Bryant 120 User Manual

312A

2 --- S t a ge D e lux e
I n d u ce d --- C o m b u s ti o n
4---Way Multipoise Furnace

Installation, Start--up, Operating and

Service and M a int e nanc e

Instructions Series 120/C

SAFETY CONSIDERATIONS 2........................

INTRODUCTION 3..................................

CODES AND STANDARDS 5..........................

Safety 5...........................................

General Installation 5................................

Combustion and Ventilation Air 5......................

Duct Systems 5.....................................

Acoustical Lining and Fibrous Glass Duct 5...............

Gas Piping and Gas Pipe Pressure Testing 5...............

Electrical Connections 5..............................

Venting 5.........................................

ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS

PROCEDURE 5.....................................

LOCATION 6.......................................

AIR FOR COMBUSTION AND VENTILATION 8.........

INSTALLATION 10..................................

UPFLOW INSTALLATION 10......................

DOWNFLOW INSTALLATION 11...................

HORIZONTAL INSTALLATION 11..................

FILTER ARRANGEMENT 15.......................

AIR DUCTS 15...................................

GAS PIPING 18..................................

ELECTRICAL CONNECTIONS 21..................

VENTING 26....................................

START--UP, ADJUSTMENT, AND SAFETY CHECK 35.....

General 35........................................

Start--Up Procedures 35..............................

Adjustments 36.....................................

Check Safety Controls 40.............................

Checklist 41.......................................

SERVICE AND MAINTENANCE PROCEDURES 45.....

Introdution 46....................................

Care and Maintenance 46...........................

Sequence of Operation 51...........................

Wiring Diagrams 54...............................

Troubleshooting 54................................

ama

ISO 9001:2000

CERTIFIED

REGISTERED

NOTE: Read the entire instruction manual before starting the
installation.

Portions of the text and tables are reprinted from NFPA 54/ANSI
Z223.1--2006E, with permission of National Fire Protection
Association, Quincy, MA 02269 and American Gas Association,
Washington DC 20001. This reprinted material is not the
complete and official position of the NFPA or ANSI on the
referenced subject, which is represented only by the standard in
its entirety.

28-7/8"

25-1/4"

22-9/16"

JUNCTION BOX
LOCATION

WIRE ENTRY

3-15/16"

LEFT HAND GAS

ENTRY

7/8" DIA. ACCESSORY

21-5/8"

BOTTOM INLET

24"

CASING

1-11/16"

24-7/8"

5-1/2"

4-13/16"

8-9/16"

ALTERNATE

JUNCTION BOX

VENT OUTLET

5 PLACES (TYP)

3-3/4"

2-7/16"
1-5/16"

1-1/8"

A

D

F

E

13/16"

LOCATIONS (TYP)

5-1/2"

11/16"

AIRFLOW

19"

OUTLET

1/2" DIA. K.O.THERMOSTAT
WIRE ENTRY

1-3/4" DIA.RIGHT HAND
GAS ENTRY

7/8" DIA. K.O. WIRE ENTRY

7/8" DIA. ACCESSORY

1-1/2"

22-1/16"

SIDE INLET

13/16"

11/16"

14-7/8"

1-1/4"

1"

312A

26-1/8"

(FLUE COLLAR)

5-15/16"

7/8" DIA

ACCESSORY

NOTES:

1. Two additional 7/8-in. diameter holes are located in the top plate.

2. Minimum return-air openings at furnace, based on metal duct. If flex duct is used, see flex duct manufacturer’s recommendations for equivalent diameters.
a. For 800 CFM-16-in. round or 14 1/2 x 12-in. rectangle.
b. For 1200 CFM-20-in. round or 14 1/2 x 19 1/2-in. rectangle.
c. For 1600 CFM-22-in. round or 14 1/2 x 22-in. rectangle.
d. For airflow requirements above 1800 CFM, see Air Delivery table in Product Data literature for specific use of single side inlets. The use of both side inlets
a combination of 1 side and the bottom, or the bottom only will ensure adequate return air openings for airflow requirements above 1800 CFM.

1/2" DIA THERMOSTAT

33-5/16"

11/16"

NOTES:

1. Two additional 7/8---in. diameter holes are located in the top plate.

2. Minimum return --- air openings at furnace, based on metal duct. If flex duct is used, see flex duct manufacturer’s recommendations for equivalent
diameters.
a. For 800 CFM---16--- in. round or 14 1/2 x 12--- in. rectangle.
b. For 1200 CFM---20 ---in. round or 14 1/2 x 19 1/2--- in. rectangle.
c. For 1600 CFM---22 ---in. round or 14 1/2 x 22--- in. rectangle.
d. For airflow requirements above 1800 CFM, see Air Delivery table in Product Data literature for specific u se of single side inlets. The use of both sidein­lets, a combination of 1 side and the bottom, or the bottom only will ensure adequate return air openings for airfl ow requirements above 1800 CFM.

Fig. 1 -- Dimensional Drawing

7-3/4"

9-5/8"

11-1/2"

A04037

SAFETY CONSIDERATIONS

!

WARNING

FIRE, EXPLOSION, ELECTRICAL SHOCK, AND
CARBON MONOXIDE POISONING HAZARD

Failure to follow this warning could result in dangerous
operation, serious injury, death, or property damage.

Improper installation, adjustment, alteration, service,
maintenance, or use could cause carbon monoxide
poisoning, explosion, fire, electrical shock, or other
conditions which may cause personal injury or property
damage. Consult a qualified service agency, local gas
supplier, or your distributor or branch for information or
assistance. The qualified service agency must use only
factory--authorized and listed kits or accessories when
modifying this product.

!

CAUTION

FURNACE RELIABILITY HAZARD

Improper installation or misapplication of furnace may
require excessive servicing or cause premature component
failure.

Application of this furnace should be indoors with special
attention given to vent sizing and material, gas input rate,
air temperature rise, unit leveling, and unit sizing.

Installing and servicing heating equipment can be hazardous due
to gas and electrical components. Only trained and qualified

personnel should install, repair, or service heating equipment.

Untrained personnel can perform basic maintenance functions
such as cleaning and replacing air filters. All other operations
must be performed by trained service personnel. When working
on heating equipment, observe precautions in literature, on tags,
and on labels attached to or shipped with furnace and other safety
precautions that may apply. These instructions cover minimum
requirements and conform to existing national standards and
safety codes. In some instances, these instructions exceed certain
local codes and ordinances, especially those that may not have
kept up with changing residential construction practices. We
require these instructions as a minimum for a safe installation.

!

CAUTION

CUT HAZARD

Failure to follow this caution may result in personal injury.

Sheet metal parts may have sharp edges or burrs. Use care
and wear appropriate protective clothing, safety glasses and
gloves when handling parts and servicing furnaces.

Wear safety glasses and work gloves. Have fire extinguisher
available during start--up and adjustment procedures and service
calls.

This is the safety--alert symbol

. When you see this symbol
on the furnace and in instructions or manuals, be alert to the
potential for personal injury.

Understand the signal words DANGER, WARNING, and
CAUTION. These words are used with the safety--alert symbol.
DANGER identifies the most serious hazards which will result in
severe personal injury or death. WARNING signifies a hazard
which could result in personal injury or death. CAUTION is used
to identify hazards which may result in minor personal injury or

2

Table 1 – Dimensions (In.)

A

FURNACE SIZE

045--- 08/024045 14--- 3/16 12--- 9/16 12--- 11/16 9--- 5/16 4 116 16
045--- 12/036045 14--- 3/16 12--- 9/16 12--- 11/16 9--- 5/16 4 119 16
070--- 08/024070 14--- 3/16 12--- 9/16 12--- 11/16 9--- 5/16 4 120 16
070--- 12/036070 14--- 3/16 12--- 9/16 12--- 11/16 9--- 5/16 4 124 16
070--- 16/048070 17--- 1/2 15--- 7/8 16 11 --- 9/16 4 138 16
090--- 14/042090 17--- 1/2 15--- 7/8 16 11 --- 9/16 4 136 16
090--- 16/048090 21 19--- 3/8 19 --- 1/2 13---5/16 4 151 20
090--- 20/060090 21 19--- 3/8 19 --- 1/2 13---5/16 4 156 20
110--- 12/036110 17--- 1/2 15--- 7/8 16 11 --- 9/16 4 144 16
110--- 16/048110 21 19--- 3/8 19 --- 1/2 13---5/16 4 158 20
110--- 22/066110 21 19--- 3/8 19 --- 1/2 13---5/16 4 163 20
135--- 16/048135 21 19--- 3/8 19 --- 1/2 13---5/16 4† 163 20
135--- 22/066135 24--- 1/2 22--- 7/8 23 15 --- 1/16 4† 174 24
155--- 20/060155 24--- 1/2 22--- 7/8 23 15 --- 1/16 4† 181 24

* 5” or 6” vent connector may be required in some cases.
{ 135 and 155 size furnaces require five---inch or larger vents. Use a 4---5 or 4---6 inch vent adapter between furnace and vent connector.

CABINET

WIDTH

(IN.)

D

SUPPLY--- AIR

WIDTH (IN.)

E

RETURN---AIR

WIDTH (IN.)

product and property damage. NOTE is used to highlight
suggestions which will result in enhanced installation, reliability,
or operation.

1. Use only with type of gas approved for this furnace. Refer
to the furnace rating plate 2. Install this furnace only in a

2. Install this furnace only in a location and position as
specified in the “Location” section of these instructions.

3. Provide adequate combustion and ventilation air to the
furnace space as specified in “Air for Combustion and
Ventilation” section.

4. Combustion products must be discharged outdoors.
Connect this furnace to an approved vent system only, as
specified in the “Venting” section of these instructions.

5. 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 the “Gas Piping” section.

6. Always install 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 “Start--Up, Adjustments, and Safety
Check” section. See furnace rating plate.

7. 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. See “Air Ducts”
section.

8. A gas-- fired furnace for installation in a residential garage
must be installed as specified in the warning box in the
“Location” section.

9. The furnace may be used for construction heat provided
that the furnace installation and operation complies with
the first CAUTION in the LOCATION section of these
instructions.

10. These Multipoise Gas--Fired Furnaces are CSA (formerly
A.G.A. and C.G.A.) design--certified for use with natural
and propane gases (see furnace rating plate) and for
installation in alcoves, attics, basements, closets, utility
rooms, crawlspaces, and garages. The furnace is
factory--shipped for use with natural gas. A CSA (A.G.A.
and C.G.A.) listed accessory gas conversion kit is required

F

C.L. TOP AND

BOTTOM FLUE

COLLAR (IN.)

FLUE

COLLAR*

(IN.)

SHIP WT. (LB)

11. See Fig. 2 for required clearances to combustible
construction.

12. Maintain a 1--in. clearance from combustible materials to
supply air ductwork for a distance of 36 inches
horizontally from the furnace. See NFPA 90B or local
code for further requirements.

13. These furnaces SHALL NOT be installed directly on
carpeting, tile, or any other combustible material other
than wood flooring. In downflow installations, factory
accessory floor base MUST be used when installed on
combustible materials and wood flooring. Special base is
not required when this furnace is installed on
manufacturer’s Coil Assembly Part No. CD5 or CK5, or
when Coil Box Part No. KCAKC is used. See Fig. 2 for
clearance to combustible construction information.

INTRODUCTION

The Series 120/C 4--way multipoise Category I fan--assisted
furnace is CSA (formerly A.A.A.. and C.G.A.) design--certified.
A Category I fan--assisted furnace is an appliance equipped with
an integral mechanical means to either draw or force products of
combustion through the combustion chamber and/or heat
exchanger. The furnace is factory--shipped for use with natural
gas. This furnace is not approved for installation in mobile
homes, recreational vehicles, or outdoors.

These furnaces shall not be installed directly on carpeting, tile, or
any other combustible material other than wood flooring. For
downflow installations, a factory accessory floor base must be
used when installed on combustible materials and wood flooring.
This special base is not required when this furnace is installed on
the manufacturer’s coil assembly, or when the manufacturer’s coil
box is used. See Fig. 2 for clearance to combustible material
information.

This furnace is designed for minimum continuous return--air
temperature of 60_F db or intermittent operation down to 55_F
db such as when used with a night setback thermostat. Return-- air
temperature must not exceed 80_F db. Failure to follow these
return-- air temperature limits may affect reliability of heat
exchangers, motors, and controls. (See Fig. 3.)

For accessory installation details, refer to the applicable
instruction literature.

NOTE: Remove all shipping brackets and materials before
operating the furnace.

to convert furnace for use with propane gas.

FILTER

MEDIA
CABINET
SIZE (IN.)

312A

3

312A

INSTALLATION

MINIMUM INCHES CLEARANCE TO COMBUSTIBLE CONSTRUCTION

DISTANCE MINIMALE EN POUCES AUX CONSTRUCTIONS COMBUSTIBLES

This forced air furnace is equipped for use with

natural gas at altitudes 0-10,000 ft (0-3,050m).

An accessory kit, supplied by the
manufacturer, shall be used to convert to propane
gas use or may be required for some natural gas
applications.

This furnace is for indoor installation in a
building constructed on site.

This furnace may be installed on combustible

flooring in alcove or closet at minimum clearance
as indicated by the diagram from combusitble
material.

This furnace may be used with a Type B-1 Vent

and may be vented in common with other gas
fired appliances.

Cette fournaise à air pulsé est équipée
pour utilisation avec gaz naturel et altitudes
comprises entre 0-3,050m (0-10,000 pi).

Utiliser une trousse de conversion, fournie par
le fabricant, pour passer au gaz propane ou pour
certaines installations au gaz naturel.

This furnace is approved for UPFLOW, DOWNFLOW, and
HORIZONTAL installations.

Cette fournaise est approuvée pour l 'installation HORIZONTALE
et la circulation d 'air VERS LE HAUT et VERS LE BAS.

Clearance arrows
do not change with
furnace orientation.

0"

B

A

A

C

R

K

R

I

È

R

E

E

D

I

S

É

T

Ô

C

0"

*

1"

Les fléches de dégagement

l 'orientation de la fournaise.

TOP / PLE NUM

DESSUS / CHAMBRE D'AIR

E

C

E

A

S

N

I

A

R

U

N

F

R

U

T

FO

N

O

T

R

N

F

A

V

A

F

R

O

A

N

V

T

A

N

T

3"

Cette fournaise est prévue pour être
installée dans un bâtiment construit sur place.

Cette fournaise peut être installée sur
un plancher combustible dans une alcôve ou
dans un garde-robe en respectant le minimum
d'espace libre des matériaux combustibles, tel

´

indiqué sur le diagramme.

qu

Cette fournaise peut être utilisée avec un

´

évacuation de Type B-1 ou connectée

conduit d
au conduit ommun d 'autres appareils à gaz.

Vent Clearance to combustibles:

For Single Wall vents 6 inches (6 po).
For Type B-1 vent type 1 inch (1 po).

Dégagement de l´évent avec combustibles:

Pour conduit d´évacuation à paroi simple 6 po (6 inches).
Pour conduit d

BOTTOM

DESSOUS

"

0

†

´

évacuation de Type B-1 1 po (1 inch).

MINIMUM INCHES CLEARANCE TO COMBUSTIBLE CONSTRUCTION

DOWNFLOW POSITIONS:

Installation on non-combusibible floors only.

†

For Installation on combustible flooring only when installed on special base, Part No. KGASB0201ALL,

Coil Assembly, Part No. CD5 or CK5, or Coil Casing, Part No. KCAKC.

18 inches front clearance required for alcove.

Ø

Indicates supply or return sides when furnace is in the horizontal position. Line contact only permissible

*

between lines formed by intersections of the Top and two Sides of the furnace jacket, and building joists,
studs or framing.

DÉGAGEMENT MINIMUM EN POUCES AVEC ÉLÉMENTS

DE CONSTRUCTION COMBUSTIBLES

POUR LA POSITION COURANT DESCENDANT:

Pour l´installation sur plancher non combustible seulement.

†

´

installation sur un plancher combustible seulement quand on utilise la base spéciale, pièce

Pour l

nº KGASB0201ALL, l
nº KCAKC.

Dans une alcôve, on doit maintenir un dégagement à l

Ø

La poistion indiquée concerne le côté d

*

position horizontale.

Le contact n

´

est permis qu´entre les lignes formées par les intersections du dessus et des

deux côtés de la cherrise de la fournaise et les solives, montant sous cadre de charpente.

´

ensemble serpentin, pièce nº CD5 ou CK5, ou le carter de serpentin, pièce

´

´

entrée ou de retour quand la fournaise est dans la

avant de 18 po (450mm).

327590-101 REV. C

ne change pas avec

0"

E

D

*

I

È

S

T

Ô

C

S

E

R

E

N

V

I

T

R

C

E

E

T

I

E

N

24"

MIN

Ø

Clearance in inches
Dégagement (po).

MIN

Fig. 2 -- Clearances to Combustibles

4

A04123

80

60

A04036

Fig. 3 -- Return Air Temperature

CODES AND STANDARDS

Follow all national and local codes and standards in addition
to these instructions. The installation must comply with

regulations of the serving gas supplier, local building, heating,
plumbing, and other codes. In absence of local codes, the
installation must comply with the national codes listed below and
all authorities having jurisdiction.

In the United States and Canada, follow all codes and standards
for the following:

Step 1 — Safety

S US: National Fuel Gas Code (NFGC) NFPA 54--2006/ANSI

Z223.1--2006 and the Installation Standards, Warm Air Heating
and Air Conditioning Systems ANSI/NFPA 90B

S CANADA: CSA B149.1--00 National Standard of Canada

Natural Gas and Propane Installation Code
(CAN/CSA--B149.1--05)

Step 2 — General Installation

S US: Current edition of the NFGC and the NFPA 90B. For

copies, contact the National Fire Protection Association Inc.,
Batterymarch Park,Quincy, MA 02269; (www.NFPA.org) or for
only the NFGC, contact the American Gas Association, 400 N.
Capitol Street, N.W., Washington DC 20001 (www.AGA.org.)

S CANADA: CAN/CSA--B149.1--05. For a copy, contact

Standard Sales, CSA International, 178 Rexdale Boulevard,
Etobicoke (Toronto), Ontario, M9W 1R3 Canada Step

Step 3 — Combustion and Ventilation Air

S US: Section 8.3 of the NFGC, Air for Combustion and

Ventilation

S CANADA: Part 7 of CAN/CSA--B149.1--05, Venting Systems

and Air Supply for Appliances

Step 4 — Duct Systems

S US and CANADA: Air Conditioning Contractors Association

(ACCA) Manual D, Sheet Metal and Air Conditioning
Contractors National Association (SMACNA), or American
Society of Heating, Refrigeration, and Air Conditioning
Engineers (ASHRAE) 2001 Fundamentals Handbook Chapter
34 or 2000 HVAC Systems and Equipment Handbook Chapters
9 and 16.

Step 5 — Acoustical Lining and Fibrous Glass Duct

S US and CANADA: current edition of SMACNA and NFPA

90B as tested by UL Standard 181 for Class I Rigid Air Ducts

Step 6 — Gas Piping and Gas Pipe Pressure Testing

S US: NFGC; chapters 5, 6, and 7 and National Plumbing Codes
S CANADA: CAN/CSA--B149.1--05 Parts 4, 5, 6 and 9 and

Appendices A, B, E and H.

Step 7 — Electrical Connections

S US: National Electrical Code (NEC) ANSI/NFPA 70--2006
S CANADA: Canadian Electrical Code CSA C22.1

Step 8 — Venting

S US: NFGC; chapters 12 and 13
S CANADA: CAN/CSA--B149.1--05 Part 8 and Appendix C

ELECTROSTATIC DISCHARGE (ESD)

PRECAUTIONS PROCEDURE

!

CAUTION

FURNACE RELIABILITY HAZARD

Improper installation or service of furnace may cause
premature furnace component failure.

Electrostatic discharge can affect electronic components.
Follow the Electrostatic Discharge Precautions Procedure
listed below during furnace installation and servicing to
protect the furnace electronic control. Precautions will
prevent electrostatic discharges from personnel and hand
tools which are held during the procedure. These
precautions will help to avoid exposing the control to
electrostatic discharge by putting the furnace, the control,
and the person at the same electrostatic potential.

1. Disconnect all power to the furnace. Multiple disconnects
may be required. DO NOT TOUCH THE CONTROL OR
ANY WIRE CONNECTED TO THE CONTROL PRIOR
TO DISCHARGING YOUR BODY’S
ELECTROSTATIC CHARGE TO GROUND.

2. Firmly touch the clean, unpainted, metal surface of the
furnace chassis which is close to the control. Tools held in
a person’s hand during grounding will be satisfactorily
discharged.

3. After touching the chassis, you may proceed to service the
control or connecting wires as long as you do nothing to
recharge your body with static electricity (for example;
DO NOT move or shuffle your feet, do not touch
ungrounded objects, etc.).

4. If you touch ungrounded objects (and recharge your body
with static electricity), firmly touch a clean, unpainted
metal surface of the furnace again before touching control
or wires.

5. Use this procedure for installed and uninstalled
(ungrounded) furnaces.

6. Before removing a new control from its container,
discharge your body’s electrostatic charge to ground to
protect the control from damage. If the control is to be
installed in a furnace, follow items 1 through 4 before
bringing the control or yourself in contact with the
furnace. Put all used and new controls into containers
before touching ungrounded objects.

7. An ESD service kit (available from commercial sources)
mayalsobeusedtopreventESDdamage.

312A

5

THE BLOWER IS LOCATED

TO THE RIGHT OF THE

BURNER SECTION, AND

AIR CONDITIONED AIR IS

DISCHARGED TO THE LEFT.

THE BLOWER IS

LOCATED BELOW THE

BURNER SECTION, AND

CONDITIONED AIR IS

DISCHARGED UPWARD.

THE BLOWER IS

LOCATED ABOVE THE

312A

BURNER SECTION, AND

CONDITIONED AIR IS

DISCHARGED DOWNWARD

LOCATION

GENERAL

This multipoise furnace is shipped in packaged configuration.
Some assembly and modifications are required when used in any
of the four applications shown in Fig. 4.

NOTE: For high--altitude installations, the high--altitude
conversion kit MUST be installed at or above 5500 ft above sea
level. Obtain high--altitude conversion kit from your area
authorized distributor.

This furnace must:
S be installed so the electrical components are protected from

water.

S not be installed directly on any combustible material other than

wood flooring (refer to SAFETY CONSIDERATIONS).

S be located close to the chimney or vent and attached to an air

distribution system. Refer to Air Ducts section.

S be provided ample space for servicing and cleaning. Always

comply with minimum fire protection clearances shown on the
furnace clearance to combustible construction label.

!

WARNING

CARBON MONOXIDE POISONING AND UNIT
DAMAGE HAZARD

Failure to follow this warning could result in personal
injury or death, and furnace damage.

Corrosive or contaminated air may cause failure of parts
containing flue gas, which could leak into the living space.
Air for combustion must not be contaminated by halogen
compounds, which include fluoride, chloride, bromide, and
iodide. These elements can corrode heat exchangers and
shorten furnace life. Air contaminants are found in aerosol
sprays, detergents, bleaches, cleaning solvents, salts, air
fresheners, and other household products. Do not install
furnace in a corrosive or contaminated atmosphere. Make
sure all combustion and circulating air requirements are met,
in addition to all local codes and ordinances.

THE BLOWER IS

LOCATED TO THE LEFT

OF THE BURNER SECTION,

AND CONDITIONED AIR IS

DISCHARGED TO THE RIGHT.

A02097

Fig. 4 -- Multipoise Orientations

The following types of furnace installations may require
OUTDOOR AIR for combustion due to chemical exposures:

S Commercial buildings
S Buildings with indoor pools
S Laundry rooms
S Hobby or craft rooms, and
S Chemical storage areas

If air is exposed to the following substances, it should not be used
for combustion air, and outdoor air may be required for

combustion:

S Permanent wave solutions
S Chlorinated waxes and cleaners
S Chlorine based swimming pool chemicals
S Water softening chemicals
S De-- icing salts or chemicals
S Carbon tetrachloride
S Halogen type refrigerants
S Cleaning solvents (such as perchloroethylene)
S Printing inks, paint removers, varnishes, etc.
S Hydrochloric acid
S Cements and glues
S Antistatic fabric softeners for clothes dryers

S Masonry acid washing materials

All fuel--burning equipment must be supplied with air for fuel
combustion. Sufficient air must be provided to avoid negative
pressure in the equipment room or space. A positive seal mu st be
made between the furnace cabinet and the return--air duct to
prevent pulling air from the burner area and from draft safeguard
opening.

6

!

WARNING

FIRE, INJURY OR DEATH HAZARD

Failure to follow this warning could result in personal
injury, death, and/or property damage.

When the furnace is installed in a residential garage, the
burners and ignition sources must be located at least 18
inches above the floor. The furnace must be located or
protected to avoid damage by vehicles. When the furnace is
installed in a public garage, airplane hangar, or other
building having a hazardous atmosphere, the furnace must
be installed in accordance with the NFGC or
CAN/CSA--B149.1--05. (See Fig. 5.)

Fig. 6 -- Prohibit Installation on Back

!

CAUTION

A02054

18-IN. MINIMUM

TO BURNERS

A93044

Fig. 5 -- Installation in a Garage

!

WARNING

FIRE HAZARD

Failure to follow this warning could result in personal
injury, death and/or property damage.

Do not install the furnace on its back or hang furnace with
control compartment facing downward. Safety control
operation will be adversely affected. Never connect
return-- air ducts to the back of the furnace. (See Fig. 6.)

PROPERTY DAMAGE HAZARD

Improper use or installation of this furnace may cause
premature component failure. This gas furnace may be used
for construction heat provided that:

--The furnace is permanently installed with all electrical
wiring, piping, venting and ducting installed according to
these installation instructions. A return air duct is provided,
sealed to the furnace casing, and terminated outside the
space containing the furnace. This prevents a negative
pressure condition as created by the circulating air blower,
causing a flame roll--out and/or drawing combustion
products into the structure.

