York FC8T-UH User manual

272312-UIM-A-0407
EFFICIENCY
RATING
CERTIFIED
ISO 9001
Certified Quality
Management System
HIGH EFFICIENCY
TUBULAR HEAT EXCHANGER SERIES
MODELS: PT8-UH / FC8T-UH / FL8T-UH / LC8T-UH / LL8T-UH
(Two Stage Upflow / Horizontal / LowNOx)
40 - 120 MBH INPUT
(11.72 - 35.17 kW) INPUT
INSTALLATION MANUAL
SECTION I: SAFETY
This is a safety alert symbol. When you see this symbol on
labels or in manuals, be alert to the potential for personal
injury.
Understand and pay particular attention to the signal words DANGER,
WARNING, or CAUTION.
DANGER indicates an imminently hazardous situation, which, if not
avoided, will result in death or serious injury.
WARNING indicates a potentially hazardous situation, which, if not
avoided, could result in death or serious injury.
CAUTION indicates a potentially hazardous situation, which, if not
avoided may result in minor or moderate injury. It is also used to
alert against unsafe practices and hazards involving only property dam-
age.
Improper installation may create a condition where the operation of
the product could cause personal injury or property damage.
Improper installation, adjustment, alteration, service or mainte-
nance can cause injury or property damage. Refer to this manual
for assistance or for additional information, consult a qualified con-
tractor, installer or service agency.
This product must be installed in strict compliance with the installa-
tion instructions and any applicable local, state, and national codes
including, but not limited to building, electrical, and mechanical
codes.
LIST OF SECTIONS
SAFETY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
DUCTWORK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
FILTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
GAS PIPING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
ELECTRICAL POWER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
VENT SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
SAFETY CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
START-UP AND ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . .22
WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
LIST OF FIGURES
Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Typical Attic Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Typical Suspended Furnace / Crawl Space Installation . . . . . . . . . . . . 7
Side Return Cutout Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Gas Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Upflow Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Horizontal Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Electrical Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Thermostat Chart - AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Thermostat Chart - HP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Accessory Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Twinning Wiring Diagram - 1H/1C Thermostat . . . . . . . . . . . . . . . . .15
Twinning Wiring Diagram - 2H/1C Thermostat . . . . . . . . . . . . . . . . .15
Twinning Wiring Diagram - 2H/2C Thermostat . . . . . . . . . . . . . . . . .15
Vent Termination 10 ft. (3.0 m) or less . . . . . . . . . . . . . . . . . . . . . . . . 15
Vent Termination more than 10 ft. (3.0 m) . . . . . . . . . . . . . . . . . . . . .16
Vent Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Typical Sidewall Vent Application . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Typical Sidewall Vent and Termination Configuration . . . . . . . . . . . .17
Home Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Combustion Airflow Path Through The Furnace
Casing to the Burner Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Alternate Air Intake, Air Outlet and Chimney Connections . . . . . . . . .19
Air Inlet, Outlet and Chimney Connections . . . . . . . . . . . . . . . . . . . . .19
Typical Chimney Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Horizontal Air Inlet, Outlet and Chimney Connections . . . . . . . . . . . .20
Outside and Ambient Combustion Air . . . . . . . . . . . . . . . . . . . . . . . . .20
Pressure Switch Tubing Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Gas Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Reading Gas Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Furnace Control Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
LIST OF TABLES
Unit Clearances to Combustibles (All Dimensions in Inches, and All
Surfaces Identified with the Unit in an Upflow Configuration) . . . . . . .4
Minimum Duct Sizing For Proper Airflow . . . . . . . . . . . . . . . . . . . . . . .5
Round Duct Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Cabinet and Duct Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Recommended Filter Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Nominal Manifold Pressure - High Fire . . . . . . . . . . . . . . . . . . . . . . . . 9
Nominal Manifold Pressure - Low Fire . . . . . . . . . . . . . . . . . . . . . . . . .9
Ratings & Physical / Electrical Data . . . . . . . . . . . . . . . . . . . . . . . . . .10
Roof Pitch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Estimated Free Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Free Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Unconfined Space Minimum Area in Square Inch . . . . . . . . . . . . . . .20
Inlet Gas Pressure Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Nominal Manifold Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Filter Performance - Pressure Drop Inches W.C. and (kPa) . . . . . . . .27
Field Installed Accessories - Non Electrical . . . . . . . . . . . . . . . . . . . .27
Blower Performance CFM - Upflow (without filter) - Bottom Return . .28
Blower Performance CFM - Upflow (without filter) - Left Side Return 29

272312-UIM-A-0407
2Unitary Products Group
SPECIFIC SAFETY RULES AND PRECAUTIONS
1. Only Natural gas or Propane (LP) gas are approved for use with
this furnace. Refer to the furnace rating plate or SECTION IV of
these instructions.
2. Install this furnace only in a location and position as specified in
SECTION I of these instructions.
3. A gas-fired furnace for installation in a residential garage must be
installed as specified in SECTION I of these instructions.
4. Provide adequate combustion and ventilation air to the furnace
space as specified in SECTION VI of these instructions.
5. Combustion products must be discharged outdoors. Connect this
furnace to an approved vent system only, as specified in SEC-
TION VI of these instructions.
6. Test for gas leaks as specified in SECTION VIII of these instruc-
tions.
7. Always install the furnace to operate within the furnace’s intended
temperature rise range. Only connect the furnace to a duct system
which has an external static pressure within the allowable range,
as specified on the furnace rating plate.
8. When a furnace is installed so that supply ducts carry air circulated
by the furnace to areas outside the space containing the furnace,
the return air shall also be handled by duct(s) sealed to the fur-
nace casing and terminating outside the space containing the fur-
nace.
9. It is permitted to use the furnace for heating of buildings or struc-
tures under construction. Installation must comply with all manu-
facturer’s installation instructions including:
• Proper vent installation;
• Furnace operating under thermostatic control;
• Return air duct sealed to the furnace;
• Air filters in place;
• Set furnace input rate and temperature rise per rating plate
marking;
• Means for providing outdoor air required for combustion;
• Return air temperature maintained between 55ºF (13ºC) and
80ºF (27ºC);
• The air filter must be replaced upon substantial completion of
the construction process;
• Clean furnace, duct work and components upon substantial
completion of the construction process, and verify furnace-
operating conditions including ignition, input rate, temperature
rise and venting, according to the manufacturer’s instructions.
10. When installed in an Approved Modular Home or building con-
structed on-site, combustion air shall not be supplied from occu-
pied spaces.
11. The size of the unit should be based on an acceptable heat loss
calculation for the structure. ACCA, Manual J or other approved
methods may be used.
SAFETY REQUIREMENTS
• This furnace should be installed in accordance with all national
and local building/safety codes and requirements, local plumbing
or waste water codes, and other applicable codes. In the absence
of local codes, install in accordance with the National Fuel Gas
Code ANSI Z223.1/NFPA 54, National Fuel Gas Code, and/or
CAN/CGA B149.1 Natural Gas and Propane Installation Code
(latest editions). Furnaces have been certified to the latest edition
of standard ANSI Z21-47 • CSA 2.3.
• Refer to the unit rating plate for the furnace model number, and
then see the dimensions page of this instruction for return air ple-
num dimensions in Figure 1. The plenum must be installed
according to the instructions.
• Provide clearances from combustible materials as listed under
Clearances to Combustibles in Table 1.
• Provide clearances for servicing ensuring that service access is
allowed for both the burners and blower.
• These models ARE NOT CSA listed or approved for installation
into a Manufactured (Mobile) Home.
• This furnace is not approved for installation in trailers or recre-
ational vehicles.
• Failure to carefully read and follow all instructions in this
manual can result in furnace malfunction, death, personal
injury and/or property damage.
• Furnaces for installation on combustible flooring shall not be
installed directly on carpeting, tile or other combustible material
other than wood flooring.
• Check the rating plate and power supply to be sure that the elec-
trical characteristics match. All models use nominal 115 VAC, 1
Phase, 60-Hertz power supply. DO NOT CONNECT THIS APPLI-
ANCE TO A 50 HZ POWER SUPPLY OR A VOLTAGE ABOVE
130 VOLTS.
• Furnace shall be installed so the electrical components are pro-
tected from water.
• Installing and servicing heating equipment can be hazardous due
to the electrical components and the gas fired components. Only
trained and qualified personnel should install, repair, or service
gas heating equipment. Untrained service personnel can perform
basic maintenance functions such as cleaning and replacing the
air filters. When working on heating equipment, observe precau-
tions in the manuals and on the labels attached to the unit and
other safety precautions that may apply.
• These instructions cover minimum requirements and conform to
existing national standards and safety codes. In some instances
these instructions exceed certain local codes and ordinances,
especially those who have not kept up with changing residential
and modular home construction practices. These instructions are
required as a minimum for a safe installation.
COMBUSTION AIR QUALITY
(LIST OF CONTAMINANTS)
The furnace will require OUTDOOR AIR for combustion when the fur-
nace is located in any of the following environments.
• Restricted environments
• Commercial buildings
• Buildings with indoor pools
• Furnaces installed in laundry rooms
• Furnaces installed in hobby or craft rooms
• Furnaces installed near chemical storage areas
• Chemical exposure
The furnace will require OUTDOOR AIR for combustion when the fur-
nace is located in an area where the furnace is being exposed to the fol-
lowing substances and / or chemicals.
• Permanent wave solutions
• Chlorinated waxes and cleaners
• Chlorine based swimming pool chemicals
• Water softening chemicals
• De-icing salts or chemicals
• Carbon tetrachloride
• Halogen type refrigerants
• Cleaning solvents (such as perchloroethylene)
• Printing inks, paint removers, varnishes, etc.
• Hydrochloric acid
• Cements and glues
• Anti-static fabric softeners for clothes dryers
• Masonry acid washing materials
When outdoor air is used for combustion, the combustion air intake duct
system termination must be located external to the building and in an
area where there will be no exposure to the substances listed above.
FIRE OR EXPLOSION HAZARD
Failure to follow the safety warnings exactly could result in serious
injury, death or property damage.
Never test for gas leaks with an open flame. Use a commercially
available soap solution made specifically for detection of leaks to
check all connections. A fire or explosion may result causing prop-
erty damage, personal injury or loss of life.

