
2
Contents
TABLE OF CONTENTS
1 TABLE OF CONTENTS. . . . . . . . . . . . . . . . . . . . . . . 2
2 GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . 3
Receiving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
California Proposition 65 Note . . . . . . . . . . . . . . . . . . 4
Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 SAFETY INFORMATION. . . . . . . . . . . . . . . . . . . . . . 6
Warnings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Important Information About Ef ficiency and Quality. . 7
4 LOCATION REQUIREMENTS . . . . . . . . . . . . . . . . . 8
Site Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Clearance –Accessibility . . . . . . . . . . . . . . . . . . . . . . 8
Upflow Dimensions and Clearance Table . . . . . . . . . 9
5 DUCTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Upflow Installations. . . . . . . . . . . . . . . . . . . . . . . . . . 11
Horizontal Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6 COMBUSTION AND VENTILA TION AIR. . . . . . . . 14
Combustion Air Requirements. . . . . . . . . . . . . . . . . 14
Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
“B-1” Vertical Venting . . . . . . . . . . . . . . . . . . . . . . . . 19
Special Vent Systems (SVS) . . . . . . . . . . . . . . . . . . 20
Power Vent Systems . . . . . . . . . . . . . . . . . . . . . . . . 22
Existing Vent Systems . . . . . . . . . . . . . . . . . . . . . . . 22
7 GAS SUPPLY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Gas Supply and Piping. . . . . . . . . . . . . . . . . . . . . . . 23
Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Gas Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Setting Gas Pressure . . . . . . . . . . . . . . . . . . . . . . . . 26
Supply Gas Pressure Measurement . . . . . . . . . . . . 26
Manifold Gas Pressure Measurement. . . . . . . . . . . 26
8 LP CONVERSION . . . . . . . . . . . . . . . . . . . . . . . . . . 27
9 ELECTRICAL WIRING . . . . . . . . . . . . . . . . . . . . . . 28
Reversing The Electrical Connection. . . . . . . . . . . . 28
Thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
10 ACCESSORIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Field Installed Option Accessories. . . . . . . . . . . . . . 30
Electronic Air Cleaner. . . . . . . . . . . . . . . . . . . . . . . . 30
Humidifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
RXGW-B01 Chimney Adapter . . . . . . . . . . . . . . . . . 30
RXGW-C01 Four Inch Flue Adapter . . . . . . . . . . . . 30
11 TWINNING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Furnace T winning Installations. . . . . . . . . . . . . . . . . 32
Control Boards . . . . . . . . . . . . . . . . . . . . . . . . . . 33-34
12 HIGH ALTITUDE . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Natural Gas at High Altitudes. . . . . . . . . . . . . . . . . . 35
LP Gas at High Altitudes. . . . . . . . . . . . . . . . . . . . . . 37
13 STARTUP PR OCEDURES . . . . . . . . . . . . . . . . . . . 38
Sequence of Operation . . . . . . . . . . . . . . . . . . . . . . 38
14 DIAGNOSTICS AND F AULT CODES. . . . . . . . . . . 39
15 LOCKOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
16 FIELD SELECTIONS & ADJUSTMENTS . . . . . . . 41
Field Selections – Dipswitches. . . . . . . . . . . . . . . . . 41
17 FA ULT CLEAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
18 FA ULT RECALL. . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
19 FLAME STATUS L.E.D.. . . . . . . . . . . . . . . . . . . . . . 42
20 TIMING DIAGRAM. . . . . . . . . . . . . . . . . . . . . . . . . . 42
21 ADJUSTING OR CHECKING FURNACE INPUT . 43
22 SETTING INPUT RATE. . . . . . . . . . . . . . . . . . . . . . 44
23 AIRFLOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Blower Speed Selection. . . . . . . . . . . . . . . . . . . . . . 46
24 SAFETY FEATURES. . . . . . . . . . . . . . . . . . . . . . . . 47
25 MAINTENANCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
26 SYSTEM OPERATION INFORMATION . . . . . . . . . 49
27 ANNUAL INSPECTION. . . . . . . . . . . . . . . . . . . . . . 49
28 REPLACEMENT P AR TS. . . . . . . . . . . . . . . . . . . . . 49
24 TROUBLESHOOTING. . . . . . . . . . . . . . . . . . . . . . . 50
30 WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . 51
IMPORTANT: TO INSURE PROPER INSTALLATION AND OPERATION OF THIS PRODUCT, COMPLETELY READ ALL INSTRUC-
TIONS PRIOR TO ATTEMPTING TO ASSEMBLE, INSTALL, OPERATE, MAINTAIN OR REP AIR THIS PRODUCT. UPON UNPACKING
OF THE FURNA CE, INSPECT ALL PARTS FOR DAMAGE PRIOR TO INSTALLATION AND START-UP.

3
General Information
GENERAL INFORMATION
NOTE: A heat loss calculation should be performed to properly
determine the required furnace BTU size for the structure. Also,
the duct must be properly designed and installed for proper airflow. Existing ductwork must be inspected for proper size and to
make sure that it is properly sealed. Proper airflow is necessary
for both user comfort and equipment performance.
Before opening the furnace carton, verify that the data tags on
the carton specify the furnace model number that was ordered
from the distributor and are correct for the installation. If not,
return the unit without opening the carton. If the model number
is correct, open the carton and verify that the furnace rating
label specifies the same furnace model number that is specified on the carton label. If the model numbers do not match, return the furnace to the distributor .
IMPORTANT: Proper application, installation and maintenance of
this furnace and system is a must if consumers are to receive the full
benefits for which they have paid.
The (-)801S/(-)801P series furnaces are design certified by CSA
for use with natural and propane gases as follows:
As a Category I furnace, it may be vented vertically with type B1 vent pipe and also may be common vented as described in
these instructions.
This furnace should be installed in accordance with the American
National Standard Z223.1 - latest edition booklet entitled “National
Fuel Gas Code” (NFPA 54), and the requirements or codes of the
local utility or other authority having jurisdiction including local
plumbing or waste water codes.
With the introduction of higher efficiency furnaces, special attention
must be paid to the venting system. Only listed venting systems
may be used as stated in the installation instructions and the
Na-
tional Fuel Gas Code, ANSI Z223.1 (NFPA 54),.
Since furnace
technology and venting requirements are changing, awareness of
local, state, and federal codes and industry changes is imperative.
ST-A1220-02
FIGURE 1
FURNACE COMPONENTS
14
15
16
17
21
18
19
1
2
3
4
20
5
13
ITEM
NO.
12
11
10
9
8
DESCRIPTION
1
DOOR SWITCH
2
TRANSFORMER
3
JUNCTION BOX
4
LOW VOLTAGE TERMINAL
5
SOLID METAL BASE PAN ((-) 801P ONLY)
6
FURNACE CONTROL
7
CONTROL MOUNTING PLATE
8
CAPACITOR
9
BLOWER
10
IGNITER
11
GAS VALVE
12
INDUCED DRAFT BLOWER
13
4” FLUE ADAPTER (OPTIONAL)
14
COMBUSTION AIR INLET
15
MAIN LIMIT
16
COMBUSTION AIR DIFFUSER
17
MAIN PRESSURE SWITCH
18
BURNER
19
FLAME SENSOR
20
HEAT ASSISTED LIMIT CONTROL (HALC)
21
OVER TEMPERATURE SWITCH
7
6
ST-A1220-02-03

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Install this furnace in accordance with the American National Standard Z223.1 – latest edition entitled “National Fuel Gas Code”
(NFPA54) and requirements or codes of the local utilities or other
authorities having jurisdiction. This is available from the following:
National Fire Protection Association, Inc.
Batterymarch Park
Quincy, MA 02269
RECEIVING
Immediately upon receipt, all cartons and contents should be inspected for transit damage. Units with damaged cartons should
be opened immediately. If damage is found, it should be noted on
the delivery papers, and a damage claim filed with the last carrier.
• After unit has been delivered to job site, remove carton taking
care not to damage unit.
• Check the unit rating plate for unit size, electric heat, coil, voltage, phase, etc. to be sure equipment matches what is required for the job specification.
• Read the entire instructions before starting the installation.
• Some building codes require extra cabinet insulation and gasketing when unit is installed in attic applications.
• If installed in an unconditioned space, apply caulking around
the power wires, control wires, refrigerant tubing and condensate line where they enter the cabinet. Seal the power wires on
the inside where they exit conduit opening. Caulking is required to prevent air leakage into and condensate from forming
inside the unit, control box, and on electrical controls.
• Install the unit in such a way as to allow necessary access to
the coil/filter rack and blower/control compartment.
• Install the unit in accordance with any local code which may
apply and the national codes. Latest editions are available
from: “National Fire Protection Association, Inc., Batterymarch
Park, Quincy, MA 02269.” These publications are:
• ANSI/NFPA No. 70-(Latest Edition) National Electrical Code.
• NFPA90A Installation of Air Conditioning and Ventilating Systems.
• NFPA90B Installation of warm air heating and air conditioning
systems.
• The equipment has been evaluated in accordance with the
Code of Federal Regulations, Chapter XX, Part 3280.
CALIFORNIA RESIDENTS ONLY
IMPORTANT: All manufacturer products meet current Federal
OSHA Guidelines for safety. California Proposition 65 warnings
are required for certain products, which are not covered by the
OSHA standards.
California's Proposition 65 requires warnings for products sold in
California that contain, or produce, any of over 600 listed chemicals known to the State of California to cause cancer or birth defects such as fiberglass insulation, lead in brass, and combustion
products from natural gas.
All “new equipment” shipped for sale in California will have labels
stating that the product contains and/or produces Proposition 65
chemicals. Although we have not changed our processes, having
the same label on all our products facilitates manufacturing and
shipping. We cannot always know “when, or if” products will be
sold in the California market.
You may receive inquiries from customers about chemicals found
in, or produced by, some of our heating and air-conditioning equipment, or found in natural gas used with some of our products.
Listed below are those chemicals and substances commonly associated with similar equipment in our industry and other manufacturers.
• Glass Wool (Fiberglass) Insulation
• Carbon Monoxide (CO)
• Formaldehyde
• Benzene
More details are available at the Websites for OSHA (Occupa-
tional Safety and Health Administration), at www.osha.gov
and the
State of California's OEHHA (Office of Environmental Health Hazard Assessment), at www.oehha.org.
Consumer education is important since the chemicals and substances on the list are found
in our daily lives. Most consumers are aware that products present safety and health risks, when improperly used, handled and
maintained.
GENERAL INFORMATION (cont.)
General Information

Safety Information
SAFETY INFORMATION
!
WARNING
IN COMPLIANCE WITH RECOGNIZED CODES, IT IS RECOMMENDED THAT AN AUXILIARY DRAIN PAN BE INSTALLED UNDER THIS FURNACE AND ANY INSTALLED
EVAPORATOR COIL THAT IS LOCATED IN ANY AREA OF
A STRUCTURE WHERE DAMAGE TO THE BUILDING OR
BUILDING CONTENTS MAY OCCUR AS A RESULT OF AN
OVERFLOW OF THE A/C COIL DRAIN PAN.
!
WARNING
DO NOT INSTALL THIS FURNACE IN A MOBILE HOME!!
THIS FURNACE IS NOT APPROVED FOR INSTALLATION
IN A MOBILE HOME. DOING SO COULD CAUSE FIRE,
PROPERTY DAMAGE, PERSONAL INJURY OR DEATH.
!
WARNING
INSTALL THIS FURNACE ONLY IN A LOCATION AND POSITION AS SPECIFIED IN THE LOCATION REQUIREMENTS AND CONSIDERATIONS SECTION OF THESE
INSTRUCTIONS.
!
WARNING
IMPROPER INSTALLATION CAN RESULT IN UNSATISFACTORY OPERATION AND/OR DANGEROUS CONDITIONS
AND ARE NOT COVERED BY THE MANUFACTURER’S
WARRANTY.
!
WARNING
DO NOT BYPASS, JUMPER, OR REMOVE ANY SAFETY
SWITCH FROM THE FURNACE CONTROL CIRCUIT. IF A
SAFETY SWITCH CAUSES THE FURNACE TO SHUT
DOWN OR OPERATE INTERMITTENTLY, IT IS AN INDICATION OF A POTENTIAL SAFETY HAZARD THAT MUST BE
ADDRESSED BY A QUALIFIED TECHNICIAN, SERVICE
AGENCY OR THE GAS SUPPLIER. DO NOT RESET
SAFETY CONTROLS WITHOUT CORRECTIVE ACTION
AND/OR VERIFICATION OF PROPER SAFE OPERATION
BY A QUALIFIED INSTALLER, SERVICE AGENCY OR THE
GAS SUPPLIER.
REPLACE ANY SAFETY CONTROL COMPONENT ONLY
WITH IDENTICAL OEM REPLACEMENT PARTS. WHEN A
NEW SAFETY SWITCH IS INSTALLED, IT MUST BE
TESTED FOR A MINIMUM OF 15 MINUTES WITH THE
FURNACE OPERATING AT MAXIMUM INPUT RATE AND
WITH BOTH BLOWER AND BURNER DOOR INSTALLED.
IF THE FURNACE IS INSTALLED IN A CLOSET, THE
CLOSET DOOR MUST ALSO BE CLOSED FOR THIS
TEST. REPEAT THE TEST AT THE MINIMUM INPUT RATE
IF THE FURNACE IS A MULTI-STAGE FURNACE.
!
WARNING
USE ONLY WITH THE TYPE OF GAS APPROVED FOR
THIS FURNACE. REFER T O THE FURNACE RATING
PLATE.
!
WARNING
NEVER TEST FOR GAS LEAKS WITH AN OPEN FLAME.
USE A COMMERCIALLY AVAILABLE SOAP SOLUTION
MADE SPECIFICALLY FOR THE DETECTION OF LEAKS
TO CHECK ALL CONNECTIONS, AS SPECIFIED IN GAS
SUPPLY AND PIPING SECTION OF THESE INSTRUCTIONS.
!
WARNING
COMBUSTION PRODUCTS MUST BE DISCHARGED OUTDOORS. CONNECT THIS FURNACE TO AN APPROVED
VENT SYSTEM ONLY, AS SPECIFIED IN THE VENT PIPE
INSTALLATION SECTION OF THESE INSTRUCTIONS.
!
WARNING
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.
!
WARNING
WHENEVER THE FACTORY RETURN-AIR CONNECTION
IS NOT USED IT MUST BE SEALED. A SOLID METAL
BASE PLATE MUST BE INSTALLED AND SEALED. FACTORY BASE PLATES ARE AVAILABLE AS ACCESSORY
ITEMS. (PART NUMBERS ARE LISTED IN THE SPEC
SHEET FOR THE FURNACE.) FAILURE TO INSTALL AND
SEAL THE BASE PLATE AND RETURN AIR DUCT CONNECTIONS MAY ALLOW CARBON MONOXIDE AND
OTHER CONTAMINANTS TO BE DRAWN INTO THE CONDITIONED AIR SPACE AND DISTRIBUTED THROUGHOUT
THE HEATED SPACE.
!
WARNING
DO NOT OPERATE THE SYSTEM WITHOUT FILTERS. A
PORTION OF THE DUST ENTRAINED IN THE AIR MAY
TEMPORARILY LODGE IN THE AIR DUCT RUNS AND AT
THE SUPPLY REGISTERS. ANY CIRCULATED DUST PARTICLES WILL BE HEATED AND CHARRED BY CONTACT
WITH THE FURNACE HEAT EXCHANGER. THIS SOOTY
RESIDUE WILL SOIL CEILINGS, WALLS, DRAPES, CARPETS AND OTHER HOUSEHOLD ARTICLES. SOOT DAMAGE MAY ALSO RESULT WITH, OR WITHOUT, FILTERS IN
PLACE, WHEN CERTAIN TYPES OF CANDLES ARE
BURNED, OR CANDLEWICKS ARE LEFT UNTRIMMED.
6
!
WARNING
COMBUSTION AND VENTILATION AIR MUST BE PROVIDED TO THE FURNACE AS REQUIRED BY THE NATIONAL FUEL-GAS CODE (U.S.) AND CSA B149.1
(CANADA) AND THE COMBUSTION AND VENTILATION
AIR SECTION OF THESE INSTRUCTIONS.