--The furnace is controlled by a thermostat. It may not be
”hot wired” to provide heat continuously to the structure
without thermostatic control.

--Clean outside air is provided for combustion. This is to
minimize the corrosive effects of adhesives, sealers and
other construction materials. It also prevents the
entrainment of drywall dust into combustion air, which can
cause fouling and plugging of furnace components.

--The temperature of the return air to the furnace is
maintained between 55_F(13_C) and 80_F(27_C), with
no evening setback or shutdown. The use of the furnace
while the structure is under construction is deemed to be
intermittent operation per our installation instructions.

--The air temperature rise is within the rated rise range on
the furnace rating plate, and the gas input rate has been set
to the nameplate value.

--The filters used to clean the circulating air during the
construction process must be either changed or thoroughly
cleaned prior to occupancy.

--The furnace, ductwork and filters are cleaned as necessary
to remove drywall dust and construction debris from all
HVAC system components after construction is completed.

--Verify proper furnace operating conditions including
ignition, gas input rate, air temperature rise, and venting
according to these installation instructions.

312A

LOCATION RELATIVE TO COOLING EQUIPMENT

The cooling coil must be installed parallel with, or on the
downstream side of the unit to avoid condensation in the heat
exchangers. When installed parallel with the furnace, dampers or
other flow control must prevent chilled air from entering the
furnace. If the dampers are manually operated, they must be

7

equipped with means to prevent operation of either unit unless
the damper is in the full--heat or full--cool position.

AIR FOR COMBUSTION AND

VENTILATION

Provisions for adequate combustion, ventilation, and dilution air
must be provided in accordance with:

U.S. installations: Section 8.3 of the NFGC, Air for Combustion
and Ventilation, and applicable provisions of the local building
codes.

Canadian installations: Part 8 of the CAN/CSA--B149.1--05,
Venting Systems and Air Supply for Appliances and all
authorities having jurisdiction.

!

CAUTION

FURNACE CORROSION HAZARD

Failure to follow this caution may result in furnace damage.

312A

Air for combustion must not be contaminated by halogen
compounds, which include fluoride, chloride, bromide, and
iodide. These elements can corrode heat exchangers and
shorten furnace life. Air contaminants are found in aerosol
sprays, detergents, bleaches, cleaning solvents, salts, air
fresheners, and other household products.

!

WARNING

CARBON MONOXIDE POISONING HAZARD

Failure to follow this warning could result in personal
injury or death.

The operation of exhaust fans, kitchen ventilation fans,
clothes dryers, attic exhaust fans or fireplaces could create a
NEGATIVE PRESSURE CONDITION at the furnace.
Make--up air MUST be provided for the ventilation devices,
in addition to that required by the furnace. Refer to Carbon
Monoxide Poisoning Hazard warning in venting section of
these instructions to determine if an adequate amount of
make--up air is available.

The requirements for combustion and ventilation air depend upon
whether or not the furnace is located in a space having a volume
of at least 50 cubic feet per 1,000 Btuh input rating for all gas
appliances installed in the space.

S Spaces having less than 50 cubic feet per 1,000 Btuh require the

Outdoor Combustion Air Method.

S Spaces having at least 50 cubic feet per 1,000 Btuh may use the

Indoor Combustion Air, Standard or Known Air Infiltration
Method.

Outdoor Combustion Air

1. Provide the space with sufficient air for proper
combustion, ventilation, and dilution of flue gases using
permanent horihorizontal or vertical duct(s) or opening(s)
directly communicating with the outdoors or spaces that
freely communicate with the outdoors.

2. Fig. 7 illustrates how to provide TWO OUTDOOR
OPENINGS, one inlet and one outlet combustion and
ventilation air opening, to the outdoors.

a. One opening MUST commence within 12 in. (300 mm)

of the ceiling and the second opening MUST commence
within 12 in. (300 mm) of the floor.

b. Size openings and ducts per Fig. 7 and Table 2.

c. TWO HORIZONTAL DUCTS require 1 square inch of

free area per 2,000 Btuh (1,100 mm2/kW) of combined
input for all gas appliances in the space per Fig. 7 and
Tab le 2.

d. TWO OPENINGS OR VERTICAL DUCTS require 1

square inch of free area per 4,000 Btuh (550 mm2/kW)
for combined input of all gas appliances in the space per
Fig. 7 and Table 2.

3. ONE OUTDOOR OPENING requires:

a. 1 square inch offreearea per 3,000 Btuh (734 mm2/kW)

for combined input of all gas appliances in the space per
Tab le 2 a nd

b. Not less than the sum of the areas of all vent connectors

in the space.

Method

Table 2 – Minimum Free Area Required for Each Combustion Air Opening or Duct to Outdoors

TWO HORIZONTAL DUCTS SINGLE DUCT OR OPENING

FURNACE

INPUT

(BTUH)

44,000 22 6 14.7 5 11 4
66,000 33 7 22 6 16.5 5

88,000 44 8 29.3 7 22 6
110,000 55 9 36.7 7 27.5 6
132,000 66 10 44 8 33 7
154,000 77 10 51.3 9 38.5 8

FURNACE WATER HEATER TOTAL INPUT

110,000 + 30,000 = (140,000 divided by 4,000) = 35.0 Sq. In. for each two Vertical Ducts or Openings

66,000 + 40,000 = (106,000 divided by 3,000) = 35.3 Sq. In. for a Single Duct or Opening
88,000 + 30,000 = (118,000 divided by 2,000) = 59.0 Sq. In. for each of two Horizontal Ducts

(1 SQ. IN./2,000 BTUH)

(1,100 SQ. MM/KW)

Free Area of

Opening and Duct

(Sq. In.)

Round Duct

(in. Dia)

(1 SQ. IN./3,000 BTUH)

(734 SQ. MM/KW)

Free Area of

Opening and Duct

(sq. In.)

8

Round Duct

(in. Dia)

TWO OPENINGS OR VERTICAL

Free Area of

Opening and Duct

(Sq. In.)

DUCTS

(1 SQ. IN./4,000 BTUH)

(550 SQ. MM/KW)

Round Duct

(In. Dia)

DUCTS

*

OUTDOORS

TO

1 SQ IN.
PER 4000
BTUH*

CIRCULATING AIR

DUCTS

VENT THROUGH ROOF

12″ MAX

1 SQ IN.
PER 2000
BTUH*

DUCTS

TO

OUTDOORS

1 SQ IN.
PER 2000
BTUH*

12″ MAX

CIRCULATING AIR DUCTS

Minimum dimensions of 3 in.

Use any of the following

NOTE:

combinations of openings:
A & B C & D D & E F & G

B

A

AIR DUCTS

CIRCULATING

OPENINGS SHALL BE

OF COMBUSTION AIR

CLEARANCE IN FRONT

D

VENT
THROUGH
ROOF

AT LEAST 3 IN.

OUTDOORS

C

DUCT

TO

E

12″ MAX

F

G

1 SQ IN.
PER 4000
BTUH*

Fig. 7 -- Air for Combustion, Ventilation and Dilution for

Outdoors

12″
MAX

1 SQ IN.

PER
4000

BTUH*

OUTDOORS

1 SQ IN.

PER

4000

BTUH*

12″
MAX

A03174

12" MAX

1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL

INTERIOR

HEATED

SPACE

CIRCULATING AIR DUCTS

* Minimum opening size is 100 sq in. with
minimum dimensions of 3 in.

†

Minimum of 3 in. . when type-B1 vent is used.

UNCONFINED
SPACE

6" MIN
(FRONT)

1 SQ IN.
PER 1000
BTUH* IN DOOR

OPENINGS SHALL BE AT LEAST 3 IN.

OR WALL

CLEARANCE IN FRONT OF COMBUSTION AIR

†

12" MAX

A03175

Fig. 8 -- Air for Combustion, Ventilation, and Dilution from

Indoors

312A

The opening shall commence within 12 in. (300 mm) of the
ceiling. Appliances in the space shall have clearances of at least 1
in. (25 mm) from the sides and back and 6 in. (150 mm) from the
front. The opening shall directly communicate with the outdoors
or shall communicate through a vertical or horizontal duct to the
outdoors or spaces (crawl or attic) that freely communicate with
the outdoors.

Indoor Combustion Air
Known --Air--Infiltration Rate

E NFPA & AGA Standard and

Methods

Indoor air is permitted for combustion, ventilation, and dilution,
if the Standard or Known--Air--Infiltration Method is used.

!

WARNING

CARBON MONOXIDE POISONING HAZARD

Failure to follow this warning could result in death and/or
personal injury.

Many homes require air to be supplied from outdoors for
furnace combustion, ventilation, and dilution of flue gases.
The furnace combustion air supply must be provided in
accordance with this instruction manual.

The Standard Method:

1. The space has no less volume than 50 cubic feet per 1,000
Btuh of the maximum input ratings for all gas appliances
installed in the space and

2. The air infiltration rate is not known to be less than 0.40
air changes per hour (ACH).

The Known Air Infiltration Rate Method shall be used, if the
infiltration rate is known to be:

1. Less than 0.40 ACH and

2. Equal to or greater than 0.10 ACH

Infiltration rates greater than 0.60 ACH shall not be used. The
minimum required volume of the space varies with the number of
ACH and shall be determined per Table 3 or Equations 1 and 2.
Determine the minimum required volume for each appliance in
the space and add the volumes together to get the total minimum
required volume for the space.

9

Table 3 – Minimum Space Volumes for 100% Combustion, Ventilation, and Dilution from Indoors

OTHER THAN FAN--- ASSISTED TOTAL

ACH

0.60 1,050 1,400 1,750 1,100 1,650 2,200 2,750 3,300 3,850

0.50 1,260 1,680 2,100 1,320 1,980 2,640 3,300 3,960 4,620

0.40 1,575 2,100 2,625 1,650 2,475 3,300 4,125 4,950 5,775

0.30 2,100 2,800 3,500 2,200 3,300 4,400 5,500 6,600 7,700

0.20 3,150 4,200 5,250 3,300 4,950 6,600 8,250 9,900 11,550

0.10 6,300 8,400 10,500 6,600 9,900 13,200 16,500 19,800 23,100

0.00 NP NP NP NP NP NP NP NP NP

NP = Not Permitted

Table 3--Minimum Space Volumes were determined by using
the following equations from the National Fuel Gas Code ANSI

Z223.1--2006/NFPA 54--2006, 9.3.2.2:

1. For other than fan-- assisted appliances, such as a draft
hood--equipped water heater:

312A

Volume

2. For fan--assisted applicances such as this furnace:

Volume

If:

= combined input of all other than fan--assisted

I

other

= combined input of all fan--assisted appliances in

I

fan

ACH = air changes per hour (ACH shall not exceed 0.60.)

The following requirements apply to the Standard Method and
to the Known Air Infiltration Rate Method.

1. Adjoining rooms can be considered part of a space if:

a. There are no closable doors between rooms.

b. Combining spaces on same floor level. Each opening

shall have free area of at least 1 in.2/1,000 Btuh (2,000
mm2/kW) of the total input rating of all gas appliances
in the space, but not less than 100 in.2 (0.06 m2). One
opening shall commence within 12 in. (300 mm) of the
ceiling and the second opening shall commence within
12 in. (300 mm) of the floor. The minimum dimension
of air openings shall be at least 3 in. (80 mm). (See Fig.

8.)

c. Combining space on different floor levels. The volumes

of spaces on different floor levels shall be considered as
communicating spaces if connected by one or more
permanent openings in doors or floors having free area
of at least 2 in.2/1,000 Btuh (4,400 mm2/kW) of total
input rating of all gas appliances.

2. An attic or crawlspace may be considered a space that
freely communicates with the outdoors provided there are
adequate permanent ventilation openings directly to
outdoors having free area of at least 1--in.2/4,000 Btuh of
total input rating for all gas appliances in the space.

3. In spaces that use the Indoor Combustion Air Method,
infiltration should be adequate to provide air for
combustion, permanent ventilation and dilution of flue
gases. However, in buildings with unusually tight

(1,000s BTUH GAS INPUT RATE)

30 40 50 44 66 88 110 132 154

SpaceVolume(ft3)

21ft

=

Other

Fan

appliances in Btuh/hr

Btuh/hr

=

ACH

15ft
ACH

3

3

I

other

1000 Btu/hr

I

fan

1000 Btu/hr

A04002

A04003

Combination of Indoor and Outdoor

1. Indoor openings shall compy with the Indoor

2. Outdoor openings shall be located as required in the

3. Outdoor openings shall be sized as follows:

UPFLOW INSTALLATION

Bottom Return Air

These furnaces are shipped with bottom closure panel installed in
bottom return--air opening. Remove and discard this panel when
bottom return air is used. To remove bottom closure panel,
perform the following:

1. Tilt or raise furnace and remove 2 screws holding bottom

2. Rotate bottom filler panel downward to release holding

3. Remove bottom closure panel.

4. Reinstall bottom filler panel and screws.

Side Return Air

These furnaces are shipped with bottom closure panel installed in
bottom return--air opening. This panel MUST be in place when
only side return air is used.

NOTE: Side return--air openings can be used in UPFLOW and
most HORIZONTAL configurations. Do not use side return--air
openings in DOWNFLOW configuration.

FAN--- ASSISTED TOTAL

(1,000s BTUH GAS INPUT RATE)

construction, additional air MUST be provided using the
methods described in the Outdoor Combustion Air
Method section. Unusually tight construction is defined as
Construction with:

a. Walls and ceilings exposed to the outdoors have a

continuous, sealed vapor barrier. Openings are gasketed
or sealed and

b. Doors and openable windows are weatherstripped and

c. Other openings are caulked or sealed. These include

joints around window and door frames, between sole
plates and floors, between wall-- ceiling joints, between
wall panels, at penetrations for plumbing, electrical and
gas lines, etc.

Air

Combustion Air Method below and,

Outdoor Combustion Air Method mentioned previously

and,

a. Calculate the Ratio of all Indoor Space volume divided

by required volume for Indoor Combustion Air
Method below.

b. Outdoor opening size reduction Factor is 1 minus the

Ratio in a. above.

c. Minimum size of Outdoor openings shall be the size

required in Outdoor Combustion Air Method above
multiplied by reduction Factor in b. above. The
minimumdimension of air openingsshallbenot lessthan
3in.(80mm).

INSTALLATION

Inlet

filler panel. (See Fig. 9.)

tabs.

Inlet

10

A02098

Fig. 9 -- Removing Bottom Closure Panel

Leveling Legs (If Desir

ed)

In upflow position with side return inlet(s), leveling legs may be
used. (See Fig. 10.) Install field--supplied, 5/16 X 1--1/2 in. (max)
corrosion --resistant machine bolts, washers and nuts.

NOTE: Bottom closure must be used when leveling legs are
used. It may be necessary to remove and reinstall bottom closure
panel to install leveling legs. To remove bottom closure panel, see
item 1 in Bottom Return Air Inlet section in Step 1 above.

To install leveling legs:

1. Position furnace on its back. Locate and drill a hole in
each bottom corner of furnace. (See Fig. 10.)

2. For each leg, install nut on bolt and then install bolt and
nut in hole. (Install flat washer if desired.)

3. Install another nut on other side of furnace base. (Install
flat washer if desired.)

4. Adjust outside nut to provide desired height, and tighten
inside nut to secure arrangement.

5. Reinstall bottom closure panel if removed.

5

⁄16″

5

⁄16″

1 3⁄4″

3

⁄4″

1

5

⁄16″

5

⁄16″

3

1

⁄4″

3

1

⁄4″

A02071

Fig. 10 -- Leveling Legs

DOWNFLOW INSTALLA

TION

NOTE: For downflow applications, this furnace is approved for

use on combustible flooring when any one of the following 3
accessories are used:

S Special Base, KGASB
S Cased Coil Assembly Part No. CD5 or CK5
S Coil Box Part No. KCAKC

1. Determine application being installed from Table 4.

2. Construct hole in floor per Table 4 and Fig. 11.

3. Construct plenum to dimensions specified in Table 4 and
Fig. 11.

4. If downflow subbase, KGASB is used, install as shown in
Fig. 12. If Coil Assembly Part No. CD5 or CK5 or Coil
Box Part No. KCAKC is used, install as shown in Fig. 13.

NOTE: It is recommended that the perforated supply--air duct
flanges be completely folded over or removed from furnace when
installing the furnace on a factory --supplied cased coil or coil box.
To remove the supply--air duct flange, use wide duct pliers or
hand seamers to bend flange back and forth until it breaks off. Be
careful of sharp edges. (See Fig. 14.)

Bottom Return Air

Inlet

These furnaces are shipped with bottom closure panel installed in
bottom return--air opening. Remove and discard this panel when
bottom return air is used. To remove bottom closure panel,
perform the following:

1. Tilt or raise furnace and remove 2 screws holding bottom
filler panel. (See Fig. 9.)

2. Rotate bottom filler panel downward to release holding
tabs.

3. Remove bottom closure panel.

4. Reinstall bottom filler panel and screws.

HORIZONTAL INSTALLA

TION

The furnace can be installed horizontally in an attic or crawl space
on either the left--hand (LH) or right--hand (RH) side. The furnace
can be hung from floor joists, rafters or trusses or installed on a
non--combustible platform, blocks, bricks or pad.

!

WARNING

FIRE, EXPLOSION, AND CARBON MONOXIDE
POISONING HAZARD

Failure to follow this warning could result in personal
injury, death, or property damage.

Do not install the furnace on its back or hang furnace with
control compartment facing downward. Safety control
operation will be adversely affected. Never connect
return-- air ducts to the back of the furnace.

Suspended Furnace Support

The furnace may be supported under each end with threaded rod,
angle iron or metal plumber’s strap as shown. (See Fig. 15 and

16.) Secure angle iron to bottom of furnace as shown.
Heavy--gauge sheet metal straps (plumber’s straps) may be used
to suspend the furnace from each bottom corner. To prevent
screws from pulling out, use 2 #8 x .--in. screw into the side and 2
#8 x .--in. screw in the bottom of the furnace casing for each strap.
(See Fig. 15 and 16.)

If the screws are attached to ONLY the furnace sides and not the
bottom, the straps must be vertical against the furnace sides and
not pull away from the furnace sides, so that the strap attachment
screws are not in tension (are loaded in shear) for reliable support.

Platform Furnace

Support

Construct working platform at location where all required furnace
clearances are met. (See Fig. 2 and 17.) For furnaces with 1--in.
clearance requirement on side, set furnace on non--combustible
blocks, bricks or angle iron. For crawlspace installations, if the
furnace is not suspended from the floor joists, the ground

312A

11

underneath furnace must be level and the furnace set on blocks or
bricks.

Roll--Out Pr

otection

Provide a minimum 17--3/4 in. X 22 in. piece of sheet metal for
flame roll--out protection in front of burner area for furnaces
closer than 12 inches above the combustible deck or suspended
furnaces closer than 12 inches to joists. The sheet metal MUST
extend underneath the furnace casing by 1 in. with the door
removed.

The bottom closure panel on furnaces of widths 17--1/2 in. and
larger may be used for flame roll--out protection when bottom of
furnace is used for return air connection. See Fig. 17 for proper
orientation of roll--out shield.

Bottom Return Air

Inlet

These furnaces are shipped with bottom closure panel installed in
bottom return--air opening. Remove and discard this panel when
bottom return air is used. To remove bottom closure panel,
perform the following:

312A

1. Tilt or raise furnace and remove 2 screws holding bottom
filler panel. (See Fig. 9.)

2. Rotate bottom filler panel downward to release holding
tabs.

3. Remove bottom closure panel.

4. Reinstall bottom filler panel and screws.

Side Return Air

Inlet

These furnaces are shipped with bottom closure panel installed in
bottom return--air opening. This panel MUST be in place when
side return air inlet(s) are used without a bottom return air inlet.

FURNACE

(OR COIL CASING

WHEN USED)

COMBUSTIBLE

FLOORING

DOWNFLOW

SUBBASE

SHEET METAL

PLENUM

FLOOR

OPENING

A096285

Fig. 12 -- Furnace, Plenum, and Subbase installed on a

Combustible Floor

A

PLENUM

OPENING

B

OPENING

D

FLOOR

C

Fig. 11 -- Floor and Plenum Opening Dimensions

A096283

FURNACE

CD5 OR CK5

COIL ASSEMBLY

OR KCAKC

COIL BOX

COMBUSTIBLE

FLOORING

SHEET METAL

PLENUM

FLOOR

OPENING

A04140

A04140

Fig. 13 -- Furnace, Plenum, and Coil Assembly or Coil Box

Installed on a Combustible Floor

12

FURNACE

D

CASING

WIDTH

14–3/16

17–1/2

21

24--- 1/2

Table 4 – Opening dimensions (In.)

APPLICATION

Upflow Applications on Combustible or Noncombustible

Flooring (KGASB subbase not required)

Downflow Applications on Noncombustible Flooring (KGASB

subbase not required)

Downflow applications on combustible flooring

(KGASB subbase required)

Downflow Applications on Combustible Flooring with CD5 or

CK5 Coil Assembly or KCAKC coil box

(KGASB subbase not required)

Upflow Applications on Combustible or Noncombustible

Flooring (KGASB subbase not required)

Downflow Applications on Noncombustible Flooring

(KGASB subbase not required)

Downflow applications on combustible flooring

(KGASB subbase required)

Downflow Applications on Combustible Flooring with CD5 or

CK5 Coil Assembly or KCAKC coil box

(KGASB subbase not required)

Upflow Applications on Combustible or Noncombustible

Flooring (KGASB subbase not required)

Downflow Applications on Noncombustible Flooring

(KGASB subbase not required)

Downflow applications on combustible flooring

(KGASB subbase required)

Downflow Applications on Combustible Flooring with CD5 or

CK5 Coil Assembly or KCAKC coil box

(KGASB subbase not required)

Upflow Applications on Combustible or Noncombustible

Flooring (KGASB subbase not required)

Downflow Applications on Noncombustible Flooring

(KGASB subbase not required)

Downflow applications on Combustible flooring

(KGASB subbase required)

Downflow Applications on Combustible Flooring with CD5 or

CK5 Coil Assembly or KCAKC coil box

(KGASB subbase not required)

PLENUM OPENING FLOOR OPENING

A B C D

12--- 11/16 21--- 5/8 13---5/16 22--- 1/4

12--- 9/16 19 13--- 3/16 19--- 5/8

11--- 13/16 19 13 --- 7/16 20 ---5/8

12--- 5/16 19 13--- 5/16 20

16 21--- 5/8 16 ---5/8 22---1/4

15--- 7/8 19 16---1/2 19 --- 5/8

15--- 1/8 19 16---3/4 20 --- 5/8

15--- 1/2 19 16---1/2 20

19--- 1/2 21 --- 5/8 20--- 1/8 22 --- 1/4

19--- 3/8 19 20 19--- 5/8

18--- 5/8 19 20---1/4 20 --- 5/8

19 19 20 20

23 21--- 1/8 23 ---5/8 22---1/4

22--- 7/8 19 23---1/2 19 --- 5/8

22--- 1/8 19 23---3/4 20 --- 5/8

22--- 1/2 19 23---1/2 20

312A

UPFLO

90û

120û

MIN

W OWNFLOW

YES

YES

NOT
RECOMMENDED

D

120û
MIN

Fig. 14 -- Duct Flanges

YES

YES

NOT
RECOMMENDED

13

HORIZONTAL

90û

120û

MIN

YES

YES

NOT
RECOMMENDE

A02329

OUTER DOOR
ASSEMBLY

1

/4

" THREADED ROD

4 REQ.

312A

8" MIN FOR DOOR
REMOVAL

(2) HEX NUTS, (2) WASHERS & (2) LOCK WASHERS
REQ. PER ROD

Fig. 15 -- Horizontal Unit Suspension

SECURE ANGLE
IRON TO BOTTOM
OF FURNACE WITH
3 #8 x
TYPICAL FOR 2 SUPPORTS

1

1

/4

1" SQUARE, 1
OR UNI-STRUT MAY BE USED

" x 1

1

/4

" x

/4

" ANGLE IRON

3

/4

" SCREWS

METHOD 2
USE (42) #8 x 3/4 SHEET
METAL SCREWS TYPICAL
FOR EACH STRAPS.THE
STRAPS SHOULD BE
VERTICAL AGAINST THE
FURNACE SIDES AND NOT
PULL AWAY FROM THE
FURNACE SIDES.

A02345

METHOD 1
FOLD ALL STRAPS UNDER
FURNACE AND SECURE WTH
(42) #8 x 3/4 SHEET METAL SCREWS
(2 SCREWS IN SIDE AND 2 SCREWS
IN BOTTOM).

Fig. 16 -- Horizontal Suspension with Straps

14

A03176

LINE CONTACT ONLY PERMISSIBLE BETWEEN
LINES FORMED BY INTERSECTIONS OF
THE TOP AND TWO SIDES OF THE FURNACE
JACKET AND BUILDING JOISTS,
STUDS, OR FRAMING.

GAS
ENTRY

TYPE-B
VENT

17 3/4

″ OVER ALL

4 3/4

″ UNDER DOOR

1″ UNDER FURNACE

EXTEND OUT 12″ OUT
FROM FACE OF DOOR

17 3/4

22

EQUIPMENT MANUAL

SHUT-OFF GAS VALVE

SEDIMENT

TRAP

UNION

SHEET
METAL

Fig. 17 -- Typical Attic Installation

Not all horizontal furnaces are approved for side return air
connections. (See Fig. 20.)

FILTER

ARRANGEMENT

!

WARNING

CARBON MONOXIDE POISONING HAZARD

Failure to follow this warning could result in personal
injury, or death.

Never operate a furnace without a filter or with filter access
door removed.

There are no provisions for an internal filter rack in these
furnaces. An external filter rack is required.