272312-UIM-A-0407
Unitary Products Group 3
INSPECTION
As soon as a unit is received, it should be inspected for possible dam-
age during transit. If damage is evident, the extent of the damage
should be noted on the carrier’s freight bill. A separate request for
inspection by the carrier’s agent should be made in writing. Also, before
installation the unit should be checked for screws or bolts, which may
have loosened in transit. There are no shipping or spacer brackets
which need to be removed.
FURNACE LOCATION AND CLEARANCES
The furnace shall be located using the following guidelines:
1. Where a minimum amount of air intake/vent piping and elbows will
be required.
2. As centralized with the air distribution as possible.
3. Where adequate combustion air will be available (particularly
when the appliance is not using outdoor combustion air).
4. Where it will not interfere with proper air circulation in the confined
space.
5. Where the outdoor vent terminal will not be blocked or restricted.
Refer to “VENT CLEARANCES” located in SECTION VI of these
instructions. These minimum clearances must be maintained in
the installation.
6. Where the unit will be installed in a level position with no more
than 1/4” (6.4 mm) slope side-to-side and front-to-back.
Installation in freezing temperatures:
1. Furnace shall be installed in an area where ventilation facilities
provide for safe limits of ambient temperature under normal oper-
ating conditions. Ambient temperatures may fall below 32° F (0° C)
providing the flue temperature does not fall below 260° F (127° C)
at any point in the flue pipe between the furnace and the chimney
or a B-Vent. The flue products will condense in the vent pipe if the
flue temperature falls below 260° F (127° C) causing the vent pipe
to deteriorate rapidly.
2. Do not allow return air temperature to be below 55º F (13° C) for
extended periods. To do so may cause condensation to occur in
the main heat exchanger, leading to premature heat exchanger
failure.
3. If this furnace is installed in an unconditioned space and an
extended power failure occurs, there will be potential damage to
the internal components. Following a power failure situation, do
not operate the unit until inspection and repairs are performed.
Clearances for access:
Ample clearances should be provided to permit easy access to the unit.
The following minimum clearances are recommended:
1. Twenty-four (24) inches (61 cm) between the front of the furnace
and an adjacent wall or another appliance, when access is
required for servicing and cleaning.
2. Eighteen (18) inches (46 cm) at the side where access is required
for passage to the front when servicing or for inspection or
replacement of flue/vent connections.
In all cases, accessibility clearances shall take precedence over clear-
ances for combustible materials where accessibility clearances are
greater.
Installation in a residential garage:
A gas-fired furnace for installation in a residential garage must be
installed so the burner(s) and the ignition source are located not less
than 18 inches (46 cm) above the floor, and the furnace must be located
or protected to avoid physical damage by vehicles.
The furnace area must not be used as a broom closet or for any
other storage purposes, as a fire hazard may be created. Never
store items such as the following on, near, or in contact with the fur-
nace.
1. Spray or aerosol cans, rags, brooms, dust mops, vacuum
cleaners or other cleaning tools.
2. Soap powders, bleaches, waxes, or other cleaning com-
pounds; plastic items or containers; gasoline, kerosene, ciga-
rette lighter fluid, dry cleaning fluids or other volatile fluid.
3. Paint thinners and other painting compounds.
4. Paper bags, boxes, or other paper products
Never operate the furnace with the blower door removed. To
do so could result in serious personal injury and/or equipment
damage.
FOR FURNACES INSTALLED IN THE COMMON-
WEALTH OF MASSACHUSETTS ONLY
For all side wall horizontally vented gas fueled equipment installed in
every dwelling, building or structure used in whole or in part for resi-
dential purposes, including those owned or operated by the Com-
monwealth and where the side wall exhaust vent termination is less
than seven (7) feet above finished grade in the area of the venting,
including but not limited to decks and porches, the following require-
ments shall be satisfied:
1. INSTALLATION OF CARBON MONOXIDE DETECTORS. At
the time of installation of the side wall horizontal vented gas
fueled equipment, the installing plumber or gasfitter shall
observe that a hard wired carbon monoxide detector with an
alarm and battery back-up is installed on the floor level where
the gas equipment is to be installed. In addition, the installing
plumber or gasfitter shall observe that a battery operated or
hard wired carbon monoxide detector with an alarm is installed
on each additional level of the dwelling, building or structure
served by the side wall horizontal vented gas fueled equipment.
It shall be the responsibility of the property owner to secure the
services of qualified licensed professionals for the installation of
hard wired carbon monoxide detectors
a. In the event that the side wall horizontally vented gas
fueled equipment is installed in a crawl space or an attic,
the hard wired carbon monoxide detector with alarm and
battery back-up may be installed on the next adjacent floor
level.
b. In the event that the requirements of this subdivision can
not be met at the time of completion of installation, the
owner shall have a period of thirty (30) days to comply with
the above requirements; provided, however, that during
said thirty (30) day period, a battery operated carbon mon-
oxide detector with an alarm shall be installed.
2. APPROVED CARBON MONOXIDE DETECTORS. Each car-
bon monoxide detector as required in accordance with the
above provisions shall comply with NFPA 720 and be ANSI/UL
2034 listed and IAS certified.
3. SIGNAGE. A metal or plastic identification plate shall be perma-
nently mounted to the exterior of the building at a minimum
height of eight (8) feet above grade directly in line with the
exhaust vent terminal for the horizontally vented gas fueled
heating appliance or equipment. The sign shall read, in print
size no less than one-half (1/2) inch in size, "GAS VENT
DIRECTLY BELOW. KEEP CLEAR OF ALL OBSTRUC-
TIONS".
4. INSPECTION. The state or local gas inspector of the side wall
horizontally vented gas fueled equipment shall not approve the
installation unless, upon inspection, the inspector observes car-
bon monoxide detectors and signage installed in accordance
with the provisions of 248 CMR 5.08(2)(a)1 through 4.
Improper installation in an ambient below 32ºF (0.0° C) could create
a hazard, resulting in damage, injury or death.

272312-UIM-A-0407
4Unitary Products Group
SECTION II: DUCTWORK
DUCTWORK GENERAL INFORMATION
The duct system’s design and installation must:
1. Handle an air volume appropriate for the served space and within
the operating parameters of the furnace specifications.
2. Be installed in accordance with standards of NFPA (National Fire
Protection Association) as outlined in NFPA pamphlets 90A and
90B (latest editions) or applicable national, provincial, or state, and
local fire and safety codes.
3. Create a closed duct system. For residential and Modular Home
installations, when a furnace is installed so that the supply ducts
carry air circulated by the furnace to areas outside the space con-
taining the furnace, the return air shall also be handled by a duct(s)
sealed to the furnace casing and terminating outside the space
containing the furnace.
4. Complete a path for heated or cooled air to circulate through the
air conditioning and heating equipment and to and from the condi-
tioned space.
When the furnace is used in conjunction with a cooling coil, the coil
must be installed parallel with, or in the supply air side of the furnace to
avoid condensation in the primary heat exchanger. When a parallel flow
arrangement is used, dampers or other means used to control airflow
must be adequate to prevent chilled air from entering the furnace. If
manually operated, the damper must be equipped with means to pre-
vent the furnace or the air conditioner from operating unless the damper
is in full heat or cool position.
DUCTWORK INSTALLATION AND SUPPLY PLENUM
CONNECTION
A proper heat loss/gain calculation should be done on all
installations for proper application of equipment. From this,
the ductwork sizing can be calculated. ACCA Manual J and
D and industry standards are helpful.
Attach the supply plenum to the furnace or coil outlet duct
connection flanges. This is typically through the use of S
cleat material when a metal plenum is used. The use of an
approved flexible duct connector is recommended on all
installations to prevent noise transmission. All connections should be
sealed to prevent air leakage. Sheet metal should be crosshatched to
eliminate any popping when the indoor fan is energized.
When replacing an existing furnace, if the existing supply plenum is not
the same size as the new furnace then the existing plenum must be
removed and a new plenum installed that is of the proper size for the
new furnace. If the plenum is shorter than 12” (30.5 cm) the turbulent air
flow may cause the limit controls not to operate as designed, if at all.
The duct system is a very important part of the installation. If the duct
system is improperly sized the furnace will not operate properly.
The ducts attached to the furnace plenum should be of sufficient size so
that the furnace operates at the specified external static pressure and
within the air temperature rise specified on the nameplate.
Table 2 is a guide for determining whether the rectangular duct system
that the furnace is being connected to be of sufficient size for proper fur-
nace operation.
Use the Example below to help you in calculating the duct area to deter-
mine whether the ducts have sufficient area so that the furnace oper-
ates at the specified external static pressure and within the air
temperature rise specified on the nameplate.
The following are general duct sizing guidelines that may not serve to
requirements of every application.
Example: The furnace input is 80,000 BTUH with 1,200 CFM blower
requirement. The recommended duct area is 216 sq.in, there are two 8
x 12 rectangular ducts attached to the plenum and there are two 7 inch
round ducts attached to the furnace.
1. Take 8 x 12, which equals 96 sq.in. X 2, which equals 192 square
inches then go to round duct size located in Table 3.
2. The square inch area for 7 inch round ducts is 38.4 sq. in. x 2 =
76.8 square inches.
3. Then take the 192 square inch from the rectangular duct and add it
to the 76.8 sq.in. of round duct. The total square inch of duct
attached to the furnace supply plenum is 268.8 total square
inches. This exceeds the recommended 216 square inch of duct.
In this example, the duct system attached to the plenum has a sufficient
area so that the furnace operates at the specified external static pres-
sure and within the air temperature rise specified on the nameplate,
providing the return duct is properly sized as well.
TABLE 1:
Unit Clearances to Combustibles (All Dimensions in Inches, and All Surfaces Identified with the Unit in an Upflow Configuration)
Application Top Front Rear Left Side Right Side Flue Floor/
Bottom Closet Alcove Attic Line
Contact
In. (cm) In. (cm) In. (cm) In. (cm) In. (cm) In. (cm)
Upflow 1 (2.5) 6 (15.2) 0 (0.0) 0 (0.0) 3 (7.6) 6 (15.2) Combustible Yes Yes Yes No
Upflow B-Vent 1 (2.5) 3 (7.6) 0 (0.0) 0 (0.0) 0 (0.0) 1 (2.5) Combustible Yes Yes Yes No
Horizontal 1 (2.5) 6 (15.2) 0 (0.0) 0 (0.0) 3 (7.6) 6 (15.2) Combustible No Yes Yes Yes1
Horizontal B-Vent 1 (2.5) 3 (7.62) 0 (0.0) 0 (0.0) 0 (0.0) 1 (2.5) Combustible No Yes Yes Yes1
1. Line contact only permitted between lines formed by the intersection of the rear panel and side panel (top in horizontal position) of the furnace jacket and building
joists, studs or framing.
The cooling coil must be installed in the supply air duct, down-
stream of the furnace. Cooled air may not be passed over the heat
exchanger.
The duct system must be properly sized to obtain the correct airflow
for the furnace size that is being installed.
Refer to Table 8 and the furnace rating plate for the correct rise
range and static pressures
If the ducts are undersized, the result will be high duct static pres-
sures and/or high temperature rises which can result in a heat
exchanger OVERHEATING CONDITION. This condition can result
in premature heat exchanger failure, which can result in personal
injury, property damage, or death.