7
SAFETY
Safety Information
IMPORTANT INFORMATION ABOUT
EFFICIENCY AND INDOOR AIR
QUALITY
Central cooling and heating equipment is only as efficient as the
duct system that carries the cooled or heated air. To maintain efficiency, comfort and good indoor air quality, it is important to have
the proper balance between the air being supplied to each room
and the air returning to the cooling and heating equipment.
Proper balance and sealing of the duct system improves the efficiency of the heating and air conditioning system and improves
the indoor air quality of the home by reducing the amount of airborne pollutants that enter homes from spaces where the ductwork and / or equipment is located. The manufacturer and the
U.S. Environmental Protection Agency’s Energy Star Program
recommend that central duct systems be checked by a qualified
contractor for proper balance and sealing.
FIGURE 2
MIGRATION OF DANGEROUS SUBSTANCES, FUMES, AND ODORS INTO
LIVING SPACES
Adapted from
Residential Duct Diagnostics and Repair
, with permission of Air Conditioning
Contractors of America (ACCA).
!
WARNING
DUCT LEAKS CAN CREATE AN UNBALANCED SYSTEM
AND DRAW POLLUTANTS SUCH AS DIRT, DUST, FUMES
AND ODORS INTO THE HOME CAUSING PROPERTY
DAMAGE. FUMES AND ODORS FROM TOXIC, VOLATILE
OR FLAMMABLE CHEMICALS, AS WELL AS AUTOMOBILE EXHAUST AND CARBON MONOXIDE (CO), CAN BE
DRAWN INTO THE LIVING SPACE THROUGH LEAKING
DUCTS AND UNBALANCED DUCT SYSTEMS CAUSING
PERSONAL INJURY OR DEATH (SEE FIGURE 2).
• IF AIR-MOVING EQUIPMENT OR DUCTWORK IS LOCATED IN GARAGES OR OFF-GARAGE STORAGE
AREAS - ALL JOINTS, SEAMS, AND OPENINGS IN THE
EQUIPMENT AND DUCT MUST BE SEALED TO LIMIT
THE MIGRATION OF TOXIC FUMES AND ODORS INCLUDING CARBON MONOXIDE FROM MIGRATING
INTO THE LIVING SPACE.
• IF AIR-MOVING EQUIPMENT OR DUCTWORK IS LOCATED IN SPACES CONTAINING FUEL BURNING APPLIANCES SUCH AS WATER HEATERS OR BOILERS ALL JOINTS, SEAMS, AND OPENINGS IN THE EQUIPMENT AND DUCT MUST ALSO BE SEALED TO PREVENT DEPRESSURIZATION OF THE SPACE AND
POSSIBLE MIGRATION OF COMBUSTION BYPRODUCTS INCLUDING CARBON MONOXIDE INTO THE LIVING SPACE.
!
WARNING
BLOWER AND BURNERS MUST NEVER BE OPERATED
WITHOUT THE BLOWER DOOR IN PLACE. THIS IS TO
PREVENT DRAWING GAS FUMES (WHICH COULD CONTAIN HAZARDOUS CARBON MONOXIDE) INTO THE
HOME THAT COULD RESULT IN PERSONAL INJURY OR
DEATH.
!
WARNING
ALWAYS INSTALL THE FURNACE TO OPERATE WITHIN
THE FURNACE’S INTENDED TEMPERATURE-RISE
RANGE WITH A DUCT SYSTEM WHICH HAS AN EXTERNAL STATIC PRESSURE WITHIN THE ALLOWABLE
RANGE, AS SPECIFIED IN THE DUCTING SECTION OF
THESE INSTRUCTIONS. SEE ALSO FURNACE RATING
PLATE.
THE FURNACE MAY BE USED FOR HEATING OF BUILDINGS OR STRUCTURES UNDER CONSTRUCTION.
INSTALLATION MUST COMPLY WITH ALL INSTALLATION
INSTRUCTIONS INCLUDING:
PROPER VENT INSTALLA TION;
FURNACE OPERATING UNDER THERMOSTAT
CONTROL;
RETURN AIR DUCT SEALED TO THE FURNACE;
AIR FILTERS IN PLACE;
SET FURNACE INPUT RATE AND TEMPERATURE
RISE PER RATING PLATE MARKINGS;
MEANS FOR PROVIDING OUTDOOR AIR RE-
QUIRED FOR COMBUSTION;
RETURN AIR TEMPERATURE MAINTAINED BE-
TWEEN 55°F (13°C) AND 80°F (27°C); AND
CLEAN FURNACE, DUCT WORK AND COMPO-
NENTS UPON SUBSTANTIAL COMPLETION OF
THE CONSTRUCTION PROCESS, AND VERIFY
THAT THE FURNACE OPERATING CONDITIONS
INCLUDING IGNITION, INPUT RATE, TEMPERATURE RISE AND VENTING, ACCORDING TO THE
INSTRUCTIONS AND CODES.

8
1. IMPORTANT: If using a cooling evaporator coil with this fur-
nace, be sure the air passes over the heat exchanger before
passing over the cooling coil. The cooled air passing over the
warm ambient air inside the heat exchanger tubes can cause
condensation inside the tubes resulting in corrosion and eventual failure. An auxiliary drain pan should extend under any
evaporator coil installed with the furnace.
If there are manual dampers, they must be equipped to prevent
heating or cooling operation unless the damper is in the full heat
or cool position.
2. NOTE: This furnace is shipped with heat exchanger support
brackets installed under the back of the heat exchanger. These
may be removed before installation, but it is not required.
3. IMPORTANT:
This furnace is not approved or recommended
for installation on its back, with access doors facing upwards.
4. This furnace is suitable for installation in buildings constructed
on-site. This heating unit should be centralized with respect to
the heat distribution system as much as practicable.
5. NOTE: These furnaces are approved for installation in attics,
as well as alcoves, utility rooms, closets and crawlspaces.
6. IMPORTANT:
Support this unit when installed. For attic or cra wl
space installation, horizontal furnaces may be installed on combustible wood flooring or by using support brackets. See Figure
3.
7. IMPORTANT:
If installing in a utility room, be sure the door is
wide enough to:
a. allow the largest part of the furnace to pass; or
b. allow any other appliance (such as a water heater) to pass.
SITE SELECTION
1. Select a site in the building near the center of the proposed, or existing, duct system.
2. Give consideration to the vent system piping when selecting the furnace location. Be sure the venting system
can get from the furnace to the termination with minimal
length and elbows.
3. Locate the furnace near the existing gas piping. Or, if
running a new gas line, locate the furnace to minimize
the length and elbows in the gas piping. See Figure 3.
4. Locate the furnace to maintain proper clearance to
combustibles as shown in following Figure 4.
CLEARANCE – ACCESSIBILITY
The design of forced air furnaces with input ratings as
listed in the tables under Figure 4 are to combustible materials shown in inches.
See name/rating plate and clearance label for specific
model number and clearance information.
Service clearance of at least 24 inches (30 cm) is recommended in front of all furnaces.
NOTE: Use recommended 24” (30 cm) clearance if accessibility clearances are greater than fire protection clearances.
ACCESSIBILITY CLEARANCES, WHERE GREATER, MUST
TAKE PRECEDENCE OVER FIRE PROTECTION CLEARANCES.
GENERAL INFORMATION
LOCATION REQUIREMENTS
Location
!
WARNING
WHEN THIS FURNACE IS INSTALLED IN A RESIDENTIAL
GARAGE, IT MUST BE INSTALLED SO THE BURNERS
AND IGNITION SOURCE ARE LOCATED NO LESS THAN
18 INCHES [450MM] ABOVE THE FLOOR. THIS IS TO PREVENT THE RISK OF IGNITING FLAMMABLE VAPORS
WHICH MAY BE PRESENT IN A GARAGE. ALSO, THE FURNACE MUST BE LOCATED OR PROTECTED TO AVOID
PHYSICAL DAMAGE BY VEHICLES. FAILURE TO FOLLOW
THESE WARNINGS CAN CAUSE A FIRE OR EXPLOSION,
RESULTING IN PROPERTY DAMAGE, PERSONAL INJURY
OR DEATH.
!
WARNING
THIS FURNACE IS NO T APPROVED OR RECOMMENDED
FOR INSTALLATION ON ITS BACK, WITH ACCESS DOORS
F ACING UPWARDS.
!
WARNING
DO NOT LIFT THE UNIT BY THE HEAT EXCHANGER
TUBES. DOING SO CAN D AMAGE THE HEAT EXCHANGER ASSEMBLY.

11
Proper air flow is required for the correct operation of this
furnace. Restricted air flow can cause erratic operation and
can damage the heat exchanger. The duct system must
carry the correct amount of air for heating and cooling if
summer air conditioning is used.
IMPORTANT: When using outside air, design and adjust
the system to maintain a return air temperature ABOVE
55° F during the heating season.
NOTE: Return air grilles and warm air registers must not
be obstructed or closed.
UPFLO W INSTALLATIONS
1. Position the unit to minimize long runs of duct or runs
of duct with many turns and elbows.
2. For side return: Cut an opening in the side. The opening should be cut the full width and height of the
knockouts on the unit. See Figure 6.
3. If summer air conditioning is desired, position the indoor coil on the supply-air side of the unit. Ensure that
no air can bypass the coil.
4. Connect the furnace to the supply air plenum. See Figure 7.
5. Connect the return air ducting to the return-air opening
at the bottom and/or side of the unit. Make the connections air-tight to prevent the migration of toxic fumes
and odors including carbon monoxide from migrating
into the living space.
6. If a filter is installed near the furnace, be sure to have
adequate space for installation and removal of the unit
filter.
7. NOTE: Where the maximum airflow is 1800 CFM or
more, BOTH sides or the bottom must be used for the
return air. Do not take return air from the back of the
unit.
NOTE: DO NOT take return air from furnace rooms,
garages or cold areas. Avoid return air from utility rooms,
kitchens, laundry rooms and bathrooms.
DUCTING
Ducting
!
WARNING
BLOWER AND BURNERS MUST NEVER BE OPERATED
WITHOUT THE BLOWER DOOR IN PLACE. THIS IS TO
PREVENT DRAWING GAS FUMES (WHICH COULD CONTAIN HAZARDOUS CARBON MONOXIDE) INTO THE
HOME THAT COULD RESULT IN PERSONAL INJURY OR
DEATH.
!
WARNING
THE SOLID METAL BASE (SHIPPED WITH THE 801P
FURNACE) PLATE MUST BE INSTALLED IN THE
FURNACE BOTTOM WHEN USING SIDE AIR RETURN. FAILURE TO INSTALL A BASE PLATE COULD
CAUSE THE PRODUCTS OF COMBUSTION TO CIRCULATE INTO THE LIVING SP ACE AND CREATE
POTENTIAL LY HAZARDOUS CONDITIONS, INCLUDING CARBON MONOXIDE POISONING OR DEATH.
FOR BOTTOM RETURN, A SOLID METAL BASE PAN
MUST NOT BE INSTALLED. SEE FIGURE 5.
!
WARNING
SOME HEATING AIRFLOW VALUES MAY BE
HIGHER THAN THOSE REQUIRED FOR COOLING.
BE SURE TO SIZE DUCT FOR THE MAXIMUM POSSIBLE AIRFLOW VALUE.
SIZE AIRFLOW DISTRIBUTION SYSTEM TO ACCEPTABLE INDUSTRY STANDARDS AND METHODS. TOTAL STATIC PRESSURE DROP OF THE AIR
DISTRIBUTION SYSTEM SHOULD NOT EXCEED .8
INCHES W.C. THIS WILL INCLUDE ANY AIR CONDITIONER COIL, AIR FILTRATION SYSTEM, ZONING
SYSTEM, DUCTWORK, ETC. REFER TO ADDED
EQUIPMENT TECHNICAL INFORMATION TO OBTAIN
PRESSURE DROP INFORMATION WHEN EQUIPMENT IS OPERATING AT RECOMMENDED HEATING OR COOLING CFMS.

