Daikin DPSA Manual page 40

G. Each unit shall have two independent refrigeration
circuits for redundancy. Each circuit shall be
complete with a low pressure control, filter-drier,
liquid moisture indicator/sight-glass, thermal
expansion valve, and a manual reset high pressure
safety switch. The thermal expansion valve shall
be capable of modulation from 100% to 25% of its
rated capacity. Sight-glasses shall be accessible
for viewing without disrupting unit operation. Each
circuit shall be dehydrated and factory charged with
Refrigerant 410A and oil.
H. Option for sizes 20-50 – Each unit shall have at least
4 compressor stages of cooling capacity control
for better part load control as required by ASHRAE
90.1-2013.
2 .22 Roof Curbs
A. A prefabricated 12-gauge galvanized steel, mounting
curb, designed and manufactured by the unit
manufacturer, shall be provided for field assembly
on the roof decking prior to unit shipment. The roof
curb shall be a full perimeter type with complete
perimeter support of the air handling section and
rail support of the condensing section. Supply and
return opening duct frames shall be provided as part
of the curb structure allowing duct connections to
be made directly to the curb prior to unit arrival. The
curb shall be a minimum of 20" high and include a
nominal 2"×4" wood nailing strip. Gasket shall be
provided for field mounting between the unit base
and roof curb.
2 .23 Controls
A. Each unit shall be equipped with a complete
MicroTech 4 microprocessor based control system.
The unit control system shall include all required
temperature and pressure sensors, input/output
boards, main microprocessor and operator interface.
All boards shall be individually replaceable for ease
of service. All microprocessors, boards, and sensors
shall be factory mounted, wired and tested.
B. The microprocessor shall be a stand-alone DDC
controller not dependent on communications with
any on-site or remote PC or master control panel.
The microprocessor shall maintain existing set
points and operate stand alone if the unit loses
either direct connect or network communications.
The microprocessor memory shall be protected
from voltage fluctuations as well as any extended
power failures. All factory and user set schedules
and control points shall be maintained in nonvolatile
memory. No settings shall be lost, even during
extended power shutdowns.
C. The main microprocessor shall support an RS-232
direct connection to a product service tool or a
modem. A communications module shall be provided
for direct communication into the BAS network.
CAT 258 • REBEL APPLIED ROOFTOP
D. All digital inputs and outputs shall be protected
against damage from transients or wrong voltages.
Each digital input and digital output shall be
equipped with an LED for ease of service. All field
wiring shall be terminated at a separate, clearly
marked terminal strip.
E. The microprocessor shall have a built-in time
schedule. The schedule shall be programmable from
the unit keypad interface. The schedule shall be
maintained in nonvolatile memory to insure that it is
not lost during a power failure. There shall be one
start/stop per day and a separate holiday schedule.
The controller shall accept up to sixteen holidays
each with up to a 5-day duration. Each unit shall
also have the ability to accept a time schedule via
BAS network communications.
F. If the unit is to be programmed with a night setback
or setup function, an optional space sensor shall
be provided. Space sensors shall be available to
support field selectable features. Sensor options
shall include Zone sensor with tenant override
switch, or Zone sensor with tenent override switch
and heating/cooling set point adjustment.
2 .24 Warranty
A. The manufacturer shall provide 12 month parts
only warranty. Defective parts will be repaired or
replaced during the warranty period at no charge.
The warranty period shall commence at start up, or
6 months after shipment, which ever occurs first.
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General Specification
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