Field Installed Option Accessories ..............30
Electronic Air Cleaner........................30
Humidifier .................................30
Filter .....................................30
RXGW-B01 Chimney Adapter .................30
Four Inch Flue Adapter.......................30
11 TWINNING ................................32
Furnace Twinning Installations.................32
Control Boards .......................... 33-34
12 HIGH ALTITUDE ...........................35
Natural Gas at High Altitudes..................35
LP Gas at High Altitudes .....................37
13 STARTUP PROCEDURES ...................38
Sequence of Operation ......................38
14 DIAGNOSTICS AND FAULT CODES ..........39
15 LOCKOUT ................................40
16 FIELD SELECTIONS & ADJUSTMENTS .......41
Field Selections – Dipswitches.................41
17 FAULT CLEAR ............................42
18 FAULT 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 PARTS ....................49
24 TROUBLESHOOTING.......................50
30 WIRING DIAGRAM .........................51
IMPORTANT: TO INSURE PROPER INSTALLATION AND OPERATION OF THIS PRODUCT, COMPLETELY READ ALL INSTRUCTIONS PRIOR TO ATTEMPTING TO ASSEMBLE, INSTALL, OPERATE, MAINTAIN OR REPAIR THIS PRODUCT. UPON
UNPACKING OF THE FURNACE, INSPECT ALL PARTS FOR DAMAGE PRIOR TO INSTALLATION AND START-UP.
2
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.
FIGURE 1
FURNACE COMPONENTS
13
14
15
16
20
17
18
1
2
3
The 80% single stage constant torque 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
B-1 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
National 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.
12
ITEM
11
10
9
NO.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
8
19
20
DESCRIPTION
DOOR SWITCH
TRANSFORMER
JUNCTION BOX
LOW VOLTAGE TERMINAL
SOLID METAL BASE PAN
FURNACE CONTROL
CONTROL MOUNTING PLATE
BLOWER
IGNITER
GAS VALVE
INDUCED DRAFT BLOWER
4” FLUE ADAPTER (OPTIONAL)
COMBUSTION AIR INLET
MAIN LIMIT
COMBUSTION AIR DIFFUSER
MAIN PRESSURE SWITCH
BURNER
FLAME SENSOR
HEAT ASSISTED LIMIT CONTROL (HALC)
OVER TEMPERATURE SWITCH
General Information
19
4
7
6
5
ST-A1220-20-00
ST-A1220-20-00
3
GENERAL INFORMATION (cont.)
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
General Information
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.
MATERIAL INFORMATION
All manufacturer products meet current Federal OSHA Guidelines for safety. Most consumers are aware that products present
safety and health risks, when improperly used, handled and
maintained. More details are available at the Websites for OSHA
(Occupational Safety and Health Administration), at www.osha.
gov.
EFFICIENCY TESTING NOTICE
For purposes of verifying or testing efficiency ratings, the
test procedure in Title 10 Appendix N to Subpart B of
Part 430 (Uniform Test Method for Measuring the Energy
Consumption of Furnaces and Boilers) and the clarifying
provisions provided in the AHRI Operations Manual for
Residential Furnaces that were applicable at the date of
manufacture should be used for test set up and performance.
4
Installation Instructions remain with the furnace as a reference guide to the servicing contractor. We recommend
that performance and installation data be recorded for future reference on this sheet to meet service and warranty obligations so that job site information is available when required.
______ Correct clearance to combustibles (record clearance)
______ Correct clearance for service (at front) (record clearance)
______ Remove shipping bracket from blower
DUCT STATIC PRESSURE
______ in. w.c. on heating speed (record static pressure)
______ in. w.c. on cooling speed (record static pressure)
______ Air temperature rise in heat (record air temperature rise)
______ Air temperature rise in cool (record air temperature rise)
VENTING
______ Correct vent pipe diameter and length (according to NFGC tables) _________________ Vent connection size
______ Correct venting material (according to NFGC tables)
______ Correct lining for masonry chimneys
______ Adequate clearance from combustibles
______ Proper negative pressure reading in the vent
______ Vent pipe secured to induced draft blower housing
COMBUSTION AIR
______ Proper source of combustion air
______ Correct combustion air opening size
______ Optional attic combustion air pull
Checklist
______ Non-attic combustion air pull
5
SAFETY INFORMATION
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 MANU-
FACTURER’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
Safety Information
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 TO THE FURNACE RATING
PLATE.
