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Cancels: II 551B-90-6 II 551B-90-7
10/15/05
CONTENTS
Page
SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . 1
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-37
I. Step 1 — Provide Unit Support. . . . . . . . . . . . . . . . . 1
II. Step 2 — Field Fabricate Ductwork . . . . . . . . . . . . . 1
III. Step 3 — Install Condensate Drain Line
and External Trap. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
IV. Step 4 — Rig and Place Unit. . . . . . . . . . . . . . . . . . . 2
V. Step 5 — Make Electrical Connections . . . . . . . . . . 7
VI. Step 6 — Adjust Factory-Installed Options. . . . . . 11
VII. Step 7 — Adjust Evaporator-Fan Speed . . . . . . . . 21
PRE-START-UP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
START-UP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38-41
SERVICE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41-45
TROUBLESHOOTING. . . . . . . . . . . . . . . . . . . . . . . . . . . .46-49
INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
START-UP CHECKLIST . . . . . . . . . . . . . . . . . . . . . . . . . . CL-1
SAFETY CONSIDERATIONS
Installation and servicing of air-conditioning equipment can
be hazardous due to system pressure and electrical compo-
nents. Only trained and qualified service personnel should
install, repair, or service air-conditioning equipment.
Untrained personnel can perform basic maintenance func-
tions of cleaning coils and filters and replacing filters. All
other operations should be performed by trained service per-
sonnel. When working on air-conditioning equipment,
observe precautions in the literature, tags and labels
attached to the unit, and other safety precautions that may
apply.
Follow all safety codes. Wear safety glasses and work gloves.
Use quenching cloth for unbrazing operations. Have fire
extinguisher available for all brazing operations.
INSTALLATION
Unit is shipped in the vertical configuration. To convert to
horizontal configuration, remove side duct opening covers.
Using the same screws, install covers on vertical duct open-
ings with the insulation-side down. Seals around duct
openings must be tight. See Fig. 1.
I. STEP 1 — PROVIDE UNIT SUPPORT
A. Roof Curb
Assemble and install accessory roof curb in accordance with
instructions shipped with curb. Install insulation, cant
strips, roofing felt, and counter flashing as shown. Ductwork
must be attached to curb. If electric or control power is to be
routed through the basepan, attach the accessory thru-the-
bottom service connections to the basepan in accordance
with the accessory installation instructions. Connections
must be installed before unit is set on roof curb.
IMPORTANT: The gasketing of the unit to the roof curb is
critical for a watertight seal. Install gasket supplied with the
roof curb as shown in Fig. 2. Improperly applied gasket can
also result in air leaks and poor unit performance.
Curb should be level. This is necessary for unit drain to func-
tion properly. Unit leveling tolerances are shown in Fig. 3.
Refer to Accessory Roof Curb Installation Instructions for
additional information as required.
B. 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 con-
denser coil air inlet to prevent grass and foliage from
obstructing airflow.
NOTE: Horizontal units may be installed on a roof curb if
required.
C. Alternate Unit Support (Curb or Slab Mount)
A non-combustible sleeper rail can be used in the unit curb
support area. If sleeper rails cannot be used, support the
long sides of the unit with a minimum of 3 equally spaced
4-in. x 4-in. pads on each side.
II. STEP 2 — FIELD FABRICATE DUCTWORK
On vertical discharge units, secure all ducts to roof curb and
building structure. Do not connect ductwork to unit. For hori-
zontal applications, field-supplied flanges should be attached
to horizontal discharge openings and all ductwork attached
to the flanges. Insulate and weatherproof all external duct-
work, joints, and roof openings with counter flashing and
mastic in accordance with applicable codes.
Ducts passing through an unconditioned space must be insu-
lated 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 appli-
cable fire codes.
A minimum clearance to combustibles is not required around
ductwork on vertical discharge units. On horizontal dis-
charge units, a minimum clearance of 1 in. is required for the
first 12 in. of ductwork. Cabinet return-air static pressure (a
negative condition) should not exceed 0.30 in. wg with
EconoMi$er IV, or 0.45 in. wg without economizer.
CAUTION: Ensure voltage listed on unit data plate
agrees with electrical supply provided for unit.
WARNING: Before performing service or mainte-
nance operations on unit, turn off main power switch
to unit and install lockout tag. Electrical shock could
cause personal injury.
installation, start-up and
service instructions
SINGLE PACKAGE ROOFTOP
ELECTRIC COOLING UNITS
551B
Dura
Pac
Plus Series
Sizes 090-150
7
1
/
2
to 12
1
/
2
Tons