Lennox O23Q2-70, O23Q3-70, O23Q2-90, O23Q3-90, O23Q3-105 Installation Instructions Manual

504,626M

*P504626M*

03/10

*2P0310*

Page 1

E 2002 Lennox Industries Inc.

Dallas, Texas, USA

RETAIN THESE INSTRUCTIONS

FOR FUTURE REFERENCE

WARNING

Do not store or use gasoline or other flammable va­pors and liquids in the vicinity of this or any other ap­pliance.

WARNING

Improper installation, adjustment, alteration, ser­vice, or maintenance can cause injury or property
damage. Refer to this manual. For assistance or
additional information, consult a licensed profes­sional installer, or equivalent, or service agency.

INSTALLATION
INSTRUCTIONS

O23 SERIES UNITS

OIL UNITS

504,626M
38152A059
03/2010

Supersedes 01/2004

Table of Contents

General 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Shipping & Packing 1. . . . . . . . . . . . . . . . . . . . . . . . . .

O23 Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . .

O23 Start−Up & Performance Check List 2. . . . . . . .

O23 Unit Parts Arrangement 3. . . . . . . . . . . . . . . . . . . . .

O23 Oil Burner Parts Arrangement 3. . . . . . . . . . . . . . . .

Requirements 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Locate & Level the Unit 5. . . . . . . . . . . . . . . . . . . . . . .

Unit Adjustments 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Venting 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Flue Connections 10. . . . . . . . . . . . . . . . . . . . . . . . . . .

Supply & Return Air Plenums 11. . . . . . . . . . . . . . . . .

Oil Supply Line & Filter Connections 12. . . . . . . . . . .

Leak Check 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Electrical Wiring 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Unit Start-Up & Adjustments 16. . . . . . . . . . . . . . . . . .

Service 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Troubleshooting 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CAUTION

When venting this appliance, keep vent terminal free
of snow, ice and debris.

General

These instructions are intended as a general guide and do
not supersede local codes in any way. Only licensed pro­fessional technicians, or equivalent, can install and service
the Lennox Elite

®

Series O23 oil furnaces. In Canada, refer
to CSA B139 for recommended installation procedures.
Consult authorities who have jurisdiction before installa­tion.

CAUTION

Never burn garbage or paper in the heating system.
Never leave papers near or around the unit.

Shipping & Packing List

1− Assembled oil furnace
1− Barometric draft control
1− Side exhaust pipe collar
1− Direct intake collar (AFII burner units only)
Check the components for shipping damage. If you find

any damage, immediately contact the last carrier.

Litho U.S.A.

Page 2

O23 Unit Dimensions − Inches (mm)

SUPPLY

AIR

OPENING

FLUE

CONNECTION

(On Heat

Exchanger)

AIR FLOW

ELECTRICAL INLET

(Right Side Only)

OIL PIPING INLET

(Left Side Only)

RETURN AIR

OPENING

(Either Side)

TOP VIEW

SIDE VIEW FRONT VIEW

22

(559)

14

(356)

2 (51)

1-1/2

(38)

23-1/2

(597)

54

(1372)

1-1/2

(38)

3/4

(19)

AB

C

D

3/4

(19)

22

(559)

RETURN AIR

E

RETURN AIR

1-1/4

(32)

TOP FLUE

OUTLET

SIDE

FLUE OUTLET

CENTERING HOLE

(Field Fabricate

Either Side)

OPT. OUTDOOR

COMBUSTION

AIR INLET

CENTERING HOLE

(Field Fabricate

Right Side only)

Model No. A B C D E

O23Q2/3-70/90
O23Q3/4-105/120

in. 19-1/2 30-5/8 18 19-5/8 16

mm 495 778 457 498 406

O23Q5-140/154

in. 22-1/2 33-1/8 21 22-1/8 18

mm 572 841 533 562 457

O23 Start−Up & Performance Check List

Filter Clean & Secure?

Supply Voltage

Electrical Connections Tight?

Job Name

Job Location
Installer
Unit Model No.

Oil Pump Pressure [recommended min. 100 psig for −70;

min. 140 psig for all other units )]

Job No.

City

City

Serial No.

Date

State

Serviceman

Draft Reading (recommended .03−.04 inches w.c.)

Flue Connections Tight?

HEATING SECTION

THERMOSTAT

Calibrated? Heat Anticipator Properly Set? Level?

Blower Motor Amps

Blower Motor H.P.

Blower Motor Lubrication O.K.?

Piping Connections Tight?

Vent Clear?

State

Temperature RiseFan Control Cutout

Fan Control Setting (maximum 130_ F)

Burner Model No.

Serial Number

All Valves Open?

PROPER DRAFT

% CO2 (recommended 12%)

(55_C)

Page 3

O23 Unit Parts Arrangement

Figure 1

clean-out port

limit switch

control box

with fan control board

Beckettr

AFII burner

indoor blower

capacitor

blower motor

observation

port

clean−out port

flue opening

heat exchanger

combustion air intake

O23 Oil Burner Parts Arrangement

Figure 2

FB−HEAD

HEAD

INSULATOR

CLIP

RETAINING

1/4" HEX

HEAD SCREW

FB HEADS

ASSY FOR

AIR TUBE

ASSY.

ELECTRODE HEAD

NOZZLE LINE

PEDESTAL

ADAPTER

NOZZLE

AIR SCOOP

INLET

WHEEL

BLOWER

FLANGE

GASKET

MOTOR

4X4

BOX

IGNITOR

DOOR GASKET

REAR ACCESS

COUPLING

FUEL PUMP

PLATE

ESCUTCHEON

NUT

SPLINED

DOOR ASSY

REAR ACCESS

ASSY

HOUSING

MAIN

SCREWS

AIR TUBE

FLANGE

ASSY

ELECTRODE

6

5

4

3

7

0

8

ELECTRONIC IGNITION

TRANSFORMER

PRIMARY

CONTROL

AIR
ADJ.
DIAL

CONNECTOR

TUBE

PREMOUNTED OIL−DELAY VALVE

Page 4

Requirements

WARNING

Product contains fiberglass wool.

Disturbing the insulation in this product during
installation, maintenance, or repair will expose you
to fiberglass wool dust. Breathing this may cause
lung cancer. (Fiberglass wool is known to the State
of California to cause cancer.)

Fiberglass wool may also cause respiratory, skin,
and eye irritation.

To reduce exposure to this substance or for further
information, consult material safety data sheets
available from address shown below, or contact your
supervisor.

Lennox Industries Inc.

P.O. Box 799900
Dallas, TX 75379−9900

WARNING

Improper installation, adjustment, alteration, service
or maintenance can cause property damage, person­al injury or loss of life. Installation and service must
be performed by a qualified installer or service
agency.

Installation of Lennox oil−fired furnaces must conform with
the National Fire Protection Association Standard for the
Installation of Oil Burning Equipment, NFPA No. 31, the
National Electrical Code, ANSI/NFPA No.70 (in the
U.S.A.), CSA Standard CAN/CSA−B139 (in Canada),
Installation Code for Oil Burning Equipment, the Canadian
Electrical Code Part1, CSA 22.1 (Canada), the recommen­dations of the National Environmental Systems Contrac­tors Association and any state or provincial laws or local or­dinances. Authorities having jurisdiction should be
consulted before installation. Such applicable regulations
or requirements take precedence over general instructions
in this manual.

Chimneys and chimney connectors must be of the type and
construction outlined in section 160 of NFPA No. 31.

Air for combustion and ventilation must conform to stan­dards outlined in section 140 of NFPA No. 31 or, in Canada,
CSA Standard B139. When installing O23 units in confined
spaces such as utility rooms, two combustion air openings
are required. Dimensions of combustion air openings are
shown in table 1. One opening shall be below burner level
and the other opening shall be no more than 6"(152 mm)
from the room’s ceiling.

