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Indoor Return Airflow
A non-restrictive path for room air returning to the
center section of the unit must be provided inside
the room. Avoid placing objects including furniture,
electronics equipment, equipment racks and cabinets
directly in front of the unit return grilles and registers.
Bard recommends at least 2' between solid objects
and return grilles or registers. Ductwork may be used to
ensure proper air circulation and all provided ductwork
guidelines and clearances must be followed. Non-
ducted applications must use a return louver grille
installed over the return opening inside the room.
Ducted Applications
Field fabricated supply and return duct work may be
installed inside the structure being conditioned. A short
supply and/or return stub duct may be connected to the
unit supply and return flanges before unit installation to
help with duct connections inside the structure. Supply
and return ducts must be properly sized for the design
airflow requirement of the equipment. Air Conditioning
Contractors of America (ACCA) is an excellent guide to
proper sizing. All duct work or portions thereof not in the
conditioned space should be properly insulated in order
to conserve energy, reduce heat conductivity, and prevent
condensation or moisture damage. Refer to Maximum
External Static Pressure (ESP) of Operation Table 17 on
page 45. Design the duct work according to methods
given by the Air Conditioning Contractors of America
(ACCA). When duct work is installed in unheated spaces,
it should be insulated with a minimum of 1" of insulation.
Use insulation with a vapor barrier on the outside of the
insulation. Flexible joints should be used to connect the
duct work to the equipment in order to keep the noise
transmission to a minimum. Ducts through the walls must
be insulated and all joints taped or sealed to prevent air
or moisture from entering the wall cavity.
The unit itself is suitable for 0" clearance, but the
supply air duct flange and the first 3' of supply air duct
require a minimum of 1/4" clearance to combustible
material for all models. However, it is generally
recommended that a 1" clearance is used for ease of
installation and maintaining the required clearance to
combustible material. See Figures 3A and 3B on pages
17 and 18 for details on opening sizes.
WARNING
!
Fire hazard.
Maintain minimum 1/4" clearance between the
supply air duct and combustible materials in
the first 3' of ducting.
Failure to do so could result in fire causing
damage, injury or death.
Manual 2100-790
Page
14 of 49
Free Blow Applications
Some installations may not require extensive supply
duct work throughout the structure and are referred
to as free blow applications. A short field-fabricated
supply duct must be used in the wall cavity to
transition between the supply collar on the unit and
the supply louver grille in the room. The duct must
be properly insulated in order to conserve energy,
reduce heat conductivity and prevent condensation or
moisture damage. All joints must be taped or sealed to
prevent air or moisture entering the wall cavity. Follow
all clearances including distances to combustible
materials and all instructions provided in this manual.
A non-restrictive metallic supply air grille with
deflectors is required for free blow applications. Contact
the local Bard distributor or visit www.bardhvac.com for
ordering information.
A metallic return air grille is required for non-ducted
applications. The spacing between louvers on the grille
shall not be larger than 5/8". It is recommended that a
Bard Return Air Grille Kit be installed that is designed
specifically for the wall mount product. Contact the
local Bard distributor or visit www.bardhvac.com for
ordering information. A field-supplied return grille
that meets the 5/8" louver criteria and does not cause
the unit to exceed the maximum specified external
static pressure (ESP) may be used. If using a return
air filter grille, filters must be of sufficient size to
allow a maximum velocity of 400 fpm. Filter return
air grilles do not filter air being brought into the
structure through ventilation options including fresh air
dampers, ventilators, economizers and energy recovery
ventilators. Be sure to install the return grille with the
louvers pointed downward towards the floor. This will
help ensure return air is drawn upward from the floor
and improve air circulation in the room.
NOTE: If no return air duct is used, applicable
installation codes may limit this cabinet to
installation only in a single story structure.
Thermostat or Indoor Temperature Sensor Placement
The location and installation of the thermostat or
temperature sensor that monitors indoor temperature is
very important regarding unit operation. Avoid placing
the thermostat in an area exposed to direct sunlight
or air from doorways leading outdoors. Use a piece
of insulating material to close off conduit openings
or holes in the wall surface for wire entry into the
thermostat or temperature sensor. This will help avoid
non-conditioned air from entering the thermostat
and effecting temperature and/or humidity readings.
As common practice, the thermostat or temperature
sensor should measure the temperature of the air
being returned to the unit, and not the conditioned
air being supplied by the unit. Placing the thermostat
or temperature sensor near a return air opening will
normally result in optimal unit performance.
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