SERVICE AND TECHNICAL SUPPORT MANUAL
Gas Furnace: N9MSB
Specifications subject to change without notice.
18
440 04 4412 01
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
,
.
Figure 10
Igniter Position
−
Top View
A11405
2-1/2-in.
(64.4)
1-1/4-in.
(31.8)
Figure 11
Igniter Position
−
Side View
A12392
2
−
in.
(2.5 mm
3/8
−
in.
3/16
−
in.
, +0.8 -1.5)
(50 mm)
(9.6 mm)
(4.6 mm)
3/32
−
in., +1/32 -3/64-in.
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.
!
WARNING
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal injury,
death, and/or property damage.
Never purge a gas line into a combustion chamber. Never
test for gas leaks with an open flame. Use a commercially
available soap solution made specifically for the detection of
leaks to check all connections. A fire or explosion may result
causing property damage, personal injury or loss of life.
14. Check for gas leaks with a commercially available soap
solution made specifically for the detection of leaks.
15. Turn gas on at electric switch on gas valve and at
external shut-off or meter
16. Turn power on at external disconnect, fuse or circuit
breaker.
17. Run the furnace through two complete heating cycles to
check for proper operation
18. Install control door when complete.
Servicing Hot Surface Igniter
The igniter does
NOT
require annual inspection. Check igniter
resistance before removal. Refer to
,
and
.
1. Turn off gas and electrical supplies to furnace.
2. Remove control door.
3. Disconnect igniter wire connection.
4. Check igniter resistance. Igniter resistance is affected by
temperature. Only check resistance when the igniter is at
room temperature.
a. Using an ohm meter, check resistance across both
igniter leads in connector.
b. Cold reading should be between 40 ohms and 70
ohms.
5. Remove igniter assembly.
a. Using a 1/4
−
in. driver, remove the two screws
securing the igniter mounting bracket to the burner
assembly (See
)
b. Carefully withdraw the igniter and bracket assembly
through the front of the burner assembly without
striking the igniter on surrounding parts.
c. Inspect igniter for signs of damage or failure.
d. If replacement is required, remove the screw that
secures the igniter on igniter bracket and remove the
igniter.
6. To replace igniter and bracket assembly, reverse items
5a through 5d.
7. Reconnect igniter harness to the igniter, dressing the
igniter wires to ensure there is no tension on the igniter
itself. (See
8. Turn on gas and electrical supplies to furnace.
9. Verify igniter operation by initiating control board self
−
test
feature or by cycling thermostat.
10. Replace control door.
Flushing Collector Box and Drainage System
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
1. Turn off gas and electrical supplies to furnace.
2. Remove control door.
3. Disconnect pressure switch tube from pressure switch
port.
NOTE
: Ensure the pressure switch tube disconnected from the
pressure switch is higher than the collector box opening or
water will flow out of tube.