IMPORTANT

An opening to the outside for combustion air is
strongly recommended, especially in new homes.
Refer to table 2 or the unit rating plate for specific
combustion air opening dimensions.

The combustion air opening should provide a minimum
free area one-half square inch per 1,000 Btu per hour input.
This combustion air should be brought into the area con­taining the furnace below the level of the furnace burner.

Table 1

Combustion Air Opening Dimensions

Model No.

Combustion Air Opening

Dimensions (2 required)

O23−70/105/120 10" X 20" (254 mm X 508 mm)

O23−140/154 11" X 22" (279 mm X 559 mm)

This unit is approved for use on combustible flooring and
for clearances to combustible material as listed on unit rat­ing plate and in table 2. Unit service and accessibility clear­ances take precedence over fire protection clearances.

Table 2

Installation Clearances inches (mm)

Clearances

70/105/120 140/154

top of plenum and duct 2 (51) 2 (51)

plenum sides 3 (76) 3 (76)

sides 0 (0) 0 (0)

rear 0 (0) 0 (0)

front 4 (120) 4 (120)

flue pipe measured from

above

6 (152) 6 (152)

flue pipe measured vertical 6 (152) 6 (152)

NOTE − Service access clearance must be maintained.

*Minimum clearance shown for flue pipe may be reduced by using special
protection as provided by local building codes and the National Fire
Protection Association Standards.

Unit must be adjusted to obtain a temperature rise in the
range listed in table 6 in the Start-Up section of this manual.

When installed, furnace must be electrically grounded in
accordance with local codes or, in the absence of local
codes, with the current National Electric Code, ANSI/NFPA
No. 70, or Canadian Electric Code (CEC) if an external
electrical source is utilized.

Field wiring connection with unit must meet or exceed
specifications of type T wire and withstand a 63_F (17_C)
temperature rise.

Page 5

When furnace is used in conjunction with cooling units, it
shall be installed in parallel with, or on the upstream side of,
cooling units to avoid condensation in the heating element.
With a parallel flow arrangement, a damper (or other
means to control the flow of air) shall be adequate to pre­vent chilled air from entering the furnace and, if manually
operated, must be equipped with means to prevent opera­tion of either unit, unless damper is in the full heat" or cool"
position.

Locate & Level the Unit

1 − Set the unit in desired location keeping in mind the

clearances listed in table 2. Also keep in mind oil sup­ply connections, electrical supply, flue connections
and sufficient clearance for installing and servicing
unit.

2 − Level the unit from side to side and from front to rear. If

the furnace is not level, place fireproof wedges or
shims between the low side of the furnace and the
floor. Make sure the weight of the furnace is distributed
evenly on all four corners. Strain on sides of cabinet
causing cracking and popping noises may occur if
weight of furnace is not evenly distributed.

Unit Adjustments

Neither the nozzle setting nor the air adjustments are facto­ry set. The furnace is fire tested and the limit control is
checked to make sure it functions properly; no factory set­tings are made. During installation, the furnace must be
set up." The installing dealer/contractor must have and
use proper test equipment in order to correctly set up the oil
furnace. Proper testing equipment is required to ensure
correct operation of the unit. The use of test equipment is
now more critical than ever due to tighter tolerances need­ed to keep the furnace operating efficiently.
Among the test equipment for an oil furnace, the proper
combustion test kit should contain the following:

D Draft gauge
D CO

2

or O2 analyzer

D Smoke tester
D Pressure gauge
D High temperature thermometer
D Beckett T−500 gauge
D Oil vacuum gauge
D Knowledge of proper test equipment operation

CAUTION

Improper nozzle and/or air adjustment of this unit
may result in sooting problems. Refer to the follow­ing section for correct adjustment procedures.

Adjusting the Nozzle

Proper adjustment of the nozzle assembly is critical be­cause alignment may have changed during shipping. Be­fore the furnace and oil lines are installed, the nozzle as­sembly must be checked. To check the nozzle assembly,
remove the entire burner assembly (not just the nozzle)
from the furnace. The lower firing nozzle is factory
installed. This should be verified by the installer. Inspect
the spark transformer leads also to ensure they are still at­tached to the electrodes.

The burner assembly is attached to the vestibule panel by
three nuts. Slots are provided in the mounting flange for re­moving the burner assembly from the vestibule. By loosen­ing the nuts and by turning the whole burner assembly
counterclockwise (figure 3), the entire burner assembly will
come out of the furnace. There is adequate wire to remove
the burner without disconnecting wires. Once removed,
turn the burner around in the vest panel area.

Figure 3

O23 Series Burner Removal

Loosen three nuts which at-

tach burner to vest panel.

Rotate burner counterclockwise on

slots then pull toward you.

To correctly adjust the nozzle, use a Beckett #T−500 gauge

Insert the small end of the gauge into the end of the cone
and measure from the flat of the end cone to the tip of the
nozzle. When nozzle depth is correct, the tip of the nozzle
should just touch the end of the gauge. Refer to the illustra­tion sheet provided with the gauge. Note that the scale side
of the gauge is not used for this purpose. Make corrections
by sliding the nozzle assembly forward or backward within
the blast tube (figure 4). At the same time, check the nozzle
alignment.

Page 6

To check nozzle alignment, again insert the small end into
the end cone and measure the nozzle and electrode align­ment against the center lines marked on the gauge (again
refer to enclosed illustration sheet). If the nozzle is not cen­tered, but found to be too far left or right, a new nozzle as­sembly will need to be ordered. Do not attempt to adjust by
bending the 90 degree elbow in the oil line.

Figure 4

Beckett Oil Burner Nozzle Adjustment

TO ADJUST NOZZLE:

Burner must be removed from

furnace for this procedure.

GAUGE

1−Loosen screw.
2−Slide entire nozzle/electrode assembly back and forth until
nozzle just touches gauge.

1

2

Venting

WARNING

Combustion air openings in front of the furnace must
be kept free of obstructions. Any obstruction will
cause improper burner operation and may result in
a fire hazard.

WARNING

The barometric damper shall be in the same atmo­spheric pressure zone as the combustion air inlet to
the furnace. Deviation from this practice will cause
improper burner operation and may result in a fire
hazard.

CAUTION

Do not store combustible materials near the furnace
or supply air ducts. The material (such as paint, mo­tor oil, gasoline, paint thinner, etc.) may ignite by
spontaneous combustion creating a fire hazard.

WARNING

This furnace is certified for use with type L" vent.
B" vent must not be used with oil furnaces.

NOTE − Oil burning equipment may be vented into an ap­proved masonry chimney or type L vent. (Type L vent is
similar in construction to type B gas vent except it carries a

higher temperature rating and is constructed with an inner
liner of stainless steel rather than aluminum).

Prior to installation of unit, make a thorough inspection of
the chimney to determine whether repairs are necessary.
Make sure the chimney is properly constructed and sized
according to the requirements of the National Fire Protec­tion Association. The smallest dimensions of the chimney
should be at least equal to the diameter of the furnace vent
connector. Make sure the chimney will produce a steady
draft sufficient to remove all the products of combustion
from the furnace. A draft of at least .04" w.c. (9.9 Pa) is re­quired during burner operation.

1 − Local building codes may have more stringent installa-

tion requirements and should be consulted before
installation of unit.

2 − The vent connector should be as short as possible to

do the job.

3 − The vent connector should not be smaller than the out-

let diameter of the vent outlet of the furnace.

4 − Pipe should be at least 24 gauge galvanized.

5 − Single wall vent pipe should not run outside or through

any unconditioned space.

