Full Text Searchable PDF User Manual
FOR YOUR SAFETY
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, al-
teration, service or maintenance can cause injury
or property damage. Refer to this manual. For as-
sistance or additional information, consult a quali-
fied installer, service agency or the oil supplier.
P*HB (UPFLOW)
INSTALLATION
INSTRUCTION
OIL-FIRED
WARM AIR FURNACES
Supersedes: 035-14289-000-A-300
035-14289-000-A-1101
CAUTION
THIS PRODUCT MUST BE INSTALLED IN STRICT COM-
PLIANCE WITH THE ENCLOSED INSTALLATION IN-
STRUCTIONS AND ANY APPLICABLE LOCAL, STATE,
AND NATIONAL CODES INCLUDING BUT NOT LIM-
I T E D T O , B U I L D I N G, E L E C T R I C A L A N D M E-
CHANICAL CODES.
WARNING
IMPROPER INSTALLATION MAY CREATE A CONDITION
WHERE THE OPERATION OF THE PRODUCT COULD
CAUSE PERSONAL INJURY OR PROPERTY DAMAGE.
P*LB LOWBOY
NRTL/C
P*DH (DOWNFLOW
HORIZONTAL)
IMPORTANT: SAVE THESE INSTRUCTIONS
FOR FUTURE REFERENCE
INTRODUCTION
Please read these instructions completely and carefully before
installing and operating the furnace. Please refer to the data on
pages 4 & 5 for performance and dimensional data.
In the United States the installation of the furnace and related
equipment shall be installed in accordance with the regulations
of ANSI NFPA No. 31 (latest edition), Installation of Oil Burning
Equipment, as well as in accordance with local codes.
In Canada, the installation of the furnace and related equip-
ment shall be installed in accordance with the regulations of
CAN/CSA -- B139--M91 (latest edition), Installation Code For
Oil Burning Equipment, as well as in accordance with local
codes.
Regulations prescribed in the National Codes and Local regu-
lations take precedence over the general instructions provided
on this installation manual. When in doubt, please consult your
local authorities.
All models are shipped assembled and pre--wired except model
P*LBX20F19001 where the blower section is separate. The
blower section is shipped together with the burner section, but
must be assembled together during installation. The furnace
should be carefully inspected for damage when being unpacked.
HEAT LOSS
The maximum hourly heat loss for each heated space shall be
calculated in accordance with the procedures described in the
following manuals.
In the United States ACCA Manual “J”. titled, “Load Calcula-
tion” published by the Air Conditioning Contractors of America,
describes a suitable procedure for calculating the maximum
hourly heat loss.
In Canada, use the Heating, Refrigeration and Air Conditioning
Institute of Canada (HRAI), or by any other method which is
suitable for local conditions, provided the results obtained are
in substantial agreement with and not less than those obtained
using the procedure described in the manual.
LOCATION OF UNIT
The furnace should be located such that the flue connection to
the chimney is short, direct and consists of as few elbows as
possible. When possible, the unit should be centralized with re-
spect to the supply and return air duct work. A central location
minimizes the trunk duct sizing. .
The minimum installation clearances are listed in Table 1.
2
Unitary Products Group
035-14289-000 Rev. A (0701)
TABLE OF CONTENTS
Introduction................................................................2
Heat Loss ..................................................................2
Unit Location/Clearances ..........................................2
Air Conditioning Applications ................................2-3
Combustion Air..........................................................3
Downflow/Horizonal Applications ..............................3
Chimney Venting .......................................................3
Unit Dimensions & Physical Data.........................4 - 5
Barometric Damper ...................................................6
Fan / Limit Control .....................................................6
Electrical Connections...............................................7
Fuel Oil Piping ...........................................................7
Oil Filter .....................................................................8
Oil Burner Nozzles ....................................................8
Oil Burner Adjustment ...............................................8
Oil Burner Electrodes ................................................8
Oil Burner Primary Control ........................................8
Air Blower ..................................................................8
Maintenance/Service............................................9 - 9
Operating Instructions ...............................................9
Oil Burner Air Adjustment..........................................9
Start Up ...................................................................10
Sequence of Operation ...........................................10
Check Out ...............................................................10
NOMENCLATURE
P * HB X 12 F 080 01
Voltage Code = 120 - 1 - 60
Nominal capacity
(MBH Output)
Heating Fuel
F = Fuel Oil
CFM (x100)
Cabinet
X = Non-Standard
Product Identifier
HB = Upflow,
DH = Downflow / Horizontal
LB = Lowboy
Product Generation
May be 1, 2, or 3
Product Category
P = Furnace
TABLE 1 - CLEARANCES TO COMBUSTIBLES (INCHES)
CLEARANCE
FROM
UPFLOW
DOWNFLOW / HORIZONTAL
LOWBOY
80 MBH
120 MBH
80 MBH
120 MBH
DOWNFLOW
HORZ.
DOWNFLOW
HORZ.
TOP
1
1
0
6
0
3
3
FRONT
24
24
6***
24
16***
24
24
SIDES
1
1
1
1
1
1
Side 1 = 6
Side 2 = 18
REAR
1
1
1
1
1
1
24
BOTTOM
0
0
0****
1
0****
1
0**
S. A. PLENUM
1
1
1
1
1
3
1
FLUE PIPE
18*
18*
18*
18*
18*
18*
18*
NOTE: Adquate clearance should be provided over and above these clearances, as required for service access.
* May be 9 inches in Canada
** Elevated on 2-1/2 inch bricks
*** Front clearance required for servicing
**** With floor base accessory
AIR CONDITIONING APPLICATIONS
If the furnace is used in conjunction with air conditioning, the
furnace shall be installed in parallel with or upstream from the
evaporator coil to avoid condensation in the heat exchanger.
In a parallel installation, the dampers or air controlling means
must prevent chilled air from entering the furnace. If the damp-
ers are manually operated, there must be a means of control to
prevent the operation of either system unless the dampers are
in the full heat or full cool position.
The air heated by the furnace shall not pass through a refrig-
eration unit unless the unit is specifically approved for such
service.
The blower speed must be checked and adjusted to compen-
sate for the pressure drop caused by the evaporator coil. Refer
to Page 12 for recommended wiring and electrical connections
of the air conditioning controls.
COMBUSTION AIR
If the furnace is installed in a closet or utility room, two openings
must be provided connecting to a well ventilated space (full
basement, living room or other room opening thereto, but not a
bedroom or bathroom).
One opening shall be located above the level of the upper vent
opening and one opening below the combustion air inlet open-
ing in the front of the furnace. Each opening shall have a mini-
mum free area of 1
1
2
square inches per 1,000 Btu/h of total
input rating of all appliances installed in the room.
