Unitary products group PV8*UH, FC8V*UH, FL8V*UH, LC8V*UH, LL8V*UH Installation Manual
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INSTALLATION MANUAL
HIGH EFFICIENCY
TUBULAR HEAT EXCHANGER SERIES
MODELS: PV8*UH/FC8V*UH/FL8V*UH/LC8V*UH/LL8V*UH
(Two Stage Variable Speed Upflow / Horizontal / Low NOx)
57 - 120 MBH INPUT
(16.7 - 35.2 KW) INPUT
LIST OF SECTIONS
SAFETY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
DUCTWORK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
FILTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
GAS PIPING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
ELECTRICAL POWER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
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
Vent Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Vent Termination 10 ft. (3.0 m) or less . . . . . . . . . . . . . . . . . . . . . . . .14
Vent Termination more than 10 ft. (3.0 m) . . . . . . . . . . . . . . . . . . . . .14
VENT SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
SAFETY CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
START-UP AND ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . .20
WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Typical Sidewall Vent Application . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Typical Sidewall Vent and Termination Configuration . . . . . . . . . . . .15
Home Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Combustion Airflow Path Through The Furnace . . . . . . . . . . . . . . . . .17
Alternate Air Intake, Air Outlet and Chimney Connections . . . . . . . . .17
Air Inlet, Outlet and Chimney Connections . . . . . . . . . . . . . . . . . . . . .17
Typical Chimney Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Horizontal Air Inlet, Outlet and Chimney Connections . . . . . . . . . . . .18
Outside and Ambient Combustion Air . . . . . . . . . . . . . . . . . . . . . . . . .18
Pressure Switch Tubing Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Gas Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Reading Gas Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Furnace Control Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
EFFICIENCY
RATING
CERTIFIED
ISO 9001
Certified Quality
Management System
LIST OF TABLES
Unit Clearances to Combustibles . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Minimum Duct Sizing For Proper Airflow . . . . . . . . . . . . . . . . . . . . . . . 5
Round Duct Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Cabinet and Duct Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Filter Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Nominal Manifold Pressure - High Fire . . . . . . . . . . . . . . . . . . . . . . . .9
Nominal Manifold Pressure - Low Fire . . . . . . . . . . . . . . . . . . . . . . . . . 9
Ratings & Physical / Electrical Data . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Roof Pitch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
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 mo derate injury.
alert against unsafe practices and hazards involving only property damage.
.
.
It is also used to
Estimated Free Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Free Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Unconfined Space Minimum Area in Square Inch . . . . . . . . . . . . . . .18
Inlet Gas Pressure Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Nominal Manifold Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Filter Performance - Pressure Drop Inches W.C. and (kPa) . . . . . . . .25
Air Flow Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Field Installed Accessories - Non Electrical . . . . . . . . . . . . . . . . . . . .27
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 maintenance can cause injury or property damage. Refer to this manual
for assistance or for additional information, consult a qualified contractor, installer or service agency.
This product must be installed in strict compliance with the installation instructions and any applicable local, state, and national codes
including, but not limited to building, electrical, and mechanical
codes.
271001-UIM-A-0407
271001-UIM-A-0407
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 SECTION VI of these instructions.
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 property damage, personal injury or loss of life.
6. Test for gas leaks as specified in SECTION VIII of these instructions.
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 furnace casing and terminating outside the space containing the furnace.
9. It is permitted to use the furnace for heating of buildings or structures under construction. Installation must comply with all manufacturer’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 furnaceoperating 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 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 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 plenum 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
into a Manufactured (Mobile) Home
• This furnace is not approved for installation in trailers or recreational 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 electrical characteristics match. All models use nominal 115 VAC, 1
Phase, 60-Hertz power supply. DO NOT CONNECT THIS APPLIANCE TO A 50 HZ POWER SUPPLY OR A VOLTAGE ABOVE
130 VOLTS.
• Furnace shall be installed so the electrical components are protected 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 precautions 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.
CSA listed or approved for installation
.
COMBUSTION AIR QUALITY
(LIST OF CONTAMINANTS)
The furnace will require OUTDOOR AIR for combustion when the furnace 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 furnace is located in an area where the furnace is being exposed to the following 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.
2 Unitary Products Group
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 furnace.
1. Spray or aerosol cans, rags, brooms, dust mops, vacuum
cleaners or other cleaning tools.
2. Soap powders, bleaches, waxes or other cleaning compounds; plastic items or containers; gasoline, kerosene, cigarette 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 COMMONWEALTH 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 residential purposes, including those owned or operated by the Commonwealth 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 requirements 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 monoxide detector with an alarm shall be installed.
2. APPROVED CARBON MONOXIDE DETECTORS. Each carbon 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 permanently 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 OBSTRUCTIONS".
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 carbon monoxide detectors and signage installed in accordance
with the provisions of 248 CMR 5.08(2)(a)1 through 4.
