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All supply air blowers are equipped with a belt drive
that can be adjusted to meet the exact requirements of
the job. A high speed drive accessory is available for
applications with a higher CFM and/or static pressure
requirement.
All compressors include internal pressure relief. Every
refrigerant circuit includes an expansion valve, a liquid
line filter-drier, a discharge line high pressure switch
and a suction line with a freezestat and low pressure/
loss of charge switch. The unit control circuit includes
two 75 VA transformers, two 24-volt circuit breakers
and a relay board with two compressor lockout circuits,
a terminal strip for thermostat wiring, plus an additional
set of pin connectors to simplify the interface of addi-
tional field controls.
All 208/230 and 460-volt models are ETL approved. All
208/230 and 575-volt models are CGA approved.
All models include a 1-year limited warranty on the
complete unit. Compressors and electric heater ele-
ments carry an additional 4-year warranty. Aluminized
steel tubular heat exchangers carry an additional 9-
year warranty.
All gas heat models are built with two heating sections
for two equal stages of capacity control. Each section
includes a durable heat exchanger with aluminized
steel tubes, a redundant gas valve, spark ignition,
power venting, an ignition module for 100% shut-off
and all of the safety controls required to meet the latest
ANSI standards.
The gas supply piping can be routed into the heating
compartment through a hole in the base pan of the unit
or through a knockout in the piping panel on the front of
the unit.
All electric heat models are wired for a single power
source and include a bank of nickel chromium ele-
ments mounted at the discharge of the supply air
blower to provide a high velocity and uniform distribu-
tion of air across the heating elements. Every element
is fully protected against excessive current and temper-
ature by fuses and two thermal limit switches.
The power supply wiring can be routed into the control
box through a threaded pipe connection in the base
pan of the unit or through a knockout in the wiring
panel on the front of the unit.
All internal factory wiring is color coded and numbered
for ease in servicing and troubleshooting.
2
FACTORY-INSTALLED OPTIONS
ECONOMIZERS
Interlocked outdoor and return air dampers are posi-
tioned by a fully modulating, spring return damper actu-
ator capable of introducing up to 100% outdoor air with
nominal 1% leakage type dampers. As the outdoor air
intake dampers open, the return air dampers close.
The changeover from compressor to economizer cool-
ing is determined by one or two solid state enthalpy
controls.
On single enthalpy, an outdoor air sensor determines
when the outdoor air is cool and dry enough to provide
"free" cooling. On differential enthalpy, one sensor
monitors the outdoor air while a second sensor moni-
tors the return air. Whenever the outdoor air is cooler
and drier than the return air, the unit will switch to econ-
omizer operation. For either option, the first compres-
sor stage can provide additional cooling during
economizer operation if the room thermostat calls for
second stage.
The dampers and controls are installed and wired at
the factory. Only the accessory rain hood needs to be
assembled and installed in the field.
These economizer options can be used on all duct con-
figurations.
POWER EXHAUST
Both the single and differential economizer options are
available with power exhaust. Whenever the outdoor
air intake dampers are opened for free cooling, the
exhaust fan will be energized to prevent the condi-
tioned space from being over-pressurized during econ-
omizer operation.
The exhaust fan, motor and controls are installed and
wired at the factory. Only the back-draft damper
assembly needs to be field installed and the accessory
rain hoods need to be assembled and installed in the
field.
The power exhaust option can only be used on bottom
duct configurations.
MOTORIZED OUTDOOR AIR INTAKE DAMPER
Interlocked outdoor and return air dampers are con-
trolled by a 2-position, spring return damper actuator.
The outdoor damper will open to some pre-set position
whenever the supply air blower is operating and will
drive fully closed when the blower shuts down.
The damper and controls are installed and wired at the
factory. Only the accessory rain hood needs to be
assembled in the field.
This damper option can be used on all duct configura-
tions.
036-21359-001-B-0302
Unitary Products Group
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