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.
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.
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.
6
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.
SAFETY
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 INSTALLATION;
-FURNACE OPERATING UNDER THERMOSTAT CON-
TROL;
-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 REQUIRED
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.
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.
FIGURE 2
MIGRATION OF DANGEROUS SUBSTANCES, FUMES, AND ODORS INTO
LIVING SPACES
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.
Adapted from Residential Duct Diagnostics and Repair, with permission of Air Conditioning
Contractors of America (ACCA).
7
LOCATION REQUIREMENTS
GENERAL INFORMATION
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.
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
crawl space installation, horizontal furnaces may be installed
on combustible wood flooring or by using support brackets.
See Figure 3.
Location
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.
8. IMPORTANT: This furnace is shipped with a blower motor
support bracket. This bracket must be removed before operating furnace. Remove (2) screws from front of blower and
slide bracket off motor shaft.
WARNING
!
THIS FURNACE IS NOT APPROVED OR RECOMMENDED
FOR INSTALLATION ON ITS BACK, WITH ACCESS
DOORS FACING UPWARDS.
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.
WARNING
!
DO NOT LIFT THE UNIT BY THE HEAT EXCHANGER
TUBES. DOING SO CAN DAMAGE THE HEAT EXCHANGER ASSEMBLY.
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 (61 cm) is recommended in front of all furnaces.
NOTE:Use recommended 24” (61 cm) clearance if ac-
cessibility clearances are greater than fire protection clearances.
ACCESSIBILITY CLEARANCES, WHERE GREATER, MUST
TAKE PRECEDENCE OVER FIRE PROTECTION CLEARANCES.
8
LOCATION REQUIREMENTS
NOTE:
GENERAL INFORMATION (cont.)
WARNING
UPFLOW AND HORIZONTAL FURNACES ARE DESIGN-
CERTIFIED FOR INSTALLATION ON COMBUSTIBLE
FLOORS. NOTE, HOWEVER, THAT FURNACES MUST
NOT BE INSTALLED DIRECTLY ON CARPETING, TILE OR
OTHER COMBUSTIBLE MATERIAL OTHER THAN WOOD
FLOORING. INSTALLATION ON A COMBUSTIBLE MATERIAL CAN RESULT IN FIRE, CAUSING PROPERTY DAMAGE, PERSONAL INJURY OR DEATH.
FIGURE 3
HORIZONTAL LEFT ORIENTATION DEPICTED IN ILLUSTRATION.
HORIZONTAL RIGHT ORIENTATION IS SIMILAR IN INSTALLATION.
AIR FLOW
ST-A1220-03
WARNING
!!
COMBUSTIBLE MATERIAL MUST NOT BE PLACED
ON OR AGAINST THE FURNACE JACKET. THE AREA
AROUND THE FURNACE MUST BE KEPT CLEAR AND
FREE OF ALL COMBUSTIBLE MATERIALS INCLUDING
GASOLINE AND OTHER FLAMMABLE VAPORS AND
LIQUIDS. PLACEMENT OF COMBUSTIBLE MATERIALS
ON, AGAINST OR AROUND THE FURNACE JACKET CAN
CAUSE AN EXPLOSION OR FIRE RESULTING IN PROPERTY DAMAGE, PERSONAL INJURY OR DEATH. THE
HOMEOWNER SHOULD BE CAUTIONED THAT THE FURNACE AREA MUST NOT BE USED AS A BROOM CLOSET
OR FOR ANY OTHER STORAGE PURPOSES.
Location
9
BOTTOM
TOP
LEFT SIDEFRONTRIGHT SIDE
GAS
CONNECTION
ELECTRICAL CONNECTION
LINE VOLTAGE
ELECTRICAL CONNECTION
LOW VOLTAGE
OPTIONAL
GAS CONNECTION
OPTIONAL LOW
VOLTAGE WIRING
OPTIONAL LINE VOLTAGE
WIRING
A
I
R
F
L
O
W
RETURN
AIR
SUPPLY
AIR
HOT
ST-A1220-04
MODELABCDEFRIGHT SIDEBACKTOPFRONTVENT
51413 27/3210 5/8①11 1/21 7/804②0136③85 lbs.
717 1/216 11/3212 3/8①152 1/203②0136③105 lbs.
102119 27/3214 1/8①18 1/22 1/2000136③120 lbs.
1224 1/223 11/3215 7/8①222 1/2000136③140 lbs.
