Bryant 548J*D Series User manual

548J***D
SINGLE PACKAGE ROOFTOP
HEAT PUMP
SIZES 17 AND 24 with PURONR(R--410A) REFRIGERANT
Installation Instructions
548J units for installation in the United States contain use of Bryant's 2-speed indoor fan
control system. This complies with the U.S. Department of Energy (DOE) efficiency standard
of 2018.
548J units for installation outside the United States may or may not contain use of the
2-speed indoor fan control system as they are not required to comply with the U.S.
Department of Energy (DOE) efficiency standard of 2018.
For specific details on operation of the Bryant 2-speed indoor fan system refer to the
Variable Frequency Drive (VFD) Factory-Installed Option 2-Speed Motor Control Installation,
Setup and Troubleshooting manual.
NOTE: Read the entire instruction manual before starting
the installation.
TABLE OF CONTENTS
SAFETY CONSIDERATIONS 2....................
Rated Indoor Airflow (cfm) 3.....................
REFRIGERATION SYSTEM COMPONENTS 10......
INSTALLATION 12..............................
Jobsite Survey 12...............................
Step 1 -- Plan for Unit Location 12.................
Roof Mount 12...............................
Step 2 -- Plan for Sequence of Unit Installation 12.....
Curb--Mounted Installation 12...................
Pad--Mounted Installation 12....................
Frame--Mounted Installation 12..................
Step 3 -- Inspect Unit 12..........................
Step 4 -- Provide Unit Support 12..................
Roof Curb Mount 12...........................
Slab Mount (Horizontal Units Only) 15............
Alternate Unit Support
(In Lieu of Curb or Slab Mount) 15...............
Step 5 -- Field Fabricate Ductwork 15...............
Step 6 -- Rig and Place Unit 15....................
Positioning on Curb 16.........................
Step 7 -- Horizontal Duct Connection 16.............
Step 8 -- Install Outside Air Hood -- Factory Option 16...
Step 9 -- Install External Condensate Trap and Line 17.
Step 10 -- Make Electrical Connections 18...........
Field Power Supply 18.........................
Units Without Factory--Installed
Non--Fused Disconnect 18......................
Units With Factory--Installed
Non--Fused Disconnect 18......................
All Units 21..................................
Convenience Outlets 22........................
Factory--Option Thru--Base Connections 23.........
Units Without Thru--Base Connections 23..........
Field Control Wiring 23........................
Thermostat 23................................
Central Terminal Board 24.......................
Commercial Defrost Board 24.....................
Units Without Thru--Base Connection Kit 26........
Heat Anticipator Settings 26.....................
Transformer Connection for 208--v Power Supply 26.
Electric Heaters 27..............................
Low--Voltage Control Connections 27.............
EconoMi$erRX (Factory--Installed Option) 28.......
Product Description 28.........................
System Components 28.........................
Specifications 28...............................
W7220 Economizer Module 28..................
Electrical 28.................................
Inputs 28....................................
Outputs 29...................................
Environmental 29.............................
Economizer Module Wiring Details 29............
S--Bus Sensor Wiring 29........................
CO2Sensor Wiring 30.........................
Interface Overview 30..........................
User Interface 30..............................
Keypad 30...................................
Menu Structure 31..............................