272312-UIM-A-0407
Unitary Products Group 5
1. The Air Temperature Rise is determined by subtracting the Return
Air Temperature Reading from the Supply Air Temperature Read-
ing.
2. The External Static Pressure is determined by adding the Supply
Duct Static Pressure reading to the Return Duct Static Pressure
reading and adding the pressure drop across any applied a-coil
and return air filter.
Tables 2 & 3 is to be used as a guide only to help the installer determine
if the duct sizes are large enough to obtain the proper air flow (CFM)
through the furnace. Tables 2 & 3 ARE NOT to be used to design duct-
work for the building where the furnace is being installed. There are
several variables associated with proper duct sizing that are not
included in the tables. To properly design the ductwork for the building,
refer to the ASHRAE Fundamentals Handbook, Chapter on “DUCT
DESIGN” or a company that specializes in Residential and Modular
Home duct designs.
IMPORTANT: The minimum plenum height is 12” (30.5 cm). The fur-
nace will not operate properly on a shorter plenum height. The mini-
mum recommended rectangular duct height is 4 inches (10 cm)
attached to the plenum.
IMPORTANT: The air temperature rise should be taken only after the
furnace has been operating for at least 15 minutes. Temperatures and
external static pressures should be taken 6” (15 cm) past the first bend
from the furnace in the supply duct and the return duct. If an external fil-
ter box or an electronic air cleaner is installed, take the return air read-
ings before the filter box or air cleaner.
If a matching cooling coil is used, it may be placed directly on the fur-
nace outlet and sealed to prevent leakage. Follow the coil instructions
for installing the supply plenum. On all installations without a coil, a
removable access panel is recommended in the outlet duct such that
smoke or reflected light would be observable inside the casing to indi-
cate the presence of leaks in the heat exchanger. This access cover
shall be attached in such a manner as to prevent leaks.
TABLE 2:
Minimum Duct Sizing For Proper Airflow
Airflow Return1Rectangular2Round2Supply3Rectangular2Round2
CFM (m³/min) In² (cm²) in. x in. (cm x cm) in. (cm) dia. In² (cm²) in. x in. (cm x cm) in. (cm) dia.
1,200 (34) 280 (1806) 14 x 20 (35.6 x 50.8) 18 (45.7) 216 (1393) 12 x 18 (30.5 x 45.7) 16 (40.6)
1,600 (45.3) 360 (2322) 18 x 20 (45.7 x 50.8) 22 (55.8) 280 (1806) 14 x 20 (35.6 x 50.8) 18 (45.7)
2,000 (56.6) 440 (2838) 20 x 22 (50.8 x 55.8) 24 (60.9) 390 (2516) 16 x 22 (40.6 x 55.8) 22 (55.8)
NOTE: This chart does not replace proper duct sizing calculations or take into account static pressure drop for run length and fittings. Watch out for the temperature rise
and static pressures.
1. Maximum return air velocity in rigid duct @ 700 feet per minute (213 m/min).
2. Example return main trunk duct minimum dimensions.
3. Maximum supply air velocity in rigid duct @ 900 feet per minute (274m/min).
TABLE 3: Round Duct Size
Round Duct Size Calculated Area For Each Round Duct Size
inches (cm) Sq.in (cm2)
5 (13) 19.6 (126)
6 (15) 28.2 (182)
7 (18) 38.4 (248)
8 (20) 50.2 (324)
9 (23) 63.6 (410)
10 (25) 78.5 (506)
11 (28) 95 (613)
12 (30) 113.1 (730)
13 (33) 132.7 (856)
14 (36) 153.9 (993)
The supply air temperature MUST NEVER exceed the Maximum
Outlet Air Temperature, specified on the nameplate.
Operating the furnace above the maximum outlet air temperature
will cause the heat exchanger to overheat, causing premature heat
exchanger failure. Improper duct sizing, dirty air filters, incorrect
manifold pressure, incorrect gas orifice and/or a faulty limit switch
can cause the furnace to operate above the maximum supply air
temperature. Refer to sections II, III and VIII for additional informa-
tion on correcting the problem.

272312-UIM-A-0407
6Unitary Products Group
RESIDENTIAL AND MODULAR HOME UPFLOW
RETURN PLENUM CONNECTION
Return air may enter the furnace through the side(s) or bottom depend-
ing on the type of application. Return air may not be connected into the
rear panel of the unit. In order to achieve the airflow indicated, it is rec-
ommended those applications over 1800 CFM (51 m³/min) use return
air from two sides, one side and the bottom or bottom only. For single
return application, see data and notes on blower performance data
tables in this manual.
BOTTOM RETURN AND ATTIC INSTALLATIONS
Bottom return applications normally pull return air through a base plat-
form or return air plenum. Be sure the return platform structure or return
air plenum is suitable to support the weight of the furnace.
The furnace base is equipped with a rectangular blockoff panel that can
be removed by performing the following steps:
1. Lay the furnace on its back.
2. Remove the screws from the toe plate.
3. Remove the toe plate.
4. Pull the base plate out of the furnace base.
5. Reinstall the toe plate and secure with the screws that were
removed.
Attic installations must meet all minimum clearances to combustibles
and have floor support with required service accessibility.
IMPORTANT: If an external mounted filter rack is being used see the
instructions provided with that accessory for proper hole cut size.
HORIZONTAL MODELS
IMPORTANT: This furnace may be installed in a horizontal position on
either side as shown above. It must not be installed on its back.
FIGURE 1: Dimensions
A
40
26-1/2
1-1/2
1-1/4
C
20 5/8
5/8
B
24-3/4
FRONT
BOTTOM IMAGE
RETURN END TOP IMAGE
SUPPLY END
D
4” Diameter
LEFT SIDE RIGHT SIDE
20
30-1/8
14-3/4
5-3/8
(VENT CONNECTION)
POWER WIRING
7/8” HOLE
2-1/2
ACCESS
WIRING
7/8” K.O.
16
8-3/4
T’STAT WIRING
7/8” K.O.
1-1/8
2-1/4
14
23-1/2
32-1/2
2
13-3/4
GAS INLET
1-1/4 x 2-1/2
B
4” Diameter
3/4
TABLE 4: Cabinet and Duct Dimensions
BTUH Input CFM (m3/min) Cabinet
Size Cabinet Dimension
MBH kW A A (cm) B B (cm) C C (cm) D D (cm)
40/26 11.7/7.6 1200 (33.98) A 14 1/2 36.8 13 1/4 33.6 11 1/2 29.2 10 1/8 25.7
57/42 17.6/12.3 1200 (33.98) A 14 1/2 36.8 13 1/4 33.6 11 1/2 29.2 10 1/8 25.7
80/59 23.4/17.3 1200 (33.98) A 14 1/2 36.8 13 1/4 33.6 11 1/2 29.2 10 1/8 25.7
80/59 23.4/17.3 1600 (45.31) B 17 1/2 44.4 16 1/4 41.3 14 1/2 36.8 11 5/8 29.5
80/59 23.4/17.3 1600 (45.31) C 21 53.3 19 3/4 50.2 18 45.7 13 3/8 34
100/65 29.3/19.1 1200 (33.98) B 17 1/2 44.4 16 1/4 41.3 14 1/2 36.8 11 5/8 29.5
100/65 29.3/19.1 2000 (56.63) C 21 53.3 19 3/4 50.2 18 45.7 13 3/8 34
120/78 35.2/22.9 1600(45.31) C 21 53.3 19 3/4 50.2 18 45.7 13 3/8 34
120/78 35.2/22.9 2000 (56.63) C 21 53.3 19 3/4 50.2 18 45.7 13 3/8 34

272312-UIM-A-0407
Unitary Products Group 7
Horizontal Installations With a Cooling Coil Cabinet
The furnace should be installed with coil cabinet part number specifi-
cally intended for Horizontal application. If a matching cooling coil is
used, it may be placed directly on the furnace outlet and sealed to pre-
vent leakage. Follow the coil instructions for installing the supply ple-
num. For details of the coil cabinet dimensions and installation
requirements, refer to the installation instructions supplied with the coil
cabinet
Attach the supply plenum to the air conditioning coil cabinet outlet duct
flanges through the use of S cleat material when a metal plenum is
used. The use of an approved flexible duct connector is recommended
on all installations. The connection to the furnace, air conditioning coil
cabinet and the supply plenum should be sealed to prevent air leakage.
The sheet metal should be crosshatched to eliminate any popping of
the sheet metal when the indoor fan is energized.
The minimum plenum height is 12” (30.5 cm). If the plenum is shorter
than 12” (30.5 cm) the turbulent air flow may cause the limit controls not
to operate as designed, or the limit controls may not operate at all. Also
the plastic drain pan in the air conditioning coil can overheat and melt.
Refer to the installation instructions supplied with the air conditioning
coil for additional information.
Horizontal Installations Without a Cooling Coil Cabinet
When installing this appliance, the furnace must be installed so as to
create a closed duct system, the supply duct system must be con-
nected to the furnace outlet and the supply duct system must terminate
outside the space containing the furnace. When replacing an existing
furnace, if the existing plenum is not the same size as the new furnace
then the existing plenum must be removed and a new plenum installed
that is the proper size for the new furnace.
Attach the supply plenum to the furnace outlet duct flanges through the
use of S cleat material when a metal plenum is used. The use of an
approved flexible duct connector is recommended on all installations.
This connection should be sealed to prevent air leakage. The sheet
metal should be crosshatched to eliminate any popping of the sheet
metal when the indoor fan is energized. On all installations without a
coil, a removable access panel is recommended in the outlet duct such
that smoke or reflected light would be observable inside the casing to
indicate the presence of leaks in the heat exchanger. This access cover
shall be attached in such a manner as to prevent leaks.
Residential and Modular Home Horizontal Return Plenum
Connections
The return duct system must be connected to the furnace inlet and the
return duct system must terminate outside the space containing the fur-
nace. When replacing an existing furnace, if the existing plenum is not
the same size as the new furnace then the existing plenum must be
removed and a new plenum installed that is the proper size for the new
furnace.
Attach the return plenum to the furnace inlet duct flanges. This is typi-
cally through the use of S cleat material when a metal plenum is used.
The use of an approved flexible duct connector is recommended on all
installations. The connection of the plenum to the furnace and all the
ducts connecting to the plenum must be sealed to prevent air leakage.
The sheet metal should be crosshatched to eliminate any popping of
the sheet metal when the indoor fan is energized.
The duct system is a very important part of the installation. If the duct
system is improperly sized the furnace will not operate properly. The
ducts attached to the furnace must be of sufficient size so that the fur-
nace operates at the specified external static pressure and within the air
temperature rise specified on the nameplate.
Attic installations must meet all minimum clearances to combustibles
and have floor support with required service accessibility.
IMPORTANT: if an external mounted filter rack is being used see the
instructions provided with that accessory for proper hole cut size.
ATTIC INSTALLATION
This appliance is design certified for line contact when the furnace is
installed in the horizontal left or right position. The line contact is only
permissible between lines that are formed by the intersection of the top
and two sides of the furnace and the building joists, studs or framing.
This line may be in contact with combustible material.
SUSPENDED FURNACE / CRAWL SPACE
INSTALLATION
The furnace can be hung from floor joists or installed on suitable blocks
or pad. Blocks or pad installations shall provide adequate height to
ensure the unit will not be subject to water damage. Units may also be
suspended from rafters or floor joists using rods, pipe angle supports or
straps. Angle supports should be placed at the supply air end and near
the blower deck. Do not support at return air end of unit. All four sus-
pension points must be level to ensure quite furnace operation. When
suspending the furnace use a secure platform constructed of plywood
or other building material secured to the floor joists. Refer to Figure 3
for typical crawl space installation.
FIGURE 2: Typical Attic Installation
When a furnace is installed in an attic or other insulated space,
keep all insulating materials at least 12 inches (30.5 cm) away from
furnace and burner combustion air openings.
FIGURE 3: Typical Suspended Furnace / Crawl Space Installation
In any application where temperatures below freezing are possible,
see “INSTALLATION IN FREEZING TEMPERATURES” in Section I
RETURN AIR SEDIMENT
TRAP
GAS PIPING
SUPPLY AIR
VENT (Maintain
required clearances
to combustibles)
LINE CONTACT ONLY PERMISSIBLE
BETWEEN LINES FORMED BY THE
INTERSECTION OF FURNACE TOP
AND TWO SIDES AND BUILDING
JOISTS, STUDS OR FRAMING
12”
30” MIN.
WORK AREA
FILTER RACK
MUST BE A MINIMUM
DISTANCE
OF 18” (45.7 cm)
FROM THE
FURNACE
12”
SHEET METAL
IN FRONT OF
FURNACE
COMBUSTION AIR
OPENINGS IS
RECOMMENDED
ANGLE IRON
BRACKET
6” MIN. BETWEEN
ROD & FRONT OF FURNACE 1” MAX. BETWEEN
ROD & BACK OF FURNACE
SUPPORT
BRACKET

