Unitary products group GY8S Series User manual

035-20464-002 Rev. A (1004)
EFFICIENCY
RATING
CERTIFIED
This product was manufactured
in a plant whose quality system
is certified/registered as being
in conformity with ISO 9001.
HIGH EFFICIENCY
TUBULAR HEAT EXCHANGER SERIES
MODELS: GY8S / GM8S / LY8S / LM8S / LF8
(Single Stage Upflow / Horizontal / LoNOx)
40 - 130 MBH INPUT
(11.72 - 38.10 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.
TABLE OF CONTENTS
SAFETY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
DUCTWORK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
FILTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
GAS PIPING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
ELECTRICAL POWER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
TWINNING AND STAGING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
VENT SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
SAFETY CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
START-UP AND ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . .19
WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
LIST OF FIGURES
Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Furnace Base Rectangular Perforated Panel . . . . . . . . . . . . . . . . . . .6
Typical Attic Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Typical Suspended Furnace / Crawl Space Installation . . . . . . . . . . . . 7
Side Return Cutout Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Gas Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Upflow Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Horizontal Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Electrical Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Line Wiring Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Heating and Cooling Thermostat Connections . . . . . . . . . . . . . . . . .11
Accessory Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Typical Twinned Furnace Application . . . . . . . . . . . . . . . . . . . . . . . .11
Single Stage Twinning Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . .12
Two-Stage Twinning Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . .13
Vent Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Vent Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Typical Sidewall Vent Application . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Typical Sidewall Vent and Termination Configuration . . . . . . . . . . . .14
Home Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Combustion Airflow Path Through The Furnace Casing to the Burner
Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Alternate Air Intake, Air Outlet and Chimney Connections . . . . . . . . .16
Air Inlet, Outlet and Chimney Connections . . . . . . . . . . . . . . . . . . . . .16
Typical Chimney Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Horizontal Air Inlet, Outlet and Chimney Connections . . . . . . . . . . . .17
Outside and Ambient Combustion Air . . . . . . . . . . . . . . . . . . . . . . . . .17
Pressure Switch Tubing Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Gas Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Reading Gas Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Typical Heat/Cool Speed Tap Connections . . . . . . . . . . . . . . . . . . . .22
Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
LIST OF TABLES
Unit Clearances to Combustibles . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Minimum Duct Sizing For Proper Airflow . . . . . . . . . . . . . . . . . . . . . . .4
Round Duct Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Cabinet and Duct Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Filter Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Inlet Gas Pressure Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
High Altitude Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Ratings & Physical / Electrical Data - Upflow Models . . . . . . . . . . . .10
Roof Pitch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Horizontal Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Estimated Free Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Free Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Unconfined Space Minimum Area in Square Inch . . . . . . . . . . . . . . .17
Inlet Gas Pressure Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Nominal Manifold Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Filter Performance - Pressure Drop Inches W.C. and (kPa) . . . . . . . .22
Blower Performance CFM - Upflow (without filter) - Bottom Return . .23
Blower Performance CFM - Upflow (without filter) - Left Side Return 24

035-20464-002 Rev. A (1004)
2Unitary Products Group
SPECIFIC SAFETY RULES AND PRECAUTIONS
1. Only Natural gas or Propane (LP) gas are approved for use with
this furnace.
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 VII of these instructions.
5. Combustion products must be discharged outdoors. Connect this
furnace to an approved vent system only, as specified in SEC-
TION VII of these instructions.
6. Test for gas leaks as specified in SECTION XI 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. The furnace is not to be used for temporary heating of buildings or
structures under construction.
10. When installed in a Non-HUD-Approved Modular Home or building
constructed on-site, combustion air shall not be supplied from
occupied 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 wastewater 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.
• 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 HUD Approved Modular Home or 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 non-HUD 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
• Antistatic 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.

035-20464-002 Rev. A (1004)
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 VII 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 to provide
proper condensate drainage.
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:
1. 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.
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 Non-HUD Modu-
lar Home installations, when a furnace is installed so that the sup-
ply ducts carry air circulated by the furnace to areas outside the
space containing 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.
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. Improper installation in an ambient below 32ºF (0.0° C) could create
a hazard, resulting in damage, injury or death.
TABLE 1: Unit Clearances to Combustibles
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 (25.4) 6 (15.24) 0 (0.0) 0 (0.0) 3 (7.62)1
1. 14-1/2” cabinet models only. All other units “0” clearance.
6 (15.24) COMBUSTIBLE YES YES YES NO
UPFLOW B-VENT 1 (25.4) 3 (7.62) 0 (0.0) 0 (0.0) 0 (0.0) 1 (25.4) COMBUSTIBLE YES YES YES NO
HORIZONTAL 3 2
2. 14-1/2” cabinet left airflow applications only. All other units and right hand airflow applications “0” clearance.
6 (15.24) 0 (0.0) 1 (25.4) 0 (0.0) 6 (15.24) COMBUSTIBLE NO YES YES YES3
3. 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.
HORIZONTAL B-VENT 0 (0.0) 3 (7.62) 0 (0.0) 1 (25.4) 0 (0.0) 1 (25.4) COMBUSTIBLE NO YES YES YES3

