Lennox OF23Q3/4-105, OF23Q3/4-120R, OF23Q3/4-120, OF23Q5-140, OF23Q5-154 Installation Instructions Manual



INSTALLATION

E 2002 Lennox Industries Inc.

Dallas, Texas, USA

Front

Flue Model

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.

INSTRUCTIONS

OF23 SERIES UNITS

OIL UNITS

504,627M
38152A060
01/04

Supersedes 04/02

Table of Contents

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

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

OF23 Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . .

OF23 Start−Up & Performance Check List 2. . . . . . .

OF23 Unit Parts Arrangement 3. . . . . . . . . . . . . . . . . . . .

OF23 Oil AFII Burner Parts Arrangement 4. . . . . . . . . .

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

Locate & Level Unit 4. . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

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

Flue Connect ions 11. . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

Oil Supply Lines Sizing 11. . . . . . . . . . . . . . . . . . . . . .

Connect Oil Supply Line and Filter 13. . . . . . . . . . . . .

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

Electrical Wiring 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Start−Up & Adjustment 15. . . . . . . . . . . . . . . . . . . . . . . . .

Service 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Troubleshooting 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

General

These instructions are intended as a general guide and do
not supersede local codes in any way. Only qualified tech­nicians can install and service the Lennox Elite
OF23 oil furnaces. In Canada, refer to CSA B139 for rec­ommended installation procedures. Consult authorities
who have jurisdiction before installation.

Litho U.S.A.

®

Series

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 qualified installer
or service agency.

CAUTION

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

01/04

*2P0104*

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 (front flue units only)
1− Direct intake collar (AFII burner units only)
Check the components for shipping damage. If you find any

damage, immediately contact the last carrier.

504,627M

Page 1

*P504627M*

OF23 Unit Dimensions − Inches (mm)

1-1/2

(38)

FLUE CONNECTION
OF23Q3/4-105/120R,

OF23Q5-140/154R
OF23Q5−175/210R

C

3/4

(19)

RETURN

E

OPENING

3/4

(19)

AIR FLOW

3/4

(19)

3-1/4

(83)

E

AIR

3/4

(19)

TOP VIEW

C

AIR FLOW

FLUE CONNECTION
OF23Q3/4-105/140 &

OF23Q5-140/154

(On Heat Exchanger)

ELECTRICAL INLETS

(Right Side Only)

FG

SUPPLY

AIR

OPENING

TOP FLUE

OUTLET

SIDE

FLUE OUTLET

CENTERING HOLE

(Field Fabricate

Either Side)

OPT. OUTDOOR

COMBUSTION

AIR INLET

CENTERING HOLE

(Field Fabricate

Right Side only)

A

B

1

(25)

Model No.

OIL PIPING INLET

(Both Sides)

SIDE VIEW FRONT VIEW

1 (25)

6-1/2
(165)

A B C D E x F (Supply) E x G (Return)

in. mm in. mm in. mm in. mm in. mm in. mm

OF23Q3/4-105/120 19-1/2 4959 37 940 52−1/2 1334 27 686 18 x 21 457 x 533 18 x 16 457 x 406

OF23Q3/4-105/120R 19-1/2 495 37 940 52−1/2 1334 27 686 18 x 21 457 x 533 18 x 16 457 x 406

OF23Q5-140/154 22-1/2 572 37 940 52−1/2 1334 27 686 21 x 21 533 x 533 21 x 16 533 x 406

OF23Q5-140/154R 22-1/2 572 37 940 52−1/2 1334 27 686 21 x 21 533 x 533 21 x 16 533 x 406

OF23Q5-175/210R 24 610 39−1/4 997 55 1397 29 737 22−1/2 x 23−1/8 572 x 587 22−1/2 x 16−1/2 572 x 419

OF23 Start−Up & Performance Check List

Job Name

Job Location
Installer
Unit Model No.

HEATING SECTION

Electrical Connections Tight?

Supply Voltage

Blower Motor Amps

Blower Motor H.P.