272312-UIM-A-0407
8Unitary Products Group
SECTION III: FILTERS
FILTER INSTALLATION
All applications require the use of an external filter. All filters and mount-
ing provision must be field supplied. Refer to Tables 5 & 16 for acces-
sory external filter kit options.
NOTES:
1. Air velocity through throwaway type filters may not exceed 300 feet
per minute. All velocities over this require the use of high velocity fil-
ters.
2. Air flows above 1800 CFM require either return from two sides or
one side plus bottom.
SIDE RETURN - EXTERNAL INSTALLATION
Locate and knock out the square corner locators. These indicate the
size of the cutout to be made in the furnace side panel. Refer to Figure 4.
Install the side filter rack following the instructions provided with that
accessory. If a filter(s) is provided at another location in the return air
system, the ductwork may be directly attached to the furnace side
panel.
IMPORTANT: Some accessories such as electronic air cleaners and
pleated media may require a larger side opening. Follow the instruc-
tions supplied with that accessory for side opening requirements. Do
not cut the opening larger than the dimensions shown in Figure 1.
HORIZONTAL APPLICATION
Horizontal Filters
All filters and mounting provision must be field supplied. Filters(s) may
be located in the duct system external to the furnace or in a return filter
grille(s). Filters(s) may be located in the duct system using an external
duct filter box attached to the furnace plenum. Any branch duct (rectan-
gular or round duct) attached to the plenum must attach to the vertical
plenum above the filter height. The use of straps and / or supports is
required to support the weight of the external filter box.
IMPORTANT: Air velocity through throwaway type filters must not
exceed 300 feet per minute (91 m/min). All velocities over this require
the use of high velocity filters. Refer to Table 15.
SECTION IV: GAS PIPING
GAS SAFETY
IMPORTANT: Plan your gas supply before determining the correct gas
pipe entry. Use 90-degree service elbow(s), or short nipples and con-
ventional 90-degree elbow(s) to enter through the cabinet access holes.
GAS PIPING INSTALLATION
Properly sized wrought iron, approved flexible or steel pipe must be
used when making gas connections to the unit. If local codes allow the
use of a flexible gas appliance connection, always use a new listed con-
nector. Do not use a connector that has previously serviced another gas
appliance.
Some utility companies or local codes require pipe sizes larger than the
minimum sizes listed in these instructions and in the codes. The fur-
nace rating plate and the instructions in this section specify the type of
gas approved for this furnace - only use those approved gases. The
installation of a drip leg and ground union is required. Refer to Figures 6
& 7.
TABLE 5:
Recommended Filter Sizes
Cabinet Size Side (in) Side (cm) Bottom (in) Bottom (cm)
A 16 x 25 40.6 x 64.0 14 x 25 35.6 x 64.0
B 16 x 25 40.6 x 64.0 16 x 25 40.6 x 64.0
C (2) 16 x 25 (2) 40.6 x 64.0 20 x 25 50.8 x 64.0
FIGURE 4: Side Return Cutout Markings
All installations must have a filter installed.
FRONT OF
FURNACE
CORNER
MARKINGS
An overpressure protection device, such as a pressure regulator,
must be installed in the gas piping system upstream of the furnace
and must act to limit the downstream pressure to the gas valve so it
does not exceed 0.5 PSI (14" w.c. (3.48 kPa). Pressures exceeding
0.5 PSI (14” w.c. (3.48 kPa) at the gas valve will cause damage to
the gas valve, resulting in a fire or explosion or cause damage to
the furnace or some of its components that will result in property
damage and loss of life.
FIGURE 5: Gas Valve
FIGURE 6: Upflow Gas Piping
INLET
WRENCH
BOSS
INLET
PRESSURE
PORT ON OFF
SWITCH
LOW STAGE REGULATOR
ADJUSTMENT
OUTLET
OUTLET
PRESSURE
PORT VENT
PORT
HIGH STAGE REGULATOR
ADJUSTMENT
EXTERNAL MANUAL
SHUTOFF VALVE
TO GAS
SUPPLY
TO GAS
SUPPLY
GROUNDED JOINT UNION
MAY BE INSTALLED
INSIDE OR OUTSIDE UNIT.
DRIP
LEG

272312-UIM-A-0407
Unitary Products Group 9
IMPORTANT: An accessible manual shutoff valve must be installed
upstream of the furnace gas controls and within 6 feet (1.8 m) of the fur-
nace.
The furnace must be isolated from the gas supply piping system by
closing its individual external manual shutoff valve during any pressure
testing of the gas supply piping system at pressures equal to or less
than 1/2 psig (3.5 kPa).
Gas piping may be connected from either side of the furnace using any
of the gas pipe entry knockouts on both sides of the furnace. Refer to
Figure 1 dimensions.
GAS ORIFICE CONVERSION FOR PROPANE (LP)
This furnace is constructed at the factory for natural gas-fired operation,
but may be converted to operate on propane (LP) gas by using a fac-
tory-supplied LP conversion kit. Follow the instructions supplied with
the LP kit. Refer to the instructions in the propane (LP) conversion kit
for the proper gas orifice size.
HIGH ALTITUDE GAS ORIFICE CONVERSION
This furnace is constructed at the factory for natural gas-fired operation
at 0 – 8,000 feet (0-m – 2,438 m) above sea level.
The manifold pressure must be changed in order to manitain proper
and safe operation when the furnace is installed in a location where the
altitude is greater than 8,000 feet (2,438 m) above sea level. Refer to to
Tables 6 & 7 for proper manifold pressure settings.
HIGH ALTITUDE PRESSURE SWITCH CONVERSION
For installation where the altitude is less than 8,000 feet (2,438 m), it is
not required that the pressure switch be changed. For altitudes above
8,000 feet (2,438 m), see Table 16 Field Installed Accessories - High
Altitude Pressure Switch
FIGURE 7: Horizontal Gas Piping
The gas valve body is a very thin casting that cannot take any
external pressure. Never apply a pipe wrench to the body of the gas
valve when installing piping. A wrench must be placed on the octag-
onal hub located on the gas inlet side of the valve. Placing a wrench
to the body of the gas valve will damage the valve causing improper
operation and/or the valve to leak.
MANUAL
SHUT-OFF
VALVE
GAS
PIPE
GAS
PIPE
DRIP
LEG
MANUAL
SHUT-OFF VALVE
GAS VALVE
GAS BURNERS
DRIP
LEG
LoNOx furnaces requiring propane (LP) gas must have the LoNOx
screens removed prior to installation and operation. See the
instructions supplied with the propane conversion kit or the start up
procedure at the back of these instructions on proper removal of the
NOx screens.
TABLE 6: Nominal Manifold Pressure - High Fire
Single/Second Stage Manifold Pressures (in wc) Single/Second Stage Manifold Pressures (kpa)
Altitude (feet) Altitude (m)
0-7999 8000-8999 9000-9999 0-2437 2438-2742 2743-3048
Gas Heating Value
(BTU/cu ft.)
800 3.5 3.5 3.5
Gas Heating Value
(MJ/cu m)
29.8 0.87 0.87 0.87
850 3.5 3.5 3.5 31.7 0.87 0.87 0.87
900 3.5 3.5 3.5 33.5 0.87 0.87 0.87
950 3.5 3.5 3.3 35.4 0.87 0.87 0.81
1000 3.5 3.2 2.9 37.3 0.87 0.80 0.73
1050 3.5 2.9 2.7 39.1 0.87 0.73 0.67
1100 3.2 2.7 2.4 41.0 0.80 0.66 0.61
2500 (LP) 9.8 8.2 7.5 93.2 (LP) 2.44 2.03 1.86
TABLE 7: Nominal Manifold Pressure - Low Fire
First Stage Manifold Pressures (in wc) First Stage Manifold Pressures (kpa)
Altitude (feet) Altitude (m)
0-7999 8000-8999 9000-9999 0-2437 2438-2742 2743-3048
Gas Heating Value
(BTU/cu ft.)
800 1.7 1.7 1.7
Gas Heating Value
(MJ/cu m)
29.8 0.42 0.42 0.42
850 1.7 1.7 1.7 31.7 0.42 0.42 0.42
900 1.7 1.7 1.7 33.5 0.42 0.42 0.42
950 1.7 1.7 1.5 35.4 0.42 0.42 0.38
1000 1.6 1.5 1.4 37.3 0.41 0.37 0.34
1050 1.5 1.4 1.3 39.1 0.37 0.34 0.31
1100 1.3 1.2 1.1 41.0 0.34 0.31 0.28
2500 (LP) 4.1 3.8 3.5 93.2 (LP) 1.03 0.95 0.87

