AAON RN Series, Installation, Operation & Maintanance Manual, Page: 64 / 116

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maintain the setpoint ‘LATset’ to a
maximum number of stages set in setpoint
‘Stages’.
If a safety is reached with the controller’s
safety sensors then the electric preheat will
be de-energized for a period of 2 minutes.
Electric preheat will turn on stage one at
100% for 3 minutes to test if fault conditions
still exist after the cool down period. The
controller will repeat this and if 3 trips are
recorded in 60 minutes then the controller
will lockout and require manually cycling
power to reset.
The modulating electric preheat option is
designed to temper the incoming outside air
to the unit based on an enable control signal
and the outside air conditions.
A 24VAC enable signal must be provided to
the [PHE] terminal to enable the operation
of the electric preheat. Once the preheat
controller is enabled it will monitor the
outside air temperature to determine if any
capacity of preheat is needed. If the outside
air temperature falls below the outside air
temperature setpoint the electric preheat will
be started up and maintain the leaving air
temperature
setpoint with both SCR
controlled and staged electric preheat. Both
setpoints are set with push button LCD
interface on the preheat controller. Outside
air temperature sensors and preheat
discharge supply air temperature sensors are
factory installed and wired to the preheat
controller. Electric preheat has maximum
operating outside air temperature of 60°F
and a maximum preheat discharge air
temperature of 80°F.
[COM], [PHO] & [PHC] feedback terminals
are provided to communicate if the electric
preheat is in operation. PHO is a normally
open contact, PHC is a normally closed
contact, and COM is the common. These
terminals are not required to be connected.
[PHE] is the electric preheat operation
enable. [PH+] and [PH-] are the preheat set
point reset terminals.
Energy Recovery Units
General Information
AAONAIRE® units have been equipped
with an energy recovery wheel. This section
is provided to assure the energy recovery
feature will be properly setup to perform in
accordance with the job specifications for
your particular application.
Energy Recovery Wheel
The Energy Recovery Cassette consists of a
frame wheel, wheel drive system, and
energy transfer segments. Segments are
removable for cleaning or replacement. The
segments rotate through counter flowing
exhaust and outdoor air supply streams
where they transfer heat and/or water vapor
from the warm, moist air stream to the
cooler and/or drier air stream.
Improper installation, adjustment,
alteration, service or maintenance
can cause property damage,
personal injury or loss of life. Startup
and service must be performed by a
Factory Trained Service Technician.
WARNING