AIC Nesta N 120 FS, Installation And Maintenance Manual, Page: 48 / 72

I-48
A-070336_EN • Rev. A
M
aintenance
Removing and Installing the Fan and Air
Adapter Assembly
Conditions:
Tools and material:
î
Wrench, hex head, sizes 4 and 6
î
Wrench, flat, sizes 8 and 13
î
Torque wrench
î
Protective gloves
î
Face mask
î
Loctite 577 - thread sealant
Removal Procedure:
1. Disconnect all connectors and ground wires
from the electrodes, the burner plate temper-
ature limit switch, the fan and the gas valve.
2. Disconnect the air hose from the gas valve.
3. Wearing protective gloves and a face mask,
remove insulation from the upper plate. Re-
tain for reinstallation.
4. Disconnect the air inlet duct (
9
) from the air
adapter (
8
).
5. Release four screws (and washers -
N 120
FS to N 200 FS
) (
4
) securing the gas valve (
3
)
to the gas pipe inlet flange. Retain hardware
and O-ring, as required, for reinstallation.
When removing the O-ring, check its
general condition. Discard and re-
place the O-ring if it is dirty or cracked.
6. Release four screws (and washers -
N 120 FS
to N 200 FS
) (
2
) securing the gas valve (
3
) to
the gas pipe outlet flange.
7. Remove the gas valve (
3
) and hardware (
2
).
Retain hardware and O-ring, as required, for
reinstallation.
When removing the O-ring, check its
general condition. Discard and re-
place the O-ring if it is dirty or cracked.
8. Release four nuts (
7
) securing the fan and air
adapter assembly (
1
) to the burner assembly.
9. Remove the fan and air adapter assembly (
1
)
and its hardware. Retain for reinstallation.
OFF
i
i
10. Remove the fan gasket (
6
). Discard.
11. Remove the electrodes, as required, refer to
“Removing and Installing the Ignition and
Ionization Electrodes” on page I-50.
12. Remove the burner, as required, refer to
“Removing and Installing the Burner” on
page I-51.
13. Clean the combustion chamber, as required,
refer to “Checking and Cleaning the Com-
bustion Chamber” on page I-52.
Installation Procedure
1. Apply sealant on the threads of the four fan
plate studs (
5
).
2. Install fan and air adapter assembly with a
new gasket (
6
) on fan plate using four re-
tained nuts (
7
).
3. Tighten the nuts (
7
) in a circular pattern,
torquing at 4 Nm (
N 120 FS
) or 6 Nm (
N 160
FS to N 250 FS
).
4. Install O-ring and fasten the gas valve (
3
) to
the gas pipe outlet flange using four retained
screws (and washers -
N 120 FS to N 200 FS
)
(
2
). Torque screws at 3.5 Nm (
N 120 FS - N 160
FS
) or 6 Nm (
N 200 FS - N 250 FS
).
5. Install O-ring and fasten the gas valve (
3
) to
the gas pipe inlet flange using four retained
screws (and washers -
N 120 FS to N 200 FS
)
(
7
). Torque screws at 3.5 Nm (
N 120 FS - N 160
FS
) or 6 Nm (
N 200 FS - N 250 FS
).
6. Connect the air inlet duct (
9
) to the air adapt-
er (
8
).
7. Wearing protective gloves and a face mask,
Install insulation on the upper plate
8. Reconnect all connectors to the electrodes,
burner plate limit switch, gas valve and fan.
Follow-on task(s):
1. Close all panels, refer to “Removing and In-
stalling the Access Panels” on page I-27.
2. Restart the boiler, as required, refer to “Re-
starting after Maintenance” on page I-46.