272312-UIM-A-0407
10 Unitary Products Group
SECTION V: ELECTRICAL POWER
Electrical Power Connections
Field wiring to the unit must be grounded. Electric wires that are field
installed shall conform to the temperature limitation of 63°F (35°C) rise
when installed in accordance with these instructions. Refer to Table 8 in
these instructions for specific furnace electrical data.
1. Annual Fuel Utilization Efficiency (AFUE) numbers are determined in accordance with DOE Test procedures.
2. Field wiring and over-current protection (Max Fuse Size) must conform to and be grounded in accordance ANSI/NFPA
No. 70-latest edition or the Canadian Electrical Code C222.1 Part 1-latest edition and / or local codes.
3. Wire size based on copper conductors, 60º C, 3% voltage drop. "Unit Amps" refers to the full load current.
4. Min wire size (awg) @ 75 ft. one way refers to the minimum recommended field installed wire size.
PROPANE AND HIGH ALTITUDE CONVERSION KITS
It is very important to choose the correct kit and/or gas orifices for the altitude and the type of gas for which the furnace is being installed.
Only use natural gas in furnaces designed for natural gas. Only use propane (LP) gas for furnaces that have been properly converted to use pro-
pane (LP) gas. Do not use this furnace with butane gas.
Incorrect gas orifices or a furnace that has been improperly converted will create an extremely dangerous condition resulting in premature heat
exchanger failure, excessive sooting, high levels of carbon monoxide, personal injury, property damage, a fire hazard and/or death.
High altitude and propane (LP) conversions are required in order for the appliance to satisfactory meet the application.
An authorized distributor or dealer must make all gas conversions.
In Canada, a certified conversion station or other qualified agency, using factory specified and/or approved parts, must perform the conversion.
The installer must take every precaution to insure that the furnace has been converted to the proper gas orifice size when the furnace is installed.
Do not attempt to drill out any orifices to obtain the proper orifice size. Drilling out a gas orifice will cause misalignment of the burner flames,
causing premature heat exchanger burnout, high levels of carbon monoxide, excessive sooting, a fire hazard, personal injury, property damage
and/or death.
Use copper conductors only.
TABLE 8: Ratings & Physical / Electrical Data
Input
High/Low Output BTU/H High/Low Nominal Airflow Cabinet Width AFUE Blower Blower Size
MBH kW MBH kW CFM m3min In cm Hp Amps In cm
40/26 11.7/7.6 32/21 9.4/6.1 1200 34.0 14-1/2 36.8 80.0 1/2 7.7 10 x 8 25.4 x 20.3
57/42 16.7/12.3 46/34 13.5/10.0 1200 34.0 14-1/2 36.8 80.0 1/2 7.7 10 x 8 25.4 x 20.3
80/59 23.4/17.3 64/48 18.8/14.1 1200 34.0 14 1/2 36.8 80.0 1/2 7.7 10 x 8 25.4 x 20.3
80/59 23.4/17.3 64/48 18.8/14.1 1600 45.3 17-1/2 44.5 80.0 3/4 11.5 10 x 10 25.4 x 25.4
80/59 23.4/17.3 64/48 18.8/14.1 1600 45.3 21 53.3 80.0 3/4 11.5 10 x 10 25.4 x 25.4
100/65 29.3/19.1 80/53 23.4/15.5 1200 34.0 17 1/2 44.5 80.0 1/2 11.5 10 x 10 25.4 x 25.4
100/65 29.3/19.1 80/53 23.4/15.5 2000 56.6 21 53.3 80.0 1 14 11 x 10 27.9 x 25.4
120/78 35.1/22.9 96/64 28.1/18.8 1600 56.6 21 53.3 80.0 3/4 11.5 11 x 10 27.9 x 25.4
120/78 35.1/22.9 96/64 28.1/18.8 2000 56.6 21 53.3 80.0 1 14 11 x 11 27.9 x 25.4
Input/Cabinet
High/Low Max. Outlet Air Temp Low Fire Air Temp. Rise High Fire Air Temp. Rise Total
Unit
Amps
Max
Over-Current
Protect
Min. wire Size
(awg) @ 75 ft
one way
Operation
Weight
MBH kW °F °C °F °C °F °C Lbs Kg
40/26 11.7/7.6 150 83.3 15-45 8-25 20-50 11-28 9.0 20 14 107 48.5
57/42 16.7/12.3 160 71.1 25-55 14-31 35-65 19-36 9.0 20 14 107 48.5
80/52 23.4/17.3 175 79.4 30-60 17-33 40-70 22-39 9.0 20 14 117 53.2
80/59 23.4/17.3 160 71.1 25-55 14-31 25-55 14-31 12.0 20 14 129 58.5
80/59 23.4/17.3 160 71.1 25-55 14-31 25-55 14-31 12.0 20 14 130 59.1
100/65 29.3/19.1 170 76.7 25-55 14-31 40-70 22-39 12.9 20 14 128 58.2
100/65 29.3/19.1 170 76.7 25-55 14-31 40-70 22-39 14.0 20 14 145 65.9
120/78 35.1/22.9 180 76.7 25-55 14-31 45-75 25-41 12.0 20 14 145 65.9
120/78 35.1/22.9 170 76.7 25-55 14-31 35-65 19-36 14.0 20 12 147 66.8

272312-UIM-A-0407
Unitary Products Group 11
SUPPLY VOLTAGE CONNECTIONS
IMPORTANT: The power connection leads and wiring box may be relo-
cated to the left side of the furnace. Remove the screws and cut wire tie
holding excess wiring. Reposition on the left side of the furnace and fas-
ten using holes provided.
1. Provide a power supply separate from all other circuits. Install
overcurrent protection and disconnect switch per local/national
electrical codes. The switch should be close to the unit for conve-
nience in servicing. With the disconnect or fused switch in the OFF
position, check all wiring against the unit wiring label. Refer to the
wiring diagram, Figure 31, in this instruction.
2. Remove the screws retaining the junction box cover. Route the
power wiring through the opening in the unit into the junction box
with a conduit connector or other proper connection. In the junc-
tion box there will be three wires, a Black Wire, a White Wire and a
Green Wire. Connect the power supply as shown on the unit wiring
label on the inside of the blower compartment door or Figure 8.
The black furnace lead must be connected to the L1 (hot) wire
from the power supply. The white furnace lead must be connected
to neutral. Connect the green furnace lead (equipment ground) to
the power supply ground. An alternate wiring method is to use a
field provided 2” (5.1 cm) x 4” (10.2 cm) box and cover on the out-
side of the furnace. Route the furnace leads into the box using a
protective bushing where the wires pass through the furnace
panel. After making the wiring connections replace the wiring box
cover and screws.
3. The furnace's control system requires correct polarity of the power
supply and a proper ground connection. If the power supply polar-
ity is reversed, the control board will flash 9 times. The furnace will
not operate until the polarity is corrected. Refer to "FURNACE
DIAGNOSTICS" section of the “User’s Information, Maintenance,
& Service Manual” provided with this furnace for symptoms of
reversed power supply polarity.
LOW VOLTAGE CONTROL WIRING CONNECTIONS
Install the field-supplied thermostat by following the instructions that
come with the thermostat. With the thermostat set in the OFF position
and the main electrical source disconnected, connect the thermostat
wiring from the wiring connections on the thermostat to the terminal
board on the ignition module, as shown in Figures 9 & 10. Electronic
thermostats may require the common wire to be connected as shown in
Figures 9 & 10. Apply strain relief to thermostat wires passing through
cabinet. If air conditioning equipment is installed, use thermostat wiring
to connect the Y and C terminals on the furnace control board to the
proper wires on the condensing unit (unit outside).
IMPORTANT: Some electronic thermostats do not have adjustable
heat anticipators. They may have other type cycle rate adjustments.
Follow the thermostat manufacturer's instructions.
The 24-volt, 40 VA transformer is sized for the furnace components
only, and should not be connected to power auxiliary devices such as
humidifiers, air cleaners, etc. The transformer may provide power for an
air conditioning unit contactor.
For additional connection diagrams for all UPG equipment refer to “Low
Voltage System Wiring” document available online at www.upgnet.com
in the Product Catalog Section.
FIGURE 8: Electrical Wiring
BLK/BLK
WHT/WHT
GRN/GRN
HUM
EAC
L1
(HOT)
NGND
HUM (HOT)
EAC (HOT)
GRN
WHT
BLK
JUNCTION
BOX
DOOR SWITCH
CLASS 2 SYSTEM
CONTROL WIRING
TO THERMOSTAT
WIRING INSIDE
JUNCTION BOX
BURNER
COMPARTMENT
BLOWER
COMPARTMENT
IGNITION
MODULE
Set the heat anticipator in the room thermostat as shown below. Set-
ting it lower will cause short cycles. Setting it higher will cause the
room temperature to exceed the setpoint.
Two-Stage Thermostat First Stage .4 Amps
Second Stage .6 Amps
Single Stage Thermostat .4 Amps
Do not exceed 1.0 amp loading.

272312-UIM-A-0407
12 Unitary Products Group
FIGURE 9: Thermostat Chart - AC
AC9 2 Stage Scroll A/C w/2 Stage Furnace, 2 Stage Cooling Ready- PT8/9; (F,L)*8/9T, (G,L)*8/9T, XYG8S-U, XYF8S-U / XYF8S-U*L
THERMOSTAT
*DP22U70124
C
24-Volt Common
Thermostat Installer Setup
Number 15 - Compressor
Protection - must be set to 5
Y2
Second Stage Cool
W2
Second Stage Heat
R
24-Volt Hot
R
24-Volt Hot
C
24-Volt Common
Y1
First Stage Cool
Y
First Stage Cool
C
24-Volt Common
R
24-Volt Hot
Y1
First Stage Cool
C
24-Volt Common C
24-Volt Common C
24-Volt Common
Y1
First Stage Cool
Comfort Alert
Interface
24V HUMIDIFIER
(Optional)
R
24-Volt Hot
G
Fan
R
24-Volt Hot
W2
Second Stage Heat
E/W1
First Stage Heat
W
First Stage Heat
W2
Second Stage Heat
Step 1 of Thermostat User
Configuration Menu must be
set to MS 2
Step 16 of Thermostat User
Configuration Menu must be set
to ON to use Comfort Alert
Features
HM
Humidistat
L
Malfunction Light
E/W1
First Stage Heat
G
Fan
G
Fan
Connection of the "C" Termainal,
24-Volt Common, is optional
when used with batteries
Thermostat Installer Setup
Number 1 - System Type -
must be set to 6 -
2 Heat/2 Cool Conventional
R
24-Volt Hot (Heat XFMR)
W2
Second Stage Heat
RC
24-Volt Hot (Cool XFMR)
E/W1
First Stage Heat
G
Fan
*DN22U00124
THERMOSTAT
Y2
Second Stage Cool
Y2
Second Stage Cool
Y
First Stage Cool
Y2
Second Stage Cool Y2
Second Stage Cool
Y/Y2
Single/Second Stage
Cool
Y1
First Stage Cool
Connection of the "C"
Termainal, 24-Volt Common,
is optional when used with
batteries
2 STAGE PSC
FURNACE CONTROL TWO STAGE
AIR CONDITIONING
*DN22C00124 *PP32U71124
THERMOSTAT
*PP32U72124
THERMOSTAT
Step 1 of Thermostat User
Configuration Menu must be set
to MLTI STG
W/W1
Single/First Stage Heat
C
24-Volt Common
THERMOSTAT
*PP32U70124
Thermostat Installer Setup
Number 0170 - System Type -
must be set to 8 - 2 Heat/2 Cool
Multistage Conventional
Y
First Stage Cool
Y2
Second Stage Cool
R
24-Volt Hot (Heat XFMR)
RC
24-Volt Hot (Cool XFMR)
G
Fan
W2
Second Stage Heat
Connection of the "C"
Termainal, 24-Volt Common,
is optional when used with
batteries
E/W1
First Stage Heat
W2
Second Stage Heat
G
Fan
Connection of the "C" Termainal,
24-Volt Common, is optional
when used with batteries