6 − Chimney should extend 3 feet (0.9 m) above highest

point where the vent passes through the roof, and 2
feet (0.6 m) higher than any portion of a building within
a horizontal distance of 10 feet (3 m).

7 − The vent must not pass through a floor or ceiling.

Clearances to single wall vent pipe should be no less
than 6" (152 mm); more if local codes require it.

8 − The vent may pass through a wall where provisions

have been made for a thimble as specified in the Stan­dards of the National Board of Fire Underwriters. See
figure 5.

WALL THIMBLE

FIGURE 5

THIMBLE

VENT PIPE

COMBUSTIBLE

WALL

9 − The vent pipe should slope upward toward the chim-

ney on horizontal run at least 1/4 inch (6 mm) to the
foot (0.3 m) and should be supported by something
other than the furnace, such as isolation hangers. See
figure 6.

Page 7

MASONRY CHIMNEY

BAROMETRIC

CONTROL*
(IN EITHER

LOCATION)

CLEAN OUT

CLEAN OUT

LINER

MASON-

RY

CHIMNEY

Figure 6

*Barometric control may be installed in either vertical or hori­zontal section of flue pipe within 18" of flue outlet of furnace.

10− Extend the vent pipe into the chimney so that it is flush

with the inside of the vent liner. Seal the joint between
the pipe and the liner.

11− The furnace shall be connected to a factory built chim-

ney or vent complying with a recognized standard, or
masonry or concrete chimney lined with a lining mate­rial acceptable to the authority having jurisdiction.

12− When two or more appliances vent into a common

vent, the area of the common vent should not be less
than the area of the largest vent or vent connection
plus 50% of the area of the additional vent or vent con­nection. Chimney must be able to sufficiently vent all
appliances operating at the same time.

13− The vent pipe shall not be connected to a chimney

vent serving a solid fuel appliance or any mechanical
draft system.

14− All unused chimney openings should be closed.

15− All vent pipe run through unconditioned areas or out-

side shall be constructed of factory built chimney sec­tions. See figure 7.

16− Where condensation of vent gas is apparent, the vent

should be repaired or replaced. Accumulation of con­densation in the vent is unacceptable.

17− Vent connectors serving this appliance shall not be

connected into any portion of mechanical draft sys­tems operating under positive pressure.

18− Keep the area around the vent terminal free of snow,

ice and debris.

NOTE − If vent pipe needs to exit from side of cabinet,
use the pilot hole (located on either side of the unit) to
cut a 6" (152 mm) round hole. Attach finishing plate
(provided) with four sheet metal screws to cover rough
edges.

FACTORY−BUILT CHIMNEY

BAROMETRIC

CONTROL*
(IN EITHER

LOCATION)

DRAIN FOR

CONDENSATE

FACTORY

BUILT

CHIMNEY

Figure 7

*Barometric control may be installed in either vertical or hori­zontal section of flue pipe within 18" of flue outlet of furnace.

Combustion and Ventilation Air
(Confined and Unconfined Spaces)

In the past, there was no problem in bringing in sufficient
amounts of outdoor air for combustion − infiltration provided
all the air that was needed and then some. In today’s
homes built with energy conservation in mind, tight
construction practices make it necessary to bring in air
from outside for combustion. Consideration must also be
given to the use of exhaust fans, appliance vents, chim­neys and fireplaces because they force additional air that
could be used for combustion out of the house. Unless out­side air is brought into the home for combustion, negative
pressure (pressure outside is greater than inside pressure)
will build to the point that a down draft can occur in the fur­nace vent pipe or chimney. Combustion gases enter the liv­ing space creating a potentially dangerous situation.

The importance of the previous paragraph cannot be over­stated. Users may inadvertently block fresh air intakes af­ter installation.

In the absence of local codes concerning air for combus­tion and ventilation, the following section outlines guide­lines and recommends procedures for operating oil fur­naces in a manner that ensures efficient and safe
operation. Special consideration must be given to combus­tion air needs as well as requirements for exhaust vents
and oil piping.

Page 8

Combustion Air Requirements

CAUTION

Insufficient combustion air can cause headaches,
nausea, dizziness or asphyxiation. It will also cause
excess water in the heat exchanger resulting in rust­ing and premature heat exchanger failure. It can also
cause property damage.

All oil-fired appliances require air to be used for the com­bustion process. If sufficient amounts of combustion air are
not available, the furnace or other appliance will operate in
an inefficient and unsafe manner. Enough air must be pro­vided to meet the needs of all fuel-burning appliances, as
well as appliances such as exhaust fans which force air out
of the home. When fireplaces, exhaust fans, or clothes dry­ers are used at the same time as the furnace, much more
air is required to ensure proper combustion and to prevent
a down-draft situation. Insufficient amounts of air also
cause incomplete combustion which can result in sooting.
Requirements for providing air for combustion and ventila­tion depend largely on whether the furnace is installed in an
unconfined or confined space.

Unconfined Space

An unconfined space is an area such as a basement or
large equipment room with a volume greater than 50 cubic
feet (1.4 cubic meters) per 1,000 Btu (293 W) per hour of
the combined input rating of all appliances installed in that
space. This space also includes adjacent rooms which are
not separated by a door. Though an area may appear to be
unconfined, it might be necessary to bring in outdoor air for
combustion if the structure does not provide enough air by
infiltration. If the furnace is located in a building of tight
construction with weather stripping and caulking around
the windows and doors, follow the procedures outlined for
using air from the outside for combustion and ventilation.

Confined Space

A confined space is an area with volume less than 50 cubic
feet (1.4 cubic meters) per 1,000 Btu (293 W) per hour of
the combined input rating of all appliances installed in that
space. This definition includes furnace closets or small
equipment rooms.

When the furnace is installed so that supply ducts carry air
circulated by the furnace to areas outside the space con­taining the furnace, the return air must be handled by ducts
which are sealed to the furnace casing and which terminate
outside the space containing the furnace. This is especially
important when the furnace is mounted on a platform in a
confined space such as a closet or small equipment room.

Even a small leak around the base of the unit at the platform
or at the return air duct connection can cause a potentially
dangerous negative pressure condition. Air for combustion
and ventilation can be brought into the confined space ei­ther from inside the building or from outside.

Air from an Adjacent Space

If the confined space housing the furnace adjoins space
categorized as unconfined, air can be brought in by provid­ing two permanent openings between the two spaces.
Each opening must have a minimum free area of 1 square
inch

(6.4 square centimeters) per 1,000 Btu (293 W) per

hour of the total input rating of all fuel-fired equipment in the
confined space. Each opening must be at least 100 square
inches (614.5 square centimeters). One opening shall be
within 12" (305 mm) of the top of the enclosure and one
opening within 12" (305 mm) of the bottom (See figure 8).

EQUIPMENT IN CONFINED SPACE

ALL AIR FROM INSIDE

CHIMNEY OR

OIL VENT

WATER

HEATER

OPENINGS

(To Adjacent Room)

FIGURE 8

NOTE−Each opening shall have a free area of at least 1 square inch
(6.4 square centimeters) per 1,000 Btu (293 W) per hour of the total
input rating of all equipment in the enclosure, but not less than 100
square inches

(614.5 square centimeters).

OIL

FURNACE

Air from Outside

If air from outside is brought in for combustion and ventila­tion, the confined space shall be provided with two perma­nent openings. One opening shall be within 12" (305 mm)
of the top of the enclosure and one within 12" (305 mm) of
the bottom. These openings must communicate directly or
by ducts with the outdoors or spaces (crawl or attic) that
freely communicate with the outdoors or indirectly through
vertical ducts. Each opening shall have a minimum free
area of 1 square inch (6.4 square centimeters) per 4,000
Btu (1172 W) per hour of total input rating of all equipment
in the enclosure (See figures 9 and 11). When communi-

Page 9

cating with the outdoors through horizontal ducts, each
opening shall have a minimum free area of 1 square inch
(6.4 square centimeters) per 2,000 Btu (586 W) per total in­put rating of all equipment in the enclosure (See figure 11).

