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Installation Mechanical
Typically, a three-minute water loop circulation time is
sufficient to prevent short water loop issues. Therefore, as
a guideline, ensure the volume of water in the chilled water
loop is greater than or equal to three times the evaporator
flow rate. For systems with a rapidly changing load profile
the volume should be increased.
If the installed system volume does not meet the above
recommendations, the following items should be given
careful consideration to increase the volume of water in
the system and, therefore, reduce the rate of change of the
return water temperature.
•
A volume buffer tank located in the return water piping.
•
Larger system supply and return header piping (which
also reduces system pressure drop and pump energy
use).
Minimum Water Volume for a
Process Application
If a chiller is attached to an on/off load such as a process
load, it may be difficult for the controller to respond quickly
enough to the very rapid change in return solution
temperature if the system has only the minimum water
volume recommended. Such systems may cause chiller
low temperature safety trips or in the extreme case
evaporator freezing. In this case, it may be necessary to
add or increase the size of the mixing tank in the return
line.
Unit Piping
See
"Piping System Flushing Procedure," p. 53
information on piping system flushing procedure, and
water treatment requirements.
Exchanger Water Pressures
NOTICE
Vessel Damage!
To prevent pressure vessel damage, do not exceed unit
nameplate water-side pressures.
If field installed gauges are used, provide shutoff valves in
the line(s) to the gauge(s) to isolate the gauges when not in
use.
24
Flow Sensing Devices
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.
Chilled water flow switch, or other factory approved flow
proving device is mandatory; field installation by
contractor is required. Flow switch is to be installed and
maintained per manufacturer's recommendations and
interconnected to the control panel as described on the
wiring diagram. To provide additional chiller protection,
install and wire the flow switch in series with chilled water
pump interlock for the chilled water circuits. See
Chilled Water Flow Switch," p.
schematic wiring diagrams ship with the unit inside the
control box and in this IOM notebook.
Water Piping Recommendations
All water piping must be cleaned and flushed according to
"Piping System Flushing Procedure," p. 53
circulating any water through unit.
Make sure water piping connections to the evaporator and
condenser are isolated, and confirm that all piping to unit
is supported independently to prevent any load being
transferred to the unit. Use unions, flanges or grooved lock
for
type fittings to facilitate service procedures. Use a pipe
sealant such as Teflon
connections. Use vibration eliminators to prevent
transmitting vibrations through the water lines. Construct
and install piping in accordance with all local, state and
national codes.
Supply and insulate the chilled water piping as required, to
prevent sweating and minimize heat gain under normal
operating conditions. Chilled water piping must rise above
the chiller to ensure the evaporator is full of water and void
of air at all times. Install thermometers in the lines to
monitor evaporator entering and leaving water
temperatures.
CICD chillers have manual balancing ball-valves in the
entering water lines. They may be used to establish a
balanced water flow. Both the entering and leaving water
lines have valves that can be used to shutoff/isolate the
evaporator and condenser for service.
NOTICE
"Required
32. Specific connection and
prior to
®
tape on all threaded water
CG-SVX044B-EN
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