Unitary products group G8C User manual

INSTALLATION
INSTRUCTIONS
CAUTION: READ ALL SAFETY GUIDES BEFORE YOU
START TO INSTALL YOUR FURNACE.
SAVE THIS MANUAL
EFFICIENCY
RATING
CERTIFIED
®
80% OUTDOOR
AUTOMATIC
IGNITION FURNACES
MODELS: G8C
50 THUR 125 MBH OUTPUT
035-15881-402 REV. A (1199) 650.67-N2V
GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
BLOWER PERFORMANCE FOR SMALL CHASSIS
OUTDOOR FURNACES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
BLOWER PERFORMANCE FOR LARGE CHASSIS
OUTDOOR FURNACES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
PRE-INSTALLATION INSPECTION . . . . . . . . . . . . . . . . . . . . . . . 3
CODE COMPLIANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
FURNACE LOCATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
CLEARANCE TO COMBUSTIBLE MATERIALS . . . . . . . . . . . 4
OUTSIDE SLAB INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . 4
COMBUSTION AND VENTILATION AIR . . . . . . . . . . . . . . . . . . . 4
INSTALLATION OF EXHAUST AND INTAKE-AIR HOOD
ASSEMBLIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
FURNACE SIZING AND DUCT SYSTEM DESIGN . . . . . . . . . . . 5
A/C USAGE DUCT SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . 6
RETURN AIR, FILTERS, AND DUCT CONNECTIONS . . . . . . . . 6
RETURN AIR TEMPERATURE . . . . . . . . . . . . . . . . . . . . . . . . 6
FILTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
DUCT CONNECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
GAS PIPING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
ELECTRICAL WIRING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
SERVICE WIRING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
ELECTRICAL GROUNDING . . . . . . . . . . . . . . . . . . . . . . . . . . 9
CONTROL WIRING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
HEAT ANTICIPATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
BLOWER MOTOR SPEED SELECTION . . . . . . . . . . . . . . . . . 9
MOTOR TERMINAL IDENTIFICATION . . . . . . . . . . . . . . . . . 10
BLOWER TIMINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
PRE-OPERATIONAL CHECKS . . . . . . . . . . . . . . . . . . . . . . . . . 12
SEQUENCE OF OPERATION. . . . . . . . . . . . . . . . . . . . . . . . . . . 12
FURNACE OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
OPERATING INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . 13
GAS SHUTOFF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
INSTALLATION CHECKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
CHECKING GAS INPUT RATE . . . . . . . . . . . . . . . . . . . . . . . 13
HIGH ALTITUDE ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . 13
HOW TO DETERMINE GAS INPUT RATE . . . . . . . . . . . . . . . . 14
CONVERSION INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . 14
MINOR INPUT ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . 14
MEASURING AIR TEMPERATURE RISE . . . . . . . . . . . . . . . 14
BLOWER REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

650.67-N2V 035-15881-402 REV. A (1199)
2Unitary Products Group
GENERAL INFORMATION
IMPORTANT - These instructions are for the use of
qualified individuals specially trained and experienced in
installation of this type equipment and related system compo-
nents.
Installation and service personnel are required by some
states to be licensed.
Persons not qualified shall not install this equipment nor inter-
pret these instructions.
NOTE: The words "shall" or "must" indicate a requirement
which is essential to satisfactory and safe perfor-
mance.
The words "should" or "may" indicate a recommen-
dation or advice which is not essential and not
required but which may be useful or helpful.
NOTE: After installing the furnace, show the user how to
turn off the electrical power and gas supply to the
furnace. Make sure that the user understands the
importance of following all safety rules.
SPECIFICATIONS
*BLOWER PERFORMANCE FOR SMALL CHASSIS OUTDOOR FURNACES
*BLOWER PERFORMANCE FOR LARGE CHASSIS OUTDOOR FURNACES
* See Figure 1 to determine chassis size.
*CHASSIS SIZE BTUH INPUT BLOWER
WHEEL SIZE
TEMPERATURE
RISE ºF
CFM HIGH @
0.5” W.C.
MAX. OUTLET
TEMPERATURE ºF MOTOR HP
Small Large
X 50,000 10” x 7” 30-60 1400 160 1/2
X 75,000 10” x 7” 35-65 1400 165 1/2
X 100,000 10” x 7” 45-75 1400 175 1/2
X 75,000 12” x 12” 30-60 2070 160 3/4
X 100,000 12” x 12” 35-65 2070 165 3/4
X 125,000 12” x 12” 40-70 2070 170 3/4
FACTORY EQUIPPED STANDARD BLOWERS
STANDARD CFM AT EXTERNAL STATIC PRESSURE
Blower Speed .1 .2 .3 .4 .5 .6 .7 .8
HIGH 1612 1560 1508 1453 1400 1330 1261 1186
MEDIUM 1303 1281 1258 1226 1195 1147 1100 1035
LOW 788 786 785 774 763 738 712 668
FACTORY EQUIPPED STANDARD BLOWERS
STANDARD CFM AT EXTERNAL STATIC PRESSURE
Blower Speed .1 .2 .3 .4 .5 .6 .7 .8
HIGH 2300 2250 2210 2140 2070 2030 1945 1775
MEDIUM HIGH 1660 1645 1620 1605 1585 1515 1480 1360
MEDIUM LOW 1440 1420 1385 1375 1360 1305 1280 1210
LOW 1265 1250 1240 1235 1200 1190 1135 1050