For furnaces located in buildings of unusually tight construc-
tion, such as those with high quality weather stripping, caulk-
ing, windows and doors, or storm sashed windows, or where
basement windows are well sealed, a permanent opening
communicating with a well ventilated attic or with the outdoors
shall be provided, using a duct if necessary.
The duct opening shall have a free area of 1
1
2
square inches
per 1,000 Btu/h of total input rating of all appliances to be in-
stalled. When a furnace is installed in a full basement, infiltra-
tion is normally adequate to provide air for combustion and
draft operation. Furnace rooms under 700 sq. ft. (65m
3
) should
automatically be treated as confined space.
DOWNFLOW/HORIZONTAL FURNACES
Downflow/horizontal models (P*DHX12F08001 & P*-
DHX16F12001) are factory shipped for downflow installation.
Downflow
If the furnace is to be installed in a downflow application, a com-
bustible floor base must be used (either 1CB0312, or
1CB0316). Refer to Figure 1.
Horizontal
For applying the furnace in a horizontal left or horizontal right
application follow these steps.
1. Rotate the furnace 90 degrees to the desired position.
2. Remove three nuts and washers fastening the oil burner
assembly to the furnace. Rotate the oil burner assembly to
an upright position (ignition transformer and/or protector
relay control should be on top).
3. Realign the oil burner assembly to the combustion cham-
ber (fire pot) and then secure with three nuts and washers.
4. Remove the cover from the flue collar.
5. Remove the screws securing the flue collar to the furnace
and then rotate the flue collar 90 degrees, such that the
venting attaches to the top.
6. Secure the flue collar to the furnace, then reinstall the flue
collar cover.
7. Horizontal-right applications using model P*DHX12F080
also require relocating the limit control to the alternative lo-
cation near the top of the unit (refer to Figure 2).
For non-suspended horizontal applications, maintain clear-
ances as shown on Table 1. Installation on a combustible floor
requires a clearance of 1". This can be done by using non--
combustibles such as 1" channel iron or similar material. The
furnace must be supported in such a way to prevent twisting or
sagging of the cabinet.
For suspended horizontal applications maintain clearance as
shown in Table 3. Remove the four circular knockouts on the
top panel and the four knockouts on the bottom panel.
The removed knockouts allow 3/8" threaded rod to be inserted
through the interior of the furnace. Refer to Figure 2.
Use care when inserting rods since the foil backed insulation
can be easily ripped and torn. Secure the furnace with 2" mini-
mum slotted angle or equilavent. The furnace must be sup-
ported in such a way to prevent sagging or twisting of the
cabinet.
Unitary Products Group
3
035-14289-000 Rev. A (0701)
DOWNFLOW
FURNACE
SUB BASE
ASSEMBLY
COMBUSTIBLE
FLOOR
DUCT
CONNECTION
20-½ X 20-½
FRONT VIEW
SIDE VIEW
1 IN.
1 IN.
1 IN.
1 IN.
2" MIN.
THREADED ROD 3/8'
NUT
WASHER
FURNACE
SLOTTED ANGLE
WASHER
NUT
JAM NUT.
SIDE VIEW
END VIEW
FIGURE 2 - HORIZONTAL SUSPENDED APPLICATION
HANGER ARRANGEMENT
FIGURE 1 - DOWNFLOW APPLICATION
COMBUSTIBLE FLOOR BASE
4
Unitary Products Group
035-14289-000 Rev. A (0701)
MODEL
DIMENSIONS - INCHES
A
HEIGHT
B
WIDTH
C
DEPTH
D
E
F
G
J
K
H
FLUE
CONNECT.
SUPPLY AIR
BOTTOM RETURN
SIDE RETURN
WIDTH
DEPTH
WIDTH
DEPTH
HEIGHT
DEPTH
UPFLOW
P*HBX12F08001
49-5/8
22
31
20-1/2
20
14
22
14
22
5
P*HBX16F10001
58-1/4
22
30-3/4
20-1/2
20
14
22
14
22
6
DOWNFLOW / HORIZONTAL
SUPPLY AIR
RETURN AIR
P*DHX12F08001
51
22
31-1/4
19
19
18
18
—
—
5
P*DHX16F12001
62
22-1/4
22-1/4
20-1/2
20-1/2
18
18
—
—
6
LOWBOY
SUPPLY AIR
RETURN AIR
P*LBX12F08001
31
22
43
20-1/2
18-5/8
20-1/2
18-5/8
—
—
5 (REAR)
P*LBX16F12001
41
22
52-1/2
20-1/2
18-5/8
20-1/2
18-5/8
—
—
6 (REAR)
P*LBX16F14501
41
22
52-1/2
20-1/2
18-5/8
20-1/2
18-5/8
—
—
6 (REAR)
P*LBX20F19001
56
26
49
24
22
24
22
—
—
7 (REAR)
TABLE 2 - UNIT DIMENSIONS
*
,
)
C
E
K
H
J
BOTTOM VIEW
G
F
*
+
,
-
.
/
0
,
-
)
*
+
,
-
.
/
0
,
-
)
UPFLOW - MODELS P*HB
DOWNFLOW/HORIZONTAL - MODEL P*DH16F12001
(Exposed burner)
DOWNFLOW/HORIZONTAL - MODEL P*DH12F08001
Unitary Products Group
5
035-14289-000 Rev. A (0701)
*
,
)
B
D
A
8-1/2
C
E
F
2-½
H
LOWBOY - MODELS P*LBX16F12001, P*LBX16F14501, P*LBX16F19001
LOWBOY - MODEL P*LBX12F08001 (Exposed Burner)
MODEL
HEATING MBH
1
OIL
RATE
GPH
AFUE
%
2
CFM @
.5 IWG
E.S.P.
3
UNIT
AMPS
MAX.
OVER-
CURRENT
PROTECT.
WIRE
SIZE
AWG
BLOWER
FILTERS
QTY. &
SIZE
ADD-ON
COOLING
INPUT *
OUT-
PUT
SIZE
HP
TONS
NOM.