Blower Motor Lubrication O.K.?

Piping Connections Tight?

Burner Model No.

All Valves Open?

Serial Number

Oil Pump Pressure [recommended minimum 140 psi]

Job No.

City

City

Serial No.

Date

State
State

Serviceman

PROPER DRAFT

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

% CO2 (recommended 12%)

Flue Connections Tight?

Fan Control Setting (maximum 130_ F)

(55_C)

Temperature RiseFan Control Cutout

Filter Clean & Secure?

Vent Clear?

THERMOSTAT

Calibrated? Heat Anticipator Properly Set? Level?

Page 2

OF23 Unit Parts Arrangement

flue opening

clean-out port

limit switch

control box

with fan control

board

observation port

filter

indoor blower

heat exchanger

BeckettR AFII Burner

(Shown)

OF23 Oil AFII Burner Parts Arrangement

RETAINING

CLIP

HEAD SCREW

HEAD

INSULATOR

ADAPTER

FLANGE

GASKET

AIR TUBE

ASSY FOR

FB HEADS

1/4" HEX

FB−HEAD

NOZZLE

NOZZLE LINE

ELECTRODE HEAD

ASSY.

FLANGE

ELECTRODE

ASSY

AIR TUBE
SCREWS

PEDESTAL

PREMOUNTED OIL−DELAY VALVE

Figure 1

ELECTRONIC IGNITION

TRANSFORMER

REAR ACCESS

DOOR GASKET

REAR ACCESS

DOOR ASSY

MAIN

HOUSING

ASSY

SPLINED

NUT

ESCUTCHEON

PLATE

CONNECTOR

TUBE

FUEL PUMP

COUPLING

clean−out

port

IGNITOR

MOTOR

PRIMARY

CONTROL

BLOWER

WHEEL

4X4

BOX

0

3
4
5

6
7
8

AIR
ADJ.
DIAL

INLET

AIR SCOOP

Figure 2

Page 3

Requirements

Table 1

Combustion Air Opening Dimensions

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

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 OF23 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.

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.

IMPORTANT

An opening to the outside for combustion air is
strongly recommended, especially in new homes.
Refer to table 1 or the unit plate for specific combus­tion air opening dimensions.

Model No.

O23−105/120

O23−105R/120R

O23−140/154

O23−140R/154R

O23−175R/210R
O23−175R/210R

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.

Combustion Air Opening

Dimensions (2 required)

10" X 20" (254 mm X 508 mm)

11" X 22" (279 mm X 559 mm)

20" X 40" (508 mm X 1016 mm)

Table 2

Installation Clearances

Clearances

top of plenum and duct 2 (51)

plenum sides 3 (76)

sides* 6 (152)

rear 24 (610)

front 4 (102)

flue pipe measured vertical**

(measured from above)

NOTE−Service access clearance must be maintained.

*Clearance to allow inspection of furnace and flue connector
shall be provided. 24" (610 mm) at rear and on one side of furnace should
be allowed for cleaning and service of the blower.
**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 and CSA 189.

NOTE − When service clearances are greater than fire
protection clearances, service clearances take prece­dence.

Unit must be adjusted to obtain a temperature rise within
the range listed in table 3 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.

All Unit Sizes

inches (mm)

9 (229)

Page 4

Locate & Level the Unit

The compact design of this furnace makes it ideal for a
basement or utility room installation. Choose a central
location for the furnace so that supply air ducts approxi­mately the same length. This will allow each room to re­ceive the proper amount of heat. The furnace should be
placed so that the flue connection to the chimney will be of
minimum length and have a minimum number of elbows.

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

or O2 Analyzer

2

D Smoke tester
D Pressure gauge
D High temperature thermometer
D Oil vacuum gauge
D Beckett T−500 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.

Nozzle Adjustment

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. This may easily be done by removing 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. Note that

OF23−105/120 and OF23−140/154 series units use the
Beckett AFII burner. OF23−175/210R series units use the
Beckett AFG burner.

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, just turn
the burner around in the vest panel area.