035-15881-402 REV. A (1199) 650.67-N2V
Unitary Products Group 3
PRE-INSTALLATION INSPECTION
Inspect the shipping container and furnace for any evidence
of shipping damage. If furnace damage is found, notify freight
carrier and file claim.
CODE COMPLIANCE
The furnace described in these instructions is Design Certi-
fied by the American Gas Association to be in compliance
with the latest edition of American National Standard Z21.47.
In Canada, these furnaces are Design Certified by the Cana-
dian Gas Association to be in compliance with the latest edi-
tion of CAN/CGA2.3. (See Figure 1.)
These furnaces are of the forced air type and are to be
installed out of doors only. They are acceptable for either
buildings constructed on site, modular, or manufactured
(mobile) homes by following the proper codes.
For site-built homes: This furnace must be installed in
accordance with these instructions, and local or state code.
In the absence of local codes, follow the latest edition of the
standard NATIONAL FUEL GAS CODE - ANSI Z223.1, AND
NATIONAL ELECTRICAL CODE, ANSI/NFPA 70 and/or
CAN/CGA B149 INSTALLATION CODES when in Canada.
For manufactured (mobile) homes: This furnace must be
installed in accordance with these instructions, and the MAN-
UFACTURED HOME CONSTRUCTION AND SAFETY
STANDARD, TITLE 24CFR, PART 3280 or, when such stan-
dard is not applicable, the STANDARD FOR MANUFAC-
TURED HOME INSTALLATION (Manufactured Home Sites,
Communities, and Set-Ups), ANSIA225.1, or the CAN/CSA-
Z240 MH, Series M86 Canadian Standard for Mobile Homes.
It is important to consult your local code authorities before
installation is made. The manufacturer assumes no responsi-
bility for equipment installed in violation of any code or regu-
lation.
FURNACE LOCATION
This furnace is Design Certified for outdoor installation only,
and can be mounted on a slab or roof top. They are suitable
for manufactured (mobile) homes when used with a slab only.
They are not to be installed within any part of a structure such
as an attic, crawl space, closet, etc.
The unit may be installed directly on wood flooring or on class
A, B, or C roof covering materials.
FIGURE 1 : FURNACE DIMENSIONS
W
L
C
B
A
D
H
SIDE
BACK SIDE
CHASSIS SIZE
LETTER SMALL LARGE
A
B
C
D
H
W
L
18”
12”
18”
25-5/8”
27-3/16”
23-3/8”
45-3/32”
22”
14”
24”
29-7/16”
31”
25”
48”
DO NOT make any flue or chimney connections to
this unit other than the factory provided exhaust
and air inlet hood assemblies. DO NOT vent the
flue outlet underneath any structure. The flue out-
let must not discharge less than two feet away
from any window or door, and must also not dis-
charge less than three feet from any motor-driven
air intake discharging into habitable areas. The
flue outlet and combustion air inlet must not be
blocked or closed for any reason.

650.67-N2V 035-15881-402 REV. A (1199)
4Unitary Products Group
CLEARANCE TO COMBUSTIBLE MATERIALS
Proper clearances from the furnace to any combustible mate-
rials must be maintained. These required minimum clear-
ances are shown below and on a label in the furnace.
Minimum Clearances:
Duct Side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 inches
Back: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 inches
Sides: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 inches
Top: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 inches
Bottom. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 inches
In Canada, it is recommended that the outlet duct be pro-
vided with a removable access panel. This opening shall be
accessible when the furnace is installed in service, and shall
allow the observance of smoke or reflected light inside the
casing to indicate the presence of leaks in the heat
exchanger. The removable access panel when installed, shall
provide an adequate seal.
OUTSIDE SLAB INSTALLATION
1. Select a location where water drainage cannot collect
around the unit.
2. Provide a level slab extending at least 1" beyond all four
sides of the furnace, and air conditioner (if provided as a
system). The slab should be at least 3-5" thick and
should be isolated from the foundation wall.
3. The location of the unit should be such as to provide
proper access for inspection, servicing and clearance
from combustibles.
Provide sufficient space around and in front of the furnace for
service and cleaning. Allow a minimum of 36 inches from the
sides of the furnace for service clearance.
COMBUSTION AND VENTILATION AIR
INSTALLATION OF EXHAUST AND INTAKE-AIR
HOOD ASSEMBLIES
1. Remove the paper wrapped exhaust hood and intake air
hood from the heat exchanger compartment. Also locate
the envelope containing eleven #10 sheet metal screws
needed for the installation. (See Figure 2.)
2. Use four of the screws to attach the exhaust hood
assembly to the cabinet, and the remaining seven to
attach the intake air hood. (See Figure 2.)
IMPORTANT - This furnace is not to be used as a con-
struction heater to supply heat to an unfinished building dur-
ing the finishing phases of construction. This practice
exposes the furnace to abnormally low return air tempera-
tures which can cause condensation in the furnace or vent
leading to premature failure. This practice also exposes the
furnace to an abnormally corrosive atmosphere from sources
such as paint, varnish and adhesives, which can lead to pre-
mature heat exchanger or vent failure.
The practice also allows foreign materials such as sawdust or
sheetrock dust to enter the furnace blower, burner, heat
exchanger, motors, and vent system resulting in shorter life of
the furnace. Use of this furnace as a construction heater will
void the warranty.
Failure to maintain proper clearances to combusti-
ble materials can cause a fire, which could result
in damage, death or personal injury.
Adequate ventilation and combustion air must be
provided to insure satisfactory and safe operation
of the furnace. DO NOT make any flue or chimney
connections to this unit other than the factory pro-
vided exhaust and air inlet hood assemblies. DO
NOT vent the flue outlet underneath any structure.
The flue outlet and combustion air inlet must not
be blocked or closed for any reason. Failure to
observe the recommendation could result in
asphyxiation.
DO NOT store or use halogen emitting substances
in the vicinity of this appliance. Such substances
include chlorine based cleaners and swimming
pool chemicals, water softening chemicals, de-
icing salts and chemicals, cleaning solvents such
as carbon tetrachloride or perchloroethylene, halo-
gen type refrigerants, printing inks, paint and paint
removers, varnishes, hydrochloric acid, cements
and glues, and masonry acid washing materials.
the air used by the burner for combustion must be
free of halogens to avoid possible corrosion to the
heating surfaces which could result in asphyxiation.