14
Combustion Air
COMBUSTION AND VENTILATION AIR
1. IMPORTANT:
Air for combustion and ventilation must not
come from a corrosive atmosphere. Any failure due to corrosive elements in the atmosphere is excluded from warranty
coverage.
2. Combustion air must be free of acid forming chemicals; such
as sulphur, fluorine and chlorine. These elements are found in
aerosol sprays, detergents, bleaches, cleaning solvents, air
fresheners, paint and varnish removers, refrigerants and many
other commercial and household products. Vapors from these
products when burned in a gas flame form acid compounds.
The acid compounds increase the dew point temperature of
the flue products and are highly corrosive after they condense.
3. The following types of installation may require OUTDOOR AIR
for combustion, due to chemical exposures:
• Commercial buildings
• Buildings with indoor pools
• Furnaces installed in laundry rooms
• Furnaces in hobby or craft rooms
• Furnaces installed near chemical storage areas.
4. If combustion air is exposed to the following substances (but
not limited to the following), it should not be used and the furnace may require outdoor air for combustion.
• 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 curing and acid washing materials
Combustion air requirements are determined by whether the furnace is in an open (unconfined) area or in a confined space such
as a closet or small room.
When the furnace is installed in the same space with other gas appliances, such as a water heater, be sure there is an adequate
supply of combustion and ventilation air for the furnace and the
other appliances. Do not delete or reduce the combustion air supply required by the other gas appliances in this space. See Z223.1,
National Fuel Gas Code (NFPA 54). An unconfined space must
have at least 50 cubic feet (volume) for each 1,000 BTUH of the
total input of all appliances in the space. If the open space containing the appliances is in a building with tight construction (contemporary construction), outside air may still be required for the
appliances to burn and vent properly. Outside air openings should
be sized the same as for a confined space.
IMPORTANT: ONLY THE CURRENT VENT INSTRUCTIONS
APPLY. All gas furnaces cannot be common-vented.
OVERTEMPERATURE SAFETY
SWITCHES
Furnaces are equipped with safety switches in the burner compartment to protect against over-temperature conditions caused
by inadequate combustion air supply. The switches are located
in the burner compartment. If a switch is tripped it must be manually reset after clearing the fault condition which caused it to
open.
IMPORTANT:
This is not a direct vent furnace. Review venting
instructions before installing.
!
WARNING
THIS FURNACE AND ANY OTHER FUEL-BURNING APPLIANCE MUST BE PROVIDED WITH ENOUGH FRESH AIR
FOR PROPER COMBUSTION AND VENTILATION OF THE
FLUE GASES. MOST HOMES WILL REQUIRE THAT OUTSIDE AIR BE SUPPLIED INTO THE FURNACE AREA. FAILURE TO DO SO CAN CAUSE DEATH FROM CARBON
MONOXIDE POISONING.
!
WARNING
ADEQUATE FACILITIES FOR PROVIDING AIR FOR COMBUSTION AND VENTILATION MUST BE PROVIDED IN ACCORDANCE WITH SECTION 5.3, AIR FOR COMBUSTION
AND VENTILATION, OF THE NATIONAL FUEL GAS CODE,
ANSI, Z223.1 LATEST EDITION OR APPLICABLE PROVISIONS FOR THE LOCAL BUILDING CODES, AND NOT
OBSTRUCTED SO AS TO PREVENT THE FLOW OF AIR TO
THE FURNACE.
COMBUSTION AIR REQUIREMENTS
!
WARNING
ALL FURNACE INSTALLATIONS MUST COMPLY WITH
THE NATIONAL FUEL GAS CODE AND LOCAL CODES TO
PROVIDE ADEQUATE COMBUSTION AND VENTILATION
AIR FOR THE FURNACE. FAILURE TO DO SO CAN CREATE HAZARDOUS CONDITIONS RESULTING IN PROPERTY DAMAGE, BODILY INJURY OR DEATH FROM
SMOKE, FIRE OR CARBON MONOXIDE.
!
WARNING
DO NOT BYPASS, JUMPER, OR REMOVE ANY SAFETY
SWITCH FROM THE FURNACE CONTROL CIRCUIT. IF A
SAFETY SWITCH CAUSES THE FURNACE TO SHUT
DOWN OR OPERATE INTERMITTENTLY, IT IS AN INDICATION OF A POTENTIAL SAFETY HAZARD THAT MUST BE
ADDRESSED BY A QUALIFIED TECHNICIAN, SERVICE
AGENCY OR THE GAS SUPPLIER. DO NOT RESET
SAFETY CONTROLS WITHOUT CORRECTIVE ACTION
AND/OR VERIFICATION OF PROPER SAFE OPERATION
BY A QUALIFIED INSTALLER, SERVICE AGENCY OR THE
GAS SUPPLIER.
REPLACE ANY SAFETY CONTROL COMPONENT WITH
IDENTICAL OEM REPLACEMENT PARTS ONLY.

15
COMBUSTION AND VENTILATION AIR (cont.)
For improved indoor air quality, added safety and product performance we recommend direct vent type installations. If non-direct type vent system is used, the requirements for combustion
air must be provided as identified in the National Fuel Gas Code.
Combustion air requirements are determined by whether the furnace is in an open (unconfined) area or in a confined space such
as a closet or small room.
FURNACE LOCATED IN AN UNCONFINED SPACE
USING INDOOR AIR FOR COMBUSTION:
An unconfined space must have at least 50 cubic feet for each
1,000 BTUH of total input for all appliances in the space. Table 1
below specifies minimum space requirements and a few examples of the room sizes required for different inputs. The sizes are
based on 8-foot ceilings.
If the open space containing the furnace is in a building with tight
construction, outside air may still be required for the furnace to
operate and vent properly. Outside air openings should be sized
the same as for a confined space.
FURNACE LOCATED IN A CONFINED
SPACE
A confined space is defined as any space for a given furnace input
rating which is smaller than that which is specified in Table 1 as
minimum for an “unconfined” space. If the space is less than that
specified in this table, the space is defined as
“confined”.
If the space is small enough to be designated as “confined”, it
must have openings into the space which are located in accordance with the requirements set forth in the following subsections
A and B. Size connected to the heated area or to the outside, and
by the input of ALL appliances in the space.
If the confined space is within a building with tight construction,
combustion air must be taken from outdoors or from an area
freely communicating with the outdoors.
A. USING INDOOR AIR FOR COMBUSTION:
IMPORTANT: Air should not be taken from a heated space
with a fireplace, exhaust fan or other device that may produce negative pressure.
If combustion air is taken from the heated area, the openings
must each have at least 100 square inches of free area.
Each opening must have at least one square inch of free
area for each 1,000 BTUH of total input in the space. Table 2
shows some typical examples of openings required for combustion air openings required for a confined space.
B. USING OUTDOOR AIR FOR COMBUSTION:
IMPORTANT: Do not take air from an attic space that is
equipped with power ventilation.
The confined space must communicate with the outdoors in
accordance with Methods 1 or 2 below. The minimum dimension of air openings shall not be less than 3 inches. Where
ducts are used, they shall be of the same cross-sectional
area as the free area of the openings to which they connect.
METHOD 1:
Two permanent openings, one located within 12 inches of the
top and one located within 12 inches of the bottom of the enclosure, shall be provided. The openings shall communicate
directly, or by ducts, with the outdoors or spaces (crawl or
attic) that freely communicate with the outdoors.
Combustion Air
COMBUSTION AIR REQUIREMENTS: CONFINED AND
UNCONFINED SPACES
!
WARNING
ALL FURNACE INSTALLATIONS MUST COMPLY WITH
THE NATIONAL FUEL GAS CODE, NFPA 54 AND LOCAL
CODES TO PROVIDE ADEQUATE COMBUSTION AND
VENTILATION AIR FOR THE FURNACE. FAILURE TO DO
SO CAN RESULT IN EXPLOSION, FIRE, PROPERTY DAMAGE, CARBON MONOXIDE POISONING, PERSONAL INJURY OR DEATH.
!
WARNING
READ AND FOLLOW THE GENERAL VENTING REQUIREMENTS AND GUIDELINES OF THIS MANUAL FOR ADDI-
TIONAL VENTING REQUIREMENTS PERTAINING TO ALL
FURNACE INSTALLATIONS (INCLUDING DIRECT AND
NON-DIRECT VENTING). FAILURE TO FOLLOW ALL INSTRUCTIONS IN THIS MANUAL CAN RESULT IN EQUIPMENT FAILURE, EQUIPMENT DAMAGE, PROPERTY
DAMAGE, PERSONAL INJURY OR DEATH.
150,000 7,500 940 32 x 30
TABLE 1: MINIMUM SPACE REQUIREMENTS
FOR UNCONFINED SPACE, NON-DIRECT VENT
TABLE 2: MINIMUM FREE AREA
OPENING REQUIRED FOR A
FURNACE LOCATED IN A
CONFINED SPACE USING
INDOOR AIR FOR COMBUSTION.
TABLE 7: MINIMUM SPACE REQUIREMENTS
FOR UNCONFINED SPACE, NON-DIRECT VENT*
Input
(BTUH)
50,000 2,500 313 16 x 20
75,000 3,750 470 24 x 20
100,000 5,000 625 32 x 20
125,000 6,300 790 36 x 30
Minimum
Space
(Cubic Ft)
Minimum Area
with 8
Ceilings (sq )
Typical Room
Size w/ 8'
Ceilings ( x )
TABLE 8: MINIMUM FREE AREA
OPENING REQUIRED FOR A
FURNACE LOCATED IN A
CONFINED SPACE USING
INDOOR AIR FOR COMBUSTION.
Input (BTUH)
50,000 100
75,000 100
100,000 100
125,000 130
Free Area for Each
Opening (sq inches)

A. Where directly communicating with the outdoors through an
opening or where communicating to the outdoors through
vertical ducts as shown in Figure 11, each opening shall
have a minimum free area of 1 square inch for each 4,000
BTUH of total appliance input rating of all equipment in the
enclosure. Table 3 specifies the minimum area for
each of the 2 combustion air openings and minimum round
duct diameter for direct openings and vertical ducting only.
B. Where communicating with the outdoors through horizontal ducts, each opening shall have a minimum free area of 1
square inch for each 2,000 BTUH of total appliance input rating of all equipment in the enclosure (see Figure 12). Table 4
specifies the minimum area for each of the 2 combustion air
openings and minimum round duct diameter for horizontal
ducting only.
METHOD 2:
One permanent opening located within 12 inches of the top of
the enclosure, shall be permitted where the equipment has
clearances of at least 1 inch from the sides and back and 6
inches from the front of the appliance. The opening shall directly communicate with the outdoors or communicate
through a vertical or horizontal duct to the outdoors or spaces
(crawl or attic) that freely communicate with the outdoors,
and shall have a minimum of:
TABLE 3: MINIMUM FREE AREA REQUIRED
FOR EACH OPENING (WHEN TWO OPENINGS
ARE USED) WITH A FURNACE:
1. LOCATED IN A CONFINED SPACE
2. USING OUTDOOR AIR FOR COMBUSTION
3. COMMUNICATING DIRECTLY TO THE
3. OUTSIDE THROUGH AN OPENING OR
3. THROUGH A VERTICAL DUCT.
16
Combustion Air
COMBUSTION AND VENTILATION AIR (cont.)
TABLE 4: MINIMUM FREE AREA REQUIRED
FOR EACH OPENING (WHEN TWO OPENINGS
ARE USED) WITH A FURNACE:
1. LOCATED IN A CONFINED SPACE
2. USING OUTDOOR AIR FOR COMBUSTION
3. COMMUNICATING DIRECTLY TO THE
3. OUTSIDE THROUGH A HORIZONTAL DUCT.
TABLE 5: MINIMUM FREE AREA REQUIRED
FOR EACH OPENING (WHEN TWO OPENINGS
ARE USED) WITH A FURNACE:
1. LOCATED IN A CONFINED SPACE
2. USING OUTDOOR AIR FOR COMBUSTION
3. COMMUNICATING DIRECTLY TO THE
3. OUTSIDE THROUGH A HORIZONTAL DUCT.
COMBUSTION AIR REQUIREMENTS: CONFINED AND
UNCONFINED SPACES
GAS
WATER
HEATER
FURNACE
12”
MAX
12”
MAX
NOTE:
EACH OPENING SHALL
HAVE A FREE AREA OF
NOT LESS THAN ONE
SQUARE INCH PER
1,000 BTU PER HOUR OF
THE TOTAL INPUT
RATING OF ALL
EQUIPMENT IN THE
ENCLOSURE, BUT NOT
LESS THAN 100
SQUARE INCHES.
ST-A1227-01
FIGURE 10
NON-DIRECT VENT
AIR FROM
HEATED
SPACE
VENT PENETRATIONS
FOR NON DIRECT VENT FURNACES
AIR FROM HEATED SPACE
TABLE 9 : MINIMUM FREE AREA REQUIRED
FOR EACH OPENING (WHEN TWO OPENINGS
ARE USED) WITH A FURNACE:
1. LOCATED IN A CONFINED SPACE
2. USING OUTDOOR AIR FOR COMBUSTION
3. COMMUNICATING DIRECTLY TO THE
OUTSIDE THROUGH AN OPENING OR
T H R O U G H A V E R T I C A L V E N T D U C T . *
Total Input for
ALL Gas
Appliances
(BTUH)
50,000 13 5
75,000 19 5
100,000 25 6
125,000 32 8
TABLE 1 0: MINIMUM FREE AREA REQUIRED
FOR EACH OPENING (WHEN TWO OPENINGS
ARE USED) WITH A FURNACE:
1. LOCATED IN A CONFINED SPACE
2. USING OUTDOOR AIR FOR COMBUSTION
3. COMMUNICATING DIRECTLY TO THE
OUTSIDE THROUGH A H ORIZONTAL DUCT.
Total Input for
ALL Gas
Appliances
(BTUH)
50,000 25 6
75,000 38 8
100,000 50 8
125,000 63 10
Free Area for
Each Opening
w h e n 2 S e p a r a t e
Openings are
used (sq inches)
Free Area for
Each Opening
when 2 Separate
Openings are
used (sq inches)
R o u n d P i p e D u c t
Diameter ( Vercal
Duct Only) (inches)
Round Pipe Duct
Diameter
(Horizontal Duct
Only) (inches)
TABLE 1 1: MINIMUM FREE AREA REQUIRED
FOR AN OPENING (WHEN O N E OPENING IS
USED) WITH A FURNACE:
1. LOCATED IN A CONFINED SPACE
2. USING OUTDOOR AIR FOR COMBUSTION
3. COMMUNICATING DIRECTLY TO THE
OUTSIDE.
Total Input for
ALL Gas
Appliances
(BTUH)
50,000 25 6
75,000 38 8
100,000 50 8
125,000 63 10
*
Free Area for an
Opening when 1
Opening is used
(sq inches)
Round Pipe Duct
Diameter (inches)