271001-UIM-A-0407
INSPECTION
As soon as a unit is received, it should be inspected for possib le damage 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.
Installation in freezing temperatures:
1. Furnace shall be installed in an area where ventilation facilities
provide for safe limits of ambient temperature under normal operating 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.
Improper installation in an ambient below 32ºF (0.0° C) could create
a hazard, resulting in damage, injury or death.
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 clearances 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.
Unitary Products Group 3
271001-UIM-A-0407
TABLE 1:
1. Special floor base or air conditioning coil required for use on combust i ble floor.
2. 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
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
2. Be installed in accordance with standards of NFPA (National Fire
3. Create a closed duct system. For residential and Modular Home
4. Complete a path for heated or cooled air to circulate through the
Unit Clearances to Combustibles
Application
Top Front Rear Left Side Right Side Flue
In. (cm) In. (cm) In. (cm) In. (cm) In. (cm) In. (cm)
Downflow 1 (2.5 6 (15.2) 0 (0.0) 0 (0.0) 3 (7.6) 6 (15.2)
Downflow B-Vent 1 (2.5) 3 (7.6) 0 (0.0) 0 (0.0) 0 (0.0) 1 (2.5)
Floor/
Bottom
1 (2.5)
1 (2.5)
Closet Alcove Attic
1
1
Yes Yes Yes No
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
Horizontal B-Vent 1 (2.5) 3 (7.6) 0 (0.0) 0 (0.0) 0 (0.0) 1 (2.5) Combustible No Yes Yes
joists, studs or framing.
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 operating parameters of the furnace specifications.
Protection Association) as outlined in NFPA pamphlets 90A and
90B (latest editions) or applicable national, provincial, or state, and
local fire and safety codes.
installations, when a furnace is installed so that the supply 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.
air conditioning and heating equipment and to and from the conditioned space.
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 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
Line
Contact
Yes
Yes
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 cooling coil must be installed in the supply air duct, downstream of the furnace. Cooled air may not be passed over the heat
exchanger.
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 prevent the furnace or the air conditioner from operating unless the damper
is in full heat or cool position.
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 furnace operation.
Use the Example below to help you in calculating the duct area to determine whether the ducts have sufficient area so that the furnace operates 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
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 pressures 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.
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 pressure and within the air temperature rise specified on the nameplate,
providing the return duct is properly sized as well.
2
2
4 Unitary Products Group
271001-UIM-A-0407
TABLE 2:
Minimum Duct Sizing For Proper Airflow
Airflow
Return
1
Rectangular
2
Round
2
Supply
3
Rectangular
2
Round
CFM (m³) 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 (cm
2
)
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)
IMPORTANT: The minimum plenum height is 12” (30.5 cm). The furnace will not operate properly on a shorter plenum height. The minimum 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 filter box or an electronic air cleaner is installed, take the return air readings before the filter box or air cleaner.
10 (25) 78.5 (506)
11 (28) 95 (613)
12 (30) 113.1 (730)
13 (33) 132.7 (856)
14 (36) 153.9 (993)
1. The Air Temperature Rise is determined by subtracting the Return
Air Temperature Reading from the Supply Air Temperature Reading.
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 and 3 are 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 and 3 ARE 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
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 information on correcting the problem.
If a matching cooling coil is used, it may be placed directly on the furnace 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 indicate the presence of leaks in the heat exchanger. This access cover
shall be attached in such a manner as to prevent leaks.
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.
2
Unitary Products Group 5
271001-UIM-A-0407
B
A
FRONT
1-1/4
3/4
40
26-3/4
BOTTOM IMAGE
RETURN END
20
GAS INLET
1-1/4 x 2-1/2
30-1/8
LEFT SIDE
1-1/2
C
4” DIA. VENT
CONNECTIONS
1-1/4
D
4” Diameter
(VENT CONNECTIONS)
POWER WIRING
7/8” HOLE
ACCESS
WIRING
7/8” K.O.
T’STAT
WIRING
7/8” K.O.
20
24-3/4
TOP IMAGE
SUPPLY END
5/8
GAS INLET
1-1/4 x 2-1/2
14
RIGHT SIDE
5/8
B
23-1/2
2-1/4
1-1/8
FIGURE 1: Dimensions
TABLE 4:
Cabinet and Duct Dimensions
BTUH Input
MBH kW A A (cm) B B (cm) C C (cm) D D (cm)
CFM (m
3
/min)
Cabinet
Size
Cabinet Dimension
57/42 17.6/12.3 1200 (33.98) A 14 1/2 36.8 13 1/4 33.6 11 1/2 25.7 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 25.7 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 1600 (45.31) 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 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 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 2000 (56.63) C 21 53.3 19 3/4 50.2 18 45.7 13 3/8 34
RESIDENTIAL AND MODULAR HOME UPFLOW
RETURN PLENUM CONNECTION
Return air may enter the furnace through the side(s) or bottom depending 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 recommended those applications over 1800 CFM (57 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 platform 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.