035-15881-402 REV. A (1199) 650.67-N2V
Unitary Products Group 5
FURNACE SIZING AND DUCT SYSTEM
DESIGN
The duct system must be installed in conformance with
ASHRAE/NFPA 90, Standard for Installation of Warm Air
Heating and Air Systems and other applicable local codes.
Failure to adhere to proper duct system design standards can
reduce airflow, resulting in reduced system performance and
possible furnace damage.
Consideration should be given to the heating capacity
required and also the air quantity (CFM) required if A/C is to
be installed along with the furnace or at some future time.
These factors can be determined by calculating the heat loss
and heat gain of the home or structure.
If these calculations are not performed and the furnace is
oversized, the following may result:
1. Short cycling of the furnace.
2. Wide temperature fluctuations from the thermostat set-
ting.
3. Reduced overall operating efficiency of the furnace.
The supply and return duct system must be of adequate size
and designed such that the furnace will operate within the
designed air temperature rise range and not exceed the max-
imum designed static pressure. These values are listed in
Table 1:
Additional information, values and data necessary for heat
loss, heat gain and duct system design may be found in
ASHRAE HANDBOOK OF FUNDAMENTALS-1993 EDITION
or in other nationally recognized publications recognized by
municipal, state, provincial and federal code authorities.
FIGURE 2 : EXTERNAL VIEW OF FURNACE WITH VENT HOOD ASSEMBLY
EXHAUST HOOD
ASSEMBLY
#10 x 3/8
SCREW x4
#10 x 3/8
SCREW x7
INTAKE
AIR HOOD
Table 1: STATIC PRESSURE
INPUT
BTUH
EXT. STATIC W.C.
MINIMUM MAXIMUM
50,000 .10 .50
75,000 3.12 .50
100,000 .15 .50
125,000 .20 .50
The return air system must be designed and
installed so that negative pressure created by the
air circulating fan cannot affect another appli-
ance’s combustion air supply (such as a water
heater), or act to mix products of combustion with
circulating air.

650.67-N2V 035-15881-402 REV. A (1199)
6Unitary Products Group
It is recommended that the supply air duct attached to the fur-
nace be provided with a removable access panel. The open-
ing should be accessible when the furnace is installed in
service and should be large enough that smoke or reflected
light may be observed inside the casing to indicate the pres-
ence of leaks in the heat exchanger. The cover panel for this
opening should be attached in such a manner as to prevent
leaks.
A/C USAGE DUCT SYSTEM
1. When a single (common) duct system is used one of the
following methods shall be used:
a. The optional cooling coil designed for slide-in instal-
lation with this furnace,
b. A self-contained A/C unit must be in parallel with
and isolated from the furnace.
2. If two duct systems are used as could be the case with a
coil-blower or a self-contained A/C unit, the furnace and
A/C unit should be controlled by a single combination
heating and cooling thermostat which will prevent the fur-
nace and A/C unit from operating simultaneously.
RETURN AIR, FILTERS, AND DUCT
CONNECTIONS
RETURN AIR TEMPERATURE
This furnace is designed to be operated in normal household
temperatures. The continuous return air temperature must
not be below 60 ºF or above 85 ºF.
FILTERS
Air filters of adequate size must be used with the return air
supply to this furnace. Failure to do so will cause dirt to accu-
mulate on the furnace blower motor, blower wheel, heat
exchanger and air conditioner coil, resulting in reduced sys-
tem efficiency, erratic control performance, and possible
equipment damage.
Filters are to be mounted at least one inch upstream from the
return connection to the unit. Locating the filter in a crawl
space, attic, or other inaccessible location will result in filters
not being changed as frequently as recommended.
Size filters according to the requirements in Table 2.
DUCT CONNECTIONS
Although these units have been specifically designed for
quiet, vibration free operation, air ducts can act as sounding
boards and could, if poorly installed, amplify the slightest
vibration to the annoyance level.
Where the unit is located adjacent to the living area, the sys-
tem should be carefully designed with cold air strategically
located to minimize transmission through the return air grille.
Although this year-round air conditioner is designed with a
large blower operating at moderate speed, any blower mov-
ing a high volume of air will produce audible noise which
could be objectionable when the unit is located very close to
a living area. It is often advisable to carry the return air ducts
under the floor or through the attic. Such design permits the
installation of air return remote from the living area (i.e., cen-
tral hall).
When installing duct outdoors where it will be exposed to
weather, care must be taken to completely weatherproof both
ducts and insulation. Take any additional measures, such as
flashings and caulking compound, necessary to provide a
good weather seal.
Dampers must be installed when a coil blower or
self-contained cooling unit is employed to prevent
conditioned cool air from coming in contact with
the heat exchanger to avoid moisture condensa-
tion and oxidation (rust), which could allow prod-
ucts of combustion to be circulated into the living
area by the furnace blower resulting in possible
asphyxiation. If dampers are the manually oper-
ated type, a means must be provided to prevent
either the furnace or the A/C unit from operating
(unless dampers are in full heat or cool position).
If a separate heating and separate cooling thermo-
stat is used, a manually operated electrical inter-
lock switch must be installed to prevent
simultaneous operation of both systems and avoid
a possible hazardous condition due to overheating
of the conditioned space.
Table 2: FILTER REQUIREMENTS CHART
HEAT INPUT
(BTU/HR)
COOLING
TONS
(NOMINAL
RECOMMENDED MIN.
FILTER AREA:
Washable Type Disposable
Type
50,000-75,000 2.0-2.5 290 480
50,000-100,000 3-3.5 405 675
100,000-
125,000 4 460 765
125,000 5 580 965

