Microprocessor Control - LG AR-DR12-05A Installation And Operation Manual

OPTIONAL COMPONENT OPERATION
Timed Exhaust Frost Control
Timed exhaust frost control includes a timer in addition to the thermodisc and wheel pressure sensor. When timed exhaust frost control is
initiated, the timer will turn the supply blower off. Time exhaust using default timer setting will shut down the supply fan for 5 minutes every
30 minutes to allow exhaust to defrost energy wheel. Use the test procedure in the Optional Start-Up Accessories section for troubleshooting.
Electric Preheat Frost Control
Electric preheat frost control includes an electric heater (at outdoor air intake) in addition to the thermodisc and pressure sensor on wheel.
When electric preheat frost control is initiated, the electric preheater will turn on and warm the air entering the energy wheel to avoid frosting.
Use the test procedure in the Optional Start-Up Accessories section for troubleshooting.
Modulating Wheel Frost Control
Modulating wheel frost control includes a variable frequency drive (VFD) in addition to the thermodisc and pressure sensor. When modulating
wheel frost control is initiated, the VFD will reduce the speed of the wheel. Reducing the speed of the energy wheel reduces its effective-
ness, which keeps the exhaust air condition from reaching saturation, thus, eliminating condensation and frosting. If the outdoor air tempera-
ture is greater than the frost threshold temperature OR the pressure differential is less than the set point, the wheel will run at full speed. If
the outdoor air temperature is less than 5°F AND the pressure differential is greater than the set point, the wheel will run at reduced speed
until the pressure differential falls below the set point. The VFD will be fully programmed at the factory.
Rotation Sensor
The rotation sensor monitors energy wheel rotation. If the wheel should stop rotating, the sensor will close a set of contacts in the unit control
center. Field-wiring of a light (or other alarm) between terminals R and 12 in the unit control center will notify maintenance personnel when a
failure has occurred.
Dirty Filter Sensor
Dirty filter sensors monitor pressure drop across the outdoor air filters, exhaust air filters, or both. If the pressure drop across the filters
exceeds the set point, the sensor will close a set of contacts in the unit control center. Field-wiring of a light (or other alarm) to these contacts
will notify maintenance personnel when filters need to be replaced. The switch has not been set at the factory due to external system losses
that will affect the switch. This switch will need minor field adjustments after the unit has been installed with all ductwork complete. The dirty
filter switch is mounted in the exhaust inlet compartment next to the unit control center or in unit control center.

Microprocessor Control

The microprocessor controller is specifically designed and programmed to optimize the performance of
the unit with supplemental heating and cooling. This option ensures that the outdoor air is conditioned to the desired discharge conditions.
The controller and accompanying sensors are factory-mounted, wired and programmed. Default settings are pre-programmed, but are easily
field-adjustable.
The microprocessor controller can be interfaced with a Building Management System through LonWorks®, BACnet®, or ModBus. Please
refer to the Installation, Operation and Maintenance manual for detailed information.
Unoccupied Recirculation Damper
The unoccupied recirculation option provides a recirculation damper from the return air intake to the supply airstream. If equipped with a
room temperature and/or relative humidity sensor, the unit can cycle on to maintain unoccupied room set points if there is a call for unoccu-
pied heating, cooling, or dehumidification. During the unoccupied mode, the supply and exhaust (if equipped) fans will be off unless there is a
call for cooling, heating, or dehumidification in the space.
Vapor Tight Lights
Vapor tight lights provide light to each of the compartments in the energy recovery unit. The lights are wired to a junction box mounted on the
outside of the unit. The switch to turn the lights on is located in the unit control center. The switch requires a separate power source to allow
for power to the lights when the unit main disconnect is off for servicing.
Due to our policy of continuous product innovation, some specifications may change without notification.
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