Piezoelectric Igniter System; Testing The Igniter System; Removing And Replacing The Gas Control Valve/Thermostat - A.O. Smith GAS WATER HEATER Installation Instructions And Use & Care Manual

7. Connect the white (-) thermopile wire to the gas control
valve/thermostat, then connect the red thermal switch
wires to the thermal switch on the manifold door.
(Figure 23).
8. Reconnect the igniter wire (Figure 22).
9. Turn on the gas supply to the water heater at the manual
gas shut-off valve (Figure 3).
10. Follow the lighting instructions on the front of the water
heater. With the main burner lit, check for leaks at
the manifold and pilot connections by brushing on an
approved noncorrosive leak detection solution. If such
a solution is not available, use a mixture of hand dish
washing soap and water (one part soap to 15 parts
water) or childrens' soap bubble solution. Bubbles
forming indicate a leak. Correct any leak found.
11. Verify proper operation, then replace the outer door.
MANIFOLD TUBE

Piezoelectric Igniter System

The piezoelectric igniter system consists of the igniter
button, electrode, and wire. The pilot is ignited by an
electric spark generated when the igniter button is pressed.
(See Figure 30).
VAC
ELECTRODE
WIRE TO ELECTRODE
IGNITER BUTTON

Testing the Igniter System

Turn off the gas to the water heater at the manual gas
shut-off valve. Watch the electrode tip while activating the
igniter. A visible spark should jump from the electrode. To
avoid shock, do not touch the burner or any metal part
on the pilot or pilot assembly. If no spark is visible, check
the wire connections and make sure the electrode is not
broken. Replace the igniter if defective. Dirt and rust on the
pilot or electrode tip can prevent the igniter spark. Wipe
clean with a damp cloth and dry completely. Rust can be
removed from the electrode tip and metal surfaces by
lightly sanding with an emery cloth or fine grit sandpaper.
CLOSE-UP INSIDE VIEW OF
THE COMBUSTION CHAMBER.
SLOT
TIP
BRACKET
FIGURE 29.
THERMOPILE
PILOT
PILOT/
THERMOPILE
BRACKET
FIGURE 30.
Removing and Replacing the Gas Control
Valve/Thermostat
IMPORTANT: This water heater has a resettable thermal
switch installed. Do not attempt to disable or modify this
feature in any way. Use only factory authorized
replacement parts.
Removing the Gas Control Valve/Thermostat:
1. Turn the gas control/temperature knob to the "OFF"
position (Figure 19A).
2. Turn off the gas at the manual shut-off valve on the gas
supply pipe (Figure 3).
3. Drain the water heater. Refer to the section of "Draining
and Flushing" and follow the procedure.
4. Disconnect the igniter wire from the igniter lead wire. Use
needle nose pliers to disconnect the red (+) and white (-)
thermopile wires. Disconnect the pilot tube (7/16" wrench)
and manifold tube (3/4" wrench) at the gas control valve/
thermostat (Figure 22). NOTE: L.P. Gas systems use
reverse (left-hand) threads on the manifold tube.
5. Refer to "Gas Piping" (Figure 3) and disconnect the
ground joint union in the gas piping. Disconnect the
remaining pipe from the gas control valve/thermostat.
6. To remove the gas control valve/thermostat, thread
a 4" section of gas pipe into the inlet and use it to turn
the gas control valve/thermostat (counterclockwise.)
Do not use a pipe wrench or equivalent to grip body.
Damage may result, causing leaks. Do not insert
any sharp objects into the inlet or outlet connections.
Damage to the gas control valve/thermostat may
result.
Replacing the Gas Control Valve/Thermostat:
To replace the gas control valve/thermostat, reassemble
in reverse order. When replacing the gas control valve/
thermostat, thread a 4" section of gas pipe into the inlet and
use it to turn the gas control valve/thermostat (clockwise).
DO NOT OVER TIGHTEN; damage may result.
• Be sure to use approved Teflon® tape or pipe joint
compound on the gas piping connections and fitting on
the back of the gas control valve that screws into the
tank.
• Be sure to remove the pilot ferrule nut from the new gas
control valve/thermostat.
• Turn the main gas supply on and check the gas supply
connections for leaks. Correct any leak found.
Next, light the pilot and main burner, then check the
manifold tube and pilot tube connections for leaks.
Correct any leak found.
Use an approved noncorrosive leak detection solution.
If such a solution is not available, use a mixture of
hand dish washing soap and water (one part soap
to 15 parts water) or childrens' soap bubble solution.
Bubbles forming indicate a leak.
• Be sure tank is completely filled with water before
lighting and activating the water heater. Follow the
"Lighting Instructions" on page 21.
• If additional information is required, reference
the number on the cover of this manual for service
information.
®
TEFLON is a registered trademark of E.I. Du Pont De Nemours and Company
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