035-15881-402 REV. A (1199) 650.67-N2V
Unitary Products Group 7
GAS PIPING
Before installing gas piping, check with local code authorities
for requirements concerning gas piping.
In the absence of local codes, follow the recommendations
contained in NATIONAL FUEL GAS CODE ANSI Z223.1 for
gas piping materials, pipe sizing, and the requirements for
installation. In Canada, refer to the latest edition of the CAN/
CGA-B149 Installation Code and local codes for specifics. It
is recommended that a gas cock shutoff valve be installed in
the gas supply line outside the casing where it is readily
accessible, as close to the furnace as is practical, as shown
in Figure 3.
An 1/8 in. NPT (plugged) pressure tap for test gauge connec-
tion must be installed in the gas supply line immediately
upstream from the furnace if local authorities do not allow use
of the pressure tap in the gas valve for this purpose.
Install a dirt leg at the bottom of any vertical riser or drop, as
close to the furnace as possible, to collect moisture and for-
eign material. Install a ground joint union just ahead of the
gas control valve. A typical arrangement is shown in Figure 3.
Unless prohibited by local codes, it is permissible to use a
flexible corrugated metal gas connector for the last section of
gas piping connected to the furnace gas valve. If a flexible
connector is used, it must be certified to be in compliance
with ANSI Standard Z21.24 or, in Canada, with Standard
CAN1-6.10. When making the connection at the gas control
valve, use a wrench on the inlet side of the valve to prevent
any possible twisting of the valve body which could cause
damage and leaks. When making up pipe joints use pipe
thread compound which is resistant to natural and LP (pro-
pane) gases.
Following installation of the piping, first ensure that the gas
control knob on the gas valve is in the off position and then
pressurize the system with gas. Thoroughly check the piping
system for leaks.
Use only the type of gas for which the furnace is
equipped. Using the wrong gas could create a
hazard, resulting in damage, personal injury or
death.
FIGURE 3 : OUTDOOR FURNACE: BURNER COMPARTMENT AND BLOWER ASSEMBLIES
ROLL-OUT SWITCH
FLAME
SENSOR
ALTERNATE
GAS PIPE
ROUTING
GAS SHUTOFF
DRIP LEG
GAS VALVE
BURNER
MANIFOLD
BURNERS
IGNITOR
LIMIT SWITCH
GROUND
JOINT UNION
PRESSURE SWITCH
PRIMARY
GAS PIPE
ROUTING
EXHAUST DUCT
INDUCER BLOWER
INTEGRATED
CONTROL BOARD
5 AMP. AUTOMATIC TYPE
CONTROL TRANSFORMER
LINE VOLTAGE
TERMINAL BLOCK
LOW VOLTAGE BOX
BLOWER MOTOR
CAPACITOR LIMIT SWITCH
BLOWER
ASSEMBLY
BLOWER
ASSEMBLY

650.67-N2V 035-15881-402 REV. A (1199)
8Unitary Products Group
The maximum and minimum gas supply pressure required at
the inlet of the gas control valve is shown on the unit rating
plate. When the furnace is in operation, the inlet pressure
must be within the limits shown.
ELECTRICAL WIRING
All internal wiring has been made at the factory. Field wiring
requires only the connection of the line voltage supply wiring,
and low voltage thermostat wiring.
Line voltage supply wiring and control wiring may be brought
into the furnace through either side using the holes provided.
The furnace has been provided with two holes for line voltage
wiring, and one hole for thermostat wiring on each side. The
line voltage wiring plates may be removed, or removed and
reinstalled for different conduit sizes. (See Figures 4 and 5.)
During pressure testing of the gas supply piping
system, observe the following to avoid fire, explo-
sion, asphyxiation, or damage to the appliance.
If test pressure is greater than 1/2 psig (3.48
kPa)(14" w.c.), the furnace and its individual shut-
off valve must be disconnected from the gas sup-
ply system.
Never use an open flame to check for leaks. Fire
or explosion could occur. Since some leak solu-
tions including soap and water may cause corro-
sion or stress cracking, the piping must be rinsed
with water after testing unless it has been deter-
mined that the leak solutions is noncorrosive.
FIGURE 4 : BASE MODEL FRONT VIEW
A
B
C
DE3
9
16
1
5
8
7
8
D
1
3
32
D
SMALL LARGE LETTER
A
B
C
D
E
2-1/8”
2-1/8”
2-1/4”
2-31/32”
1-9/16”
1-3/4”
2-1/8”
1-3/4”
4-1/8”
1-9/16”
LINE VOLTAGE
SUPPLY INLETS
7/8 DIA. LOW VOLTAGE
INLET HOLE

035-15881-402 REV. A (1199) 650.67-N2V
Unitary Products Group 9
SERVICE WIRING
Field wiring connections should be made inside the control
box and a suitable strain relief should be used at the point the
wires exit the furnace casing. In order for the electrical con-
trols in the furnace to operate properly, correct electrical
polarity must be observed. Field wiring of the unit should con-
form to local codes or in the absence of local codes with the
National Electrical Code ANSI/NFPA 70. In Canada, field wir-
ing of the unit should conform to local codes or in the
absence of local codes with the Canadian Electrical Code,
Part I, CSA C22.1.
A separate fused circuit from the main electrical panel should
serve only the furnace.
ELECTRICAL GROUNDING
The furnace casing must have an uninterrupted electrical
ground in accordance with the National Electrical Code ANSI/
NFPA 70 or, in Canada, with the Canadian Electrical Code,
Part I, CSA C22.1. DO NOT use gas piping as an electrical
ground.
CONTROL WIRING
The thermostat should be installed in accordance with the
manufacturer's instructions, furnished with the thermostat,
and make connections to the unit as shown on the unit wiring
diagram. It is recommended that size 18 AWG wire be used.
HEAT ANTICIPATOR
If the wall thermostat has an adjustable heat anticipator, the
setting should be.48 amps. If any accessories are to be con-
nected to the furnace, the heat anticipator setting may
change. Use a suitable ammeter to measure the actual antic-
ipator current.
BLOWER MOTOR SPEED SELECTION
These furnaces are equipped with blowers which have multi-
speed direct drive motors.
The blower speed selected is dependent upon the design
and static pressure loss of the duct system. The duct system
external static pressure includes the combined total of the
supply and return ducts and any air conditioning coil if used.
The furnace must be adjusted to operate at or below the
maximum external static (in. W.C.) and within the air temper-
ature rise range as shown on the unit rating plate and in the
specification table.
Dependent upon the conditions in a particular installation, the
blower speeds may need to be changed to give the proper
operation on cooling or heating.
FIGURE 5 : BASE MODEL REAR VIEW
F
G
H
J
F
H
G
JK
CHASSIS SIZE
LETTER SMALL LARGE
F
G
H
J
K
1-3/4”
3-3/4”
2-3/16”
1-9/16”
2-3/8”
3-1/32”
3-1/4”
1-7/32”
2-3/32”
----