OF23 Series Burner Removal

First, loosen three nuts which

attach burner to vest panel.

Next, rotate burner counter-

clockwise on slots then pull

toward you.

Figure 3

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. Corrections are
made by sliding the entire nozzle assembly forward or
backward within the blast tube (figure 4). At the same time,
nozzle alignment must be checked.

To check nozzle alignment, again insert the small end of
gauge 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.

Page 5

Beckett Oil Burner Nozzle Adjustment

Burner must be removed from

furnace for this procedure.

gauge

To Adjust Nozzle

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

2

1

Figure 4

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.

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

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).

thimble

combustible

wall

vent pipe

Figure 5

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 6

Front Flue / Masonry Chimney

barometric

control*

(in either location)

Rear Flue / Masonry Chimney

barometric

control*

(in either location)

clean out

liner

clean out

masonry

chimney

liner

clean out

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.

Front Flue / Factory−Built Chimney

barometric

control*

(in either location)

factory

built

chimney

clean out

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

masonry

chimney

Figure 6

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.

drain for

condensate

Rear Flue / Factory−Built Chimney

barometric

control*

(in either location)

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

factory

built

chimney

drain for

condensate

Figure 7

Page 7

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.

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.

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

t

Oil Ven

Oil

Furnace

Water

Heater

Openings

(To Adjacent Room)

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

Page 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).

Figure 8

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 10). When communi­cating 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

(Inlet Air from Crawl Space and Outlet Air to

Chimney or

Oil Vent

Oil

Furnace

Ventilation

Louvers

(For unheated

crawl space)

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.

All Air From Outside

Ventilated Attic)

Ventilation Louvers

(Each End Of Attic)

Outlet

r

Ai

Water

Heater

Inlet

Air

Equipment In Confined Space

All Air From Outside

Chimney

Or Oil

Vent

Oil

Furnace

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.

Water

Heate

r

Outlet Air

Inlet Air

Figure 11

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.

Figure 9

Equipment In Confined Space

All Air From Outside

(All Air Through Ventilated Attic)

Chimney

or Oil

Vent

Outlet

Air

Oil

Furnace

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)

Figure 10

Inlet Air

(Ends 12"

Above Bottom)

Water

r

Heate

CAUTION

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

CAUTION

The barometric control 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 or injury.

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 6 feet
(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.

Page 9

To convert the AFII burner from confined space to outside
combustion air, remove the three screws which attach 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. Use a barometric relief
in the intake to reduce the chance of sooting.

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 its 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 OF23 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.

The barometric draft control must be installed within 18
inches of the furnace flue outlet. See figure 12 for baromet­ric draft control location.

Do not common vent with any other appliance when using
sidewall vent system.

The maximum equivalent length of pipe is 70 equivalent
feet. A 90_ elbow equals 6 ft. Minimum length is 15 equiva-
lent 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.

Front Flue / Horizontal Venting

barometric

control*

control for

horizontal

venting

Rear Flue / Horizontal Venting

barometric

control*

horizontal

venting

control

*Barometric control must be installed in the horizontal venting
system and located within 18" of flue outlet of furnace.

Figure 12

Page 10

Flue Connections

IMPORTANT

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

Radiation Shield Installation

combustible

material

unit

cabinet

noncombustible

spacers

A

see note 2

OF23 unit

(top)

radiation

shields

A

radiation shields

(see note 1)

flue

pipe

1" (25 mm)

min

12" (305 mm)

min

7" (178 mm)

min

B

see note 3

vent connector, plus 50% of the area of any additional flues
or vent connectors. Install the 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. 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.

of23 unit

(front)

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.

Figure 13

For front flue models, the enclosed exhaust pipe ring may
be used for pipe to exit the left or right side of cabinet. Cen­ter line marks are provided in cabinet.

Use 24 gauge or heavier galvanized smoke pipe and fit­tings to connect furnace to 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 largest flue or

Oil Supply Lines 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 with the oil tank 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. 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.

To determine the length of the run for piping, refer to table 2
.