CFM
UPFLOW
P*HBX12F08001
91
80
.65
82.0
1291
12.0
15
14
10 x 10
1/2
(1) 16 x 25
2, 2-
1
2
, 3
1200
P*HBX16F10001
119
100
.85
82.7
1445
12.0
15
14
10 x 10
1/2
(1) 16 x 25
3, 3-
1
2
, 4
1600
DOWNFLOW / HORIZONTAL
P*DHX12F08001
91
80
.65
82.0
1291
12.0
15
14
11x 10
1/2
(1) 120x 20
2, 2-
1
2
, 3
1200
P*DHX16F12001
140
120
1.0
80.1
1593
12.0
15
14
11 x 10
1/2
(1) 20 x 20
3, 3-
1
2
, 4
1600
LOWBOY
P*LBX12F08001
91
80
.65
85.1
1717
12.0
15
14
12 x 9
1/2
(1) 20 x 20
2, 2-
1
2
,3, 3-
1
2
,4
1200
P*LBX16F12001
140
120
1.0
83.4
1585
12.0
15
14
12 x12
1/2
(1) 20 x 25
3, 3-
1
2
, 4
1600
P*LBX16F14501
168
145
1.20
83.5
1585
12.0
15
14
12 x 12
1/2
(1) 20 x 25
3, 3-
1
2
, 4
1600
P*LBX20F19001
231
190
1.65
78.0
2135
12.0
15
14
12 x 12
3/4
(2) 20 x 25
3-
1
2
, 4, 5
2000
* Standard input as shipped. See Table 3, Page 8 for alternate firing rates
.
1
For Altitudes above 2000 feet, reduce ratings 4% for each 1000 feet above sea level.
2
AFUE (Annual Fuel Utilization Efficiency) determined using DOE test procedure, isolated combustion.
3
Available external static pressure is at furnace outlet and ahead of cooling unit.
PHYSICAL & ELECTRICAL DATA
CAUTION: Fan/limit control location is critical in the
P*DHX12F08001 horizontal positions. To operate ef-
fectively as a high limit control, the fan / limit control
must be installed in the upper position. See Figure 3.
CHIMNEY VENTING
The flue pipe should be as short as possible with horizontal
pipes sloping upward toward the chimney at a rate of one quar-
ter inch to the foot. The flue pipe should not be smaller in cross
sectional area than the flue collar on the furnace.
The flue pipe should connect to the chimney such that the flue
pipe extends into, and terminates flush with the inside surface
of the chimney liner. Seal the joint between the pipe and the lin-
ing.
The chimney outlet should be at least two feet above the high-
est point of a peaked roof. All unused chimney openings should
be closed.
Chimneys must conform to local, provincial or state codes, or in
the absence of local regulations, to the requirements of NFPA
2.11 (latest edition) Chimney, Fireplaces, Vents and Solid Fuel
Burning Appliances (in Canada CSA B139)..
NOTE: All furnace models are approved for use with
Type L vent or equivalent.
CAUTION: The furnace must be connected to a flue
having sufficient draft at all times to ensure safe and
proper operation of the appliance.
NOTE: The recommended flue draft pressure is --
0.02 in. W.C. (as measured upstream of the baromet-
ric draft regulator).
The flue pipe must not pass through any floor or ceiling, but
may pass through a wall where suitable fire protection provi-
sions have been installed. Refer to the latest edition of ANSI
NFPA 31 (in the United States, or CAN/CSA B--139 in Canada)
for regulations governing the installation of oil burning equip-
ment.
See Table 4 for burner set-up.
BAROMETRIC DAMPER CONTROL
This device must be used with all chimney and Type L vent sys-
tems. This control (or draft regulator) automatically maintains a
constant negative pressure in the furnace to obtain maximum
efficiency. It ensures that proper pressures are not exceeded.
If the chimney does not develop sufficient draft, the draft control
cannot function properly. The draft regulator, when installed
should be in the same room or enclosure as the furnace and
should not interfere with the combustion air supplied to the
burner.
The control should also be located near the furnace flue outlet
and installed according to the instructions supplied with the
regulator. The flue outlet pressure (measured between the fur-
nace and draft regulator) should be set to --0.02 in. w.c.
FAN AND LIMIT CONTROL
Upflow & Lowboy Models
The L6064A temperature sensitive fan switch is actuated by a
helical bi--metal sensing element enclosed in a metal guard,
and controls the circulating air blower. This provides a delay
between the burner ignition and blower start up to eliminate ex-
cessive flow of cold air when the blower comes on. Blower
shutdown is also delayed to remove any residual heat from the
heat exchanger and improve the annual efficiency of the fur-
nace. Fan settings of 120
°
F to 130
°
F (50
°
C to 55
°
C) and fan
settings of 90
°
F to 100
°
F (32
°
C to 37
°
C) will usually be satis-
factory.
Downflow /Horizontal Models
The L4064W temperature sensitive fan switch contains a
heater--wrapped bi--metal to actuate the fan switch independ-
ent of the temperature at the helical sensing element. The time
from ignition, to the blower on function is approximately 30 sec-
onds. If after 1 minute, the blower has not come on, replace-
ment of the control may be necessary. The blower shutdown is
the same as noted for the L6064A control.
The limit switch performs a safety function and breaks power to
the oil burner primary control, which shuts off the burner if the
furnace over--heats. The limit control is thermally operated and
automatically resets. The limit control is factory installed, pre--
set and is not adjustable.
The limit control and fan control are incorporated in the same
housing and are operated by the same thermal element.
The downflow furnace utilizes an additional auxiliary limit con-
trol which is an automatic reset type.
ELECTRICAL CONNECTIONS
The furnace is listed by the Canadian Standards Association
under the NRTL (North American) Standard. It is factory wired
and requires minimal field wiring. All field wiring should con-
form to the following standards or by local codes, where they
prevail and by In the United States, refer to the National Fire
Protection Association NFPA--70, National Electrical Code
(latest edition), or in Canada, CAN/CSA C22.1 Canadian Elec-
trical Code, Part 1, and with local codes and regulations.
The furnace should be wired to a separate and dedicated cir-
cuit in the main electrical panel; however, accessory equip-
ment such as electronic air cleaners and humidifiers may be
included on the furnace circuit. Although a suitably located cir-
cuit breaker can be used as a service switch, a separate serv-
ice switch is advisable. The service switch is necessary if
reaching the circuit breaker involves becoming close to the fur-
nace, or if the furnace is located between the circuit breaker
and the means of entry to the furnace room.
6
Unitary Products Group
035-14289-000 Rev. A (0701)
AIR FLOW
FAN & LIMIT LOCATION
AIR FLOW
LEFT HORIZONTAL APPLICATION
RIGHT HORIZONTAL APPLICATION
FAN & LIMIT LOCATION
FIGURE 3 - HORIZONTAL APPLICATION
FAN/LIMIT LOCATION
The furnace switch (service switch) should be clearly marked,
installed in an easily accessible area between the furnace and
furnace room entry, and be located in such a manner to reduce
the likelihood that it would be mistaken as a light switch or simi-
lar device.
