www.DaikinApplied.com 17 IOM 1207-6 • TRAILBLAZER
®
MODEL AGZ CHILLERS
Flow Switch
All chillers require a chilled water ow switch to check that
there is adequate water ow through the evaporator and to
shut the unit down if necessary to avoid evaporator freeze-up
under low or no ow conditions. A factory-included thermal
dispersion ow switch will be installed on packaged models.
On remote evaporator models, the ow switch may be
separately eld-provided, or optionally shipped loose for eld
installation. Terminals are provided in the unit control center for
eld mounting and wiring of the water ow switch as shown on
the eld wiring diagrams, page 65 and page 66. Mount
the ow switch in the leaving water line to shut down the unit
when water ow is interrupted. A ow switch is an equipment
protection control and should never be used to cycle a unit.
Installation should be per manufacturer’s instructions included
with the switch. Flow switches should be calibrated to shut o
the unit when operated below the minimum listed ow rate for
the unit as listed on page 19. Flow switch installation and
calibration is further discussed on page 124.
There is also a set of normally closed contacts on the switch
that can be used for an indicator light or an alarm to indicate
when a “no ow” condition exists. Freeze protect any ow
switch that is installed outdoors. Dierential pressure switches
are not recommended for outdoor installation. They can freeze
and not indicate a no-ow condition.
The use of glycol may impact system performance depending
on its concentration and should be considered during initial
system design. When glycol is added to the chilled water
system for freeze protection, recognize that the refrigerant
suction pressure will be lower, cooling performance less,
and water side pressure drop will be higher. The reduction
in performance depends upon the glycol concentration and
temperature.
CAUTION
The installed glycol level must align with the rated glycol
percentage indicated on the submitted chiller technical data
sheet. Failure to adhere to the rated glycol percentage may
result in unit damage and loss of unit warranty.
Test coolant with a clean, accurate glycol refractometer to
determine the freezing point. Reset the freezestat setting to 6
°F (3.3 °C) below the leaving chilled water setpoint temperature
after the glycol percentage is veried safe for the application.
CAUTION
Do not use an automotive-grade antifreeze. Industrial
grade glycols must be used. Automotive antifreeze contains
inhibitors which will cause plating on the copper tubes within
the chiller evaporator. The type and handling of glycol used
must be consistent with local codes.
Low Ambient Operation
Compressor staging is adaptively determined by system load,
ambient air temperature, and other inputs to the MicroTech
®
III
control. The standard minimum ambient temperature is 32°F
(0°C). A low ambient option with fan VFD allows operation
down to -10°F (-23°C). The minimum ambient temperature
is based on still conditions where the wind is not greater
than 5 mph. Greater wind velocities will result in reduced
discharge pressure, increasing the minimum operating
ambient temperature. Field installed louvers are available and
recommended to help allow the chiller to operate eectively
down to the ambient temperature for which it was designed.
High Ambient Operation
Trailblazer
®
units for high ambient operation (105°F to 125°F,
41°C to 52°C) require the addition of the optional high ambient
package that includes a small fan with a lter in the air intake
to cool the control panel.
All units with the optional VFD low ambient fan control
automatically include the high ambient option. Note that in
cases of high ambient temperature, capacity could be reduced
or the lowest leaving water temperature settings may be
outside of the chiller operating envelope; consult Daikin Tools
to ensure chiller is capable of the required lift.
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