Carrier 48LJD - Manual

HEATING & COOLING
48LJE/LJF004
48L J D/L J E/L J F005-007
Single-Package Rooftop Heating/Cooling Units
i
Installation, Start-Up, and Service Instructions
CONTENTS
SAFETY CONSIDERATIONS ...
Page
19
1
INSTALLATION .......................................................1
Step 1 — Provide Unit Support................................
• ROOF CURB
• SLAB MOUNT
Step 2 — Field Fabricate Ductwork .........................
Step 3 — Install External Trap for
Condensate Drain ..................................................
Step 4 — Rig and Place Unit ....................................
• POSITIONING
Step 5 — Install Flue Hood........................................
Step 6 — Install Gas Piping .....................................
Step 7 — Make Electrical Connections...................
• FIELD POWER SUPPLY
• FIELD CONTROL WIRING
• HEAT ANTICIPATOR SETTINGS
Step 8 - Make Outdoor-Air Adjustments and
Install Outdoor-Air Hood....................................... 10
• MANUAL OUTDOOR-AIR DAMPER
• TWO-POSITION DAMPER
• OPTIONAL ECONOMIZER
Step 9 — Adjust Evaporator-Fan Speed..................13
• DIRECT DRIVE MOTORS
• BELT DRIVE MOTORS
START-UP................
SERVICE ..................
TROUBLESHOOTING 20,21
21-25
26-31
SAFETY CONSIDERATIONS
Installation and servicing of air-conditioning equipment
can be hazardous due to system pressure and electrical com­
ponents. 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, ob­
serve precautions in the literature, tags and labels attached
to the unit, and other safety precautions that apply.
Follow all safety codes. Wear safety glasses and work
gloves. Use quenching cloth for unbrazing operations. Have
fire extinguishers available for all brazing operations.
A WARNING
Disconnect gas piping from unit when leak
testing at pressure greater than V2 psig. Pres­
sures greater than ’/2 psig will cause gas valve
damage resulting in hazardous condition. If
gas valve is subjected to pressure greater than
■ /2 psig, it must be replaced before use. When
pressure testing field-supplied gas piping at
pressures of V2 psig or less, a unit connected
to such piping must be isolated by manually
closing the gas valve(s).
A WARNING
Before performing service or maintenance operations
on unit, turn off main power switch to unit. Electrical
shock could cause personal injury.
INSTALLATION
Unit is shipped in the vertical discharge configuration.
To convert to horizontal configuration, remove screws from
side duct opening covers and remove covers. Using the same
screws, install covers on vertical duct openings with the
insulation-side down. Seals around duct openings must be
tight. See Fig. 1.
IMPORTANT: An external filter kit MUST be used
or the filters MUST be field-installed outside the unit
on horizontal discharge applications with optional econ­
omizer. Otherwise, the economizer must be partially
removed to access the filters. The area of the field-
installed filters should be equal to the area of the factory-
installed filters.
Step 1 — Provide Unit Support
ROOF CURB — Assemble and install accessory roof curb
in accordance with instructions shipped with curb. See
Fig. 2. Install insulation, cant strips, roofing felt, and counter
flashing as shown. Ductwork must be attached to curb, not
to the unit. If gas, electric power, or control power is to be
routed through the curb, attach the accessory thm-the-curb
service connection plates to the roof curb in accordance with
the accessory installation instmctions. Connection plates must
be installed before unit can be set on roof curb.
IMPORTANT: The gasketing of the unit to the roof
curb is critical for a watertight seal. Install gasket sup­
plied with the roof curb as shown in Fig. 2. Improp­
erly applied gasket can result in air leaks and poor
unit performance.
Curb should be level. Unit leveling tolerances are shown
in Fig. 3. This is necessary for unit drain to function prop­
erly. Refer to Accessory Roof Curb Installation Instruc­
tions 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 — Secure all
ducts to roof curb and building structure on vertical units.
Do not connect ductwork to unit. For horizontal applica­
tions, field-supplied flanges should be attached to horizon­
tal discharge openings and all ductwork should be secured
to the flanges. Insulate and weatherproof all external duct­
work, joints, and roof openings with counter flashing and-
mastic in accordance with applicable codes.
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obiigations.
Book|1 |4 PC 111 Catalog No. 564-987 Printed in U S A Form 48LJ-7SI Pg 1 4-93 Replaces: 48LJ-5SI
Tab la 6a