Accessories requiring 120 VAC power sources such as elec-
tronic air cleaners and humidifier transformers may be pow-
ered from the furnace circuit, but should have their own
controls
Do not use the direct drive motor connections as a power
source, since there is a high risk of damaging the accessories
by exposure to high voltage from the auto--generating wind-
ings of the direct drive motor.
Thermostat wiring connections and air conditioning contactor
low voltage connections are shown in the wiring diagrams on
Page 12. Some micro--electronic thermostats require addi-
tional controls and wiring. Refer to the thermostat manufac-
turer's instructions.
CAUTION: A room thermostat with independent
heat/cool circuit is required.
The thermostat should be located approximately 5 feet above
the floor, on an inside wall where there is good natural air circu-
lation, and where the thermostat will be exposed to average room
temperatures. Avoid locations where the thermostat will be ex-
posed to cold drafts, heat from nearby lamps and appliances, ex-
posure to sunlight, heat from inside wall stacks, etc.
NOTE: Some electronic thermostats do not have ad-
justable heat anticipators. They may have other type
cycle rate adjustments. Follow the thermostat manu-
facturer's instructions.
HUMIDIFIER
A humidifier is an optional accessory available through most
heating supplies outlets. Installation should be carried out in
accordance with the humidifier manufacturer's installation in-
structions. Water or water droplets from the humidifier should
not be allowed to come into contact with the furnace heat ex-
changer. Do not use direct drive motor connections as a source
of power for 120 VAC humidifiers and humidifier transformers.
PIPING INSTALLATION
The entire fuel system should be installed in accordance with
the requirements of ANSI NFPA No. 31 in the United States or
CAN/CSA B--139 in Canada, and local regulations. Use only
an approved fuel oil tanks piping, fittings and oil filter.
Ensure that all fittings used in a copper oil line system are high
quality flare fittings. Do not use compression fittings.
Pressurized or gravity feed installations must not exceed 10
PSIG on the inlet line or the return line at the pump. A pressure
greater then 10 PSIG may cause damage to the shaft seal.
The furnace may be installed with a one pipe system or gravity
feed or lift. The maximum allowable lift on a single line system is
8 ft. Lift should be measured from the bottom (outlet) of the tank
to the inlet of the burner.
Sizing a single line system is complex because of the difficulty
estimating the pressure drop through each fitting, bend and
component in the line. In general, keep single line systems
short as possible. If the furnace is to be installed in a sus-
pended position, a two pipe system may be a better alternative.
Two--stage oil pumps may be used with both single line and
two line systems. Two--stage pumps are available from your
HVAC wholesaler. Table 3 lists allowable line lengths (horizon-
tal plus vertical) for single and two stage oil pumps.
In retrofit applications where an existing oil line system is in
place, a vacuum check will help determine if a two--stage oil
pump is necessary. The vacuum in a system using a single
stage oil pump should not exceed 6" Hg. The vacuum in a sys-
tem using a two--stage oil pump should not exceed 15" Hg. For
additional information, refer to the instruction information sheet
affixed to the oil burner.
Install the oil filter as close to the burner as possible. For further
details of the oil supply tank and piping requirements, please
refer to the instructions and illustrations in the oil burner and oil
pump instructions shipped with the furnace.
OIL FILTER
All fuel systems should include an oil filter between the fuel oil
storage tank and the oil burner. When using an oil burner noz-
zle smaller than 0.65 U.S. Gallons Per Hour, install an addi-
tional 7 to 10 micron filter as close as possible to the oil burner.
OIL BURNER NOZZLES
These furnaces are certified for multiple firing rates, ranging
from 60,000 to 181,000 Btu/h depending on model. By manipu-
lating the oil burner nozzle, flame retention head, static plate
and temperature rise, the furnace may be fired at an ideal rate
for a wide range of structures. Refer to Table 4, and the furnace
rating plate to determine the proper combinations.
CAUTION: Before operating the furnace check
burner alignment with the combustion chamber. The
end cone of the air tube must be centered to the ac-
commodating ring provided in the design of the com-
bustion chamber. Adjust as necessary.
Unitary Products Group
7
035-14289-000 Rev. A (0701)
SINGLE STAGE
2-STAGE
LIFT
3/8" O.D.
TUBING
1/2" O.D.
TUBING
3/8" O.D.
TUBING
1/2" O.D.
TUBING
1
53
100
68
100
2
49
100
65
100
3
45
100
63
100
4
41
100
60
100
5
37
100
58
100
6
33
100
55
100
7
29
100
53
100
8
25
99
50
100
9
21
83
48
100
10
17
68
45
100
12
13
52
42
100
12
—
—
37
100
14
—
—
32
100
16
—
—
27
100
18
—
—
22
88
TABLE 3 - OIL PIPING LENGTHS (FEET)
Set the heat anticipator in the room thermostat to .4
amps. for models P*HBX12F080, P*DHX12F080 &
P*DHX16F120; for other models set heat anticipator at
.2 amps. Setting it lower will cause short cycles. Setting
it higher will cause the room temperature to exceed the
setpoint.
BURNER PRIMARY (SAFETY) CONTROL
The furnace is equipped with a primary combustion control,
sometimes referred to as the burner relay or burner protector
relay, which uses a light sensing device (cad cell) located in the
burner housing, to monitor and control combustion.
Over time, dust or combustion residuals can build up on the
lens of the cad cell impairing its response to the flame. The
cad cell should be checked for cleanliness and proper align-
ment if the primary control frequently shuts down combus-
tion.
COMBUSTION CHAMBER
This furnace is equipped with a high quality cerafelt combus-
tion chamber. It is held in place by a retaining bracket.
CHECK THE ALIGNMENT OF THE COMBUSTION CHAM-
BER AND OIL BURNER BEFORE FIRING. IT IS POSSIBLE
FOR THE COMBUSTION CHAMBER TO SHIFT IF SUB-
JECTED TO ROUGH HANDLING DURING TRANSIT.
The combustion chamber should be inspected for damage or
carbon build up whenever the oil burner is removed for repairs
or routine maintenance.
WARNING: Do not start the burner unless the blower
access door is secured in place.
CIRCULATING AIR BLOWER
These furnaces (with the exception of model P*LBX20F190
which is belt drive) are equipped with direct drive blower sys-
tems. Direct drive blower speed adjustments are not normally
required in properly sized extended plenum duct systems. The
motor RPM and air CFM delivery will vary automatically to ac-
commodate conditions within the usual range of external static
pressures typical of residential duct systems.
Under-sized duct systems may require a higher blower speed
to obtain a reasonable system temperature rise. Some older
duct systems were not designed to provide static pressure.
They typically feature special reducing fittings at each branch
run and lack block ends on the trunk ducts.
