Daikin AWV008, Installation, Operation And Maintenance Manual

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www.DaikinApplied.com 17 IOM 1242-2 • PATHFINDER
®
MODEL AWV CHILLERS
3. If the chiller does not have the ability to control the
pumps and the water system is not to be drained in
temperatures below freezing, the chiller may be subject
to catastrophic evaporator failure due to freezing. The
freeze rating of the evaporator is based on the immersion
heater and pump operation. The immersion heater itself
may not be able to properly protect the evaporator from
freezing without circulation of water.
Variable Speed Pumping
Reducing evaporator flow in proportion to load can reduce
system power consumption. Daikin Applied chillers are
designed for variable water flow duty provided that the rate of
change is less than ten percent of the design flow per minute,
and the minimum and maximum flow rates for the evaporator,
beginning on page 39 , are not exceeded. If flow drops
below the minimum allowable, large reductions in heat transfer
can occur. If the flow exceeds the maximum rate, excessive
pressure drop and tube erosion can occur. For example, if the
maximum design flow is 200 gpm and it will be reduced to a
flow of 140 gpm, the change in flow is 60 gpm. Ten percent of
200 gpm equals 20 gpm change per minute, or a minimum of
three minutes to go from maximum to desired flow.
Ice Mode
Optional double evaporator insulation is recommended for ice
mode operation. The standard controller software will require
“ice” set point changes and a digital signal into the controller
is required to change to the ice mode and back to standard
cooling. See the Field Wiring Diagrams on page 19 and
page 20 for the connection location. In ice mode, the unit
will operate at full load until the shutoff temperature set point is
reached.
Glycol Solutions
Test coolant with a clean, accurate glycol solution hydrometer
(similar to that found in service stations) or refractometer to
determine the freezing point. Obtain percent glycol from the
freeze point table on page 84. On glycol applications, the
supplier normally recommends that a minimum of 25% solution
by weight be used for protection against corrosion or that
additional inhibitors should be employed.
CAUTION
Do not use automotive grade antifreeze. Industrial grade
glycols must be used. Automotive antifreeze contains
inhibitors that will cause plating on the copper tubes within the
chiller evaporator. The type and handling of glycol used must
be consistent with local codes.
Performance Adjustment Factors
AWV chillers are designed to operate with leaving antifreeze
solution temperatures per software range limits. Consult the
local Daikin Applied sales office for performance outside
these temperatures. Leaving chilled fluid temperatures below
40°F (4.4°C) result in evaporating temperatures at or below
the freezing point of water and a glycol solution is required.
MicroTech
®
III control inhibits compressor unloading at leaving
fluid temperatures below 25°F (-3.9°C).
Low fluid temperatures or high equipment room humidity for
remote evaporators may require optional double evaporator
insulation. The system designer should determine its necessity.
The use of glycol will reduce unit performance depending on its
concentration and should be considered during initial system
design.
Electrical Connections
Pathfinder
®
units can be ordered with either standard multi-
point power or optional single point power connections and
with various disconnect and circuit breaker options. Power
wiring connections to the chiller may be done with either
copper or alumninum wiring. All wiring must be done in
accordance with applicable local and national codes. Wiring
within the unit is sized in accordance with the NEC
®
. Refer to
the unit nameplate and the unit selection report for the correct
electrical ratings.
DANGER
Qualified, licensed electricians must perform wiring. Electrical
shock hazard exists that can cause severe injury or death.
The field power wiring required varies depending on unit
model. See page 19 and page 20 for wiring information.
These wiring diagrams are also provided with the chiller.
NOTE:
Wiring, fuse, and wire size must be in accordance
with the NEC
®
. The voltage to these units must be
within ± 10% of nameplate voltage (415V units must
have voltage within -13% and +6% of nameplate
voltage) and the voltage unbalance between phases
must not exceed 2%. Since a 2% voltage unbalance
will cause a current unbalance of 6 to 10 times the
voltage unbalance per the NEMA MG-1 Standard, it
is most important that the unbalance between phases
be kept at a minimum.
CAUTION
Do not use power factor correction capacitors with AWV
chillers. Doing so can cause harmful electrical resonance in
the system. Correction capacitors are not necessary since
VFDs inherently maintain high power factors.
Table 3: SCCR Ratings (kAmps)
Voltage/Hz
Standard Short
Circuit Panel Rating
High Short Circuit
Panel Rating
380/60 10kA 65kA
460/60 10kA 65kA
575/60 5kA 25kA
400/50 10kA 65kA
Field-supplied disconnect switches are required if not factory-
supplied with the unit. Disconnecting means are addressed by
Article 440 of the NEC ® , which requires “disconnecting means
capable of disconnecting air conditioning and refrigerating