17
COMBUSTION AND VENTILATION AIR (cont.)
A. 1 Square inch for each 3,000 BTUH of the total input rat-
ing of all equipment located in the enclosure
and
B. Not less than the sum of the areas of all vent connectors
in the confined space.
If the unit is installed where there is an exhaust fan, sufficient
ventilation must be provided to prevent the exhaust fan from creating negative pressure.
AIR INTAKE PIPE CONNECTION
A double-elbow may be installed to top inlet air opening,
BUT IS NOT REQUIRED.This will help to prevent accidental
blockage of the intake opening. Reference Figure 13 for
proper elbow diameter.
NOTE: Inlet is specifically designed to prevent material from
being pulled into furnace. If elbows are not used, the intake opening must be kept clean and free of debris.
ATTACH OPTIONAL DOUBLE ELBOW TO TOP INLET AIR
OPENING TO PREVENT ACCIDENTAL BLOCKAGE OF
INTAKE OPENING. THIS IS NOT A REQUIREMENT. (SEE
PREVIOUS PAGE.) SINGLE ELBOW IS ALLOWED BUT
MAY NOT PREVENT DEBRIS FROM BEING DROPPED
INTO THE FURNACE.
GROUND OR
SHELF SURFACE
6" MIN.
6" MININUM
CLEARANCE
PVC
DOUBLE
ELBOW
#8 SCREWS
METAL FLUE
PIPE ONLY
EXHAUST
#8 SCREWS
FIGURE 13
COMBUSTION AIR FITTING – NON-ATTIC COMBUSTION AIR PULL
Combustion Air
GAS
WATER
HEATER
FURNACE
OPTIONAL 1 SQ. INCH PER 4000 BTUH INLET AIR
GABLE
VENT
VENTILATED
ATTIC GABLE OR
SOFFIT VENTS
OUTLET AIR
IN ATTIC
MUST BE
ABOVE
INSULATION
1 SQ. INCH PER
4000 BTUH INLET AIR
12” MAX
1 SQ. INCH PER
4000 BTUH
OUTLET AIR
GAS
WATER
HEATER
FURNACE
12”
MAX
INLET AIR 1 SQ. INCH
PER 2000 BTUH
OUTLET AIR 1 SQ. INCH
PER 2000 BTUH
OUTLET AIR
1 SQ. INCH PER
4000 BTUH
INLET AIR
1 SQ. INCH PER
4000 BTUH
ST-A1227-03
ST-A1227-02
FIGURE 11
NON-DIRECT VENT
AIR FROM ATTIC
OR CRAWL
SPACE
FIGURE 12
NON-DIRECT VENT
OUTSIDE AIR
USING A
HORIZONTAL
DUCT
COMBUSTION AIR REQUIREMENTS: CONFINED AND
UNCONFINED SPACES
VENT PENETRATIONS
FOR NON DIRECT VENT FURNACES
AIR FROM ATTIC/CRAWL SPACE
VENT PENETRATIONS
FOR NON DIRECT VENT FURNACES
AIR FROM ATTIC/CRAWL SPACE

19
COMBUSTION AND VENTILATION AIR (cont.)
GENERAL INFORMATION
The furnace must be vented in accordance with these instructions,
National Fuel Gas Code, ANSI Z223.1 and requirements or codes
of the local utility or other authority having jurisdiction.
DRAFT INDUCER
FURNACE CATEGORY INFORMATION
This furnace is shipped as a Category I type induced draft furnace. A Category I furnace operates with a nonpositive vent pressure and has a vent gas temperature at least 140°F above the
dew point of the vent gases. A Category I type may be a draft
hood equipped furnace or have a fan assisted combustion system (induced draft). The inducer is used to pull flue products
through the combustion chamber and as they leave the furnace,
most of the energy has been dissipated. The buoyant effect of the
flue gases provides venting to the outdoors.
During the off cycle, the inducer is off and there is very little flow
through the vent, cooling the vent. During the on cycle there is no
dilution airflow, as with a draft hood type furnace. Although the
vent heats up rapidly without dilution air, the flue products contain
more water vapor, which results in a higher dew point temperature. It is most important that you follow the guidelines in these
instructions to prevent the possible formation of condensation in
the venting system.
As a Category I furnace it may be vented vertically with type B-1
vent pipe and also may be common vented, as described in
these instructions.
IMPORTANT APPLICATION NOTES
When the furnace is used as a replacement, the existing vent
system should be inspected to assure that there are no obstructions, blockage, or any signs of corrosion and is properly sized for
use with this furnace.
NOTE: When the vent table permits more than one diameter of
pipe for a connector or vent, the smallest permitted diameter
must be used.
Vent pipe may be type “B-1,” either rigid or suitable flexible construction that carries a U.L. listing.
Common venting is allowed with vertical B-1 vent systems, and
lined masonry chimneys. Follow the National Fuel Gas Code
ANSI Z223.1 or proper installation practices.
NOTE: Follow combustion air instructions as outlined in this manual.
Single wall vent connectors to “B-1 vent or masonry chimneys”
may be used under the guidelines of the National Fuel Gas Code
ANSI Z223.1.
The entire length of the vent connector shall be readily accessible for inspection, cleaning and replacement.
“B-1” VERTICAL VENTING
NOTE: Refer to the National Fuel Gas Code, ANSI Z223.1.
Type “B-1” vents must be installed in accordance with the terms
of their listings and the vent manufacturer’s instructions.
“B-1” vents must be supported and spaced in accordance with
their listings and the manufacturer’s instructions. All vents must
be supported to maintain their minimum clearances from combustible material.
*NOTE: All furnaces have a 3” vent connection as shipped from the factory. A 3” to 4”, 3” to 5”, or 4” to 5” vent transition may be required when
vertically vented or common vented with metal vent pipes. THE VENT
TRANSITION CONNECTION MUST BE MADE AT THE FURNACE
VENT EXIT. It must originate with an adapter if required, at the furnace
flue collar and terminate either in a listed cap or roof assembly. When
common venting, the vent connector size may differ from the above diameters depending on application. See National Fuel Gas Code ANSI
Z223.1 or latest edition tables.
!
WARNING
DEVICES ATTA CHED TO THE FLUE OR VENT FOR THE
PURPOSE OF REDUCING HEAT LOSS UP THE CHIMNEY
HAVE NOT BEEN TESTED AND HAVE NOT BEEN INCLUDED IN THE DESIGN CERTIFICATION OF THIS FURNACE. WE, THE MANUFACTURER, CANNOT AND WILL
NOT BE RESPONSIBLE FOR INJURY OR DAMAGE
CAUSED BY THE USE OF SUCH UNTESTED AND/OR UNCERTIFIED DEVICES, ACCESSORIES OR COMPONENTS.
!
WARNING
VENT PIPE ATTACHING HOLES MUST BE PREDRILLED
IN THE DRAFT INDUCER COLLAR TO PREVENT DAMAGING THE INDUCER. DRILL 1/8” DIAMETER HOLES
THROUGH THE VENT PIPE AND COLLAR AND USE #8
SCREWS TO ATTACH. SEE FIGURE 16. FAILURE TO FOLLOW THIS WARNING CAN CAUSE RECIRCULATION OF
FLUE PRODUCTS CAUSING CARBON MONOXIDE POISONING RESULTING IN PERSONAL INJURY OR DEATH.
VENTING
VERTICAL VENTING
Categorized
Furnace Vent
Input Size Recommended
(See NFGC)
50K 3”
75K *4”
100K *4”
125K *5”
150K *5”
Combustion Air

20
Combustion Air
COMBUSTION AND VENTILATION AIR (cont.)
VERTICAL VENT SYSTEMS:
1. A gas vent shall terminate above the roof surface with a listed
cap or listed roof assembly. Gas vents 12 inches in size or
smaller with listed caps shall be permitted to be terminated in
accordance with Figure 15, provided they are at least 8 feet
from a vertical wall or similar obstruction. All other gas vents
shall terminate not less than 2 feet above the highest point
where they pass through the roof and at least 2 feet higher
than any portion of a building within 10 feet.
2. A type B-1 gas vent shall terminate at least 5 feet in vertical
height above the highest connected equipment draft hood or
flue collar.
3. Must rise
1
/4” per foot away from the furnace on horizontal runs
and be supported with straps or hangers so it has no sags or
dips. Supports at 4 foot intervals and at all elbows are recommended.
4. The vent connector must be mechanically fastened to the outlet collar of the furnace with at least (2) sheet metal screws except vent connectors that are B-1 material. These shall be
assembled in accordance with the manufacturer’s instructions.
See Figures 16 and 17.
5. Any angle greater than 45 degrees from the vertical is considered horizontal. The total horizontal distance of a vent plus the
horizontal vent connector serving draft-hood equipped appliances shall not be greater than 75 percent of the vertical
height of the vent.
Single appliance venting of a fan assisted furnace into a tile-lined
masonry chimney is prohibited. The chimney must be lined with
either Type B vent or with a listed, single wall, metal lining system. Reference National Fuel Gas Code, ANSI Z223.1. See Figure 18 for typical B-1 vent chase.
NOTE:A chimney adapter is available as an accessory (see accessory section of this manual). Follow manufacturer’s instructions.
SPECIAL VENT SYSTEMS (SVS)
IMPORTANT:
It is THE FURNACE MANUFACTURER’s position
now that new
installations of any HTPV pipe used in a category
III
vent application, including Selkirk’s Selvent™ IIHTPV prod-
uct, should cease immediately.
!
WARNING
DO NOT CONNECT THIS FURNACE TO A CHIMNEY USED
TO VENT A SOLID FUEL APPLIANCE (WOOD OR COAL).
VENTING WITH A SOLID FUEL APPLIANCE CAN LEAD TO
IMPROPER FUNCTIONING OF THE UNIT, AND DUE TO
SOOTING, THE POSSIBILITY OF FIRE RESULTING IN
PROPERTY DAMAGE, PERSONAL INJURY OR DEATH.
A0991-01
FIGURE 16
ATTACHING TO DRAFT INDUCER COLLAR
FIGURE 15
TYPICAL VENTING WITH “B-1” VENT
ST-A1220-24
LISTED CAP
LISTED GAS VENT
MINIMUM ALLOWABLE HEIGHT
FROM ROOF TO DISCHARGE OPENING
X
12
ROOF PITCH = X/12
ROOF PITCH “H” (MIN.) FT.
FLAT TO 6/12 1.0
OVER 6/12 TO 7/12 1.25
OVER 7/12 TO 8/12 1.5
OVER 8/12 TO 9/12 2.0
OVER 9/12 TO 10/12 2.5
OVER 10/12 TO 11/12 3.25
OVER 11/12 TO 12/12 4.0
OVER 12/12 TO 14/12 5.0
OVER 14/12 TO 16/12 6.0
OVER 16/12 TO 18/12 7.0
ST-A1220-24
OVER 18/12 TO 20/12 7.5
OVER 20/12 TO 21/12 8.0

22
COMBUSTION AND VENTILATION AIR (cont.)
PO WER VENT SYSTEMS
When vertical venting is not possible, the only acceptable method
for horizontal venting is with the use of Tjernlund model GPAK1TR or Field Controls models SWG-4R power venter. Type B
vent pipe and fittings must be used. Common venting is not permitted
All application and installation instructions supplied with the
power venter must be followed.
Please address all questions regarding power venter installation,
agency listings and furnace model compatibility to:
Tjernlund Products, Inc.
(800) 255-4208 or (612) 426-2993
Field Controls L.L.C.
(800) 742-8368 or (919) 522-0214
EXISTING VENT SYSTEMS
IMPORTANT RETROFIT
VENTING INSTRUCTIONS
If this furnace is a replacement installation, ALWAYS INSPECT
the existing vent system to be sure there are no obstructions,
blockages, or signs of corrosion.
When the existing furnace is removed from a venting system
serving other appliances, the venting is likely to be too large to
properly vent the remaining attached appliances.
The following steps shall be followed with each appliance that remains connected to the common venting system, while the other
appliances that remain connected to the common venting systems are not in operation.
NOTE: When the vent table permits more than one diameter
of pipe for a connector or vent, the smallest permitted diameter must be used.1. Seal any unused openings in the common venting system.
NOTE: Ensure existing venting system complies with latest addi-
tion of National Fuel Gas Code ANSI Z223.1 and all local
codes/regulations.
1. Visually inspect the venting system for proper size and horizontal pitch and determine that there is no blockage, restriction, leakage, corrosion or other deficiencies which could
cause an unsafe condition.
2. Insofar as is practical, close all building doors, windows and all
doors between the space where the appliances remaining connected to the common venting system are located. Turn on
clothes dryers and any appliance not connected to the common venting system. Turn on any exhaust fans, such as range
hoods and bathroom exhausts, so they will operate at maximum speed. Do not operate a summer exhaust fan. Close fireplace dampers.
3. Follow the lighting instructions. Place the appliance being inspected into operation. Adjust the thermostat so the appliance
will operate continuously.
4. Test for spillage at the draft hood relief opening after 5 minutes
of main burner operation. Use the flame of a match or candle,
or smoke from a cigarette, cigar, or pipe.
5. After it has been determined that each appliance that remains
connected to the common venting system properly vents
(when tested as outlined above) return doors, windows, exhaust fans, fireplace dampers and any other gas-burning appliance to their previous conditions of use.
6. If improper venting is observed during any of the above tests,
the common venting system must be resized. Refer to National
Fuel Gas Code, ANSI Z223.1.
Combustion Air

