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Rigging
CIRCULATING
AIR
AND
FILTERS
AIRFLOW CONVERSION
Units can easily be converted from horizontal to down-discharge
airflow delivery.
In down_lischarge
or high static installations, the
installer should measure the total external static and review the
blower performance
charts before performing the installation.
In
some installations it will be necessary to change the blower speed
to provide proper air flow.
Horizontal Air Flow
Remove supply and return duct covers which are attached to the
unit as shown below.
lemove
_ese
covers
for horizontal
duct
applications
Remove these panels
for downflowduct
applications
Duct Cover Installation
Down Discharae Aoolications
Cut insulation around bottom openings and remove panels from
the bottom of the unit, saving the screws holding the panels in
place.
DUCTWORK
Duct systems
and register sizes must be properly designed
for
the C.EM. and external static pressure rating of the unit. Duct work
should be designed in accordance with the recommended methods
of Air Conditioning
Contractors
of America Manual D (Residential)
or Manual Q (Commercial).
All ductwork exposed to the outdoors
must include a weatherproof barrier and adequate insulation.
A duct system should be installed in accordance with Standards of
the National Board of Fire Underwriters
for the Installation of Air
Conditioning, Warm Air Heating and Ventilating Systems. Pamphlets
No. 90A and 90B.
The supply duct from the unit through a wall may be installed with-
out clearance. However, minimum unit clearances as shown in the
appendix must be maintained.
The supply duct should be provided
with an access panel large enough to inspect the air chamber down-
stream of the heat exchanger.
A cover should be tightly attached to
prevent air leaks.
For duct flange dimensions on the unit refer to the Unit Dimension
illustration in the appendix.
For down-discharge
applications, the ductwork should be attached
to the roof curb prior to installing the unit. Duct work dimensions are
shown in the roof curb installation manual.
If desired, supply and return duct connections to the unit may be
made with flexible connections
to reduce possible unit operating
sound transmission.
FILTERS
CAUTION
To
PREVENT
PROPERTY
DAMAGE
DUE TO FIRE AND LOSS OF
EQUIPMENT
EFFICIENCY
OR EQUIPMENT
DAMAGE DUETODUSTANDLINT
BUILD UP ON INTERNAL
PARTS, NEVER
OPERATE
UNIT WITHOUT
AN AIR
FILTER INSTALLED
IN THE RETURN AIR SYSTEM.
Filters are not provided with unit and must be supplied and exter-
nally installed in the return duct system by the installer. A field-
installed tilter grille is recommended for easy and convenient ac-
cess to the tilters for periodic inspection and cleaning. When in-
stalling filters, ensure the air flow arrows on the tilter are pointing
toward the circulator blower.
Refer to the unit tilter size chart below for tilter size information.
MINIMUM
FILTER SIZE
NOMINAL SIZE (INCHES)
NOMINAL AREA
(SQ. FT.)
10x20
1.4
14x20
1.9
14x25
2.4
15x20
2.1
16x20
2.2
16x25
2.8
20x20
2.8
20x25
3.5
25x25
4.3
NOTE: Filters must have adequate face area for the rated quantity
of the unit. See the air delivery table below for recommended tilter
size. Size the filters in accordance with their manufacturer recom-
mendations. Throwaway tilters must be sized for a maximum face
velocity of 300 feet per minute.
6
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