Page 11

air vent

fill

pipe

Oil Piping

One-Pipe System

pump

fuel

Aux

Filter

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.

Oil

Tank

Shut−off

Valve

8 ft (2.4 m)

Maximum

One Pipe Lift

Figure 14

Table 2

One−Pipe Oil 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, a single−stage fuel pump should be used
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 3 .

Oil Piping

Two-pipe System

Air Vent

Fill

Pipe

Return

pipe

Oil

Tank

3"−4"

(76 mm −102 mm)

Return

pipe

outside tank fuel pump above bottom of tank

R

fuel

pump

Aux

Filter

Inlet

H

Figure 15

IMPORTANT

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

Table 3

Two−Pipe Maximum Pipe Length (H + R)

3450 RPM − 3 GPH (11.4 LPH)

Lift H"

0’

(0.0 m)

2’

(0.6 m)

4’

(1.2m)

6’

(1.8m)

8’

(2.4m)

10’

(3.0m)

12’

(3.7m)

14’

(4.3m)

16’

(4.9m)

18’

(5.5m)

3/8" (10 mm) OD

Tubing

Single

Stage

84’

(25.6 m)

73’

(22.3 m)

63’

(19.2 m)

52’

(15.8 m)

42’

(12.8 m)

31’

(9.4 m)

21’

(6.4 m)

−−−

−−−

Two

Stage

93’

(28.3 m)

85’

(25.9 m)

77’

(23.5 m)

69’

(21.0 m)

60’

(18.3 m)

52’

(15.9 m)

44’

(13.4 m)

36’

(11.0 m)

27’

(8.2 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.

1/2" (12 mm) OD

Tubing

Single

Stage

100’

(30.5 m)

100’

(30.5 m)

100’

(30.5 m)

100’

(30.5 m)

100’

(30.5 m)

100’

(30.5 m)

83’

(25.3 m)

41’

(12.5 m)

−−−

Two

Stage

100’

(30.5 m)

100’

(30.5 m)

100’

(30.5 m)

100’

(30.5 m)

100’

(30.5 m)

100’

(30.5 m)

100’

(30.5 m)

100’

(30.5 m)

100’

(30.5 m)

(23.2 m)

76’

Page 12

1 − Connect the inlet pipe to the pump inlet. Start the burner.

2 − Arrange the primary burner control for continuous op-

eration during purging. See figure 14.

3 − Turn the bleed valve one turn counterclockwise.

4 − Bleed the unit until all air bubbles disappear.

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

Table 4

Oil Filters (All Models)

Oil Filters

10 micron filter (no mounting bracket) 81P89

10 micron filter (mounting bracket) 53P92

10 micron replacement cartridge for filter, 45 gph 53P93

Cat.

Number

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 two-pipe
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 4
lists the filters for the OF23 furnace.

Consult the burner manufacturer’s instructions that are in­cluded with the unit for further details concerning oil supply
pipe connections.

Filter restriction indicator gauge 53P90

Leak Check

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

Oil Line 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 terminal designations on fan
control board.

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

2− Install 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 figure 16 for OF23 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 in operation.

Page 13

Fan Control Board

thermostat

terminal strip

Figure 16

Typical OF23 Wiring Diagram

Figure 17

Page 14

Typical OF23 Wiring Diagram

Figure 18

Page 15

Start−Up & Adjustment

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 unit.

readings, subtract the readings. The difference in tempera­tures in the supply and return air plenums should approxi­mate the temperatures listed in table 5 and the appliance
rating plate. If not, adjust the blower motor pulley to adjust
the blower speed.

Table 5

OF23

Unit

nozzle size,

spray, angle, &

pattern

input

rating

BTU/HR

output

rating

BTU/HR

head temp

rise F°

CAUTION

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

CAUTION

Blower access 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 nut on bleed port.

NOTE − A two−line 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 once.
See part arrangement illustration.

