81
ELECTRICAL SHOCK AND FIRE HAZARD
Failure to follow this warning could result in personal injury,
death, and/or property damage.
Turn off the gas and electrical supplies to the furnace and
install lockout tag before performing any maintenance or
service. Follow the operating instructions on the label
attached to the furnace.
!
WARNING
FLAME SENSOR
(BELOW BURNER)
FLAME ROLLOUT
SWITCH
BRACKET, IGNITER
IGNITER
BURNER SUPT. ASSY
BURNER ASSY
A11403
Fig. 66 -- Burner Assembly
Refer to Fig. 66.
1. Disconnect power at external disconnect, fuse or circuit
breaker.
2. Turn off gas at external shut-off or gas meter.
3. Remove control door and set aside.
4. Turn electric switch on gas valve to OFF.
5. Disconnect the gas pipe from gas valve and remove pipe
from the furnace casing.
6. Remove individual wires from terminals on gas valve.
7. Disconnect Hot Surface Igniter (HSI) wires from HSI.
8. Disconnect Flame Sensor wire from Flame Sensor.
9. Support the manifold and remove the 4 screws that secure
the manifold assembly to the burner assembly and set aside.
Note the location of the green/yellow wire and ground ter-
minal.
10. Inspect the orifices in the manifold assembly for blockages
or obstructions. Remove orifice and clean or replace orifice.
11. Remove the four screws that attach the top plate of the cas-
ing to the furnace.
12. Raise top plate up slightly and prop it up with a small piece
of wood or folded cardboard.
13. Support the burner assembly and remove the screws that at-
tach the burner assembly to the heat exchanger cell panel.
14. Remove wires from both rollout switches.
15. Slide one--piece burner out of slots on sides of burner as-
sembly.
16. Remove the flame sensor from the burner assembly.
17. (Optional) Remove the Hot Surface Igniter (HSI) and
bracket from the burner assembly.
18. Check igniter resistance. Nominal resistance is 40 to 70
ohms at room temperature and is stable over the life of the
igniter.
19. Clean burner with a brush and a vacuum.
20. Clean the flame sensor with fine steel wool (0000 grade).
Do not use sand paper or emery cloth.
To reinstall burner assembly:
1. Install the Hot Surface Igniter (HSI) and bracket in burner
assembly.
2. Install flame sensor on burner.
3. Align the edges of the one-piece burner with the slots in the
burner assembly and slide the burners forward until they are
fully seated in the burner assembly.
4. Align the orifices in the manifold assembly with the support
rings on the end of the burner.
5. Insert the orifices in the support rings of the burners.
NOTE
: If manifold does not fit flush against the burner, do not
force the manifold on the burner assembly. The burners are not
fully seated forward in the burner assembly. Remove the manifold
and check burner positioning in the burner assembly assembly
before re-installing the manifold.
6. Attach the green/yellow wire and ground terminal to one of
the manifold mounting screws.
7. Install the remaining manifold mounting screws.
8. Check the igniter alignment. See Fig
.
67, 68 and 66.
9. Attach the wires to the roll-out switches.
10. Align the burner assembly with the openings in the primary
cell inlet panel and attach the burner assembly to the cell
panel.
11. Connect the wire for the flame sensor.
12. Connect the wire for the Hot Surface Igniter.
NOTE
: Use propane-resistant pipe dope to prevent leaks. Do not
use Teflon tape.
13. Install the gas pipe to the gas valve.
2-1/2-in.
(64.4)
1-1/4-in.
(31.8)
A11405
Fig. 67 -- Igniter Position -- Top View
2
ï
in.
2.5 mm
3/8
ï
in.
3/16
ï
in.
+0.8
ï
1.5 mm
50 mm
9.6 mm
4.6 mm
1/10
ï
in.
+ 1/32
ï
1/16
ï
in.
L12F041
Fig. 68 -- Igniter Position -- Side View
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal injury,
death, and/or property damage.
Never purge a gas line into a combustion chamber. Never test
for gas leaks with an open flame. Use a commercially available
soap solution made specifically for the detection of leaks to
check all connections. A fire or explosion may result causing
property damage, personal injury or loss of life.
!
WARNING