2
Setup and Configuration 31.......................
Time--out and Screensaver 31....................
Sequence of Operation 37........................
Enthalpy Settings 40............................
Two--Speed Fan Operation 40.....................
Checkout 41...................................
Power Up 41.................................
Initial Menu Display 41........................
Power Loss (Outage or Brownout) 42.............
Status 42....................................
Checkout Tests 42.............................
Troubleshooting 42.............................
Alarms 42...................................
Clearing Alarms 42............................
RTU Open Control System 43.....................
Supply Air Temperature (SAT) Sensor 45..........
Outdoor Air Temperature (OAT) Sensor 45.........
EconoMi$erR246............................
Field Connections 46............................
Space Temperature (SPT) Sensors 46..............
Indoor Air Quality (CO2)Sensor 47...............
Outdoor Air Quality Sensor 48...................
Smoke Detector/Fire Shutdown (FDS) 48..........
Space Relative Humidity Sensor or Humidistat 48...
Connecting Discrete Inputs 49...................
Communication Wiring -- Protocols 49..............
General 49...................................
Local Access 50..............................
RTU Open Troubleshooting 50...................
Outdoor Air Enthalpy Control 51..................
Differential Enthalpy Control 52.................
Smoke Detectors 52.............................
Return Air Sensor Tube Installation 52............
Smoke Detector Test Magnet 53..................
Additional Application Data 53..................
Step 11 -- Adjust Factory--Installed Options 53........
Step 12 -- Install Accessories 53...................
Step 13 -- Check Belt Tension 53...................
START--UP CHECKLIST 55.......................
SAFETY CONSIDERATIONS
Improper installation, adjustment, alteration, service,
maintenance, or use can cause explosion, fire, electrical
shock or other conditions which may cause personal injury
or property damage. Consult a qualified installer, service
agency, or your distributor or branch for information or
assistance. The qualified installer or agency must use
factory--authorized kits or accessories when modifying this
product. Refer to the individual instructions packaged with
the kits or accessories when installing.
Follow all safety codes. Wear safety glasses and work
gloves. Use quenching cloths for brazing operations and
have a fire extinguisher available. Read these instructions
thoroughly and follow all warnings or cautions attached to
the unit. Consult local building codes and appropriate
national electrical codes (in USA, ANSI/NFPA70,
National Electrical Code (NEC); in Canada, CSA C22.1)
for special requirements.
It is important to recognize safety information. This is the
safety--alert symbol . When you see this symbol on the
unit and in instructions or manuals, be alert to the
potential for personal injury.
Understand the signal words DANGER, WARNING,
CAUTION, and NOTE. These words are used with the
safety--alert symbol. DANGER identifies the most serious
hazards which will result in severe personal injury or
death. WARNING signifies hazards which could result in
personal injury or death. CAUTION is used to identify
unsafe practices, which may result in minor personal
injury or product and property damage. NOTE is used to
highlight suggestions which will result in enhanced
installation, reliability, or operation.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could cause personal
injury or death.
Before performing service or maintenance operations
on unit, always turn off main power switch to unit and
install lockout tag. Unit may have more than one
power switch.
!WARNING
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this warning could cause personal
injury, death and/or equipment damage.
Puronr(R--410A) refrigerant systems operate at
higher pressures than standard R--22 systems. Do not
use R--22 service equipment or components on Puron
refrigerant equipment.
!WARNING
PERSONAL INJURY AND ENVIRONMENTAL
HAZARD
Failure to follow this warning could cause personal
injury or death.
Relieve pressure and recover all refrigerant before
system repair or final unit disposal.
Wear safety glasses and gloves when handling
refrigerants. Keep torches and other ignition sources
away from refrigerants and oils.
!WARNING