EQUIPMENT IN CONFINED SPACE

ALL AIR FROM OUTSIDE

(Inlet Air from Crawl Space and

Outlet Air to Ventilated Attic)

NOTE − The inlet and outlet air openings shall each have a free area
of at least one square inch (6.4 square centimeters) per 4,000 Btu
(1172 W) per hour of the total input rating of all equipment in the en­closure.

VENTILATION LOUVERS

(Each end of attic)

OUTLET

AIR

WATER

HEATER

INLET

AIR

CHIMNEY

OR OIL

VENT

VENTILATION

LOUVERS

(For unheated

crawl space)

FIGURE 9

OIL

FURNACE

EQUIPMENT IN CONFINED SPACE

ALL AIR FROM OUTSIDE

(All Air Through Ventilated Attic)

NOTE−The inlet and outlet air openings shall each have a free area of
at least one square inch (6.4 square centimeters) per 4,000 Btu (1172
W) per hour of the total input rating of all equipment in the enclosure.

CHIMNEY

OR OIL

VENT

WATER

HEATER

OUTLET

AIR

VENTILATION LOUVERS

(Each end of attic)

INLET AIR

(Ends 12" above

bottom)

FIGURE 10

OIL

FURNACE

EQUIPMENT IN CONFINED SPACE

ALL AIR FROM OUTSIDE

OUTLET AIR

INLET AIR

WATER

HEATER

CHIMNEY

OR OIL

VENT

FIGURE 11

NOTE − Each air duct opening shall have a free area of at least one
square inch (6.4 square centimeters) per 2,000 Btu (586 W) per hour
of the total input rating of all equipment in the enclosure. If the equip­ment room is located against an outside wall and the air openings
communicate directly with the outdoors, each opening shall have a
free area of at least one square inch (6.4 square centimeters) per
4,000 Btu (1172 W) per hour of the total input rating of all other
equipment in the enclosure.

OIL

FURNACE

When ducts are used, they shall be of the same cross−sec­tional area as the free area of the openings to which they
connect. The minimum dimension of rectangular air ducts
shall be no less than 3" (76 mm). In calculating free area,
the blocking effect of louvers, grilles, or screens must be
considered. If the design and free area of protective cover­ing is not known for calculating the size opening required, it
may be assumed that wood louvers will have 20 to 25 per­cent free area and metal louvers and grilles will have 60 to
75 percent free area. Louvers and grilles must be fixed in
the open position or interlocked with the equipment so that
they are opened automatically during equipment opera­tion.

Direct Connection of Outdoor Air for Combustion

The Beckett AFII burner was designed to allow for direct air
intake piping (4" [102 mm]). The maximum equivalent
length of pipe is 70 feet (21.3 m). A 90_ elbow equals 6feet
(1.8 m). The enclosed intake pipe ring may be used to facili­tate direct air intake to the burner through the right side of
the cabinet. The AFG burner requires a special kit for direct
air intake. Refer to kit instructions.

To convert the AFII burner from confined space to outside
combustion air, simply remove the three screws attaching
the inlet air scoop to the burner and insert 4" (102 mm) di­rect air intake piping.

The use of a barometric relief placed in the intake pipe is
recommended when outdoor combustion air is directly
connected to the burner. This will allow confined space air
to be used as combustion air in the event that the opening
to the outdoor air becomes blocked. Using a barometric re­lief in the intake will reduce the chance of sooting.

Page 10

CAUTION

DO NOT USE a barometric draft relief in exhaust vent
pipe if outdoor combustion air is connected directly
to the burner.

Removal of Unit from Common Venting System

In the event that an existing furnace is removed from a
venting system commonly run with separate appliances,
the venting system is likely to be too large to properly vent
the remaining attached appliances. The following test
should be conducted while each appliance is in operation
and the other appliances not in operation remain con­nected to the common venting system. If venting system
has been installed improperly, the system must be cor­rected as outlined in the previous section.

1 − Seal any unused openings in the common venting

system.

2 − Visually inspect venting system for proper size and

horizontal pitch and determine there is no blockage or
restriction, leakage, corrosion or other deficiencies
which could cause an unsafe condition.

3 − Insofar as is practical, close all building doors and win-

dows and all doors between the space in which the ap­pliances remaining connected to the common venting
system are located and other spaces of the building.
Turn on clothes dryers and any appliances not con­nected to the common venting system. Turn on any
exhaust fans, such as range hoods and bathroom ex­hausts, so they will operate at maximum speed. Do not
operate a summer exhaust fan. Close fireplace damp­ers.

4 − Following the lighting instruction on the unit, place the

appliance being inspected in operation. Adjust ther­mostat so appliance will operate continuously.

5 − Test for spillage using a draft gauge.

6 − After it has been determined that each appliance re-

maining connected to the common venting system
properly vents when tested as outlined above, return
doors, windows, exhaust fans, fireplace dampers and
any other fuel burning appliance to their previous con­dition of use.

7 − If improper venting is observed during any of the

above tests, the common venting system must be cor­rected.

Horizontal Venting

The O23 is approved for horizontal venting with the follow­ing mechanical vent systems:
Tjernlund (sideshot) #SS1C (Cat. #35E08) or Field Con­trols #SWG−5 (Cat. #35P08) with the CK−61 (Cat. #18N28)
control kit. Refer to the manufacturers’ installation instruc­tions for proper installation procedures and service parts
information.

Do not use the same vent with any other appliance
when using a sidewall vent system.

Maximum permissible vent length is 70 equivalent feet.
Minimum length is 15 equivalent feet. Calculate the equiva­lent vent pipe footage from the furnace to the mechanical
vent system (Tjernlund or Field Controls) by adding the
straight vent pipe length and the equivalent elbow lengths
together.

Locate the barometric draft control within 18 inches of the
furnace flue outlet. See figure 12 for barometric draft con­trol location.

HORIZONTAL VENTING

barometric

control*

horizontal venting

control

Figure 12

*Barometric control must

be installed in the hori-

zontal venting system and

located within 18" of flue

outlet of furnace.

Flue Connections

IMPORTANT

When flue pipe is installed at less than minimum
clearance listed in table 2, radiation shields must be
installed. See figure 13.

Page 11

1"

(25 mm)

min

Figure 13

combustible

material

Radiation Shield Installation

O23 unit

(top)

O23 UNIT

(front)

radiation

shields

flue

pipe

unit

cabinet

NOTE 1−Radiation shields must be constructed of 24 gauge sheet
metal minimum.

NOTE 2−Radiation shields required when A is less than 9" (229 mm).

NOTE 3−Radiation shields should extend from the top of the unit to
the top of the flue pipe.

noncombustible

spacers

radiation shields

(see note 1)

See note 2

See note 3

7"

(178 mm)

min

12"

(305 mm)

min

B

A

A

Use 24 gauge or heavier galvanized smoke pipe and fit­tings to connect the furnace to the vent. Connect flue pipe
to chimney using the least number of elbows and angles
possible. Flue pipe or vent connector must be inserted into
but not beyond the outside wall of the chimney flue. No re­duction in diameter of flue pipe is acceptable. It is best to
have flue pipe as short and direct as possible. Where two or
more appliances vent into a common flue, the area of the
common flue should be at least equal to the area of the larg-

est flue or vent connector, plus 50% of the area of any addi­tional flues or vent connectors. Install a barometric draft
control (provided) and flue pipe according to instructions
packed with control.