6 Unitary Products Group
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.
271001-UIM-A-0407
Horizontal Installations With a Cooling Coil Cabinet
The furnace should be installed with coil cabinet part number specifically intended for Horizontal application. If a matching cooling coil is
used, it may be placed directly on the furnace outlet and sealed to prevent leakage. Follow the coil instructions for installing the supply plenum. 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 connected 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 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 return plenum to the furnace inlet duct 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. 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 furnace 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
12”
SUPPLY AIR
VENT (Maintain
required clearances
to combustibles)
SHEET METAL
IN FRONT OF
FURNACE
COMBUSTION AIR
OPENINGS IS
RECOMMENDED
LINE CONTACT ONLY PERMISSIBLE
BETWEEN LINES FORMED BY THE
INTERSECTION OF FURNACE TOP
AND TWO SIDES AND BUILDING
JOISTS, STUDS OR FRAMING
FILTER RACK
MUST BE A MINIMUM
DISTANCE
OF 18” (45.7 cm)
FROM THE
FURNACE
RETURN AIR
GAS PIPING
SEDIMENT
TRAP
12”
30” MIN.
WORK AREA
FIGURE 2: Typical 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.
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.
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 suspension 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.
ANGLE IRON
BRACKET
6” MIN. BETWEEN
ROD & FRONT OF FURNACE
1” MAX. BETWEEN
ROD & BACK OF FURNACE
FIGURE 3: Typical Suspended Furnace / Crawl Space Installation
In any application where temperatures below freezing are possible,
see “INSTALLATION IN FREEZING TEMPERA T URES” in Section I
SUPPORT
BRACKET
Unitary Products Group 7
271001-UIM-A-0407
SECTION III: FILTERS
FILTER INSTALLATION
All applications require the use of an internal or external filter. Filter(s)
and the filter retainer are not provided on all models Some models are
shipped with a high velocity filter that must be field installed. A field-supplied external filter and filter retainer hardware must be provided if the
filter and the filter retainer are not shipped with the furnace. Refer to
Table 5 for the recommended filter size.
TABLE 5:
Cabinet Size Side (in) Side (cm) Bottom (in) Bottom (cm)
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.
FIGURE 4: Side Return Cutout Markings
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 instructions 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 (rectangular 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.
Filter Sizes
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
D (2) 16 x 25 (2) 40.6 x 64.0 20 x 25 50.8 x 64.0
FRONT OF
FURNACE
CORNER
MARKINGS
SECTION IV: GAS PIPING
GAS SAFETY
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.
HIGH STAGE REGULATOR
OUTLET
PRESSURE
PORT
INLET
WRENCH
BOSS
INLET
PRESSURE
PORT
FIGURE 5: Gas Valve
IMPORTANT: Plan your gas supply before determining the correct gas
pipe entry. Use 90-degree service elbow(s), or short nipples and conventional 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 connector. 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 furnace 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
and 7.
TO GAS
SUPPLY
ADJUSTMENT
ON OFF
SWITCH
EXTERNAL MANUAL
SHUTOFF VALVE
VENT
PORT
OUTLET
LOW STAGE REGULATOR
ADJUSTMENT
TO GAS
SUPPLY
All installations must have a filter installed.
8 Unitary Products Group
DRIP
LEG
GROUNDED JOINT UNION
MAY BE INSTALLED
INSIDE OR OUTSIDE UNIT.
FIGURE 6: Upflow Gas Piping
271001-UIM-A-0407
MANUAL
SHUT-OFF
GAS
PIPE
VALV E
DRIP
LEG
GAS
PIPE
MANUAL
SHUT-OFF VALVE
DRIP
LEG
GAS BURNERS
GAS VALVE
FIGURE 7: Horizontal Gas Piping
IMPORTANT: An accessible manual shutoff valve must be installed
upstream of the furnace gas controls and within 6 feet (1.8 m) of the furnace.
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).
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 octagonal 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.
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 factory-supplied LP conversion kit. Follow the instructions supplied with
the LP kit. Refer to Table 6 or the instructions in the propane (LP) conversion kit for the proper gas orifice size.
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.
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 maintain 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
Tables 6 and 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 17 Field Installed Accessories - High
Altitude Pressure Switch
TABLE 6:
(BTU/cu ft.)
Gas Heating Value
TABLE 7:
(BTU/cu ft.)
Gas Heating Value
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
800 3.5 3.5 3.5
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
(MJ/cu m)
Gas Heating Value
29.8 0.87 0.87 0.87
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
800 1.7 1.7 1.7
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
(MJ/cu m)
Gas Heating Value
29.8 0.42 0.42 0.42
Unitary Products Group 9
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