Daikin Clima-Flex CLIV Series Installation, Operation And Maintenance Manual page 10

It is recommended that the field-installed water piping for the
chiller include:
• Temperature sensors at
connections.
• Water pressure gauge connection taps and pressure gauges
on evaporator inlet and outlet connections to measure water
pressure drop.
• Shut-off valves to isolate the unit from piping during unit
maintenance.
• Minimum bends and elevation changes to minimize pressure
drop.
• Vibration eliminators on supply and return water lines to
reduce transmissions to the building.
• Thorough flushing of system water piping prior to making
connections to the unit evaporator.
• Insulation of piping, including a vapor barrier, helps prevent
condensation and reduces heat loss.
• Periodic water analysis and chemical treatment of the
evaporator loop water is recommended immediately after unit
start-up.
INLET STRAINER GUIDELINES
An inlet water filter kit must be installed in the cold water piping
upstream of the evaporator inlet. There are several ways available
to meet this requirement:
1. Factory-installed option available - models 3 through 10.
2. A field installation kit shipped loose with the unit is available
for all unit sizes and consists of:
3. Y-type area strainer with 304 stainless steel perforated bas-
ket, slotted pipe connections and strainer cover [a strainer
with perforations as listed below depending on model].
4. A field supplied strainer meeting the specifications and instal-
lation requirements of this manual.
TECHNICAL DATA OF THE STRAINER
• Head and neck nut: Brass
• Filter element: Polyamide body coated with nylon mesh
• Filter cup: Trogamid T 5000 (virtually impact resistant,
pressure wave resistant, permanently transparent, stress
resistant).
• (Brass cup available on request).
• Working pressure: PN 16
• Test pressure: 25 bar
• Maximum water temperature: 30° C
• Mesh size: 95-140 μm.
• Available with and without Rp 1⁄8 pressure gauges.
Table 2. Flow rates according to DVGW test
DN 20 Rp 3⁄4 5,0 m3/h
DN 35 Rp 1 7,9 m3/h
DN 32 Rp 11⁄4 12,0 m3/h
DN 40 Rp 11⁄ 2 11.9 m3/h
DN 50 Rp 2 14,9 m3/h
iom-cliv-cf-eng
evaporator inlet and outlet
Δp = 0,2 bar:
Installation and Application Information
Figure 7. Factory installed strainer.
WATER FLOW LIMITATIONS
Constant evaporator flow
Maximum flow rate and pressure drop are based on a 6°F
temperature drop. Flow rates above the maximum values will
result in unacceptable pressure drops and may cause excessive
erosion, which could lead to failure.
The minimum flow rate and pressure drop are based on a full
load evaporator temperature drop of 16°F. Evaporator flow rates
below the minimum values can result in laminar flow leading to
low pressure alarms, fouling and poor temperature control.
Variable evaporator flow
Reducing the evaporator flow rate in proportion to the load can
reduce the energy consumption of the system. The rate of flow
change should be a maximum of 10 percent of the flow per minute.
For example, if the maximum design flow rate is 200 gpm and is to
be reduced to a flow rate of 140 gpm, the flow change is 60 gpm.
Ten percent of 200 gpm equals a change of 20 gpm per minute,
or a minimum of three minutes to go from the maximum flow to
the desired flow.
If the flow rate falls below the minimum allowable, large reductions
in heat transfer can occur. If the flow rate exceeds the maximum,
excessive pressure drop and tube erosion can occur.
System water considerations
All chilled water systems need adequate time to recognize a load
change, respond to the change and stabilize to avoid undesirable
compressor short cycling or loss of temperature control.
In air conditioning systems, the potential for short cycling often
occurs when the building load drops below the minimum capacity
of the chiller plant or in tightly coupled systems with very small
water volumes.
Some of the aspects that the designer should consider when
studying water volume are the minimum cooling load, the
minimum capacity of the refrigeration plant during the low load
period and the desired cycle time for the compressors.
Assuming there are no sudden loads and the cooling plant has
a reasonable drawdown, the rule of thumb of "water volume in
gallons equals two to three times the chilled water flow rate in
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