1524 1/223 11/3215 7/8①222 1/2000136③150 lbs.
① MAY REQUIRE 3" TO 4" OR 3" TO 5" ADAPTER.
4" ADAPTER INCLUDED WITH (-)801P UNITS.
② MAY BE 0" WITH TYPE B VENT.
③ MAY BE 1" WITH TYPE B VENT.
LEFT SIDE
REDUCED CLEARANCE (IN.)
SHIP
WGTS.
FIGURE 4
UPFLOW/HORIZONTAL DIMENSIONS
Ship.
REDUCED CLEARANCE (IN.)
Back Top Front Vent
¿ May require 3” to 4” or 3” to 5” adapter.
4” adapter optional.
¿ May be 0” with type B vent.
¿ May be 1” with type B vent.
*See furnace speck sheet for availability.
Left Right
/8 0 4¿ 0 1 3 6¿ 85 lbs.
/2 0 3¿ 0 1 3 6¿ 105 lbs.
/2 0 0 0 1 3 6¿ 120 lbs.
/2 0 0 0 1 3 6¿ 120 lbs.
/2 0 0 0 1 3 6¿ 140 lbs.
1
1
7
/2 1
/2 2
1
1
/8 ¿11
/8 ¿15 2
/8 ¿18
5
3
1
/2 0 0 0 1 3 6¿ 150 lbs.
1
1
1
/2 2
1
/8 ¿18
/8 ¿22 2
/8 ¿22 2
1
7
7
ST-A1220-04
Location
/32 10
/32 12
/32 14
/32 14
/32 15
27
11
27
/2 16
1
CLEARANCE TO COMBUSTIBLE MATERIAL (INCHES)
UPFLOW/HORIZONTAL MODELS
Input A B C D E F
Side Side Wgts.
050 14 12
075 17
075 21 19
/32 15
27
11
11
/2 23
/2 23
1
1
100 21 19
125 24
150 24
10
DUCTING
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.
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.
WARNING
!
ZONING SYSTEMS ARE NOT DIRECTLY SUPPORTED
IN THIS MANUAL. IF A THIRD PARTY SYSTEM IS USED
REFER TO THE MANUFACTURER OF THAT PRODUCT
FOR INSTALLATION AND OPERATION INSTRUCTIONS.
ZONING SYSTEMS USED ON THIS PRODUCT MUST
HAVE SENSORS TO PREVENT FURNACES AND/OR
HEATING ELEMENTS FROM CYCLING ON INTERNAL
LIMIT CONTROLS. THE ZONING SYSTEM MUST NOT
ALLOW THE EVAPORATOR COILS AND/OR HYDRONIC
COILS TO FREEZE.
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.
UPFLOW 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.
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 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 SPACE
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.
Ducting
11
DUCTING
FIGURE 5
NOTE:
NOTE:
SOLID BASE PLATE PROVIDED WITH 80%
SOLID BASE PLATE PROVIDED WITH (-)801PMODELS ONLY.
SINGLE STAGE CONSTANT TORQUE
MODELS ONLY.
WHEN SOLID BASE PLATE IS USED . TAPE AROUND BOTTOM FLANGES OF CABINET
WHEN SOLID BASE PLATE IS USED, TAPE
BEFORE THE UNIT IS INSTALLED.
AROUND BOTTOM FLANGES OF CABINET BEFORE THE UNIT IS INSTALLED.
SOLID BASE FLANGE
FITS UNDER
CABINET BOTTOM
FIGURE 6
Ducting
LIFT UP, PULL OUT
1. REMOVE 2 SCREWS, LIFT BASE UP, SLIDE FORWARD TO REMOVE.
2. INSTALLATION IS REVERSE OF REMOVAL.
** VERIFY REAR FLANGE IS SEALED PROPERLY AS SHOWN IN DETAIL.
CUT OUT USING
EMBOSSED ANGLES
AS A GUIDE
FOR PROPER SIZE
23” X 14”
FIGURE 7
ST-A1220-10-X0
ST-A1220-10
A
I
R
F
L
O
W
CUT OUT USING
EMBOSSED ANGLES
AS A GUIDE
FOR PROPER SIZE
23” X 14”
12
ST-A1220-08
ST-A1220-11-X0
ST-A1220-11
DUCTING
NOTE:
HORIZONTAL LEFT ORIENTATION DEPICTED IN ILLUSTRATION.