035-20464-002 Rev. A (1004)
4Unitary Products Group
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
Attach the supply plenum to the furnace outlet duct connec-
tion 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. 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.
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. 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 con-
trols may not operate 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.
Ex. The furnace input is 80,000 BTUH and 1,200 CFM. The recom-
mended duct area is 280 sq.in, there are two 8 x 14 rectangular ducts
attached to the plenum and there are two 7 inch round ducts attached to
the furnace.
1. Take 8 x 14, which equals 112 sq.in. X 2, which equals 224 square
inch then go to round duct size located in Table 3.
2. The square inch area for 7 inch round pipe is 38.4, multiply by 2 for
two round ducts which equals 76.8 square inch,
3. Then take the 224 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 plenum is 300.8 square inch. This exceeds
the recommended 280 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.
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, adding the pressure across any applied a-coil and the
drop across the return air filter.
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.
TABLE 2: Minimum Duct Sizing For Proper Airflow
Input Airflow Return1Rectangular2Round2Supply3
BTU/H(kW) CFM(m³) In² (cm²) in. x in.(cm x cm) in. (cm) dia. In²(cm²)
40,000(11.72) 1,200(33.98) 280 (711) 14 x 20 (35.6 x 50.8) 18 (45.7) 216 (549)
60,000 (17.58) 1,200 (33.98) 280 (711) 14 x 20 (35.6 x 50.8) 18 (45.7) 216 (549)
80,000 (23.44) 1,200 (33.98) 280 (711) 14 x 20 (35.6 x 50.8) 18 (45.7) 216 (549)
80,000 (23.44) 1,600 (45.31) 360 (914) 18 x 20 (45.7 x 50.8) 22 (55.8) 280 (711)
80,000 (23.44) 2,000 (56.63) 440 (1,118) 20 x 22 (50.8 x 55.8) 24 (60.9) 390 (991)
100,000 (29.31) 1,200 (33.98) 320 (813) 16 x 20 (40.6 x 50.8) 20 (50.8) 336 (853)
100,000 (29.31) 1,600 (45.31) 360 (914) 18 x 20 (45.7 x 50.8) 22 (55.8)) 280 (711)
100,000 (29.31) 2,000 (56.63) 440 (1,118) 20 x 22 (50.8 x 55.8) 24 (60.9) 390 (991)
115,000 (35.17) 1,600 (45.31) 360 (914) 18 x 20 (45.7 x 50.8) 22 (55.8)) 280 (711)
115,000 (35.17) 2,000 (56.63) 440 (1,118) 20 x 22 (50.8 x 55.8) 24 (60.9) 390 (991)
130,000 (41.03) 2,000 (56.63) 440 (1,118) 20 x 22 (50.8 x 55.8) 24 (60.9) 390 (991)
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 (19.82 m3/ minute).
2. Example return main trunk duct minimum dimensions.
3. Maximum supply air velocity in rigid duct @ 900 feet per minute (25.49 m3/ minute).
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)

035-20464-002 Rev. A (1004)
Unitary Products Group 5
TABLES 2 & 3 is to be used as a guide only to help the installer deter-
mine if the duct sizes are large enough to obtain the proper air flow
(CFM) through the furnace. TABLES 2 & 3 IS NOT to be used to design
ductwork 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.
The supply air temperature MUST NEVER exceed the Maximum
Supply Air Temperature, specified on the nameplate.
Operating the furnace above the maximum supply 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 XI for additional informa-
tion on correcting the problem.
FIGURE 1: Dimensions
All dimensions are in inches and are approximate.
FRONT LEFT SIDE RIGHT SIDE
D
B20
40
A28-1/2
3/4
14-3/4
5-3/8
(VENT CONNECTIONS)
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
20
BC
A
3/4”
FLANGE
BOTTOM IMAGE
(FRONT)
TOP IMAGE
(FRONT)
VENT
CONNECTION
(Vent Size)
D
F
E
28-1/2
23
(WITH K.O.
REMOVED)
TABLE 4: Cabinet and Duct Dimensions
BTUH (kW)
Input/Output CFM (m3/min) Cabinet
Size Cabinet Dimension
A A (cm) B B (cm) C C (cm) D D (cm) F F (cm) E E (cm)
40/32 (11.71/9.38) 1200 (33.98) A 14 1/2 36.8 13 1/4 33.6 10 1/8 25.7 4.0 10.2 10 1/8 25.7 3 3/4 9.5
60/48 (17.6/14.07) 1200 (33.98) A 14 1/2 36.8 13 1/4 33.6 10 1/8 25.7 4.0 10.2 10 1/8 25.7 3 3/4 9.5
80/64 (23.42/18.76) 1200 (33.98) A 14 1/2 36.8 13 1/4 33.6 10 1/8 25.7 4.0 10.2 10 1/8 25.7 33/4 9.5
80/64 (23.42/18.76) 1600 (45.31) B 17 1/2 44.4 16 1/4 41.3 13 1/8 33.3 4.0 10.2 11 5/8 29.5 3 3/4 9.5
80/64 (23.42/18.76) 2200 (62.30) C 21 53.3 19 3/4 50.2 16 5/8 42.2 4.0 10.2 13 3/8 34 3 3/4 9.5
100/80 (29.28/23.42) 1200 (33.98) B 171/2 44.4 16 1/4 41.3 13 1/8 33.3 4.0 10.2 11 5/8 29.5 33/4 9.5
100/80 (29.28/23.42) 1600 (45.31) B 171/2 44.4 16 1/4 41.3 13 1/8 33.3 4.0 10.2 11 5/8 29.5 33/4 9.5
100/80 (29.28/23.42) 2000 (56.63) C 21 53.3 19 3/4 50.2 16 5/8 42.2 4.0 10.2 13 3/8 34 3 3/4 9.5
115/92 (33.70/26.96) 1600 (45.31) C 21 53.3 19 3/4 50.2 16 5/8 42.2 4.0 10.2 13 3/8 34 3 3/4 9.5
115/92 (33.70/26.96) 2000 (56.63) C 21 53.3 19 3/4 50.2 16 5/8 42.2 4.0 10.2 13 3/8 34 3 3/4 9.5
130/104 (38.09/30.48) 2000 (56.63) D 24 1/2 62.2 23 1/4 59.1 20 1/8 51.1 4.0 10.2 15 1/8 27.6 3 3/4 9.5