650.67-N2V 035-15881-402 REV. A (1199)
10 Unitary Products Group
MOTOR TERMINAL IDENTIFICATION
Motor terminal wiring may be identified by using the following
color code breakdown.
These leads should be connected in the control box to either
the heating or cooling terminal, depending on the airflow
desired. The unused motor speed lead(s) should be con-
nected to the isolated terminals marked M1 park or M2 park
on the blower control board in the furnace control box. On
models with four speed motors using one speed for heating
and cooling an additional unused speed lead must be insu-
lated by installer using suitable means.
The electronic furnace control supplied on this furnace is
equipped with a diagnostic light which flashes when there is a
service problem with the furnace. The light can be viewed
through the view window in the burner compartment door.
The number of times the light flashes indicates where in the
furnace the problem is located, as listed in the Table 3.
BLOWER TIMINGS
The heating on delay, from when the gas valve opens to
when the circulating blower comes on, is fixed at 30 seconds
and is not adjustable.
The heating off delay, from when the gas valve closes to
when the circulating blower shuts off, is factory set at 150
seconds. This timing may be adjusted to 60, 90, 120 or 150
seconds.
The T. I. electronic furnace control has four pins and a small
jumper plug which is used to adjust the blower off delay. Push
the jumper plug on the two pins adjacent to the desired
blower delay time. (See Figure 6.)
SHOCK HAZARD - Be sure electrical power to
furnace is turned off before changing motor
speeds.
Three - Speed Motors: Four - Speed Motors:
Orange - Common
Black - High
Blue - Medium
Red - Low
Orange - Common
Black - High
Blue - Medium High
Yellow - Medium Low
Red - Low
Table 3: SERVICING TROUBLESHOOTING CHART - 115 VOLT MODELS
# OF DIAGNOSTIC FLASHES PROBLEM SYMPTOMS PROBABLE PROBLEM LOCATION(S)
Steady Off Normal operations
One (1) False flame sense Check for stuck open gas valve.
Two (2) Pressure switch stuck closed Check for shorted wires, bad pressure switch.
Three (3) Pressure switch failed to close Check vent blower, pressure switch, vent blockage, or
disconnected pressure hose.
Four (4) Limit switch open Check for open limit switch, loose connections in limit
circuit.
Five (5) Rollout switch open Check for open rollout switches, loose connections in
rollout switch circuit.
Six (6) One hour pressure switch lockout Pressure switch has cycled four times in a single call
for heat. Check for vent blockage, loose connections in
pressure switch circuit.
Seven (7) One hour ignition lockout Burner failed to light in three tries. Check gas flow, gas
pressure, gas valve operation, flame sensor.
Eight (8) One hour ignition lockout Five recycles in a single call for heat. Check gas flow,
gas pressure, gas valve operation, flame sensor.
Nine (9) Reversed line voltage polarity Check incoming power wiring for proper polarity.
Ten (10) No code
Eleven (11) Disconnected jumper on control Check and replace, if necessary, the jumper.
Steady on Gas valve energized with no call for heat from
thermostat.
Control failure or unit mis-wired.
FIGURE 6 : BLOWER TIMING CHANGE
120
150
60
PUT JUMPER PLUG ACROSS
PINS FOR DESIRED BLOWER
DELAY TIME (90 SECONDS