HORIZONTAL RIGHT ORIENTATION IS SIMILAR IN INSTALLATION.
AIR FLOW
NOTE:
DO NOT BLOCK FURNACE ACCESS WITH
SUPPORT RODS, ALLOW SPACE FOR
PROPER SERVICE MAINTIENCE OR
REPLACEMENT OF THE HEAT EXCHANGER
AND BLOWER ASSEMBLY .
HORIZONTAL UNITS
1. Position the unit to minimize long runs of duct or runs of
duct with many turns and elbows.
2. Unit can be mounted left or right side airflow configuration.
3. Position the unit on adequate supports or by using
support brackets (see Figure 8) and connect supply
plenum.
4. If summer air conditioning is desired, position the indoor coil on the supply air side of the unit. Insure that
no air can bypass this coil.
5. Secure the four angle brackets to the return air opening. See Figure 9. Connect the return air ducting to the
return air opening at the top of the unit. Make the connection air tight to prevent entraining combustion gases
from an adjacent fuel-burning appliance.
NOTE: Do not block furnace access with support rods.
Maintain clearances recommended in Figure 8. Allow
enough space for proper service maintenance or replacement of the heat exchanger and blower assembly.
FIGURE 8
HORIZONTAL FURNACE INSTALLED W/SUPPORT BRACKETS
FIGURE 9
HORIZONTAL RETURN AIR DUCT
(LEFT-HAND AIRFLOW POSITION SHOWN)
AIRFLOW
RETURN
REAR VIEW
FOUR ANGLE BRACKETS, SHIPPED WITH 80% SINGLE STAGE
CONSTANT TORQUE UNITS, CAN BE INSTALLED HORIZONTALLY.
THESE BRACKETS MAY BE USED TO SECURE THE RETURN AIR
DUCT TO A HORIZONTAL UNIT.
ST-A1220-03
Ducting
13
COMBUSTION AND VENTILATION AIR
COMBUSTION AIR REQUIREMENTS
IMPORTANT: This is not a direct vent furnace. Review venting
instructions before installing.
WARNING
!
Combustion Air
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.
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
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.
Combustion air requirements are determined by whether the
furnace is in an open (unconned) area or in a conned 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 unconned
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 conned 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.
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.
14
COMBUSTION AND VENTILATION AIR (cont.)
TABLE 8: MINIMUM FREE AREA OPENING REQUIRED FOR A FURNACE LOCATED IN A CONFINED SPACE USING INDOOR AIR FOR COMBUSTION.
Input (BTUH)
Free Area for Each
Opening (sq inches)
50,000100
75,000100
100,000100
125,000130
150,000150
COMBUSTION AIR REQUIREMENTS: CONFINED AND
UNCONFINED SPACES
Combustion Air
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.
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 identied in the National Fuel Gas Code.
Combustion air requirements are determined by whether the
furnace is in an open (unconned) area or in a conned space
such as a closet or small room.
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.
FURNACE LOCATED IN AN
UNCONFINED SPACE
USING INDOOR AIR FOR COMBUSTION:
An unconned 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 species minimum space requirements and a few ex-
amples 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 conned space.
TABLE 1: MINIMUM SPACE REQUIREMENTS
TABLE 7: MINIMUM SPACE REQUIREMENTS
FOR UNCONFINED SPACE, NON-DIRECT VENT
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
150,000 7,500 940 32 x 30
Minimum
Space
(Cubic Ft)
Minimum Area
with 8
Ceilings (sq )
Typical Room
Size w/ 8'
Ceilings ( x )
FURNACE LOCATED IN A CONFINED
SPACE
A conned space is dened as any space for a given furnace
input rating which is smaller than that which is specied in Table
1 as minimum for an “unconned” space. If the space is less than
that specied in this table, the space is dened as “conned”.
If the space is small enough to be designated as “conned”,
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 conned 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 replace, exhaust fan or other device that may produce negative pressure.
If combustion air is taken from the heated area, the open-
ings 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 conned space.
TABLE 8: MINIMUM FREE AREA
TABLE 2: MINIMUM FREE AREA
OPENING REQUIRED FOR A
OPENING REQUIRED FOR A
FURNACE LOCATED IN A
FURNACE LOCATED IN A
CONFINED SPACE USING
B. USING OUTDOOR AIR FOR COMBUSTION:
IMPORTANT: Do not take air from an attic space that is
The conned space must communicate with the outdoors in
METHOD 1:
Two permanent openings, one located within 12 inches of
CONFINED SPACE USING
INDOOR AIR FOR COMBUSTION.