These systems may require modification to provide some re-
sistance to the airflow to prevent over-- amping of the direct
drive blower motor. Selecting a lower blower speed may cor-
rect this problem.
Direct drive blower speeds are adjusted by changing the “hot”
wires to the motor winding connections. Please refer to wiring
diagram on Page 12, or the wiring diagram label affixed to the
furnace. THE NEUTRAL WIRE (normally the white wire) IS
NEVER MOVED TO ADJUST THE BLOWER SPEED.
It is possible and acceptable to use a single blower speed for
both heating and cooling modes. The simplest method to con-
nect the wiring from both modes is to use a “piggy--back con-
nector” accommodating both wires on a single motor tap.
8
Unitary Products Group
035-14289-000 Rev. A (0701)
MODEL
OUTPUT
(BTU/H)
BURNER
MODEL
NOZZLE
PUMP
PRESSURE
FLOW RATE
HEAD
STATIC
PLATE
UPFLOW
P*HBX12F08001
60,000
AF76BO
0.50 / 60
°
A
100 PSIG
0.50 GPH
F0
3-3/8"
78,000
AF76BO
0.65 / 60
°
A
100 PSIG
0.65 GPH
F0
3-3/8"
90,000
AF76XN
0.75 / 60
°
A
100 PSIG
0.75 GPH
F3
2-3/4"
100,000
AF76XN
0.85 / 60° A
100 PSIG
0.85 GPH
F3
2-3/4"
P*HBX16F10001
79,000
AF65XN
0.65 / 80
°
A
100 PSIG
0.65 GPH
F3
2-3/4"
90,000
AF65XN
0.75 / 80
°
A
100 PSIG
0.75 GPH
F3
2-3/4"
101,000
AF65XN
0.85 / 80
°
A
100 PSIG
0.85 GPH
F3
2-3/4"
119,000
AF65XN
1.00 / 80
°
A
100 PSIG
1.00 GPH
F3
2-3/4"
LOWBOY
P*LBX12F08001
60,000
AF63B0PWHS
0.50 / 60
°
A
100 PSIG
0.50 GPH
F0
3-3/8"
78,000-
AF63B0PWHS
0.50 / 60
°
A
100 PSIG
0.65 GPH
F0
3-3/8"
90,000
AF63XNPWH
S
0.75 / 60
°
A
100 PSIG
0.75 GPH
F3
2-3/4"
P*LBX16F12001
79,000
AF76XN
0.65 / 80
°
A
100 PSIG
0.65 GPH
F3
2-3/4"
90,000
AF76XN
0.75 / 80
°
A
100 PSIG
0.75 GPH
F3
2-3/4"
101,000
AF76XN
0.85 / 80
°
A
100 PSIG
0.85 GPH
F3
2-3/4"
117,000
AF76XN
1.00 / 80
°
A
100 PSIG
1.00 GPH
F3
2-3/4"
P*LBX16F14501
130,000
AF76YB
1.10 / 70
°
A
100 PSIG
1.10 GPH
F6
2-3/4"
143,000
AF76YB
1.20 / 60
°
A
100 PSIG
1.20 GPH
F6
2-3/4"
P*LBX20F19001
168,000
AF65XO
1.50 / 70
°
B
100 PSIG
1.50 GPH
F12
2-3/4"
181,000
AF65XO
1.65 / 70
°
B
100 PSIG
1.65 GPH
F12
2-3/4"
DOWNFLOW/HORIZONTAL
P*DHX12F0801
60,000
AF76BO
0.50 / 60
°
A
100 PSIG
0.50 GPH
F0
3-3/8"
78,000
AF76BO
0.65 / 60
°
A
100 PSIG
0.65 GPH
F0
3-3/8"
90,000
AF76XN
0.75 / 60
°
A
100 PSIG
0.75 GPH
F3
2-3/4"
TABLE 4 - BECKETT AF OIL BURNER SET-UP
It is also acceptable to connect the selected motor speed with a
pig tail joined to both heating and cooling speed wires with a
wire nut. As a safety precaution against accidental disconnec-
tion of the wires by vibration, it is advisable to secure the wire
nut and wires with a few wraps of electricians tape.
CAUTION: Do not connect power leads between mo-
tor speeds. The neutral wire must always be con-
nected to the motor's designated neutral terminal.
WARNING: Disconnect the power supply to the fur-
nace before opening the blower access door to serv-
ice the air filter, fan or motor. Failure to shut off power
could allow the blower to start unexpectedly, creating
a risk of death or personal injury.
If the joining of the blower speed wiring is done in the furnace
junction box, tape off both ends of the unused wire.
Do not use the blower speed wires as a source of power to
accessories as electronic air cleaners and humidifier
transformers unless it is certain that only one motor speed
will be used. The unused motor taps auto--generate suffi-
ciently high voltages to damage accessory equipment.
MAINTENANCE AND SERVICE
Routine Maintenance By Home Owner
Other than remembering to arrange for the annual professional
servicing of the furnace by the service or installation contractor,
the most important routine service performed by the home
owner is to maintain the air filter or filters. A dirty filter can cause
the furnace to over--heat, fail to maintain indoor temperature
during cold weather, increase fuel consumption and cause
component failure.
The furnace filter(s) should be inspected, cleaned or replaced
monthly. The furnace is factory equipped with a semi--
permanent type filter. If the filter is damaged, replace with filters
of the same size and type. (See Page 5 for listing).
During the routine service, inspect the general condition of the
furnace watching for signs of oil leaks in the vicinity of the oil
burner, soot forming on any external part of the furnace, soot
forming around the joints in the vent pipe, etc. If any of these
conditions are present, please advice your service or installa-
tion contractor.
Annual Service By Contractor
CAUTION: The combustion chamber (firepot) is frag-
ile. Use care when inspecting and cleaning this area.
The heat exchanger should be inspected periodically and
cleaned if necessary. if cleaning is necessary, SHUT OFF
POWER TO THE FURNACE and remove the burner. Using a
stiff brush with a wire handle, brush off scale and soot from in-
side the drum and flue pipe. To clean the radiator, remove the
round covers on the inner front panel to gain access to the
cleaning ports.
When this procedure is done for the first time, carefully cut
away the insulation covering the opening with a sharp knife.
Loosen the nuts on the radiator clean--outs. DO NOT RE-
MOVE THE NUTS. Remove the covers carefully to avoid tear-
ing the gaskets. A wire brush can be used to loosen dirt and
debris on the inside surfaces of the radiator.