035-15881-402 REV. A (1199) 650.67-N2V
Unitary Products Group 11
WIRING DIAGRAM
FIGURE 7 : WIRING DIAGRAM - 115 VOLT MODELS
FACTORY WIRED HEATING AND COOLING SPEED IS SHOWN
ABOVE. FOR FIELD ADJUSTMENT OF BLOWER SPEED
REFER TO BLOWER PERFORMANCE DATA IN THE
INSTALLATION INSTRUCTIONS.
ALS - AUX. LIMIT SWITCH
CAP- CAPACITOR
FS - FLAME SENSOR
GV - GAS VALVE
IFC - FURNACE CONTROL
IGN - HOT SURFACE IGNITOR
LVB - LOW V OLTAG E BOX
PLS - PRI. LIMIT SWITCH
PS - PRESSURE SWITCH
ROS - ROLLOUT SWITCH
TB - TERMINAL BLOCK
T’STAT - WALL THERMOSTAT
VM - VENT MOTOR
1
STEADY OFF - NORMAL OPERATION
ONE FLASH - FALSE FLAME SENSE
TWO FLASHES - PRESSURE SWITCH STUCK CLOSED
THREE FLASHES - PRESSURE SWITCH FAILED TO CLOSE
FOUR FLASHES - LIMIT SWITCH OPEN
FIVE FLASHES - ROLLOUT SWITCH OPEN
SIX FLASHES - PRESSURE SWITCH CYCLE LOCKOUT
SEVEN FLASHES - IGNITION LOCKOUT DUE TO RETRIES
EIGHT FLASHES - IGNITION LOCKOUT DUE TO RECYCLES
NINE FLASHES - REVERSED LINE VOLTAGE POLARITY
TEN FLASHES - NO CODE
ELEVEN FLASHES - DISCONNECTED JUMPER ON CONTROL
STEADY ON - GAS VALVE ENERGIZED WITH “W” OFF
OR CONTROL VALVE FAILURE
BLOWER MOTOR
TERMINAL COLOR # OF
SPEEDS
CHASSIS
SIZE
COM
HIGH
MED
LOW
COM
HIGH
MED-HI
MED-LO
LOW
ORANGE
BLACK
BLUE
RED
ORANGE
BLACK
BLUE
YELLOW
RED
3
3
3
3
4
4
4
4
4
SMALL
SMALL
SMALL
SMALL
LARGE
LARGE
LARGE
LARGE
LARGE
FACTORY SET BLOWER SPEEDS
MODEL HEAT COOL # OF
SPEEDS
CHASSIS
SIZE
50K, 3 TON
75K, 3 TON
100K, 3 TON
75K, 5 TON
100K, 5 TON
125K, 5 TON
LOW
HIGH
HIGH
LOW
MED-HI
MED-HI
MED
MED
MED
MED-LO
MED-LO
MED-LO
3
3
3
4
4
4
SMALL
SMALL
SMALL
LARGE
LARGE
LARGE
115V
24V
P-GA
P-SA
P-11A
P-8A
P-7A
P-10A
P-3A
P-1A
P-9A
P-12A
XFRM
ROS
PS ALS PLS
FS
GV
NEUT.
P-2A
XFRM
L1
P-3B
P-1B
PA RK
PA RK
HEAT
COOL
P-4B
P-2B
IFC
VM
IGN BLOWER
COM
HI
MED-HI
MED-LO
LOW
CAP
GND. N
LI
1
FS
PLS
ALS
RED
PS
RS
TO
T’STAT LVB
RED
RED
YEL
GRY
GRY
XFRM
24V
115 V
BLK
WHT
BLK
PUR
BLU
PUR
BLU
PROBE
ROLL OUT
12
34
NEUTRALS
WHT
TB
BLK
HUM
EAC
XFRM
LI
PA RK
PA RK
HEAT
COOL
115V
YEL
WHT
RED
GRN
BLU
RED
ORG
RED
ORG
GRN
BRN
BRN
GV
GND.
IFC
1CAP
BLOWERCOM
HI
MED-HI
MED-LO
LO
ORG
BLK
BLU
YEL
RED
FACTORY WIRING
IF ANY OF THE ORIGINAL
WIRING SUPPLIED WITH
THIS UNIT MUST BE
REPLACED, IT MUST BE
REPLACED WITH TYPE 105º
DISCONNECT THE ELECTRIC POWER BEFORE SERVICING.
WARNING:
AVERTISSEMENT:
DECONNECTER DU CIRCUIT D’ALIMENTATION ELECTRIQUE AVANR L’ENTRETIEN
Y
W
R
G
C
10 11 12
789
456
123
IGN
VM

650.67-N2V 035-15881-402 REV. A (1199)
12 Unitary Products Group
PRE-OPERATIONAL CHECKS
1. Be sure that the furnace is equipped for the type of gas
being supplied to the furnace. See unit rating plate.
2. Manually spin circulating air blower wheel to ensure that
it turns freely and does not strike the blower housing.
3. Was the gas piping tested and/or purged of air then
checked for leaks? See instructions for gas piping. Even
the smallest leak must be eliminated before attempting
to light the furnace.
SEQUENCE OF OPERATION
These furnaces are equipped with an electric hot surface
burner ignition system. In response to a call for heat by the
room thermostat, the burners are lighted by a hot glowing
ignitor at the beginning of each operation cycle. The burners
will continue to operate until the thermostat is satisfied at
which time all burner flame is extinguished. During the off
cycle no gas is consumed. With the room thermostat set
below room temperature, and with the electrical power and
gas supply to the furnace on, the normal sequence of opera-
tion is as follows:
1. When the room temperature falls below the setting of the
room thermostat, the thermostat energizes the furnace
control board.
2. When the furnace control board is activated, the vent
blower is turned on. A circuit is also made through the
normally open pressure switch contacts.
3. As the vent blower increases in speed, the contacts of
the pressure switch will close and complete the electrical
circuit to the ignitor.
4. During the next 15 to 30 seconds, the vent blower will
bring fresh air into the heat exchanger and the ignitor will
begin to glow. At the end of this period, the gas valve will
open and the burners will light.
5. After the burners light, a separate probe acts as a flame
sensor to check for the presence of flame. As long as
flame is present, the system will monitor it and hold the
gas valve open.
6. If the burners fail to light within 6-8 seconds after the gas
valve opens, the gas valve will close and the ignitor will
be turned off. After a short pause, the system will recycle
and try again for ignition. If the burners fail to light after
three tries, the ignition system will lock out for one hour.
The system will remain in lock-out mode until the room
thermostat is cycled off then back on, or one hour has
elapsed, causing the furnace to try for ignition again.
7. The elapsed time from the moment the room thermostat
closes to when the burners light may be 20-35 seconds.
This delay is caused by (1) the time required for the vent
blower to come to full speed, (2) the time required for the
ignitor to heat up and (3) the time required for fresh air to
be brought into the heat exchanger.
8. About thirty seconds after the burners have lit, the fan
switch will close and the furnace air circulation blower
will run.
9. When room thermostat is satisfied the circuit to the fur-
nace control board is broken. The circuit to the vent
blower and the gas valve is broken and the burners are
extinguished. Then the furnace control board will keep
the circulating blower running for a period of time to allow
additional heat to be drawn from the heat exchanger.
FURNACE OPERATION
FOR YOUR SAFETY READ BEFORE OPERATING:
1. This appliance does not have a pilot. It is equipped for
the type of gas being supplied to the furnace. See unit
rating plate.
2. Before operating smell all around the appliance area for
gas. Be sure to smell next to the floor because some gas
is heavier than air and will settle on the floor.
WHAT TO DO IF YOU SMELL GAS:
• Do not try to light any appliance.
• Do not touch any electric switch; do not use any phone in
your building.
• Immediately call your gas supplier from a neighbor's
phone. Follow the gas supplier's instructions.
• If you cannot reach your gas supplier, call the fire depart-
ment.
3. Use only your hand to move the gas control knob. Never
use tools. If the knob will not move by hand, DON’T try to
repair it, call a qualified service technician. Force or
attempted repair may result in a fire or explosion.
4. DO NOT use this appliance if any part has been under
water. Immediately call a qualified service technician to
inspect the appliance and to replace any part of the con-
trol system and any gas control which has been under
water.
SHOCK HAZARD - Be sure electrical power to fur-
nace is turned off before performing the pre-opera-
tional checks.
IF YOU DO NOT FOLLOW THESE INSTRUC-
TIONS EXACTLY, A FIRE OR EXPLOSION MAY
RESULT CAUSING PROPERTY DAMAGE, PER-
SONAL INJURY OR LOSS OF LIFE.