CAUTION

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

−105 .65GPH- .80° B 105,000 85,000 FB3 60

−105R .65GPH- .80° B 105,000 85,000 FB3 65

−120 *.75GPH-.80° B 119,000 97,000 FB3 70

−120R *.75GPH−.80° B 119,000 97,000 FB3 70

−140 .85GPH- .80° B 140,000 113,000 FB6 60

−140R .85GPH− .80° B 140,000 113,000 FB6 65

−154 *1.00GPH- .80° B 154,000 125,000 FB6 60

−154R *1.00GPH- .80° B 154,000 125,000 FB6 70

−175 1.10GPH- .80° B 175,000 142,000 FB6 70

−210R 1.25GPH- .80° B 210,000 166,000 FB6 70

*Nozzle must be field provided for field conversion to higher

heating input.

Oil burner pump pressure is 140 psi for each unit.

C − Limit Control

Limit Control  Do not adjust 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.

Delay Off Switch Settings

5− If burner fails to light again, refer to the troubleshooting

section in this manual.

A − Fuel Pump Pressure Adjustment

Measure fuel pump pressure with unit off. Attach pressure
gauge to pump outlet. Turn unit on and check pressure and
compare to table 3. Adjust if necessary.

B − Temperature Rise Adjustment

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

Page 16

120 sec90 sec60 sec

150 sec

Figure 19

E − Burner Adjustment

The following instructions are essential to the proper op­eration of OF23 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.

the room air temperature from the stack temperature. This
will give you the net stack temperature. Use the efficiency
charts provided in most CO

analyzers to determine fur-

2

nace efficiency.

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.

2 − Overfire Draft

This test should be taken with the burner in operation. Re­move the screw from the center of the inspection door. 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 0
and #1 smoke. This is the starting point. Do not stop here.

4 − CO

Test

2

Again, take the 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
CO

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

2

the CO

to 10%.

2

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

2

5 − Retest the Smoke

With a drop in the CO

and increase in the air you should

2

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

Service

A − Servicing Filter

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

1− Throw-Away Type Filters  Filters should be checked

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

2− Reusable Type Filters  Filters should be checked

monthly and cleaned when necessary to assure prop­er furnace operation. Use warm water and a mild de­tergent. Replace filter when dry. Permanent filters
supplied with OF23 furnaces do not require oiling after
cleaning. Examine filter label for any for special in­structions that may apply.

B − Blower

Blower motor is pre-lubricated 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 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 burner, blower deck and vestibule area.

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

Page 17

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-

Troubleshooting: Fan Board Operating Sequence

Action System Response

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.

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

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

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

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

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

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

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

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

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 motor is de−energized.

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

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.

Circulating fan is energized at the cool speed.

Cooling compressor turns on immediately.

Circulating fan and cooling compressor turn off immediately.

Circulating fan is energized immediately at cool speed.

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

Circulating fan is de−energized.

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

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

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

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

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

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.

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.

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 (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.

Humidifier connections are energized when the burner motor is energized.

Page 18

Troubleshooting: Burner fails to start.

y

yy

Check f

t

Thermostat

ostat te a s o p a y

fault is in the thermostat circuit

the burner starts, fault is in the

Pri

ili

l

indicat

black

hite leads to th

p

blower wheel by hand. If seized,
power to the motor and burner

Source Procedure Causes Correction

Thermostat in OFF or COOL Switch to HEAT.

Thermostat Check thermostat settings.

Check burner motor, primary

Safety Overloads

Power

CAD Cell

Primary Control

Burner

safety control, & auxiliary limit
switch.

urnace disconnec

switch & main disconnect.

Touch jumper wire across ther­mostat terminals on primary
control. If burner starts, then

Disconnect the flame detector
wires at the primary control. If

detector circuit.

Place trouble light between the
black and white leads. No light

es that no power is going

to the control.

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

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.

Place trouble light between the

and w

blower motor. Light indicates

ower to the motor and burner

fault.

Thermostat is set too low

Burner motor overload tripped Push reset button pump motor.

Primary control tripped on safe­ty

Auxiliary limit switch tripped on
safety

Open switch Close switch.

