Water To Evaporator Connection; Minimum Water Volume - Trane CGCL 200 Installation Operation & Maintenance

Table 6 - Recommended water loop volume at Eurovent conditions
Unit size
Cooling Capacity full load (kW)
Chiller data
Biggest step (%)
Biggest step (kW)
Minimum water loop for comfort application (l)
This table is estimated with : 35°C ambient air temperature, 12/7°C water temperature, water (no glycol), deadband of 3°C.
CGCL-SVX01B-E4
Installation
Water to evaporator
connection
Before making any connections,
make sure the labelling for entering
and leaving water corresponds to
the submittals.
Install water circulation pump
upstream of the evaporator, insuring
that the evaporator is under positive
pressure.
Tables for water connections
diameter are shown on the certified
submittals.
These drawings are available on
request from your Trane Sales Office.
Figure 7
10
1. Pressure gauges: show entering and leaving water
pressure (2 pressure ports are available inside of the
unit - see item 1 in Figure 7)
2. Balancing valve: adjusts water flow.
3. Air purge allows to remove the air from the water
circuit during fill up.
4. Stop valves: isolate chillers and water circuiting
pump during maintenance operations.
5. Thermometers: indicate chilled water entering and
leaving temperatures (not mandatory).
6. Expansion compensators: avoid mechanical stress
between chiller and piping installation.
7. Stop valve located on the outlet connection: used to
measure the water pressure inlet or outlet of
evaporator.
8. Strainer: avoid getting heat exchangers dirty. All
installation must be equipped with efficient strainer
in order that only clean water enters into exchanger.
If there is no strainer, reserve will be formulated by
the Trane technician at the start-up of the unit.
The strainer used must be able to stop all particles
with a diameter greater than 1.6 mm.
9. Draining and charging: used to drain and charge the
plate heat exchanger.
10.Charging valve
200
49.2
50
24.6
235

Minimum water volume

Why the water volume is an
important parameter?
The water volume is an important
parameter because it allows a stable
chilled water temperature and avoids
short cycle operation of the
compressors.
Parameters which influence the
water temperature stability
• Water loop volume.
• Load fluctuation.
• Number of capacity steps.
• Compressors rotation.
• Dead band (adjusted by control
CH530).
• Minimum time between 2 starts
of a compressor.
Minimum water volume for a
comfort application
For comfort application we can allow
water temperature fluctuation at part
load. The parameter to take into
account is the minimum operating
time of the compressor.
In order to avoid lubrication problem
on a scroll compressor it must run at
least 2 minutes (120 seconds) before
it stops.
The minimum volume can be
determined by using the following
formula:
Volume = Cooling capacity x Time x
highest capacity step (%) / Specific
heat / Dead band
Minimum operating time =
120 seconds
Specific heat = 4.18 kJ / kg
Average Dead band = 3°C (or 2°C)
Note: To estimate the biggest step, it
is usually more reliable to make a
selection at lower ambient
temperature where efficiency is
higher and compressors steps
bigger. It is also essential to take
into account the brine specific heat,
in case of the use of glycol.
250 300 350 400
61.1 74.0 86.9 101.0
60 50 43 38
36.7 37.0 37.2 37.9
351 354 356 363
450 500 600
111.0 126.0 152.0
33 30 25
36.6 37.8 38.0
350 362 364
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