This furnace is shipped with a factory--supplied Media Filter
Cabinet. The Media Filter Cabinet uses either a factory--supplied
standard 1--inch filter or 4--inch wide Media Filter which can be
purchased separately.

Refer to the instructions supplied with Media Cabinet for
assembly and installation options.

DUCTS

AIR

General Requir

ements

The duct system should be designed and sized according to
accepted national standards such as those published by: Air
Conditioning Contractors Association (ACCA), Sheet Metal and
Air Conditioning Contractors National Association (SMACNA)
or American Society of Heating, Refrigerating and Air
Conditioning Engineers (ASHRAE) or consult The Air Systems
Design Guidelines reference tables available from your local
distributor. The duct system should be sized to handle the
required system design CFM at the design external static pressure.
The furnace airflow rates are provided in Table 5--Air Delivery
CFM (With Filter).

When a furnace is installed so that the supply ducts carry air
circulated by the furnace to areas outside the space containing the
furnace, the return air shall also be handled by duct(s) sealed to
the furnace casing and terminating outside the space containing
the furnace.

6″ MIN*

″

″

30-IN. MIN
WORK AREA

* WHEN USED WITH
SINGLE WALL VENT
CONNECTIONS

312A

A03177

Secure ductwork with proper fasteners for type of ductwork used.
Seal supply-- and return--duct connections to furnace with code
approved tape or duct sealer.

NOTE: Flexible connections should be used between ductwork
and furnace to prevent transmission of vibration.

Ductwork passing through unconditioned space should be
insulated to enhance system performance. When air conditioning
is used, a vapor barrier is recommended.

Maintain a 1--in. clearance from combustible materials to supply
air ductwork for a distance of 36 in. horizontally from the
furnace. See NFPA 90B or local code for further requirements.

Ductwork Acoustical Tr
NOTE: Metal duct systems that do not have a 90_ elbow and 10

ft of main duct to the first branch take--off may require internal
acoustical lining. As an alternative, fibrous ductwork may be used
if constructed and installed in accordance with the latest edition of
SMACNA construction standard on fibrous glass ducts. Both
acoustical lining and fibrous ductwork shall comply with NFPA
90B as tested by UL Standard 181 for Class 1 Rigid air ducts.

Supply Air

Connections

For a furnace not equipped with a cooling coil, the outlet duct
shall be provided with a removable access panel. This opening
shall be accessible when the furnace is installed and shall be of
such a size that the heat exchanger can be viewed for possible
openings using light assistance or a probe can be inserted for
sampling the air stream. The cover attachment shall prevent leaks.

Upflow and Horizontal

Connect supply--air duct to flanges on furnace supply--air outlet.
Bend flange upward to 90_ with wide duct pliers. (See Fig. 14.)
The supply--air duct must be connected to ONLY the furnace
supply--outlet--air duct flanges or air conditioning coil casing
(when used). DO NOT cut main furnace casing side to attach
supply air duct, humidifier, or other accessories. All accessories
MUST be connected to duct external to furnace main casing.

eatment

Furnaces

15

Table 5 – Air Delivery -- CFM (With Filter)*

312A

FURNACE

SIZE

045--- 08 /

024045

045--- 12 /

036045

070--- 081 /

024070

070--- 12 /

036070

070--- 16 /

048070

090--- 14 /

042090

090--- 16 /

048090

090--- 20 /

060090

110--- 12 /

036110

110--- 16 /

048110

RETURN---AIR

INLET

Bottom or

Side(s)

Bottom or

Side(s)

Bottom or

Side(s)

Bottom or

Side(s)

Bottom or

Side(s)

Bottom or

Side(s)

Bottom or

Side(s)

Bottom Only

Both Side or 1
Side & Bottom

1Side Only

Bottom or

Side(s)

Bottom or

Side(s)

SPEED

High

M e d ---

High

M e d --- L ow

Low

High

M e d ---

High Me-

dium

M e d --- L ow

Low

High

M e d ---

High

M e d --- L ow

Low

High

M e d ---

High Me-

dium

M e d --- L ow

Low

High

M e d ---

High Me-

dium

M e d --- L ow

Low

High

M e d ---

High

M e d --- L ow

Low

High

M e d ---

High

M e d --- L ow

Low

High

M e d ---

High Me-

dium

M e d --- L ow

Low

High

M e d ---

High Me-

dium

M e d --- L ow

Low

High

M e d ---

High Me-

dium

M e d --- L ow

Low

High

M e d ---

High

M e d --- L ow

Low

High

M e d ---

High Me-

dium

M e d --- L ow

Low

EXTERNAL STATIC PRESSURE (IN. WC)

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

1120

930
820
725

1465
1295
1150
1030

860

1140

915
795
690

1440
1180
1015

885
695

1840
1610
1460
1260
1065

1650
1515
1385
1205

2060
1710
1470
1260
1030

2380
2185
1905
1595
1340

2485
2175
1845
1540
1280

2420
2160
1850
1530
1290

1625
1510
1360
1195

2055
1750
1545
1300
1050

1075

890
785
690

1400
1260
1120
1010

835

1105

885
770
665

1400
1165
1020

885
700

1790
1575
1430
1240
1040

1600
1485
1360
1180

2000
1695
1475
1365
1025

2295
2115
1865
1565
1310

2415
2130
1815
1515
1250

2345
2110
1815
1490
1250

1575
1470
1335
1180

1990
1725
1525
1290
1045

1020

850
750
655

1325
1210
1085

980
810

1055

855
740
630

1355
1150
1010

880
700

1730
1535
1400
1215
1015

1535
1440
1320
1160

1930
1665
1450
1245
1020

2205
2045
1815
1530
1280

2330
2070
1770
1475
1220

2265
2045
1765
1455
1220

1515
1415
1295
1155

1910
1670
1490
1275
1015

960
805
700
605

1250
1155
1040

945
780

1010

825
700
590

1300
1125

990
865
690

1670
1485
1360
1180

985

1465
1380
1260
1120

1835
1585
1390
1225

990

2105
1960
1740
1485
1225

2230
2000
1720
1435
1190

2165
1960
1710
1420
1190

1445
1355
1250
1115

1815
1605
1445
1235

975

895
750
650
555

1175
1090

985
895
745

955
785
655
550

1240
1085

965
845
670

1605
1435
1315
1145

955

1385
1300
1195
1065

1755
1480
1335
1165

940

2005
1875
1670
1430
1170

2135
1930
1655
1385

115

2070
1885
1635
1375

115

1355
1285
1180
1065

1695
1515
1355
1165

935

815
680
585
495

1085
1015

920
835
700

885
725
600
475

1170
1030

925
815
640

1530
1370
1260

110
915

1285
1220
1120
1005

1620
1390
1230
1090

890

1900
1770
1590
1355
1120

2030
1840
1580
1335
1105

1960
1790
1560
1320
1110

1260
1185
1100

980

1575
1400
1260
1085

880

720
600
505
405

980
930
835
765
635

815
655
510
415

1090

970
875
770
600

1450
1305
1205
1040

875

1175
1115
1025

925

1490
1245
1120

995
810

1775
1655
1490
1275
1040

1920
1740
1500
1270
1035

1850
1695
1480
1250
1040

1165
1070

985
860

1425
1255
1135
1005

815

605
500
400
305

860
830
740
685
555

715
530
420
340

1000

890
800
700
540

1370
1230
1130

985
825

1055

990
915
810

1315
1110
1005

880
720

1650
1535
1390
1160

955

1790
1620
1395
1175

945

1720
1570
1380
1160

950

990
890
810
740

1230
1120
1020

895
715

455
345
235

--- ---

725
700
620
570
445

545
420
325
245

890
785
700
605
460

1275
1145
1055

915
765

895
830
710
630

1115

955
855
750
615

1510
1400
1245
1055

850

1645
1495
1270
1045

845

1570
1445
1250
1055

835

785
725
670
605

1090

975
880
750
610

340
195

--- ---

--- ---

560
545
510
345
260

390
280

--- ---

--- ---

745
645
560
475
345

1170
1055

965
835
695

645
600
565
510

910
775
690
600
500

1335
1240
1110

920
750

1485
1345
1090

915
745

1420
1305
1110

905
740

595
530
475
410

910
785
750
620
515

16

High

M e d ---

Bottom Only

110--- 22 /

066110

*A filter is required for each return---air inlet. Airflow performance included 1---in. washable filter media such as contained in factory---authorized accessory filter
rack. To determine airflow performance without this filter, assume an additional 0.1 in. wc available external static pressure.

--- --- Indicates unstable operating conditions.

Bottom Sides or

1 Side & Bottom

1Side Only

High Me-

dium

M e d --- L ow

Low

High

M e d ---

High
High

M e d ---

High Me-

dium

M e d --- L ow

Low

2530
2225
1895
1565
1320

--- ---

2205

2485
2155
1830
1520
1275

2460
2190
1885
1555
1295

--- ---

2175

2430
2135
1830
1505
1260

2380
2135
1865
1535
1265

2415
2120

2360
2100
1810
1490
1240

2285
2075
1820
1505
1235

2330
2065

2270
2040
1780
1470
1210

2200
1995
1770
1465
1205

2235
1975

2175
1970
1730
1430
1180

2085
1910
1700
1410
1160

2125
1900

2070
1885
1665
1385
1135

1970
1805
1610
1350
1105

1995
1790

1950
1790
1595
1330
1090

1835
1695
1520
1265
1035

1860
1685

1825
1680
1505
1250
1025

1695
1565
1410
1175

950

1735
1580

1685
1560
1395
1165

930

1545
1430
1290
1050

870

1605
1460

1535
1420
1275
1055

840

312A

17

Table 5 -- Air Delivery -- CFM (With Filter)* (Cont.)

FURNACE

SIZE

135--- 16 /

048135

135--- 22 /

066135

312A

155--- 20 /

060155

*A filter is required for each return---air inlet. Airflow performance included 1---in. washable filter media such as contained in factory---authorized accessory filter
rack. To determine airflow performance without this filter, assume an additional 0.1 in. wc available external static pressure.

--- --- Indicates unstable operating conditions.

RETURN---AIR

INLET

Bottom

or

Side(s)

Bottom

Only

Bottom Sides

or

1 Side & Bottom

1SideOnly

Bottom Only

Both Sides Or 1

Side & Bottom

1SideOnly

SPEED

High
M e d --- H ig h
M e d --- L ow

Low

High
M e d --- H ig h
M e d --- L ow

Low

High
M e d --- H ig h
M e d --- L ow

Low

High
M e d --- H ig h
M e d --- L ow

Low

High
M e d --- H ig h
M e d --- L ow

Low

High
M e d --- H ig h

High
M e d --- H ig h

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

2090
1790
1545
1325
2485
2195
1880
1640

--- --­2180
1880
1640

2320
2125
1845
1640

2465
2115
1800
1570

--- --­2155

--- --­2140

2010
1755
1525
1320
2400
2150
1850
1635

--- --­2145
1850
1635

2250
2065
1825
1620

2430
2105
1790
1565

--- --­2135

--- --­2095

NOTE: For horizontal applications, the top--most flange may be
bent past 90_ to allow the evaporator coil to hang on the flange
temporarily while the remaining attachment and sealing of the

EXTERNAL STATIC PRESSURE (IN. WC)

1930
1705
1500
1295
2310
2090
1820
1615

2385
2060
1820
1615

2155
1995
1765
1580

2375
2075
1770
1550

2375
2095

2260
2040

1835
1640
1450
1265
2215
2000
1780
1585

2305
2010
1780
1585

2055
1910
1710
1540

2305
2030
1735
1525

2285
2040

2180
1975

1710
1550
1380
1210
2110
1920
1715
1530

2195
1945
1715
1530

1970
1815
1650
1485

2230
1980
1695
1495

2200
1975

2085
1890

1590
1465
1315
1150
2000
1825
1635
1465

2085
1865
1635
1465

1855
1710
1570
1410

2110
1910
1640
1445

2105
1895

1975
1810

1470
1360
1215

995
1880
1720

1540
1370

1960
1765
1540
1370

1725
1610
1475
1330

2000
1830
1570
1370

1995
1790

1865
1705

1335
1210
1005

865
1725
1565

1415
1255

1825
1660
1415
1255

1600
1490
1370
1220

1865
1725
1465
1270

1870
1685

1740
1595

horizontal furnaces are approved for side return air connections.
(See Fig. 20.)

PIPING

GAS

coil are performed.

Downflow

Connect supply--air duct to supply--air outlet on furnace. Bend
flange inward past 90_ with wide duct pliers. (See Fig. 14.) The
supply--air duct must be connected to ONLY the furnace
supplyoutlet or air conditioning coil casing (when used). When
installed on combustible material, supply--air duct must be
connected to ONLY the accessory subbase, KGASB0201ALL, or
a factory approved air conditioning coil casing. DO NOT cut
main furnace casing to attach supply side air duct, humidifier, or
other accessories. All accessories MUST be connected to duct

Furnaces

!

WARNING

FIRE OR EXPLOSION HAZARD

Failure to follow this warning could result in personal
injury, death, and/or property damage.

Never purge a gas line into a combustion chamber. 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.

external to furnace casing.

Return Air

FIRE HAZARD

Failure to follow this warning could cause personal injury,
death and/or property damage.

Never connect return--air ducts to the back of the furnace.

Connections

!

WARNING

!

WARNING

FIRE OR EXPLOSION HAZARD

Failure to follow this warning could result in personal
injury, death, and/or property damage.

Use proper length of pipe to avoid stress on gas control
manifold and a gas leak.

Follow instructions below.

1025

945
855

745
1535
1405

1290
1150

1670
1515
1290
1150

1450
1340
1240
1080

1725
1590
1345
1175

1730
1550

1605
1480

835
785
670

540
1355
1255

1160
1040

1465
1325
1160
1040

1280
1175
1100

960
1545

1425
1225
1070

1570
1400

1455
1325

Downflow Furnaces

The return--air duct must be connected to return--air opening
(bottom inlet) as shown in Fig. 1. DO NOT cut into casing sides
(left or right). Side opening is permitted for only upflow and most
horizontal furnaces. Bypass humidifier connections should be
made at ductwork or coil casing sides exterior to furnace. (See
Fig. 19.) Upflow and Horizontal Furnaces The return--air duct
must be connected to bottom, sides (left or right), or a
combination of bottom and side(s) of main furnace casing as
shown in Fig. 1. Bypass humidifier may be attached into unused
return air side of the furnace casing. (See Fig. 18 and 20.) Not all

!

WARNING

FIRE OR EXPLOSION HAZARD

Failure to protect gas valve inlet from water and debris
could result in death, personal injury and/or property
damage.

Gas valve inlet and/or inlet pipe must remain capped until
gas supply line is permanently installed to protect the valve
from moisture and debris. Also, install a sediment trap in the
gas supply piping at the inlet to the gas valve.

18

Fig. 18 -- Upflow Return Air Configurations and Restrictions

Fig. 19 -- Downflow Return Air Configurations and Restrictions

A02075

A02163

312A

Fig. 20 -- Horizontal Return Air Configurations and Restrictions

19

A02162

Gas piping must be installed in accordance with national and
local codes. Refer to current edition of NFGC in the U.S. and the
CAN/CSA--B149.1--05 in Canada.

Table 6 – Maximum Capacity of Pipe*

NOMINAL

IRON
PIPE
SIZE

(IN.)

1/2 0.622 175 120 97 82 73

3/4 0.824 360 250 200 170 151

1 1.049 680 465 375 320 285

1 --- 1 / 4 1.380 1400 950 770 660 580

1 --- 1 / 2 1.610 2100 1460 1180 990 900

* Cubic ft of natural gas per hr for gas pressures of 0.5 psig (14 --- in. wc)
or less and a pressure drop of 0.5 ---in wc (based on a 0.60 specific gravity
gas). Ref: Table 12.2 ANSI Z223 ---2006/NFPA 54---2006.

INTERNAL
DIAMETER

(IN.)

LENGTH OF PIPE (FT)

10 20 30 40 50

Installations must be made in accordance with all authorities
having jurisdiction. If possible, the gas supply line should be a
separate line running directly from meter to furnace.

312A

NOTE: In the state of Massachusetts:

1. Gas supply connections MUST be performed by a
licensed plumber or gas fitter.

2. When flexible connectors are used, the maximum length
shall not exceed 36 inches (915 mm).

3. When lever handle type manual equipment shutoff valves
are used, they shall be T--handle valves.

4. The use of copper tubing for gas piping is NOT approved
by the state of Massachusetts.

Refer to Table 6 for recommended gas pipe sizing. Risers must be
used to connect to furnace and to meter. Support all gas piping
with appropriate straps, hangers, etc. Use a minimum of 1 hanger
every 6 ft Joint compound (pipe dope) should be applied
sparingly and only to male threads of joints. Pipe dope must be
resistant to the action of propane gas.

!

WARNING

FIRE OR EXPLOSION HAZARD

Failure to follow this warning could result in personal
injury, death, and/or property damage.

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 served another gas
appliance. Black iron pipe shall be installed at the furnace
gas control valve and extend a minimum of 2 in. outside the
furnace.

!

CAUTION

test pressure DOES NOT exceed maximum 0.5 psig (14--in. wc)
stated on gas control valve. (See Fig. 54.) Some installations
require gas entry on right side of furnace (as viewed in upflow).
(See Fig. 21 and 22.)

A05028

Fig. 21 -- Right Side Gas Entry Example 1

90° Elbow

2" Nipple

Street Elbow

Gas Valve

A02327

Fig. 22 -- Right Side Gas Entry Example 2

Install a sediment trap in riser leading to furnace as shown in Fig.

23. Connect a capped nipple into lower end of tee. Capped nipple
should extend below level of furnace gas controls. Place a ground
joint union between furnace gas control valve manifold and
exterior manual equipment gas shutoff valve.

GAS
SUPPLY

MANUAL
SHUTOFF
VALV E
(REQUIRED

SEDIMENT
TRAP

UNION

FURNACE DAMAGE HAZARD

Failure to follow this caution may result in furnace damage.

Connect gas pipe to furnace using a backup wrench to
avoid damaging gas controls and burner misalignment.

An accessible manual equipment shutoff valve MUST be
installed external to furnace casing and within 6 ft of furnace. A
1/8--in. NPT plugged tapping, accessible for test gauge
connection, MUST be installed immediately upstream of gas
supply connection to furnace and downstream of manual
equipment shutoff valve.

NOTE: The furnace gas control valve inlet pressure tap
connection is suitable to use as test gauge connection providing

A02035

Fig. 23 -- Typical Gas Pipe Arrangement

A 1/8--in. NPT plugged tapping, accessible for test gauge
connection, MUST be installed immediately upstream of gas
supply connection to furnace and downstream of manual
equipment shutoff valve.

20

NOTE 2

WC Y RG

W2

COM

W/W1

NOTE 1

Y/Y2

R

G

NOTES: 1.

BLK

WHT

GND

115-VOLT FIELD-

SUPPLIED

FUSED

DISCONNECT

BLK

WHT

JUNCTION
BOX

FIVE

WIRE

THREE-WIRE

HEATING-

ONLY

CONTROL

BOX

FURNACE

24-VOLT

TERMINAL

BLOCK

Fig. 24 -- Field Wiring Diagram

Piping should be pressure and leak tested in accordance with
NFGC in the United States or CAN/CSA--B149.1--05 in Canada,
local, and national plumbing and gas codes before the furnace has
been connected. After all connections have been made, purge
lines and check for leakage at furnace prior to operating furnace.

If pressure exceeds 0.5 psig (14--in. wc), gas supply pipe must be
disconnected from furnace and capped before and during supply
pipe pressure test. If test pressure is equal to or less than 0.5 psig
(14--in. wc), turn off electric shutoff switch located on furnace gas
control valve and accessible manual equipment shutoff valve
before and during supply pipe pressure test. After all connections
have been made, purge lines and check for leakage at furnace
prior to operating furnace.

The gas supply pressure shall be within the maximum and
minimum inlet supply pressures marked on the rating plate with
the furnace burners ON and OFF.

ELECTRICAL

CONNECTIONS

FIELD 24-VOLT WIRING
FIELD 115-, 208/230-, 460-VOLT WIRING
FACTORY 24-VOLT WIRING
FACTORY 115-VOLT WIRING

1-STAGE
THERMOSTAT
TERMINALS

CONDENSING

UNIT

Connect Y/Y2-terminal as shown for proper operation.
Some thermostats require a "C" terminal connection as shown.

2.
If any of the original wire, as supplied, must be replaced, use

3.
same type or equivalent wire.

!

FIELD-SUPPLIED

FUSED DISCONNECT

208/230- OR
460-VOLT
THREE
PHASE

208/230­VOLT
SINGLE

GND

PHASE

WARNING

ELECTRICAL SHOCK AND FIRE HAZARD

Failure to follow this warning could result in personal
injury, death, or property damage.

The cabinet MUST have an uninterrupted or unbroken
ground according to NEC ANSI/NFPA 70--2006 and
Canadian Electrical Code CSA C22.1 or local codes to
minimize personal injury if an electrical fault should occur.
This may consist of electrical wire, conduit approved for
electrical ground or a listed, grounded power cord (where
permitted by local code) when installed in accordance with
existing electrical codes. Refer to the power cord
manufacturer’s ratings for proper wire gauge. Do not use
gas piping as an electrical ground.

312A

A95236

!

WARNING

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal
injury or death.

Blower access panel door switch opens 115--v power to
control. No component operation can occur. Do not bypass
or close switch with panel removed.

See Fig. 24 for field wiring diagram showing typical field 115--v
wiring. Check all factory and field electrical connections for
tightness.

Field--supplied wiring shall conform with the limitations of 63_F
(33_C) rise.

!

CAUTION

FURNACE MAY NOT OPERATE HAZARD

Failure to follow this caution may result in intermittent
furnace operation.

Furnace control must be grounded for proper operation or
else control will lock out. Control must remain grounded
through green/yellow wire routed to gas valve and manifold
bracket screw.

115 -- V WIRING

Verify that the voltage, frequency, and phase correspond to that
specified on unit rating plate. Also, check to be sure that service
provided by utility is sufficient to handle load imposed by this
equipment. Refer to rating plate or Table 7 for equipment
electrical specifications.

21

Table 7 – Electrical Data

V O LT S ---

H E R T Z ---

PHASE

1 1 5 --- 6 0 --- 1 127 104 5.3 045 --- 08/024045 7.42 49 15 14
1 1 5 --- 6 0 --- 1 127 104 7.1 045 --- 12/036045 9.67 38 15 14
1 1 5 --- 6 0 --- 1 127 104 5.2 070 --- 08/024070 7.22 51 15 14
1 1 5 --- 6 0 --- 1 127 104 7.3 070 --- 12/036070 9.90 37 15 14
1 1 5 --- 6 0 --- 1 127 104 10.1 070--- 16/048070 13.42 27 15 14
1 1 5 --- 6 0 --- 1 127 104 8.2 090 --- 14/042090 10.84 34 15 14
1 1 5 --- 6 0 --- 1 127 104 9.9 090 --- 16/048090 13.0 28 15 14
1 1 5 --- 6 0 --- 1 127 104 12.9 090--- 20/060090 16.70 34 20 12
1 1 5 --- 6 0 --- 1 127 104 8.2 110 --- 12/036110 10.76 34 15 14
1 1 5 --- 6 0 --- 1 127 104 10.1 110--- 16/048110 13.19 28 15 14
1 1 5 --- 6 0 --- 1 127 104 13.7 110--- 22/066110 17.60 32 20 12
1 1 5 --- 6 0 --- 1 127 104 10.2 135--- 16/048135 13.28 27 15 14
1 1 5 --- 6 0 --- 1 127 104 14.5 135--- 22/066135 18.61 30 20 12
1 1 5 --- 6 0 --- 1 127 104 15.0 155--- 20/060155 19.34 29 20 12

* Permissible limits of the voltage ran ge at which the unit operates satisfactorily.

312A

# Unit ampacity = 125% of lar gest operating component’s full load amps plus 100% of all other potential operating components (EAC, humidifier,

etc.) full load amps.

{ Time---delay type is recommended.
} Length shown is as measured 1 way along wire path between unit and service panel for maximum 2% voltage drop.

U.S. Installations: Make all electrical connections in accordance
with National Electrical Code (NEC) ANSI/NFPA 70--2006 and
any local codes or ordinances that might apply.

Canadian Installations: Make all electrical connections in

OPERATING VOLTAGE

RANGE

MAX* MIN.*

MAX
UNIT

AMPS

FURNACE

SIZE

UNIT

AMPACITY#

4. Fasten J--Box to casing with the two screws removed in
Step 1.

5. Route J-- Box wires within furnace away from sharp edges,
rotating parts, and hot surfaces.

MAXIMUM

WIRE

LENGTH

(ft)‡

MAXIMUM

FUSE OR
CKT BKR

AMPS†

accordance with Canadian Electrical Code CSA C22.1 or
authorities having jurisdiction.

MINIMUM

WIRE

GAUGE

!

WARNING

FIRE HAZARD

Failure to follow this warning could result in personal
injury, death, or property damage.

Do not connect aluminum wire between disconnect switch
and furnace. Use only copper wire.

Use a separate branch electrical circuit with a properly sized fuse
or circuit breaker for this furnace. See Table 7 for wire size and
fuse specifications. A readily accessible means of electrical
disconnect must be located within sight of the furnace.

NOTE: Proper polarity must be maintained for 115--v wiring. If
polarity is incorrect, control LED status indicator light will flash
rapidly and furnace will NOT operate.

J--BOX RELOCA

TION

NOTE: If factory location of J--Box is acceptable, go to next

section (ELECTRICAL CONNECTION TO J--BOX).

NOTE: On 14” wide casing models, the J--Box shall not be
relocated to other side of furnace casing when the vent pipe is
routed within the casing.

1. Remove and save two screws holding J--Box. (See Fig.

25.)