Clean out all accumulated dirt, soot and debris with a wire han-
dled brush and an industrial vacuum cleaner. Before replacing
the clean--out covers, inspect the gaskets. If the gaskets are
broken, remove the remnants and replace with new gaskets.
Snug the cleanout covers. DO NOT OVER--TORQUE THE
CLEAN--OUT NUTS. Replace the inner front panel clean--out
covers.
NOTE: A radiator clean--out assembly inadvertently
dropped into the interior of the furnace can usually be
easily retrieved with a magnet on a wire handle or
stout string.
The direct drive blower motor is factory oiled. Under normal op-
erating conditions it does not require oiling for the first two
years. Oil sparingly (a few drops) in each oil port with SAE 20
non--detergent oil. Oiling is most easily done with a “tele--
spout” oilier. This oiler has a long flexible plastic spout. DO
NOT OVER--LUBRICATE. Excess oil causes premature elec-
tric motor failure.
Inspect the blower fan. Clean if necessary.
Oil Burner Maintenance: Follow the instructions of the oil
burner manufacturer. (See oil burner manufacturer's instruc-
tions supplied with furnace). It is advisable to change the oil
burner nozzle and oil filter on an annual basis.
The venting system should be cleaned and inspected for signs
of deterioration. Replace pitted or perforated vent pipe and fit-
tings. The barometric damper should open and close freely.
All electrical connections should be checked to ensure tight
connections. Safety controls such as the high limit controls
should be tested for functionality. The fan control should be
checked to ensure that the “fan off” function continues to stop
the blower fan at temperatures between 90
°
F to 100
°
F.
OPERATING INSTRUCTIONS
Before Lighting
1. Open all supply and return air registers and grilles.
2. Open all valves in oil pipes.
3. Turn on electric power supply
To Light Unit
1. Set the thermostat above room temperature to call for
heat. The burner should start. NOTE: It may be necessary
to press the RESET button on the primary combustion
control relay.
2. After a short period of time, as the furnace becomes warm
enough the act upon the fan control (L6064A), or preheats
the bi--metallic element (L4064W), the blower should
start.
3. Set the thermostat below room temperature. The oil
burner should stop.
4. The air circulation blower will continue to run as long as the
temperature in the furnace is higher than the “FAN OFF”
setting on the fan control. Typical “fan on” values range
from 120° F to 130° F. Typical “fan off” temperatures range
between 90° F and 100° F. The fan control adjustments
may be altered if the air at the room registers is uncom-
fortably high upon blower start up or shutdown, the fan
control settings can be lowered.
5. The adjustments to the fan control settings should be
made by measuring the temperature of the air in the sup-
ply air take--off, or within the first few inches of the supply
air trunk. The side mid point of the transition is usually
ideal, providing that the thermometer probe is beyond the
“line of sight” wherein false readings from radiant heat
could be observed. The system temperature rise, the dif-
ference in temperature between the supply air and return
air, will typically range between 65° F and 70° F.
Unitary Products Group
9
035-14289-000 Rev. A (0701)
To check the operation of the limit switch, shut off power to the
furnace. Temporarily remove the neutral wire from the direct
drive blower motor. Restore the electrical power to the furnace
and set the thermostat above room temperature. After three or
four minutes of burner operation, the limit control should turn
the burner off.
The progress towards a high limit shut down can be monitored
by watching the dial on the fan / limit control. When the limit
function test is complete, shut off electrical power to the fur-
nace, replace the neutral wire to the blower fan motor, then re-
store power. The blower fan will start up immediately. Once the
temperature has dropped, the oil burner will resume and con-
tinue until the thermostat is satisfied. Restore the thermostat
setting to a comfortable temperature.
To Shut Down Unit
1. Set the thermostat to the lowest possible setting.
2. Set the manual switch (if installed) in the Electrical Power
Supply Line to “OFF”.
NOTE: If the furnace is to be shut down for an ex-
tended period of time, close the oil supply valve to the
burner.
OIL BURNER AIR ADJUSTMENT
For complete details, consult the oil burner instruction manual
provided in the furnace documents envelope.
Beckett AF Burner
Adjust the air shutter by loosening the locking screws and mov-
ing the air shutter, and if necessary, the bulk air band.
BURNER ELECTRODES
Adjustment of the electrode tips with respect to each other, the
nozzle, and to the rest of the burner is very important to ensure
smooth start ups and to permit efficient combustion.
Beckett AF Burner Settings
•
Electrode gap: 5/32 inch.
•
Distance above horizontal centerline: 7/16 inch.
•
Distance ahead of nozzle: 1/16 inch.
The distance from the front of the end cone (head) to the face of
the nozzle should be 1--1/8 inches. If a ceramic head is used,
the distance from the end cone to the nozzle face is increased
to 1--3/8 inches.
OIL BURNER SET UP
The burner air supply is adjusted to maintain the fuel to air ratio
to obtain ideal combustion conditions. A lack of air causes “soft”
and “sooty” flames, resulting in soot build--up throughout the
heat exchanger passages. Excess combustion air causes a
bright roaring fire and high stack temperatures resulting in poor
fuel efficiency.
Preparations
Drill a 1/4" test port in the venting, ideally at least 2 diameters
(12") away from the furnace breaching. If venting horizontally
from the furnace, or from the flue pipe elbow if venting vertically
before reaching the furnace (refer to Figure 4).
Before starting the burner, check the burner alignment with the
combustion chamber (firepot), check that the correct nozzle is
tightened into place, and that the burner electrodes are prop-
erly positioned.
Procedure
Start the burner and allow it to run at least ten minutes. Set the
air shutter to give a good flame visually. The air supply to the
burner is controlled by the air shutter on the left side of the
burner, and the bulk air band. To adjust, loosen the bolt on the
movable shutter. Move the shutter gradually until a good flame
(visually) has been achieved. Re--snug the bolt.
Check the initial draft setting as the furnace warms up. The
draft may be measured at the test port. In most cases, the pres-
sure drop between the test port and the oil burner is negligible.
The test port draft reading may be interpreted as the “over fire
draft” reading. The draft should be set to -- 0.02 inches w.c.
Check the oil pump pressure. All furnaces are designed to be
operated at 100 psig.
After reaching steady state, take a smoke test. If not indicating
a trace, set the combustion air controls to provide a trace. In
10
Unitary Products Group
035-14289-000 Rev. A (0701)
FIGURE 4 - TEST LOCATIONS FOR SMOKE TEST
(TOP - HORIZONTAL INSTALLATION)
(BOTTOM - VERTICAL INSTALLATION)
NOTE A: Locate hole at least 6 inches on the furnace side of the draft control.
NOTE B: Ideally, hole should be at least 12 inches from breeching or elbow.