Inspect flue pipe annually. Clean soot or ash from flue pipe,
if necessary. If pipe is rusted, replace.

Install draft control at least 12 inches beyond the furnace. If
there is no space to install the draft control in the flue pipe it
may be installed in the vent above the flue pipe. Follow the
instructions packed with the draft control.

Alternate Side Flue Connections

The vent pipe may exit the top or sides of the cabinet. A
hole is provided in the top cap for top exit. For side exit, lo­cate the center hole punched in the side of the cabinet. See
unit dimensions on page 2. Using it as the center point, cut
a 6 inch (152 mm) round hole in the cabinet’s side. Install
the barometric draft control within 18 inches of the furnace
flue outlet.

Attach the provided finishing plate to cover rough edges.

Supply & Return Air Plenums

Secure return air plenum to unit using sheet metal screws.

NOTE − The following are suggested procedures that
should be followed when installing the supply air plenum.

1 − Use sealing strips of fiberglass.
2 − In all cases, the plenum should be secured to furnace

or evaporator cabinet with sheet metal screws.

3 − Install supply and return air ducts as desired.

Oil Supply Line Sizing

Ensure that the restrictions of the piping system, plus any
lift involved, do not exceed the capability of the oil pump.
Use the following guidelines when determining whether to
use a single−or two−stage oil pump.

One−Pipe System

When using a one−pipe system even with the oil tank that is
above the burner and a vacuum of 6" (152 mm) Hg or less,
a single−stage fuel pump with a supply line and no return
line should be adequate. See figure 14.

Page 12

Manual bleeding of the fuel pump is required on initial start
up. Failure to bleed air from the oil pump could result in an
air lock/oil starvation condition.

NOTE − As an extra precaution, cycle heating on and off ten
times after bleeding air from the oil pump. This will elimi­nate air in the gun assembly.

Figure 14

Oil Piping

air vent

fill

pipe

Oil

Tank

fuel

pump

Aux

Filter

Shut−off

Valve

8 ft (2.4 m)

Maximum

One Pipe Lift

One-Pipe System

To determine the correct tubing size for piping, refer to
table 3 .

Table 3

One−Pipe Oil Line Sizing

Line Length

Pipe Diameter (OD Tubing)

0−50’ (15 m) 3/8" (10 mm)

51−100’ (15 m) 1/2" (12 mm)

Two−Pipe System

When using a two−pipe system with the oil tank below the
level of the burner, use a single−stage fuel pump in lift con­ditions of up to 10 feet (3 m) and/or a vacuum of 10" (254
mm) Hg or less. See figure 15. Use a two−stage fuel pump
when lift exceeds 10 feet (3 m) and/or a vacuum of 10" (254
mm) Hg to 15" (381 mm) Hg. Both conditions require that
you use of a two−pipe system, which consists of a return
line that purges the fuel pump of air by returning it to the
tank. To determine the run and lift for piping, refer to table 4.

Use continuous lengths of heavy wall copper tubing or
steel pipe for oil supply pipe. Install oil supply pipe under
floor or near walls to protect it from damage. Avoid running
pipes along joists or reverberating surfaces. Always use
flare fittings. All fittings must be accessible. Do not use
compression fittings.

IMPORTANT

Both oil supply and return pipes must be submerged
in oil in the supply tank.

Figure 15

Oil Piping

fuel

pump

Aux

Filter

Return

pipe

Fill

Pipe

Air Vent

Oil

Tank

Inlet

Return

pipe

H

3"−4"

(76 mm −102 mm)

R

outside tank fuel pump above bottom of tank.

Two-Pipe System

Table 4

Two−Pipe Maximum Pipe Length (H + R)

Lift H"

3450 RPM − 3 GPH (11.4 LPH)

3/8" (10 mm) OD

Tubing

1/2" (12 mm) OD

Tubing

Single

Stage

Two

Stage

Single

Stage

Two

Stage

0’

(0.0 m)

84’

(25.6 m)

93’

(28.3 m)

100’

(30.5 m)

100’

(30.5 m)

2’

(0.6 m)

73’

(22.3 m)

85’

(25.9 m)

100’

(30.5 m)

100’

(30.5 m)

4’

(1.2 m)

63’

(19.2 m)

77’

(23.5 m)

100’

(30.5 m)

100’

(30.5 m)

6 ’

(1.8m)

52’

(15.8 m)

69’

(21.0 m)

100’

(30.5 m)

100’

(30.5 m)

8’

(2.4 m)

42’

(12.8 m)

60’

(18.3 m)

100’

(30.5 m)

100’

(30.5 m)

10’

(3.0 m)

31’

(9.4 m)

52’

(15.9 m)

100’

(30.5 m)

100’

(30.5 m)

12’

(3.7 m)

21’

(6.4 m)

44’

(13.4 m)

83’

(25.3 m)

100’

(30.5 m)

14’

(4.3 m)

−−−

36’

(11.0 m)

41’

(12.5 m)

100’

(30.5 m)

16’

(4.9 m)

−−−

27’

(8.2 m)

−−−

100’

(30.5 m)

18’

(5.5 m)

−−− −−− −−−

76’

(23.2 m)

Oil Supply Line & Filter Connections

One−Pipe Systems

CAUTION

Do not install the bypass plug into the pump on one−
pipe systems.

The burner is shipped with fuel pump set for one−pipe op­eration. For one−pipe systems, the oil supply pipe is con­nected to the inlet tap on the pump. A one−pipe system
should only be used where there is gravity oil flow to the
pump and the pipe is not run at any point above the oil level
in the tank.

Page 13

1 − Connect the inlet pipe to the pump inlet. Start the burn-

er.

2 − Set the primary burner control for continuous opera-

tion during purging.

3 − Turn the bleed valve one turn counterclockwise to

open.

4 − Bleed the unit until all air bubbles disappear.

NOTE − Hurried bleeding will prevent the unit from op­erating properly.

5 − Tighten the bleed valve securely.

Two−Pipe Systems

If the installation requires a two−pipe operation, install the
bypass plug included in the bag which is attached to the
pump. To convert the pump, install the bypass plug accord­ing to the provided pump instructions. Notice in the two­pipe system the return pipe must terminate in the tank 3"
(76 mm) to 4" (102 mm) above the supply inlet. Ensure the
return pipe terminates at the correct measurement or air
may escape into the system. This could result in loss of
prime.

NOTE− If using an outside tank in cold climates a number
one fuel or an oil treatment is strongly recommended.

1 − Remove 1/4" plug from return port.

2 − Insert bypass plug and tighten it. See figure 15.

3 − Attach the return and inlet pipes. Start the burner. Air

bleeding is automatic.

NOTE − If a faster bleed is necessary, open the bleed
valve.

4 − The return pipe must terminate 3" to 4" above the sup-

ply pipe inlet. See figure 15.

NOTE − If the return pipe does not terminate where it
should, air may enter the system, and prime may be
lost.

An oil filter is required for all models. Install filter inside
the building between the tank shut-off valve and the burner.
Locate filter close to burner for easy maintenance. Table 5
lists the filters for the O23 furnace.

Table 5

Installation Clearances inches (mm)

Oil Filters

Cat.

Number

10 micron filter (no mounting bracket) 81P89

10 micron filter (mounting bracket) 53P92

10 micron replacement cartridge for filter, 45 gph 53P93

Filter restriction indicator gauge 53P90

Consult burner manufacturer’s instructions packaged with
unit for further details concerning oil supply pipe connec­tions.

Leak Check

After oil piping is completed, carefully check all piping con­nections (factory and field) for oil leaks.

