Carrier 50LJ - Manual (Page 2)

CONTENTS
Page
SAFETY CONSIDERATIONS .............................. 1
INSTALLATION ................................................... 2-21
Rigging and Unit Placement ................................ 2
Roof Curb ............................................................... 2
Roof Mount ............................................................ 2
Slab Mount ............................................................ 2
Alternate Unit Support Methods ......................... 2
Positioning ............................................................ 2
Field-Fabricated Ductwork .................................. 3
Condensate Drain ...............................................
8
Outdoor-Air Inlet Adjustments ..........................
8
Install Outdoor-Air Hoods .................................. 12
Field Wiring Routing ........................................... 14
Field Electrical Connections ............................. 15
Gas Piping ........................................................... 21
Installing Flue/lnlet Hoods ................................. 21
START-UP ........................................................ 21-24
Unit Preparation .................................................. 21
Internal Wiring ..................................................... 21
Refrigerant Service Ports .................................. 21
Crankcase Heaters ............................................. 21
Compressor Oil ................................................... 21
Unit Voltage ......................................................... 21
Leak Test and Dehydration ............................... 21
Evaporator Fan, Belt and Sheaves ................... 22
Condenser Fans and Motors ............................. 22
Page
Return-Air Filters ................................................ 22
Economizer Inlet Screens .................................. 22
Economizer Dampers and Potentiometer
Settings .............................................................. 22
Operating Sequences ......................................... 23
Ventilation Air Circulation
(Continuous Fan) .............................................. 24
Automatic Changeover Using Automatic
Changeover Thermostat ................................... 24
Head Pressure Control ....................................... 24
SERVICE .......................................................... 24-37
Service Access .................................................... 24
Cleaning ............................................................... 26
Lubrication ........................................................... 26
Adjustments ........................................................ 26
Refrigerant Feed Components .......................... 29
Acutrol™ Refrigerant Metering Device ............. 29
Filter Drier ............................................................ 29
Protective Devices .............................................. 29
Relief Devices ...................................................... 30
Control Circuit, 115-V ....................................... 30
Control Circuit, 24-V ......................................... 30
Gas Heat ............................................................... 30
Electric Heat ....................................................... 32
Control Board Checkout ................................... 32
INSTALLATION
This book contains instructions for 48/50LJ vertical supply/
return units and 50LW horizontal supply/retum units.
IMPORTANT: These units are not designed for han­
dling by forklift trucks.
Rigging and Unit Placement — Inspect unit for trans­
portation damage. File claim with transportation agency.
Do not drop unit; keep upright. Use spreader bars over unit
to prevent sling or cable damage. Rollers may be used to
move unit across a roof. Level by using unit frame as ref­
erence. See Fig. 1 for additional information. Unit physical
data is shown in Tables la and lb.
Roof Curb — Assemble and install as described in
instructions shipped with this accessory. Accessory roof curb
and information required to field fabricate a roof curb is
shown in Fig. 2a and 2b. Install insulation cant strips, roof­
ing and counter flashing as required. For unit drains to func­
tion properly, curb must be level or within tolerances shown
in Fig. 3.
Roof Mount — Check building codes for weight distri­
bution requirements. Unit weight is shown in Tables la and
lb.
Slab Mount — Provide a level concrete slab that ex­
tends beyond unit cabinet at least 6 Inches. Make a slab
8-in. thick with 4 in. above grade. (For condensate drain to
function properly, slab must be at least 4 in. above grade.
See Fig. 4.) Use gravel apron in front of condenser air inlet
to prevent grass and foliage from obstructing airflow.
Alternate Unit Support Methods Where the pre­
ferred curb or slab mount cannot be used, support unit with
sleepers on perimeter, using curb support area. However, if
sleepers cannot be used, support long sides of unit (see
Fig. 5a — 5c) with three 4-in. x 4-in. pads equally spaced.
Unit may sag if supported by comers only.
Positioning — Provide clearance around and above unit
for airflow, safety, and service access. Allow 12 ft above
the unit, and at least 4 ft on all sides for rated performance
and code compliance. If unit has economizer, allow 6 ft
clearance on that side. For preferred service access, allow
6 ft clearance on all sides.
Do not install unit in an indoor location. Do not locate
air inlets near exhaust vents or other sources of contami­
nated air.
Although unit is weatherproof, guard against water from
higher level runoff and overhangs.
IMPORTANT: Always line up the condenser end of
the unit tight against the roof curb.