Carrier 48SD User manual

1
48SD
Single--Packaged Gas Furnace/Air Conditioner
System with R--22 Refrigerant
Single-- And Three--Phase Units Sizes 018--060
Installation Instructions
NOTE: Read the entire instruction manual before starting the
installation.
NOTE: Installer: Make sure the Owner’s Manual and Service
Instructions are left with the unit after installation.
TABLE OF CONTENTS
Page
SAFETY CONSIDERATIONS 1........................
INTRODUCTION 2..................................
RECEIVING AND INSTALLATION 2--12................
Check Equipment 2.................................
Identify Unit 2...................................
Inspect Shipment 2................................
Provide Unit Support 2..............................
Roof Curb 2.....................................
Slab Mount 2....................................
Ground Mount 2.................................
Field Fabricate Ductwork 2...........................
Provide Clearances 6................................
Rig and Place Unit 6................................
Inspection 6.....................................
Use of Rigging Bracket 6...........................
Connect Condensate Drain 8..........................
Install Flue Hood 8..................................
Install Gas Piping 9.................................
Install Duct Connections 9............................
Configuring Units for Downflow (Vertical)
Discharge 9.....................................
Install Electrical Connections 11.......................
High--Voltage Connections 11.......................
Special Procedures for 208--V Operation 11.............
Control Voltage Connections 11......................
Heat Anticipator Setting 12.........................
Transformer Protection 12..........................
PRE--START--UP 12..................................
START--UP AND TROUBLESHOOTING 12--19...........
Check for Refrigerant Leaks 12........................
Start--Up Heating & Make Adjustments 13...............
Check Heating Control 13..........................
Check Gas Input 13...............................
Adjust Gas Input 13...............................
Check Burner Flame 14............................
Airflow and Temperature Rise 14.....................
Heating Sequence of Operation 14....................
Limit Switches 18................................
Rollout Switch 18................................
Start--Up Cooling & Make Adjustments 18...............
Checking Cooling Control Operation 18...............
Checking & Adjusting Refrigerant Charge 18...........
Indoor Airflow and Airflow Adjustments 19............
Cooling Sequence of Operation 19....................
MAINTENANCE 23--25...............................
Air Filter 23.......................................
Indoor Blower and Motor 23..........................
Flue Gas Passageways 23.............................
Induced Draft (Combustion Air) Blower 24...............
A99338
Fig. 1 -- Unit 48SD
(Low NOx Model Available)
Limit Switch 24....................................
Burner Ignition 24..................................
Main Burners 24...................................
Outdoor Coil, Indoor Coil, & Condensate Drain Pan 24.....
Outdoor Fan 25....................................
Electrical Controls and Wiring 25......................
Refrigerant Circuit 25................................
Indoor Airflow 25..................................
Metering Devices--
Thermostatic Expansion Valve 25....................
AccuRatertPiston 25.............................
Liquid Line Strainer 25..............................
TROUBLESHOOTING 25--27..........................
START--UP CHECKLIST 25...........................
SAFETY CONSIDERATIONS
Installation and servicing of this equipment can be hazardous due to
mechanical and electrical components. Only trained and qualified
personnel should install, repair, or service this equipment.
Untrained personnel can perform basic maintenance functions such
as cleaning and replacing air filters. All other operations must be
performed by trained service personnel. When working on this
equipment, observe precautions in the literature, on tags, and on
labels attached to or shipped with the unit and other safety
precautions that may apply.
Follow all safety codes. Installation must be in compliance with
local and national building codes. Wear safety glasses, protective
clothing, and work gloves. Have fire extinguisher available. Read
these instructions thoroughly and follow all warnings or cautions
included in literature and attached to the unit.
Recognize safety information. This is the safety--alert symbol .
When you see thissymbol on theunit and in instructions ormanuals,

2
be alert to the potential for personal injury. Understand these signal
words: DANGER, WARNING, and CAUTION. These words are
used with the safety--alert symbol. DANGER identifies the most se-
rious 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 en-
hanced installation, reliability, or operation.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Before installing or servicing system, always turn off main
power to system. There may be more than one disconnect
switch. Turn off accessory heater power switch if applicable.
!WARNING
FIRE, EXPLOSION, ELECTRICAL SHOCK AND
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in personal injury
or unit damage.
A qualified installer or agency must use only
factory--authorized kits or accessories when modifying this
product.
WARNING
!
PERSONAL INJURY AND ENVIRONMENTAL
HAZARD
Failure to relieve system pressure could result in personal
injury and/or death.
1. Relieve pressure and recover all refrigerant beforeservicing
existing equipment, and before final unit disposal. Use all
service ports and open all flow--control devices, including
solenoid valves.
2. Federal regulations require that you do not vent refrigerant
into the atmosphere. Recover during system repairor final unit
disposal.
!WARNING
INTRODUCTION
The 48SD unit (see Fig. 1) is a fully self--contained, combination
Category I gas heating/electric cooling unit designed for outdoor
installation (See Fig. 3 and 4 for unit dimensions). All unit sizes
have return and discharge openings for both horizontal and
downflow configurations, and are factory shipped with all
downflow duct openings covered. Units may be installed either on
a rooftop, a cement slab, or directly on the ground if local codes
permit (See Fig. 5 for roof curb dimensions).
Models with an N in the fifth position of the model number are
dedicated Low NOx units designed for California installations.
These models meet the California maximum oxides of nitrogen
(NOx) emissions requirements of 40 nanograms/joule or less as
shipped from the factory and must be installed in California Air
Quality Management Districts or any other regions in North
America where a Low NOx rule exists.
NOTE: Low NOx requirements apply only to natural gas
installations.
RECEIVING AND INSTALLATION
Step 1—Check Equipment
IDENTIFY UNIT
The unit model number and serial number are stamped on the unit
information plate. Check this information against shipping papers.
INSPECT SHIPMENT
Inspect for shipping damage while unit is still on shipping pallet. If
unit appears to be damaged or is torn loose from its anchorage, have
it examined by transportation inspectors before removal. Forward
claim papers directly to transportation company. Manufacturer is
not responsible for any damage incurred in transit. Check all items
against shipping list. Immediately notify the nearest equipment
distribution office if any item is missing. To prevent loss ordamage,
leave all parts in original packages until installation.
Step 2—Provide Unit Support
For hurricane tie downs, contact distributor for details and PE
(Professional Engineering) Certificate if required.
ROOF CURB
Install accessory roof curb in accordance with instructions shipped
with curb (See Fig. 5). Install insulation, cant strips, roofing, and
flashing. Ductwork must be attached to curb.
IMPORTANT: The gasketing of the unit to the roof curb is critical
for a water tight seal. Install gasketing material supplied with the
roof curb. Improperly applied gasketing also can result in air leaks
and poor unit performance.
Curb should be level to within 1/4 in. (6.4 mm). This is necessary
for unit drain to function properly. Refer to accessory roof curb
installation instructions for additional information as required.
SLAB MOUNT
Place the unit on a solid, level concrete pad that is a minimum of 4
in. (102 mm)thick with 2 in. (51 mm)above grade(SeeFig.2).The
slab should extend approximately 2 in. (51 mm) beyond the casing
on all 4 sides of the unit. Do not secure the unit to the slab except
when required by local codes.
OPTIONAL
RETURN
AIR
OPENING
OPTIONAL
SUPPLY
AIR
OPENING
EVAP. COIL COND. COIL
2"
C99096
Fig. 2 -- Slab Mounting Details
GROUND MOUNT
The unit may be installed either on a slab or placed directly on the
ground, if local codes permit. Place the unit on level ground
prepared with gravel for condensate discharge.
Step 3—Field Fabricate Ductwork
Secure all ducts to roof curb and building structure on vertical
discharge units. Do not connect ductwork to unit. For horizontal
applications, unit is provided with flanges on the horizontal
openings. 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 applicable fire codes.
A minimum clearance is not required around ductwork. Cabinet
return--air static shall not exceed --.25 in. wc.
48SD