Oil Pipe Heater (Optional)

A heater for the oil pipe is available for applications that are
located in cold climates. The heater warms the oil pipe to
assist the initial start−up.

Electrical Wiring

All wiring must conform to the National Electric Code
(NEC), or Canadian Electric Code (CEC) and any local
codes. Refer to figure 16 for the terminal designations on
the fan control board.

1 − Refer to the appliance rating plate for proper fuse size.

2 − Install the room thermostat and make wire connections

to the fan control board. Avoid installing thermostat on
an outside wall or where it can be affected by radiant
heat. Set the adjustable heat anticipator on thermostat
according to the wiring diagram sticker provided on
unit.

3 − Install a separate fused disconnect switch near unit so

power can be shut off for servicing.

4 − Complete line voltage wiring from disconnect switch

near unit to make-up box.

NOTE − An equipment ground screw is provided. Refer
to unit wiring diagram and figures 17 or 18 for O23 se­ries units. Ground unit using a suitable ground wire.

5 − Any accessory rated up to 1 amp can be connected to

the accessory terminal. The accessory terminal is en­ergized when the blower is operating.

IMPORTANT

When an accessory is being used in a continuous fan
application which does not include the S68 ON/OFF
switch, the accessory must be wired between L1 and
N on the fan control board to ensure proper voltage.

Fan Control Board

thermostat

terminal strip

Figure 16

Page 14

Figure 17

Typical O23 Wiring Diagram

Page 15

Figure 18

Typical O23 Wiring Diagram

Page 16

Unit Start−Up & Adjustments

Before starting unit, make sure the oil tank is adequately
filled with clean No. 1 or No. 2 furnace oil.

NOTE − Water, rust or other contaminants in oil supply sys­tem will cause malfunction and failure of the internal parts
of the fuel pump.

CAUTION

Never burn garbage or paper in the heating system.
Never leave papers near or around the unit.

CAUTION

Blower door must be in place before start−up.

1 − Set thermostat for heating demand and turn on electri-

cal supply to unit.

2 − Check initial air adjustment. All units are equipped with

an air adjustment dial on the right side of the burner.
See burner parts arrangement illustration.

3 − Turn unit on. Place a can or container under the bleed

port located on the fuel pump. Loosen nut on bleed port
to release air and oil mixture from fuel line. Allow mix­ture to escape until a steady stream of oil is emitted
from the port. Drain at least 1/2 pint of oil from the
pump. Retighten the nut on bleed port. If lockout oc­curs, press reset button and continue with bleed proce­dure.

NOTE − A two−pipe fuel system will normally bleed itself
by forcing air back to the tank through the return line.
This type of bleeding procedure is not necessary.

4 − If burner fails to start, push reset button on primary

safety control and the burner motor reset button. See
part arrangement illustration.

CAUTION

Do not push the reset button on the primary control
more than one time.

5 − If the burner fails to light again, refer to the trouble-

shooting section in this manual.

A − Fuel Pump Pressure

Measure fuel pump pressure with unit off. Attach pressure
gauge to pump outlet. Turn unit on and check pressure and
compare to table 6. Adjust if necessary.

B − Temperature Rise

To measure temperature rise, place plenum thermometers
in warm air and return air plenums. Locate thermometer in
warm air plenum where thermometer will not see" the heat
exchanger to prevent it from picking up radiant heat. Set
thermostat to its highest setting to start unit. After plenum
thermometers have reached their highest and steadiest

readings, subtract the readings. The difference in tempera­tures in the supply and return air plenums should approxi­mate the temperature rise range listed in table 6 and the ap­pliance rating plate. If not, adjust the blower motor pulley to
adjust the blower speed.

Table 6

O23
Unit

nozzle size,

spray
angle,

& pattern

pump

PSIG

input

rating

BTU/HR

output

rating

BTU/HR

head temp

rise

F°

−70 .50GPH−80° A 100 70,000 57,000 FB0 60−70

−105 .65GPH−80° B 140 105,000 84,000 FB3 65−75

−120 .75GPH−80° B 140 119,000 105,000 FB3 70−80

−140 .85GPH−80° B 140 140,000 112,000 FB6 65−75

−154 1.0GPH−80° B 140 154,000 125,000 FB6 70−80

C − Limit Control

Limit Control − Do not adjust it from factory setting.

D − Fan Control

The fan on time of 30 seconds is not adjustable. Fan off
time (time that the blower operates after the heat demand
has been satisfied) can be adjusted by moving the delay
switches on the fan control board. Fan off time will affect
comfort and is adjustable to satisfy individual applications.
See figure 19. Set the heat fan off delay switches to either
60, 90, 120, or 150 seconds. The factory setting is 90 sec­onds.

150 sec

Figure 19

Fan Off Delay Switch Settings

120 sec90 sec60 sec

E − Burner Adjustment

The following instructions are essential to the proper op­eration of O23 series oil furnaces. To prevent sooting,
these instructions must be followed in sequence:

1 − Draft

This test should be taken at the breach between the outlet
of the vent connector and the barometric draft control. Gen­erally a 1/4" hole will need to be drilled for the draft gauge to
be inserted into the vent connector.
A minimum of 0.03 draft must be established without the
burner in operation. With the burner in operation, the draft
should be 0.04 to 0.05. This is VERY critical to the flame
retention head burners.

Oil furnace installations also require careful inspection to
make sure the chimney is in good shape and can accom­modate the products of combustion. The temperature in
the unconditioned space will also affect the draft if long vent
connectors are allowed to get too cold.

Page 17

2 − Overfire Draft

This test should be taken with the burner in operation. Re­move the screw from the center of the inspection port. In­sert your draft gauge into the hole.

A reading of the overfire draft should be 0.02 less than the
reading found in the vent connector. If a positive reading is
seen at this point, the combustion fan is pumping too much
air into the heat exchanger. Make the necessary adjust­ments at the air adjustment dial.

3 − Smoke Test

The smoke test should be taken at the hole drilled in step 1.

Using a smoke test gun adjust the air inlet shutter so that
you will have just a trace of smoke. Somewhere between a
0 and #1 smoke. This is the starting point. Do not stop here.

4 − CO

2

Test

Again, take this sample at the vent pipe. With the unit firing
at a trace of smoke, take a sample of the CO

2

.

From the results of this test, a window of operation" will be
determined. This window of operation establishes some
tolerance. The tolerance the installer builds in provides
room within the set-up for those things which might affect
combustion. Those things which might affect combustion
can then do so without causing the unit to start sooting/
smoking. Things which might affect combustion include a
nozzle going bad, draft that changes during different clima­tic conditions, dirty oil, dirt obstructing the air inlet, etc.

To build in a window of operation," set up the burner to be
2% less in CO

2

. For example, if you find a reading of 12%

CO

2

, adjust the air inlet shutter to increase the air and drop

the CO

2

to 10%.

5 − Retest the Smoke

With a drop in the CO

2

and increase in the air you should

see that the smoke has returned to 0.

6 − Retest the Overfire Draft

This test serves to confirm that you have not increased the
air too much. Again you do not want a positive pressure at
the test port. It should still be 0.02 less than the draft pres­sure reading taken at the breach. You may need to in­crease the stack draft by adjusting the barometric draft
control.

7 − Stack Temperature

Take a stack temperature reading in the vent pipe. Subtract
the room air temperature from the stack temperature. This
will give you the net stack temperature. Use the efficiency
charts provided in most CO

2

analyzers to determine fur-

nace efficiency.

Service

CAUTION

Do not tamper with unit controls. Call your qualified
service technician.

A − Servicing Filter

NOTE − Under no circumstances should the access panels
to the blower compartment be left off or left partially open.

Throw-Away Type Filters  Check filters monthly and re-

place when necessary to assure proper furnace operation.
Replace filters with like kind and size filters.