3
CUT HAZARD
Failure to follow this caution may result in personal
injury.
Sheet metal parts may have sharp edges or burrs. Use
care and wear appropriate protective clothing, safety
glasses and gloves when handling parts and servicing
air conditioning equipment.
CAUTION
!Rated Indoor Airflow (cfm)
The table to the right lists the rated indoor airflow used
for the AHRI efficiency rating for the units covered in this
document.
Model Number
Full Load Airflow (cfm)
Vertical Airflow Units Horizontal Airflow Units
548J*17 5250 5250
548J*24 6500 6000
Model
J - Puron®(R-410A) Refrigerant
Unit Type
548 -Packaged Heat Pump
with optional Electric Heat
Packaging, Controls and
2-Speed Indoor Fan Motor
A = Standard packaging, electro-mechanical
controls that require W7212
EconoMi$er IV
C = Standard packaging, electro-mechanical
controls that require W7212
EconoMi$er X
D = Standard packaging and 2-speed indoor
fan motor (VFD) controller
Cooling Tons (Vertical Air Flow Models Only)
17 = 15 tons
24 = 20 tons
Heat Level
(Field installed electric heaters available)
000 = No Heat
Indoor Fan Options
1 = Standard Static/Vertical Supply, Return Air Flow
2 = Medium Static/Vertical Supply, Return Air Flow
3 = High Static/Vertical Supply, Return Air Flow
B =
Medium Static, High Efficiency Motor/Vertical Supply,
Return Air Flow
C = High Static, High Efficiency Motor/Vertical Supply,
Return Air Flow
5 = Standard Static/Horizontal Supply, Return Air Flow
(except 24 size)
6 = Medium Static/Horizontal Supply, Return Air Flow
7 = High Static/Horizontal Supply, Return Air Flow
F =
Medium Static, High Efficiency Motor/ Horizontal Supply,
Return Air Flow
G = High Static, High Efficiency Motor/Horizontal Supply,
Return Air Flow
Refrig. System Options
D = Two stage Cooling
Coil Options (Outdoor - Indoor - Hail Guard)
A = Al/Cu - Al/Cu
B = Precoat Al/Cu - Al/Cu
C = E-coat Al/Cu - Al/Cu
D = E-coat Al/Cu - E-coat Al/Cu
E = Cu/Cu - Al/Cu
F = Cu/Cu - Cu/Cu
M = Al/Cu - Al/Cu — Louvered Hail Guards
N = Precoat Al/Cu - Al/Cu — Louvered Hail Guards
P = E-coat Al/Cu - Al/Cu — Louvered Hail Guards
Q = E-coat Al/Cu - E-coat Al/Cu — Louvered Hail Guards
R = Cu/Cu - Al/Cu — Louvered Hail Guards
S = Cu/Cu - Cu/Cu — Louvered Hail Guards
Voltage
E = 460-3-60
P = 208/230-3-60
T = 575-3-60
Outdoor Air Options
A = None
B = Temperature Economizer w/ Barometric Relief,
Standard Leak (W7212 or W7220)
D = Temperature Economizer w/ centrifugal power
exhaust, Standard Leak (W7212 or W7220)
E =
Temperature Economizer w/ Barometric Relief ,
Standard Leak w/
CO
2
(W7212 or W7220)
G = Temperature Economizer w/ centrifugal power
exhaust, Standard Leak w/
CO
2
(W7212 or W7220)
H =
Enthalpy Economizer w/ Barometric Relief,
Standard Leak (W7212 or W7220)
K =
Enthalpy Economizer w/ centrifugal power exhaust,
Standard Leak (W7212 or W7220)
L =
Enthalpy Economizer w/ Barometric Relief,
Standard Leak w/
CO
2
(W7212 or W7220)
N =
Enthalpy Economizer w/ centrifugal power exhaust,
Standard Leak (W7212 or W7220)
P = Manual Outdoor Air Damper
Q = Motorized 2 Position Damper
U = Temperature Economizer w/ Barometric Relief,
Ultra Low Leak (W7220)
V = Temperature Economizer
w/ centrifugal power
exhaust, Ultra Low Leak (W7220)
W=
Enthalpy Economizer w/ Barometric Relief,
Ultra Low Leak (W7220)
X =
Enthalpy Economizer w/ centrifugal power exhaust,
Ultra Low Leak (W7220)
Example:
Position:
548JP17D000A1B0AA
123456789
10 11 12 13 14 15 16 17
Factory Installed Options
0A = None
NOTE: See the 548J 15 to 20 ton Price Pages for
a complete list of factory installed options.
a548J---014
Fig. 1 -- 548J 17--24 Model Number Nomenclature (Example)

4
a548J---015
Fig. 2 -- Unit Dimensional Drawing – Size 17 Units

5
a548J---016
Fig. 2 -- Unit Dimensional Drawing – Size 17 Units (cont)

6
a548J---017
Fig. 2 -- Unit Dimensional Drawing – Size 17 Units (cont)

7
a548J---018
Fig. 3 -- Unit Dimensional Drawing – Size 24 Units

8
a548J---019
Fig. 3 -- Unit Dimensional Drawing – Size 24 Units (cont)

9
a548J---020
Fig. 3 -- Unit Dimensional Drawing – Size 24 Units (cont)