272312-UIM-A-0407
Unitary Products Group 13
FIGURE 10: Thermostat Chart - HP
HP23 Two Stage H/P - H*5B, YZE - w/Two Stage Furnace, 2 Stage Cooling Ready - PT8/9, (F,L)*8/9T, (G,L)*8/9T, XYG8S-U, XYF8S-U / XYF8S-U*L
W/031-01996- Series Demand Control; Hot Heat Pump Mode OR Conventional
Thermostat Installer Setup Number 0210 -
External Fossil Fuel Kit - must be set to 0 -
External Fossil Fuel Kit is Controlling
Heat Pump Backup Heat
Change FFuel Jumper on
Heat Pump to ON
Thermostat Installer Setup Number 0190 -
Reversing Valve (O/B) Operation - must be set to 0
- O/B Terminal Energized in Cooling
Step 1 of Thermostat User
Configuration Menu must be
set to Heat Pump 2
Thermostat Installer Setup Number 0200
- Backup Heat Source - must be set to 1 - Heat
Pump Backup Heat Source is Fossil Fuel
24V HUMIDIFIER
(Optional)
Thermostat Installer Setup Number 0170
- System Type - must be set to
12 - 3 Heat/2 Cool Heat Pump
Selection of GAS/ELEC switch on
thermostat not necessary Step 1 of Thermostat User Configuration
Menu must be set to Heat Pump 2 Set W2 Delay on furnace to OFF
HM
Humidistat BSG
Bonnet Sensor
Bonnet Sensor
(Optional) BS
Bonnet Sensor
W2
Second Stage Auxiliary Heat W2
Second Stage Auxiliary Heat
AUX
Auxiliary Heat E/W1
First Stage Auxiliary Heat E/W1
First Stage Auxiliary Heat W
Auxiliary Heat
Y2
Second Stage Heat/Cool Y2
Second Stage Heat/Cool Y2
Second Stage Heat/Cool Y2
Second Stage Heat/Cool
L
Malfunction Light L
Malfunction Light L
Malfunction Light X/L
Malfunction Light
O/B
Reversing Valve O
Reversing Valve–Energized in Cool O
Reversing Valve–Energized in Cool O
Reversing Valve–Energized in Cool
G
Fan G
Fan G
Fan G
Fan
W1 OUT
First Stage Auxiliary Heat Output
DHM
Dehumidistat W2
Second Stage Heat W2 OUT
Second Stage Auxiliary Heat Output
E
Emergency Heat W/W1
Single/First Stage Heat
Y2 OUT
Second Stage Cool Output
R
24-Volt Hot (Heat XFMR) R
24-Volt Hot R
24-Volt Hot R
24-Volt Hot R
24-Volt Hot
RC
24-Volt Hot (Cool XFMR) Y/Y2
Single/Second Stage Cool
C
24-Volt Common C
24-Volt Common
Y
First Stage Heat/Cool Y1
First Stage Heat/Cool Y1
First Stage Heat/Cool Y1
First Stage Cool Y1
First Stage Heat/Cool
*PP32U72124
C
24-Volt Common C
24-Volt Common C
24-Volt Common
TWO STAGE
HEAT PUMP
*PP32U70124 *DN22H00124 *PP32U71124
THERMOSTAT THERMOSTAT THERMOSTAT PSC-2 STAGE
COOLING READY
FURNACE CONTROL
*DP22U70124

272312-UIM-A-0407
14 Unitary Products Group
ACCESSORY CONNECTIONS
The furnace control will allow power-switching control of various acces-
sories. Refer to Figure 11, for connection details.
ELECTRONIC AIR CLEANER CONNECTION
Two 1/4” (0.64 cm) spade terminals (EAC and NEUTRAL) for electronic
air cleaner connections are located on the control board. The terminals
provide 115 VAC (1.0 amp maximum) during circulating blower opera-
tion.
HUMIDIFIER CONNECTION
Two 1/4” (0.64 cm) spade terminals (HUM and NEUTRAL) for humidi-
fier connections are located on the control board. The terminals provide
115 VAC (1.0 amp maximum) during heating system operation.
TWINNING
In applications where more heating capacity or more airflow capacity is
needed than what one furnace can deliver, twinning can be used to
make two furnaces operate in tandem. When two furnaces are installed
using the same duct system, it is very important that the two furnace cir-
culating air blowers operate in unison. If one blower starts before the
second blower, the duct system will become pressurized and the blower
on the second furnace will turn backwards causing the second furnace
to overheat, resulting in damage to the furnace. Twinning is used to
make two furnaces operate in tandem, using one duct system, one
room thermostat and causing both furnaces to turn on and off simulta-
neously.
NOTE: You can twin two furnaces only if they have the same integrated
control board. Check the part number on the integrated control board.
You cannot twin two furnaces that have different integrated control
board part numbers. If the part numbers of the two integrated control
boards are different they may not communicate with each other so they
will not work in a twinning application.
Twinning Duct System
Twinned furnaces must only be applied on a common duct system. A
single air supply plenum must be used for both furnaces and coil(s).
Separate plenums and supply ducts systems cannot be utilized. A sin-
gle return air plenum, common to both furnaces, must be used. It is
suggested that for upflow models, a return platform be utilized, with bot-
tom air entrance into each furnace. If a side entrance returns system is
used, the common return duct must be divided equally so as to supply
each furnace with an equal amount of return air.
Both furnaces must be identical models in both heating capacity and
CFM capacity. Both furnaces must be operated on the same motor
speed taps (low and high, heating and cooling).
IMPORTANT: When two furnaces are twinned, typical system total air-
flow will be approximately 85% of additive individual furnaces, i.e., two
2000 CFM units will yield a total 3400 CFM.
Gas Piping
Furnace gas supplies must be provided as specified with these instruc-
tions. Since the furnaces are side by side, with no space between, gas
supplies must enter on the right and left respectively. All gas piping
must be in accordance with the national fuel gas code, ANSI Z223.1,
latest edition, and/or all local code or utility requirements.
Single-Wire Twinning
The control in the furnace has the single-wire twinning feature. With this
feature, a single wire is connected between the TWIN terminal on one
furnace board to the TWIN terminal on the second furnace board. The
board then communicates the blower status from one furnace to the
other along this wire. This communication makes the second furnace
blower come on at the same time, and on the same speed, as the first
furnace blower.
Single-wire Twinning Wiring Instructions
Connect the thermostat wiring as shown in the appropriate diagram
below. It is required that two separate relays be used to isolate the
low voltage systems of the two furnaces. This isolation will prevent
the possibility of any safety devices being bypassed in an abnormal lim-
iting condition.
Figure 12 below shows control wiring for two furnaces and one single-
speed A/C using a single-stage heat (1H/1C) thermostat. Figure 13
shows control wiring for two furnaces and one single-speed A/C using a
two-stage heat (2H/1C) thermostat. And Figure 14 shows control wiring
for two furnaces and one two-speed A/C using a two-stage heat, two-
stage cool (2H/2C) thermostat. For other configurations, contact techni-
cal services.
NOTE: The twinned furnaces must be connected to the same leg of the
line voltage to prevent phasing error problems. If this is not done prop-
erly, the furnaces will not operate and the control board LEDs will flash
a rapid red flash to indicate the twinning error.
Using a Single-stage Heat Thermostat with Twinned Two-stage
Furnaces - These furnaces may be twinned using a single-stage (1H)
or two-stage (2H) wall thermostat. When using a 1H thermostat, con-
nect the low-voltage wiring as shown in Figure 12. Place the "W2
Delay" jumper in the same position of both furnace control boards. If
the jumper is left in the "OFF" position, the furnaces will operate only at
low fire.
FIGURE 11: Accessory Connections
Before installing the relay and wiring, disconnect electrical power to
both furnaces. Failure to cut power could result in electrical shock
or equipment damage.
The relay must not be installed in any location where it could be
exposed to water. If the relay has been exposed to water in any
way, it must not be used.
115 VOLT
HUMIDIFER
115 VOLT
ELECTRONIC
AIR CLEANER
EAC HOT
HUM. HOT
BLK
WHT
EAC
HUM
NEUTRALS
SWITCHED
CIRCUITS
BLK
WHT
If a return duct is connected to only one furnace (with a connection
between the two furnaces) an imbalance in the airflow will occur
and the furnace farthest from the return plenum will overheat.

272312-UIM-A-0407
Unitary Products Group 15
Twinning Operation
Heating - On a call for low-stage heat (W1 signal) from the wall thermo-
stat, both furnaces will start the ignition sequence and the burners on
both furnaces will light and run at low fire. After a short delay, both blow-
ers will come on and operate at the low heat speed. On a call for high-
stage heat (W2 signal), both furnaces will operate at high fire and both
blowers will operate at the high cool setting. When the thermostat is sat-
isfied, the burners of both furnaces will shut off and, after the selected
blower delay time, both blowers will shut off at the same time.
Cooling - On a call for cooling (Y1 or Y1+Y2 signal) from the wall ther-
mostat, both furnace blowers will come on at the same time and will run
at the appropriate cooling speed. After the thermostat is satisfied, both
blowers will stay on for 60 seconds and then will shut off at the same
time.
Continuous Fan - On a call for continuous fan (G signal) from the wall
thermostat, both blowers will come on in the selected continuous fan
speed and will stay on until the G signal is removed.
SECTION VI: VENT SYSTEM
VENT SAFETY
This Category I, furnace is designed for residential application. It may
be installed without modification in a basement, garage, equipment
room, alcove, attic or any other indoor location where all required clear-
ance to combustibles and other restrictions are met.
FIGURE 12: Twinning Wiring Diagram - 1H/1C Thermostat
FIGURE 13: Twinning Wiring Diagram - 2H/1C Thermostat
FIGURE 14: Twinning Wiring Diagram - 2H/2C Thermostat
Y/Y2
W/W1
W2
R
G
TWIN
TO A/C
1H/1C THERMOSTAT
WG RY
W2 RELAY
FURNACE 2
TWIN
FURNACE 1
Y1
C
Y/Y2
W/W1
W2
R
G
Y1
C
W1 RELAY
Y/Y2
W/W1
W2
R
G
TWIN
TO A/C
2H/1C THERMOSTAT
W2 G RY
W2 RELAY
FURNACE 2
TWIN
FURNACE 1
Y1
C
Y/Y2
W/W1
W2
R
G
Y1
C
W1 RELAY
W1
Y/Y2
W/W1
W2
R
G
TWIN
TO
TWO-STAGE
A/C 2H/2C THERMOSTAT
W2 G RY1
W2 RELAY
FURNACE 2
TWIN
FURNACE 1
Y1
C
Y/Y2
W/W1
W2
R
G
Y1
C
W1 RELAY
W1 Y2
FIGURE 15: Vent Termination 10 ft. (3.0 m) or less
WALL OR
PARAPET
RIDGE
CHIMNEY
CHIMNEY
3 FT (0.9 m)
MIN.
2 FT (0.6 m)
MIN.
10 FT (3.0 m) OR LESS
FROM RIDGE, WALL,
OR PARAPET
*
*
2 FT (0.6 m)
MIN. 3 FT (0.9 m)
MIN.
CHIMNEY
2 FT (0.6 m)
MIN.
10 FT (3.0 m)
OR LESS
*
10 FT (3.0 m)
OR LESS