23
Gas Supply
IMPORTANT SAFETY INFORMATION
NATURAL GAS AND PROPANE
(LIQUEFIED PETROLEUM GAS / LPG)
SAFETY
GAS SUPPLY
GAS SUPPLY
GAS SUPPLY AND PIPING
!
WARNING
• FURNACES USING PROPANE GAS ARE DIFFERENT FROM NATURAL GAS MODELS. A NATURAL
GAS HEATER WILL NO T FUNCTION SAFELY ON
PROPANE AND VICE VERSA. CONVERSIONS OF
HEATER GAS TYPE SHOULD ONLY BE MADE BY
QUALIFIED INSTALLERS USING FACTORY SUPPLIED COMPONENTS. THE FURNACE SHOULD
ONLY USE THE FUEL TYPE IN ACCORDANCE
WITH LISTING ON RATING PLATE. ANY OTHER
FUEL USAGE WILL RESULT IN DEATH OR SERIOUS PERSONAL INJURY FROM FIRE AND/OR EXPLOSION.
• BOTH NATURAL GAS AND PROPANE HA VE AN
ODORANT ADDED TO AID IN DETECTING A GAS
LEAK. SOME PEOPLE MAY NOT PHYSICALLY BE
ABLE TO SMELL OR RECOGNIZE THIS ODORANT.
IF YOU ARE UNSURE OR UNFAMILIAR WITH THE
SMELL OF NATURAL GAS OR PROP ANE, ASK
YO UR LOCAL GAS SUPPLIER. OTHER CONDITIONS, SUCH AS “ODORANT F ADE,” WHICH
CAUSES THE ODORANT T O DIMINISH IN INTENSITY, CAN ALSO HIDE, CAMOUFLAGE, OR OTHERWISE MAKE DETECTING A GAS LEAK BY
SMELL MORE DIFFICULT.
• UL OR CSA RECOGNIZED FUEL GAS DETECTORS
ARE RECOMMENDED IN ALL ENCLOSED
PROPANE AND NA TURAL GAS APPLICATIONS
WHEREIN THERE IS A POTENTIAL FOR AN EXPLOSIVE MIXTURE OF FUEL GAS TO ACCUMULATE.
FUEL DETECTOR INSTALLA TION SHOULD BE IN
ACCORD ANCE WITH THE DETECTOR MANUFACTURER’S RECOMMENDATIONS AND/OR LOCAL
LAWS, RULES, REGULATIONS, OR CUSTOMS.
• BEFORE ATTEMPTING TO LIGHT THE FURNACE,
MAKE SURE TO LOOK AND SMELL FOR GAS
LEAKS. USE A SOAPY SOLUTION TO CHECK ALL
GAS FITTINGS AND CONNECTIONS.
BUBBLING AT A CONNECTION INDICATES A LEAK
THAT MUST BE CORRECTED. WHEN SMELLING TO
DETECT A GAS LEAK, BE SURE TO ALSO SNIFF
NEAR THE FLOOR. PROPANE GAS IS HEAVIER
THAN AIR AND TENDS TO COLLECT AT LOWER
LEVELS MAKING IT MORE DIFFICULT TO SMELL AT
NOSE LEVEL. NATURAL GAS IS LIGHTER THAN AIR
AND WILL RISE, POSSIBLY ACCUMULATING IN
HIGHER PORTIONS OF THE STRUCTURE.
• IF A GAS LEAK IS PRESENT OR SUSPECTED:
- DO NOT ATTEMPT TO FIND THE CAUSE Y OURSELF.
- NEVER
USE AN OPEN FLAME TO TEST FOR GAS
LEAKS. THE GAS CAN IGNITE RESULTING IN
DEATH, PERSONAL INJURY, OR PROPERTY
DAMAGE.
-DO NOTTRY TO LIGHT ANY APPLIANCE.
-DO NOTTOUCH AND ELECTRICAL SWITCH.
-DO NOTUSE ANY PHONE IN YOUR BUILDING.
- LEAVE THE BUILDING IMMEDIATELY AND CALL
THE GAS SUPPLIER FROM A NEIGHBOR’S
PHONE. FOLLOW THE GAS SUPPLIER’S INTR UCTIONS.
- IF YOU CANNOT REACH YOUR GAS SUPPLIER,
CALL THE FIRE DEPARTMENT.
- DO NOT RETURN TO THE BUILDING UNTIL AUTHORIZED BY THE GAS SUPPLIER OR FIRE DEPARTMENT.
• SHOULD OVERHEATING OCCUR OR THE GAS
SUPPLY F AIL TO SHUT OFF, TURN OFF THE MANUAL GAS CONTROL VALVE TO THE FURNACE.
• CONSULT WITH THE LOCAL BUILDING DEPARTMENT AND FUEL GAS SUPPLIER BEFORE INST ALLING THE HEA TER:
- THE INSTALLATION AND PURGING OF GAS PIPING MUST CONFORM TO LOCAL CODES, UTILITY COMPANY REQUIREMENTS, AND THE
LATEST EDITION OF NATIONAL FUEL GAS
CODE (NFGC) - ANSI Z223.1/NFPA 54.
- LP FURNACES SHOULD NOT BE INSTALLED
BELOW GRADE (IN A B ASEMENT FOR EXAMPLE) IF SUCH INSTALLATION IS PROHIBITED BY
FEDERAL, STATE, PRO VINCIAL, AND/OR LOCAL
LAWS, RULES, REGULATIONS, OR CUSTOMS.
- INSTALLATION OF A GAS PRESSURE REGULATOR MAY BE REQUIRED IN THE GAS SUPPLY
LINE. THE REGULATOR SHOULD NOT EXCEED
THE MAXIMUM SUPPLY PRESSURE LISTED ON
THE FURNACE RATING PLATE. DO NOT USE AN
INDUSTRIAL-TYPE GAS REGULATOR.
- FOLLOW ALL LOCAL CODES AND SECTION 8.3
OF NFGC WITH REGARD TO PURGING OF GAS
PIPING TO ENSURE THA T THE AIR AND/OR FUEL
GAS IN THE GAS PIPING IS PROPERLY VENTED
TO A LOCATION WHERE AN EXPLOSIVE MIXTURE CANNOT A CCUMULATE.
(Continued on next column)

24
Gas Supply
GAS SUPPLY
IMPORTANT:
Any additions, changes or conversions required for
the furnace to satisfactorily meet the application should be made
by a qualified installer, service agency or the gas supplier, using
factory-specified or approved parts.
IMPORTANT:
Connect this furnace only to gas supplied by a
commercial utility or commercial fuel provider.
IMPORTANT:
A U.L. or CSA recognized fuel gas and CO detector(s) are recommended in all applications, and their installation
should be in accordance with the detector manufacturer’s recommendations and/or local laws, rules, regulations or customs.
Install the gas piping according to all local codes, state codes and
regulations of the utility company, whichever holds jurisdiction.
If possible, run a separate gas supply line directly from the meter
to the furnace. Consult the local gas company for the location of
the manual main shut-off valve.The gas line and manual gas
valve must be adequate in size to prevent undue pressure
drop and never smaller than the pipe size to the combination
gas valve on the furnace. Refer to Table 6 for the recom mended
pipe size for natural gas and Table 7 for LP gas pipe sizes.
IMPORTANT:
It is permissible to run flexible gas connector inside
the unit to a piece of black pipe. If local codes allow the use of a
flexible gas appliance connector, always use a new listed connector. Do not use a connector which has previously serviced another
gas appliance. Massachusetts law limits flexible gas connectors to
a maximum of 36”.
Install a ground joint union outside the cabinet and within 3
feet to easily remove the control v alve assembly. Install a
manual shut-off valve in the gas line outside the furnace casing. The valve should be readily accessible to turn the gas supply
on or off. Install a drip leg in the gas supply line as close to the furnace as possible. Always use a pipe compound resistant to the
action of liquefied petroleum gases on all threaded connections.
IMPORTANT:
When making gas pipe connections, use a back-up
wrench to prevent any twisting of the control assembly and gas
valve. Do not overtighten the connection.
Any strains on the gas valve can change the position of the gas
orifices in the burners. This can cause erratic furnace operation.
IMPORTANT:
ENSURE that the furnace gas control valve not be
subjected to high gas line supply pressures.
DISCONNECT the furnace and its individual shut-off valve from
the gas supply piping during any pressure testing that exceeds
1/2 PSIG (3.48 kPa).
GAS PIPE INSTALLATION
GAS VALVE
MANIFOLD
MANIFOLD
FLAME SENSOR
FLAME SENSOR
BURNERS
BURNERS
DIRECT SPARK
IGNITOR
DIRECT
SPARK
IGNITOR
MANUAL GAS VALVE
(IN CLOSED POSITION)
UNION
DUCT
UNION
DRIP LEG
DRIP LEG
4 TO 5 FEET
ABOVE FLOOR
REQ'D BY SOME
UTILITIES
4 TO 5 FEET
ABOVE FLOOR
REQ'D BY SOME
UTILITIES
UPFLOW
HORIZONTAL
GAS VALVE
FIGURE 19
GAS PIPING INSTALLATION
MANUAL GAS VALVE
(IN CLOSED
POSITION)
GAS PIPING
!
WARNING
THIS FURNACE IS EQUIPPED AT THE FACTORY
FOR USE ON NATURAL GAS ONLY. CONVERSION
TO LP GAS REQUIRES A SPECIAL KIT IS AVAILABLE AT THE DISTRIBUTOR. FAILURE TO USE THE
PROPER CONVERSION KIT CAN CAUSE FIRE,
CARBON MONOXIDE POISONING, EXPLOSION,
PROPERTY DAMAGE, PERSONAL INJURY OR
DEATH. SEE THE CONVERSION KIT INDEX SUPPLIED WITH THE FURNACE. THIS INDEX IDENTIFIES THE PROPER LP GAS CONVERSION KIT
REQUIRED FOR EACH PARTICULAR FURNACE.

25
GAS SUPPLY (cont.)
IMPORTANT: ENSURE that the furnace gas valve is not to be
subjected to high gas line supply pressures.
DISCONNECT the furnace and its individual manual gas stop
from the gas supply piping during any pressure testing that ex-
ceeds 1/2 PSIG. (3.48 kPa).
Natural gas supply pressure must be 5" to 10.5" w.c. LP gas
supply pressure must be 11" to 13" w.c.
This pressure must
be maintained with all other gas-fired appliances in operation.
The minimum gas supply pressure to the gas valve for proper furnace input adjustments is 5" w.c. for natural gas, however 6" to 7"
is recommended. The minimum gas supply pressure is 11" w.c.
for LP gas.
GAS V AL VE
This furnace has a 24-volt gas valve. It has ports for measuring
supply and manifold gas pressure. The valve body contains a
pressure regulator to maintain proper manifold gas pressure.
A control switch is on the valve body. It can be set to only the
“ON” or “OFF” positions. The gas valve is a slow-opening valve.
See Figure 20.
When energized, it takes 2 to 3 seconds to fully open.
GAS PRESSURE
!
CAUTION
ELEVATIONS ABOVE 2000 FT. REQUIRE THAT THE
FURNACE INPUT RATING BE ADJUSTED AND THAT
THE SIZE OF THE BURNER ORIFICES BE RECALCULATED BASED ON ELEVATION AND GAS HEATING VALUE. THE BURNER ORIFICES MAY (OR MAY
NOT) NEED TO BE CHANGED. SEE THE SECTION
TITLED “HIGH ALTITUDE INSTALLATIONS” OF THIS
BOOK FOR INSTRUCTIONS.
FIGURE 20
TYPICAL GAS VALVE (HONEYWELL)
REGULATOR CAP
!
WARNING
NEVER PURGE A GAS LINE INTO THE COMBUSTION CHAMBER. NEVER USE MATCHES, FLAME
OR ANY IGNITION SOURCE FOR CHECKING LEAKAGE. FAILURE TO ADHERE TO THIS WARNING CAN
CAUSE A FIRE OR EXPLOSION RESULTING IN
PROPERTY DAMAGE, PERSONAL INJURY OR
DEATH.
TO CHECK FOR GAS LEAKAGE, USE AN APPRO VED CHLORIDE-FREE SOAP AND WATER SOLUTION, OR OTHER APPROVED METHOD.
T ABLE 6
NATURAL GAS PIPE CAPACITY TABLE (CU. FT./HR.)
Capacity of gas pipe of different diameters and lengths in cu. ft. per hr. with pressure drop of 0.3 in. and specific
gravity of 0.60 (natural gas).
Nominal Length of Pipe, Feet
Iron Pipe
Size, Inches 10 20 30 40 50 60 70 80
1/2 132 92 73 63 56 50 46 43
3/4 278 190 152 130 115 105 96 90
1 520 350 285 245 215 195 180 170
1-1/4 1,050 730 590 500 440 400 370 350
1-1/2 1,600 1,100 890 760 670 610 560 530
After the length of pipe has been determined, select the pipe size which will provide the minimum cubic feet per hour
required for the gas input rating of the furnace. By formula:
Gas Input of Furnace (BTU/HR)
Cu. Ft. Per Hr. Required =
Heating Value of Gas (BTU/FT
3
)
The gas input of the furnace is marked on the furnace rating plate. The heating value of the gas (BTU/FT
3
) may be de-
termined by consulting the local natural gas utility or the LP gas supplier.
Gas Supply

26
GAS SUPPLY (cont.)
SETTING GAS PRESSURE
The maximum gas supply pressure to the furnace must not
exceed 10.5" w.c. natural gas, or 13" w.c. LP gas.
The minimum supply gas pressure to the gas valve should be 5⬙ w.c. natural gas or 11⬙ w.c. LP gas. A properly calibrated manometer is
required for accurate gas pressure measurements.
SUPPLY GAS PRESSURE
MEASUREMENT
An inlet pressure tap is on the input side of the gas valve.
1. With gas shut off to the furnace at the manual gas valve outside the unit, remove the inlet pressure tap plug.
2. Connect a manometer to the pressure tap.
3. Turn on the gas supply and operate the furnace and all other
gas-fired units on the same gas line as the furnace.
4. Note or adjust the line gas pressure to give:
A. 5⬙ - 10.5⬙ w.c. for natural gas.
B. 11⬙ - 13⬙ w.c. for LP gas.
5. Shut off the gas at the manual gas valve and remove the
manometer and hose.
6. Replace the pressure tap plug before turning on the gas.
7. Turn on the gas supply and check for gas leaks using an approved leak detector. Do NOT
use a flame of any kind to
check for leaks. Repair any leaks and repeat.
If the supply gas line pressure is above these ranges,a high pressure in line gas regulator may be required. Consult local gas utility. With LP gas, have the LP supplier reduce the line pressure at
the regulator.
If supply gas line pressure is below these ranges, either remove
any restrictions in the gas supply piping or enlarge the gas pipe.
See Tables 6 and 7. With LP gas, have the LP supplier adjust the
line pressure at the regulator.
MANIFOLD GAS PRESSURE
MEASUREMENT
Natural gas manifold pressure should be 3.5" w.c. LP gas
manifold pressure should be 10.0" w.c. Only small variations in
gas pressure should be made by adjusting the pressure regulator.
1. With the gas to the unit shut off at the manual gas valve, remove the outlet pressure tap plug.
2. Connect a manometer to this pressure tap.
3. Turn on the gas supply and operate the furnace (apply a
heat call).
4. Note or adjust the manifold gas pressure to give:
A. 3.5⬙ w.c. for natural gas.
B. 10.0⬙ w.c. for LP gas.
5. To adjust the pressure regulator, remove the regulator cap.
(See Figure 20.)
6. Turn the adjustment screw clockwise to increase pressure,
or counterclockwise to decrease pressure.
7. Securely replace the regulator cap.
8. Shut off gas at the manual gas valve and remove the
manometer and hose.
9. Replace the pressure tap plug before turning on the gas.
10. Turn on the gas supply and apply a heat call to the furnace
then check for gas leaks using an approved leak detector.
Do NOT
use a flame of any kind to check for leaks. Repair
any leaks and repeat.
Gas Supply
!
CAUTION
ELEVATIONS ABOVE 2000 FT. REQUIRE THAT THE FURNACE INPUT RATING BE ADJUSTED AND THAT THE SIZE
OF THE BURNER ORIFICES BE RECALCULATED BASED
ON ELEVATION AND GAS HEATING VALUE. THE BURNER
ORIFICES MAY (OR MAY NOT) NEED TO BE CHANGED.
SEE THE SECTION TITLED “HIGH ALTITUDE INSTALLATIONS” OF THIS BOOK FOR INSTRUCTIONS.

