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It is recommended that the field installed water piping to the
chiller include:
• Thermometers at the inlet and outlet connections of the
evaporator.
• Water pressure gauge connection taps and gauges at
the inlet and outlet connections of the evaporator for
measuring water pressure drop.
• Shutoff valves to isolate the unit from the piping during
unit servicing.
• Minimum bends and changes in elevation to minimize
pressure drop.
• An expansion tank and regulating valve to maintain
adequate water pressure. Tank becomes required
for closed loop systems based on water volume and
temperature ranges.
• Vibration eliminators in both the supply and return water
lines to reduce transmissions to the building.
• Flushing the system water piping thoroughly before
making connections to the unit evaporator.
• Piping insulation, including a vapor barrier, helps prevent
condensation and reduces heat loss.
• Regular water analysis and chemical water treatment
for the evaporator loop is recommended immediately at
equipment startup.
Inlet Strainer Guidelines
An inlet water strainer kit must be installed in the chilled water
piping within 5 feet of the evaporator inlet or IWSE connection.
Two paths are available to meet this requirement:
1. A field-installed kit shipped loose with the unit is available
for all unit sizes and consists of:
• Y-type area strainer with 304 stainless steel perforated
basket, Grooved pipe connections and strainer cap
— a strainer with perforations no larger than 0.031"
(1/32", 0.8 mm) diameter for AWV models with the
IWSE option along with a gasket and bolts...see
Figure 38
for installation.
— a strainer with perforations no larger than 0.063"
(1/16", 1.6 mm) diameter for AWV models with a
braze plate evaporator
— a strainer with perforations no larger than 0.125"
(1/8", 3.2 mm) diameter for AWV models with a direct
expansion evaporator
• Extension pipe with two couplings that may be used
for gauges and sensors. The pipe provides sufficient
clearance from the evaporator for strainer basket
removal (non-IWSE configurations).
• ½-inch blowdown valve (non-IWSE configurations)
• Two grooved clamps (non-IWSE configurations)
The strainer is sized per
Table
the Pressure Drop Data section on
2. A field-supplied strainer to same specifications as factory
installed option.
IOM 1242-8 • PATHFINDER
2. Connection sizes are given in
page
42.
MODEL AWV CHILLERS
®
Installation and Application Considerations
Table 2: Strainer Sizing Data
Strainer
Application
Size (in .)
6
IWSE
8
10
Braze Plate
6
Evap
6
Shell and
8
Tube Evap
10
Installing Inlet Strainer (Field-installed Kit)
The strainer must be mounted per manufacturer's instruction
with the arrows in the direction of flow; inlet and outlet are
noted along with the arrows. The piping and strainer must be
supported to prevent any stress on the evaporator nozzle.
Non-IWSE units - The extension pipe is only for non-IWSE
units and is located adjacent to the evaporator with the strainer
then mounted to it. Use one grooved clamp to mount the
extension pipe to the evaporator and the second to mount the
strainer to the pipe. The clamps to mount the field piping to the
strainer are field supplied.
IWSE Units - Place the supplied gasket between the gasket
seating surface of the inlet IWSE pipe and the strainer flange
as shown in
Figure
38. Secure with provided bolts and nuts.
Figure 38: IWSE Gasket Connection to Strainer
System Water Volume
All chilled water systems need adequate time to recognize a
load change, respond to that load change and stabilize, without
undesirable short cycling of the compressors or loss of control.
In air conditioning systems, the potential for short cycling
usually exists when the building load falls below the minimum
chiller plant capacity or on close-coupled systems with very
small water volumes. Some of the things the designer should
consider when looking at water volume are the minimum
cooling load, the minimum chiller plant capacity during the low
load period and the desired cycle time for the compressors.
18
Maximum
Strainer
Perforation Size
Weight
in . (mm)
(lbs)
154
0.031"
273
(1/32", 0.8 mm)
464
0.063"
120
(1/16", 1.6 mm)
120
0.125"
220
(1/8", 3.2 mm)
514
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