NOTE: The J--Box cover need not be removed from the J--Box
in order to move the J--Box. Do NOT remove green ground
screw inside J--Box. The ground screw is not threaded into the
casing flange and can be lifted out of the clearance hole in casing
while swinging the front edge of the J--box outboard of the
casing.

2. Cut wire tie on loop in furnace wires attached to J--Box.

3. Move J--Box to desired location.

TWO

A02099

Fig. 25 -- Relocating J--Box

ELECTRICAL CONNECTION TO

J--BOX

Field-- Supplied Electrical Box on Furnace J--Box Bracket. See
Fig. 26.

1. Remove cover from furnace J--Box.

2. Attach electrical box to furnace J--Box bracket with at least
two field--supplied screws through holes in electrical box
into holes in bracket. Use blunt--nose screws that will not
pierce wire insulation.

3. Route furnace power wires through holes in electrical box
and J--Box bracket, and make field--wire connections in
electrical box. Use best practices (NEC in U.S. and CSA
C22.1 in Canada) for wire bushings, strain relief, etc.

4. Route and secure field ground wire to green ground screw
on J--Box bracket.

5. Connect line voltage leads as shown in Fig. 24.

22

6. Reinstall cover to J--Box. Do not pinch wires between
cover and bracket.

Electrical Box on Furnace Casing Side. See Fig.

!

WARNING

FIRE OR ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal
injury, death, or property damage.

If field--supplied manual disconnect switch is to be mounted
on furnace casing side, select a location where a drill or
fastener cannot damage electrical or gas components.

Fig. 26 -- Field--Supplied Electrical Box on Furnace Casing

1. Select and remove a hole knockout in the casing where the
electrical box is to be installed.

NOTE: Check that duct on side of furnace will not interfere with
installed electrical box.

2. Remove the desired electrical box hole knockout and
position the hole in the electrical box over the hole in the
furnace casing.

3. Fasten the electrical box to casing by driving two
fieldsupplied screws from inside electrical box into casing
steel.

4. Remove and save two screws holding J--Box. (See Fig.

25.)

26.

A03221

5. Pull furnace power wires out of 1/2--inch diameter hole in
J--Box. Do not loosen wires from strain--relief wire--tie on
outside of J--Box.

6. Route furnace power wires through holes in casing and
electrical box and into electrical box.

7. Pull field power wires into electrical box.

8. Remove cover from furnace J--Box.

9. Route field ground wire through holes in electrical box
and casing, and into furnace J--Box.

10. Reattach furnace J--Box to furnace casing with screws
removedinStep4.

11. Secure field ground wire to J--Box green ground screw.

12. Complete electrical box wiring and installation. Connect
line voltage leads as shown in Fig. 24. Use best practices
(NEC in U.S. and CSA C22.1 in Canada) for wire
bushings, strain relief, etc.

13. Reinstall cover to J--Box. Do not pinch wires between
cover and bracket.

POWER CORD INSTALLATION IN FURNACE

NOTE: Power cords must be able to handle the electrical

requirements listed in Table 7. Refer to power cord
manufacturer’s listings.

1. Remove cover from J--Box.

2. Route listed power cord through 7/8--inch diameter hole in
J--Box.

3. Secure power cord to J--Box bracket with a strain relief
bushing or a connector approved for the type of cord used.

4. Secure field ground wire to green ground screw on J--Box
bracket.

5. Connect line voltage leads as shown in Fig. 24.

6. Reinstall cover to J--Box. Do not pinch wires between
cover and bracket.

BX. CABLE INSTALLATION IN FURNACE

1. Remove cover from J--Box.

2. Route BX cable into 7/8--inch diameter hole in J--Box.

3. Secure BX cable to J--Box bracket with connectors
approved for the type of cable used.

4. Secure field ground wire to green ground screw on J--Box
bracket.

5. Connect line voltage leads as shown in Fig. 24.

6. Reinstall cover to J--Box. Do not pinch wires between
cover and bracket.

24--V

WIRING

Make field 24--v connections at the 24--v terminal strip. (See Fig.

34.) Connect terminal Y/Y2 as shown in Fig. 27--33 for proper
cooling operation. Use only AWG No. 18, color--coded, copper
thermostat wire.

The 24--v circuit contains an automotive--type, 3--amp. fuse
located on the control. Any direct shorts during installation,
service, or maintenance could cause this fuse to blow. If fuse
replacement is required, use ONLY a 3--amp. fuse of identical
size.

J--BOX

J--BOX

312A

23

312A

See notes 2, 5, 8, 10, 11 and 12
on the page following these figures

Fig. 27 -- Two--Stage Furnace with Two--Speed Air

Conditioner

A03179

See notes 1, 2, 3, 4, 6, 8, 9, 10, 12, 13 and 15
on the page following these figures

A03178

Fig. 29 -- Two--Stage Furnace with Two--Speed Heat Pump

(Dual Fuel)

See notes 1, 2, 4, 6, 7, 9, 10, 11, and 15
on the page following these figures

A03180

Fig. 28 -- Two--Stage Furnace with Single--Speed Heat Pump

(Dual Fuel)

See notes 1, 2, 4, 11, 14, 15, and 16
on the page following these figures

Fig. 30 -- Dual Fuel Thermostat with Two--Stage Furnace

and Single--Speed Heat Pump

24

A03181

7

See notes 1, 2, 3, 4, 12, 13, 14, 15, and 17
on the page following these figures

A03182

Fig. 31 -- Dual Fuel Thermostat with Two--Stage Furnace

and Two--Speed Heat Pump

See notes 1 and 2 on the page
following these figures

Fig. 33 -- Single--Stage Thermostat with Two--Stage Furnace and Two--Speed Air Conditioner

See notes 2, 11, and 12 on the
page following these figures

A03183

Fig. 32 -- Two--Stage Thermostat with Two--Stage Furnace

and Two--Speed Air Conditioner

A03184

312A

NOTES: F o r Figu r e s 25 --- 31

1. Heat pump MUST have a high pressure switch for dual fuel appl ications.

2. Refer to outdoor equipment Installation Instructions for additional information and setup procedure.

3. Outdoor Air Temperature Sensor must be attached in all dual fuel applications.

4. Dip switch No. 1 on Thermidistat shou ld be set in OFF position for air conditioner installations. This is factory default.

5. Dip switch No. 1 on Thermidistat should be set in ON position for heat pump installations.

6. Dip switch No. 2 on Thermidistat should be set in OFF position for single ---speed compressor operation. This is factory default.

7. Dip switch No. 2 on Thermidistat should be set in ON position for two ---speed compressor operation.

8. Configuration Option No. 10 “Dual Fuel Selection” must be turned ON in all dual fuel applications.

9. NO connection should be made to the furnace HUM terminal when using a Thermidistat.

10. Optional connection: If wire is connected, dip switch SW1---2 on furnace control should be set in ON position to allow Thermidistat/Thermostat to control
furnace staging.

11. Optional connection: If wire is connected, ACRDJ jumper on furnace control should be removed to allow Thermidistat/Thermostat to control outdoorunit
staging.

12. When using both a two---stage furnace and a two---stage heat pump, the furnace must control its own high---stage heating operation via furnace control
algorithm.

13. The RVS Sensing terminal “L” should not be connected. This is internally used to sense defrost operation.

14. DO NOT SELECT the “FURNACE INTERFACE” or “BALANCE POINT” option on the two ---speed h eat pump control board. This is controlled internally by
the Thermidistat/Dual Fuel Thermostat.

15. Dip switch D on Dual Fuel Thermostat should be set in OFF position for single---speed compressor operation. This is factory default.

16. Dip switch D on Dual Fuel Thermostat should be set in ON position for two --- speed compressor operation.

25

ACCESSORIES

1. Electronic Air Cleaner (EAC)
Connect an accessory Electronic Air Cleaner (if used)
using 1/4--in female quick connect terminals to the two
male 1/4--in quick--connect terminals on the control board
marked EAC-- 1 and EAC--2. The terminals are rated for
115VAC, 1.0 amps maximum and are energized during
blower motor operation. (See Fig. 34.)

2. Humidifier (HUM)
Connect an accessory 24 VAC, 0.5 amp. maximum
humidifer (if used) to the 1/4--in male quick--connect
HUM terminal and COM--24V screw terminal on the
control board thermostat strip. The HUM terminal is
energized when gas valve relay (GVR) is energized. (See
Fig. 34.)

NOTE: A field--supplied, 115 --v controlled relay connected to
EAC terminals may be added if humidifier operation is desired
during blower operation.

312A

SETUP SWITCHES

LOW-HEAT ONLY AND

BLOWER OFF-DELAY

ON

W2

Y1 DHUM G COM

OFF

1 2 3

LHT
OFF
DLY

NOTE: DO NOT connect furnace control HUM terminal to
HUM (humidifier) terminal on Thermidistat, Zone Controller or
similar device. See Thermidistatt, Zone Controller, thermostat,
or controller manufacturer’s instructions for proper connection.

VENTING

The furnace shall be connected to a listed factory built chimney
or vent or a clay--tile lined masonry or concrete chimney. Venting
into an unlined masonry chimney or concrete chimney is
prohibited. When an existing Category I furnace is removed or
replaced, the original venting system may no longer be sized to
properly vent the attached appliances. An improperly sized
Category I venting system could cause the formation of
condensate in the furnace and vent, leakage of condensate and
combustion products, and spillage of combustion products into
the living space.

TWINNING AND/OR
COMPONENT TEST

TERMINAL

ACRDJ - AIR CONDITIONING

RELAY DISABLE JUMPER

24-V-THERMOSTAT
TERMINALS

HUMIDIFIER TERMINAL

(24-VAC 0.5 AMP MAX.)

3-AMP FUSE

LED OPERATION &

DIAGNOSTIC LIGHT

115-VAC (L2) NEUTRAL

CONNECTIONS

HI HEAT

LO HEAT

BLOWER SPEED

SELECTION TERMINALS

24V

WW1 Y/Y2 R

S

E

L

EAC-2

BLW

HI HEAT LO HEAT

SPARE-1

SPARE-2

TEST/TWIN

HUM

0.5-AMP024 VAC

FUSE 3-AMP

A

T

T

SEC-1 SEC-2

U

S

C

O

E

D

NEUTRAL-L2

COOL

SPARE-1 SPARE-2

Fig. 34 -- Furnace Control--PSC Blower Motor

ACRDJ

PLT

PL1

1

BHT/CLRBHI/LOR

1-AMP@115 VAC

EAC-1 PR-1

COOL

D

BLWR

L1

115-VAC (L1) LINE

VOLTAGE CONNECTION

EAC-1 TERMINAL

(115-VAC 1.0 AMP MAX.)

IDR

PL2

1

PL3 1

HSIR

HSI HI LO

TRANSFORMER 24-VAC

CONNECTIONS

PL1 - LOW VOLTAGE MAIN

HARNESS CONNECTOR

PL3

IHI/LOR

IDM

PL2 - HOT SURFACE

IGNITER & INDUCER

MOTOR CONNECTOR

A02017

26

!

WARNING

CARBON MONOXIDE POISONING HAZARD

Failure to follow this warning could result in personal
injury or death.

Failure to follow the steps outlined below for each
appliance connected to the venting system being placed into
operation could result in carbon monoxide poisoning or
death. The following steps shall be followed for each
appliance connected to the venting system being placed into
operation, while all other appliances connected to the
venting system are not in operation:

1. Seal any unused openings in venting system.

2. Inspect the venting system for proper size and
horizontal pitch, as required in the National Fuel Gas Code,
ANSI Z223.1/NFPA 54 or the CSA B149.1, Natural Gas
and Propane Installation Code and these instructions.
Determine that there is no blockage or restriction, leakage,
corrosion and other deficiencies, which could cause an
unsafe condition.

3. As far as practical, close all building doors and windows
and all doors between the space in which the appliance(s)
connected to the venting system are located and other
spaces of the building.

4. Close fireplace dampers.

5. Turn on clothes dryers and any appliance not connected
to the venting system. Turn on any exhaust fans, such as
range hoods and bathroom exhausts, so they are operating
at maximum speed. Do not operate a summer exhaust fan.

6. Follow the lighting instructions. Place the appliance
being inspected into operation. Adjust the thermostat so
appliance is operating continuously.

7. Test for spillage from draft hood equipped appliances at
the draft hood relief opening after 5 minutes of main burner
operation. Use the flame of a match or candle.

8. If improper venting is observed during any of the above
tests, the venting system must be corrected in accordance
with the National Fuel Gas Code, ANSI Z223.1/NFPA 54
and/or CSA B149.1, Natural Gas and Propane Installation
Code.

9. After it has been determined that each appliance
connected to the venting system properly vents when tested
as outlined above, return doors, windows, exhaust fans,
fireplace dampers and any other gas--fired burning
appliance to their previous conditions of use.

Vent system or vent connectors may need to be resized. Vent
systems or vent connectors must be sized to approach minimum
size as determined using appropriate table found in the NFGC or
CAN/CSA--B149.1--05.

GENERAL VENTING

Follow all safety codes for proper vent sizing and installation
requirements, including local building codes, the National Fuel
Gas Code ANSI Z223.1--2006/NFPA 54--2006 (NFGC), Parts 10
and 13 in the United States or the National Standard of Canada,
Natural Gas and Propane Installation Code CSA--B149.1--00
(CAN/CSA--B149.1--05), Section 8 and Appendix C in Canada,
the local building codes, and furnace and vent manufacturers’
instructions.

These furnaces are design-- certified as Category I furnaces in
accordance with ANSI Z21.47--2003/CSA 2.3--2003 and operate
with a non--positive vent static pressure to minimize the potential
for vent gas leakage. Category I furnaces operate with a flue loss
not less than 17% to minimize the potential for condensation in
the venting system. These furnaces are approved for common
venting and multi--story venting with other fan assisted or draft

REQUIREMENTS

hood equipped appliances in accordance with the NFCG or the
CAN/CSA--B149.1--05, local building codes, and furnace and
vent manufacturers’ instructions.

The following information and warning must be considered in
addition to the requirements defined in the NFGC or the
CAN/CSA--B149.1--05.

!

WARNING

CARBON MONOXIDE POISONING HAZARD

Failure to follow this warning could result in personal
injury or death.

Do not bypass the draft safeguard switch, as an unsafe
condition could exist which must be corrected.

1. If a vent (common or dedicated) becomes blocked, the
furnace will be shut off by the draft safeguard switch
located on the vent elbow.

2. Two--stage furnaces require Type B vent connectors
outside the casing in all configurations. Single wall vent
connector may be used inside the furnace casing with the
transition to Type B vent outside the furnace casing. Size
the connector so that the FAN-- Min vent connector
capacity is equal to or lower than the low fire rate of the
furnace and the FAN--Max vent connector capacity is
equal to or higher than the furnace high fire rate.

3. Do not vent this Category I furnace into a single wall
dedicated or common vent. The dedicated or common
vent is considered to be the vertical portion of the vent
system that terminates outdoors.

4. Vent connectors serving Category I furnaces shall not be
connected into any portion of a mechanical draft system
operating under positive pressure.

5. In the US: Do not vent this appliance with any solid fuel
burning appliance. In Canada: Check with the authority
having jurisdiction for approval on use with solid fuel
burning appliance.

6. Category I furnaces must be vented vertically or nearly
vertically unless equipped with a listed mechanical venter.
See the SIDEWALL VENTING section.

7. Do not vent this appliance into an unlined masonry
chimney. Refer to Chimney Inspection Chart, Fig. 35.

MASONRY CHIMNEY

NOTE: These furnaces are CSA design--certified for use in

exterior tile--lined masonry chimneys with a factory accessory
Chimney Adapter Kit. Refer to the furnace rating plate for correct
kit usage. The Chimney Adapter Kits are for use with ONLY
furnaces having a Chimney Adapter Kit number marked on the
furnace rating plate.

If a clay tile--lined masonry chimney is being used and it is
exposed to the outdoors below the roof line, relining might be
required. Chimneys shall conform to the Standard for Chimneys,
Fireplaces, Vents, and Solid Fuel Burning Appliances
ANSI/NFPA 211--2003 in the United States and to a Provincial or
Territorial Building Code in Canada (in its absence, the National
Building Code of Canada) and must be in good condition.

U.S.A.--Refer to Sections 13.1.9 and 13.2.20 of the NFGC or the
authority having jurisdiction to determine whether relining is
required. If relining is required, use a properly sized listed metal
liner, Type--B vent, or a listed alternative venting design.

NOTE: See the NFGC, 13.1.9 and 13.2.20 regarding alternative
venting design and the exception, which cover installations such
as the Chimney Adapter Kits KGACA02014FC and
KGACA02015FC, which are listed for use with these furnaces.

REQUIREMENTS

312A

27

CHIMNEY INSPECTION CHART

For additional requirements refer to the National Fuel Gas Code NFPA 54/ANSI Z223.1 and ANSI/NFPA 211

Chimneys, Fireplaces, Vents, and Solid Fuel Burning Appliances in the U.S.A. or to the Canadian

installation Code CSA-B149.1 in Canada.

312A

Crown

condition:

Missing mortar

or brick?

No

Is chimney

property lined with

clay tile liner?

Ye s

Is
liner and top
seal in good

condition?

Ye s

Debris

in cleanout?

Mortar, tile, metal vent,

fuel oil residue?

Ye s

No

Ye s

No

Rebuild

crown.

Repair

liner or top seal

or reline chimney as

necessary.

Repair

Mortar

or tile

debris?

Reline

Ye s

Remove mortar

and tile debris

No

Clay

tile misalignment,

missing sections,

gaps?

No

Condensate

drainage at bottom

of chimney?

No

Chimney

exposed to

outdoors below

roof line?

No

Chimney is

acceptable for use.

Remove metal vent

or liner.

Ye s

lined with properly

sized, listed liner or

Ye s

Ye s

No

No

Is chimney

Type-B vent?

Ye s

Is chimney

to be dedicated to

a single

furnace?

Consult

Part B of

chimney adapter venting

instructions for

application

suitability.

Suitable

Ye s

Install chimney

adapter per

instructions.

No

chimney adapter venting

Not Suitable

Not Suitable

Consult

Part C of

instructions for

application

suitability

Line chimney with property

sized, listed flexible metal

liner or Type-B vent per

NFGC or NSCNGPIC Vent

Sizing Tables and liner or

vent manufacturer’s

Installation instructions.

Suitable

Install chimney

adapter per

instructions.

Fig. 35 -- Chimney Inspection Chart

28

A03206

The Chimney Adapter Kit is a listed alternative venting system
for these furnaces. See the kit instructions for complete details.

Canada (and U.S.A.)--This furnace is permitted to be vented into
a clay tile--lined masonry chimney that is exposed to the outdoors
below the roof line, provided:

1. Vent connector is Type--B double--wall, and

2. This furnace is common vented with at least 1 draft
hoodequipped appliance, and

3. The combined appliance input rating is less than the
maximum capacity given in Table 8, and

4. The input rating of each space heating appliance is greater
than the minimum input rating given in Table 9 for the
local 99% Winter Design Temperature. Chimneys having
internal areas greater than 38 square inches require furnace
input ratings greater than the input ratings of these
furnaces. See footnote at bottom of Table 9, and

5. The authority having jurisdiction approves.

If all of these conditions cannot be met, an alternative venting
design shall be used, such as the listed chimney adapter kit with a
furnace listed for use with the kit, a listed chimney--lining system,
or a Type--B common vent.

Inspections before the sale and at the time of installation will
determine the acceptability of the chimney or the need for repair
and/or (re)lining. Refer to Fig. 35 to perform a chimney
inspection. If the inspection of a previously used tile--lined
chimney:

a. Shows signs of vent gas condensation, the chimney

should be relined in accordance with local codes and the
authority having jurisdiction. The chimney should be
relined with a listed metal liner, Type--B vent, or a listed
chimney adapterkitshallbeusedto reducecondensation.
If a condensate drain is required by local code, refer to
the NFGC, Section 10.9 for additional information on
condensate drains.

b. Indicates the chimney exceeds the maximum permissible

sizein thetables, the chimney should berebuilt or relined
to conform to the requirements of the equipment being
installed and the authority having jurisdiction.

A chimney without a clay tile liner, which is otherwise in good
condition, shall be rebuilt to conform to ANSI/NFPA 211 or be
lined with a UL listed (ULC listed in Canada) metal liner or UL
listed Type--B vent. Relining with a listed metal liner or Type--B
vent is considered to be a vent--in--a--chase.

If a metal liner or Type--B vent is used to line a chimney, no other
appliance shall be vented into the annular space between the
chimney and the metal liner.

Exterior Masonry Chimney FAN + NA
Installations with Type-- B Double--Wall V
Connectors

ENFPA & AGA

T

ent

Table 8 – Combined Appliance Maximum Input Rating in

Thousands of BTUH per Hour

VENT HEIGHT

(FT)

6 74 119 178 257

8 80 130 193 279
10 84 138 207 299
15 NR 152 233 334
20 NR NR 250 368
30 NR NR NR 404

INTERNAL AREA OF CHIMNEY

(SQ. IN.)

12 19 28 38

Table 9 – Minimum Allowable Input Rating of Space--Heat-

ing Appliance in Thousands of BTUH per Hour

VENT HEIGHT

(FT)

6 0 55 99 141

8 52 74 111 154

10 NR 90 125 169

15 NR NR 167 212

20 NR NR 212 258

30 NR NR NR 362

6 NR 78 121 166

8 NR 94 135 182

10 NR 111 149 198

15 NR NR 193 247

20 NR NR NR 293

30 NR NR NR 377

Temperature: --- 10 to 4_F*

6 NR NR 145 196

8 NR NR 159 213

10 NR NR 175 231

15 NR NR NR 283

20 NR NR NR 333

30 NR NR NR NR

Temperature: --- 11_Forlower

Not recommended for any vent configuration.

*The 99% Winter Design Dry--- Bulb (db) temperatures are found in the
1993 ASHRAE Fundamentals Handbook, Chapter 24, Table 1 (United
States) and 2 (Canada), or use the 99.6% heating db temperatures found
in th e 1997 or 2001 ASHRAE Fundamentals Handbook, Climatic Design
Information chapter, Table 1A (United States) and 2A (Canada).

INTERNAL AREA OF CHIMNEY

(SQ. IN.)

12 19 28 38

Local 99% Winter Design

Temperature: 17 to 26_F

Local 99% Winter Design

Temperature: 5 to 16_F*

Local 99% Winter Design

Local 99% Winter Design

APPLIANCE APPLICATION REQUIREMENTS

Appliance operation has a significant impact on the performance
of the venting system. If the appliances are sized, installed,
adjusted, and operated properly, the venting system and/or the
appliances should not suffer from condensation and corrosion.
The venting system and all appliances shall be installed in
accordance with applicable listings, standards, and codes.

The furnace should be sized to provide 100% of the design
heating load requirement plus any margin that occurs because of
furnace model size capacity increments. Heating load estimates
can be made using approved methods available from Air
Conditioning Contractors of America (Manual J); American
Society of Heating, Refrigerating, and Air--Conditioning
Engineers; or other approved engineering methods. Excessive
over--sizing of the furnace could cause the furnace and/or vent to
fail prematurely. When a metal vent or metal liner is used, the
vent must be in good condition and be installed in accordance
with the vent manufacturer’s instructions.

To prevent condensation in the furnace and vent system, the
following precautions must be observed:

1. The return-- air temperature must be at least 60_F db except

for brief periods of time during warm--up from setback at
no lower than 55_F(13_C) db or during initial start--up
from a standby condition.

2. Adjust the gas input rate per the installation instructions.
Low gas input rate causes low vent gas temperatures,

29

312A

causing condensation and corrosion in the furnace and/or
venting system. Derating is permitted only for altitudes
above 2000 ft

3. Adjust the air temperature rise to the midpoint of the rise
range or slightly above. Low air temperature rise can cause
low vent gas temperature and potential for condensation
problems.

4. Set the thermostat heat anticipator or cycle rate to reduce
short cycling.

Air for combustion must not be contaminated by halogen
compounds which include chlorides, fluorides, bromides, and
iodides. These compounds are found in many common home
products such as detergent, paint, glue, aerosol spray, bleach,
cleaning solvent, salt, and air freshener, and can cause corrosion
of furnaces and vents. Avoid using such products in the
combustion--air supply. Furnace use during construction of the
building could cause the furnace to be exposed to halogen
compounds, causing premature failure of the furnace or venting
system due to corrosion.

312A

Vent dampers on any appliance connected to the common vent
can cause condensation and corrosion in the venting system. Do
not use vent dampers on appliances common vented with this
furnace.

ADDITIONAL VENTING REQUIREMENTS

A 4 in. round vent elbow is supplied with the furnace. A 5 in. or
6 in. vent connector may be required for some model furnaces. A
field--supplied 4 in. to 5 in. or 4 in. to 6 in. sheet metal increaser
fitting is required when 5 in. or 6 in. vent connector is used. See
Fig. 36--48 Venting Orientation for approved vent configurations.

See Venting Notes after Fig. 48.

SEE NOTES: 1,2,3,4,7,8,9
on the pages following
these figures

Fig. 37 -- Upflow Application--Vent Elbow Right

A03209

SEE NOTES: 1,2,4,7,8,9
on the page following
these figures

Fig. 36 -- Upflow Application--Vent Elbow Up

A03208

SEE NOTES:1,2,3,4,5,7,8,9
on the page following
these figures

A03210

Fig. 38 -- Downflow Application--Vent Elbow Up then Left

30

SEE NOTES: 1,2,4,5,7,8,9
on the page following
these figures

SEE NOTES:1,2,3,4,5,7,8,9

312A

on the page following
these figures.