27
T ABLE 7
LP GAS PIPE CAPACITY TABLE (CU. FT ./HR.)
Maximum capacity of pipe in thousands of BTU per hour of undiluted liquefied petroleum gases (at 11 inches water
column inlet pressure).
(Based on a Pressure Drop of 0.5 Inch Water Column)
Nominal Length of Pipe, Feet
Iron Pipe
Size, Inches 10 20 30 40 50 60 70 80 90 100 125 150
1/2 275 189 152 129 114 103 96 89 83 78 69 63
3/4 567 393 315 267 237 217 196 182 173 162 146 132
1 1,071 732 590 504 448 409 378 346 322 307 275 252
1-1/4 2,205 1,496 1,212 1,039 913 834 771 724 677 630 567 511
1-1/2 3,307 2,299 1,858 1,559 1,417 1,275 1,181 1,086 1,023 976 866 787
2 6,221 4,331 3,465 2,992 2,646 2,394 2,205 2,047 1,921 1,811 1,606 1,496
Example (LP): Input BTU requirement of unit, 120,000
Equivalent length of pipe, 60 ft. = 3/4" IPS required.
LP CONVERSION
LP Conversion
NOTE: The valve can be converted to use liquified petroleum
(LP) gas by replacing the pressure regulator spring with the
conversion kit spring. This LP kit spring allows the regulator
to maintain the proper manifold pressure for LP gas. See
Figure 21.
NOTE: Order the correct LP conversion kit from the furnace
manufacturer. Furnace conversion to LP gas must be performed by a qualified installer, service agency or the gas
supplier.
NOx MODELS
When converting furnaces equipped with NOx inserts to LP gas,
remove the NOx insert assemblies. Steps for removal are listed
below:
1. Turn off all electrical power and the gas supply to the furnace.
2. Remove the burner door from the furnace.
3. Remove the burner assembly – handle with care.
4. Remove the two screws attaching the NOx insert retainer
bracket to the center panel and remove NOx inserts.
5. Put the two screws back into the holes in the center panel.
6. Re-install the burner assembly.
7. Replace burner door.
8. Turn on electrical power and gas supply to the unit.
NOTE: Some NOx models may have one less NOx insert.
ORIFICE INSTALLATION
LP Gas is a manufactured gas that has consistent heating
value across most regions.
The Sea Level input should still be reduced by 4% per
thousand ft. and the orifice size must be selected based on
the reduced input selection chart in High Alt. Instruction
Section.
To change orifice spuds for either conversion to LP or for elevation:
1. Shut off the manual main gas valve and remove the
gas manifold.
2. Replace the orifice spuds.
3. Reassemble in reverse order.
4. Turn the gas supply back on and check for proper operation and manifold pressure.
5. Attach the notice label alerting the next service technician that the furnace has been converted to LP gas.
FIGURE 21
TYPICAL LP KIT CONTENTS
!
WARNING
LP TANKS FROM LOCAL LP SUPPLIER MUST NOT
BE USED TO STORE ANYTHING (SUCH AS FERTILIZER) EXCEPT LP GAS. THIS INCLUDES ALL DELIVERY VESSELS (LP TRUCKS). IF MATERIAL OTHER
THAN LP GAS IS USED IN THE SAME
VESSELS/TANK AS THE LP GAS, THE LP GAS CAN
BECOME CONTAMINATED AND DAMAGE THE FURNACE. THIS WILL VOID THE MANUF A CTURER’S
WARRANTY. CONTACT THE SUPPLIER TO MAKE
SURE FERTILIZER IS NOT USED IN THE SAME
TANKS USED TO STORE AND DELIVER LP GAS.
GAS PRESSURE

28
Electrical Wiring
ELECTRICAL CONNECTIONS
Before proceeding with the electrical connections, be certain that
the voltage, frequency and phase corresponds to that specified
on the furnace rating plate. For single furnace application, maximum over-current protection is 15 amperes.
Use a separate fused branch electrical circuit containing a properly sized fuse or circuit breaker. Run this circuit directly from the
main switch box to an electrical disconnect that is readily accessible and located near the furnace (as required by code). Connect
from the electrical disconnect to the junction box on the left side
of the furnace, inside the blower compartment. For the proper
connection, refer to the appropriate wiring diagram located on the
inside cover of the furnace control box and in these instructions.
NOTE: The electrical junction box may be moved to the right side
if necessary. A knockout is provided. Seal the opposite hole with
plug provided.
NOTE: L1 (hot) and L2 (neutral) polarity must be observed when
making field connections to the furnace. The ignition control may
not sense flame if L1 and L2 are reversed. Make all electrical
connections in accordance with the latest edition of the National
Electrical Code ANSI/NFPA70.
These may be obtained from:
National Fire Protection Association, Inc.
Batterymarch Park
Quincy, MA 02269
REVERSING THE ELECTRICAL
CONNECTION (JUNCTION BOX)
If the line voltage electrical needs to be moved to the opposite
side of the furnace, the following steps should be taken:
1. The furnace must NOT be electrically connected to line voltage prior to reversing the electrical connection.
2. Disconnect the wires from the door switch.
3. Remove the junction box from the furnace cabinet wall by removing the two screws that hold it to the cabinet. Leave the
wires connected to the junction box.
4. Remove 7/8” plug from hole opposite j-box location. Drill 2 @
3/16” Ø holes in the jacket. NOTE: Dimples/marks are provided in the sheet metal for correct drilling location.
5. Move the junction box to the opposite side of the cabinet. Install using the two screws removed in step 3 above. Note
that all screws penetrating the junction box must be blunt –
no sharp tipped screws can be used.
6. Replace the plug from the opposite of the furnace (the new jbox location) to the old j-box location and install qty=2 1/4”
plugs from parts bag in empty screw holes in old location of
j-box into the mounting screw holes in the old junction box location.
ELECTRICAL WIRING
ELECTRICAL WIRING
!
WARNING
THE CABINET MUST HAVE AN UNINTERRUPTED
GROUND ACCORDING TO THE LATEST EDITION OF
THE NATIONAL ELECTRICAL CODE, ANSI/NFPA70
OR LOCAL CODES THAT APPLY. DO NOT USE GAS
PIPING AS AN ELECTRICAL GROUND. A GROUND
SCREW IS PROVIDED IN THE JUNCTION BOX. FAILURE TO DO SO CAN CAUSE ELECTRICAL SHOCK
RESULTING IN PERSONAL INJURY OR DEATH.
!
WARNING
THIS FURNACE IS EQUIPPED WITH A BLOWER
DOOR SAFETY SWITCH. DO NOT DISABLE THIS
SWITCH. FAILURE TO FOLLOW THIS WARNING
CAN RESULT IN ELECTRICAL SHOCK, PERSONAL
INJURY OR DEATH.
FIGURE 22
ST-A1220-05
!
WARNING
TURN OFF ELECTRIC POWER AT FUSE BOX OR
SERVICE PANEL BEFORE MAKING ANY ELECTRICAL CONNECTIONS. FAILURE TO DO SO CAN
CAUSE ELECTRICAL SHOCK RESULTING IN PERSONAL INJURY OR DEATH.
LOCKING
TABS

35
High Altitude
HIGH ALTITUDE
34" 80 Plus furnaces installed above 2,000 ft. require the furnace
to be de-rated 4% per thousand feet.
IMPORTANT:
Factory installed orifices are calculated and sized
based on a sea level Natural Gas heating value of 1050 BTU per
cubic ft.
NOTE: Orifices are available through your local distributor.
Reference Table 8 for approximate orifice sizing.
The following are examples of orifice sizing using the National
Fuel Gas Code Appendix F:
For a simplified estimation of orifice size based on gas heating
value and elevation, Table 8 may be used. However, calculations
are the best method.
Example: 900 BTU/ft
3
Regional Natural Gas Heating Value
I/H = Q
25000 / 900 = 27.78 ft
3
I = Sea Level input (per burner): 25000
H = Sea Level Heating Value: 900
Q = 27.78 ft3Natural Gas per hour.
From Table F.1 of
National Fuel Gas Code Handbook, 2002
(3.5ⴖ
w.c. column).
Orifice required at Sea Level: #40
From Table F.4 of
National Fuel Gas Code Handbook,
Orifice required at 5000 ft. elevation (4% de-rate per thousand ft): #42
Orifice required at 8000 ft. elevation (4% de-rate per thousand ft.):
#44
Example: 1050 BTU/ft3 Regional Natural Gas Heating Value
I / H = Q
25000 / 1050 = 23.81ft
3
I = Sea Level input (per burner): 25000
H = Sea Level Heating Value: 1050
Q = 23.81 ft
3
Natural Gas per hour.
From Table F.1 of
Natural Fuel Gas Code Handbook, 2002
(3.5⬙
w.c. column).
Orifice required at Sea Level: #43
From Table F.4 of
National Fuel Gas Code Handbook, 2002
Orifice required at 5000 ft. elevation (4% de-rate per
thousand ft.): #45
Orifice required at 8000 ft elevation (4% de-rate per
thousand ft): #47
ORIFICE ORDERING INFORMATION
Orifice sizes are selected by adding the 2-digit drill size required in
the orifice part number. Drill sizes available are 39 through 64;
metric sizes available 1.10mm (-90) and 1.15mm (-91):
Orifice Part Number 62-22175-(drill size)
Example:
# 60 drill size orifice required
Part # 62-22175-60
NATURAL GAS AT HIGH ALTITUDES
!
WARNING
INSTALLATION OF THIS FURNACE AT ALTITUDES ABOVE
2000 FT (610 m) SHALL BE IN ACCORD ANCE WITH
LOCAL CODES, OR IN THE ABSENCE OF LOCAL CODES,
THE NATIONAL FUEL GAS CODE, ANSI Z223.1/NFPA 54.
!
CAUTION
ELEVATIONS ABOVE 2000 FT. REQUIRE THAT THE FURNACE INPUT RATING BE ADJUSTED AND THAT THE SIZE
OF THE BURNER ORIFICES BE RE-CALCULATED BASED
ON ELEVATION AND GAS HEATING VALUE. THE BURNER
ORIFICES MAY (OR MAY NOT) NEED TO BE CHANGED.
THE FOLLOWING EXAMPLES SHOW HOW TO DETERMINE IF AN ORIFICE CHANGE WILL BE NECESSARY
AND HOW TO DETERMINE THE NEW ORIFICE SIZE.

36
High Altitude
TABLE 8
SUPPLEMENTAL ORIFICE SIZE CHART
HIGH ALTITUDE
NATURAL GAS AT HIGH ALTITUDES (cont.)
NATURAL GAS ORIFICE SELECTION BASED ON HEATING VALUE & ELEVATION*
Notes:
1. All (-)80+ units are factory equiped with orifices sized for 1050 sea level heating value gas.
2. Local utilities adjust the sea level heating value of gasses used at higher elevations to compensate for appliance operation at altitude.
Installer must be aware of the local heating value (sea level standard) to use the chart below.
3. This chart is based on the National Fuel Gas Code (NFGC) Annex F based on natural gas with a secific gravity of 0.60
4. The recommended orifices below allow the furnace to operate within 10% of design rate. However, NFGC calculations are the best
method.
5. Furnace operation is optimized when operating at design rate. Installer is responsible to verify rate.
6. This table applies to 80+ models only with 25,000BTU/Burner. DO NOT
Grey Cells Indicate Factory
Orifice Size
1,000-1,100
Gas Heating
Value
(BTU's/ft
@ Sea
Level**
*Table is derived from Appendix of the National Fuel Gas Code . To determine the correct orifice for your installation consult the National
Fuel Gas Code tables F.1 and F.4
**Be sure to use sea level heating value. When requesting the heating value from a local utility, it must be converted to sea level equivalent
in order to use this table.
900-999
3
)
800-899
700-799
Sea Level
to 1,999'
2,000' to
2,999'
43 44 44 44 45 45 46 47 47 48
42 42 43 43 43 44 44 45 46 47
42
41
40
39
38
37
37
36
35
3,000' to
3,999'
42 43 43 43 44 44 45 46 47
42 42 42 43 43 44 44 45 46
41
40 41 41 42 42 43 43 44 44
39 40 41 41 42 42 43 43 44
38 39 39 40 41 42 42 43 43
38 39 39 40 41 42 42 43 43
37 38 38 39 40 41 41 42 43
36 36 37 37 38 39 40 41 42
4,000' to
4,999'
42
USE THIS CHART FOR ANY 90+ FURNACE MODEL.
ELEVATION
5,000' to
5,999'
42 42 43 43 44 44 45
6,000' to
6,999'
7,000' to
7,999'
8,000' to
8,999'
9,000' to
9,999' 10,000'