035-15881-402 REV. A (1199) 650.67-N2V
Unitary Products Group 13
OPERATING INSTRUCTIONS
1. STOP! Read the safety information listed above.
2. Set the thermostat to the lowest setting, or OFF.
3. Turn off all electric power to the furnace.
4. This appliance does not have a pilot. It is equipped with
an ignition device which automatically lights the burners.
DO NOT try to light the burners by hand.
5. Remove Burner Compartment door panel.
6. Move gas valve control lever or knob to "OFF". See Fig-
ure 9.
7. Wait five (5) minutes to clear out any gas. Then smell for
gas, including near the floor. If you smell gas, STOP! Fol-
low "2" in the safety information above. If you don't smell
gas, go to the next step.
8. Move gas control lever or knob to "ON".
9. Replace Burner Compartment door panel.
10. Turn on all electric power to the furnace.
11. Set thermostat to desired setting.
GAS SHUTOFF
This furnace is equipped with a manual gas shutoff. Figure 9
shows the location of the manual shutoff valve. To turn off gas
to the furnace, move the lever or knob on the gas valve to the
"OFF" position. It may be necessary to depress the knob or
lever in order to move it to the "OFF" position.
The furnace installation should also have a manual shutoff
valve in the gas piping to the furnace, similar to what is
shown in Figure 8. To turn off the gas to the furnace, use a
wrench and turn the knob or lever so that it is pointing 90
degrees from the gas pipe, as shown in Figure 8.
INSTALLATION CHECKS
CHECKING GAS INPUT RATE
The maximum BTUH input capacity for each model is shown
on the furnace rating plate and in the specification table. This
input must not be exceeded.
The input shown may be used in geographic areas where the
elevation is from 0 to 2000 feet. The BTU input depends on
the calorific heating value of the gas, orifice size, and mani-
fold pressure. Orifice sizes are based on gas values of 1050
BTU/cu. ft. for natural gas and 2500 BTU/cu.ft. for LP (pro-
pane) gas. The orifice sizes supplied with the furnace should
provide satisfactory input capacity for installations in most
areas, except at high altitude.
HIGH ALTITUDE ADJUSTMENT
In areas above 2000 feet elevation, the furnace BTU input
must be reduced 4% for each 1000 feet of elevation above
sea level. For minor input adjustments, it is permissible to
adjust the manifold pressure at the gas valve pressure regu-
lator. Do not adjust the manifold pressure more than .3" w.c.
from the specified regulator settings (3.5" for natural gas and
10" for LP (propane) gas). In many cases, adjusting the gas
valve manifold pressure may not be enough to reduce the
gas input enough for high altitudes. In such cases, the gas
orifices must be changed to a smaller size. The chart below
shows the proper gas orifice to use at various altitudes for
either natural or LP (propane) gas.
FIGURE 8 : MANUAL GAS SHUTOFF VALVE
OFF ON
OFF ON
FIGURE 9 :
Natural gas heating values can vary widely. It is
the responsibility of the installer to make sure that
the input rate to the furnace as installed does not
exceed the nameplate rating of the furnace. Fail-
ure to do so can cause heat exchanger failure,
resulting in injury or death.
MANUAL GAS SWITCH
O
F
F
ON
1
3

650.67-N2V 035-15881-402 REV. A (1199)
14 Unitary Products Group
HOW TO DETERMINE GAS INPUT RATE
Where gas is metered, the input rate may be determined by
the following method:
Contact the gas supplier, public utility company or LP (pro-
pane) gas distributor to obtain the calorific gas value of the
gas being used. When checking the gas input rate, any other
gas burning appliances connected to the same meter should
be completely off. The furnace should be allowed to operate
for 5 minutes before attempting to check the gas input rate.
To check flow rate, observe the one cubic foot dial on the gas
meter and determine the number of seconds required for the
dial hand to complete one revolution (seconds to flow one
cubic foot.)
To determine the number of seconds per cubic foot that is
necessary to achieve the correct input rate, use the following
formula: GAS VALUE X 3600 !DESIRED INPUT = SEC-
ONDS NEEDED.
Example: 1000 BTU gas, furnace input 100,000 BTUH Sec-
onds for one cubic foot = 1000 X 3600 !100,000 = 36 sec-
onds.
If, when clocking the meter, the one cubic foot dial makes a
complete revolution in less time than was calculated that it
should, the furnace is overfired and should be derated. If it
takes more time for the meter to make one revolution than
was calculated, the furnace is underfired.
The orifice size must be changed to correct an overfired or
underfired condition. If it is determined that different orifices
are needed, please contact your distributor for assistance in
selecting the correct replacement.
CONVERSION INSTRUCTIONS
MODELS WITH CONVERTIBLE REGULATOR (SEE FIG-
URE 9): These furnaces are design certified for use with
either Natural or LP gas, and may be converted from one gas
to the other. Parts necessary for conversion are included with
the furnace. Instructions for making the conversion are
printed on a label inside the burner compartment access
panel, and on the rating plate.
MINOR INPUT ADJUSTMENT
The input may be adjusted slightly by adjusting the pressure
regulator setting in the gas valve in order to change the man-
ifold pressure.
MODELS WITH CONVERTIBLE REGULATOR (SEE FIG-
URE 9) USING NATURAL GAS: Remove the pressure regu-
lator converter with a 7/16" open end or boxed end wrench,
exposing the adjusting screw. Turn the screw counter-clock-
wise to decrease pressure, clockwise to increase pressure.
Remove the convertible regulator top portion, paying close
attention to install as removed, i.e., the arrow for the side
marked "NAT." must face the body of the valve.
USING LP (PROPANE) GAS: Remove the plastic dust cover
from the pressure regulator convertor. Using an Allen type
wrench, with the converter screwed snugly into the valve,
turn the set screw counter-clockwise to decrease pressure,
clockwise to increase pressure.
IMPORTANT - In no case should the final manifold pres-
sure vary more than ± .3" W.C. from the specified regulator
pressure settings (3.5" for Natural Gas and 10" for LP [Pro-
pane] Gas.)
MEASURING AIR TEMPERATURE RISE
For proper furnace operation, the air temperature rise must
be within the range shown on the furnace rating plate.
HIGH ALTITUDE GAS ORIFICES
ALTITUDE ABOVE SEA LEVEL IN FEET
GAS TYPE 0-2,000 2,000-4,500 4,500-8,000 8,000-9,000 9,000-10,000
NATURAL GAS #42 #43 #44 #45 #46
.093 .089 .086 .082 .081
LP GAS #54 #55 #55 #56 #56
.055 .052 .052 .046 .046
Never attempt to modify this furnace, fire,
explosion, or asphyxiation may result. If mal-
function is apparent, contact qualified service
agency and/or gas utility for assistance.
Operating the furnace outside of the proper air
temperature rise range may cause poor heating
performance and shorter heat exchanger life.

