LG Multi V ARNU093TUD4 Engineering Manual page 37

Casing
The case is designed to mount recessed in the ceiling and has a
surface-mounted concentric grille on the bottom of the unit. The
unit case is manufactured with coated metal, and cold surfaces are
covered with a coated polystyrene insulating material. The case is
provided with metal ears designed to support the unit weight on four
corners. Ears have pre-punched holes designed to accept field-sup-
plied, all-thread rod hangers.
Ventilation Air
The case has a factory designated cutout for the connection of a
field supplied outside air duct.
Architectural Filter/Grille
The ceiling cassette assembly is provided with an off-white ABS
polymeric resin architectural grille with a tapered trim edge and a
hinged, spring clip (screw-less) return air filter-grille door.
Fan Assembly and Control
The indoor unit has a single, direct-drive, turbo fan. The fan wheel
is made of high strength ABS HT-700 polymeric resin. The fan motor
is a Brushless Digitally-Controlled (BLDC) design with permanently
lubricated and sealed ball bearings. The fan motor includes thermal,
overcurrent and low RPM protection. The fan / motor assembly is
mounted on vibration attenuating rubber grommets. The fan impeller
is statically and dynamically balanced. The fan speed is controlled
using a microprocessor-based direct digital control algorithm that
provides a high fan speed in cooling thermal ON and low fan speed
in cooling thermal OFF, high fan speed in heating thermal ON and
fan off in heating thermal OFF. The fan speeds can be field adjusted
between low, medium, and high speeds. The fan speed algorithm
provides a field selectable, fixed-speed or auto-speed setting that
adjusts the fan speed to simulate natural airflow.
Air Filter
Return air is filtered with a removable, washable filter with anti-fun-
gal treatment.
Airflow Guide Vanes
The architectural grille has two parallel directional slot diffusers each
equipped with oscillating motorized guide vanes designed to change
the angle airflow is discharged. Discharge range of motion is 40º in
an up/down direction. The control algorithm provides the capability of
locking guide vanes in a field adjusted fixed position.
TWO-WAY CEILING CASSETTE
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Mechanical Speci cations
Microprocessor Controls
The unit is provided with an inte-
grated microprocessor controller
capable of performing functions
necessary to operate the system
without the use of a wall-mount-
ed controller. A temperature
thermistor is factory-mounted
in the return air stream. All unit operation parameters, excluding the
units operating schedule, are stored in non-volatile memory resident
on the unit microprocessor. Operating schedules are stored in select
models of the optional, wall-mounted, local, or central controller. The
field-supplied communication cable between the indoor unit(s) and
outdoor unit is to be a minimum of 18 AWG, 2 conductor, stranded,
and shielded cable (RS 485), terminated via screw terminals on the
control boards. The microprocessor control provides the following
functions: auto addressing, self-diagnostics, auto restart following
power restoration, test run, and will operate the indoor unit using one
of five operating modes:
1. Auto Changeover (Heat Recovery only)
2. Heating
3. Cooling
4. Dry
5. Fan Only
For Heat Recovery systems the Auto Changeover setting
automatically switches control of the indoor unit between Cooling
and Heating modes based on space temperature conditions.
For Heat Pump systems, heated or cooled air delivery is dependent
upon outdoor unit operating mode.
In Heating mode, the microprocessor control will activate indoor unit
operation when the indoor room temperature falls below set-point
temperature. At which point, a signal is sent to the outdoor unit to
begin the heating cycle. The indoor unit fan operation is delayed until
coil pipe temperature reaches 76°F. Significant airflow is generated
when pipe temperature reaches 80°F. The unit is equipped with
an infrared receiver designed to communicate with an LG wireless
remote controller. In lieu of wireless remote or factory return air
thermistor, screw terminals on the microprocessor circuit board
accommodate various models of wall-mounted local controllers and
or wall-mounted temperature sensors. The unit microprocessor is
capable of accepting space temperature readings concurrently or
individually from either:
1. Wall-mounted wired controller(s)
2. Factory mounted return air thermistor or the optional wall mounted
wired remote temperature sensor.
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