272312-UIM-A-0407
16 Unitary Products Group
CATEGORY 1 - 450 F. MAX. VENT TEMP.
The venting system must be installed in accordance with Section 5.3,
Air for Combustion and Ventilation, of the National Fuel Gas Code
Z223.1/NFPA 54 (latest edition), or Sections 7.2, 7.3 or 7.4 of CSA
B149.1, National Gas and Propane Codes (latest edition) or applicable
provisions of the local building code and these instructions.
The furnace shall be connected to any type of B, BW or L vent connec-
tor, and shall be connected to a factory-built or masonry chimney. The
furnace shall not be connected to a chimney flue serving a sepa-
rate appliance designed to burn solid fuel.
The furnace rating plate lists the maximum vent gas temperature. This
temperature must be used to select the appropriate venting materials
and clearances.
It is recommended that the appliance is installed in a location where the
space temperature is 32 °F (0°C) or higher. If the appliance is installed
in a location where the ambient temperature is below 32 °F (0°C), the
combustion by-products could condense causing damage to the appli-
ance heat exchanger.
IMPORTANT: The “VENT SYSTEM” must be installed as specified in
these instructions for Residential and Modular Homes.
This appliance may be common vented with another gas appliance for
residential installations as allowed by the codes and standards listed in
these instructions.
Approved Modular Homes must be vented with an approved roof jack
and may not be common vented with other appliances.
VENTING
Category I venting consists of vertically venting one or more appliances
in B-vent or masonry chimney (as allowed), using single wall metal pipe
or B-vent connectors. Type B-vent system extends in a general vertical
direction and does not contain offsets exceeding 45 degrees. A vent
system having not more than one 60 degree offset is permitted.
The vent system must be attached to the flue collar with a minimum of
two (2) mechanical fasteners, such as screws or rivets. See Figure 21.
FIGURE 16: Vent Termination more than 10 ft. (3.0 m)
FIGURE 17: Vent Termination
MORE THAN
10 FT (3.0 m)
3 FT (0.9 m)
MIN.
WALL OR
PARAPET
RIDGE
CHIMNEY
CHIMNEY
3 FT (0.9 m)
MIN.
2 FT (0.6 m)
MIN.
MORE THAN
10 FT (3.0 m)
NOTE: NO
HEIGHT ABOVE
PARAPET REQUIRED
WHEN DISTANCE
FROM WALLS OR
PARAPET IS MORE
THAN 10 FT (3.0 m).
10 FT
(3.0 m)
HEIGHT ABOVE ANY
ROOF SURFACE WITHIN
10 FT (3.0 m) HORIZONTALLY
MORE THAN 10 FT (3.0 m)
FROM RIDGE, WALL,
OR PARAPET
*
*
*
LISTED CAP
LISTED GAS
VENT
LOWEST DISCHARGE OPENING
12
ROOF PITCH
IS x/12
H(min.) MINIMUM HEIGHT
FROM ROOF TO LOWEST
DISCHARGE OPENING
X
TABLE 9: Roof Pitch
ROOF PITCH H(min) ft m
Flat to 6/12 1.0 0.30
6/12 to 7/12 1.25 0.38
Over 7/12 to 8/12 1.5 0.46
Over 8/12 to 9/12 2.0 0.61
Over 9/12 to 10/12 2.5 0.76
Over 10/12 to 11/12 3.25 0.99
Over 11/12 to 12/12 4.0 1.22
Over 12/12 to 14/12 5.0 1.52
Over 14/12 to 16/12 6.0 1.83
Over 16/12 to 18/12 7.0 2.13
Over 18/12 to 20/12 7.5 2.27
Over 20/12 to 21/12 8.0 2.44

272312-UIM-A-0407
Unitary Products Group 17
VENTING INTO AN EXISTING CHIMNEY
For Category I installations, the furnace shall be connected to a factory
built chimney or vent complying with a recognized standard, or a
masonry or concrete chimney lined with a material acceptable to the
authority having jurisdiction. Venting into an unlined masonry chimney
or concrete chimney is prohibited.
Whenever possible, B-1 metal pipe should be used for venting. Where
use of an existing chimney is unavoidable, the following rules must be
followed:
1. The masonry chimney must be built and installed in accordance
with nationally recognized building codes or standards and must
be lined with approved fire clay tile flue liners or other approved
liner material that will resist corrosion, softening, or cracking from
flue gases. THIS FURNACE IS NOT TO BE VENTED INTO AN
UNLINED MASONRY CHIMNEY.
2. This furnace must be vented into a fire clay tile lined masonry
chimney only if a source of dilution air is provided, such as by com-
mon venting with a draft hood equipped water heater. If no source
of dilution air is available, Type B vent must be used, or masonry
chimney vent kit 1CK0603 or 1CK0604 must be used. Refer to the
instructions with the kit to properly apply these masonry chimney
kits.
3. The chimney must extend at least three (3) ft (0.91 cm) above the
highest point where it passes through a roof of a building and at
least two (2) feet higher than any portion of the building with a hor-
izontal distance of ten (10) feet.
4. The chimney must extend at least five (5) ft (1.5 cm) above the
highest equipment draft hood or flue collar.
HORIZONTAL SIDEWALL VENTING
For applications where vertical venting is not possible, the only
approved method of horizontal venting is the use of an auxiliary power
vent. Approved power venters are Fields Controls Model SWG-4Y or
the appropriate Tjernlund GPAK model. Follow all application and
installation details provided by the manufacturer of the power vent. This
unit may be horizontally vented using 4” (10.2 cm) diameter pipe with a
minimum length of 4.5 feet (1.37 m) and a maximum length of 34.5 feet
(10.82 m) with up to 4 elbows.
VENT CLEARANCES
IMPORTANT: The vent must be installed with the following minimum
clearances as shown in Figure 20, and must comply with local codes
and requirements.
FIGURE 18: Typical Sidewall Vent Application
FIGURE 19: Typical Sidewall Vent and Termination Configuration
FAN ASSISTED FURNACE
& WATER HEATER
FAN ASSISTED
FURNACES
VENT
PIPE
HOT
WATER
TANK
OPTIONAL
SIDEWALL
VENT SYSTEM
(field supplied)
EXTERIOR
VENT HOOD
FURNACE FURNACE
VENT PIPE
FLUE
PIPE
BURNER
ACCESS
PANEL
CELLAR
WALL
OPTIONAL
SIDEWALL
VENT SYSTEM
(field supplied)
TOP
COVER
BAROMETRIC
DAMPER

272312-UIM-A-0407
18 Unitary Products Group
† A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwellings and serves both dwellings.
‡ Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the floor. For clearance not specified in ANSI Z223.1 / NFPA
54 or CSA B149.1-00.
Clearance in accordance with local installation codes and the requirements of the gas supplier and the manufacturer’s Installation Manual.
Any fresh air or make up inlet for dryer or furnace area is considered to be forced air inlet.
Avoid areas where condensate drippage may cause problems such as above planters, patios, or adjacent to windows where steam may cause fogging.
A terminus of a vent shall be either:
Fitted with a cap in accordance with the vent manufacturer’s installation instructions, or In accordance with the installation instructions for a special venting system.
* Does not apply to multiple installations of this furnace model. Refer to "VENTING MULTIPLE UNITS" in this section of these instructions.
IMPORTANT: Consideration must be given for degradation of building materials by flue gases. Sidewall termination may require sealing or shielding of building surfaces
with a corrosion resistant material to protect against combustion product corrosion. Consideration must be given to wind direction in order to prevent flue products and/
or condensate from being blown against the building surfaces. If a metal shield is used it must be a stainless steel material at a minimum dimension of 20 inches. It is
recommended that a retaining type collar be used that is attached to the building surface to prevent movement of the vent pipe.
Responsibility for the provision of proper adequate venting and air supply for application shall rest with the installer.
Vent shall extend high enough above building, or a neighboring obstruction, so that wind from any direction will not create a positive pressure in the vicinity of the vent.
HORIZONTAL VENT APPLICATIONS AND
TERMINATION
When selecting the location for a horizontal combustion air / vent termi-
nation, the following should be considered:
1. Observe all clearances listed in vent clearances in these instruc-
tions.
2. Termination should be positioned where vent vapors will not dam-
age plants or shrubs or air conditioning equipment.
3. Termination should be located where it will not be affected by wind
gusts, light snow, airborne leaves or allow recirculation of flue
gases.
4. Termination should be located where it will not be damaged or
exposed to flying stones, balls, etc.
5. Termination should be positioned where vent vapors are not objec-
tionable.
6. Horizontal portions of the vent system must slope upwards and be
supported to prevent sagging. The vent system may be supported
by the use of clamps or hangers secured to a permanent part of
the structure every 4 ft. (1.22 m).
FIGURE 20: Home Layout
L
E
D
B
V
V
VX
V
B
V
J
X
B
B
B
V
V
F
V
C
B
X
V
I
V
G
H
A
M
K
OPERABLE
FIXED
CLOSED
VENT TERMINAL
AIR SUPPLY
AREA WHERE TERMINAL IS NOT PERMITTED
FIXED
CLOSED
Canadian Installations1US Installation2
A. Clearance above grade, veranda, porch, deck, or balcony 12 inches (30 cm) 12 inches (30 cm)
B. Clearance to window or door that may be opened 12 inches (30 cm) for models <100,000 BTUH (30 kW), 36 inches (91 cm) for
models > 100,000 BTUH (30 kW) 4 Feet (1.22 m)
C. Clearance to permanently closed window 12 inches (30 cm) 12 inches (30 cm)
D. Vertical clearance to ventilated soffit located
above the terminal within a horizontal distance
of 2 feet (61 cm) from the center line of the terminal 4 Feet (1.22 m) 4 Feet (1.22 m)
E. Clearance to unventilated soffit 12 Inches (30 cm) 12 Inches (30 cm)
F. Clearance to outside corner 12 Inches (30 cm) 12 Inches (30 cm)
G. Clearance to inside corner 6 Feet (1.83 m) 6 Feet (1.83 m)
H. Clearance to each side of center line extended
above meter/regulator assembly
3 feet (0.91 m) within a height
15 feet (4.57 m) above the
meter/regulator assembly
3 feet (0.91 m) within a height
15 feet (4.57 m) above the
meter/regulator assembly
I. Clearance to service regulator vent outlet 3 feet (0.91 m) 3 feet (0.91 m)
J. Clearance to nonmechanical air supply inlet to
building or the combustion air inlet to any other appliance
12 inches (30 cm) for models <100,000
BTUH (30 kW), 35 inches (91 cm) for
models >100,000 BTUH (30 kW) 4 Feet (1.22 m)
K. Clearance to a mechanical supply inlet 6 feet (1.83 m) 3 feet (0.91 m) above if within
10 feet (3.04 m) horizontally
L. Clearance above paved sidewalk or paved
driveway located on public property 7 feet (2.13 m) †7 feet (2.13 m) †
M. Clearance under veranda, porch, deck, or balcony 12 inches (30 cm) 12 inches (30 cm)
Vent Termination from any Building Surface 12 inches (30 cm) 12 inches (30 cm)
Above anticipated snow depth 12 inches (30 cm) 12 inches (30 cm)
1. In accordance with the current CSA B149.1-00, Natural Gas and Propane Installation Code.
2. In accordance with the current ANSI Z223.1 / NFPA 54, National Gas Code.