10
C
B
D
A
C12392
LOCATION DIMENSION CONDITION
A36---in. (914 mm) • Recommended clearance for air flow and service
B42---in. (1067 mm) • Recommended clearance for air flow and service
C
18---in. (457 mm)
• No Convenience Outlet
•NoEconomizer
• No field installed disconnect on economizer hood side (Factory ---installed disconnect installed).
36---in. (914 mm) • Convenience Outlet installed.
• Vertical surface behind servicer is electrically non---conductive (e.g.: wood, fiberglass).
42---in. (1067 mm) • Convenience Outlet installed.
• Vertical surface behind servicer is electrically conductive (e.g.: metal, masonry).
96---in. (2438 mm) • Economizer and/or Power Exhaust installed.
• Check for sources of flue products with 10 feet (3 meters) of economizer fresh air intake.
D42---in. (1067 mm) • Recommended clearance for service.
NOTE: Unit not designed to have overhead obstruction. Contact Application Engineering for guidance on any application planning
overhead obstruction or for vertical clearances.
Fig. 4 -- Service Clearance Dimensional Drawing
REFRIGERATION SYSTEM
COMPONENTS
Each heat pump refrigeration system includes a
compressor, accumulator, reversing valve, dual--function
outdoor coil with vapor header check valve, cooling liquid
line with a filter drier and a check valve, dual--function
indoor coil with a vapor header check valve, and heating
liquid line with a check valve and a strainer. Size 14 units
have two compressor--circuits. See Fig. 5 for typical unit
piping schematic (4--row indoor coil with two
compressor--circuits is shown).
Dual--function outdoor and indoor coils are designed to
provide parallel coil circuits during evaporator--function
operation and converging coil circuits during the
condenser--function operation.
Reversing Valve and Check Valve Position
See Fig. 5 (on page 11) and Tables 1 -- 3.
Troubleshooting Refrigerant Pressure Problems and
Check Valves
Refer to Fig. 5 and the Cooling Mode and Heating Mode
tables (Tables 1 and 2).
Refrigerant System Pressure Access Ports
There are two access ports in each circuit -- on the suction
tube and the discharge tube near the compressor. These are
brass fittings with black plastic caps. The hose connection
fittings are standard 1/4--inch SAE male flare couplings.
The brass fittings are two--piece High Flow valves, with a
receptacle base brazed to the tubing and an integral
spring--closed check valve core screwed into the base. See
Fig. 6 on page 11. This check valve is permanently
assembled into this core body and cannot be serviced
separately. Replace the entire core body if necessary. Service
tools are available from Replacement Components that
allow the replacement of the check valve core without
having to recover the entire system refrigerant charge. Apply
compressor refrigerant oil to the check valve core’s bottom
O--ring. Install the fitting body and torque to 96 10 in--lbs
(10.9 1 Nm). Do not exceed 106 in--lbs (11.9 Nm) when
tightening.
Table 1 – Cooling Mode (each circuit)
Component Status/Position
Reversing Valve Energized
Check Valve A Closed
Check Valve B Open
Check Valve C Closed
Check Valve D Open

11
Table 2 – Heating Mode (each circuit)
Component Status/Position
Reversing Valve De--- energized
Check Valve A Open
Check Valve B Closed
Check Valve C Open
Check Valve D Closed
Table 3 – Defrost Mode
Component Status/Position
Defrost Thermostat Closed
Outdoor Fan(s) Off
Reversing Valve Energized
Check Valve A Closed
Check Valve B Open
Check Valve C Closed
Check Valve D Open
COMPRESSOR
ACCUMULATOR
HPS
COMPRESSOR
ACCUMULATOR
HPS
Filter
Drier 2B
1B
LPS/LOC
Acutrol DFT 1
Cooling Liquid Lines
DFT 2
2A
1A
1D
2D
Outdoor Coil
Indoor Coil
Comp 2
Comp 1
2C
1C Strainer
Heating Mode Liquid Lines
Acutrol
Reversing
Valve
Reversing
Valve
C160139
Fig. 5 -- Typical Unit Piping Schematic
5/8” HEX 0.47
30°
0.596
1/2-20 UNF RH
1/2” HEX
45°
WASHER
O-RING
7/16-20 UNF RH
DEPRESSOR PER AHRI 720
+.01/-.035
FROM FACE OF BODY
This surface provides a metal to metal seal when
torqued into the seat. Appropriate handling is
required to not scratch or dent the surface.
SEAT CORE
(Part No. EC39EZ067)
a548J---009
Fig. 6 -- CoreMax* Access Port Assembly
* CoreMax is a registered trademark of Fastest, Inc.