INDOOR AIR FOR COMBUSTION.
Free Area for Each
Input (BTUH)
50,000 100
75,000 100
100,000 100
125,000 130
150,000 150
equipped with power ventilation.
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.
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.
Opening (sq inches)
15
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 THROUGH A VERTICAL VENT DUCT.*
Total Input for
ALL Gas
Appliances
(BTUH)
Free Area for
Each Opening
when 2 Separate
Openings are
used (sq inches)
Round Pipe Duct
Diameter (Vercal
Duct Only) (inches)
50,000 13 5
75,000 19 5
100,000 25 6
125,000 32 8
150,000 38 8
TABLE 11: MINIMUM FREE AREA REQUIRED FOR AN OPENING (WHEN O NE OPENING IS USED) WITH A FURNACE:
1. LOCATED IN A CONFINED SPACE
2. USING OUTDOOR AIR FOR COMBUSTION
3. COMMUNICATING DIRECTLY TO THE *
Total Input for
ALL Gas
Appliances
(BTUH)
Free Areafor an
Opening when1
Opening isused
(sq inches)
Round Pipe Duct
Diameter(inches)
50,00025 6
OUTSIDE.
COMBUSTION AND VENTILATION AIR (cont.)
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 THROUGH A VERTICAL VENT DUCT.*
Total Input for
ALL Gas
Appliances
(BTUH)
Free Areafor
Each Opening
when2 Separate
Openingsare
used (sq inches)
Round Pipe Duct
Diameter (Vercal
Duct Only) (inches)
50,00013 5
75,00019 5
100,00025 6
125,00032 8
150,00038 8
TABLE 10: 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 HORIZONTAL DUCT.
Total Input for
ALL Gas
Appliances
(BTUH)
Free Area for
Each Opening
when 2 Separate
Openings are
used (sq inches)
Round Pipe Duct
Diameter
(Horizontal Duct
Only) (inches)
50,000 25 6
75,000 38 8
100,000 50 8
125,000 63 10
150,000 75 10
TABLE 11: MINIMUM FREE AREA REQUIRED FOR AN OPENING (WHEN O NE OPENING IS USED) WITH A FURNACE:
1. LOCATED IN A CONFINED SPACE
2. USING OUTDOOR AIR FOR COMBUSTION
3. COMMUNICATING DIRECTLY TO THE *
Total Input for
ALL Gas
Appliances
(BTUH)
Free Areafor an Opening when1
Opening isused
(sq inches)
Round Pipe Duct
Diameter(inches)
50,00025 6
75,00038 8
100,00050 8
125,00063 10
150,00075 10
OUTSIDE.
TABLE 11: MINIMUM FREE AREA REQUIRED FOR AN OPENING (WHEN O NE OPENING IS USED) WITH A FURNACE:
1. LOCATED IN A CONFINED SPACE
2. USING OUTDOOR AIR FOR COMBUSTION
3. COMMUNICATING DIRECTLY TO THE *
Total I nput for
ALL Gas
Appliances
(BTUH)
Free Area for an
Opening when 1
Opening is used
(sq inches)
Round Pipe Duct
Diameter (inches)
50,000 25 6
75,000 38 8
100,000 50 8
125,000 63 10
150,000 75 10
OUTSIDE.
),*85($,5)520+($7('63$&(
COMBUSTION AIR REQUIREMENTS: CONFINED AND
UNCONFINED SPACES
TABLE 3: MINIMUM FREE AREA REQUIRED
FOR EACH OPENING (WHEN TWO OPENINGS
ARE USED) WITH A FURNACE:
1. LOCATED IN A CONFINED SPACE
Combustion Air
2. USING OUTDOOR AIR FOR COMBUSTION
3. COMMUNICATING DIRECTLY TO THE
3. OUTSIDE THROUGH AN OPENING OR
3. THROUGH A VERTICAL DUCT.
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 species 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 hori-
zontal 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
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.
16
TABLE 5: MINIMUM FREE AREA REQUIRED
FOR AN OPENING (WHEN ONE OPENING IS
USED) WITH A FURNACE:
1. LOCATED IN A CONFINED SPACE
2. USING OUTDOOR AIR FOR COMBUSTION
3. COMMUNICATING DIRECTLY TO THE
3. OUTSIDE.
12). Table 4 species 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: