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Cutoff (DHCS) of 125°F for 10 minutes for gas heat or 90°F for
electric heat, the unit will shut down and require manual restart.
Outdoor Air Temperature and Relative
Humidity Sensor
This factory installed combination outdoor air sensor located in
the outdoor air hood is designed to sense both outdoor air
temperature and relative humidity for use by the
microprocessor controller to make required ventilation,
cooling, dehumidification and heating decisions. Control Input
(Occupied / Unoccupied)
Terminals are provided on the terminal strip labeled OAUTS for
a field installed dry contact or switch closure to put the unit in
the Occupied or Unoccupied modes.
Hot Gas Reheat
This option shall consist of a hot-gas reheat coil located on the
leaving air side of the evaporator.
100 Percent Outdoor Air Hood with
Damper and Filters
Factory-installed and -integrated 100 percent outdoor air hood
with damper controlled by a direct coupled actuator and 2 in.
(50.80 mm) permanent and washable aluminum mesh filters
(mist eliminators) removable through a hinged access panel.
The unit can be factory provided with an optional 100 percent
return air damper controlled by a direct coupled actuator that
is electrically interlocked with the outdoor air damper.
Modulating Indirect Fired Gas Burner
The unit will have fully modulating, high turndown, indirect fired
gas heat. The heating section will include high turn-down
burners and a stainless steel tubular heat exchanger. The heat
exchanger will be constructed of type 439 stainless steel and
be a tubular design capable of draining internal condensate.
External flue to be constructed of type 304 stainless steel.
Units will be suitable for use with natural gas or Liquid Propane
(LP) gas.
Through the Base Electrical with
Disconnect Switch
Factory installed 3-pole, molded case disconnect switch with
provisions for through the base electrical connections will be
included. The disconnect switch, with integral overcurrent
circuit breaker, will be installed in the unit in a water tight
enclosure with access through a hinged door. Factory wiring
will be provided from the switch to the unit high voltage terminal
block. The switch will be UL/CSA agency recognized.
Through the Base Gas Piping
The unit will include provisions for installing through the base
gas piping. The factory installed option will have all piping
necessary including an external shut-off piping yoke with pre-
assembled, manual gas shut-off valve, elbows, and union. The
manual shut-off valve will include an 1/8 in. (3.17 mm) NPT
OAU-SVX007A-EN
pressure tap. This assembly will require minor field labor to
install.
Hinged Access Doors
Hinged access doors with hold open brackets will be factory-
installed.
Modulating Electric Heat
The unit may have four stage or fully modulating SCR
controlled electric heat. The primary heating section will
include open coil heating elements, automatic and manual cut-
outs, low voltage controls, air proving switch, maximum
48 amps per circuit and fusing for heaters over 48 amps. For
ductwork installation, refer to
Supply and Exhaust Piezo Fan Rings
airflow monitoring measuring fan suction and cone pressure
differential to calculate fan airflow.
ERV
Energy Recovery Wheels rotate between the incoming
outdoor air stream and the building exhaust air stream. As the
wheel rotates, it transfers a percentage of the heat and
moisture differential from one air stream to the other. Instead
of wasting energy in the exhaust airstream, it is temporarily
captured by the energy transfer media and then released to
preheat, pre-cool, humidify, or dehumdify the incoming air.
Hot Water Coils
This option consist of a hot water coil located in the primary
heat position. Hot water valve is field provided.
Suction Pressure Monitoring
All units with compressors will come standard with a
refrigeration suction pressure transducer on Circuit 1, and on
Circuit 2 when the unit has a digital scroll on the second circuit.
Outdoor and Return Air Dampers
2-Position Outdoor Air Damper
2-position outdoor air damper without a return air damper is an
open/close damper that is energized with 24VAC when the unit
begins its startup sequence and energies the coil on the OADR
relay. There is an end switch wired back to the controller,
factory set to close at 30-50% damper position, using a rotary
dial on the actuator, to begin the supply fan sequence. The
damper should remain closed while the unit is off, with or
without power.
2-Position Outdoor and Return Air Dampers
2-position outdoor and return air dampers are open/close
dampers energized with 24VAC. Each actuator is connected to
the OADR relay, with the outdoor air damper on the normally
open (NO) and the return air damper on the normally closed
(NC). With no power on the unit, both dampers are closed. As
the unit is powered, the NC contact is closed, and the return air
damper opens. Once the startup sequence begins and OADR
General Information
"Ductwork," p.
74.
19
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