12
INSTALLATION
Jobsite Survey
Complete the following checks before installation.
1. Consult local building codes and the NEC (National
Electrical Code) ANSI/NFPA 70 for special installa-
tion requirements.
2. Determine unit location (from project plans) or select
unit location.
3. Check for possible overhead obstructions which may
interfere with unit lifting or rigging.
Step 1 — Plan for Unit Location
Select a location for the unit and its support system (curb
or other) that provides for the minimum clearances
required for safety. This includes the clearance to
combustible surfaces, unit performance and service access
below, around and above unit as specified in unit
drawings. See Fig. 4.
NOTE: Consider also the effect of adjacent units.
Unit may be installed directly on wood flooring or on Class
A, B, or C roof--covering material when roof curb is used.
Do not install unit in an indoor location. Do not locate air
inlets near exhaust vents or other sources of contaminated
air.
Although unit is weatherproof, avoid locations that permit
water from higher level runoff and overhangs to fall onto
the unit.
Select a unit mounting system that provides adequate
height to allow installation of condensate trap per
requirements.RefertoStep9—InstallExternal
Condensate Trap and Line – for required trap dimensions.
Roof Mount —
Check building codes for weight distribution
requirements. Unit operating weight is shown in Table 4.
Table 4 – Operating Weights
548J***D UNITS LB (KG)
17 24
Base Unit 1775 (807) 2100 (955)
Economizer 246 (112) 246 (112)
Powered Outlet 35 (16) 35 (16)
Curb
14--- in./356 mm 240 (109) 255 (116)
24--- in./610 mm 340 (154) 355 (161)
Step 2 — Plan for Sequence of Unit Installation
The support method used for this unit will dictate different
sequences for the steps of unit installation. For example,
on curb--mounted units, some accessories must be
installed on the unit before the unit is placed on the curb.
Review the following for recommended sequences for
installation steps.
Curb--Mounted Installation —
Install curb
Install field--fabricated ductwork inside curb
Install thru--base service connection fittings (affects
curb and unit)
Rig and place unit
Remove top skid
Install condensate line trap and piping
Make electrical connections
Install other accessories
Pad--Mounted Installation —
Prepare pad and unit supports
Rig and place unit
Remove duct covers and top skid
Install field--fabricated ductwork at unit duct openings
Install condensate line trap and piping
Make electrical connections
Install other accessories
Frame--Mounted Installation —
Frame--mounted applications generally follow the
sequence for a curb installation. Adapt as required to
suit specific installation plan.
Step 3 — Inspect unit
Inspect unit for transportation damage. File any claim
with transportation agency.
Confirm before installation of unit that voltage, amperage
and circuit protection requirements listed on unit data
plate agree with power supply provided.
Step 4 — Provide Unit Support
Roof Curb Mount —
Accessory roof curb details and dimensions are shown in
Fig. 7 (size 17 units) and Fig. 8 (size 24 units). Assemble
and install accessory roof curb in accordance with
instructions shipped with the curb.
NOTE: 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. 7 and Fig. 8. Improperly
applied gasket can also result in air leaks and poor unit
performance.
Curb should be level. This is necessary for unit drain to
function properly. Unit leveling tolerances are show in
Fig. 9 (on page 15). Refer to Accessory Roof Curb
Installation Instructions for additional information as
required.

