Step 3 -- Field Fabricate Ductwork
On vertical units, secure all ducts to roof curb and building
structure. Do not connect ductwork to unit. For horizontal
applications, field-supplied flanges should be attached to
horizontal discharge openings and all ductwork secured to the
flanges. Insulate and weatherproof all external ductwork, joints,
and roof openings with counter flashing and mastic in accordance
with applicable codes.
Ducts passing through an unconditioned space must be insulated
and covered with a vapor barrier.
If a plenum return is used on a vertical unit, the return should be
ducted through the roof deck to comply with applicable fire codes.
A minimum clearance is not required around ductwork. Cabinet
return-air static pressure (a negative condition) shall not exceed
0.35-in.wg with economizer or 0.45-in.wg without economizer.
These units are designed for a minimum continuous return air
temperature in heating of 50°F (dry bulb), or an intermittent
operation down to 45°F (dry bulb), such as when used with a night
set-back thermostat.
To operate at lower return-air temperatures, a field-supplied
outdoor-air temperature control must be used to initiate both stages
of heat when the temperature is below 45°F. Indoor comfort may
be compromised when these lower air temperatures are used with
insufficient heating temperature rise.
Step 4 -- Make Unit Duct Connections
Vertical Supply/Return Configuration
Unit is shipped in vertical supply/return configuration. Ductwork
openings are shown in Fig. 1 and 2. Attach the ductwork to the
roof curb. Do not attach duct directly to the unit.
PERSONAL INJURY HAZARD
Failure to follow this caution may result in personal injury.
For vertical supply and return units, tools or parts could
drop into ductwork and cause an injury. Install a 90 ° turn
in the return ductwork between the unit and the conditioned
space. If a 90 ° elbow cannot be installed, then a grille of
sufficient strength and density should be installed to prevent
objects from falling into the conditioned space.
Horizontal Supply/Return Applications
Unit can be field-converted from vertical supply/return to
horizontal supply/return. Remove all screws securing horizontal
duct covers to duct panel. Save panels. Install duct covers in the
vertical duct openings in the basepan with the insulation side up.
Covers will drop into openings and can be secured using
field-supplied self-tapping screws. Ductwork can be attached to
duct flanges provided on unit. When securing ductwork to unit, do
not drill in area below bead or above top edge of duct opening.
Step 5 -- Install Flue Hood and Inlet Hood
Flue hood (smaller hood), inlet hood (larger hood), and screens are
shipped inside the unit in the gas section. To install, open the heat
section door. The flue hood is attached to the heat section panel
from the outside using the screws provided. (See Fig. 4 and 5.)
_ INLET
HOOD
GAS SECTION FLUE
ACCESS DOOR HOOD
Fig. 4 - Flue and Inlet Hood
C06257
The inlet hood is installed by inserting the hood through the back
of the heat panel. Attach the hood by inserting the screws provided
through the clearance holes in the heat panel and into the intake
hood.
NOTE: When properly installed, the flue hood will line up with
the combustion fan housing. (See Fig. 6.)
g
ELECTRICAL
OPTION_NEL
CONTROLEOX
AND
COMPRESSOR
\,
'\
\
iNDOOR MOTOR
J ACCESSDOOR
SCREEN
(H_DDEN)
\\
CONDENSER COIL
ACCESS PANEL
BASEPAN CONNECTIONS
ACCESS PANEL
Fig. 5 - Panel and Filter Locations
C06255
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