A.O. Smith ATI-140H-N Service Handbook page 31

4.6 Remove the 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.
4.7 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.
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 21.
Damper
Burner
Assembly
Figure 22.
4.8 Unplug the wire connectors
at the solenoid valve (SV3);
the solenoid valve is a ached
to the corner of the manifold
plate. See Figure 20.
4.9 Unplug the propor onal gas
valve connector (item 711,
page 69).
4.10 Disconnect the solenoid
connectors (Item 707, p.
69) from the gas valve.
(There are three connectors.)
4.11 Inspect the gaskets on the
manifold plate for any tears.
If compromised, replace with
part number 319143-044
(item 113) and/or 319143-
045 (item 114). See page
69.
4.12 Inspect the o-ring (item 151,
p. 69) and gas inlet ring
(item 119, p. 69) on the
gas connec on for cuts or
breaks.
If damaged, replace with part
number 319143-057 (item
151) and/or 319143-049
(item 119). See page 69.
5. Remove the burner assembly
according to the following steps.
(See Figure 22.)
5.1 Remove the pan-head
Phillips screws holding the
burner to the combus on
chamber. There are several
at the top of the burner and
two more at the bo om
(toward back of combus on
chamber). If the screws at
the bo om are diffi cult to
remove, li the burner while
turning the screws.
Condensing Models: On-Demand Water Heater Service Handbook • 31
5.2 Note the orienta on of the
damper, then remove the
damper (item 112, p. 69).
See Figure 22.
5.3 Remove the burner assembly
as described below:
5.3.1 Grasp an oval air vent on the
front of the burner (at the
edge on either side).
5.3.2 Pull fi rmly while pushing
on the bo om of the
combus on chamber to
provide leverage.
5.3.3 Repeat on the opposite side
to loosen the assembly.
5.3.4 Pull from the center. It
should slide out easily.
5.4 Inspect the gasket. Minor
surface tears are acceptable.
If the gasket shows major
separa ons, replace the
gasket before the unit is
returned to service.
6. Clean the burner:
•
Use a safe degreaser.
•
Protect the burner gasket from
direct water pressure. If the
gasket is damaged in any way,
contact technical service for
further assistance.
6.1 Saturate the burner with
the cleaning solu on (from
top, down through slots, and
openings in front of burner).
Con nue un l burner is
completely wet.
6.2 Wait for fi ve minutes.
6.3 Set the burner in a sink in
its normal, upright posi on
and wash the burner with a
high fl ow of water. Ensure
that the water fl ows down