035-15881-402 REV. A (1199) 650.67-N2V
Unitary Products Group 15
1. Place thermometer in the supply air plenum about two
feet from the furnace outlet. If an air conditioning coil is
installed, the thermometer should be placed downstream
of the coil. The thermometer tip should be as near as
possible to the center of the plenum for proper measure-
ment.
2. Place thermometer in return air duct about two feet from
furnace, with the tip of thermometer as near as possible
to the center of he duct.
3. Set thermostat to highest temperature setting and allow
furnace to run for at least five minutes before checking
temperatures.
4. Calculate air temperature rise by subtracting supply air
temperature from the return air temperature.
5. If temperature rise is not within the range shown on the
furnace rating plate, the blower speed may need to be
changed.
6. If the blower speed is changed, recheck the temperature
rise by repeating steps 1 through 4 above.
7. If the air temperature rise is not within the proper range
even after changing blower speeds, check ductwork
design with a qualified heating engineer. It may be nec-
essary to re-size the ductwork.
8. Balance the System - The air distribution system should
be balanced, using in-line duct dampers, if employed, to
provide for satisfactory air delivery room to room. It is
recommended that dampers in registers not be used for
balancing the system.
BLOWER REMOVAL
Should the blower assembly require removal for any reason,
follow the procedure below: (See Figure 10.)
1. Remove blower access door.
2. Disconnect blower motor leads at motor terminal block,
and auxiliary limit switch leads from the switch mounted
on top of the blower housing.
3. Remove the two (2) sheet metal screws which connect
the triangular mounting bracket to the cabinet side.
4. Remove the sheet metal screws which attach the top
blower mounting flange to the blower bulkhead panel.
5. Lift the blower assembly up to clear the bottom offset
mounting bracket, and pull toward you to remove.
REPLACEMENT PARTS
If necessary, to replace any component part(s), it may be
obtained through an authorized dealer or the nearest distribu-
tor. If an authorized dealer does not have the part in stock, it
may be obtained directly from the company shown on the fur-
nace rating plate.
Following major service or replacement of functional parts it
is recommended that the furnace be operated in the various
modes to insure that performance is normal and control com-
ponents are functioning properly.
The parts listed below are only those that are functional parts
and those that might require replacement. The parts listed
are by part name (description) only and CODE reference
NUMBER. The CODE number is used to determine the loca-
tion of the part in the generalized, pictorial illustration pro-
vided. (See Figure 11.)
WHEN ORDERING PARTS - ORDER BY NAME AND
DESCRIPTION. DO NOT ORDER BY CODE NUMBER.
ALSO WHEN ORDERING PARTS please provide: (a) Com-
plete furnace Model Number and Serial Number. These may
be found on the rating plate located behind the upper front
panel (door) of the furnace. (b) Type of gas being used. (c) Is
furnace being used in conjunction with air conditioning or
heat pump?
SHOCK HAZARD - Be sure electrical power to
furnace is turned off before proceeding with blower
removal.
FIGURE 10 : BLOWER REMOVAL
Only genuine authorized replacement parts should
be used. Substitute parts should not be used as
they may not be the same in operational and
safety characteristics.
REMOVAL - LIFT
BLOWER UP AND
OUT OF BLOWER
BRACKET

Subject to change without notice. Printed in U.S.A. 035-15881-402 REV. A
Copyright © by Unitary Products Group 1999. All rights reserved. Supersedes: 035-15881-401(1098) 650.67-N2V (1199)
Unitary 5005 Norman
Product York OK
Group Drive 73069
1. TOP PANEL
2. EXHAUST DUCT
3. SENSOR ROD
4. VENT BLOWER
5. IGNITOR
6. LIMIT SWITCH
7. BLOWER BRACKET
8. SENSOR ROD
9. BLOWER MOTOR
10. BLOWER WHEEL
11. FURNACE CONTROL
12. BLOWER MOTOR HANGER
13. BLOWER LIMIT SWITCH
14. RUBBER MOTOR MOUNTS
15. TRANSFORMER
16. TERMINAL BLOCK
17. HEAT EXCHANGER
18. CAPACITOR
19. ROLLOUT SWITCH
20. BURNER
21. GAS VALVE
22. GAS ORIFICE
23. EXHAUST VENT HOOD
FIGURE 11 : REPAIR PARTS LISTING
BURNER ASSEMBLY
4-SECTION MODEL SHOWN
EXHAUST VENT
HOOD ASSEMBLY
TOP VIEW
BURNER COMPARTMENT VIEW
19
20 321
22
23
6
5
4
3
2
1
8
11
7
9
12
13
10
15
14
16
17
6
18