Water
Heater Pilot Light
Lighting a Gas Water Heater
Replacing
a pilot light
Water heater pilot light or pilot flame is a small gas flame that is
used to ignite gas burner inside the water heater. This small flame is
kept alight constantly so it can light the burner when there is a call.
The gas burner assembly is usually consisted of the pilot
burner, tubing, thermocouple, burner tube and the main burner;
all of them in
charge for lighting the pilot and the water heater. Gas valve is off
course the heart
in this burning operation.
This article will lead your through the useful information about the
pilot,
its role in water heating, how to light pilot light, what to do when
the flame goes out and so on.
The main advantage of water heater pilot light over other alternatives
is its
independence of the electrical system, as it can still light the burner
if there is no electrical power.
The main disadvantages with the pilot flame is its intent to
be constantly on and waste energy and the second problem is
with the flammable
vapors
coming from
flammable liquids to be potentially ignited, unless the unit
is
turned off.
Due to the high concentration vapor problem many water heaters are
equipped
with
FVIR system to shut off the gas
supply to the burner and pilot preventing ignition of vapors in the
area.
Today more and more gas appliances are using a spark (high voltage
electrical arc) from electrodes to ignite the gas or hot
surface vs. the old fashion way when match was used.
How
to Light a Pilot Light - Instructions
Based on the different gas control valve manufacturers, lightning
instructions are slightly different.
The
most common lightning system is piezoelectric
igniter system, consisted of the igniter button,
electrode and wire. The water heater pilot light is ignited by an
electric spark,
generated when the igniter button is pressed. Spark gap distance
measured from electrode tip to pilot is factory set to 0.125 inch and
has to be maintained for successful lighting.
How
to check piezo igniter... check if the spark is present when you
depress the button. Use a sight glass window while viewing the pilot
assembly
to see the action, if it is present.
Here is the step-by-step guide how
to light a hot water heater if the
pilot flame is lit by piezoelectric
igniter:
Remove the outer door panel
Turn the temperature control to its lowest setting
Put the gas knob to the OFF position
Wait for ten minutes to clear out any accumulated gas
Turn the gas control knob to pilot position
(Robertshaw Gas Valve)
Depress and hold down the pilot set button or gas
control knob to let the gas flow to the pilot burner only.
Manually ignite this pilot gas using the piezo
igniter
button by
depressing the igniter until you hear a load click.
Continue to hold the button for up to one minute
after
the pilot light is lit, in order to let the flame heat the thermocouple
and generate sufficient voltage to the gas valve.
Release the knob and it should pop back up.
Turn gas control knob to ON position.
Set thermostat to the desired temperature.
If knob does not pop up when released or pilot will not stay lit after
several tries, turn the gas control knob to OFF position or the main
gas
valve and call service technician.
Air may be present in the gas line and could prevent the pilot from
lightning on initial start-up. Gas line should be purged of air by
qualified person.
Water heater is designed to automatically shut-off if the
pilot light is extinguished for any reason. Thanks to the safety
devices the gas would not keep coming out of the pilot light tube.
Thermocouple is one of these safety elements that prevents the gas from
coming out. Sitting in the pilot flame it is used to determine if the
flame is present. Thermocouple will send the electrical signal
to the gas valve
to shut off the gas supply to the pilot and main burner if the flame is
absent. If the light is extinguished it can take up to 3 min for the
thermocouple to cool sufficiently to close the safety valve.
To re-light the water
heater pilot
light, you have to manually push the button to open the
gas valve. Then you light the pilot light and wait for up to 60
sec
for thermocouple to heat up. Once it is hot, the
thermocouple will generate the electricity that will hold the valve
in open position. Then you can release the button.
The
normal voltage for a properly working thermocouple is between 20 and 30
mv and when installing make the base flush with the base of
the
pilot bracket.
Replacing the Water Heater
Pilot Light and
Tube Assembly
Turn off the gas supply to the water heater by
putting the knob to "OFF" position.
Set the temperature dial on the gas control valve and
thermostat to the lowest setting.
Remove the door panel.
Remove the screws that are securing the manifold
assembly to the combustion chamber.
Disconnect the thermocouple, the tube, igniter
wire, thermal switch and manifold tube and push them slightly down to
release them.
Remove the manifold assembly and release the burner.
Remove the pilot tube from the pilot bracket.
Using the old pilot tube assembly as a guide, bend
the
new tube and thermocouple to match the old ones.
Route the new pilot tube, thermocouple and igniter
wire through the manifold assembly.
Bring everything back in reverse order, secure the
screws, re-install burner assembly and connect feedline.
Follow the instruction located on the lighting
instruction label to resume the operation how to light the water heater
pilot light.