13
C10139
Fig. 7 -- Roof Curb Details – Size 17 Units

14
C10140
Fig. 8 -- Roof Curb Details – Size 24 Units

15
A-B
0.5″ (13)
B-C
1.0″ (25)
A-C
1.0″ (25)
MAXIMUM ALLOWABLE
DIFFERENCE IN. (MM)
a50--- 9658
Fig. 9 -- Unit Leveling Tolerances
Install insulation, cant strips, roofing felt, and counter
flashing as shown. Ductwork must be attached to curb and
not to the unit. The accessory thru--the--base power
package must be installed before the unit is set on the roof
curb.
If electric and control wiring is to be routed through the
basepan remove knockouts in basepan located in control
box area, see Fig. 10 for location. Attach the service
connections to the basepan.
Control Box
A
ccess Panel
Filter and
Indoor Coil
Access Panel
Indoor Blower
Access Panel
Electric Heat
Access Panel Compressor
(each side)
C09118
Fig. 10 -- Typical Access Panel Locations
Slab Mount (Horizontal Units Only) —
Provide a level concrete slab that extends a minimum of
6–in. (150 mm) 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.
Alternate Unit Support
(InLieuofCurborSlabMount)—
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 4 equally
spaced 4--in. x 4--in. (102 mm x 102 mm) pads on each
side. Locate pads so that they support the rails. Make sure
to avoid the fork openings.
Step 5 — Field Fabricate Ductwork
Cabinet return-air static pressure (a negative condition)
shall not exceed 0.35 in. wg (87 Pa) with economizer or
0.45 in. wg (112 Pa) without economizer.
For vertical ducted applications, secure all ducts to roof curb
and building structure. Do not connect ductwork to unit.
Insulate and weatherproof all external ductwork, joints,
and roof openings with counter flashing and mastic in
accordance with applicable codes.
Ducts passing through unconditioned spaces 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.
For units with accessory electric heaters, minimum clearance
is not required around ductwork. One inch (25 mm)
clearance to combustible materials must be maintained for
the first 48 inches (1220 mm) of ductwork exiting the unit.
This applies to horizontal and vertical applications.
Outlet grilles must not lie directly below unit discharge.
NOTE: A 90--degree elbow must be provided in the
ductwork to comply with UL (Underwriters Laboratories)
code for use with electric heat.
PERSONAL INJURY HAZARD
Failure to follow this warning could cause personal
injury.
For vertical supply and return units, tools or parts
could drop into ductwork and cause an injury. Install
a 90--degree turn in the return ductwork between the
unit and the conditioned space. If a 90--degree elbow
cannot be installed, then a grille of sufficient strength
and density should be installed to prevent objects
from falling into the conditioned space. Due to
electric heater, supply duct will require 90--degree
elbow.
!WARNING
Step 6 — Rig and Place Unit
Keep unit upright and do not drop. Spreader bars are not
required 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 Table 4 (on page 12) and Fig. 11 for
additional information.
Lifting holes are provided in base rails as shown in Fig. 11.
Refer to rigging instructions on unit.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in
equipment damage.
All panels must be in place when rigging. Unit is not
designed for handling by fork truck.
CAUTION
!
Before setting the unit onto the curb, recheck gasketing on
curb.

