LG Multi V ARNU093TUD4 Engineering Manual page 54

FOUR-WAY CEILING CASSETTE
Mechanical Speci cations
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. 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-supplied
all-thread rod hangers.
Ventilation Air
TQ, TR Frame
The case has a factory designated cutout for the connection of a
field-supplied outside air duct. An optional flange kit is available from
LG.
TM, TN, TP Frame
The case has a factory designated cutout for the connection of a
field-supplied outside air duct. LG offers two flange kits.
Supply Air Branch Duct Connections
Factory designated cutouts are marked on the unit case. Branch
ducts provide the designer with the ability to duct up to 1/2 the unit
airflow capacity to adjacent spaces. The adjacent space must be
in the room where the ceiling cassette is installed. It cannot be
branched to another room.
Architectural Filter/Grille
The ceiling cassette assembly is provided with an off-white ABS
polymeric resin architectural grille equipped with a tapered trim edge
and a hinged, spring clip (screwless) return air filter-grille door.
TM, TN, TP Frame
The unit case allows access to hanger rods and the inspection of
piping through corner access panels on the architectural grille. The
optional auto-elevating grille kit is designed to provide motorized
ascent/descent of the return air grille/pre-filter assembly a distance
of up to 14-3/4 feet allowing easy access to remove and clean the
filter.
The kit consists of two lifting mechanisms comprised of an electric
motor driven winch with braided steel lifting cables. The winch kit
is mounted behind the grille and is not visible during normal unit
operation. The auto-elevating return air grille appearance and finish
matches that of the architectural grille on similar indoor unit models
equipped with the standard hinged filter grilles. The auto-elevating
grille control algorithm accepts up, down, and stop control com-
mands from either a wall-mounted or the lift remote controller. The
algorithm does not permit the lowering of the grille while the indoor
unit fan is operating. The pair of winch controllers work in unison
to keep the return air grille level during lift and descent operations
and will automatically stop the descent of the return air grille/filter if
contact is made with any obstacle.
54 | FOUR-WAY ©
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-fungal
treatment. Plasma filter accessories are also available separately.
Airflow Guide Vanes
The architectural grille has four-directional slot diffusers each
equipped with independent oscillating motorized guide vanes de-
signed to change the angle airflow is discharged. Discharge range
of motion is 40° in an up/down direction. The unit has a guide vane
control algorithm designed to sequentially change the predomi-
nant discharge airflow direction in a counterclockwise pattern. The
control algorithm also provides the capability of locking each guide
vane independently in a field adjusted fixed position. Guide vanes
provide airflow in all directions. The ends of each vane are tapered
to provide airflow to the space in the direction of the four corners of
the architectural grille.
Microprocessor Controls
The unit is provided with an integrated microprocessor controller
capable of performing functions necessary to operate the system
without the use of a wall-mounted controller. A temperature therm-
istor is factory-mounted in the return air stream. All unit operation
parameters, excluding the unit 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