae or slime. It is
recommended that the services of a qualified water
treatment specialist be engaged to determine what
water treatment, if any, is required. Trane assumes no
responsibility for equipment failures which result from
untreated or improperly treated water, or saline or
brackish water.
NOTICE:
Unexpected Chiller Start!
Failure to follow instructions could cause the chiller to
start unexpectedly which could result in equipment or
property damage. An external source (EMS, time clock
or any other means) should not be allowed to bring on
a pump that would trigger the flow switch to start the
chiller. The flow switch is meant to act as a safety
switch and not a start/stop mechanism.
Table 7. Minimum system volumes
CGWR/CCAR Unit Size
(tons)
Minimum System Volume
(gal)
20 157
30 226
40 311
50 355
65 442
NOTICE:
Excessive Water Pressure!
To prevent condenser or regulating valve damage, do
not exceed nameplate condenser water pressure.
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