Reusable Type Filters  Filters should be checked month­ly and cleaned when necessary to assure proper furnace
operation.

B − Blower

Blower motor is prelubricated and sealed for extended op­eration. No further lubrication is required. Disconnect pow­er to unit before cleaning blower wheel for debris.

C − Flue Pipe Inspection

The flue pipe should be inspected annually by a qualified
service technician. Remove and clean any soot or ash
found in the flue pipe. Inspect pipe for holes or rusted
areas. If replacement is necessary, replace with the same
size and type as required by code. Inspect the flue draft
control device and replace if found defective.

D − Cleaning the Heat Exchanger

1 − Remove the vent pipe from the furnace.

2 − Remove the locking screws and the caps from the

clean out tubes. Remove flue access elbow.

3 − Using a long spiral wire brush, sweep down the outer

drum of the heat exchanger. Then using the hose at­tachment, vacuum out loose debris.

4 − Remove the locking screw and cap from the observa-

tion tube and with the spiral wire brush, reach upward
toward the rear of the heat exchanger to clean out the
crossover tube.

CAUTION

Do not attempt to clean the combustion chamber. It
can be easily damaged.

5 − Replace the clean out caps and flue access elbow.

Make sure locking screws are secure.

6 − Brush out and vacuum the vent outlet area of the outer

drum and replace vent pipe.

7 − Clean around the burner, blower deck and vestibule

area.

NOTE − A heat exchanger clean-out kit ABRSH380
(35K09) is available from Lennox.

Page 18

Troubleshooting

Burner failure or improper operation can result from a num­ber of different causes.
Often the cause can be pinpointed by observing the differ­ent types of failure or by the process of elimination. The fol-

lowing troubleshooting charts list some failures, causes
and a sequence of steps to isolate the point of failure.
Check the simplest and most obvious items before prog­ressing to other items.

Troubleshooting: Fan board operating sequence

Action System Response

Thermostat calls for heat.
(W terminal is energized.)

ST9103A closes oil primary control T−T connections.

Ignition system and oil primary control start the furnace. Oil flows as long as oil primary
control senses flame.

Burner motor is energized and heat fan on delay timing begins. When timing is complete,
the circulating fan is energized at heat speed and warm air is delivered to the controlled
space.

Thermostat ends call for heat.
(W terminal is de−energized.)

Oil primary control is de−energized, terminating the burner cycle.

Heat fan off delay timing begins. When timing is complete, the circulating fan is de−ener­gized.

ST9103A returns to standby mode (oil primary control and circulating fan are off).

Burner fails to light. Oil primary control locks out within lockout timing (timing depends on oil primary control).

Burner motor is de−energized.

If heat fan has started, it continues through the selected delay off period.

Established flame fails. Burner motor is de−energized and oil primary control goes into recycle mode.

If selected heat fan off delay is longer than the recycle delay timing, the heat fan contin­ues to run through the next trial for ignition.

Thermostat begins call for cool.
(G and Y terminals are energized.)

Circulating fan is energized at the cool speed.

Cooling compressor turns on immediately.

Thermostat ends call for cool.
(G and Y terminals are de−energized.)

Circulating fan and cooling compressor turn off immediately.

Thermostat begins call for fan.
(G terminal is energized.)

Circulating fan is energized immediately at cool speed.

ST9103A may be factory−configured to operate heat speed in this mode.

Thermostat ends call for fan.
(G terminal is de−energized.)

Circulating fan is de−energized.

Limit switch string opens. Oil primary control shut off the burner.

Circulating fan is energized immediately at heat speed.

ST9103A opens oil primary control T−T connections.

Circulating fan runs as long as limit string stays open.

If there is a call for cooling or fan, the circulating fan switches from heat speed to cool
speed.

Limit switch string closes. ST9103A begins heat fan off delay sequence.

Circulating fan turns off after the selected heat fan off delay timing.

ST9103A closes oil primary control T−T connections.

Oil primary control is energized, initiating burner light off.

Continuous circulating fan is connected.
(Optional connectors are available for separate circu­lating fan speed tap.)

Circulating fan is energized at low speed when there is no call for heat, cool or fan.

If fan operation is required by a call for heat, cool, or fan, the ST9103A switches off the
continuous fan speed tap before energizing the other fan speed.

Electronic air cleaner is connected.
(Optional connectors are available for 120 Vac elec­tronic air cleaner.)

Electronic air cleaner (EAC) connections are energized when the heat or cool speed of
the circulating fan is energized. EAC connections are not energized when the optional
continuous fan terminal is energized.

Humidity control is connected.
(Optional connectors are available for 120 Vac humidi­fier.)

Humidifier connections are energized when the burner motor is energized.

Page 19

Troubleshooting: Burner fails to start.

Source Procedure Causes Correction

Thermostat Check thermostat settings.

Thermostat in OFF or COOL Switch to HEAT.

Thermostat is set too low

Turn thermostat to higher tem­perature.

Safety Overloads

Check burner motor, primary
safety control, & auxiliary limit
switch.

Burner motor overload tripped Push reset button pump motor.

Primary control tripped on safe­ty

Reset primary control.

Auxiliary limit switch tripped on
safety

Reset auxiliary limit.

Power

Check furnace disconnect
switch & main disconnect.

Open switch Close switch.

Blown fuse or tripped circuit
breaker

Replace fuse or reset circuit
breaker.

Thermostat

Touch jumper wire across ther­mostat terminals on primary
control. If burner starts, then
fault is in the thermostat circuit.

Broken or loose thermostat
wires

Repair or replace wires.

Loose thermostat screw con­nection

Tighten connection.

Dirty thermostat contacts Clean contacts.

Thermostat not level Level thermostat.

Faulty thermostat Replace thermostat.

CAD Cell

Disconnect the flame detector
wires at the primary control. If
the burner starts, fault is in the
detector circuit.

Flame detector leads are
shorted

Separate leads.

Flame detector exposed to light Seal off false source of light.

short circuit in the flame detec­tor

Replace detector.

Primary Control

Place trouble light between the
black and white leads. No light
indicates that no power is going
to the control.

Primary or auxiliary control
switch is open

Check adjustment. Set the
maximum setting.

Jumper terminals; if burner
starts, switch is faulty, replace
control.

Open circuit between discon­nect switch and limit control

Trace wiring and repair or re­place it.

Low line voltage or power fail­ure

Call the power company.

Place trouble light between the
orange and white leads. No light
indicates faulty control.

Defective internal control circuit Replace the control.

Burner

Place the trouble light between
the black and white leads to the
burner motor. No light indicates
that no power is getting to the
motor.

Blown fuse Replace the fuse.

Place trouble light between the
black and white leads to the
blower motor. Light indicates
power to the motor and burner
fault.

Binding burner blower wheel

Turn off power and rotate the
blower wheel by hand. If seized,
free the wheel or replace the
fuel pump.

Sized fuel pump

Defective burner motor Replace the motor.

Page 20

Troubleshooting: Burner starts, but no flame is established.

Source Procedure Causes Correction

Oil Supply

Check tank gauge or use dip
stick.

No oil in tank Fill tank.

Coat dip stick with litmus paste
and insert into bottom of tank.

Water in oil tank

If water depth exceeds 1 inch,
pump or drain water.

Listen for pump whine. Tank shut−off valve closed Open valve.

Oil Filters & Oil Line

Listen for pump whine.

Oil line filter is plugged Replace filter cartridges.

Kinks or restriction in oil line Repair or replace oil line.

Plugged fuel pump strainer Clean strainer or replace pump.

Open bleed valve or gauge port.
Start the burner. No oil or milky
oil indicates loss or prime.