272312-UIM-A-0407
Unitary Products Group 19
FAN-ASSISTED COMBUSTION SYSTEM
An appliance equipped with an integral mechanical means to either
draw or force products of combustion through the combustion chamber
and/or heat exchanger.
Ambient Combustion Air Supply
This type installation will draw the air required for combustion from
within the space surrounding the appliance and from areas or rooms
adjacent to the space surrounding the appliance. This may be from
within the space in a non-confined location or it may be brought into the
furnace area from outdoors through permanent openings or ducts. A
single, properly sized pipe from the furnace vent connector to the out-
doors must be provided. For upflow models combustion air is brought
into the furnace through the unit top panel opening.
An unconfined space is not less than 50 cu.ft (1.42 m3) per 1,000 Btu/
hr (0.2928 kW) input rating for all of the appliances installed in that
area.
Rooms communicating directly with the space containing the appli-
ances are considered part of the unconfined space, if openings are fur-
nished with doors.
A confined space is an area with less than 50 cu.ft (1.42 m3) per 1,000
Btu/hr (0.2928 kW) input rating for all of the appliances installed in that
area. The following must be considered to obtain proper air for combus-
tion and ventilation in confined spaces.
Combustion Air Source From Outdoors
The blocking effects of louvers, grilles and screens must be given con-
sideration in calculating free area. If the free area of a specific louver or
grille is not known, refer to Table 10, to estimate free area.
* Do not use less than 1/4”(0.635 cm) mesh
+ Free area of louvers and grille varies widely; the installer should follow lou-
ver or grille
manufacturer’s instructions.
Dampers, Louvers and Grilles (Canada Only)
1. The free area of a supply air opening shall be calculated by sub-
tracting the blockage area of all fixed louvers grilles or screens
from the gross area of the opening.
2. Apertures in a fixed louver, a grille, or screen shall have no dimen-
sion smaller than 0.25” (0.64 cm).
3. A manually operated damper or manually adjustable louvers are
not permitted for use.
4. A automatically operated damper or automatically adjustable lou-
vers shall be interlocked so that the main burner cannot operate
unless either the damper or the louver is in the fully open position.
FIGURE 21: Combustion Airflow Path Through The Furnace Casing to
the Burner Box
This type of installation requires that the supply air to the appli-
ance(s) be of a sufficient amount to support all of the appliance(s)
in the area. Operation of a mechanical exhaust, such as an exhaust
fan, kitchen ventilation system, clothes dryer or fireplace may cre-
ate conditions requiring special attention to avoid unsatisfactory
operation of gas appliances. A venting problem or a lack of supply
air will result in a hazardous condition, which can cause the appli-
ance to soot and generate dangerous levels of CARBON MONOX-
IDE, which can lead to serious injury, property damage and / or
death.
COMBUSTION AIR ATTACH VENT PIPE
TO FLUE COLLAR
JUST ABOVE TOP
PANEL WITH TWO
SCREWS FIGURE 22: Alternate Air Intake, Air Outlet and Chimney Connections
FIGURE 23: Air Inlet, Outlet and Chimney Connections
TABLE 10:
Estimated Free Area
Wood or Metal
Louvers or Grilles Wood 20-25%* Metal 60-70% *
Screens+ 1/4” (0.635 cm)
mesh or larger 100%
FURNACE
WATER
HEATER
OUTLET
AIR
VENTILATION LOUVERS
(each end of attic)
CHIMNEY OR
GAS VENT
INLET
AIR
ALTERNATE
AIR INLET
VENTILATION LOUVERS FOR UNHEATED CRAWL SPACE
FURNACE
WATER
HEATER
OUTLET
AIR
VENTILATION LOUVERS
(each end of attic)
CHIMNEY OR
GAS VENT
INLET AIR DUCT
[ends 1 ft (30 cm)
above floor]

272312-UIM-A-0407
20 Unitary Products Group
FIGURE 24: Typical Chimney Connections
FIGURE 25: Horizontal Air Inlet, Outlet and Chimney Connections
FURNACE
WATER
HEATER
CHIMNEY OR
GAS VENT
OPENING
OPENING
FURNACE
WATER
HEATER
OUTLET
AIR DUCT
INLET
AIR DUCT
When a Category I furnace is removed or replaced, the original
venting system may no longer be correctly sized to properly vent
the attached appliances.
An improperly sized vent system can cause CARBON MONOXIDE
to spill into the living space causing personal injury, and or death.
TABLE 11:
Free Area
Combined
BTUH Input
Rating For
All Appliances
Minimum Free Area Required for Each Opening
Horizontal Duct
(2,000 BTUH /
Sq. In.)
Vertical Duct or
Opening to Outside
(4,000 BTUH /
Sq. In.)
Round Duct
(4,000 BTUH /
Sq. In.)
40,000 20 in2(129 cm2) 10 in2(64 cm2)4” (10 cm)
60,000 30 in2(193 cm2) 15 in2(97 cm2)5” (13 cm)
80,000 40 in2(258 cm2) 20 in2(129 cm2)5” (13 cm)
100,000 50 in2(322 cm2) 25 in2(161 cm2)6” (15 cm)
120,000 60 in2(387 cm2) 30 in2(193 cm2)7” (18 cm)
EXAMPLE: Determining Free Area - Vertical Minimum Duct Size
Appliance 1 Appliance 2 Total Input
100,000 + 30,000 = 130,000 ÷4,000 = 32.5 Sq. In.
EXAMPLE: Determining Free Area - Horizontal Minimum Duct Size
Appliance 1 Appliance 2 Total Input
100,000 + 30,000 = 130,000 ÷2,000 = 65 Sq. In.
TABLE 12:
Unconfined Space Minimum Area in Square Inch
BTUH Input Rating Minimum Free Area in Square Feet
Required for Each Opening
40,000 40 (258 cm2)
60,000 60 (387 cm2)
80,000 80 (516 cm2)
100,000 100 (645 cm2)
120,000 120 (774 cm2)
FIGURE 26: Outside and Ambient Combustion Air
GABLE
VENT
GAS
VENT
SOFFIT
VENT
VENTILATED
ATTIC
TOP ABOVE
INSULATION
OPTIONAL
INLET (a)
OUTLET
AIR (a)
VENTILATED
CRAWL SPACE
GAS
WATER
HEATER
VENTILATED
ATTIC
TOP ABOVE
INSULATION
GAS
VENT
GABLE
VENT
SOFFIT
VENT
GAS
WATER
HEATER INLET
AIR (a)
INLET
AIR (b)
GAS
VENT
OUTLET
AIR (a)
OUTLET
AIR (b)
INLET
AIR (a)
INLET
AIR (b)
GAS
WATER
HEATER
FURNACE
FURNACE
FURNACE
1. An opening maybe used in lieu of a duct to provide to provide the outside air
supplyto an appliance unless otherwise permitted bythe authorityhaving
jurisdiction. The opening shall be located within 12” (30.5 cm) horizontallyfrom,
the burner level of the appliance. Refer to “COMBUSTION AIR SOURCE FROM
OUTDOORS and VENT AND SUPPLY AIR SAFETY CHECK” in these
instructions for additional information and safetycheck procedure.
2. The duct shall be either metal, or a material meeting the class 1
requirements of CAN4-S110 Standard for Air Ducts.
3. The duct shall be least the same cross-sectional area as the free
area of the air supplyinlet opening to which it connects.
4. The duct shall terminate within 12 in (30.5 cm) above, and
within 24 in (61 cm) horizontallyfrom, the burner level of
the appliance having the largest input.
5. A square or rectangular shaped duct shall onlybe used
when the required free area of the supplyopening is
9 in (58.06 cm ) or larger. When a square or rectangular
duct is used, its small dimensionshall not be less than
3 in (7.6 cm).
22
6. An air inlet supplyfrom outdoors shall be equipped with
a means to prevent the direct entryof rain and wind.
Such means shall not reduce the required free area of
the air supplyopening.
7. An air supplyinlet opening from the outdoors shall
be located not less than 12” (30.5 cm) above the
outside grade level.
AIR SUPPLY OPENINGS AND DUCTS
COMBUSTION AIR SOURCE FROM OUTDOORS
1. Two permanent openings, one within 12 in (30.5 mm) of the top and
one within 12 in (30.5 mm) of bottom of the confined space,
shall communicate directlyor bymeans of ducts
with the outdoors, crawl spaces or attic spaces.
Two
permanent openings,
2. One permanent openings, commencing within 12 in (30.5 mm)of the
top of the enclosure shall be permitted where the equipment has
clearances of at least 1 in (2.54 cm) from the sides and back and
6 in (15.24 cm) from the front of the appliance. The opening shall
communicate directlywith the outdoors and shall have a minimum
free area of:
3. The duct shall be least the same cross-sectional area as the free
area of the air supplyinlet opening to which it connects.
1 square in per 3000 Btu per hour (6.45 cm 0.879 kW) of the
total input rating of all equipment located in the enclosure.
3
per
a.
Not less than the sum of all vent connectors in the confined space.
b.
4. The blocking effects of louvers, grilles and screens must be given
consideration in calculating free area. If the free area of a specific
louver aor grille is not known.