036-21411-002-A-0204
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Unitary Products Group
voltage terminal strip. An additional set of pin connectors is
also provided to simplify the field interface of external con-
trols. Mate--n--lock plug connectors are used where line and
low voltage wires pass through internal bulkheads. This
allows for easier troubleshooting and component replace-
ment. The electrical control box is not located in the compres-
sor compartment so the access cover can be removed for
troubleshooting without affecting the normal system operat-
ing pressures.
AIR FILTERS -- Units are shipped with 1" throwaway filters.
The unit filter racks can accommodate 1" or 2" filters without
any modifications.
FACTORY-INSTALLED OPTIONS
ECONOMIZERS: Units equipped with a factory-installed
economizer option have dampers that are positioned by a
spring return, fully modulating damper actuator and are capa-
ble of introducing up to 100% outdoor air. As the outdoor air
intake dampers open, the return air dampers close. The
changeover from mechanical refrigeration to economizer
operation is determined by a single input electronic enthalpy
control or by a dual input electronic enthalpy control. Simulta-
neous compressor and economizer operation is also possi-
ble.
The single enthalpy system contains a sensor that monitors
the outdoor air which automatically operates the damper
actuator allowing the dampers to open or close.
The dual enthalpy system contains a second sensor that
monitors both the temperature and the humidity of the return
air in addition to the outdoor air sensor described for a single
enthalpy system. The logic module compares the inputs from
both sensors and switches to economizer operation when-
ever the outdoor air is cooler than the return air for maximum
efficiency of the economizer system.
The economizer is completely wired and installed at the fac-
tory. Only the outdoor air hood, including its filters, need be
assembled and installed in the field.
BELT DRIVE BLOWERS: Adjustable belt-drive blowers pro-
viding maximum flexibility to handle many airflow require-
ments, are available on all models.
FIELD-INSTALLED ACCESSORIES
SINGLE INPUT ELECTRONIC ENTHALPY ECONOMIZER -
Includes a slide-in / plug-in damper assembly with fully modu-
lating spring return motor actuator capable of introducing up
to 100% outdoor air, one outdoor air electronic enthalpy sen-
sor and a rain hood with filters. The rain hood is painted to
match the basic unit and must be field-assembled before
installation. Economizer dampers are 2% low leakage type.
DUAL INPUT ELECTRONIC ENTHALPY ECONOMIZER -
Includes the same damper system and rain hood with filters
as described for a single enthalpy economizer except this
accessory contains two enthalpy sensors. It uses a differen-
tial enthalpy control that compares the outdoor air versus the
return air. The logic module then optimizes the economizer
operation for additional savings over the single input econo-
mizer.
MOTORIZED AIR DAMPER - Includes a slid-in/plug-in
damper assembly with a rainhood and filters. The outdoor air
dampers open when the indoor fan motor is energized. The
damper is capable of providing 0% through 100% of outdoor
return air opening.
MANUAL OUTDOOR DAMPER - Provides 0% through 35%
or 0% through 100% of return air opening (field adjustable).
Designed for duct mounted side or bottom supply/return
applications. Includes rain hood assembly and filter.
ELECTRIC HEATERS - Include nickel chromium elements, a
terminal block, fuses (where required by UL), all the neces-
sary connectors and hardware. All heaters utilize single point
power supply hookup. Capacities from 5 KW through 30 KW
heating are available.
FUSE BLOCK KITS - These kits have a fuse box with a fuse
block and fuses. They're available for all 460-3-60 volt heat-
ers and 208/230-3-60 volt heaters 7 KW and smaller.
OUTDOOR THERMOSTAT - A 24-volt thermostat providing
two stages of control for units equipped with electric heat
accessories.
ROOF CURB - This 14" high full perimeter roof curb is
shipped knocked down for field assembly and contains duct
supports that can easily be shifted for the desired unit duct
arrangement. No insulated deck is required because the unit
underside is insulated.
START ASSIST KIT - Provides increased starting torque for
single phase units in areas with low voltage conditions. It con-
tains a 12.5 OHM PTCR temperature resistor with a support
clip and hardware for mounting.
LOW AMBIENT KIT - A head pressure controller maintains
stable system operation by reducing the speed of the con-
denser fan motor when the outdoor temperature is between
45 and 0 ºF. Condenser fan motors with ball bearings and
heavier windings are also available for these low ambient
applications.
ANTI-RECYCLE TIMER - A timer to prevent the unit com-
pressor from short cycling. It assures a 5-minute off-time
between compressor cycles.