38
Start-Up Procedure
START-UP PROCEDURES
SEQUENCE OF OPERATIONS
This furnace is equipped with a direct ignition control. Each time
the room thermostat calls for heat, the ignitor lights the main
burners directly. See the lighting instructions on the furnace.
TO START THE FURNACE
1. Remove the burner compartment control access door.
2. IMPORTANT: Be sure that the manual gas control has been
in the “OFF” position for at least five minutes. Do not attempt
to manually light the main burners.
3. Turn off the furnace electrical power and set the room thermostat to its lowest setting.
4. Turn the gas control to the “ON” position or move the gas
control lever to the “On” position.
5. Replace the burner compartment control access door.
6. Turn on the furnace electrical power.
7. Set the room thermostat to a point above room temperature
to light the main burners.
8. After the burners are lit, set the room thermostat to a desired
temperature.
9. Operate gas heat for a minimum period of 15 minutes and adjust input rate (page 42) and observe condensate system for
leaks. Correct leaks and set rate, shutdown furnace and repeat until no leaks in condensate system can be detected.
TO SHUT DOWN THE FURNACE
1. Set the room thermostat to its lowest setting and wait for furnace to shut down.
2. Remove the burner compartment control access door.
3. Shut off the gas to the main burners by turning the gas control
to the “OFF” position.
SEQUENCE OF OPERATION
UT ELECTRONIC CONTROLS
Integrated Controls with Direct Spark Ignition.
1. Each time the thermostat “W” (Heating) contacts close, the
furnace control checks to make sure the pressure switch is
open. Next the induced draft blower (inducer) begins a prepurge cycle.
2. The air proving negative pressure switch(es) closes.
3. After the 30-second pre-purge, the gas valve opens for an
8-second trial for ignition.
4. The spark igniter is energized to light the gas burners and
stays energized for the up to 7 seconds after the gas
valve opens.
5. 8 seconds after the gas valve opens the remote flame sensor must prove flame ignition f or
one second
using the
process of flame rectification. If the burners don’t light, the
system goes through another ignition sequence. It does this
up to four times before entering a 1-hour lockout.
6. The main blower starts approximately 20 seconds after the
burners ignite.
7. When the thermostat “W” (Heat Call) ends, the gas valve
closes, flame is extinguished, the induced draft blower stops
after a 10-second post-purge, and the negative pressure
switch opens.
8. The main blower continues until timed off by the setting on
the integrated furnace control board.
Sequence if the system doesn’t light or doesn’t sense flame:
1. On a call for heat, the furnace control checks to make sure
the pressure switch is open. Next the control runs the inducer
for 30 seconds to prepurge.
2. After the 30-second pre-purge, the gas valve opens for an 8second trial for ignition. The inducer continues and the igniter
stays energized.
3. If flame is not sensed during the 8th second after the gas
valve opens, the gas valve closes, and the igniter de-energizes.
4. The inducer stops (may take up to 20 seconds for inducer fan
to stop rotating) and the control verifies that the pressure
switch has opened. Once the open pressure switch is confirmed, the control begins the next ignition cycle by energizing
the inducer for a pre-purge of 30 seconds. After a 30-second
pre-purge period, the gas valve is energized and the control
looks for a flame signal for up to 8 seconds. If no flame is
sensed, the cycle is repeated up to 4 times before entering a
1-hour lockout.
!
WARNING
SHOULD OVERHEATING OCCUR OR THE GAS SUPPLY
FAIL TO SHUT OFF, CLOSE THE MANUAL GAS VALVE
FOR THE APPLIANCE BEFORE SHUTTING OFF THE
ELECTRICAL SUPPLY. FAILURE TO DO SO CAN CAUSE
AN EXPLOSION OR FIRE RESULTING IN PROPERTY
DAMAGE, PERSONAL INJURY OR DEATH.

39
Fault Codes
FAULT CODES
FAULT CODES
DIAG NOSTICS AND FAULT CODES
All furnace controls come standard with a 7-segment diagnostic
display. During standby mode with no fault codes present, the
display will read “0” (zero). During normal thermostat heating,
cooling or continuous fan operation, a letter will be displayed to
describe the mode of operation as follows:
C = Cooling or Heat-Pump Heat Operation
F = Continuous Fan Operation
H = Gas Heating Operation
When the control senses a fault present, it will display a code to
help in diagnoses. A list of normal operating codes and potential
fault codes follows:
The method for displaying a two-digit fault is to display the first
(most significant) digit for one second immediately followed by
the second digit – which is also displayed for a duration of one
second. A ½ second pause is then displayed. Cycle repeats until
the fault is cleared. Each fault is flashed (displayed) a minimum
of two times even if the fault condition has cleared before the
fault can be displayed twice.
DUAL FAULTS DISPLAYED
In some cases when two faults are present simultaneously, both
faults are displayed. These exceptions for dual faults are noted
below.
Sequence of display:
A. The first two-digit fault will be displayed once as described
above.
B. The upper-most horizontal segment of the seven-segment
display is energized for ½ second.
C. The second two-digit fault is displayed once as described
above.
D. The upper-most horizontal segment of the seven-segment
display is energized for ½ again.
This cycle repeats until one fault is gone (in which case the remaining fault will be displayed as described above) or both faults
are gone or otherwise as noted below:
1. When a failed ignition has occurred four times in a row, the
control enters one-hour lockout and fault codes
“10”
and
“11”
will be displayed alternately as described above.
2. When flame is lost five times in a row, the control enters onehour lockout and fault codes
“10”
and
“13”
will be displayed
alternately as described above (A-D).
3. While the control is in one-hour lockout due to an unexpected
flame, the fault codes
“14”
(unexpected flame) and
“10”
(soft
lockout) will be displayed alternately at the seven-segment
display as described above (A-D).
4. While the control has entered a one-hour lockout after declaring a dead blower after the main limit control has been open
for more than 150 seconds, the fault codes
“61”
(Non-opera-
tional blower) and
“10”
(soft lockout) will be displayed alternately as described above (A-D). Note: the dead blower fault
and associated one-hour lockout will occur up to four times in
one heat call. Upon declaring this fault for the fourth time in
one heat call, the control will enter hard lockout.
5. When the main limit has been open during a gas heat call for
more than 150 seconds and has not yet re-closed, the fault
codes
“61”
(Non-operational blower) and
“22”
(open limit)
will be displayed alternately as described above (A-D) until
the limit re-closes.
The higher priority fault code will be displayed until the condition
is corrected then the lower priority fault code will display (provided the fault condition is still present).
CODE Description
0 STANDBY
C COMPRESSOR ON
(COOLING OR HEAT-PUMP HEAT)
H GAS HEAT ON
F CONTINUOS FAN ON
10 1 HOUR LOCKOUT
11 FAILED IGNITION
12 LOW FLAME SENSE
13 FLAME LOST
14 UNEXPECTED FLAME
20 TWINNING FAULT
22 MAIN LIMIT OR HALC OPEN
26 LINE AND NEUTRAL REVERSED
33 MRLC (MANUAL RESET LIMIT
CONTROL) (AKA ROLL-OUT) OPEN
55 PRESSURE SWITCH STUCK
CLOSED WHEN SHOULD BE OPEN
57 PRESS SWITCH STUCK OPEN
WHEN SHOULD BE CLOSED
61 BLOWER FAULT – BLOWER
UNABLE TO RUN
93 INTERNAL CONTROL FAULT

Airflow
AIRFLOW
The importance of proper air flow over the heat exchanger cannot
be over emphasized.
One of the most common causes of heat exchanger failure is overheating due to low air flow. An air flow table is located inside the
blower door and on the following pages.
TEMPERATURE RISE CHECK
To determine if the air flow is correct, make a temperature rise
check.
1. Insert a thermometer in the supply air duct as close to the furnace as possible yet ot of a direct line from the heat exchanger. See Figure 31.
2. Insert a thermometer in the return air duct as close to the furnace as possible.
3. Operate the furnace.
4. When the thermometer in the supply air duct stops rising (approximately five minutes), subtract the return air temperature
from the supply air temperature. The difference is the temperature rise.
5. Compare the measured temperature rise to the approved temperature rise range listed on the furnace name plate. See Figure 32.
If the measured temperature rise is above the approved range, either the air flow is too low or the manifold pressure needs to be adjusted. More air must be moved by speeding up the blower, by
removing restrictions in the duct system, or by adding more supply
or return air duct. If the measured temperature rise is below the approved range, either the air flow is too much or the manifold pressure needs to be adjusted. Use lower speed tap on the multi-speed
blower.
IMPORTANT:
The measured temperature rise should be in the
middle of the range.
IMPORTANT: Some high-efficiency filters have a greater than normal resistance to airflow. This can adversely affect furnace operation. BE SURE TO CHECK AIRFLOW if using any filter other than
factory-provided filter.
!
CAUTION
IT IS IMPORTANT THAT EACH DUCT SYSTEM BE SIZED
AND INSTALLED FOR THE SPECIFIC APPLICATION BY
PROPERLY APPLYING THE APPROPRIATE INDUSTRY ACCEPTED STANDARD. IF LESS THAN MINIMUM STANDARDS ARE APPLIED, THE EQ UIPMENT USER COULD
EXPECT TO EXPERIENCE HIGHER UTILITY BILLS, MAJOR
COMPONENT F AILURE, VARYING DEGREES OF AIR
NOISE OR OTHER UNSATISFACTORY ISSUES, OVER
WHICH THE MANUFACTURER HAS NO CONTROL.
FIGURE 31
TEMPERATURE RISE MEASUREMENT
FIGURE 32
TYPICAL FURNACE NAME PLATE
!
WARNING
THE MEASURED TEMPERATURE RISE SHOULD BE AS
CLOSE TO THE MIDDLE OF THE STA T ED RANGE AS POSSIBLE. FOR EXAMPLE, IF THE RISE RANGE IS 40 TO 70°F
(4.5°-21°C), THE MIDDLE OF THE RISE RANGE IS 55°F
(12.8°C). IN ALL APPLICATIONS, THE INSTALLER MUST ADJUST THE TEMPERA TURE RISE TO THIS “MIDDLE” POINT
AS CLOSELY AS POSSIBLE. ALSO, THE TEMPERATURE
RISE SHOULD NEVER BE ABOVE OR FALL BELOW THE
ST ATED RANGE. DOING SO COULD CAUSE DAMAGE TO
THE HEA T EXCHANGER OR INTERMITTENT OPERATION.
THIS COULD CAUSE INJURY OR DEATH AND WILL VOID
THE MANUF ACTURER’S WARRANTY FOR THIS PR ODUCT.
45
ENERGY
PERFORMANCE
VERIFIED
R801PA075417MSA
W00000000
25
55

46
BLO WER SPEED SELECTIONS
The UT Electronic Controls control boards have four quick connect terminals for connecting the motor speed leads. These are:
1. FAN SPEED* — motor runs on this speed when the thermostat is in the “FAN” position.
2. COOL — connect desired cooling speed.
3. HEAT — connect desired heating speed.
4. HEAT/COOL* — connect desired speed when heating and
cooling speed are the same.
5. If heating and continuous speed are the same, jump across
“FAN” and “HEAT” terminals.
See Table 10 for instructions for setting the blower “OFF” timings.
GAS FURNACE (DIRECT DRIVE)
INSTRUCTIONS FOR CHANGING
BLO WER SPEED
The blower motor is wired for blower speeds required for normal
operation as shown.
If additional blower speed taps are available (leads connected to
“M1” and “M2” on the electronic control), speeds may be changed
if necessary to fit requirements of the particular installation. Reconnect the unused motor leads to “M1” or “M2.” Check motor
lead color for speed designation.
Heating speeds should not be reduced where it could cause the
furnace air temperature to rise to exceed the maximum outlet air
temperature specified for the unit.
!
CAUTION
DO NOT CONNECT ANY MO TOR SPEEDS TO “HEAT” OR
“COOL” IF YOU USE THE “HEAT/COOL” TERMINAL. DOING
SO WILL DAMAGE THE BLOWER MOTOR. UNUSED
MOT OR WIRE TAPS MUST BE CONNECTED TO PARKING
TERMINALS M1 AND M2 OF THE IFC, OR PROPERLY INSULATED.
!
WARNING
DISCONNECT THE ELECTRICAL SUPPL Y T O THE FURNACE BEFORE ATTEMPTING TO CHANGE THE BLOWER
SPEED. FAILURE TO DO SO CAN CAUSE ELECTRICAL
SHOCK RESULTING IN SEVERE PERSONAL INJURY OR
DEATH.
Low 823 803 787 732 718 691 651 593
Med. Lo 1030 1018 1006 976 929 897 850 808
Med. Hi 1129 1132 1112 1087 1054 1028 971 919
High 1361 1353 1331 1297 1264 1232 1164 1117
Low 1229 1200 1181 1155 1120 1078 1013 970
Med. Lo 1308 1267 1266 1233 1204 1176 1113 1062
Med. Hi 1553 1542 1516 1491 1451 1417 1358 1306
High 1969 1924 1893 1840 1803 1728 1657 1570
Low 1209 1182 1131 1112 1051 976 929 867
Med. Lo 1438 1420 1386 1350 1320 1293 1248 1186
Med. Hi 1902 1883 1844 1817 1753 1700 1636 1547
High 2071 2037 2001 1962 1905 1856 1807 1709
Low 1358 1354 1331 13091 1250 1224 1154 1089
Med. Lo 1541 1517 1476 1453 1416 1371 1339 1277
Med. Hi 1799 1774 1746 1712 1691 1629 1554 1495
High 2015 1989 1929 1902 1862 1815 1742 1665
Low 1411 1395 1370 1334 1310 1252 1220 1150
Med. Lo 1606 1579 1569 1537 1499 1468 1407 1346
Med. Hi 1889 1891 1849 1828 1764 1717 1659 1609
High 2178 2160 2105 2067 2024 1976 1916 1832
TABLE 12
AIR FLOW PERFORMANCE – (-)801S/(-)801P & (-)(-)80MSS/(-)(-)80MSP SERIES MODELS
Model
Motor HP
Blower Size,
IN.
CFM Air Delivery
External Static Pressure, ” W.C.
Speed Tap 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
(-)801SA050314MSA
(-)801PA050314MSA
(-)(-)80MSS050A30SA
(-)(-)80MSP050A30SA
1/3
11 x 6
(-)801SA075417MSA
(-)801PA075417MSA
(-)(-)80MSS075B30SA
(-)(-)80MSP075B30SA
(-)801SA100521MSA
(-)801PA100521MSA
(-)(-)80MSS100C40SA
(-)(-)80MSP100C40SA
(-)801SA125524MSA
(-)801PA125524MSA
(-)(-)80MSS125D50SA
(-)(-)80MSP125D50SA
1/2
11 x 7
1/2
11 x 10
3/4
11 x 10
(-)801SA150524MSA
(-)801SA150524MSA
(-)(-)80MSS150D50SA
(-)(-)80MSP150D50SA
3/4
11 x 10
NOTE: Shaded data is factory heating tap.
Airflow

