Flame Sense/Hot Surface Igniter Removal / Replacement - A.O. Smith 12 40GPC T 100 Service Handbook

FLAME SENSE/HOT SURFACE IGNITER REMOVAL / REPLACEMENT

Important: Use only factory authorized replacement
parts. If you lack the necessary skills to properly
perform the installation, you should not proceed, but
get help from a qualified service technician.
Tools required: 3/4" Open-End Wrench or Crescent
Wrench, Phillips Head Screwdriver, Ratchet with 1/4"
socket or 1/4" Nut Driver.
Replacing the Flame Sense/Hot Surface Igniter
Assembly:
1. Set the gas control valve/thermostat to its lowest
setting by pressing the "COOLER" and "HOTTER"
buttons together at the same time holding for 1
second. Then press the "COOLER" button to the
lowest setting (Figure 89).
2. Turn gas control switch to the "OFF" position
(located right side of the gas control valve/
thermostat) and turn off the gas supply to the unit
(Figure 90).
3. Disconnect the electric connection by unplugging
the transformer from the wall outlet (Figure 90).
4. Remove the manifold cover/ outer door from the
unit by depressing on the lower portion and
pulling outward.
5. Remove the inner door/manifold/burner assembly.
See Removing Inner Door/Manifold/Burner
Assembly, (page 41) (Figure 91).
6. Lift the retainer clip straight up from the back of
the manifold component block (using a flat-blade
screwdriver), then remove the manifold component
block from the manifold door (Figure 92).
7. Remove and keep the screw securing the flame
sense/hot surface igniter assembly (Figure 92).
8. Remove and discard the old flame sense/hot
surface igniter assembly.
9. Route the new flame sense/hot surface igniter
connector wire through manifold/burner door
opening as shown in figure 92. Secure the
assembly to the bracket ussing screw removed
earlier.
10. Reposition the manifold component block in the
manifold door opening and secure it with the
retainer clip.
11. Install inner door/manifold/burner assembly,
(see page 42).
12. Restart the water heater by following the
directions on the "Lighting and Operating
Instructions" label located on the front of the water
heater.
13. Upon verifying proper operation of the water
heater, replace the manifold cover/outer door.
Figure 89.
HOTTER
Figure 90.
Figure 91
INNER DOOR/
MANIFOLD/BURNER
ASSEMBLY
Figure 92
Screw
Manifold Component
Block
43
g
COOLER
Electronic Control Display
ON
OFF
ON/OFF
SWITCH
UNPLUGGED
Retainer Clip
SLOT
BURNER'S
TIP END
TAB
Flame Sense/
Hot Surface
Igniter Assembly