Fig. 39 -- Downflow Application--Vent Elbow Up

SEE NOTES: 1,2,4,5,6,7,8,9,10
on the page following these figures

A03211

A03212

Fig. 41 -- Downflow Application--Vent Elbow Up then Right

SEE NOTES: 1,2,4,7,8,9 on the page
following these figures

A03213

Fig. 42 -- Horizontal Left Application -- Vent Elbow Left

A03207

Fig. 40 -- Downflow Application--Vent Elbow Left then Up

SEE NOTES: 1,2,4,5,7,8,9 on the page
following these figures

Fig. 43 -- Horizontal Left Application -- Vent Elbow Right

then Up

31

A03214

SEE NOTES: 1,2,4,7,8,9 on the page
following these figures

SEE NOTES: 1,2,4,5,7,8,9 on the page
following these figures

Fig. 44 -- Horizontal Right Application -- Vent Elbow Right

312A

SEE NOTES: 1,2,4,5,7,8,9 on the page
following these figures

Fig. 45 -- Horizontal Left Application -- Vent Elbow Up

A03218

A03215

A03216

Fig. 46 -- Horizontal Left Application -- Vent Elbow Right

SEE NOTES: 1,2,4,5,7,8,9 on the page
following these figures

A03219

Fig. 47 -- Horizontal Right Application -- Vent Elbow Left

then Up

SEE NOTES: 1,2,4,5,7,8,9

A02068

Fig. 48 -- Horizontal Right Application--Vent Elbow Left

NOTES: Venting Notes for Fig. 36---48

1. For common vent, vent connector sizing and vent material: United States--- ---use the NFGC Canada--- --- use the CAN/CSA---B149.1 ---05

2. Immediately increase to 5---inch or 6---inch vent connector outside furnace casing when 5---inch vent connector is required, refer to Note 1 above.

3. Side outlet vent for upflow and downflow installations must use Type B vent immediately after exiting the furnace, except when KGAVG0101DFG, Downflow
VentGuardKit,isusedinthedownflowposition.

4. Type ---B vent where required, refer to Note 1 above.

5. Four ---inch single ---wall (26 ga. min.) vent must be used inside furnace casing and when the KGAVG0101DFG Downflow Vent Guard Kit is used external to
the furnace.

6. Accessory Downflow Vent Guard Kit, KGAVG0101DFG required in downflow installations with lower vent configuration.

7. Chimney Adapter Kit may be required for exterior masonry chimney applications. Refer to Chimney Adapter Kit, KGACA02014FC or KGACA02015FC, for
sizing and complete application details.

8. Secure vent connector to furnace elbow with (2) corrosion---resistant sheet metal screws, spaced approximately 180_ apart.

9. Secure all other single wall vent connector joints with (3) corrosion resistant screws spaced approximately 120_ apart. Secure Type --- B vent connectors per
vent connector manufacturer’s recommendations.

10. The total height of the vent and connector shall be at least seven feet for the 154,000 Btuh gas input rate model when installed in a downflow application
with furnace elbow turned to left side with the connector elbow outside furnace casing pointing upward. (See Fig. 41.)

32

Caution!! For the following applications, use the minimum vertical heights as specified below.

For all other applications, follow exclusively the National Fuel Gas Code

FURNACE

ORIENTATION

Downflow

Horizontal Left

Horizontal Left

Horizontal Left

Downflow

Downflow

NOTE: All vent configurations must also meet National Fuel Gas Code venting requirements NFGC. *4 in. inside casing or vent guard **Including 4 in. vent
section(s)

VENT ORIENTA-

TION

Vent elbow left, then

up Fig. 40

Vent elbow right,

then up Fig. 43

Vent Elbow up Fig.

44

Vent elbow right Fig.

45

Vent elbow up then

left Fig. 38

Vent elbow up, then

right Fig. 41

FURNACE IN-

PUT(BTUH/HR)

154,000
132,000

110,000(036/--- 12 only)

154,000
132,000
154,000
132,000

154,000 5 7

110,000 (036/--- 12 only) 5 10

110,000 (036/--- 12 only) 5 10

MINIMUM VENT

DIAMETER (IN.)*

5 12

5 7

5 7

MINIMUM VERTICAL VENT

HEIGHT (FT)**

312A

Fig. 49 -- Using Tin Snips to Cut Tie Points

!

CAUTION

CUT HAZARD

Failure to follow this caution may result in personal injury.

Sheet metal parts may have sharp edges or burrs. Use care
and wear appropriate protective clothing, safety glasses and
gloves when handling parts and servicing furnaces.

NOTE: Vent connector length for connector sizing starts at
furnace vent elbow. The 4 inch vent elbow is shipped for upflow
configuration and may be rotated for other positions. Remove the
3 screws that secure vent elbow to furnace, rotate furnace vent
elbow to position desired, re--install screws. The factory--supplied
vent elbow does NOT count as part of the number of vent
connector elbows.

The vent connector can exit the door through one of 5 locations
on the door.

1. Attach the single wall vent connector to the furnace vent
elbow, and fasten the vent connector to the vent elbow
with at least two field--supplied, corrosion--resistant, sheet
metal screws located 180_ apart.

NOTE: An accessory flue extension KGAFE0112UPH is
available to extend from the furnace elbow to outside the furnace
casing. If flue extension is used, fasten the flue extension to the
vent elbow with at least two field--supplied, corrosion--resistant,
sheet metal screws located 180_ apart. Fasten the vent connector

A04127

to the flue extension with at least two field--supplied, corrosion
resistant sheet metal screws located 180_ apart.

2. Vent the furnace with the appropriate connector as shown
in Fig. 36--48.

3. Orient the door to determine the correct location of the
door knockout to be removed.

4. Remove the correct U--shaped knockout in door.

NOTE: A number of techniques can be used to remove these
knockouts as seen in Fig. 49 through 53. The knockout in the
bottom of the door is unique due to its flanging and is more easily
removed by first cutting the two tie points at the edge of the door,
using aviation--type tin snips. (See Fig. 49.) A sharp blow to the
rounded end of the knockout (See Fig. 50.) will separate more tie
points and allow the knockout to be pulled loose. (See Fig. 51.)
Remove all burrs any sharp edges.

For the rectangular J--box knockout, use tin snips along the door
edge and use a sharp blow with a hammer to remove the
knockout. Remove any burrs and sharp edges.

For the knockouts in the other locations on the door (top and
sides), tin snips can also be used along the door edges; however,
the preferred method is to use a hammer and screwdriver to strike
a sharp blow (See Fig. 52.) directly to the knockout tie points or
use a hammer in the upper left corner of the desired knockout.
(See Fig. 53.) Remove any burrs and sharp edges.

NOTE: If a knockout does not come out after two sharp blows,
pull and snip as needed to remove the knockout. Additional
blows may cause damage to the door.

33

312A

Fig. 50 -- Rounded End of Knockout

A04128

A04130

Fig. 52 -- Hammer and Screwdriver Used for Knockout

A04131

Fig. 53 -- Remove Knockout with Hammer

!

CAUTION

BURN HAZARD

Failure to follow this caution may cause personal injury.

Hot vent pipe is within reach of small children when
installed in downflow position.

See the following instruction.

Fig. 51 -- Knockout Pulled Loose



A04129

An accessory Vent Guard Kit, KGAVG0101DFG is REQUIRED
for downflow applications for use where the vent exits through
the lower portion of the furnace casing door. Refer to the Vent
Guard Kit Instructions for complete details.

The horizontal portion of the venting system shall slope upwards
not less than 1/4--in. per linear ft (21 mm/m) from the furnace to
the vent and shall be rigidly supported every 5 ft or less with
metal hangers or straps to ensure there is no movement after
installation.

SIDEWALL VENTING

This furnace is not approved for direct sidewall horizontal
venting.

In the U.S.: Per section 10.3.4 of the NFGC, any listed
mechanical venter may be used, when approved by the authority
having jurisdiction.

34

In Canada: Per section 8.24.2 of the CAN/CSA--B149.1--05,
any listed mechanical venter may be used, when approved by the
authority having jurisdiction.

Select the listed mechanical venter to match the Btuh input of the
furnace being vented. Follow all manufacturers installation
requirements for venting and termination included with the listed
mechanical venter.

START--UP, ADJUSTMENT, AND SAFETY

CHECK

Step 1 — General

!

WARNING

FIRE HAZARD

Failure to follow this warning could result in personal
injury, death and/or property damage.

This furnace is equipped with manual reset limit switches in
the gas control area. The switches open and shut off power
to the gas valve if a flame roll--out or overheating condition
occurs in the gas control area. DO NOT bypass the
switches. Correct problem before resetting the switches.

1. Maintain 115--v wiring and ground. Improper polarity will
result in rapid flashing LED and no furnace operation.

2. Make thermostat wire connections at the 24--v terminal
block on the furnace control. Failure to make proper
connections will result in improper operation. (See Fig.

24.)

3. Gas supply pressure to the furnace must be greater than

4.5--in. wc (0.16 psig ) but not exceed 14--in. wc (0.5
psig).

!

CAUTION

CUT HAZARD

Failure to follow this caution may result in personal injury.

Sheet metal parts may have sharp edges or burrs. Use care
and wear appropriate protective clothing, safety glasses and
gloves when handling parts and servicing furnaces.

4. Check all manual--reset switches for continuity.

5. Install blower compartment door. Door must be in place to
operate furnace.

6. Setup switch descriptions The 2 stage furnace has DIP
switches used to select thermostat staging and blower off
delay timings. For switch locations on Furnace control
board, See Fig. 34 and 58.

7. Setup switch descriptions -- See Table 10.

Step 2 — Start--Up Procedures

1. Purge gas lines after all connections have been made.

2. Check gas lines for leaks.

!

WARNING

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal
injury, or death. Blower access door switch opens 115--v
power to control. No component operation can occur unless
switch is closed. Caution must be taken when manually
closing this switch for service purposes.

3. To Begin Component Self--Test:
Remove blower access door. Disconnect the thermostat R
lead from furnace control board. Manually close blower
door switch. Short (jumper) the COM--24v terminal on
control to the TEST/TWIN 3/16--inch quick--connect
terminal on control until the LED goes out (approximately
2 sec). Gas valve and humidifier will not be turned on.
Remove jumper from terminals. (See Fig. 34 and Table

10.)

NOTE: The furnace control allows all components, except the
gas valve, to be run for short period of time. This feature helps
diagnose a system problem in case of a component failure.
Component test feature will not operate if any thermostat signal is
present at the control.

Refer to service label attached to furnace or See Fig. 57.

Component test sequence is as follows:

a. LED will display previous status code 4 times.

b. Inducer motor starts on high--speed and continues to run

until Step g of component test sequence.

c. Hot surface igniter is energized for 15 sec., then off.

d. Blower motor operates on LO--HEAT speed for 10 sec.

e. Blower motor operates on HI--HEAT speed for 10 sec.

f. Blower motor operates on COOL speed for 10 sec.
g. Inducer motor goesto low--speed for 10 sec., then stops.

h. Reconnect R lead to furnace control board, remove tape

from blower door switch and re--install blower door.

4. Operate furnace per instruction on inner door.

5. Verify furnace shut down by lowering thermostat setting
below room temperature.

6. Verify furnace restarts by raising thermostat setting above
room temperature.

312A

!

WARNING

FIRE AND EXPLOSION HAZARD

Failure to follow this warning could cause personal injury,
death and/or property damage.

Never purge a gas line into a combustion chamber. Never
use matches, candles, flame, or other sources of ignition for
the purpose of checking leakage. Use a soap--and--water
solution to check for leakage.

35

Table 10 – 2--Stage Furnace Setup Switch Description

SETUP

SWITCH NO.

S W --- 1 Adaptive Heat Mode OFF

S W --- 2 Blower OFF delay ON or OFF

S W --- 3 Blower OFF delay ON or OFF

SWITCH

NAME

Step 3 — Adjustments

!

WARNING

FIRE HAZARD

Failure to follow this warning could result in injury, death
and/or property damage.

312A

DO NOT bottom out gas valve regulator adjusting screw.
This can result in unregulated manifold pressure and result
in excess over--fire and heat exchanger failures.

!

CAUTION

FURNACE DAMAGE HAZARD

Failure to follow this caution may result in reduced furnace
life.

DO NOT re--drill orifices. Improper drilling (burrs, out--of
round holes, etc.) can cause excessive burner noise and
misdirection of burner flames. This can result in flame
impingement of heat exchangers, causing failures. (See Fig.

50.)

Furnace gas input rate on rating plate is for installations at
altitudes up to 2000 ft Furnace input rate must be within +/--2%
of furnace rating plate input. For altitudes above 5500 ft, a
field--supplied high altitude pressure switch is required.

1. Determine the correct gas input rate.

In the U.S.:

The input rating for altitudes above 2,000 ft must be re­duced by 4% for each 1,000 ft above sea level.
For installations below 2000 ft, refer to the unit rating
plate.
For installations above 2000 ft, multiply the input on the
rating plate by the derate multiplier in Table 11 for the cor­rect input rate.

EXAMPLE:
88,000 BTUH INPUT FURNACE INSTALLED AT 4300 FT

Derate Furnace Input Rate

Furnace Input Rate X Multiplier = at Installation

at Sea Level Factor Altitude

88,000 X 0.90 = 79,200

In Canada: The input rating must be reduced by 10% for
altitudes of 2,000 ft to 4,500 ft above sea level by an
authorized Gas Conversion Station or Dealer. To
determine correct input rate for altitude, see example and
use 0.90 as derate multiplier factor.

2. Determine the correct orifice and manifold pressure
adjustment. All models in all positions except Low NOx

NORMAL

POSITION

DESCRIPTION

When OFF, allows 2- -- stage operation with a single stage thermostat.

Turn ON when using 2 stage thermostat to allow Low Heat opera ---

tion when R to W/W1 closes and High Heat operation when R to

Control blower OFF delay time. Used in conjunction with SW---3.

Control blower OFF delay time. Used in conjunction with SW---2.

OF USE

W/W1 and W2 close.

See Table 14.

See Table 14.

models in downflow and horizontal positions use Table 15
(22,000 BTUH per burner).

Table 11 – Altitude Derate Multiplier for U.S.A.

ALTITUDE

(FT)

0–2000 0 1.00
2001–3000 8–12 0.90
3001–4000 12–16 0.86
4001–5000 16–20 0.82
5001–6000 20–24 0.78
6001–7000 24–28 0.74
7001–8000 28–32 0.70
8001–9000 32–36 0.66

9001–10,000 36–40 0.62

* Derate multiplier factors are based on midpoint altitude for altitude
range.

%

OF DERATE

DERATE MULTIPLIER

FACTOR*

Low NOx models in downflow or horizontal positions MUST
use Table 16 (21,000 BTUH per burner). See input listed on
rating plate.

a. Obtain average yearly gas heat value (at installed altitude)

from local gas supplier.

b. Obtain average yearly gas specific gravity from local gas

supplier.

c. Find installation altitude in Table 15 or 16.

d. Find closest natural gas heat value and specific gravity

in Table 15 or 16

e. Follow heat value and specific gravity lines to point of

intersection to find orifice size and low--and high--heat
manifold pressure settings for proper operation.

f. Check and verify burner orifice size in furnace. NEVER

ASSUME ORIFICE SIZE. ALWAYS CHECK AND
VERIFY.

g. Replace orifice with correct size, if required by Table 15

or 16. Use only factory--supplied orifices. See
EXAMPLE 2.

EXAMPLE 2: (0--2000 ft altitude)

For 22,000 Btuh per burner application, use Table 15.

Heating value = 1000 Btuh/cu ft

Specific gravity = 0.62

Therefore: Orifice No. 43*

Manifold pressure: 3.7--in. wc for high--heat

1.6--in. wc for low--heat

* Furnace is shipped with No. 43 orifices. In this example

all main burner orifices are the correct size and do not need

to be changed to obtain proper input rate.

3. Adjust manifold pressure to obtain low fire input rate. (See
Fig. 54.)

36

a. Turn gas valve ON/OFF switch to OFF.

b. Remove manifold pressure tap plug from gas valve.

c. Connect a water column manometer or similar device to

manifold pressure tap.

d. Turn gas valve ON/OFF switch to ON.

e. Move setup switch LHT (SW--1) on furnace control to

ON position to lock furnace in low--heat operation. (See
Fig. 34 and Table 10.)

f. Manually close blower door switch.

g. Jumper R and W/W1 thermostat connections on control

to start furnace. (See Fig. 34.)

h. Remove regulator adjustment cap from low--heat gas

valve pressure regulators. (See Fig. 54.) Turn low--heat
adjusting screw (3/16 in. or smaller flat tipped
screwdriver) counterclockwise (out) to decrease input
rate or clockwise (in) to increase input rate.

c. Measure time (in sec) for gas meter to complete 1

revolution and note reading. The 2 or 5 cubic feet dial
provides a more accurate measurement of gas flow.

d. Refer to Table 12 for cubic ft of gas per hr.

e. Multiply gas rate cu ft/hr by heating value (Btuh/cu ft)

to obtain input. If clocked rate does not match required
input from Step 1, increase manifold pressure to increase
input or decrease manifold pressure to decrease input.
Repeat steps b through e until correct low heat input is
achieved. Re--install low--heat regulator seal cap on gas
valve.

5. Set low--heat temperature rise. The furnace must operate
within the temperature rise ranges specified on the furnace
rating plate. Do not exceed temperature rise ranges
specified on unit rating plate for high--and low--heat.
Determine the temperature rise as follows:

NOTE: Blower access door must be installed when taking
temperature rise reading. Leaving blower access door off will
result in incorrect temperature measurements.

!

WARNING

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal
injury or death.

Disconnect 115--v electrical power before changing speed
tap.

312A

A06667

Fig. 54 -- Redundant Automatic Gas Control Valve

NOTE: DO NOT set low--heat manifold pressure less than

1.4--in wc or more than 1.7--in. wc for natural gas. If manifold
pressure is outside this range, change main burner orifices.

i. Install low--heat regulator adjustment cap.

j. Leave manometer or similar device connected and

proceed to Step 4.

NOTE: If orifice hole appears damaged or it is suspected to have
been re--drilled, check orifice hole with a numbered drill bit of
correct size. Never re--drill an orifice. A burr--free and squarely
aligned orifice hole is essential for proper flame characteristics.

4. Verify natural gas low--heat input rate by clocking meter.

NOTE: Gas valve regulator adjustment caps must be in place for
proper input to be clocked.

a. Turn off all other gas appliances and pilots served by the

meter.

b. Run for 3 minutes in low--heat operation.

BURNER

ORIFICE

Fig. 55 -- Orifice Hole

a. Verify unit is running in low heat per Step 4. Place

thermometers in return and supply ducts as close to
furnace as possible. Be sure thermometers do not see
radiant heat from heat exchangers. Radiant heat affects
temperature rise readings. This practice is particularly
important with straight--run ducts.

b. When thermometer readings stabilize, subtract return--air

temperaturefrom supply--airtemperatureto determineair
temperature rise.

NOTE: If the temperature rise is outside this range, first check:

(1.) Gas input for low heat operation.
(2.) Derate for altitude if applicable.

(3.) Return and supply ducts for excessive restrictions

causing static pressures greater than 0.50--in. wc.

37

A93059

Table 12 – Gas Rate (cu ft/hr)

312A

SECONDS

FOR

REVOLUTION

1

10 360 720 1800 50 72 144 360
11 327 655 1636 51 71 141 355
12 300 600 1500 52 69 138 346
13 277 555 1385 53 68 136 340
14 257 514 1286 54 67 133 333
15 240 480 1200 55 65 131 327
16 225 450 1125 56 64 129 321
17 212 424 1059 57 63 126 316
18 200 400 1000 58 62 124 310
19 189 379 947 59 61 122 305
20 180 360 900 60 60 120 300
21 171 343 857 62 58 116 290
22 164 327 818 64 56 112 281
23 157 313 783 66 54 109 273
24 150 300 750 68 53 106 265
25 144 288 720 70 51 103 257
26 138 277 692 72 50 100 250
27 133 267 667 74 48 97 243
28 129 257 643 76 47 95 237
29 124 248 621 78 46 92 231
30 120 240 600 80 45 90 225
31 116 232 581 82 44 88 220
32 113 225 563 84 43 86 214
33 109 218 545 86 42 84 209
34 106 212 529 88 41 82 205
35 103 206 514 90 40 80 200
36 100 200 500 92 39 78 196
37 97 195 486 94 38 76 192
38 95 189 474 96 38 75 188
39 92 185 462 98 37 74 184
40 90 180 450 100 36 72 180
41 88 176 439 102 35 71 178
42 86 172 429 104 35 69 173
43 84 167 419 106 34 68 170
44 82 164 409 108 33 67 167
45 80 160 400 110 33 65 164
46 78 157 391 112 32 64 161
47 76 153 383 116 31 62 155
48 75 150 375 120 30 60 150
49 73 147 367

SIZE OF TEST DIAL

1 CU FT 2 CU FT 5 CU FT 1 CU FT 2 CU FT 5 CU FT

SECONDS

FOR

REVOLUTION

1

SIZE OF TEST DIAL

c. Adjust air temperature rise by adjusting blower speed.

Increase blower speed to reduce temperature rise.
Decrease blower speed to increase temperature rise. For
low heat, speed selection can be low (factory setting),
med--low, or med (5--speed blowers only).

d. Remove thermostat jumpers and release Blower Access

Door Switch.

e. To change motor speed selection for low heat, remove

blower motor lead from control LO--HEAT terminal.
(See Fig. 34.) Select desired blower motor speed lead
from 1 of the other terminals and relocate it to the
LO--HEAT terminal. (See Table 13 for lead color
identification). Reconnect original lead to SPARE
terminal.

f. Repeat steps a through e.

!

CAUTION

FURNACE OVERHEATING HAZARD

Failure to follow this caution may result in reduced furnace
life.

Recheck temperature rise. It must be within limits specified
on the rating plate. Recommended operation is at the
midpoint of rise range or slightly above.

g. When correct low heat input rate and temperature rise is

achieved, proceed to Step 6.

6. Adjust Manifold Pressure to Obtain High Heat Rate

a. Remove high fire regulator adjustment cap from gas

valve pressure regulator.

b. Manually close blower access door switch.

c. Jumper R, W/W1 and W2 thermostat connections on

control to run furnace in high heat. (See Fig. 34.)

d. d. Turn high--heat adjustingscrew (3/16 in. orsmallerflat

tipped screwdriver) counterclockwise (out) to decrease
input rate or clockwise (in) to increase rate.

e. Re--install high--fire adjustment caps.

f. Leave manifold or similar device connected and proceed

to Step 7.

NOTE: DO NOT set high--heat manifold pressure less than

3.2--in. wc or more than 3.8--in. wc for natural gas. If manifold
pressure is outside this range, change main burner orifices.

7. Verify natural gas high heat input rate by clocking meter.

NOTE: Gas valve regulator adjustment caps must be in place for
proper input to be clocked.

a. Turn off all other gas appliances and pilots served by the

meter.

b. Run for 3 minutes in high--heat operation.

c. Measure time (in sec) for gas meter to complete 1

revolution and note reading.

d. Refer to Table 12 for cubic ft of gas per hr.

e. Multiply gas rate cu ft/hr by heating value (Btuh/cu ft)

to obtain input.

NOTE: Using the 2 cu. ft or 5 cu. ft gas meter dial provides
greater accuracy in verifying gas input rate.

38

If clocked rate does not match required input from Step 1,
increase manifold pressure to increase input or decrease manifold
pressure to decrease input. Repeat steps b through e until correct
high heat input is achieved. Re--install high--heat regulator seal
cap on gas valve.

8. Set high heat temperature rise.
Jumper R to W/W1 and W2 to check high--gas--heat
temperature rise. Do not exceed temperature rise ranges
specified on furnace rating plate for high heat. The furnace
must operate within the temperature rise ranges specified
on the furnace rating plate.
Determine the air temperature rise as follows:

NOTE: Blower access door must be installed when taking
temperature rise reading. Leaving blower access door off will
result in incorrect temperature measurements.

a. Verify the furnace is operating in high heat per Step 6.

Place thermometers in return and supply ducts as close
to furnace as possible. Be sure thermometers do not see
radiant heat from heat exchangers. Radiant heat affects
temperature rise readings. This practice is particularly
important with straight--run ducts.

b. When thermometer readings stabilize, subtract return--air

temperaturefrom supply--airtemperatureto determineair
temperature rise.

NOTE: If the temperature rise is outside this range, first check:

(1.) Gas input for low--and high--heat operation.

(2.) Derate for altitude if applicable.

(3.) Return and supply ducts for excessive restrictions

causing static pressures greater than 0.50--in. wc.

(4.) Dirty filter.

c. Adjust air temperature rise by adjusting blower speed.

Increase blower speed to reduce temperature rise.
Decrease blower speed to increase temperature rise. For
high heat, speed selection can be med--high, med
(5--speed blowers only), or med--low (factory setting).

!

WARNING

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal
injury or death.

Disconnect 115--v electrical power before changing speed
tap.

d. To change motor speed selection for high heat, remove

blowermotor leadfrom controlHI--HEAT terminal.(See
Fig. 34.) Select desired blower motor speed lead from 1
of the other terminals and relocate it to the HI--HEAT
terminal. DO NOT use the low--heat tap that was already
set. (See Table 13 for lead color identification).
Reconnect original lead to SPARE terminal.

e. Repeat steps a thru e.

f. When correct high heat input rate and temperature rise is

achieved, turn gas valve ON/OFF switch to OFF.
g. Release Blower Access Door switch.

h. Remove manometer or similar device from gas valve.

i. Re--install manifold pressure tap plug in gas valve (use

3/16 in. head allen wrench). (See Fig 54.)

!

WARNING

FIRE HAZARD

Failure to reinstall manifold pressure tap plug in gas valve
could result in personal injury, property damage or death.

Reinstall manifold pressure tap plug in gas valve to prevent
gas leak.

j. Remove thermostat jumper wire from furnace control

board.

k. Turn LHT switch OFF.

l. Turn gas valve ON/OFF switch to ON.

m. Proceed to Step 9, “Set Blower Off Delay” before

installing blower access door.

!