47
Safety Features
SAFETY FEATURES
LIMIT CONTROL/HALC
The high limit cut-off temperature is set at the factory and cannot
be adjusted. The temperature setting prevents the air temperature leaving the furnace from exceeding the maximum outlet air
temperature, which, if exceeded, will shut the furnace down.
There are several reasons for a limit switch to open and almost
always involve low airflow through the furnace.
1. A dirty or restricted air filter.
2. A dirty or restricted cooling coil.
3. Undersized or restricted return air system.
4. Undersized or restricted supply air system.
5. A problem affecting the main blower:
A. A wrong speed tap selection.
B. Failing motor bearings.
C. Low voltage to the motor.
D. Dirty blower wheel.
E. Wrong motor rotation.
F. Blower wheel slipping on the
F. motor shaft.
G.
Bad run capacitor
.
6. Overfiring the furnace with too much gas pressure.
7. Ventilation problems.
8. Failed blower motor.
FLAME ROLL-OUT SAFETY SWITCHES
Furnaces are equipped with safety switches to protect against
flame roll-out conditions in the burner compartment, which, if
tripped, will terminate the heating cycle. In the event of a flame
roll-out condition, the switch will shut the furnace down. Switches
for the furnaces are located on either side of the burner cover
plate. If a switch is tripped, it must be manually reset. DO NOT
jumper or reset this switch. If this switch should trip, a qualified installer, service agency or the gas supplier should be called to diagnose and/or correct the source of tripping. If this unit is
mounted in a closet, the door must be closed when making this
check.
PRESSURE SWITCH
This furnace is equipped with a normally-open pressure switch
that monitors pressure conditions within the furnace vent system
during the heating cycle.
There are several reasons for the pressure switch not to close.
1. An inoperative induced draft blower.
2. A loose or leaky pressure switch hose.
3. A blockage in the vent.
4. Severe downdrafts canceling the draft from the inducer fan.
5. A leaky gasket at the induced draft blower.
6. Improperly sized or installed vent.
The pressure switch contacts must open before the unit can go
through another heating cycle.
See diagnostic chart in this book for diagnostic recommenda-
tions.
!
WARNING
DO NOT BYPASS, JUMPER, OR REMOVE ANY SAFETY
SWITCH FROM THE FURNACE CONTROL CIRCUIT. IF A
SAFETY SWITCH CAUSES THE FURNACE TO SHUT
DOWN OR OPERATE INTERMITTENTLY, IT IS AN INDICATION OF A POTENTIAL SAFETY HAZARD THAT MUST BE
ADDRESSED BY A QUALIFIED TECHNICIAN, SERVICE
AGENCY OR THE GAS SUPPLIER. DO NOT RESET
SAFETY CONTROLS WITHOUT CORRECTIVE ACTION
AND/OR VERIFICATION OF PROPER SAFE OPERATION
BY A QUALIFIED INSTALLER, SERVICE AGENCY OR THE
GAS SUPPLIER.
REPLACE ANY SAFETY CONTROL COMPONENT ONLY
WITH IDENTICAL OEM REPLACEMENT PARTS. WHEN A
NEW SAFETY SWITCH IS INSTALLED, IT MUST BE
TESTED FOR A MINIMUM OF 15 MINUTES WITH THE
FURNACE OPERATING AT MAXIMUM INPUT RATE AND
WITH BOTH BLOWER AND BURNER DOOR INSTALLED.
IF THE FURNACE IS INSTALLED IN A CLOSET, THE
CLOSET DOOR MUST ALSO BE CLOSED FOR THIS
TEST. REPEAT THE TEST AT THE MINIMUM INPUT RATE
IF THE FURNACE IS A MULTI-STAGE FURNACE.

49
ANNUAL INSPECTION
MAINTENANCE
• The furnace should operate for many years without ex-
cessive scale build-up in the flue passageways. However,
it is recommended that a qualified installer, service
agency, or the gas supplier annually inspect the flue passageways, the vent system and the main burners for continued safe operation. Pay particular attention to
deterioration from corrosion or other sources.
• IMPORTANT: It is recommended that at the beginning
and at approximately half way through the heating season, a visual inspection be made of the main burner
flames for the desired flame appearance by a qualified installer, service agency or the gas supplier. If the flames
are distorted and/or there is evidence of back pressure,
check the combustion and ventilation air system for blockage. If there is carbon and scale in the heat exchanger
tubes, the heat exchanger assembly should be replaced.
• IMPORTANT: It is recommended that at the beginning of
the heating season, the flame sensor be cleaned with
fine steel wool or Scotch Bright Pad by a qualified installer, service agency or the gas supplier.
• IMPORTANT: It is recommended that an annual inspection and cleaning of all furnace markings be made to assure legibility. Attach a replacement marking, which can
be obtained through the distributor, if any are found to be
illegible or missing.
REPLA CEMENT PARTS
Please visit www.myrheem.com/myruud.com for replacement parts information.
DIAGNOSTICS
Refer to Figure 33 for determining cause of unit problems.
WIRING DIAGRAM
Figure 34 is a complete wiring diagram for the furnace.
A wiring diagram is also available on the unit.
SYSTEM OPERATION INFORMATION
ADVISE THE CUSTOMER
1. Keep the air filters clean. The heating system will operate better, more efficiently and more economically.
2. Arrange the furniture and drapes so that the supply air
registers and the return air grilles are unobstructed.
3. Close doors and windows. This will reduce the heating
load on the system.
4. Avoid excessive use of kitchen exhaust fans.
5. Do not permit the heat generated by television, lamps
or radios to influence the thermostat operation.
6. Except for the mounting platform, keep all combustible
articles 3 feet from the furnace and vent system.
7. IMPORTANT: Replace all blower doors and compart-
ment covers after servicing the furnace. Do not operate the unit without all panels and doors securely in
place.
8. Explain the advantages of continuous fan operation to
the customer.
!
WARNING
HOLES IN THE VENT PIPE OR HEAT EXCHANGER
CAN CAUSE TOXIC FUMES TO ENTER THE HOME,
RESULTING IN CARBON MONOXIDE POISONING
OR DEATH. THE VENT PIPE OR HEAT EXCHANGER
MUST BE REPLACED IF THEY LEAK.
Maintenance

50
Diagnostics
FIGURE 33
DIAGNOSTICS FLOWCHART
DISCONNECT POWER BEFORE SERVICING.
SERVICE MUST BE BY A TRAINED, QUALIFIED
WARNING
LINE VOLTAGE
HAZARDOUS VOLTAGE
Always verify gas valve inlet and outlet gas
NOTE:
pressure .
START
1) Set FAN switch to “AUTO ”
2) Set thermostat to call for heat (set temp. differential to greater than 10
PREPURGE
Does the IDM Energize ?
SERVICE TECHNICIAN.
CONNECTIONS
IDM Runs for 30 sec. pre-purge ?
F
NO
YES
CHECK BLINK CODES
- Check for open limit or limit circuit.
YES
NO
FLAME (AMBER) LED CODES
OFF = No Flame Presen t
RAPID BLINK = Unexpected Flame
SLOW BLINK = Marginal Flame Sense
STEADY ON = Normal Flame Sense
“FAULT DISPLAYED ?”
24V on W to IFC?
- Check line voltage at IDM.
- Check wires and connections between IDM and IFC.
- Ensure line voltage on IDM pins of IFC connector .
- Check IDM capacitor (90+ only) .
Does IDM Run for 60 sec. and then off for Five minutes
YES
NO
NO
YES
Check IFC*.
Does IDM run
YES
indefinately .
“ATTEND TO FAULT”
- Check thermostat in “heat” mode,
batter y, wire, and connections.
NO
NO
YES
KEY TO ABBREVIATIONS
IBM = Indoor Blower Motor
IDM = Induced Draft Motor
IFC = Integrated Furnace Control
PS = Pressure Switch(es)
SE = Spark Electrode
DSI = Direct-Spark Ignition
- For Twinned units, check that both IFCs are set for “TWIN” and wires
are connected between “TWIN” terminals .
- Check IFC*.
- For twinned units, ensure transformers are in phase.
(if out of phase, flame LED will be dim) .
- For non-twinned units, ensure “TWIN” is in the single (OFF) position.
- For Twinned units – ensure both IFC‘s have same part number .
- Check PS, PS Hoses, and wires.
- Check for blocked vent, excessive vent length or elbows, or
blocked heat exchanger .
- Check IDM wired correctly .
- Ensure against excessive wind, which can open pressure switch.
- Check for intermittent P.S. operation.
- Check switches and hoses for water or moisture.
CODE DESCRIPTION
O
C
H
F
10
11
12
13
14
20
22
26
33
55
57
58
59
61
93
H
Standby
Compressor on (cooling or heat pump heat)
Gas heat on
Continuous fan on
1 hour lockout
Failed ignition
Low flame sense
Flame lost
Unexpected flame
Twinning fault
Main limit open / HALC limit open
Line and neutral reversed
Mrlc (man. Reset limit cont.)(aka roll-out open)
Pres. Switch stuck closed, should be open
Pres. Switch stuck open, should be closed
Water Sensed Circuit Open
Water Sensed
Blower fault - blower unable to run
Internal control fault
- Check PS contact s
- Check wires for short.
- Check IFC*.
- Check switches and hoses fo r
water or moistur e
G
F
IGNITION TRIAL
Spark Ignitor Sparking?
IBM “ON” DELAY
Does Main Burner Light and stay lit?
Does IBM start on heat speed 20 seconds
after burners light ?
STEADY HEAT
TROUBLESHOOTING GUIDE
INTEGRATED FURNACE CONTROL (IFC)
possibilities, including the ground connection, before replacing the IFC.
NOTE: Most failures are not due to the IFC. Double check all othe r
Does main burner remain lit until
heat call ends?
Always verify gas valve inlet and outlet gas pressure.
NOTE:
Does thermostat maintain reasonable room
temperature near setpoint ?
END HEAT CALL
Set thermostat to off position (W to C = ØV)
POST-PURGE
Does gas valve shut off immediately?
Does IDM shut off after ten second post-purge?
IBM “OFF” DELAY
Does IBM shut off after a max. of 3 min?
STEADY OFF
Heat-mode troubleshootin g
END
FOR DIRECT SPARK IGNITION
- Check ignitor connected .
- Check ignitor wires.
NO
YES
YES
YES
YES
YES
YES
YES
YES
- Check ignitor for fractures or cracking
- Check ignitor placement .
- If problem persists, check IFC*.
**
Is the gas valve energized?
NO
NO
- Check line voltage between “HEAT” and “NEUTRAL” on IFC.
- Check wires, connections, and continuity between IFC and IBM.
- Check IBM capacitor .
- Check IBM.
NO
D
Is Limit circuit open
Note: IFC Status LED should be blinking a Fault Code.
CHECK:
BLOCKED DRAIN - (fault “59” should be present)
AIRFLOW
- ensure no restrictions, such as dirty filte r, dampers, closed registers, etc.
LIMITS
- ensure good wire and connections between IFC and all limits. Make sur e
limits are not open when circulating air temperature is within a specified range.
- ensure rollouts or overtemperature limits do not need to be reset. Make
ROLLOUTS
sure no flame rollout in burner compartment due to blocked flu or heat exchanger.
OVERFIRE
- ensure furnace is not overtemperature (temp rise is above stated range).
Check gas valve, proper orifice size, gas pressure, etc.
Ensure thermostat is properly placed and not improperly affected by
NO
registers, fans, sunlight, heat through walls, pipes, or wires in walls .
Double check - Is W off at IFC?
NO
NO
(W to C = ØV?)
Ensure TSTAT is not in “FAN” position.
Is disply flashing a fault code
Is “FLAME” LED blinking or steady-on ?
NO
NO
or
YES
NO
GO TO
Check IFC*.
YES
opening and closing?
YES
“FLAME” LED BLINKING
OR STEADY ON
E
If “E” did not
resolve issue
Voltage present at gas valve?
Fault Code Present
GO TO
I
” did not
If “
I
resolve issue.
NO NO
Is the IFC sensing a good flame: NOTE:
Flame sense l ight sho uld be steady -on
when burners are lit. If flame LED blinking,
or off, flame sense is low or absent.
- Check IFC*.
YES
SEE FAULT CODES
REPEAT THIS PROCEDURE UNTIL TROUBLE-FREE OPERATION IS OBTAINED.
- Check gas supply and manifold pressure.
- Ensure L1 and Neutral not swapped on IFC and junction box.
- Check igniter alignment .
- Check orifice or other restrictions to gas flo w.
- Check flame sense rod (clean with scotch brite pad).
- Check flame carry over .
- Check wires, continuity , and connection between IFC and gas valve.
- Ensure 24 V between appropriate pins on connector of IFC.
Ensure manual switch on valve is in the “ON” position.
- Did a pressure switch open during ignition trial? If yes, go to F
- Did a limit open during ignition trial? If yes, go to D
I
NOTE: If IFC goes into lockout (“STATUS LED will blink code “1”), shut
off main power to unit, wait 30 seconds and then reset power .
NO
CHECK:
- g rounding on IFC and unit.
- check for proper polarity between L1 & neutral.
- flame sense rod (clean if necessar y).
- wire continually between flame sense rod and appropriate pin of
connector on IFC
- flame carries across all burners, and all burners stay lit.
PROBLEM
PRESENT
- Check heat anticipator setting. Furnace may need an isolation relay.
- Check installation instructions under section titled “Isolation Relay” for
STILL
details .
- Verify correct furnace sizing.
- Check gas valve.
NO
YES
PS dropping out ?
*Most failures are not due to the IFC. Doubl e
check all other possibilities, including the
ground connection or wire connections, before
replacing the IFC.
**System will attempt to light 4 times. Voltage
is present at gas valve for only 7 seconds during each trial for ignition. The entire system will
go into a 1 hour lockout after 4 attempts.
GO TO
F
YES
Check IFC*
E
ST-A1194-23-03