Blown fuse or tripped circuit
breaker

Broken or loose thermostat
wires

Loose thermostat screw con­nection

Dirty thermostat contacts Clean contacts.

.

Thermostat not level Level thermostat.

Faulty thermostat Replace thermostat.

Flame detector leads are
shorted

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

short circuit in the flame detec­tor

mary or aux

switch is open

Open circuit between discon­nect switch and limit control

Low line voltage or power fail­ure

Defective internal control circuit Replace the control.

Blown fuse Replace the fuse.

Binding burner blower wheel

e

Sized fuel pump

Defective burner motor Replace the motor.

ary contro

Turn thermostat to higher tem­perature.

Reset primary control.

Reset auxiliary limit.

Replace fuse or reset circuit
breaker.

Repair or replace wires.

Tighten connection.

Separate leads.

Replace detector.

Check adjustment. Set the
maximum setting.

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

Trace wiring and repair or re­place it.

Call the power company.

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

Page 19

Troubleshooting: Burner starts, but no flame is established.

O tes&O e

Start the b

ilk

Air leak i

pggpp

pray (g

serve the oil spray (gun assem

spect t e o e o p ugged

t
Cl

gap

the gap to 5/32 inches and cor-

g

to transformer primary

pp

ing or excessive drag

Source Procedure Causes Correction

Oil Supply

Oil Filters & Oil Line

Oil Pump

Check tank gauge or use dip
stick.

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

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

Listen for pump whine.

Open bleed valve or gauge port.

urner. No oil or m

oil indicates loss or prime.

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

No oil in tank Fill tank.

Water in oil tank

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.

y

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

Coupling disengaged or broken

− no pressure

Fuel pressure too low Adjust to 100 psi.

n oil supply line

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

Locate and correct leak.

Tighten all connections.

Replace pump.

Re−engage or replace coupling.

Nozzle

Ignition Electrodes

Ignition

Transformer

Burner Motor

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

Remove gun assembly and in­spect electrodes and leads.

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

Motor does not come up to
speed and trips out on overload.
Turn off power and rotate blower
wheel by hand to check for bind-

un assem-

.

.

Nozzle orifice plugged

Nozzle strainer plugged

Poor or off center spray

Fouled or shorted electrodes

Dirty electrodes and leads

Eroded electrode 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

Low line voltage

Burned out transformer wind­ings.

No spark or weak spark

Low line voltage

Pump or blower overloading
motor

Faulty motor Replace motor.

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

ype.

ean electrode leads.

Clean electrode tips and reset
the
rectly position tips.

Replace electrode leads.

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

Replace the transformer.

Properly ground the transformer
case.

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

Correct cause of overloading.

to 5/32 inches and cor-

Page 20

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

due to poor

,

If fire is good

fault may be

p

After burner

,

If fire is good

Fl

detector termi-

in the fuel sys

Source Procedure Causes Correction

Unbalanced fire Replace nozzle

Reduce combustion air − check
combustion.

Increase combustion air − check
combustion.

Adjust barometric damper for
correct draft.

Correct draft or remove restric­tion.

Replace cad cell.

Secure connections or replace
cad cell holder and wire leads.

Poor Fire

Flame Detector

Primary Control

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

If burner con­tinues to run,
this may be

fire. Inspect
fire.

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

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

,

Too much air − −lean short fire

Too little air − − long dirty fire

Excessive draft

Too little draft or restriction

Dirty cad cell face Clean cad cell face.

Faulty cad cell − exceeds 15000
hms

Loose or defective cad cell
wires

Primary control circuit defective Replace primary control.

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

Source Procedure Causes Correction

Unbalanced fire Replace nozzle

Poor Fire

ame Detector

Oil Supply

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

Listen for pump whine

If burner con­tinues to run
(does not lock
out of safety),

due to poor
fire. Inspect
fire.

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

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

,

Too much air − − lean short fire

Too little air − − long dirty fire

Excessive draft

Too little draft or restriction

Dirty CAD cell face Clean CAD cell face.

