Service Procedures; Removing The Manifold/Burner Assembly; Removing The Burner From The Manifold/Burner Assembly; Replacing The Pilot/Thermopile Assembly - A.O. Smith GCV300 Service Handbook

SERVICE PROCEDURES

Removing the Manifold/
Burner Assembly
1. Turn the gas control/temperature
knob to the "OFF" position (Figure
6 on page 9).
2. Before performing
maintenance, it is important to
turn off the gas supply to the water
heater at the manual gas shut-
off valve (Figure 1, p. 6). This
valve is typically located beside the
water heater. Note the position of
the shut-off valve in the open/on
position, then proceed to turn it
off.
3. With the unit shut-off, allow
sufficient time for the water heater
to cool before performing any
maintenance.
VAC
IGNITER
IGNITER
WIRE
RED WIRE
IGNITER TUBE
WIRE
Figure 15.
4. Remove the outer door.
5. Disconnect the following from the
gas control valve/thermostat: pilot
tube (7/16" wrench), igniter wire
(from the igniter lead wire), and
manifold tube (3/4" wrench). See
Figure 15.
6. Disconnect the white and red
wires from the gas control valve/
thermostat (Figure 15).
needle nose pliers to grip the
connector(s). IMPORTANT: Grip
the connector carefully to prevent
damage. Do not grip or pull the
wires themselves.
7. Grasp the manifold tube and push
down slightly to free the manifold
tube and pilot tube.
8. Remove the screws (1/4" nut
driver) securing the manifold/
burner assembly to the combustion
chamber. (Figure 16.)
9. Carefully remove the manifold/
burner
combustion chamber. BE SURE NOT
any
TO DAMAGE ANY INTERNAL PARTS.
V
Removing the Burner
from
Burner Assembly
Natural Gas (Low Nox) & L.P. Gas
Burner
WHITE
WIRE
1. Take off the burner by removing the
two (2) screws located underneath
the burner (Figure 17.).
2. Check the burner to see if it is dirty
or clogged. The burner may be
cleaned with soap and hot water.
IMPORTANT: DO NOT remove the
orifice.
BURNER SCOOP
(SOME MODELS)
SCREWS (2)
BURNER
Use
(BOTTOM VIEW)
assembly from the
V TAT
V A C
THERMAL
SWITCH
Figure 16.
the Manifold/
PILOT ASSEMBLY
(BOTTOM VIEW)
MANIFOLD
TUBE
Figure 17.
Residential Standard Gas Water Heater Service Handbook • 17
Replacing the
Thermopile Assembly
A. Removing the Old Pilot/
Thermopile Assembly from
the Manifold Assembly
1. Remove the manifold
assembly as described
"Removing the Manifold/Burner
Assembly" section.
2. Remove the burner to access
the pilot/thermopile
Remove and keep the screws
securing the burner to the manifold
(Figure 17.) IMPORTANT: DO NOT
remove the orifice.
3. Remove the screw securing the
pilot/thermopile assembly to the
pilot bracket and keep for reuse
later (Figure 18.)
4. 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. See Figure
18. IMPORTANT: Be careful not
to bend or alter the position of
the pilot tube. It will be used as a
bending template for the new pilot
assembly. Note the placement/
order of the wires in the manifold
component block.
5. Lift the pilot/thermopile assembly
(including the igniter wire) from
the manifold assembly.
PILOT / THERMOPILE
ASSEMBLY SCREW
CONNECTORS
BURNER AND OTHER
FITTINGS NOT SHOW
FOR CLARITY.
IGNITER
WIRE
RETAINER
CLIP
MANIFOLD
COMPONENT
BLOCK RED WIRES TO
PILOT TUBE
MANIFOLD DOOR
Figure 18.
Pilot/
door
in
assembly.