CAUTION

FURNACE OVERHEATING HAZARD

Failure to follow this caution may result in reduced furnace
life.

Recheck temperature rise. It must be within limits specified
on the rating plate. Recommended operation is at the
midpoint of rise range or slightly above.

9. Set Blower Off Delay

a. Remove Blower Access Door if installed.

b. Turn Dip switch 2 and 3 ON or OFF for desired blower

off delay. (See Table 14 and Fig 34.)

10. Set thermostat heat anticipator.

a. Mechanical thermostat -- Set thermostat heat anticapator

to match the amp. draw of the electrical components in
the R--W/W1 circuit. Accurate amp. draw readings can
be obtainedatthewires normallyconnectedto thermostat
subbase terminals, R and W. The thermostat anticipator
should NOT be in the circuit while measuring current.

(1.) Set LHT switch on furnace control board to ON.

(2.) Remove thermostat from sub--base or from wall.

(3.) Connect an amp. meter as shown in Fig. 56 across

the R and W subbase terminals or R and W wires at
wall.

(4.) Record amp. draw across terminals when furnace is

in low heat and after blower starts.

(5.) Set heat anticipator on thermostat per thermostat

instructions and install on subbase or wall.

(6.) Turn LHT switch OFF.
(7.) Install blower access door.

b. Electronic thermostat: Set cycle rate for 3 cycles per hr.

11. Set airflow CFM for cooling
Select the desired blower motor speed lead for cooling
airflow. See Table 5--Air Delivery--CFM (With Filter). See
Table 13 for lead color identification.

Table 13 – Speed Selection

COLOR SPEED AS SHIPPED

White Common BLW
Black High COOL

Yellow M e d --- H ig h SPARE

Orange† Med SPARE

Blue M e d --- L o w HI---HEAT

* Continuous---blower speed ---as shipped default
{ Not all models equipped with 5 speed motors

39

Red Low* LO HEAT

312A

Table 14 – 2--Stage Furnace Blower OFF delay Setup Switch

312A

DESIRED HEATING MODE

BLOWER OFF DELAY (SEC.)

90 OFF OFF
120 OFF ON
150 ON OFF
180 ON ON

EXAMPLE:

THERMOSTAT SUBBASE
TERMINALS WITH
THERMOSTAT REMOVED
(ANITICIPATOR, CLOCK, ETC.,
MUST BE OUT OF CIRCUIT.)

R Y W G

10 TURNS

FROM UNIT 24-V
CONTROL TERMINALS

5.0 AMPS ON AMMETER
10 TURNS AROUND JAWS

SETUP SWITCH

S W --- 2

HOOK-AROUND
AMMETER

0.5 AMPS FOR THERMOSTAT

=

ANTICIPATOR SETTING

SETUP SWITCH

S W --- 3

Fig. 56 -- Amp. Draw Check with Ammeter

Step 4 — Check Safety Controls

The flame sensor, gas valve, and pressure switch were all checked
in the Start--up procedure section as part of normal operation.

1. Check Main Limit Switch(es)
This control shuts off combustion system and energizes
air--circulating blower motor, if furnace overheats. By
using this method to check limit control, it can be
established that limit is functioning properly and will
operate if there is a restricted return--air supply or motor
failure. If limit control does not function during this test,
cause must be determined and corrected.

a. Run furnace for at least 5 minutes.

b. Gradually block off return air with a piece of cardboard

or sheet metal until the limit trips.

c. Unblock return air to permit normal circulation.

d. Burners will re--light when furnace cools down.

2. Check draft safeguard switch.
The purpose of this control is to cause the safe shutdown
of the furnace during certain blocked vent conditions.

a. Verify vent pipe is cool to the touch.

b. Disconnect power to furnace and remove ventconnector

from furnace vent elbow.

c. Restore power to furnace and set room thermostat above

room temperature.

d. After normal start--up, allow furnace to operate for 2

minutes, then block vent elbow in furnace 80% of vent
area with a piece of flat sheet metal.

e. Furnace should cycleoffwithin2 minutes.Ifgas does not

shut off within 2 minutes, determine reason draft

A96316

safeguard switch did not function properly and correct
condition.

f. Remove blockage from furnace vent elbow.

g. Switch will auto--reset when it cools.

h. Re--install vent connector.

NOTE: Should switch remain open longer than 3 minutes,
furnace control board will lockout the furnace for 3 hours. To
reset furnace control board, turn thermostat below room
temperature or from HEAT to OFF and turn 115--v power OFF,
then back ON.

3. Check Pressure Switch(es)
This control proves operation of the draft inducer blower.

a. Turn off 115--v power to furnace.

b. Disconnect inducer motor lead wires from wire harness.

c. Turn on 115--v power to furnace.

d. Set thermostat to “call for heat” and wait 1 minute. When

pressure switch is functioning properly, hot surface
igniter should NOT glow and control diagnostic light
flashes a status code 32. Ifhot surfaceigniter glowswhen
inducer motor is disconnected, shut down furnace
immediately.

e. Determine reason pressure switch did not function

properly and correct condition.

f. Turn off 115--v power to furnace.

g. Reconnect inducer motor wires, replace outer door, and

turn on 115--v power.

h. Blower will run for 90 seconds before beginning thecall

for heat again.

i. Furnace should ignite normally.

40

Step 5 — Checklist

1. Put away tools and instruments. Clean up debris.

2. Verify that switches for LHT and OFF--DELAY are
blower OFF--DELAY are selected as desired.

3. Verify that blower and burner access doors are properly
installed.

4. Cycle test furnace with room thermostat.

5. Check operation of accessories per manufacturerfs
instructions.

6. Review User’s Guide with owner.

7. Attach literature packet to

furnace.

312A

41

Table 15 – Orifice Size and Manifold Pressure for Gas Input Rate

(Tabulated Data Based on 22,000 Btuh High--Heat/14,500 Btuh for Low--Heat per Burner, Derated 4% for Each 1000 Ft Above Sea

Level)

ALTITUDE RANGE

(FT)

U.S.A.

and

Canada

ALTITUDE RANGE

312A

U.S.A.

and

Canada

ALTITUDE RANGE

U.S.A.

Only

ALTITUDE RANGE

U.S.A.

Only

ALTITUDE RANGE

U.S.A.

Only

* Orifice numbers 43 are factory installed

0 to 2000

(FT)

U.S.A.

Altitudes

2001 to

3000 or

Canada

Altitudes

2001 to

4500

(FT)

3001 to

4000

(FT)

4001 to

5000

(FT)

5001 to

6000

AVG. GAS

HEAT VALUE

(BTUH/CU

FT)

900 42 3.5/1.5 42 3.6/1.6 42 3.7/1.6 41 3.5/1.5
925 42 3.3/1.4 42 3.4/1.5 42 3.5/1.5 42 3.7/1.6
950 43 3.8/1.7 42 3.3/1.4 42 3.4/1.5 42 3.5/1.5

975 43 3.6/1.6 43 3.8/1.6 42 3.2/1.4 42 3.3/1.4
1000 43 3.5/1.5 43 3.6/1.6 43 3.7/1.6 43 3.8/1.7
1025 43 3.3/1.4 43 3.4/1.5 43 3.5/1.5 43 3.6/1.6
1050 44 3.6/1.6 43 3.2/1.4 43 3.4/1.5 43 3.5/1.5
1075 44 3.4/1.5 44 3.5/1.5 43 3.2/1.4 43 3.3/1.4
1100 44 3.3/1.4 44 3.4/1.5 44 3.5/1.5 43 3.2/1.4

AVG. GAS

HEAT VALUE

(BTUH/CU

FT)

800 42 3.4/1.5 42 3.5/1.5 42 3.6/1.6 42 3.7/1.6

825 42 3.2/1.4 42 3.3/1.4 42 3.4/1.5 42 3.5/1.5

850 43 3.7/1.6 43 3.8/1.6 42 3.2/1.4 42 3.3/1.4

875 43 3.5/1.5 43 3.6/1.6 43 3.7/1.6 43 3.8/1.7

900 43 3.3/1.4 43 3.4/1.5 43 3.5/1.5 43 3.6/1.6

925 44 3.5/1.5 43 3.2/1.4 43 3.3/1.4 43 3.4/1.5

950 44 3.4/1.5 44 3.5/1.5 44 3.6/1.6 43 3.2/1.4

975 44 3.2/1.4 44 3.3/1.4 44 3.4/1.5 44 3.5/1.5
1000 45 3.7/1.6 45 3.8/1.7 44 3.2/1.4 44 3.4/1.5

AVG. GAS

HEAT VALUE

(BTUH/CU

FT)

775 42 3.2/1.4 42 3.3/1.4 42 3.4/1.5 42 3.5/1.5

800 43 3.6/1.6 43 3.8/1.6 42 3.2/1.4 42 3.3/1.4

825 43 3.4/1.5 43 3.5/1.5 43 3.7/1.6 43 3.8/1.6

850 43 3.2/1.4 43 3.3/1.4 43 3.4/1.5 43 3.6/1.5

875 44 3.5/1.5 44 3.6/1.6 43 3.3/1.4 43 3.4/1.5

900 44 3.3/1.4 44 3.4/1.5 44 3.5/1.5 43 3.2/1.4

925 45 3.8/1.6 44 3.2/1.4 44 3.3/1.5 44 3.4/1.5

950 46 3.8/1.6 45 3.7/1.6 45 3.8/1.7 44 3.3/1.4

AVG. GAS

HEAT VALUE

(BTUH/CU

FT)

750 43 3.6/1.6 43 3.8/1.6 42 3.2/1.4 42 3.3/1.4

775 43 3.4/1.5 43 3.5/1.5 43 3.6/1.6 43 3.8/1.6

800 43 3.2/1.4 43 3.3/1.4 43 3.4/1.5 43 3.5/1.5

825 44 3.4/1.5 44 3.6/1.5 43 3.2/1.4 43 3.3/1.4

850 44 3.2/1.4 44 3.4/1.5 44 3.5/1.5 44 3.6/1.6

875 45 3.7/1.6 45 3.8/1.7 44 3.3/1.4 44 3.4/1.5

900 46 3.7/1.6 46 3.8/1.7 45 3.7/1.6 44 3.2/1.4

925 46 3.5/1.5 46 3.6/1.6 46 3.7/1.6 46 3.8/1.7

AVG. GAS
HEAT VALUE
AT ALTITUDE

(BTUH/CU

FT)

725 43 3.4/1.5 43 3.5/1.5 43 3.6/1.6 43 3.7/1.6
750 43 3.2/1.4 43 3.3/1.4 43 3.4/1.5 43 3.5/1.5
775 44 3.4/1.5 44 3.5/1.5 43 3.2/1.4 43 3.3/1.4
800 44 3.2/1.4 44 3.3/1.4 44 3.4/1.5 44 3.5/1.5
825 46 3.8/1.7 45 3.8/1.6 44 3.2/1.4 44 3.3/1.4
850 46 3.6/1.6 46 3.7/1.6 46 3.8/1.7 45 3.8/1.6
875 47 3.8/1.7 46 3.5/1.5 46 3.6/1.6 46 3.7/1.6
900 47 3.6/1.6 47 3.8/1.6 46 3.4/1.5 46 3.5/1.5

0.58 0.60 0.62 0.64

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Manifold
Pressure

0.58 0.60 0.62 0.64
Manifold

Pressure

0.58 0.60 0.62 0.64
Manifold

Pressure

0.58 0.60 0.62 0.64
Manifold

Pressure

0.58 0.60 0.62 0.64

Manifold
Pressure

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

Manifold

Pressure

Manifold

Pressure

Manifold

Pressure

Manifold

Pressure

Manifold

Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

42

Table 15 -- Orifice Size and Manifold Pressure for Gas Input Rate (cont.)

(Tabulated Data Based on 22,000 Btuh High-- Heat/14,500 Btuh for Low--Heat per Burner, Derated 4% for Each 1000 Ft Above Sea

Level)

AVG. GAS

ALTITUDE RANGE

(FT)

U.S.A.

Only

ALTITUDE RANGE

U.S.A.

Only

ALTITUDE RANGE

U.S.A.

Only

ALTITUDE RANGE

U.S.A.

Only

* Orifice numbers 43 are factory installed

6001 to

7000

(FT)

7001 to

8000

(FT)

8001 to

9000

(FT)

9001 to

10,000

HEAT VALUE
AT ALTITUDE

(BTUH/CU

FT)

675 43 3.4/1.5 43 3.5/1.5 43 3.6/1.6 43 3.7/1.6
700 44 3.6/1.6 43 3.3/1.4 43 3.4/1.5 43 3.5/1.5
725 44 3.4/1.5 44 3.5/1.5 44 3.6/1.6 43 3.2/1.4
750 45 3.8/1.7 44 3.3/1.4 44 3.4/1.5 44 3.5/1.5
775 46 3.7/1.6 45 3.7/1.6 45 3.8/1.7 44 3.2/1.4
800 46 3.5/1.5 46 3.6/1.6 46 3.8/1.6 45 3.7/1.6
825 47 3.7/1.6 46 3.4/1.5 46 3.5/1.5 46 3.6/1.6
850 47 3.5/1.5 47 3.6/1.6 47 3.8/1.6 46 3.4/1.5

AVG. GAS
HEAT VALUE
AT ALTITUDE

(BTUH/CU

FT)

650 44 3.6/1.6 43 3.2/1.4 43 3.4/1.5 43 3.5/1.5
675 44 3.3/1.5 44 3.5/1.5 44 3.6/1.6 43 3.2/1.4
700 45 3.8/1.6 44 3.2/1.4 44 3.3/1.4 44 3.4/1.5
725 46 3.7/1.6 46 3.8/1.7 45 3.7/1.6 44 3.2/1.4
750 46 3.4/1.5 46 3.6/1.5 46 3.7/1.6 46 3.8/1.6
775 47 3.6/1.6 47 3.8/1.6 46 3.4/1.5 46 3.6/1.5
800 47 3.4/1.5 47 3.5/1.5 47 3.7/1.6 47 3.8/1.6
825 48 3.7/1.6 48 3.8/1.6 47 3.4/1.5 47 3.6/1.5

AVG. GAS
HEAT VALUE
AT ALTITUDE

(BTUH/CU

FT)

625 44 3.3/1.5 44 3.5/1.5 44 3.6/1.6 43 3.2/1.4
650 45 3.7/1.6 44 3.2/1.4 44 3.3/1.4 44 3.4/1.5
675 46 3.6/1.6 46 3.8/1.6 45 3.7/1.6 45 3.8/1.7
700 47 3.8/1.7 46 3.5/1.5 46 3.6/1.6 46 3.7/1.6
725 47 3.6/1.6 47 3.7/1.6 47 3.8/1.7 46 3.5/1.5
750 48 3.8/1.7 47 3.5/1.5 47 3.6/1.6 47 3.7/1.6
775 48 3.6/1.5 48 3.7/1.6 48 3.8/1.7 47 3.5/1.5

AVG. GAS
HEAT VALUE
AT ALTITUDE

(BTUH/CU

FT)

600 45 3.7/1.6 45 3.8/1.7 44 3.3/1.4 44 3.4/1.5
625 46 3.6/1.6 46 3.7/1.6 46 3.8/1.7 45 3.8/1.6
650 47 3.8/1.6 46 3.4/1.5 46 3.6/1.5 46 3.7/1.6
675 47 3.5/1.5 47 3.6/1.6 47 3.7/1.6 46 3.4/1.5
700 48 3.7/1.6 48 3.8/1.7 47 3.5/1.5 47 3.6/1.6
725 48 3.5/1.5 48 3.6/1.6 48 3.7/1.6 48 3.8/1.7

SPECIFIC GRAVITY OF NATURAL GAS

0.58 0.60 0.62 0.64

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Manifold
Pressure

0.58 0.60 0.62 0.64

Manifold
Pressure

0.58 0.60 0.62 0.64

Manifold
Pressure

0.58 0.60 0.62 0.64

Manifold
Pressure

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

Manifold

Pressure

Manifold

Pressure

Manifold

Pressure

Manifold

Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

312A

43

Table 16 – Orifice Size and Manifold Pressure for Gas Input Rate

(Tabulated Data Based on 21,000 Btuh High--Heat/14,500 Btuh for Low--Heat Per Burner, Derated 4% for Each 1000 Ft Above Sea

level)

ALTITUDE RANGE

(FT)

U.S.A.

and

Canada

ALTITUDE RANGE

312A

U.S.A.

and

Canada

ALTITUDE RANGE

U.S.A.

Only

ALTITUDE RANGE

U.S.A.

Only

ALTITUDE RANGE

U.S.A.

Only

* Orifice numbers 43 are factory installed

0to

2000

(FT)

U.S.A.

Altitudes

2001 to
3000 or

Canada

Altitudes

2001 to

4500

(FT)

3001 to

4000

(FT)

4001 to

5000

(FT)

5001 to

6000

AVG. GAS

HEAT VALUE

(BTUH/CU F T)

900 42 3.2/1.5 42 3.3/1.6 42 3.4/1.6 42 3.5/1.7
925 43 3.7/1.8 43 3.8/1.8 42 3.2/1.5 42 3.3/1.6
950 43 3.5/1.7 43 3.6/1.7 43 3.7/1.8 43 3.8/1.8

975 43 3.3/1.6 43 3.4/1.6 43 3.5/1.7 43 3.7/1.7
1000 44 3.6/1.7 43 3.3/1.6 43 3.4/1.6 43 3.5/1.7
1025 44 3.4/1.6 44 3.6/1.7 43 3.2/1.5 43 3.3/1.6
1050 44 3.3/1.6 44 3.4/1.6 44 3.5/1.7 43 3.2/1.5
1075 45 3.8/1.8 44 3.2/1.5 44 3.3/1.6 44 3.4/1.6
1100 46 3.8/1.8 45 3.7/1.8 44 3.2/1.5 44 3.3/1.6

AVG. GAS

HEAT VALUE

(BTUH/CU F T)

800 43 3.8/1.8 42 3.2/1.5 42 3.3/1.6 42 3.4/1.6

825 43 3.5/1.7 43 3.7/1.7 43 3.8/1.8 42 3.2/1.5

850 43 3.3/1.6 43 3.5/1.6 43 3.6/1.7 43 3.7/1.8

875 43 3.2/1.5 43 3.3/1.6 43 3.4/1.6 43 3.5/1.7

900 44 3.4/1.6 44 3.5/1.7 43 3.2/1.5 43 3.3/1.6

925 44 3.2/1.5 44 3.3/1.6 44 3.5/1.6 44 3.6/1.7

950 45 3.7/1.8 45 3.8/1.8 44 3.3/1.6 44 3.4/1.6

975 46 3.7/1.8 46 3.8/1.8 45 3.8/1.8 44 3.2/1.5
1000 46 3.5/1.7 46 3.6/1.7 46 3.8/1.8 45 3.7/1.8

AVG. GAS

HEAT VALUE

(BTUH/CU F T)

775 43 3.5/1.7 43 3.7/1.7 43 3.8/1.8 42 3.2/1.5

800 43 3.3/1.6 43 3.4/1.6 43 3.5/1.7 43 3.7/1.7

825 44 3.6/1.7 43 3.2/1.5 43 3.3/1.6 43 3.4/1.6

850 44 3.4/1.6 44 3.5/1.7 44 3.6/1.7 43 3.2/1.5

875 45 3.8/1.8 44 3.3/1.6 44 3.4/1.6 44 3.5/1.7

900 46 3.8/1.8 45 3.8/1.8 44 3.2/1.5 44 3.3/1.6

925 46 3.6/1.7 46 3.7/1.8 45 3.7/1.8 45 3.8/1.8

950 46 3.4/1.6 46 3.5/1.7 46 3.7/1.7 46 3.8/1.8

AVG. GAS

HEAT VALUE

(BTUH/CU F T)

750 43 3.3/1.6 43 3.4/1.6 43 3.5/1.7 43 3.6/1.7

775 44 3.6/1.7 43 3.2/1.5 43 3.3/1.6 43 3.4/1.6

800 44 3.3/1.6 44 3.4/1.6 44 3.6/1.7 43 3.2/1.5

825 45 3.8/1.8 44 3.2/1.5 44 3.4/1.6 44 3.5/1.6

850 46 3.8/1.8 45 3.7/1.8 45 3.8/1.8 44 3.3/1.6

875 46 3.5/1.7 46 3.7/1.7 46 3.8/1.8 45 3.7/1.8

900 47 3.8/1.8 46 3.5/1.7 46 3.6/1.7 46 3.7/1.8

925 47 3.6/1.7 47 3.7/1.8 47 3.8/1.8 46 3.5/1.7

AVG. GAS
HEAT VALUE
AT ALTITUDE

(BTUH/CU F T)

725 44 3.5/1.7 43 3.2/1.5 43 3.3/1.6 43 3.4/1.6
750 44 3.3/1.6 44 3.4/1.6 44 3.5/1.7 43 3.2/1.5
775 45 3.7/1.8 44 3.2/1.5 44 3.3/1.6 44 3.4/1.6
800 46 3.7/1.8 46 3.8/1.8 45 3.8/1.8 44 3.2/1.5
825 46 3.5/1.7 46 3.6/1.7 46 3.7/1.8 46 3.8/1.8
850 47 3.7/1.8 47 3.8/1.8 46 3.5/1.7 46 3.6/1.7
875 47 3.5/1.7 47 3.6/1.7 47 3.7/1.8 46 3.4/1.6
900 48 3.8/1.8 47 3.4/1.6 47 3.5/1.7 47 3.7/1.7

0.58 0.60 0.62 0.64

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Manifold
Pressure

0.58 0.60 0.62 0.64
Manifold

Pressure

0.58 0.60 0.62 0.64
Manifold

Pressure

0.58 0.60 0.62 0.64
Manifold

Pressure

0.58 0.60 0.62 0.64
Manifold

Pressure

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Manifold

Pressure

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

44

Table 16 -- Orifice Size and Manifold Pressure for Gas Input Rate (cont.)

(Tabulated Data Based on 21,000 Btuh High--Heat/14,500 Btuh for Low--Heat Per Burner, Derated 4% for Each 1000 Ft Above

Sea level)

AVG. GAS

ALTITUDE RANGE

(FT)

U.S.A.

Only

ALTITUDE RANGE

U.S.A.

Only

ALTITUDE RANGE

U.S.A.

Only

ALTITUDE RANGE

U.S.A.

Only

* Orifice numbers 43 are factory installed

6001 to

7000

(FT)

7001 to

8000

(FT)

8001 to

9000

(FT)

9001 to

10,000

HEAT VALUE
AT ALTITUDE

(BTUH/CU F T)

675 44 3.5/1.7 43 3.2/1.5 43 3.3/1.6 43 3.4/1.6
700 44 3.3/1.6 44 3.4/1.6 44 3.5/1.7 43 3.2/1.5
725 45 3.7/1.8 45 3.8/1.8 44 3.3/1.6 44 3.4/1.6
750 46 3.6/1.7 46 3.8/1.8 45 3.7/1.8 45 3.8/1.8
775 46 3.4/1.6 46 3.5/1.7 46 3.6/1.7 46 3.8/1.8
800 47 3.6/1.7 47 3.8/1.8 46 3.4/1.6 46 3.5/1.7
825 47 3.4/1.6 47 3.5/1.7 47 3.6/1.7 47 3.8/1.8
850 48 3.7/1.7 48 3.8/1.8 47 3.4/1.6 47 3.5/1.7

AVG. GAS

HEAT VALUE

AT ALTITUDE )

650 44 3.3/1.6 44 3.4/1.6 44 3.5/1.7 43 3.2/1.5
675 45 3.7/1.8 45 3.8/1.8 44 3.3/1.6 44 3.4/1.6
700 46 3.6/1.7 46 3.7/1.8 46 3.8/1.8 45 3.8/1.8
725 47 3.8/1.8 46 3.5/1.7 46 3.6/1.7 46 3.7/1.8
750 47 3.5/1.7 47 3.7/1.8 47 3.8/1.8 46 3.5/1.6
775 48 3.8/1.8 47 3.4/1.6 47 3.6/1.7 47 3.7/1.7
800 48 3.6/1.7 48 3.7/1.8 48 3.8/1.8 47 3.4/1.6
825 48 3.3/1.6 48 3.5/1.6 48 3.6/1.7 48 3.7/1.8

625 45 3.7/1.8 45 3.8/1.8 44 3.3/1.6 44 3.4/1.6
650 46 3.6/1.7 46 3.7/1.8 46 3.8/1.8 45 3.8/1.8
675 47 3.8/1.8 46 3.4/1.6 46 3.5/1.7 46 3.7/1.7
700 47 3.5/1.7 47 3.6/1.7 47 3.7/1.8 46 3.4/1.6
725 48 3.7/1.8 48 3.8/1.8 47 3.5/1.7 47 3.6/1.7
750 48 3.5/1.7 48 3.6/1.7 48 3.7/1.8 48 3.8/1.8
775 49 3.8/1.8 48 3.4/1.6 48 3.5/1.7 48 3.6/1.7

AVG GAS
HEAT VALUE
AT ALTITUDE

(BTU/CU FT)

600 46 3.6/1.7 46 3.7/1.8 46 3.8/1.8 45 3.7/1.8
625 47 3.7/1.8 47 3.8/1.8 46 3.5/1.7 46 3.6/1.7
650 47 3.4/1.6 47 3.6/1.7 47 3.7/1.8 47 3.8/1.8
675 48 3.6/1.7 48 3.8/1.8 47 3.4/1.6 47 3.5/1.7
700 48 3.4/1.6 48 3.5/1.7 48 3.6/1.7 48 3.7/1.8
725 49 3.7/1.8 49 3.8/1.8 48 3.4/1.6 48 3.5/1.7

0.58 0.60 0.62 0.64

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Manifold
Pressure

0.58 0.60 0.62 0.64
Manifold

Pressure

0.58 0.60 0.62 0.64
Manifold

Pressure

0.58 0.60 0.62 0.64
Manifold

Pressure

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Orifice

No.