Faulty CAD cell − − exceeds
15000 hp

Loose or defective cad cell
wires

Pump loses prime − air slug Prime pump at bleed port

Pump loses prime − air leak in
supply line

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

Partially plugged nozzle or
nozzle strainer

Restriction in oil line Clear restriction.

Plugged fuel pump strainer Clean strainer or replace pump.

Cold oil − outdoor tank Change to number 1 oil.

Reduce combustion air − check
combustion.

Increase combustion air − check
combustion.

Adjust barometric damper for
correct draft.

Correct draft or remove restric­tion.

Replace CAD cell.

Secure connections or replace
cad cell holder and wire leads.

Check supply line for loose con­nections and tighten fittings.

inch) pump or drain out water.

Replace nozzle.

Page 21

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

Thermostat

Check thermostat

(

Limit Control

control (black & white leads). If

P

If burner turns

Thermostat

the th

t

sco ect

circuit.

wires at the pri

Source Procedure Causes Correction

Heat anticipator set too low Correct heat anticipator setting.

Thermostat Check thermostat.

Connect voltmeter between line
voltage connections to primary

Limit Control

ower

control
burner cycles due to power inter­ruption, it is cycling on limit.

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

black & white leads). If

.

Vibration at thermostat Correct source of vibration.

Thermostat in the path of a
warm air draft

Dirty furnace air filters Clean or replace filter.

Burner running too slow

Blower motor seized or burned
out

Blower bearings seized Replace bearings and shaft.

Blower wheel dirty Clean blower wheel.

Blower wheel in backward Reverse blower wheel.

Wrong motor rotation

Restrictions in return or supply
air system

Adjustable limit control set too
low

Loose wiring connection Locate and secure connection.

Low or fluctuating line voltage Call power company.

Shield thermostat from draft or
relocate.

Increase blower speed to main­tain proper temp. rise.

Replace motor.

Replace with properly rotating
wheel.

Correct cause of restriction.

Reset limit to maximum stop
setting.

Troubleshooting: Burner runs continuously (too much heat).

Source Procedure Causes Correction

Thermostat

Primary control

Disconnect
thermostat

mary control.

If burner turns
off, fault is in

ermosta

circuit.

-

-

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

Shorted or welded thermostat
contacts

Stuck thermostat bimetal

Thermostat not level Level thermostat.

Shorted thermostat wires Repair short or replace wires.

Thermostat out of calibration Replace thermostat.

Thermostat in cold draft

Defective primary control

Repair or replace the thermo­stat.

Clear obstruction or replace
thermostat.

Correct draft or relocate the
thermostat.

Replace the defective primary
control.

Page 22

Troubleshooting: Burner runs continuously (too little heat).

L

CO

l

Dirt

g

Check b

reading more
CO2, stack tem

High stack tem

550 F Net.

Oil P

Inspect fire and check

Source Procedure Causes Correction

Too much combustion air Reduce combustion air.

Combustion

ressure

urner
combustion for
CO2, stack tem­perature, and
smoke

Inspect fire and check

oil pressure.

Air leaks into heat exchanger

ow

2

than 10%.

ess

around inspection door, etc.

Excessive draft

Incorrect burner head adjust­ment

y or plugged heat exchanger

High smoke
readin

more

Insufficient draft Increase draft.

than a trace. Incorrect burner head adjust-

ment

Too little combustion air Increase combustion air.

Too little blower air

Blower belt too loose (if

High stack tem­perature is
more than

_F Net.

550

equipped)

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

Partially plugged or defective
nozzle

Oil pressure is too low: less
than 100 psi.

Correct cause of air leak.

Adjust barometric draft con­trol for correct draft.

Correct burner head setting.

Clean heat exchanger.

Readjust burner.

Correct burner setting.

Increase blower speed to
maintain proper temp. rise.

Tighten blower belt.

Readjust registers or damp­ers.

Replace nozzle.

Increase oil pressure top
100psi.

Page 23