3
A07555
Fig. 3 -- 48SD018--036 Unit Dimensions
48SD

4
A07556
Fig. 4 -- 48SD042--060 Unit Dimensions
48SD

5
Gasket around
outer edge
Insulated
deck pan
Gasket around
duct
S/A
R/A
HVACunit
base
*Gasketing
outer flange
Flashing field
supplied
Roofing material
field supplied
Cant strip
field supplied
*Provided with roof curb
Roof
Ductwork
field supplied
Insulation(field
supplied)
Roof curb*
Wood nailer*
Gasketing
inner flange*
Screw
(NOTE A)
Roof Curb for Small Cabinet
Note A: When unit mounting screw is used,
retainer bracket must also be used.
HVAC unit
base
*Gasketing
outer flange
Flashing field
supplied
Roofing material
field supplied
Cant strip
field supplied
*Provided with roof curb
Roof
Ductwork
field supplied
Insulation(field
supplied)
Roof curb*
Wood nailer*
Gask eting
inner flange*
Screw
(NOTE A)
Roof Curb for Large Cabinet
Note A: When unit mounting screw is used,
retainer bracket must also be used.
A
BTyp.
Supply opening
(B x C)
Long
Support
D
F
Return opening
(B X C)
Insulated
deck pan
Short
Support
CTyp.
G
E
F
G
D
E
A05308
UNIT SIZE ODS CATALOG
NUMBER
A
IN. (MM)
B
IN. (MM)
C
IN. (MM)
D
IN. (MM)
E
IN. (MM)
F
IN. (MM)
G
IN. (MM)
48SD018--036 CPRFCURB006A00 8 (203) 11 (279) 16--1/2 (419) 28--3/4 (730) 30--3/8 (771) 44--5/16 (1126) 45--15/16 (1167)
CPRFCURB007A00 14 (356) 11 (279) 16--1/2 (419) 28--3/4 (730) 30--3/8 (771) 44--5/16 (1126) 45--15/16 (1167)
48SD042--060 CPRFCURB008A00 8 (203) 16--3/16 (411) 17--3/8 (441) 40--1/4 (1022) 41--15/16 (1065) 44--7/16 (1129) 46--1/16 (1169)
CPRFCURB009A00 14 (356) 16--3/16 (411) 17--3/8 (441) 40--1/4 (1022) 41--15/16 (1065) 44--7/16 (1129) 46--1/16 (1169)
NOTES:
1. Roof curb must be set up for unit being installed.
2. Seal strip must be applied, as required, to unit being installed.
3. Dimensions are in inches.
4. Dimension in ( ) are in millimeters.
5. Roof curb is made of 16--gauge steel.
6. Attach ductwork to curb (flanges of duct rest on curb).
7. Insulated panels: 1--in. (25 mm) thick fiberglass 1 lb. density.
8. When unit mounting screw is used (see Note A), a retainer bracket must be used as well. This bracket must also be used when required by code for hurricaneorseismic
conditions. This bracket is available through Micrometl.
Fig. 5 -- Roof Curb Dimensions
48SD

6
Step 4—Provide Clearances
The required minimum operating and service clearances are shown
in Fig. 3 and 4. Adequate combustion, ventilation and condenser air
must be provided in accordance with section 5.3, Air for
Combustion and Ventilation, of the National Fuel Gas Code ANSI
(American National Standards Institute) Z223.1 or applicable
provisions of local building code. In Canada, follow sections 7.2,
7.3, or 7.4 or Can/CGA (Canadian Gas Association) B149
Installation Codes or applicable provisions of local building code.
IMPORTANT: Do notrestrict outdoor airflow. An air restriction at
either the outdoor--air inlet or the fan discharge may be detrimental
to compressor life.
The condenser fan pulls air through the condenser coil and
discharges it through the top grille. Be sure that the fan discharge
does not recirculate to the condenser coil. Do not locate the unit in
either a corner or under an overhead obstruction. The minimum
clearance under a partial overhang (such as a normal house
overhang) is 48--in. (1219 mm) above the unit top. The maximum
horizontal extension of a partial overhang must not exceed 48--in.
(1219 mm).
Do not place the unit where water, ice, or snow from an overhang
or roof will damage or flood the unit. Do not install the unit on
carpeting or other combustible materials. Slab--mounted units
should be at least 4 in. (102 mm) above the highest expected water
and runoff levels. Do not use unit if it has been under water.
Step 5—Rig and Place Unit
Rigging and handling of this equipment can be hazardous for many
reasons due to the installation location (roofs, elevated structures,
etc.).
Only trained, qualified crane operators and ground support staff
should handle and install this equipment.
When working with this equipment, observe precautions in the
literature, on tags, stickers, and labels attached to the equipment, and
any other safety precautions that might apply.
Training for operators of the lifting equipment should include, but
not be limited to, the following:
1. Application of the lifter to the load, and adjustment of the
lifts to adapt to various sizes or kinds of loads.
2. Instruction in any special operation or precaution.
3. Condition of the load as it relates to operation of the lifting
kit, such as balance, temperature, etc.
Follow all applicable safety codes. Wear safety shoes and work
gloves.
INSPECTION
The lifting/rigging bracket is engineered and designed to be
installed only on Small Packaged Products. This bracket is to be
used to rig/lift a Small Packaged Product onto roofs or other
elevated structures.
Prior to initial use, and at monthly intervals, all rigging equipment
and straps should bevisually inspected for any damage, evidence of
wear, structural deformation, or cracks. Particular attention should
be paid to excessive wear at hoist hooking points and load support
areas. Equipment or straps showing any kind of wear in these areas
must not be used and should be discarded.
UNIT FALLING HAZARD
Failure to follow this warning could result in personal injury
or death.
Never stand beneath rigged units or lift over people.
!WARNING
PROPERTY DAMAGE HAZARD
Failure to follow this warning could result in personal
injury/death or property damage.
Rigging brackets for one unit use only. When removing a
unit at the end of its useful life, use a new set of brackets.
!WARNING
USE OF RIGGING BRACKET
Field Installation of Rigging Bracket (if not already installed)
1. Remove unit from shipping carton. Leave top shipping skid
on the unit for use as a spreader bar to prevent the rigging
straps from damaging the unit.If theskid isnot available, use
a spreader bar of sufficient length to protect the unit from
damage.
2. Remove 4 screws in unit corner posts.
3. Attach each of the 4 metal rigging brackets under the panel
rain lip (See Fig. 6). Use the screws removed in step 2 above
to secure the brackets to the unit.
PROPERTY DAMAGE HAZARD
Failure to follow this warning could result in personal
injury/death or property damage.
Rigging bracket MUST be under the rain lip to provide
adequate lifting.
!WARNING
PROPERTY DAMAGE HAZARD
Failure to follow this warning could result in personal
injury/death or property damage.
Do not strip screws when re--securing the unit. If a screw is
stripped, replace the stripped one with a larger diameter screw
(included). When straps are taut, the clevis should be a
minimum of 36 in. (914 mm) above the unit top cover.
!WARNING
Rigging/Lifting of Unit
1. Bend top of brackets down approximately 30 degrees from
the corner posts.
2. Attach straps of equal length to the rigging brackets at
opposite ends of the unit. Be sure straps are rated to hold the
weight of the unit (See Fig. 6).
3. Attach a clevis of sufficient strength in the middle of the
straps. Adjust the clevis location to ensure unit is lifted level
with the ground.
After the unit is placed on the roof curb or mounting pad, remove
the top crating, remove corner post screws and rigging brackets,
then re--install screws.
48SD