The test port will allow flue gas samples to be taken and stack temperature
to be measured.
most cases, adjustment of the end air shutter will be all that is
necessary.
When the trace smoke has been established, measure the
CO
2
or O
2
in the flue gas. Typically, the CO
2
reading will be ap-
proximately 13% or the O
2
reading approximately 3.3%.
Open the end air shutter (or open the bulk air band if neces-
sary) until the CO
2
reading drops 1 or 2 percentage points, or, if
measuring O
2
content, until the O
2
reading increases 2 or 3
percentage points.
Take another smoke test; it should now be zero smoke. If the
smoke test reads zero, tighten up the end air shutter, and the
bulk air band.
Re--test the draft and the CO
2
or O
2
to be certain that the set-
tings have not shifted.
NOTE: If oily or yellow smoke sports are found on the
smoke test filter paper, it is usually a sign of unburned
fuel. This indicates poor combustion. This type of
problem may be caused by excess draft, excess air,
or contaminated fuel. Do not ignore this indicator.
Stack Temperature
Stack temperature will vary depending on fuel input, circulating
air blower speed and burner set up, etc. In general, stack tem-
perature should range between 350
°
F to 450
°
F, but could be
as high as 550
°
F, assuming that the combustion air approxi-
mately room temperature (65
°
F -- 70
°
F). In general, lower
stack temperature indicates greater efficiency; however, ex-
cessive low stack temperature can lead to condensation form-
ing in the chimney and/or venting. Sulfur and similar
contaminants in the fuel oil will mix with condensation to form
acids. Acids and resultant chemical salts will cause rapid dete-
rioration of the chimney and venting components, and may at-
tack the furnace.
If the flue gases are below the range, it may be necessary to
slow down the blower fan. If the flue gases are above the range,
the blower may require speeding up. Stack temperature varies
directly with the system temperature rise. System temperature
rise is the difference between the furnace outlet temperature
and the furnace inlet temperature as measured in the vicinity of
the connection between the plenum take--offs and the trunk
ducts. Typical temperature rise values range between 65
°
F
and 90
°
F.
If the venting from the furnace to the chimney is long or ex-
posed to cold ambient temperatures, it is advisable to insulate
the venting with a removable, non--combustible, wrap--around
type insulation to reduce stack temperature loss. The vent
should be inspected annually to ensure that it is intact.
FINAL CHECK OUT
Before the final test cycle, carefully examine the complete
heating system for leaks. The hot vent can be checked with a lit
taper for signs of air movement around joints or seams.
Ensure that all safety devices and electrical components have
been set for normal operation. Ensure that all electrical con-
nections are tight and that the wiring is secure.
IMPORTANT:
Please review the following items with the homeowner:
•
where the circuit breaker or fuse is located in the main
electrical panel.
•
where the furnace switch is located, and the switch “on”
and “off” positions if not obvious.
•
where the oil shut--off valve from the oil storage tank is
located.
•
how to operate the thermostat, and other related acces-
sories.
•
how to operate the manual reset button on the primary
control, and especially when not to push the reset button.
•
how and where to visually inspect the venting system for
leaks or other problems.
•
how to inspect, clean and replace the air filter, and other
homeowner maintenance procedures.
•
who to call for emergency service and routine annual
service.
•
the terms and conditions of the manufacturer's warranty
and the contractor's warranty.
Unitary Products Group
11
035-14289-000 Rev. A (0701)
12
Unitary Products Group
035-14289-000 Rev. A (0701)
MODEL
SPEED
TAP
EXTERNAL STATIC PRESSURE, INCHES W.C.
0.20
0.30
0.40
0.50
0.60
P*HBX12F08001
P*DHX12F08001
HIGH
1505
1444
1359
1291
1195
MED HIGH
1423
1381
1291
1220
1144
MED LOW
1170
1144
1118
1063
1005
LOW
813
813
797
763
690
P*HBX16F10001
HIGH
1645
1575
1510
1445
1337
MED HIGH
1540
1500
1420
1350
1266
MED LOW
1145
1135
1115
1095
1035
LOW
745
745
725
715
646
P*DHX16F12001
HIGH
1752
1691
1659
1593
1525
MED HIGH
1454
1454
1417
1379
1300
MED LOW
975
944
912
879
844
LOW
631
593
552
515
486
P*LBX12F08001
HIGH
1917
1885
1820
1717
1608
MED HIGH
1590
1608
1590
1532
1430
MED LOW
1096
1096
1096
1068
1039
LOW
696
647
692
647
598
P*LBX16F12001
P*LBX16F14501
HIGH
1810
1740
1675
1585
1480
MED HIGH
1570
1540
1495
1445
1348
MED LOW
1090
1080
1070
1065
1036
LOW
710
700
690
665
614
P*LBX20F19001
TURNS OPEN
0
2707
2503
2303
2135
1898
1
2372
2233
2085
1870
1594
2
2257
2085
1841
1594
1216
3
2161
1926
1627
1259
795
NOTES:
Airlfow is expressed in standard cubic feet per minute.
Motor voltage at 115V
BLOWER PERFORMANCE
Unitary Products Group
13
035-14289-000 Rev. A (0701)
WIRING DIAGRAM - ALL MODELS
14
Unitary Products Group
035-14289-000 Rev. A (0701)
PROBLEM
POSSIBLE CAUSE
REMEDY
Furnace will not start
Thermostat
not calling for heat
Check thermostat and adjust. Also, check thermostat for accuracy; if it is a
mercury switch type, it might be off level.
No power to furnace
Check furnace switch, main electrical panel furnace fuse or circuit breaker.
Also look for any other hand operated switch, such as an old poorly located
furnace switch which was not removed during furnace replacement.
Thermostat faulty
Check reset button on protector relay. Remove thermostat wires from pro-
tector relay terminals TT. Place a jumper across TT. If furnace starts, replace
thermostat, thermostat sub-base (if equipped), or both.
Protector relay faulty
Check reset button on protector relay. Remove thermostat wires from pro-
tector relay terminals TT. Check for 24v across T.T. If no voltage is present,
check for 115v to protector relay. If 115v is present, replace protector relay.
Photo cell wiring
shorted or room light
leaking into photo cell
compartment
Check photo cell (cad cell) wiring for short circuits. Also check for room light
leaking in to cad cell compartment. Repair light leak if necessary.
Open safety switch
Check for open limit or auxiliary limit, open door switch (if equipped). Also,
check internal wiring connections, loose connectors, etc.
Furnace will not start
without first pushing
protector relay reset
button
(Happens on a
frequent basis)
No fuel oil
Check fuel oil supply. Check that all hand operated fuel oil valves are in the
open position. Fill oil storage tank if necessary.