Air leak in oil supply line

Locate and correct leak.

Tighten all connections.

Oil Pump

Install pressure gauge on pump
and read pressure. Should not
be less than 140 psi.

Pump is partially or completely
frozen. No pressure and the
motor locks out on overload.

Replace pump.

Coupling disengaged or broken

− no pressure

Re−engage or replace coupling.

Fuel pressure too low Adjust to 100 psi.

Nozzle

Disconnect ignition leads. Ob­serve the oil spray (gun assem­bly must be removed from unit).
Inspect the nozzle for plugged
orifice or carbon build−up around
orifice.

Nozzle orifice plugged

Replace nozzle with the same
size, spray angle, and spray
type.

Nozzle strainer plugged

Poor or off center spray

Ignition Electrodes

Remove gun assembly and in­spect electrodes and leads.

Fouled or shorted electrodes

Clean electrode leads.

Dirty electrodes and leads

Eroded electrode tips

Clean electrode tips and reset
the gap to 5/32 inches and cor­rectly position tips.

Improper electrode gap spacing

Improper position of electrode
tips

Bad buss bar connection Retension and realign.

Cracked or chipped insulators Replace electrode.

Cracked or burned lead insula­tors

Replace electrode leads.

Ignition

Transformer

Connect ignition leads to the
transformer. Start burner and
observe spark. Check line volt­age to transformer primary.

Low line voltage

Check voltage at power source.
Correct cause of voltage drop
or call the power company.

Burned out transformer wind­ings.

Replace the transformer.

No spark or weak spark

Properly ground the transformer
case.

Burner Motor

Motor does not come up to
speed and trips out on overload.
Turn off power and rotate blower
wheel by hand to check for bind­ing or excessive drag.

Low line voltage

Check voltage at power source.
Correct cause of voltage drop
or the call power company.

Pump or blower overloading
motor

Correct cause of overloading.

Faulty motor Replace motor.

Page 21

Troubleshooting: Burner starts and fires, but lock out on safety.

Source Procedure Causes Correction

Poor Fire

After burner
fires, immedi­ately jumper
across flame
detector termi­nals at the pri­mary control.

If burner con­tinues to run,
this may be
due to poor
fire. Inspect
fire.

Unbalanced fire Replace nozzle

Too much air − −lean short fire

Reduce combustion air − check
combustion.

Too little air − − long dirty fire

Increase combustion air − check
combustion.

Excessive draft

Adjust barometric damper for
correct draft.

Too little draft or restriction

Correct draft or remove restric­tion.

Flame Detector

If fire is good,
fault is in the
flame detector.
Check detec­tor circuit.

Dirty cad cell face Clean cad cell face.

Faulty cad cell − exceeds 15000
hms

Replace cad cell.

Loose or defective cad cell
wires

Secure connections or replace
cad cell holder and wire leads.

Primary Control

If burner locks
out on safety,
fault is in the
primary con­trol.

Primary control circuit defective Replace primary control.

Troubleshooting: Burner Starts and Fires, but Loses Flame and Lock Out on Safety

Source Procedure Causes Correction

Poor Fire

After burner
fires, immedi­ately jumper
across flame
detector termi­nals at the pri­mary control.

If burner con­tinues to run
(does not lock
out of safety),
fault may be
due to poor
fire. Inspect
fire.

Unbalanced fire Replace nozzle

Too much air − − lean short fire

Reduce combustion air − check
combustion.

Too little air − − long dirty fire

Increase combustion air − check
combustion.

Excessive draft

Adjust barometric damper for
correct draft.

Too little draft or restriction

Correct draft or remove restric­tion.

Flame Detector

If fire is good,
fault is in the
flame detector.
Check detec­tor circuit.

Dirty CAD cell face Clean CAD cell face.

Faulty CAD cell − − exceeds
15000 hms

Replace CAD cell.

Loose or defective cad cell
wires

Secure connections or replace
cad cell holder and wire leads.

If burner loses
flame (does
not lock out on
safety), fault is
in the fuel sys­tem.

Pump loses prime − air slug Prime pump at bleed port

Oil Supply

Pump loses prime − air leak in
supply line

Check supply line for loose con­nections and tighten fittings.

Water slug in line Check oil tank for water (over 1

inch) pump or drain out water.

Partially plugged nozzle or
nozzle strainer

Replace nozzle.

Listen for pump whine

Restriction in oil line Clear restriction.

Plugged fuel pump strainer Clean strainer or replace pump.

Cold oil − outdoor tank Change to number 1 oil.

Page 22

Troubleshooting: Burner starts and fires, but short cycles (too little heat)

Source Procedure Causes Correction

Thermostat Check thermostat.

Heat anticipator set too low Correct heat anticipator setting.

Vibration at thermostat Correct source of vibration.

Thermostat in the path of a
warm air draft

Shield thermostat from draft or
relocate.

Limit Control

Connect voltmeter between line
voltage connections to primary
control (black & white leads). If
burner cycles due to power inter­ruption, it is cycling on limit.

Dirty furnace air filters Clean or replace filter.

Burner running too slow

Increase blower speed to main­tain proper temp. rise.

Blower motor seized or burned
out

Replace motor.

Blower bearings seized Replace bearings and shaft.

Blower wheel dirty Clean blower wheel.

Blower wheel in backward Reverse blower wheel.

Wrong motor rotation

Replace with properly rotating
wheel.

Restrictions in return or supply
air system

Correct cause of restriction.

Adjustable limit control set too
low

Reset limit to maximum stop
setting.

Power

If voltage fluctuates, fault is in the
power source. Recheck voltage
at the power source.

Loose wiring connection Locate and secure connection.

Low or fluctuating line voltage Call power company.

Troubleshooting: Burner runs continuously (too much heat).

Source Procedure Causes Correction

Thermostat

Disconnect
thermostat
wires at the pri­mary control.

If burner turns
off, fault is in
the thermostat
circuit.

Shorted or welded thermostat
contacts

Repair or replace the thermo­stat.

Stuck thermostat bimetal

Clear obstruction or replace
thermostat.

Thermostat not level Level thermostat.

Shorted thermostat wires Repair short or replace wires.

Thermostat out of calibration Replace thermostat.

Thermostat in cold draft

Correct draft or relocate the
thermostat.

Primary control

If burner does
not turn off,
fault is in the
primary control.

Defective primary control

Replace the defective primary
control.

Page 23

Troubleshooting: Burner runs continuously (too little heat).

Source Procedure Causes Correction

Combustion

Check burner
combustion for
CO2, stack tem­perature, and
smoke

Low CO

2

less

than 10%.

Too much combustion air Reduce combustion air.

Air leaks into heat exchanger
around inspection door, etc.

Correct cause of air leak.

Excessive draft

Adjust barometric draft con­trol for correct draft.

Incorrect burner head adjust­ment

Correct burner head setting.

High smoke
reading more
than a trace.

Dirty or plugged heat exchanger

Clean heat exchanger.

Readjust burner.

Insufficient draft Increase draft.

Incorrect burner head adjust­ment

Correct burner setting.

Too little combustion air Increase combustion air.

High stack tem­perature is
more than
550

_F Net.

Too little blower air

Increase blower speed to
maintain proper temp. rise.

Blower belt too loose (if
equipped)

Tighten blower belt.

Dirty or plugged heat exchanger Clean heat exchanger.

Dirty blower wheel Clean blower wheel.

Dirty furnace air filters Clean or replace filter.

Restricted or closed registers or
dampers

Readjust registers or damp­ers.

Oil Pressure

Inspect fire and check

oil pressure.

Partially plugged or defective
nozzle

Replace nozzle.

Oil pressure is too low: less
than 100 psi.

Increase oil pressure top
100psi.