7
Table 1—Physical Data -- Unit 48SD
UNIT SIZE 48SD 018040 024040 024060 030040 030060 036060 036090 042060 042090
NOMINAL CAPACITY (ton) 1.5 2 2 2--1/2 2--1/2 3 3 3--1/2 3--1/2
OPERATING WEIGHT (lb)
(kg)
290
132
343
156
343
156
355
156
355
156
360
163
360
163
450
204
450
204
COMPRESSORS Scroll Scroll
REFRIGERANT (R-- 22)
Quantity (lb)
(kg)
5.3
2.4
5.9
2.7
5.9
2.7
6.0
2.7
6.0
2.7
7.2
3.3
7.2
3.3
7.8
3.5
7.8
3.5
REFRIGERANT METERING DEVICE
Orifice ID (in.)
Part Number
TXV AccuRater
NA
EA36YD097 0.065 0.065 0.070 0.070 0.080 0.080 0.084 0.084
CONDENSER COIL
Rows—Fins/in.
Face Area (sq ft) 1…21
13.6
2…21
10.2
2…21
10.2
2…21
11.9
2…21
11.9
2…21
113.6
2…21
13.6
2…21
19.4
2…21
19.4
CONDENSER FAN
Nominal Cfm
Diameter (in.)
Motor Hp
(Rpm)
2200
22
1/8 (825)
2200
22
1/8 (825)
2200
22
1/8 (825)
2800
22
1/8 (825)
2800
22
1/8 (825)
3000
22
1/8 (825)
3000
22
1/8 (825)
3500
22
1/8 (825)
3500
22
1/8 (825)
EVAPORATOR COIL
Rows—Fins/in.
Face Area (sq ft) 3…17
3.7
3…17
3.7
3…17
3.7
3…17
3.7
3…17
3.7
4…17
3.7
4…17
3.7
3…17
4.7
3…17
4.7
EVAPORATOR BLOWER
Nominal Airflow (Cfm)
Size (in.)
Size (mm)
Motor Hp
(RPM)
600
10x10
254x254
1/4 (825)
800
10x10
254x254
1/3 (1050)
800
10x10
254x254
1/3 (1050)
1000
10x10
254x254
1/3 (1050)
1000
10x10
254x254
1/3 (1050)
1200
10x10
254x254
1/2 (1000)
1200
10x10
254x254
1/2 (1000)
1400
11x 10
279x254
1/2 (1075)
1400
11x10
279x254
1/2 (1075)
FURNACE SECTION*
Burner Orifice No. (Qty—Drill Size) Natural Gas
Burner Orifice No. (Qty—Drill Size) Propane
2...44
2...50
2...44
2...50
2...38
2...46
2...44
2...50
2...38
2...46
2...38
2...46
3...38
3...46
2...38
2...46
3...38
3...46
RETURN--AIR FILTERS Throwaway (in.)†
(mm)
20x20x1
508x508x25
24x30x1
610x762x25
UNIT SIZE 48SD 048090 048115 048130 060090 060115 060130
NOMINAL CAPACITY (ton) 4 4 4 5 5 5
OPERATING WEIGHT (lb)
kg
480
218
480
218
480
218
484
220
484
220
484
220
COMPRESSORS Scroll
REFRIGERANT (R--22)
Quantity (lb)
(kg)
12.4
5.6
12.4
5.6
12.4
5.6
12.0
5.4
12.0
5.4
12.0
5.4
REFRIGERANT METERING DEVICE
Orifice ID (in.)
AccuRater
0.088 0.088 0.088 0.098 0.098 0.098
CONDENSER COIL
Rows—Fins/in.
Face Area (sq ft) 2…21
19.4
2…21
19.4
2…21
19.4
2…21
19.4
2…21
19.4
2…21
19.4
CONDENSER FAN
Nominal Cfm
Diameter (in.)
Motor Hp (Rpm)
3500
22
1/4 (1100)
3500
22
1/4 (1100)
3500
22
1/4 (1100)
4200
22
1/4 (1100)
4200
22
1/4 (1100)
4200
22
1/4 (1100)
EVAPORATOR COIL
Rows—Fins/in.
Face Area (sq ft) 3…17
5.7
3…17
5.7
3…17
5.7
4…17
5.7
4…17
5.7
4…17
5.7
EVAPORATOR BLOWER
Nominal Airflow (Cfm)
Size (in.)
Size (mm)
Motor Hp (RPM)
1600
11x10
279x254
1/2 (1075)
1600
11x10
279x254
1/2 (1075)
1600
11x10
279x254
1/2 (1075)
1750
11x10
279x254
1 (1040)
1750
11x10
279x254
1 (1040)
1750
11x10
279x254
1 (1040)
FURNACE SECTION*
Burner Orifice No. (Qty—Drill Size) Natural Gas
Burner Orifice No. (Qty—Drill Size) Liquid Propane 3...38
3...46
3...33
3...42
3...31
3...41
3...38
3...46
3...33
3...42
3...31
3...41
RETURN--AIR FILTERS Throwaway
(in.)†
(mm)
24x36x1
610x914x25
LEGEND
* Based on altitude of 0 to 2000 feet (0 to 610 m).
{Required filter sizes on shown are based on the larger of the ARI (Air Conditioning and Refrigeration Institute) rated cooling airflow or the heating airflow
velocity of 300 ft/min for throwaway type or 450 ft/min for high---capacity type. Air filter pressure drop for non---standard filters must not exceed 0.08 in. wc.
48SD

8
12
43
C00070b
DETAIL A
A05161
CORNER WEIGHTS (SMALL CABINET) CORNER WEIGHTS (LARGE CABINET)
Unit 018 024 030 036 Unit 042 048 060
lb kg lb kg lb kg lb kg lb kg lb kg lb kg
Unit Only
Weight 290 132 343 156 355 161 360 163 Unit Only Weight 450 204 480 218 484 220
Corner Weight
175 34 69 31 75 34 74 34 Corner Weight 190 41 97 44 98 45
Corner Weight
262 28 53 24 56 25 55 25 Corner Weight 272 33 74 34 75 34
Corner Weight
397 44 83 38 81 37 86 39 Corner Weight 3110 50 116 53 118 54
Corner Weight
456 25 138 63 143 65 145 66 Corner Weight 4178 81 193 88 193 88
Rigging Weight 309 140 353 160 365 166 370 168 Rigging Weight 465 211 495 225 499 226
Shipping
Weight 344 156 383 173 395 179 400 181 Shipping Weight 510 231 540 245 544 247
Fig. 6 -- 48SD Unit Corner Weights and Suggested Rigging
Step 6—Connect Condensate Drain
NOTE: When installing condensate drain connection be sure to
comply with local codes and restrictions.
Model 48SD disposes of condensate water through a 3/4 in. NPT
fitting which exits through the base on the evaporator coil access
side. See Fig. 3 & 4 for location.
Condensate water can be drained directly onto the roof in rooftop
installations (where permitted) or onto a gravel apron in ground
level installations. Install a field--supplied 2--in. condensate trap at
the end of condensate connection to ensure proper drainage. Make
sure that the outlet of the trap is at least 1 in. (25 mm) lower than the
drain--pan condensate connection to prevent the pan from
overflowing (See Fig. 7). Prime the trap with water. When using a
gravel apron, make sure it slopes away from the unit.
TRAP
OUTLET
2" min.
1" min.
C00009
Fig. 7 -- Condensate Trap
Connect a drain tube using a minimum of 3/4--in. PVC or 3/4--in.
copper pipe (all field--supplied) at the outlet end of the 2--in. trap.
Do not undersize the tube. Pitch the drain tube downward at a slope
of at least 1--in. (25 mm) for every 10 ft (3 m) of horizontal run. Be
sure to check the drain tube for leaks.
Step 7—Install Flue Hood
The flue assembly is secured and shipped in the return air duct.
Remove duct cover to locate the assembly (See Fig. 9 and 10).
NOTE: Dedicated low NOx models MUST be installed in
California Air Quality Management Districts where a Low NOx
rule exists.
These models meet the California maximum oxides of nitrogen
(NOx) emissions requirements of 40 nanograms/joule or less as
shipped from the factory.
NOTE: Low NOx requirements apply only to natural gas
installations.
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in personal injury
or death.
The venting system is designed to ensure proper venting. The
flue hood assembly mustbe installed as indictedin thissection
of the unit installation instructions.
!WARNING
Install the flue hood as follows:
1. This installation must conform with local building codes and
with the National Fuel Gas Code (NFGC),ANSI Z223.1 (in
Canada, CAN/CGA B149.1, and B149.2) or NFPA
(National Fire Protection Association) latest revision. Refer
to Provincial and local plumbing or wastewater codes and
other applicable local codes.
2. Remove flue hood from shipping location (inside the return
section of the blower compartment--see Fig. 9 & 10). Re-
move the return duct cover to locate the flue hood. Place flue
hood assembly over flue panel. Orient screw holes in flue
hood with holes in the flue panel.
3. Secure flue hood to flue panel by inserting a single screw on
the right side and the left side of the hood.
48SD