Clogged nozzle
Replace nozzle with high quality replacement. Use rating plate or table in
this manual as a guide.
Clogged oil pump filter
Replace oil tank filter or in-line filter if used.
low oil pump pressure
Connect pressure gauge to oil pump. Adjust pump pressure, or replace oil
pump if necessary. Ensure that erratic pressure readings are not caused by
defective fuel oil lines.
Air getting into fuel oil
lines, or fuel oil line
dirty, clogged or in
some manner defective
Check oil lines, Replace any compression fittings found with high quality
flared fittings. Check for any signs of oil leaks. An oil leak is a potential
source of air or contaminants.
Defective burner motor
Check burner motor. If burner motor is cutting out on over-load, determine
why. Replace, if necessary
Furnace starts, but
cuts out requiring
manually resetting the
oil protector reset but-
ton
Photo Cell (Cad Cell)
defective
If cad cell is dirty, clean it. (Determine why cad cell is getting dirty). If cad cell
is poorly aimed, realign it. NOTE: The photo cell should have a resistance of
100 K ohms in absence of light; a maximum of 1500 ohms in the presence
of light. Ensure that room light is not leaking into the cad cell compartment.
No fuel oil
Check fuel oil supply. Check that all hand operated fuel oil valves are in the
open position. Fill oil storage tank if necessary.
Clogged nozzle
Replace nozzle with high quality replacement. Use rating plate or table in
this manual as a guide.
Clogged oil filter
Replace oil tank filter or in-line filter if used.
Low oil pump pressure
Connect pressure gauge to oil pump. Adjust pump pressure, or replace oil
pump if necessary. Ensure that erratic pressure readings are not caused by
defective fuel oil line.
Air getting into fuel oil
lines, or fuel oil line
dirty, clogged, or in
some manner defective
Check fuel lines. Replace any compression fittings found with high quality
flared fittings. Check for any signs of oil leaks. any oil leak is a potential
source of air or contaminants.
Defective burner motor
Check burner motor. If burner motor is cutting out on over-load, determine
whey. Replace if necessary.
Water or contaminants
in oil.
Drain fuel oil storage tank, replace fuel oil. (Consult with fuel oil supplier).
Frozen oil line
Gently warm oil line. Insulate oil line. (Outdoor piping size may require in-
creased diameter.
SYSTEM TROUBLESHOOTING
Unitary Products Group
15
035-14289-000 Rev. A (0701)
PROBLEM
POSSIBLE CAUSE
REMEDY
Oil burner sputtering at
nozzle
Electrodes out of adjustment
or defective
Check electrode settings. Check electrodes for dirt build-up or
cracks in porcelain.
Poor transformer high voltage
connections or defective
transformer
Check contacts between transformer and electrodes. If OK, replace
transformer.
Fuel oil filter clogged
Replace fuel oil storage tank filter and/or fuel oil in-line filter
Defective oil pump
Check burner motor/fuel oil pump coupling. Check oil pump pres-
sure. Replace fuel oil pump if necessary.
Fuel oil line partially clogged
or contains air
Bleed air from oil line. If problem persists, replace oil line.
Excessive fuel oil con-
sumption
System temperature rise too
high
System temperature rise should not exceed 85
°
F. Check for
clogged air filters. Check blower fan for excess dirt build-up or de-
bris. Speed up blower fan if necessary.
Blower fan control out of ad-
justment, (fan stops too soon)
Check fan control settings. The fan control is adjusted with a duct
thermometer in the supply air plenum take-off or first few inches of
the supply air trunk duct. The “fan off” setting should be 90
°
- 100
°
F.
Once set, the “fan on” setting is normally adjusted 25
°
-30
°
F higher
than the “fan off” setting.
Fuel oil leak
Check fuel oil line for leaks. Repair or replace if necessary.
Stack temperature too high.
Thermostat improperly ad-
justed or in poor location.
Check stack temperature. Stack temperature will normally range
from 350
°
to 450
°
F. Check draft regulator. Draft should be set to
0.02" WC.
Check thermostat heat anticipator setting against measured amper-
age draw. Increase heat anticipator setting if necessary. If the ther-
mostat is being influenced by drafts, sunlight, duct work, etc,
relocate to a more suitable location.
Too much smoke
Insufficient combustion air
adjustment at oil burner, or
improper draft pressure
Adjust the oil burner combustion air band and draft regulator to gain
the highest CO
2
possible with a Bacharach No.1 smoke.
Heat exchanger partially
clogged
Check for soot build-up in heat exchanger flue passages, especially
in the outer radiator.
Furnace will not warm
home to desired tempera-
ture
Air flow blocked by dirty air
filter
Clean or replace air filter
Thermostat adjustments or
location
Check thermostat heat anticipator setting against measured amper-
age draw. Increase heat anticipator setting if necessary. If the ther-
mostat is being influenced by drafts, sunlight, duck work, etc,
relocate to more suitable location.
Insufficient air flow
Check all dampers. Open closed dampers including registers in un-
used rooms. Check system temperature rise. If temperature rise is
too high, speed up blower fan.
Defective high limit control
Test high limit function of all limit switches. Use a duct thermometer
to assess accuracy of limit control. Check for obstructions to air flow
around limit switch bi-metal elements. Replace control if necessary.
Under-sized nozzle.
Check nozzle. If problem is not caused by air flow problems, use
larger nozzle, if permitted by rating plate.
Blower fan motor stopping in-
termittently on overload
Check blower fan motor amperage draw. Check motor ventilation
ports, clean if necessary. Replace motor if necessary.
Burner motor stopping inter-
mittently on overload
Check burner motor. Replace if necessary.
Home does not heat
evenly
Improper distribution of heat
This is not likely to be furnace problem. Balance duct system.
Supply air temperature too
hot
Air flow blocked or dirty air fil-
ter
Clean or replace air filter.
Insufficient air flow
Check all dampers. Open closed dampers including registers in un-
used rooms. Check system temperature rise. If temperature rise is
too high, speed up blower fan.
Supply air temperature too
cool
Fan control “fan on” setting
too low
Check system temperature rise. Slow down blower fan if necessary.
Excessive duct losses
Check supply air duct work. Seal leaky joints and seams. Insulate
ductwork if necessary.
SYSTEM TROUBLESHOOTING - CONT'D
Subject to change without notice. Printed in U.S.A.
Copyright
by Unitary Products Group 1999. All rights reserved.
035-14289-000-A-1101
Code: EBY, L, F
Supersedes: 035-14289-A-000-300
5005 York
Drive
Norman
OK
73069
Unitary
Products
Group