A.O. Smith ATI-140H-N Service Handbook page 38

6.1 Disconnect fastener 14-22
(item 458, page 70).
6.2 Remove two heaters and
clips (located at top and
bo om of tube):
◦
Items 413 & 451, p. 70.
◦
Items 414 & 451, p. 70.
See also Figure 28.
6.3 Slide the cold connec on tube
downward and remove it.
7. Remove the igniter assembly:
7.1 Remove the screw that
secures the igniter assembly
(See Figure 24, page 35.)
7.2 Disconnect the igniter
wire at the igniter rod wire
connec on (Figure 24, page
35).
8. Disconnect the blue wires from
the high limit switch. See "High
Limit Switch (Heat Exchanger),"
Figure 24, page 35.
The wires are locked onto the
connectors. Pinch the flat sides
on each connector to release it.
Flame Rod Wire Connector:
To remove, pinch flat sides at end
with your finger nails, then slide
connector off the spade.
Figure 26.
38 • Condensing Models: On-Demand Water Heater Service Handbook
9. Remove the Gas Valve and
Manifold Plate Assembly:
9.1 Unplug wire connectors
from the air/fuel ra o rod
(AFR), fl ame rod, and igniter.
See Figure 26.
9.1 Remove the screws that
secure the green ground
wires to the manifold plate.
9.2 Remove the screws that
secure the manifold plate
(Figure 24, page 35).
IMPORTANT: Remove only
the screws along the outside
edges of the manifold plate.
See Figure 27.
•
DO NOT remove the
screws securing the
manifold plate to the gas
valve.
•
DO NOT remove the
screws along the interior
of the manifold plate.
9.3 Remove the screw on the
le side of the gas valve that
secures the power cord.
9.4 Disconnect the air tube off
the le side of the gas valve.
(See page 42, Figure 37.)
9.5 Disconnect the connector
on the right side (blue wires)
which goes to the overheat
cutoff fuse (Figure 24, page
35).
9.6 Remove the brass screw
securing the gas valve to the
gas connec on. The screw
is located at the bo om,
right-hand side of the gas
valve; see Figure 24, page
35.
9.7 Li the manifold plate/
gas valve assembly upward
to remove it from the gas
inlet connec on. (The gas
valve and manifold are s ll
connected together.)
You may need to twist
the gas valve/manifold
assembly slightly.
9.8 Unplug the wire connectors
at the solenoid valve
(SV3); the solenoid valve
is a ached to the corner
of the manifold plate. If
necessary, see Figure 20,
page 30.
9.9 Disconnect the solenoid
connectors (Item 707,
p. 69) from the gas
valve. (There are three
connectors.)
9.10 Disconnect the propor onal
gas valve connector (item
711, p. 69) from the
assembly.
9.11 Inspect the gaskets on the
manifold plate for any tears.
If compromised, replace with
Manifold Screws:
• DO NOT remove the screws
shown below (indicated by
white, crossed-out circles).
• Remove the remaining
screws along the outside
edge (except as indicated).
Figure 27.