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Curb should be level. Unit leveling tolerances are shown in
Fig. 3. This is necessary for unit drain to function properly.
Refer to Accessory Roof Curb Installation Instructions for
additional information as required.
SLAB MOUNT (Horizontal Units Only) — Provide a level
concrete slab that extends a minimum of 6 in. beyond unit
cabinet. Install a gravel apron in front of condenser coil air inlet
to prevent grass and foliage from obstructing airflow.
NOTE: Horizontal units may be installed on a roof curb if
required.
Step 2 — Field Fabricate Ductwork —
ducts to roof curb and building structure on vertical ducted
units. Do not connect ductwork to unit. For horizontal applica-
tions, field-supplied flanges should be attached to horizontal
duct openings and all ductwork should be 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 applica-
ble fire codes.
A minimum clearance is not required around ductwork.
Cabinet return air static shall not exceed –.20 in. wg with
EconoMi$er2 or –.45 in. wg without economizer.
These units are designed for a minimum continuous heating
return-air temperature 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 tem-
peratures, 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 tem-
perature rise.
Step 3 — Install External Trap for Condensate
Drain —
3
The unit's
/
-in. condensate drain connections are
4
located on the bottom and side of the unit. Unit discharge con-
nections do not determine the use of drain connections; either
drain connection can be used with vertical or horizontal
applications.
Fig. 1 — Horizontal Conversion Panels
Secure all
2
When using the standard side drain connection, make sure
the plug (Red) in the alternate bottom connection is tight before
installing the unit.
To use the bottom drain connection for a roof curb installa-
tion, relocate the factory-installed plug (Red) from the bottom
connection to the side connection. The center drain plug looks
like a star connection, however it can be removed with a
socket drive extension. See Fig. 4. The piping for the conden-
sate drain and external trap can be completed after the unit is in
place.
All units must have an external trap for condensate drain-
age. Install a trap at least 4-in. deep and protect against freeze-
up. If drain line is installed downstream from the external trap,
pitch the line away from the unit at 1 in. per 10 ft of run. Do not
use a pipe size smaller than the unit connection (
Step 4 — Rig and Place Unit —
transportation damage. File any claim with transportation agen-
cy. Keep unit upright and do not drop. Spreader bars are not re-
quired if top crating is left on unit. Rollers may be used to move
unit across a roof. Level by using unit frame as a reference. See
Tables 1A and 1B and Fig. 5 for additional information.
Lifting holes are provided in base rails as shown in Fig. 6A
and 6B. Refer to rigging instructions on unit.
All panels must be in place when rigging.
POSITIONING — Maintain clearance around and above unit
to provide minimum distance from combustible materials,
proper airflow, and service access. See Fig. 6A and 6B. A prop-
erly positioned unit will have the following clearances between
1
unit and roof curb:
/
-in. clearance between roof curb and base
4
rails on each side and duct end of unit;
tween roof curb and condenser coil end of unit. (See Fig. 2,
section C-C.)
Do not install unit in an indoor location. Do not locate unit
air inlets near exhaust vents or other sources of contaminated
air.
Be sure that unit is installed such that snow will not block
the combustion intake or flue outlet.
1
/
-in.
2
3
/
in.).
4
Inspect unit for
1
/
-in. clearance be-
4
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