16
"B"
"C"
"A"
"914-1371"
(36"-54")
DETAIL A
SEE DETAIL A
PLACE ALL SEAL STRIP
IN PLACE BEFORE PLACING
UNIT ON ROOF CURB.
DUCT END
C09107
UNIT MAX WEIGHT DIMENSIONS
A B C
LB KG IN. MM IN. MM IN. MM
548J*17 D 2070 940 127.8 3249 58.7 1491 52.3 1328
548J*24 D 2358 1071 141.5 3595 58.7 1491 52.3 1328
NOTES:
1. Dimensions in ( ) are in millimeters.
2. Hook rigging shackles through holes in base rail, as shown in detail “A.” Holes in base rails are centered around the unit center of
gravity. Use wooden top to prevent rigging straps from damaging unit.
Fig. 11 -- Rigging Details
PositioningonCurb—
Position unit on roof curb so that the following clearances
are maintained: 1/4in. (6 mm) clearance between the roof
curb and the base rail inside the right and left, 1/2in.
(12 mm) clearance between the roof curb and the base rail
inside the front and back. This will result in the distance
between the roof curb and the base rail inside on the
condenser end of the unit being approximately equal to
Detail A in Fig. 7 and 8.
Do not attempt to slide unit on curb after unit is set. Doing
so will result in damage to the roof curb seal.
Although unit is weatherproof, guard against water from
higher level runoff and overhangs.
After unit is in position, remove rigging skids and
shipping materials.
Step 7 — Horizontal Duct Connection
Refer to Fig. 2 and 3 for locations and sizes of the
horizontal duct connections. Note that there are two
different return air duct connection locations – one for
unit without an economizer (on back side of unit) and a
different one for unit equipped with an economizer (on
left end, under the economizer hood). The supply air duct
connection is on the back side. See Fig. 12 for top view
depicting typical horizontal duct arrangements.
Field--supplied (3/4--inch) flanges should be attached to
horizontal duct openings (see Fig. 12) and all ductwork
should be secured to the flanges. Insulate and
weatherproof all external ductwork, joints, and roof or
building openings with counter flashing and mastic in
accordance with applicable codes.
Return Air Duct
with Economizer
Return Air Duct
without
Economizer
Horizontal
Supply Air
C10740
UNIT
Supply Return without
Economizer
Return with
Economizer
Location Back Back Left end
548J*17 H e i g h t --- I n . (m m ) 157/8(402) 413/8(1051) 183/8(467)
W i d t h --- i n . ( m m ) 293/4(756) 233/8(593) 615/8(1564)
548J*24 H e i g h t --- I n . (m m ) 157/8(402) 493/8(1253) 183/8(467)
W i d t h --- i n . ( m m ) 293/4(756) 233/8(593) 615/8(1564)
Fig. 12 -- Horizontal Duct Opening Dimensions
Step 8 — Install Outside Air Hood —
Factory Option
The outside air hood for factory--option economizer and
two--position damper is shipped in knock--down form and
requires field assembly. The panel for the hood top is
shipped on the end of the unit (see Fig. 13). The
remaining parts for the hood assembly (including side
panels, filters and tracks) are shipped in a carton that is
secured to the rear of the blower assembly. Access the
carton location through rear panel (see Fig. 14).

17
Hood Top
Shipping
Position
C09134
Fig. 13 -- Hood Top – Shipping Position
Hood
Package
C13785
Fig. 14 -- Hood Package – Shipping Location
To remove the hood parts package:
1. Remove the back blower access panel.
2. Locate and cut the strap, being careful to not damage
any wiring.
3. Carefully lift the hood package carton through the
back blower access opening.
See Fig. 15 for identification of the various parts of the
hood assembly.
A
pply Seal Strips
to the back of
these flanges
Apply Seal Strip
to the front of
this flange
Apply Seal Strip
to the front of
this flange
Apply Seal Strip
to the back of
this flange
Seal Strips
Apply Seal Strips
to the back of
these surfaces
7
7
22
1
3
4
4
44
5
6
56
Item # Description Qty
1 Angles 4
2 Side Plates 2
3 Hood 1
4 Outdoor Air Screens 4
5 Side Filter Supports 2
6 Side Drip Angles 2
7 Top Diverters 2
C09079
Fig. 15 -- Hood Part Identification and Seal Strip
Application Areas
To assemble the outside air hood:
1. Remove hood top panel from shipping position on
unit end.
2. Install four angles to the upper end panel using the
screws provided
3. Apply seal strip to mating flanges on the side plates
of the hood (see Fig. 15).
4. Secure side plates to panel using the screws provided.
5. Apply seal strip to mating flange of the hood (see
Fig. 15).
6. Secure top flange using screws provided in kit.
7. Install outdoor air screens by sliding them into the
channel formed by the four angles installed in step 2.
Make sure that the screens extend across the entire
length of the hood.
8. Install side filter supports using the screws provided
9. Install side drip angles using the screws provided.
10. Run a continuous length of seal strip across the hood
covering the engagement holes in the lower hood.
11. Install top diverter using the screws provided.
12. On units with barometric relief, remove screws at bot-
tom of relief damper. Do not discard damper door.
C09090
Fig. 16 -- Hood Assembly – Completed
Step 9 — Install External Condensate Trap and
Line
The unit has one 3/4-in. condensate drain connection on
the end of the condensate pan (see Fig. 17) See Fig. 2 (or
Fig. 3), item “E”, in the view labeled “BACK” for the
location of the condensate drain connection.
STANDARD
SIDE DRAIN
C09056
Fig. 17 -- Condensate Drain Pan Connection
The piping for the condensate drain and external trap can
be completed after the unit is in place. Hand tighten
fittings to the drain pan fitting. Provide adequate support
for the drain line. Failure to do so can result in damage to
the drain pan. See Fig. 18.

18
NOTE: Trap should be deep enough to offset maximum unit static
difference. A 4 in. (102 mm) trap is recommended.
MINIMUM PITCH
1” (25mm) PER
10’ (3m) OF LINE
BASE RAIL
OPEN
VENT
TO ROOF
DRAIN
DRAIN PLUG
ROOF
CURB
SEE NOTE
3˝(76mm)
MIN
a50--- 9660
Fig. 18 -- Condensate Drain Piping Details
All units must have an external trap for condensate
drainage. Install a trap at least 4-in. (102 mm) 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 (25 mm in 3 m) of run. Do
not use a pipe size smaller than the unit connection
(3/4-in.).
Step 10 — Make Electrical Connections
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury or death.
Do not use gas piping as an electrical ground. Unit
cabinet must have an uninterrupted, unbroken
electrical ground to minimize the possibility of
personal injury if an electrical fault should occur. This
ground may consist of electrical wire connected to
unit ground lug in control compartment, or conduit
approved for electrical ground when installed in
accordance with NEC (National Electrical Code);
ANSI/NFPA 70, latest edition (in Canada, Canadian
Electrical Code CSA [Canadian Standards
Association] C22.1), and local electrical codes.
!WARNING
NOTE: Check all factory and field electrical connections
for tightness. Field--supplied wiring shall conform with
the limitations of 63_F(33_C) rise.
Field Power Supply —
If equipped with optional Powered Convenience Outlet:
The power source leads to the convenience outlet’s
transformer primary are not factory connected. Installer
must connect these leads according to required operation
of the convenience outlet. If an always--energized
convenience outlet operation is desired, connect the
source leads to the line side of the unit--mounted
disconnect. (Check with local codes to ensure this method
is acceptable in your area.) If a de--energize via unit
disconnect switch operation of the convenience outlet is
desired, connect the source leads to the load side of the
unit disconnect. On a unit without a unit--mounted
disconnect, connect the source leads to the terminal block
with unit field power leads.
Field power wires are connected to the unit at line--side
pressure lugs on the terminal block (see wiring diagram
label for control box component arrangement) or at
factory--installed option non--fused disconnect switch. Use
copper conductors only.
NOTE: Make field power connections directly to line
connection pressure lugs only.
!WARNING
FIRE HAZARD
Failure to follow this warning could result in
intermittent operation or performance satisfaction.
Do not connect aluminum wire between disconnect
switch and furnace. Use only copper wire.
(See Fig. 19.)
COPPER
WIRE ONLY
ELECTRIC
DISCONNECT
SWITCH
ALUMINUM
WIRE
A93033
Fig. 19 -- Disconnect Switch and Unit
Units Without Factory--Installed
Non--Fused Disconnect —
When installing units, provide a disconnect switch per
NEC (National Electrical Code) of adequate size.
Disconnect sizing data is provided on the unit informative
plate. Locate on unit cabinet or within sight of the unit per
national or local codes. Do not cover unit informative
plate if mounting the disconnect on the unit cabinet.
Units With Factory--Installed
Non--Fused Disconnect —
The factory--installed option non--fused disconnect switch
(NFD) is located in the main control box. The manual
switch handle and shaft are shipped in the control box and
must be mounted on the corner post adjacent to the
control box (see Fig. 22). Note that the tape covering the
hole for the shaft in the corner post must be removed prior
to handle and shaft installation.

19
a50--- 9696
Fig. 20 -- 548J 17--24 Control Wiring Diagram with VFD Option

20
a50--- 9697
Fig. 21 -- Typical 548J 17--24 Power Wiring Diagram (208/230V 3 Phase 60Hz unit shown)