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Orifice

No.

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

Manifold
Pressure

SERVICE AND MAINTENANCE

!

PROCEDURES

WARNING

312A

!

WARNING

FIRE, PERSONAL INJURY AND UNIT DAMAGE
HAZARD

Failure to follow this warning could result in personal injury,
death and/or property damage.

The ability to properly perform maintenance on this
equipment requires certain knowledge, mechanical skills,
tools, and equipment. If you do not possess these, do not
attempt to perform any maintenance on this equipment other
than those procedures recommended in the User’s Manual.

ELECTRICAL SHOCK, FIRE OR EXPLOSION
HAZARD

Failure to follow this warning could result in personal injury
or death, or property damage.

Before servicing, disconnect all electrical power to furnace.
Verify proper operation after servicing.

45

!

CAUTION

UNIT OPERATION HAZARD

Failure to follow this caution may result in improper unit
operation or failure of unit components.

Label all wires prior to disconnection when servicing
controls. Wiring errors can cause improper and dangerous
operation.

Step 1 — Introduction

GENERAL

These instructions are written as if the furnace is installed in an
upflow application. An upflow furnace application is where the
blower is located below the combustion and controls section of
the furnace, and conditioned air is discharged upward. Since this
furnace can be installed in any of the 4 positions shown in Fig. 4,
you must revise your orientation to component location

312A

accordingly.

ELECTRICAL CONTROLS AND

!

WARNING

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal
injury or death.

There may be more than one electrical supply to the
furnace. Check accessories and cooling unit for additional
electrical supplies that must be shut off during furnace
servicing.

The electrical ground and polarity for 115--v wiring must be
properly maintained. Refer to Fig. 24 for field wiring information
and to Fig. 58 for furnace wiring information.

NOTE: If the polarity is not correct, the STATUS LED on the
control will flash rapidly and prevent the furnace from heating.
The control system also requires an earth ground for proper
operation of the control and flame--sensing electrode.

The 24--v circuit contains an automotive--type, 3--amp. fuse
located on the control. (See Fig. 32.) Any shorts of the 24--v
wiring during installation, service, or maintenance will cause this
fuse to blow. If fuse replacement is required, use ONLY a 3--amp.
fuse. The control LED will display status code 24 when fuse
needs to be replaced.

Proper instrumentation is required to service electrical controls.
The control in this furnace is equipped with a Status Code LED
(Light--Emitting Diode) to aid in installation, servicing, and
troubleshooting. It can be viewed through the sight glass in
blower access door. The furnace control LED is either ON
continuously, rapid flashing, or a code composed of 2 digits. The
first digit is the number of short flashes, the second digit is the
number of long flashes.

For an explanation of status codes, refer to service label located
on blower access door or Fig. 57, and the troubleshooting guide
which can be obtained from your distributor.

See Fig. 62 for a brief Troubleshooting guide.

For Controls with an Amber

The stored status codes will NOT be erased from the control
memory, if 115-- or 24--v power is interrupted. The control will
store up to five (5) status codes.

1. To retrieve status codes, proceed with the following:

NOTE: NO thermostat signal may be present at control, and all
blower--OFF delays must be completed.

WIRING

LED

a. Leave 115--v power to furnace turned on.

b. Remove outer access door.

c. Look into blower access door sight glass for currentLED

status. Removing blower access door will open blower
access doorswitch and terminate 115--v power to control
so that status code is not displayed.

d. BRIEFLY remove insulated terminal wire from the draft

safeguard (DSS) switch until LED goes out, then
reconnect it.

NOTE: If wire to DSS is disconnected longer than 4 sec, main
blower starts, and retrieval request is ignored.

2. When above items have been completed, the LED flashes
status code 4 times. Record this status code for further
troubleshooting. After the LED flashes status code four
times, BRIEFLY remove wire again from DSS switch
until LED goes out, then reconnect it to retrieve previous
status code (if available). Repeat as needed for more
previous status codes or until Code 11 appears.

Step 2 — Care and Maintenance

!

WARNING

FIRE OR EXPLOSION HAZARD

Failure to follow this warning could result in personal
injury, death and/or property damage.

Never store anything on, near, or in contact with the
furnace, such as:

1. Spray or aerosol cans, rags, brooms, dust mops,
vacuum cleaners, or other cleaning tools.

2. Soap powders, bleaches, waxes or other cleaning
compounds, plastic or plastic containers, gasoline,
kerosene, cigarette lighter fluid, dry cleaning fluids,
or other volatile fluids.

3. Paint thinners and other painting compounds, paper
bags, or other paper products. Explosure to these
materials could lead to corrosion of the heat
exchanger.

For continuing high performance and to minimize possible
furnace failure, periodic maintenance must be performed on this
furnace. Consult your local dealer about proper frequency of
maintenance and the availability of a maintenance contract.

!

WARNING

ELECTRICAL SHOCK AND FIRE HAZARD

Failure to follow this warning could result in personal
injury, death or property damage.

Turn off the gas and electrical supplies to the unit before
performing any maintenance or service. Follow the
operating instructions on the label attached to the furnace.

!

WARNING

CARBON MONOXIDE POISONING AND FIRE
HAZARD

Failure to follow this warning could result in personal
injury, death, and/or property damage.

Never operate unit without a filter or with filter access door
removed.

46

!

CAUTION

CUT HAZARD

Failure to follow this caution may result in personal injury.

Sheet metal parts may have sharp edges or burrs. Use care
and wear appropriate protective clothing, safety glasses and
gloves when handling parts and servicing furnaces.

The minimum maintenance on this furnace is as follows:

1. Check and clean air filter each month or more frequently if
required. Replace if torn.

2. Check blower motor and wheel for cleanliness each
heating and cooling season. Clean as necessary.

3. Check electrical connections for tightness and controls for
proper operation each heating season. Service as
necessary.

4. Inspect burner compartment before each heating season
for rust, corrosion, soot or excessive dust. If necessary,
have furnace and burner serviced by a qualified service
agency.

5. Inspect the vent pipe/vent system before each heating
season for rust, corrosion, water leakage, sagging pipes or
broken fittings. Have vent pipes/vent system serviced by a
qualified service agency.

6. Inspect any accessories attached to the furnace such as a
humidifier or electronic air cleaner. Perform any service or
maintenance to the accessories as recommended in the
accessory instructions.

If stat us code recall is needed, briefl y remove then reconnect one main limit wire to di splay last st ored status code. On RED LED boards do not remove power or blower door before init iating st atus code recall.

EACH OF THE FOLLOWING STATUS CODES IS A TWO DIGIT NUMBER WI TH THE FIRST DIGIT DETERMI NED BY THE NUMBER OF SHORT FLASHES AND THE SECOND DIGIT BY THE NUMBER OF LONG FLASHES.

11 NO PR EVIOUS CODE - Stored status code is erased automatically af ter 72 hours.

On RED LED boards stored status codes can also be erased when power
(115 VAC or 24 VAC) to control is interrupted.

12 BLOWER ON AFTER POWER UP (115 VAC or 24 VAC) -Blower runs for the

selected blower off-delay time, if unit is powered up during a call for heat
(R-W/W1 closed) or (R-W/W1) opens during blower on-delay.

13 LIMIT CIRCUIT LOCKOUT - Lockout occurs if a limit, dra ft safeguard, flame rollout,

or blocked vent switch (if used) is open longer than 3 minutes.

- Control will auto reset after three hours. - Refer to #33.

14 IGNITION LOCKOUT - Control will auto-reset after three hours. Refer to #34.
21 GAS H EATING LOCKOUT - Control will NOT auto reset.

Check for: - Mis-wired gas v alve - Defective control (valve relay)

22 ABNORMA L FLAME-PROVING SIGNAL - Flame is proved while gas v alve is de-

energized. Inducer will run until fault is cleared. Check for:

- Leaky gas valve - Stuck-open gas valve

23 PRES SURE SWITCH DID NOT OPEN Check for: - Obstructed pressure tubing

24 SECO NDARY VOLTAGE FUSE IS OPEN Check for: - Short circuit in secondary

voltage (24VAC) wiring.

31 HIGH-H EAT PRESSURE SWITCH OR RELAY DID NOT CLOSE OR REOPENED

Control relay may be defective, ref er to status code #32

COMPONENT TEST

To initiate the component test sequence, shut OFF the room thermostat or disconnect the
"R" thermostat lead. Briefly short the TEST/TWIN terminal to the "Com 24V" terminal.
Status LED will flash last status code and then turn ON the inducer motor. The inducer
motor will start in HIGH speed and remain on HIGH speed until the end of the test then
shift to LOW speed for 7 to 15 seconds. The hot s urface igniter, blower motor LO HEAT
speed, blower motor HI HEAT speed, and blower motor COOL speed will be turned ON for
10-15 seconds each. Gas Valve and Humidifier will not be turned on. When the blower is
turned OFF the inducer will be switched to low-speed for 10 seconds.

LED CODE

CONTINUOUS OFF - Check for 115VAC at L1 and L2, and 24VAC at SEC-1 and SEC-2.
CONTINUOUS ON - Control has 24VAC power.
RAPID FLASHING - Line voltage (115VAC) polarity reversed. If twinned, refer to twinning kit instructions.

- Pressure switch stuck closed

STATUS

32 LOW-HEAT PRESSURE SWITCH DID NOT CLOSE OR REOPENED - If open longer than

five minutes, inducer shuts off for 15 minutes before retry. If opens during blower on-delay
period, blower will come on for the selected blower off-delay. Check for:

- Excessive wind - Restricted vent - Defective inducer motor

- Proper vent sizing - Defective pressure switch - Low inducer voltage (115 VAC)

- Inadequate combustion air supply - Low inlet gas pressure (if LGPS u sed)

- Disconnected or obstructed pressure tubing

33 LIMIT CIRCUIT FAULT - Indicates a limit, draft safeguard, flame rollout, or blocked vent

switch (if used) is open. Blower will r un for 4 minutes or until open switch remakes
whichever is longer. If open longer th an 3 minutes, code changes to lockout #13. If open
less than 3 minutes status code #33 continues to flash until blower shuts off. Flame rollout
switch and BVSS require manual reset. Check for: - Dirty filter or restricted duct system

- Defective blower motor or capacitor - Proper vent sizing - Restricted vent

- Defective switch or connections - Loose blower wheel - Excessive wind

- Inadequate combustion air supply (Flame Roll-out Switch open).

34 IGNITION PROVING FAILURE - Control wil l try three more times before lockout #14 occurs.

If flame signal lost during blower on-delay period, blower will come on for the selected
blower off-delay. Check for: - Oxide buildup on fla me sensor (clean with fine stee l wool)

- Proper flame sense microamps (.5 microamps D.C. min., 4.0 - 6.0 nominal)

- Manual valve shut-off - Control ground continuity

- Gas valve defective or gas valve turned off - Low inlet gas pressure

- Inadequate flame carryover or rough ignition - Defective Hot Surface Ignitor

- Flame sensor must not be grounded

- Green/Yellow wire MUST be connected to furnace sheet metal

43 LOW-HEAT PRESSURE SWITCH OPEN WHILE HIGH-HEAT PRESSURE SWITCH IS

CLOSED - Ch eck for: - Disconnected or obstructed pressure tubing

- Mis-wired pressure switches - Low-heat pressure switch stuck open

- Low inlet gas pressure (if LGPS used)

45 CONTROL CIRCUITRY LOCKOUT Auto-reset after one hour lockout due to;

- Gas valve relay stuck open - Flame sense circuit failure - Software check error
Reset power to clear lockout. Replace control if status code repeats.

Fig. 57 -- Service Label

327598-101 REV. C

SERVICE

312A

A04210

47

312A

A07125

Fig. 58 -- Wiring Diagram

48

CLEANING AND/OR REPLACING AIR FILTER

The air filter arrangement will vary depending on the application.
NOTE: If the filter has an airflow direction arrow, the arrow

must point towards the blower.

!

CAUTION

CUT HAZARD

Failure to follow this caution may result in personal injury.

Sheet metal parts may have sharp edges or burrs. Use care
and wear appropriate protective clothing, safety glasses and
gloves when handling parts and servicing furnaces.

Media cabinet filter procedures:

NOTE: Media Cabinet is included with two--stage furnace.

Table 17 – Filter size information (in.)

FURNACE

CASING

WIDTH

14--- 1/2 16 X 25 X 1 14 X 25 X 1 Cleanable*

17--- 1/2 16 X 25 X 1 16 X 25 X 1 Cleanable*

21 16 X 25 X 1 20 X 25 X 1 Cleanable*

24 16 X 25 X 1 24 X 25 X 1 Cleanable*

*Recommended

1. Turn off electrical supply to furnace before removing filter
access door.

2. Remove filter cabinet door.

3. Slide filter out of cabinet.

4. If equipped with permanent, washable 1--in filter, clean
filter by spraying cold tap water through filter in opposite
direction of airflow. Rinse filter and let dry. Oiling or
coating of the filter is not recommended. See Table 17 for
size information.

5. If equipped with factory--specified disposable media filter,
replace only with media filter having the same part
number and size. For expandable replacement media, refer
to the instructions included with the replacement media. If
equipped with accessory KGAFR0301ALL external filter
rack. See Table 17.

6. Slide filter into cabinet.

7. Replace filter cabinet door.

8. Turn on electrical supply to furnace.

BLOWER MOTOR AND

!

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal
injury or death.

Blower access door switch opens 115--v power to control.
No component operation can occur unless switch is closed.
Caution must be taken when manually closing this switch
for service purposes.

NOTE: The blower wheel should not be dropped or bent as
balance will be affected.

FILTER SIZE

Side Return

Bottom Re -

turn

WHEEL

WARNING

FILTER TYPE

The following steps should be performed by a qualified
service agency.

To ensure long life and high efficiency, clean accumulated dirt
and grease from blower wheel and motor annually.

The inducer and blower motors are pre--lubricated and require no
additional lubrication. These motors can be identified by the
absence of oil ports on each end of the motor.

Clean blower motor and wheel as follows:

1. Turn off electrical supply to furnace.

2. Loosen the thumbscrew from outer door and remove outer
door.

3. For downflow or horizontal furnaces having vent pipes
within the furnace that pass in front of the blower access
door:

a. Disconnect vent connector from furnace vent elbow.

b. Disconnect and remove short piece of vent pipe from

within furnace.

4. Remove 2 screws from blower access door and remove
blower access door.

5. Disconnect blower leads from furnace control. Record
wire color and location for reassembly. All other factory
wires can be left connected, but field thermostat
connections may need to be disconnected depending on
their length and routing.

6. Remove 2 screws holding control box to blower shelf.

7. Hang control box from front of furnace casing and away
from blower compartment.

8. Remove 2 screws holding blower assembly to blower
deck and slide blower assembly out of furnace.

9. Clean blower wheel and motor using a vacuum with soft
brush attachment. Blower wheel blades may be cleaned
with a small paint or flux brush. Do not remove or disturb
balance weights (clips) on blower wheel blades.

10. Vacuum any loose dust from blower housing, wheel and
motor.

11. If a greasy residue is present on blower wheel, remove
wheel from the blower housing and wash it with an
appropriate degreaser. To remove wheel:

NOTE: Before disassembly, mark blower mounting arms, motor,
and blower housing so motor and each arm is positioned at the
same location during reassembly.

a. Disconnectcapacitorwires(ifequipped)and ground wire

attached to blower housing.

b. Remove screws securing cutoff plate and remove cutoff

plate from housing.

c. Loosen set screw holding blower wheel on motor shaft

(160+/--20 in.--lb. when reassembling).

d. Remove bolts holding motor to blowerhousing and slide

motorout of wheel (40+/--10 in.--lb. when reassembling).

e. Remove blower wheel from housing.
f. Clean wheel and housing.

12. Reassemble motor and blower by reversing steps 11e,
through 11a. Be sure to reattach ground wire to the blower
housing.

13. Verify that blower wheel is centered in blower housing
and set screw contacts the flat portion of the motor shaft.
Loosen set screw on blower wheel and reposition if
necessary.

14. Spin the blower wheel by hand to verify that the wheel
does not rub on the housing.

15. Reinstall blower assembly in furnace.

312A

49

16. Reinstall control box assembly in furnace.

!

CAUTION

UNIT DAMAGE HAZARD

Failure to follow this caution may result in shortened heat
exchanger life.

Heating fan speed(s) MUST be adjusted to provide proper
air temperature rise as specified on the rating plate.
Recommended operation is at the midpoint of the rise range
or slightly above. Refer to “SET TEMPERATURE RISE”
under START--UP, ADJUSTMENT, and SAFETY
CHECK.

NOTE: Refer to Table 13 for motor speed lead relocation if leads
were not identified before disconnection.

17. Reconnect blower leads to furnace control. Refer to

312A

furnace wiring diagram, and connect thermostat leads if
previously disconnected.

18. To check blower for proper rotation:

a. Turn on electrical supply.

b. Manually close blower access door switch.

NOTE: If thermostat terminals are jumpered at the time blower
access door switch is closed, blower will run for 90 sec before
beginning a heating or cooling cycle.

c. Perform component self--test as shown at the bottom of

the SERVICE label, located on the front of blower access
door.

d. Verify blower is rotating in the correct direction.

19. If furnace is operating properly, RELEASE BLOWER
ACCESS DOOR SWITCH. Remove any jumpers or
reconnect any disconnected thermostat leads. Replace
blower access door.

!

WARNING

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal
injury, or death.

Blower access door switch opens 115--v power to furnace
control. No component operation can occur unless switch is
closed. Exercise caution to avoid electrical shock from
exposed electrical components when manually closing this
switch for service purposes.

them thoroughly. A build--up of soot and carbon indicates that a
problem exists which needs to be corrected, such as improper
adjustment of manifold pressure, insufficient or poor quality
combustion air, incorrect size or damaged manifold orifice(s),
improper gas, or a restricted heat exchanger. Action must be taken
to correct the problem.

If it becomes necessary to clean the heat exchangers because of
dust or corrosion, proceed as follows:

1. Turn OFF gas and electrical power to furnace.

2. Remove outer access door.

3. Disconnect vent connector from furnace vent elbow.

4. For downflow or horizontal furnace having an internal
vent pipe, remove internal vent pipe within the casing.

5. Disconnect wires to the following components. Mark
wires to aid in reconnection of (be careful when
disconnecting wires from switches because damage may
occur):

a. Draft safeguard switch.

b. Inducer motor.

c. Pressure switches.

d. Limit overtemperature switch.

e. Gas valve.
f. Hot surface igniter.

g. Flame--sensing electrode
h. Flame rollout switches.

6. Remove screws that fasten the collector box assembly to
the cell panel. Be careful not to damage the collector box.
Inducer assembly and elbow need not be removed from
collector box.

7. Disconnect gas line from gas manifold.

8. Remove the 5 screws that attach the burner assembly to
the cell panel. The gas valve and individual burners need
not be removed from support assembly. Remove NOx
baffles if installed.

NOTE: Be very careful when removing burner assembly to
avoid breaking igniter. See Fig. 59 and 60 for correct igniter
location.

9/32˝

5/16˝

20. Downflow or horizontal furnaces with vent pipe through
furnace only:

a. Install and connect short pieceof vent pipe inside furnace

to existing vent.

b. Connect vent connector to vent elbow.

21. Turn on gas supply and cycle furnace through one
complete heating and cooling cycle. Verify the furnace
temperature rise as shown in Adjustments Section. Adjust
temperature rise as shown in Adjustments Section. If
outdoor temperature is below 70_F, turn off circuit breaker
to outdoor unit before running furnace in the cooling
cycle. Turn outdoor circuit breaker on after completing
cooling cycle.

CLEANING HEAT

The following steps should be performed by a qualified
service agency:

NOTE: If the heat exchangers get a heavy accumulation of soot

and carbon, they should be replaced rather than trying to clean

EXCHANGER

A05025

Fig. 59 -- Igniter Position--Side View

9. Using field--provided 25-- caliber rifle cleaning brush,
36--in. long 1/4” diameter steel spring cable, a variable
speed, reversible electric drill, and vacuum cleaner, clean
cells as follows:

50

a. Remove metal screw fitting from wire brush to allow

insertion into cable.

b. Insert the twisted wire end of brush into end of spring

cable, and crimp tight with crimping tool or crimp by
striking with ball--peen hammer. TIGHTNESS ISVERY
IMPORTANT.

NOTE: The materials needed in item 9 can usually be purchased
at local hardware stores.

(1.) Attach variable--speed, reversible drill to the end of

spring cable (end opposite brush).

(2.) Insert brush end of cable into the outlet opening of

cell and slowly rotate with drill. DO NOT force
cable. Gradually insert cable into upperpass of cell.
(See Fig. 61.)

(3.) Work cable in and out of cell 3 or 4 times to obtain

sufficient cleaning. DO NOT pull cable with great
force. Reverse drill and gradually work cable out.

(4.) Insert brush end of cable in burner inlet opening of

cell, and proceed to clean 2 lower passes of cell in
same manner as upper pass.

(5.) Repeat foregoing procedures until each cell in

furnace has been cleaned.

(6.) Using vacuum cleaner, remove residue from each

cell.

(7.) Using vacuum cleaner with soft brush attachment,

clean burner assembly.

(8.) Clean flame sensor with fine steel wool.
(9.) Install NOx baffles (if removed.)

(10.) Reinstall burner assembly. Center burners in cell

openings.

10. Remove old sealant from cell panel and collector box
flange.

11. Spray releasing agent on the heat exchanger cell panel
where collector box assembly contacts cell panel.

NOTE: A releasing agent such as cooking spray or equivalent
(must not contain corn or canola oil, aromatic or halogenated
hydrocarbons or inadequate seal may occur) and RTV sealant
(G.E. 162, 6702, or Dow--Corning 738) are needed before
starting installation. DO NOT substitute any other type of RTV
sealant. G.E. 162 (P771--9003) is available through RCD in 3--oz.
tubes.

12. Apply new sealant to flange of collector box and attach to
cell panel using existing screws, making sure all screws
are secure.

13. Reconnect wires to the following components (Use
connection diagram on wiring label, if wires were not
marked for reconnection locations.):

a. Draft safeguard switch.

b. Inducer motor.

c. Pressure switches.

d. Limit overtemperature switch.

e. Gas valve.

f. Hot surface igniter.
g. Flame--sensing electrode.

h. Flame rollout switches.

14. Reinstall internal vent pipe, if applicable.

15. Reinstall vent connector on furnace vent elbow. Securely
fasten vent connector to vent elbow with 2 field--supplied,
corrosion --resistant, sheet metal screws located 180_ apart.

1-7/8”

A01026

Fig. 60 -- Igniter Position -- Top View

A91252

Fig. 61 -- Cleaning Heat Exchanger Cell

16. Replace blower access door only, if it was removed.

17. Set thermostat above room temperature and check furnace
for proper operation.

18. Verify blower airflow and speed changes between heating
and cooling.

!

WARNING

FIRE OR EXPLOSION HAZARD

Failure to follow this warning could result in personal injury,
death and/or property damage.

Never use a match or other open flame to check for gas
leaks. Use a soap--and--water solution.

19. Check for gas leaks.

20. Replace outer access door.

Step 3 — Sequence of Operation

NOTE: Furnace control must be grounded for proper operation

or control will lockout. Control is grounded through green wire
connected to gas valve and burner bracket screw. Using the
schematic diagram in Fig. 58, follow the sequence of operation
through the different modes. Read and follow the wiring diagram
very carefully.

NOTE: If a power interruption occurs during a call for heat
(W/W1 or W/W1--and--W2), the control run the blower for the
selected blower off--delay period two seconds after power is
restored and if the thermostat is still calling for gas heating. The
LED light will flash code 12 during this period, after which the
LED will be ON continuous, as long as no faults are detected.
After this period, the furnace will respond to the thermostat
normally.

The blower door must be installed for power to be conducted
through the blower door interlock switch ILK to the furnace

312A

51

control CPU, transformer TRAN, inducer motor IDM, blower
motor BLWM, hot--surface igniter HSI, and gas valve GV.

1. Two--Stage Heating (Adaptive mode) with

Single--Stage Thermostat

(See Fig. 24 or 33 for thermostat connections)

NOTE: The low--heat only switch (LHT) selects either the
low--heat only operation mode when ON, (see item 2. below) or
the adaptive heating mode when OFF in response to a call for
heat. (See Fig. 34.) When the W2 thermostat terminal is energized
it will always cause high--heat operation when the R to W circuit
is closed, regardless of the setting of the low--heat only switch.
This furnace can operate as a two--stage furnace with a
single-- stage thermostat because the furnace control CPU includes
a programmed adaptive sequence of controlled operation, which
selects low--heat or high--heat operation. This selection is based
upon the stored history of the length of previous gas--heating
periods of the single--stage thermostat.

The furnace will start up in either low-- or high--heat. If the
furnace starts up in low--heat, the control CPU determines the

312A

low--heat on--time (from 0 to 16 minutes) which is permitted
before switching to high--heat.

If the power is interrupted, the stored history is erased and the
control CPU will select low--heat for up to 16 minutes and then
switch to high--heat, as long as the thermostat continues to call for
heat. Subsequent selection is based on stored history of the
thermostat cycle times.

The wall thermostat “calls for heat”, closing the R to W circuit.
The furnace control performs a self--check, verifies the low--heat
and high--heat pressure switch contacts LPS and HPS are open,
and starts the inducer motor IDM in high--speed.

a. Inducer Prepurge Period

(1.) If the furnace control CPU selects low--heat

operation the inducer motor IDM comes up to
speed, the low--heat pressure switch LPS closes, and
the furnace control CPU begins a 15--second
prepurge period. After the low--heat pressureswitch
re--closes the furnace control CPU will begin a
15--second prepurgeperiod,and continue to run the
inducer motor IDM at high--speed.