9
Step 8—Install Gas Piping
The gas supply pipe enters the unit through the access hole
provided. The gas connection to the unit is made to the 1/2--in. FPT
gas inlet on the gas valve.
Install a gas supply line that runs to the heating section. Refer to
Table 2 and the NFGCfor gaspipe sizing.Do notuse cast--iron pipe.
It is recommended that a black iron pipe is used. Check the local
utility for recommendations concerning existing lines. Size gas
supply piping for 0.5 in. wc maximum pressure drop. Never use
pipe smaller than the 1/2--in. FPT gas inlet on the unit gas valve.
For natural gas applications, the gas pressure at unit gas connection
must not be less than 4.0 in. wc or greater than 13 in. wc while the
unit is operating. For propane applications, the gas pressure must
not be less than 7.0 in. wc or greater than 13 in. wc at the unit
connection.
A 1/8--in. NPT plugged tapping, accessible for test gauge
connection, must be installed immediately upstream of the gas
supply connection to the gas valve.
When installing the gas supply line, observe local codes pertaining
to gas pipe installations. Refer to the NFGC ANSI Z223.1--2005
NFPA latest edition (in Canada, CAN/CGA B149.1).
NOTE: In the state of Massachusetts:
1. Gas supply connections MUST be performed by a licensed
plumber or gas fitter.
2. When flexible connectors are used, the maximum length
shall not exceed 36 inches (915 mm).
3. When lever handle type manual equipment shutoff valves
are used, they shall be T--handle valves.
4. The use of copper tubing for gas piping is NOT approved by
the state of Massachusetts.
In the absence of local building codes, adhere to the following
pertinent recommendations:
1. Avoid low spots in long runs of pipe. Grade all pipe 1/4 in.
(6.4 mm) for every 15 ft (5 m) of length to prevent traps.
Grade all horizontal runs downward to risers. Use risers to
connect to heating section and to meter.
2. Protect all segments of piping system against physical and
thermal damage. Support all piping with appropriate straps,
hangers, etc. Use a minimum of one hanger every 6 ft. (1.8
m). For pipe sizes larger than 1/2 in. (13 mm), follow
recommendations of national codes.
3. Apply joint compound (pipe dope) sparingly and only to
male threads of joint when making pipe connections. Use
only pipe dope that is resistant to action of liquefied
petroleum gases as specified by local and/or national codes.
Never use Teflon tape.
4. Install sediment trap in riser leading to heating section (See
Fig. 8). This drip leg functions as a trap for dirt and
condensate.
5. Install an accessible, external, manual main shutoff valve in
gas supply pipe within 6 ft (1.8 m) of heating section.
6. Install ground--joint union close to heating section between
unit manual shutoff and external manual main shut--off
valve.
7. Pressure test all gas piping in accordance with local and
national plumbing and gas codes before connecting piping
to unit.
OUT
TEE
NIPPLE
CAP
IN
C99020
Fig. 8 -- Sediment Trap
NOTE: Pressure test the gas supply system after the gas supply
piping is connected to the gas valve. The supply piping must be
disconnected from the gas valve during the testing of the piping
systems when test pressure is in excess of 0.5 psig. Pressure test the
gas supply piping system at pressures equal to or less than 0.5 psig.
The unit heating section must be isolated from the gas piping system
by closing the external main manual shutoff valve and slightly
opening the ground--joint union.
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal injury,
death and/or property damage.
--Connect gas pipe to unit using a backup wrench to avoid
damaging gas controls.
--Never purge a gas line into a combustion chamber. Never test
for gas leaks with an open flame. Use a commercially available
soap solution made specifically for the detection of leaks to
check all connections.
--Use proper length of pipe to avoid stress on gas control
manifold.
--If a flexible connector is required or allowed by authority
having jurisdiction, black iron pipe shall be installed at furnace
gas valve and extend a minimum of 2 in. (51 mm) outside
furnace casing.
--If codes allow a flexible connector, always use a new
connector. do not use a connector which has previously
serviced another gas appliance.
!WARNING
8. Check for gas leaks at the field--installed and
factory--installed gas lines after all piping connections have
been completed. Use soap--and--water solution (or method
specified by local codes and/or regulations).
Step 9—Install Duct Connections
The unit has duct flanges on the supply-- and return--air openings on
the side and bottom of the unit. For downshot applications, the
ductwork connects to the roof curb (See Fig. 3 and 4 for connection
sizes and locations).
CONFIGURING UNITS FOR DOWNFLOW (VERTICAL)
DISCHARGE
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Before installing or servicing system, always turn off main
power to system. There may be more than one disconnect
switch.
!WARNING
48SD

10
Table 2—Maximum Gas Flow Capacity*
NOMINAL
IRON PIPE
SIZE (IN.)
INTERNAL
DIAMETER
(IN.)
LENGTH OF PIPE (FT)†
10 20 30 40 50 60 70 80 90 100 125 150 175 200
1/2 .622 175 120 97 82 73 66 61 57 53 50 44 40 — —
3/4 .824 360 250 200 170 151 138 125 118 110 103 93 84 77 72
11.049 680 465 375 320 285 260 240 220 205 195 175 160 145 135
1--1/4 1.380 1400 950 770 600 580 530 490 460 430 400 360 325 300 280
1--1/2 1.610 2100 1460 1180 990 900 810 750 690 650 620 550 500 460 430
*Capacity of pipe in cu ft of gas per hr for gas pressure of 0.5 psig or less. Pressure drop of 0.5--in. wc (based on a 0.60 specific gravity gas). Refer to Table, National Fire Protec-
tion Association NFPA 54.
{This length includes an ordinary number of fittings.
1. Open all electrical disconnects before starting any service
work.
2. Remove horizontal (metal) duct covers to access vertical
(downflow) discharge duct knockouts in unit base.
3. Use a screwdriver and hammer to remove the panels in the
bottom of the unit base (See Fig. 10).
4. If unit ductwork is to be attached to vertical opening flanges
on the unit base (jackstand applications only), do so at this
time.
PROPERTY DAMAGE HAZARD
Failure to follow this caution may result in property damage.
Collect ALL screws that were removed. Do not leave screws
on rooftop as permanent damage to the roof may occur.
CAUTION
!
5. It is recommended that the base insulation around the
perimeter of the vertical return--air opening be secured to the
base with aluminum tape. Applicable local codes may
require aluminum tape to prevent exposed fiberglass.
6. Cover both horizontal duct openings with the provided duct
covers. Ensure opening is air-- and watertight.
7. After completing unit conversion, perform all safety checks
and power up unit.
NOTE: The design and installation of the duct system must be in
accordance with the standards of the NFPA for installation of
nonresidence--type air conditioning and ventilating systems, NFPA
90A or residence--type, NFPA 90B; and/or local codes and
ordinances.
SUPPLY
DUCT
OPENING
RETURN
DUCT
OPENING
VENT HOOD
SHIPPING
LOCATION
A05143
Fig. 9 -- Supply and Return Duct Opening
DUCT COVERS REMOVED
C99012
Fig. 10 -- Vertical Duct Cover Removed
Adhere to the following criteria when selecting, sizing, and
installing the duct system:
1. Units are shipped for horizontal duct installation (by
removing duct covers).
2. Select and size ductwork, supply--air registers, and
return--air grilles according to American Society of Heating,
Refrigeration and Air Conditioning Engineers (ASHRAE)
recommendations.
3. Use flexible transition between rigid ductwork and unit to
prevent transmission of vibration. The transition may be
screwed or bolted to duct flanges. Use suitable gaskets to en-
sure weather--tight and airtight seal.
4. All units must have field--supplied filters or accessory filter
rack installed in the return--air side of the unit.
Recommended sizes for filters are shown in Table 1.
5. Size all ductwork for maximum required airflow (either
heating or cooling) for unit being installed. Avoid abrupt
duct size increases or decreases or performance may be
affected.
6. Adequately insulate and weatherproof all ductwork located
outdoors. Insulate ducts passing through unconditioned
space, and use vapor barrier in accordance with latest issue
of Sheet Metal and Air Conditioning Contractors National
Association (SMACNA) and Air Conditioning Contractors
of America (ACCA) minimum installation standards for
heating and air conditioning systems. Secure all ducts to
building structure.
7. Flash, weatherproof, and vibration isolate all openings in
building structure in accordance with local codes and good
building practices.
48SD