(2.) If the furnace control CPU selects high--heat

operation, the inducer motor IDM remains running
at high--speed, and the high--heat pressure switch
relay HPSR is de--energized to close the NC contact.
When sufficient pressure is available the high--heat
pressure switch HPS closes, and the high--heat gas
valve solenoid GV--HI is energized. The furnace
control CPU begins a 15--second prepurge period
after the low--heat pressure switch LPS closes. If the
high--heatpressure switch HPS fails to close and the
low-- heat pressure switch LPS closes, the furnace
will operate at low--heat gas flow rate until the
high--heat pressure switch closes for a maximum of
2 minutes after ignition.

b. Igniter Warm--Up--At the end of the prepurge period,

the (Hot Surface Igniter) HSI is energized for a
17--second igniter warm--up period.

c. Trial--for--Ignition Sequence--When the igniter

warm--up period is completed the main gas valve relay
contacts GVR--1 and --2 close to energize the gas valve
solenoid GV--M, the gas valve opens, and 24 vac power
is supplied for a field--installed humidifier at the HUM
terminal.The gas valve solenoidGV--M permitsgasflow
to the burners whereitis ignitedby the HSI. Five sec after
the GVR closes, a 2--sec flame proving period begins.
The HSI igniter will remain energized until the flame is
sensed or until the 2--sec flame proving period begins. If

the furnace control CPU selects high--heat operation, the
high--heat gas valve solenoid GV--HI is also energized.

d. Flame--Proving--When theburner flameis proved at the

flame--proving sensor electrode FSE, the inducer motor
IDM switches to low--speed unless running at
high--speed, and the furnace control CPU begins the
blower--ON delay period and continues to hold the gas
valve GV--M open. If the burner flame is not proved
within two seconds, the control CPU will close the gas
valve GV--M,and thecontrol CPU will repeatthe ignition
sequence for up to three more Trials-- For--Ignition before
going to Ignition-- Lockout. Lockout will be reset
automatically after three hours, by momentarily
interrupting 115 vac power to the furnace, or by
interrupting 24 vac power at SEC1 orSEC2 to thefurnace
controlCPU (not atW/W1, G, R,etc.). If flame is proved
when flame should not be present, the furnace control
CPU will lock out of Gas--Heating mode and operate the
inducermotor IDM on highspeed until flameisno longer
proved.

e. Blower--ON Delay --If the burner flame is proven the

blower--ON delay for low--heat and high--heat are as
follows:
Low--Heat--45 seconds after the gas valve GV--M is
energized the blower motor (BLWM) is energized at LO
HEAT speed.
High--Heat--25 seconds after the gas valve GV--M is
energized the BLWM is energized at HI HEAT speed.
Simultaneously, the electronic air cleaner (EAC--1)
terminal isenergized and remains energized as long asthe
BLWM is energized.

f. Switching from Low--to High--Heat--If the furnace

control CPU switches from low--heat to high--heat, the
furnace control CPU will switch the inducer motor IDM
speed from low to high. The high--heat pressure switch
relay HPSR is de--energized to close the NC contact.
When sufficient pressure is available the high--heat
pressure switch HPS closes, and the high--heat gas valve
solenoid GV--HI is energized. The blower motor BLWM
will switch to HI HEAT speed five seconds after the
furnace control CPU switches from low--heat to
high--heat.

g. Switching from High-- to Low--Heat--The furnace

control CPU will not switch from high--heat to low--heat
while thethermostat R--to--W circuit is closed when using
a singlestage thermostat.

h. Blower--OFF Delay--When thethermostatis satisfied, the

R to W circuit is opened, de--energizing the gas valve
GV--M, stopping gas flow to the burners, and
de--energizing the humidifier terminal HUM. The
inducer motor IDM will remain energized for a5--second
post--purge period. The blower motor BLWM and air
cleaner terminal EAC--1 will remain energized for 90,
120, 150, or 180 seconds (depending on selection at
blower--OFF delay switches). The furnace control CPU
is factory--set for a 120--second blower--OFF delay.

2. Two-- Stage Thermostat and Two--Stage Heating (See Fig.
32 for thermostat connections)

NOTE: In this mode the LHT must be ON to select the low--heat
only operation mode in response to closing the thermostat
R--to--W1 circuit. Closing the thermostat R--to--W1--and--W2
circuits always causes high--heat operation, regardless of the
setting of the low--heat--only switch.

The wall thermostat “calls for heat”, closing the R--to--W1 circuit
for low--heat or closing the R--to--W1 and--W2 circuits for
high--heat. The furnace control performs a self--check, verifies the

52

low-- heat and high--heat pressure switch contacts LPS and HPS
are open, and starts the inducer motor IDM in high--speed.

The start up and shut down functions and delays described in
item 1. above apply to the 2--stage heating mode as well, except
for switching from low-- to high--Heat and vice versa.

a. Switching from Low-- to High--Heat--If the thermostat

R--to-- W1 circuit is closed and the R--to--W2 circuit
closes, the furnace control CPU will switch the inducer
motor IDM speed from low to high. The high--heat
pressure switch relay HPSR is de--energized to close the
NC contact. When sufficient pressure is available the
high--heat pressure switch HPS closes,and the high--heat
gas valve solenoid GV--HI is energized. The blower
motorBLWM willswitch to HI HEAT speed five seconds
after the R--to--W2 circuit closes.

b. Switching from High-- to Low--Heat--If the thermostat

R--to--W2 circuitopens, and theR--to--W1 circuitremains
closed, the furnace control CPU will switch the inducer
motor IDM speed from high to low. The high--heat
pressure switch relay HPSR is energized to open the NC
contact and de--energizethehigh--heatgasvalvesolenoid
GV--HI.When the inducer motor IDM reduces pressure
sufficiently, the high-- heat pressure switch HPS will
open. The gas valve solenoid GV--M will remain
energized as long as the low--heat pressure switch LPS
remains closed. The blower motor BLWM will switch to
LO HEAT speed five seconds after the R--to--W2 circuit
opens.

3. Cooling Mode--The thermostat “calls for cooling.”
a. Single--Speed Cooling--

(See Fig. 28 for thermostat connections)
The thermostat closes the R--to--G--and--Y circuits. The
R--to-- Y circuit starts the outdoor unit, and the
R--to--G--and--Y/Y2 circuits start the furnace blower
motor BLWM on COOL speed.
The electronic air cleaner terminal EAC--1 is energized
with 115 vac when theblower motor BLWM isoperating.

When the thermostat is satisfied, the R--to --G and--Y
circuits are opened. The outdoor unit will stop, and the
furnace blower motor BLWM willcontinue operatingon
the COOL speed for an additional 90 seconds. Jumper
Y/Y2 to DHUM to reduce the cooling off--delay to 5
seconds. (See Fig. 25.)

b. Single--Stage Thermostat and Two--Speed Cooling

(Adaptive Mode)

(See Fig. 33 for thermostat connections)
This furnace can operate a two --speed cooling unit with
a single--stage thermostat because the furnace control
CPU includes a programmed adaptive sequence of
controlled operation, which selects low--cooling or
high--cooling operation. This selection isbased upon the
stored history of the length of previouscooling period of
the single--stage thermostat.

NOTE: The air conditioning relay disable jumper ACRDJ must
be connected to enable the adaptive cooling mode in response to
a call for cooling. (See Fig. 34.) When ACRDJ is in place, the
furnace control CPU can turn on the air conditioning relay ACR
to energize the Y/Y2 terminal and switch the outdoor unit to
high--cooling.

The furnace control CPU can start up the cooling unit in either
low-- or high--cooling. If starting up in low--cooling, the furnace
control CPU determines the low--cooling on--time (from 0 to 20
minutes) which is permitted before switching to high--cooling. If
the power is interrupted, the stored history is erased and the
furnace control CPU will select low--cooling for up to 20 minutes
and then energize the air conditioning relay ACR to energize the

Y/Y2 terminal and switch the outdoor unit to high--cooling, as
long as the thermostat continues to call for cooling. Subsequent
selection is based on stored history of the thermostat cycle times.
The wall thermostat “calls for cooling”, closing the
R--to--G--and--Y circuits. The R--to--Y1 circuit starts the outdoor
unit on low--cooling speed, and the R--to--G--and--Y1 circuits
starts the furnace blower motor BLWM at low--cool speed (same
speed as LO HEAT).
If the furnace control CPU switches from low--cooling to
high--cooling, the furnace control CPU will energize the air
conditioning relay ACR. When the air conditioning relay ACR is
energized the R--to--Y1--and--Y2 circuits switch the outdoor unit
to high--cooling speed, and the R--to--G--and--Y1--and--Y/Y2
circuits switch the furnace blower motor BLWM to COOL speed.

NOTE: When transitioning from low--cooling to high--cooling
the outdoor unit compressor will shut down for 1 minute while
the BLWM continues to run at low--cool speed (same speed as
LO--HEAT) until the outdoor unit compressor comes back on at
high speed.

The electronic air cleaner terminal EAC--1 is energized with 115
vac whenever the blower motor BLWM is operating. When the
thermostat is satisfied, the R--to--G--and--Y circuit are opened.
The outdoor unit stops, and the furnace blower BLWM and
electronic air cleaner terminal EAC--1 will remain energized for
an additional 90 seconds. Jumper Y1 to DHUM to reduce the
cooling off--delay to 5 seconds. (See Fig. 34.)

c. Two--Stage Thermostat and Two--Speed Cooling (See

Fig. 32 for thermostat connections)

NOTE: The air conditioning relay disable jumper ACRDJ must
be disconnected to allow thermostat control of the outdoor unit
staging. (See Fig. 34.)

The thermostat closes the R--to--G--and --Y1 circuits for
low--cooling or closes the R--to--G--and--Y1--and--Y2 circuits for
high--cooling. The R--to--Y1 circuit starts the outdoor unit on
low--cooling speed, and the R--to--G--and--Y1 circuit starts the
furnace blower motor BLWM on low-- cool speed (same speed as
LO HEAT). The R--to--Y1--and--Y2 circuits start the outdoor unit
on high--cooling speed, and the R--to--G--and-- Y/Y2 circuits start
the furnace blower motor BLWM on COOL speed. The
electronic air cleaner terminal EAC--1 is energized with 115 vac
whenever the blower motor BLWM is operating. When the
thermostat is satisfied, the R-- to-- G--and--Y1 or
R--to--G--and--Y1--and--Y2 circuits are opened. The outdoor unit
stops, and the furnace blower BLWM and electronic air cleaner
terminal EAC--1 will remain energized for an additional 90
seconds. Jumper Y1 to DHUM to reduce the cooling off--delay to
5 seconds. (See Fig. 34.)

4. Thermidistat Mode
(See Fig. 27 -- 29 for Thermidistat connections) The
dehumidification output, DHUM on the Thermidistat
should be connected to the furnace control thermostat
terminal DHUM. When there is a dehumidify demand, the
DHUM input is activated, which means 24 vac signal is
removed from the DHUM input terminal. In other words,
the DHUM input logic is reversed. The DHUM input is
turned ON when no dehumidify demand exists. Once 24
vac is detected by the furnace control on the DHUM input,
the furnace control operates in Thermidistat mode. If the
DHUM input is low for more than 48 hours, the furnace
control reverts back to non --Thermidistat mode.
The cooling operation described in item 3. above also
applies to operation with a Thermidistat. The exceptions
are listed below:

a. Low cooling -- When the R--to--G--and--Y1 circuit is

closed and there is a demand for dehumidification,the
furnace blower motor BLWM will continue running at
low-- cool speed (same speed as LO HEAT).

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53

312A

b. High cooling --When the R-- to--G--and--Y/Y2 circuit is

closed and there is a demand for dehumidification,the
furnace blower motor BLWM will drop the blower speed
from COOL to HI HEAT for a maximum of 10 minutes
before reverting back to COOL speed. If there is still a
demand for dehumidification after 20 minutes, the
furnace control CPU will drop the blower speed back to
HI HEAT speed. This alternating 10--minute cycle will
continue as long as there is a call for cooling.

c. Cooling off--delay -- When the gcall for coolingh is

satisfied and there is a demand for dehumidification, the
cooling blower--off delay is decreased from 90 seconds
to 5 seconds.

5. Continuous Blower Mode
When the R--to--G circuit is closed by the thermostat, the
blower motor BLWM will operate on continuous--blower
speed (can be set to LO HEAT, HI HEAT, or COOL
speed). Factory default is LO HEAT speed. Terminal
EAC--1 is energized as long as the blower motor BLWM is
energized. During a call for heat, the blower BLWM will
stop during igniter warm--up (17 seconds), ignition (7
seconds), and blower--ON delay (45 seconds in low--heat,
and 25 seconds in high--heat), allowing the furnace heat
exchangers to heat up more quickly, then restarts at the
end of the blower--ON delay period at LO HEAT or HI
HEAT speed respectively. The blower motor BLWM will
revert to continuous--blower speed after the heating cycle
is completed. In high--heat, the furnace control CPU will
hold the blower motor BLWM at HI HEAT speed during
the selected blower--OFF delay period before reverting to
continuous--blower speed.
When the thermostat “calls for low--cooling”, the blower
motor BLWM will switch to operate at low--cool speed
(same speed as LO HEAT). When the thermostat is
satisfied, the blower motor BLWM will operate an
additional 90 seconds on low--cool speed before reverting
back to continuous--blower speed.
When the thermostat “calls for high--cooling”, the blower
motor BLWM will operate at COOL speed. When the
thermostat is satisfied, the blower motor BLWM will
operate an additional 90 seconds on COOL speed before
reverting back to continuous--blower speed.
When the R--to--G circuit is opened, the blower motor
BLWM will continue operating for an additional 5
seconds, if no other function requires blower motor
BLWM operation.

Continuous Blower Speed Selection from Thermostat

To select different continuous--blower speeds from the
room thermostat, momentarily turn off the FAN switch or
pushbutton on the room thermostat for 1--3 seconds after
the blower motor BLWM is operating. The furnace control
CPU will shift the continuous--blower speed from the
factory setting of LO HEAT to HI HEAT speed.
Momentarily turning off the FAN switch again at the
thermostat will shift the continuous--blower speed from HI
HEAT to COOL. Repeating the procedure will shift the
continuous--blower speed from COOL to LO HEAT
speed. The selection can be changed as many times as
desired and is stored in the memory to be automatically
used following a power interruption.

NOTE: If the blower--off delay is set to the maximum, the
adjustable continuous--fan feature is locked (i.e., fan speed cannot
be changed from its current setting).

6. Heat Pump
(See Fig. 28 through 31 for thermostat connections)
When installed with a heat pump, the furnace control
automatically changes the timing sequence to avoid long
blower off times during demand defrost cycles. When the
R--to-- W/W1--and--Y1 or R--to--W/W1--and--Y1--and--G
circuits are energized the furnace control CPU will switch
to or turn on the blower motor BLWM at low--cool speed
(same speed as LO HEAT), and begin a low-- heat cycle.
The blower motor BLWM will remain on until the end of
the prepurge period, then shut off for 24 seconds then
come back on at LO HEAT speed. When the W/W1 input
signal disappears, the furnace control begins a normal
inducer post--purge period and the blower remains running
at LO HEAT speed. If the R--to-- W/W1--and--Y1--and--G
signals disappear at the same time, the blower motor
BLWM will remain on for the selected blower-- OFF delay
period. If the R--to--W/W1--and--Y1 signals disappear,
leaving the G signal, the blower motor BLWM will remain
on for the selected blower--OFF delay period then switch
to continuous--blower speed.
When the R--to--W/W1--and--Y/Y2, R--to--W/W1--and-­Y / Y 2 -- a n d -- G , R -- t o -- W / W 1 -- a n d -- Y 1 -- a n d -- Y / Y 2 , o r
R--to--W/W1--and-- Y1--and--Y/Y2--and--G circuits are
energized the furnace control CPU will switch to or turn
on the blower motor BLWM at COOL speed, and begin a
high--heat cycle. The blower motor BLWM will remain on
until the end of the prepurge period, then shut off for 24
seconds then come back on at HI HEAT speed. When the
W/W1 input signal disappears, the furnace control begins
a normal inducer post--purge period and the
blower switches to COOL speed after a 3 second delay. If
t h e R -- t o -- W / W 1 -- a n d -- Y / Y 2 -- a n d -- G o r R -- t o -- W / W 1 -- a n d

--Y1--and-- Y/Y2--and--G signals disappear at the same
time, the blower motor BLWM will remain on for the
selected blower--OFF delay period. If the R--to--W/W1-­a n d -- Y / Y 2 o r R -- t o -- W / W 1 -- a n d -- Y 1 -- a n d -- Y / Y 2 s i g n a l s
disappear, leaving the G signal, the blower motor BLWM
will remain on for the selected blower-- OFF delay period
then switch to continuous--blower speed.

Step 4 — Wiring Diagrams

Refer to wiring diagram, Fig. 58.

Step 5 — Troubleshooting

Refer to the service label. (See Fig. 57—Service Label.) The
Troubleshooting Guide can be a useful tool in isolating furnace
operation problems. Beginning with the word “Start,” answer
each question and follow the appropriate arrow to the next item.

The Guide will help to identify the problem or failed component.
After replacing any component, verify correct operation
sequence.

54

A02107A

NO

Is door switch closed?

NO

YES

Is door switch closed?

NO

YES

TROUBLESHOOTING GUIDE

Is circuit breaker closed?

NO

Is there 115V going to switch?

NO

YES

Check for continuity in wire from circuit

breaker to furnace.

YES

Replace door switch.

YES

Is 24V present at W/W1, W2, Y1, Y/Y2 or G

thermostat terminals on the furnace control?

NO

Does the control respond to W/W1, W2, Y1,

Y/Y2, and G (24V) thermostat signals?

NO

YES

Disconnect all the thermostat wires from the

furnace control.

YES

Run system through a low-heat, high-heat,

or cooling cycle to check operation. Status

NO

The thermostat is not compatible with the

furnace control. Either install a ballast resistor,

connect the Com24V thermostat terminal to

Does the problem repeat when using a

jumper wire?

YES

codes are erased after 72 hours. On RED

LED boards stored status codes can also be

erased whenever (115V or 24V) is interrupted.

Replace furnace control.

the thermostat, or replace the thermostat.

312A

NO

Close circuit breaker and go back to START.

Replace transformer.

Check room thermostat or

interconnecting cable.

Fig. 62 -- Troubleshooting Guide 2--Speed

Is there 115V at L1 and L2?

NO

START

Is LED status light on?

Is there 24V at SEC-1 and SEC-2?

YES

Replace furnace control.

Check for correct line voltage polarity. If

units are twinned, check for proper low-

voltage (24V) transformer phasing.

YES

NO

Is LED status light blinking rapidly

without a pause?

To recall status code briefly remove and reconnect one RED wire from the

draft safeguard switch to display stored status code. On RED LED control do

not remove power or blower access panel before initiating status code recall.

You can also recall the previous status code by momentarily shorting the

TEST/TWIN terminal to Com24V terminal until the LED goes out. LED will

flash the status code of the previous fault or status code #11 (1 short and 1

long flash) if there was no previous fault. After the control repeats the code

4 times, the control will start the component test sequence. Once indicated

the control will turn ON at HI HEAT speed. The inducer will run for the entire

component test. The HSI, blower motor LO HEAT speed, HI HEAT speed, and

COOL speed will run for 10 – 15 seconds each. Gas valve and humidifier will

not be turned on. When the blower motor is turned OFF the inducer will be

switched to low-speed for 10 seconds.

NO

YES

Is LED status light blinking ON/OFF slowly

with a combination of short and long flashes?

Determine status code. The status code is a

2 digit number with the first digit determined

by the number of short flashes and the second

digit by the number of long flashes?

55

Was there a previous status code other

than #11?

YES

Go to section below for the status code that

was flashed.

reset after 1 hour lockout due to:

45 CONTROL CIRCUITRY LOCKOUT Auto-

- Flame circuit failure.

- Gas valve relay stuck open.

- Software check error.

Reset power to clear lockout. Replace

control if code repeats.

Check for continuity in the harness and igniter.

Replace furnace control.

Replace defective component.

Check connections. If OK, replace control.

Check that all gas valves are turned on.

Replace valve.

Check for:

- Inadequate flame carryover or rough

ignition.

- Low inlet gas pressure.

- Proper firing rate.

(.045” nominal)

- Blocked or incorrect carry- over gap.

Allow blower to come on and repeat test to

check for intermittent operation.

Check connections and retry. If current is

near typical value (4.0-6.0 nominal) and

burners will not stay on, repeat check in high-

heat. If burners will still not stay on replace

control. If burners operate in high-heat then

switch to low-heat, check manifold pressure.

If OK, check burner carryover and flame

sensor location.

A05001

Replace electrode.

Replace furnace control.

312A

NO

tube.

WHILE HIGH-HEAT PRESSURE

SWITCH IS CLOSED - Check for:

- Low-heat pressure switch stuck open.

- Disconnected or obstructed pressure

- Miswired pressure switches.

- Low inlet gas pressure (if LGPS used).

43 LOW-HEAT PRESSURE SWITCH OPEN

NOT CLOSE OR REOPENED – If open

longer than 5 minutes, inducer shuts off

for 15 minutes before retry. If opens

during blower on-delay period, blower

will come on for the selected blower off-

delay. Check for:

- Proper vent sizing.

- Low inlet gas pressure (if LGPS used).

- Low inducer voltage (115V).

- Inadequate combustion air supply.

32 LOW-HEAT PRESSURE SWITCH DID

YES

Unplug igniter harness from control and

initiate another component test sequence.

Check for 115V between pin 1 and

NEUTRAL-L2 on the control. Was 115V

present for the 15 second period?

tubing.

- Disconnected or obstructed pressure

- Defective inducer motor.

- Defective pressure switch.

- Excessive wind.

- Restricted vent.

NO

YES

Reconnect the R thermostat lead and set

thermostat to call for heat. Connect voltmeter

across gas valve connections. Does gas

valve receive 24V?

Blower will run for 4 minutes or until

limit, draft safeguard, flame rollout, or

blocked vent shutoff switch* (if used) is

open.

open switch remakes whichever is longer.

If open longer than 3 minutes, code

33 LIMIT CIRCUIT FAULT – Indicates the

NO

YES

Does gas valve open and allow gas to flow?

changes to lockout #13. If open less

than 3 min. status code #33 continues

to flash until blower shuts off. Flame

rollout switch and BVSS requires manual

NO

YES

Do the main burners ignite?

reset. Check for:

- Dirty filter or restricted duct system.

- Defective blower motor or capacitor.

- Loose blower wheel.

- Defective switch or connections.

YES

NO

Do the main burners stay on?

(flame rollout switch open).

- Restricted vent.

- Inadequate combustion air supply

- Proper vent sizing.

- Excessive wind.

NO

YES

Repeat call for heat and check flame sensor

current during trial for ignition period. Is the

DC microamps below 0.5?

Clean flame sensor with fine steel wool and

recheck current. Nominal current is 4.0 to

6.0 microamps.

NO

is not sensed during the trial for ignition

period, the control will repeat the ignition

sequence 3 more times before lockout

#14 occurs. If flame signal is lost during

the blower on-delay period, blower will

come on for the selected blower off-delay.

Check the following items first before

34 IGNITION PROVING FAILURE – If flame

NO

Is current near typical value?

to furnace sheet metal.

proceeding to the next step.

- Gas valve turned off.

- Green/Yellow wire MUST be connected

- Flame sensor must not be grounded.

- Manual shut-off valve.

NO

YES

YES

Will main burners ignite and stay on?

YES

To determine whether the problem is in

the gas valve, igniter, or flame sensor

the system can be operated in the

component test mode to check the igniter.

First remove the R thermostat connection

from the control and initiate the

Fixed.

component test sequence. Does the

igniter glow orange/white by the end of

the 15 second warm-up period?

Fig. 63 -- Troubleshooting Guide 2--Speed

* Blocked vent shutoff switch used in Chimney Adapter Kit

are erased after 72 hours. On RED LED

boards stored status codes can also be

erased whenever power (115V or 24V)

is interrupted. Run system through a

low-heat, high-heat, or cooling cycle to

check system.

(115V OR 24V) – Normal operation.

Blower runs for the selected blower off-

11 NO PREVIOUS CODE – Stored codes

12 BLOWER ON AFTER POWER UP –

delay, if unit is powered up during a call

for heat (R-W/W1 closed) or when (R-

W/W1 opens) during the blower on-delay

period.

occurs if the limit, draft safeguard, flame

rollout, or blocked vent switch* (if used)

is open longer than 3 minutes. Control will

auto-reset after 3 hours. See code 33.

13 LIMIT CIRCUIT LOCKOUT – Lockout

ignite gas and prove flame in 4 attempts.

14 IGNITION LOCKOUT – System failed to

Control will auto-reset after 3 hours. See

status code 34.

control.

power and wait 5 minutes to retry.

Check for:

- Stuck closed gas valve relay on

- Miswire or short to gas valve wire.

Flame is proved while gas valve is de-

energized. Inducer will run until fault is

cleared. Check for:

- Stuck open or leaky gas valve.

Check for:

- Obstructed pressure tube.

- Pressure switch stuck closed.

21 GAS HEATING LOCKOUT – Tur n off

22 ABNORMAL FLAME-PROVING SIGNAL

23 PRESSURE SWITCH DID NOT OPEN

(24V) wiring including thermostat

OPEN Check for:

- Short circuit in secondary voltage

24 SECONDARY VOLTAGE FUSE IS

leads. Disconnect thermostat leads

to isolate short circuit.

RELAY DID NOT CLOSE OR

31 HIGH-HEAT PRESSURE SWITCH OR

REOPENED - Check for:

- Control relay may be defective.

- Gas valve is miswired.

- See status code 32.

56

57

E2007 B ryant Heating & Cooling Systems 7310 W. Mo rris St. Indianapolis, IN 46231 Printed in U.S.A. Edition Date: 02/07

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.

58

Catalog No. II312A--- 4 5 --- 8

Replaces: II312A--- 45--- 7