11
Step 10—Install Electrical Connections
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
The unit cabinet must have an uninterrupted, unbroken
electrical ground. This ground may consist of an electrical
wire connected to the unit ground screw in the control
compartment, or conduit approved for electrical ground when
installed in accordance with NEC, ANSI/NFPA American
National Standards Institute/National Fire Protection
Association (latest edition) (in Canada, Canadian Electrical
Code CSA C22.1) and local electrical codes.
!WARNING
UNIT COMPONENT DAMAGE HAZARD
Failure to follow this caution may result in damage to the unit
being installed.
1. Make all electrical connections in accordance with NEC
ANSI/NFPA (latest edition) and local electrical codes
governing such wiring. In Canada, all electrical
connections must be in accordance with CSA standard
C22.1 Canadian Electrical Code Part 1 and applicable local
codes. Refer to unit wiring diagram.
2. Use only copper conductor for connections between
field--supplied electrical disconnect switch and unit. DO
NOT USE ALUMINUM WIRE.
3. Be sure that high--voltage power to unit is within operating
voltage range indicated on unit rating plate. On 3--phase
units, ensure phases are balanced within 2 percent. Consult
local power company for correction of improper voltage
and/or phase imbalance.
4. Insulate low--voltage wires for highest voltage contained
within conduit when low--voltage control wiresare in same
conduit as high--voltage wires.
5. Do not damageinternal componentswhen drilling through
any panel to mount electrical hardware, conduit, etc.
!CAUTION
HIGH--VOLTAGE CONNECTIONS
When routing power leads into unit, use only copper wire between
disconnect and unit. The high voltage leads should be in a conduit
until they enter the duct panel; conduit termination at the duct panel
must be watertight.
The unit must have a separate electrical service with a
field--supplied, waterproof disconnectswitch mounted at, orwithin
sight from, the unit. Refer to the unit rating plate, NEC and local
codes for maximum fuse/circuit breaker size and minimum circuit
amps (ampacity) for wire sizing.
The field--supplied disconnect switch box may be mounted on the
unit over the high--voltage inlet hole when the standard power and
low--voltage entry points are used (See Fig. 3 and 4 for acceptable
location).
See unit wiring label and Fig. 11 for reference when making high
voltage connections. Proceed as follows to complete the
high--voltage connections to the unit.
Single phase units:
1. Run the high--voltage (L1, L2) and ground lead into the
control box.
2. Connect ground lead to chassis ground connection.
3. Locate the black and yellow wires connected to the line side
of the contactor.
4. Connect field L1 to black wire connected to 11 terminal of
the compressor contactor.
5. Connect field wire L2 to yellow wire connected to 23
terminal of the compressor contactor.
Three--phase units:
1. Run the high--voltage (L1, L2, L3) and ground lead into the
control box.
2. Connect ground lead to chassis ground connection.
3. Locate the black and yellow wires connected to the line side
of the contactor, and blue wire from compressor.
4. Connect field L1 to black wire on connected to 11 terminal
of the compressor contactor.
5. Connect field wire L3 to yellow wire connected to 13
terminal of the compressor contactor.
6. Connect field wire L2 to blue wire from compressor.
SPECIAL PROCEDURES FOR 208--V OPERATION
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Before making any wiring changes,make sure the gas supply
is switched off first. Then switch off the power supply to the
unit and install lockout tag.
!WARNING
CONTROL VOLTAGE CONNECTIONS
Do not use any type of power--stealing thermostat. Unit control
problems may result.
Use no. 18 American Wire Gage (AWG) color--coded, insulated
(35_C minimum) wires to make the control voltage connections
between the thermostat and the unit. If the thermostat is located more
than 100 ft from the unit (as measured along the control voltage
wires), use no. 16 AWG color--coded, insulated (35_C minimum)
wires.
Standard Connection
Remove knockout hole located in the flue panel adjacent to the
control access panel (See Fig. 3 and 4). Remove the rubbergrommet
from the installer’s packet (included with unit) and install grommet
in the knockout opening. Provide a drip loop before running wire
through panel.
POWER
SUPPLY
FIELD-SUPPLIED
FUSED DISCONNECT
HIGH VOLTAGE
POWER LEADS
(SEE UNIT WIRING
LABEL)
GR
CONTROL BOX
SPLICE BOX
LOW-VOLTAGE
POWER LEADS
(SEE UNIT
WIRING LABEL)
W
Y
G
R
C
WHT(W1)
YEL(Y)
GRN(G)
RED(R)
BRN(C)
THERMOSTA
T
(TYPICAL)
A05144
Fig. 11 -- High-- and Control--Voltage Connections
48SD

12
Run the low--voltage leads from the thermostat, through the inlet
hole, and into unit low--voltage splice box (see Fig. 13).
Locate five 18--gage wires leaving control box. These low--voltage
connection leads can be identified by the colors red, green, yellow,
brown, and white (See Fig. 11). Ensure the leads are long enough
to be routed into the low--voltage splice box (located below right
side of control box). Route leads through hole in bottom of control
box and make low--voltage connections (See Fig. 11). Secure all cut
wires, so that they do not interfere with operation of unit.
HEAT ANTICIPATOR SETTING
See thermostat instructions for anticipator and cycle rate setup
details.
NOTE: For thermostat selection purposes, use 0.18 amp for the
approximate required setting. Failure to make a proper heat
anticipator adjustment will result in improper operation, discomfort
to the occupants of the conditioned space, and inefficient energy
utilization; however, the required setting may be changed slightly
to provide a greater degree of comfort for a particular installation.
TRANSFORMER PROTECTION
The transformer is of the energy--limiting type. It is set to withstand
a 30--sec. overload or shorted secondary condition.
PRE--START--UP
FIRE, EXPLOSION, ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
1. Follow recognized safety practices and wear protective
goggles when checking or servicing refrigerant system.
2. Do not operate compressor or provide any electric power
to unit unless compressor terminal cover is in place and
secured.
3. Do not remove compressor terminal cover until all
electrical sources are disconnected and tagged.
4. Relieve and recover all refrigerant from system before
touching or disturbing anything inside terminal box if
refrigerant leak is suspected around compressor terminals.
5. Never attempt to repair soldered connection while
refrigerant system is under pressure.
6. Do not use torch to remove any component. System
contains oil and refrigerant under pressure.
To remove a component, wear protective goggles and
proceed as follows:
a. Shut off electrical power to unit and install lockout
tag.
b. Relieve and reclaim all refrigerant from system
using both high-- and low--pressure ports.
c. Cut component connecting tubing with tubing
cutter and remove component from unit.
d. Carefully unsweat remaining tubing stubs when
necessary. Oil can ignite when exposed to torch
flame.
!WARNING
Use the Start--Up Checklist supplied at the end of this book and
proceed as follows to inspect and prepare the unit for initial start--up:
1. Remove access panel.
2. Read and follow instructions on all DANGER, WARNING,
CAUTION, and INFORMATION labels attached to, or
shipped with unit.
3. Make the following inspections:
a. Inspect for shipping and handling damage, such as
broken lines, loose parts, disconnected wires, etc.
b. Inspect for oil at all refrigerant tubing connections and on
unit base. Detecting oil generally indicates a refrigerant
leak.
c. Leak--test all refrigerant tubing connections using
electronic leak detector, or liquid--soap solution. If a
refrigerant leak is detected, see following Check for
Refrigerant Leaks section.
d. Inspect all field-- and factory--wiring connections. Be
sure that connections are completed and tight.
e. Ensure wires do not touch refrigerant tubing or sharp
sheet metal edges.
f. Inspect coil fins. If damaged during shipping and
handling, carefully straighten fins with a fin comb.
FIRE, EXPLOSION HAZARD
Failure to follow this warning could result in personal injury,
death or property damage.
Do not purge gas supply into the combustion chamber.Do not
use a match or other open flame to check for gas leaks.
!WARNING
4. Verify the following conditions:
a. Make sure gas line is free of air. Before lighting the unit
for the first time, perform the following with the gas valve
in the OFF position:
NOTE: If the gas supply pipe was not purged before connecting the
unit, it will be full of air. It is recommended that the ground joint
union be loosened, and the supply line be allowed to purge until the
odor of gas is detected. Never purge gas lines into a combustion
chamber. Immediately upon detection of gas odor, retighten the
union. Allow 5 minutes to elapse, then light unit.
b. Make sure that condenser--fan blade is correctly
positioned in fan orifice. As a general rule , the top 1/3 of
condenser--fan blade should be within fan orifice venturi.
c. Ensure fan hub is positioned correctly with respect to
motor housing (See Fig. 12).
d. Make sure that air filter(s) is in place.
e. Make sure that condensate drain trap is filled with water
to ensure proper drainage.
f. Make sure that all tools and miscellaneous loose parts
have been removed.
FAN GRILLE
MOTOR
1/8" MAX BETWEEN
MOTOR AND FAN HUB MOTOR SHAFT
1/2ý
C99009
Fig. 12 -- Fan Blade Clearance
START--UP
Step 1—CHECK FOR REFRIGERANT LEAKS
Proceed as follows to locate and repair a refrigerant leak and to
charge the unit:
1. Locate leak and make sure that refrigerant system pressure
has been relieved and reclaimed from both high-- and
low--pressure ports.
2. Repair leak following accepted practices.
48SD

13
NOTE: Install a filter drier whenever the system has been opened
for repair.
3. Add a small charge of R--22 refrigerant vapor to system and
leak--test unit.
4. Recover refrigerant from refrigerant system and evacuate to
500 microns if no additional leaks are found.
5. Charge unit with R--22 refrigerant, using a volumetric
charging cylinder or accurate scale. Refer to unit rating plate
for required charge. Be sure to add extra refrigerant to
compensate for internal volume of filter drier.
STEP 2—START--UP HEATING AND MAKE ADJUST-
MENTS
Complete the required procedures given in the Pre--Start--Up
section before starting the unit. Do not jumper any safety devices
when operating the unit. Make sure that burner orifices are properly
aligned. Unstable operation my occur when the burner orifices in
the manifold are misaligned.
Follow the lighting instructions on the heating section operation
label (located inside the burner or blower access door) to start the
heating section.
NOTE: Make sure that gas supply has been purged, and that all gas
piping has been checked for leaks.
MANIFOLD PIPE PLUG
LOW-VOLTAGE
SPLICE BOX
A07568
Fig. 13 -- Burner Assembly
MANIFOLD
BURNER
BURNER FLAME
C99021
Fig. 14 -- Monopoly Burner
CHECK HEATING CONTROL
Start and check the unit for proper heating control operation as
follows (see furnace lighting instructions located inside burner or
blower access panel):
1. Place room thermostat SYSTEM switch in the HEAT
position and the fan switch is placed in AUTO position.
2. Set the heating temperature control of the thermostat above
room temperature.
3. The induced--draft motor will start.
4. After a call for heating, the main burner should light within
5 sec. If the burners do not light, there is a 22--sec. delay
before another 5--sec. try. If the burners still do not light, this
sequence is repeated. If the burners do not light within 15
minutes from the initial call for heat, there is a lockout. To
reset the control, break the 24--v power to W.
5. The evaporator fan will turn on 45 sec. after the flame has
been established. The evaporator fan will turn off 45 sec.
after the thermostat has been satisfied.
CHECK GAS INPUT
Check gasinput and manifold pressureafter unitstart--up (SeeTable
3). If adjustment is required proceed as follows:
SThe rated gas inputs shown in Table 3 are for altitudes
from sea level to 2000 ft abovesea level. These inputs are
based on natural gas with a heating value of 1050 Btu/ft3
at 0.65 specific gravity, or propane gas with a heating
value of 2500 Btu/ft3at 1.5 specific gravity.
SFor elevations above 2000 ft (610 m), reduce input 4%
for each 1000 ft (305 m) above sea level. For example at
2001 ft (610 m) a 12% total derate is required.
SWhen the gas supply being used has a different heating
value or specific gravity, refer to national and local codes,
or contact your distributor to determine the required
orifice size.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in reduced unit and/or
component life.
Do Not redrill an orifice. Improper drilling (burrs,
out--of--round holes, etc.) can cause excessive burner noise
and misdirection of burner flame. If orifice hole appears
damaged or it is suspected to have been redrilled, check orifice
hole with a numbered drill bit of correct size.
!CAUTION
ADJUST GAS INPUT
The gas input to the unit is determined by measuring the gas flow
at the meter or by measuring the manifold pressure. Measuring the
gas flow at the meter is recommended for natural gas units. The
manifold pressure must be measured to determine the input of
propane gas units.
Measure Gas Flow (Natural Gas Units)
Minor adjustment to the gas flow can be made by changing the
manifold pressure. The manifold pressure must be maintained
between 3.4 and 3.6 in. wc.
If larger adjustments are required, change main burner orifices
following the recommendations of national and local codes.
NOTE: All other appliances that use thesame meter must be turned
off when gas flow is measured at the meter.
Proceed as follows:
1. Turn off gas supply to unit.
48SD

14
Table 3—Heating Inputs
HEATING INPUT
(BTUH)
NUMBER
OF
GAS SUPPLY PRESSURE (IN. WC)
MANIFOLD
PRESSURE
(IN
WC)
NUMBER
OF
ORIFICES
Natural{Propane*{
MANIFOLD
PRESSURE
(IN
.
WC)
ORIFICES
Min Max Min Max Natural{Propane*†
40,000 24.0 13.0 4.0 13.0 3.5 3.5
60,000 24.0 13.0 4.0 13.0 3.5 3.5
90,000 34.0 13.0 4.0 13.0 3.5 3.4
115,000 34.0 13.0 4.0 13.0 3.5 3.7
130,000 34.0 13.0 4.0 13.0 3.5 3.5
*When a unit is converted to propane, different size orifices must be used. See separate, natural--to--propane conversion kit instructions.
{Based on altitudes from sea level to 2000 ft above sea level. For altitudes above 2000 ft, reduce input rating 4 percent for each additional 1000 ft above sea level. In Canada,
from 2000 ft above sea level to 4500 ft above sea level, derate the unit 10 percent.
2. Remove pipe plug on manifold (See Fig. 13) and connect
manometer. Turn on gas supply to unit.
3. Record number ofsecondsforgas meter test dial to makeone
revolution.
4. Divide number of seconds in Step 3 into 3600 (number of
seconds in one hr).
5. Multiply result of Step 4 by the number of cubic feet (cu ft)
shown for one revolution of test dial to obtain cubic feet (cu
ft) of gas flow per hour.
6. Multiply result of Step 5 by Btu heating value of gas to
obtain total measured input in Btuh. Compare this valuewith
heating input shown in Table 3 (Consult the local gas
supplier if the heating value of gas is not known).
EXAMPLE: Assume that the size of test dial is 1 cu ft, one
revolution takes 32 sec, and the heating value of the gas is 1050
Btu/ft3. Proceed as follows:
1. 32 sec. to complete one revolution.
2. 3600 ÷32 = 112.5.
3. 112.5x1=112.5ft3ofgasflow/hr.
4. 112.5 x 1050 = 118,125 Btuh input.
If the desired gas input is 115,000 Btuh, only a minor change in the
manifold pressure is required.
Observe manifold pressure and proceed as follows to adjust gas
input:
1. Removecover screw over regulator adjustmentscrew on gas
valve.
2. Turn regulator adjustment screw clockwise to increase gas
input, or turn regulator adjustment screw counterclockwise
to decrease input. Manifold pressure must be between 3.4
and 3.6 in. wc.
FIRE AND UNIT DAMAGE HAZARD
Failure to follow this warning could result in personal injury
or death and/or property damage.
Unsafe operation of the unit may result ifmanifold pressure is
outside this range.
!WARNING
3. Replace cover screw cap on gas valve.
4. Turn off gas supply to unit. Remove manometer from
pressure tap and replace pipe plug on gas valve. Turn on gas
to unit and check for leaks.
Measure Manifold Pressure (Propane Units)
The main burner orifices on a propane gas unit are sized for the unit
rated input when the manifold pressure reading matches the level
specified in Table 3.
Proceed as follows to adjust gas input on a propane gas unit:
1. Turn off gas to unit.
2. Removepipe plug on manifold and connect manometer (See
Fig. 13).
3. Turn on gas to unit.
4. Remove cover screw over regulator adjustment screw on gas
valve.
5. Adjust regulator adjustment screw to the correct manifold
pressure, as specified in Table 3. Turn adjusting screw
clockwise to increase manifold pressure, or turn adjusting
screw counterclockwise to decrease manifold pressure.
6. Replace cover screw.
7. Turn off gas to unit. Remove manometer from pressure tap.
Replace pipe plug on gas valve, then turn on gas to unit.
Check for leaks.
CHECK BURNER FLAME
With burner access panel removed, observe the unit heating
operation. Watch the burner flames to see if they are light blue and
soft in appearance, and that the flames are approximately the same
for each burner. Propane will have blue flame (See Fig. 14). Refer
to the Maintenance section for information on burner removal.
AIRFLOW AND TEMPERATURE RISE
The heating section for each size unit is designed and approved for
heating operation within the temperature--rise range stamped on the
unit rating plate.
Table 8 shows the approved temperature rise range for each heating
input, and the air delivery cfm at various temperature rises. The
heating operation airflow must produce a temperature rise that falls
within the approved range.
Refer to Indoor Airflow and Airflow Adjustments section to adjust
heating airflow when required.
HEATING SEQUENCE OF OPERATION
(See Fig. 15--17 and unit wiring label.)
On a call for heating, terminal W of the thermostat is energized,
starting the induced--draft motor. When the hall--effectsensor on the
induced--draft motor senses that it has reached the required speed,
the burner sequence begins. This function is performed by the
integrated gas control (IGC). The indoor (evaporator)--fan motor is
energized 45 sec after flame is established. When the thermostat is
satisfied and W is de--energized, the burners stop firing and the
indoor (evaporator) fan motor shuts off after a 45--sec time--off
delay.
Please note that the ignition control board (IGC) has the capability
to automatically reduce theindoor fanmotoron and off delays inthe
event of high duct static and/or partially--clogged filter. An
adjustment of fan delays by the ignition control board is indicated
by a flash code “1” on the LED on the IGC.
An LED (light--emitting diode) indicator is provided on the control
board to monitor operation. The control board is located by
removing the burner access panel. During normal operation, the
LED is continuously on (See Table 4 for status codes).
48SD 48SD

15
A07439
Fig. 15 -- 208/230--1--60 Wiring Diagram
48SD

16
A07569
Fig. 16 -- 208/230--3--60 Wiring Diagram
48SD

17
A07570
Fig. 17 -- 460--3--60 Wiring Diagram
48SD

18
LIMIT SWITCHES
Normally closed limit switch (LS) completes the control circuit.
Should the leaving--air temperature rise above the maximum
allowable temperature, the limit switch opens and the control circuit
“breaks.” Any interruption in the control circuit instantly closes the
gas valve and stops gas flow to the burners and pilot. The blower
motor continues to run until LS resets.
When the air temperature at the limit switch drops to the
low--temperature setting of the limit switch, the switch closes and
completes the control circuit. The direct--spark ignition system
cycles and the unit returns to normal heating operation.
Table 4—LED Indications
STATUS CODE LED INDICATION
Normal Operation2On
Hardware Failure Off
Fan On/Off Delay Modified21Flash
Limit Switch Fault 2 Flashes
Flame Sense Fault 3 Flashes
Four Consecutive Limit Switch Faults 4 Flashes
Ignition Lockout Fault 5 Flashes
Induced--Draft Motor Fault 6 Flashes
Rollout Switch Fault 7 Flashes
Internal Control Fault 8 Flashes
Temporary Lock--Out 1 hr auto reset19 Flashes
NOTES:
1. This code indicates an internal processor fault that will reset itself in one hr.
Fault can be caused by stray RF signals in the structure or nearby. This is a UL
requirement.
2. LED indicates acceptable operation. Do not change ignition control board.
3. When W1 is energized the burners will remain on for a minimum of 60 sec.
4. If more than one error mode exists they will be displayed on the LED in se-
quence.
ROLLOUT SWITCH
The function of the rollout switch is to close the main gas valve in
the event of flame rollout. The switch is located above the main
burners. When the temperature at the rollout switch reaches the
maximum allowable temperature, the control circuit trips, closing
the gas valve and stopping gas flow to the burners. The indoor
(evaporator) fan motor (IFM) and induced draft motor continue to
run until switch is reset. The IGC LED will display FAULT CODE
7.
Step 3—START--UP COOLING AND MAKE ADJUST-
MENTS
Complete the required procedures given in the Pre--Start--Up
section before starting the unit. Do not jumper any safety devices
when operating the unit. Do not operate the compressor when the
outdoor temperature is below 40°F(4.4°C) (unless accessory
low--ambient kit is installed). Do not rapid--cycle the compressor.
Allow 5 minutes between on cycles to prevent compressor damage.
CHECKING COOLING CONTROL OPERATION
Start and check the unit for proper cooling control operation as
follows:
1. Place room thermostat SYSTEM switch in OFF position.
Observe that blower motor starts when FAN switch is placed
in ON position and shuts down when FAN switch is placed
in AUTO position.
2. Place SYSTEM switch in COOL position and FAN switch
in AUTO position. Set cooling control below room
temperature. Observe that compressor, condenser fan, and
evaporator blower motors start. Observe that cooling cycle
shuts down when control setting is satisfied. The evaporator
fan will continue to run for 30 sec.
3. When using an auto--changeover room thermostat, place
both SYSTEM and FAN switches in AUTO positions.
Observe that unit operates in Heating mode when
temperature control is set to call for heating (above room
temperature) and operates in Cooling mode when
temperature control is set to call for cooling (below room
temperature).
IMPORTANT: Three--phase, scroll compressors are direction
oriented. Unit must be checked to ensure proper compressor
3--phase power lead orientation. If not corrected within 5 minutes,
the internal protector will shut off the compressor. The 3--phase
power leads to the unit must be reversed to correct rotation. When
turning backwards, the difference between compressor suction and
discharge pressures may be dramatically lower than normal.
CHECKING AND ADJUSTING REFRIGERANT CHARGE
UNIT DAMAGE HAZARD
Failure to follow this caution may result in unit damage.
When evaluating the refrigerant charge, an indicated
adjustment to the specified factory charge must always be very
minimal. If a substantial adjustment is indicated, an abnormal
condition exists somewhere in the cooling system, such as
insufficient airflow across either coil or both coils.
!CAUTION
The refrigerant system is fully charged with R--22 refrigerant and
is tested and factory sealed. Allow system to operate a minimum of
15 minutes before checking or adjusting charge.
NOTE: Adjustment of the refrigerant charge is not required unless
the unit is suspected of not having the proper R--22 charge.
A refrigerant charging label is attached to the outside of the service
access door. Thecharging labeland thetablesshownreferto system
temperatures and pressures in cooling mode only.
018 Model Only
The charging chart (see Table 6) includes the required liquid line
temperature at given discharge line pressures and outdoor ambient
temperatures.
An accurate subcooling thermocouple or thermistor--type
thermometer and a gauge manifold are required when using the
subcooling charging method for evaluating the unit charge. Do not
use mercury or small dial--type thermometers because they are not
adequate for this type of measurement.
Proceed as follows:
1. Remove caps from low-- and high--pressure service fittings.
2. Using hoses with valve core depressors, attach low-- and
high--pressure gauge hoses to low-- and high--pressure
service fittings, respectively.
3. Start unit in Cooling Mode and let unit run until system
pressures stabilize.
4. Measure and record the following:
a. Outdoor ambient--air temperature (°F(°C)db).
b. Liquid line temperature (°F(°C).
c. Discharge (high--side) pressure (psig).
5. Using “Cooling Charging Charts,” compare outdoor--air
temperature (°F(°C) db) with the discharge line pressure
(psig) to determine desired system operating liquid line
temperature (See Table 6).
6. Compare actual liquid line temperature with desired liquid
line temperature. Using a tolerance of ±2°F, (±1.1°C) add
refrigerant if actual temperature is more than 2°F(1.1°C)
higher than proper liquid line temperature, or remove
refrigerant if actual temperature is more than 2°F(1.1°C)
lower than required liquid line temperature.
48SD

19
024 through 060 Models
The charging chart (see Table 6A) includes the required suction
linetemperatureatgiven suction linepressuresand outdoorambient
temperatures.
An accurate superheat thermocouple or thermistor--type
thermometer and a gauge manifold are required when using the
superheat charging method for evaluating the unit charge. Do not
use mercury or small dial--type thermometers because they are not
adequate for this type of measurement.
Proceed as follows:
1. Remove caps from low-- and high--pressure service fittings.
2. Using hoses with valve core depressors, attach low-- and
high--pressure gauge hoses to low-- and high--pressure
service fittings, respectively.
3. Start unit in Cooling Mode and let unit run until system
pressures stabilize.
4. Measure and record the following:
a. Outdoor ambient--air temperature (°F(°C)db).
b. Evaporator inlet--air temperature (°F(°C) wb.
c. Suction--tube temperature (°F(°C) at low--side service
fitting.
d. Suction (low--side) pressure (psig).
5. Using “Cooling Charging Charts,” compare outdoor--air
temperature(°F(°C) db) with the suction line pressure (psig)
to determine desired system operating suction line
temperature. (See Fig. Table 6A.)
6. Compare actual suction--tube temperature with desired
suction--tube temperature. Using a tolerance of ±3°F
(±1.7°C), add refrigerant if actual temperature is more than
3°F(1.7°C) higher than proper suction--tube temperature,
or remove refrigerant if actual temperature is more than 3°F
(1.7°C) lower than required liquid line temperature.
NOTE: If the problem causing the inaccurate readings is a
refrigerant leak, refer to the Check for Refrigerant Leaks section.
INDOOR AIRFLOW AND AIRFLOW ADJUSTMENTS
UNIT OPERATION HAZARD
Failure to follow this caution may result in unit damage.
For cooling operation, the recommended airflow is350 to 450
cfm for each 12,000 Btuh of rated cooling capacity. For
heating operation, the airflow must produce a temperature rise
that falls within the range stamped on the unit rating plate.
CAUTION
!
Table 8 shows the temperature rise in each heating mode. Refer to
these tables to determine the desired heating airflow for the system
being installed. (See Table 7 for filter pressure drop and Table 9 for
wet coil pressure drop).
NOTE: Be sure that all supply--and return--air grilles are open, free
from obstructions, and adjusted properly.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Disconnect electrical power to the unit and install lockout tag
before changing blower speed.
!WARNING
Airflow can be changed by changing the lead connections of the
blower motor.
All 48SD units are factor wired for low speed except the 030
through the 048 size.
For color coding on the motor leads, see Table 5.
Table 5—Color Coding for Motor Leads
Black = High Speed
Blue = Medium Speed
Red = Low Speed
To change the speed of the indoor fan motor (IFM), remove the fan
motor speed leg lead from the blower relay (BR). This wire is
attached to terminal blower motor (BM) of the integrated gas control
(IGC) board for single--phase units. To change the speed, remove
and replace with lead for desired blower motor speed. Insulate the
removed lead to avoid contact with chassis parts.
COOLING SEQUENCE OF OPERATION
With the room thermostat SYSTEM switch in the COOL position
and the FAN switch in the AUTO position, the cooling sequence of
operation is as follows:
1. When the room temperature rises to a point that is slightly
above the cooling control setting of the thermostat, the
thermostat completes the circuit between thermostat
terminal R to terminals Y and G.
2. The normally open contactsof energized contactor (C) close
and complete thecircuit through compressor motor (COMP)
to condenser (outdoor) fan motor (OFM). Both motors start
instantly.
3. The set of normally open contacts of energized relay BM
close and complete the circuit through evaporator blower
(indoor) fan motor (IFM).
NOTE: Once the compressor has started and then stopped, it should
not be started again until 5 minutes have elapsed. The cooling cycle
remains on until the room temperature drops to a point that is
slightly below the cooling control setting of the room thermostat. At
this point, the thermostat breaks the circuit between thermostat
terminal R to terminals Y and G. These open circuits deenergize
contactor coil C. The condenser and compressor motors stop. After
a 30--sec. delay, the blower motor stops. The unit is in a standby
condition, waiting for the next call for cooling from the room
thermostat.
48SD

20
Table 6—Cooling Charging Chart -- 018 only
Required Subcooling oF(
oC) Required Liquid Line Temperature for a Specific Subcooling (R---22)
Model
Size Outdoor Ambient Temperature Required Subcooling (oF) Required Subcooling (oC)
75 (24) 85 (29) 95 (35) 105 (41) 115 (46) Pressure
(psig) 510 15 20 Pressure (kPa) 3 6 8 11
018 12 ( 6.7 ) 12 ( 6.7 ) 12 ( 6.7 ) 12 ( 6.7 ) 12 ( 6.7 ) 134 71 66 61 56 924 22 19 16 13
141 74 69 64 59 972 23 21 18 15
148 77 72 67 62 1020 25 22 19 17
156 80 75 70 65 1076 27 24 21 18
163 83 78 73 68 1124 28 26 23 20
171 86 81 76 71 1179 30 27 24 22
179 89 84 79 74 1234 32 29 26 23
187 92 87 82 77 1289 33 31 28 25
196 95 90 85 80 1351 35 32 29 27
205 98 93 88 83 1413 37 34 31 28
214 101 96 91 86 1475 38 36 33 30
223 104 99 94 89 1538 40 37 34 32
233 107 102 97 92 1606 42 39 36 33
243 110 105 100 95 1675 43 41 38 35
253 113 108 103 98 1744 45 42 39 37
264 116 111 106 101 1820 47 44 41 38
274 119 114 109 104 1889 48 46 43 40
285 122 117 112 107 1965 50 47 44 42
297 125 120 115 110 2048 52 49 46 43
309 128 123 118 113 2130 53 51 48 45
321 131 126 121 116 2213 55 52 49 47
331 134 129 124 119 2282 57 54 51 48
346 137 132 127 122 2386 58 56 53 50
359 140 135 130 125 2475 60 57 54 52
Table 6A—Cooling Charging Chart -- 024 through 060 only
A05109v2
Table 7—Filter Pressure Drop Table (in. wc)
FILTER SIZE in.
(mm)
CFM
500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300
20X20X1
(508X508X25) 0.05 0.07 0.08 0.1 0.12 0.13 0.14 0.15 ———————————
24X30X1
(610X762X25) ———0.04 0.05 0.06 0.07 0.07 0.08 0.09 0.1 ————————
24X36X1
(610X914X24) ———————0.06 0.07 0.07 0.08 0.09 0.09 0.10 0.11 0.12 0.13 0.14 0.14
48SD