Residential Standard Gas Water Heater Service Handbook • 13
C
OMMON ISSUE
S
Fire and Explosion Hazard
WARNING! Do not
attempt to light the water
heater if flammable vapors or liquids
are present. Do not store or use
gasoline or other flammable vapors
and liquids in the vicinity of this or any
other gas appliance. Storage of or use
of gasoline or other flammable vapors
or liquids in the vicinity of this or any
other appliance can result in serious
injury or death.
No Hot Water
If water is not being heated, check the
following:
1.
Look at the gas control valve/
thermostat. Is it flashing? If so,
solutions for restoring hot water are
listed below. See also “Diagnostic
Flash Codes” on page 10.
1 Flash
Normal Operation
(This code may occur after you
relight the pilot.)
Once the water heater has
completed a heating cycle, it should
provide an adequate amount of
hot water. If it does not, see “Not
Enough Hot Water.” If the pilot
lights for a while, then goes out, see
“0 Flashes (LED not lit)” on page 10.
2 Flashes
Thermopile voltage is low
Possible causes/solutions:
• Thermopile is getting weak.
• Check wiring and connections.
• If necessary, replace the
thermopile. See “Replacing
the Pilot/Thermopile
Assembly” on page 17.
4, 5, or 7 Flashes
If you observe one of these
flash codes, refer to “Diagnostic
Flash Codes” on page 10.
8 Flashes
Power Off Failure
Often, this error can be cleared
by turning the pilot off, letting
it cool down for ten minutes,
then relighting it according to
the lighting instructions. See
“8 Flashes” on page 10.
2. If the status light is not lit, see
“0 Flashes (LED not lit),” page 10.
That section will help you investigate
causes related to the thermal switch
(TCO), spark ignition, gas pressures,
and thermopile connections.
NOTE:
The pilot must be lit for
the status light (LED) to flash.
Heat from the pilot causes the
thermopile to generate voltage.
Without this voltage, the gas control
valve/thermostat cannot operate.
Remember: it may take up to 90
seconds to heat the thermopile
enough to power the status light.
3. If you completed step 2 and
the pilot will not light, check for
air in the gas line. (This is fairly
common with recent work/new
installations.) If there is air in
the gas line, bleed the line as
necessary. Make sure to hold the
gas control knob in fully and hold it
in. In most cases, energy efficient
pilot orifices are so small that it
may be difficult to clear the air by
holding the knob in.
When you are finished, try to light
the pilot. (Follow the lighting
instructions on the water heater.)
Remember to hold the control
knob in for at least 90 seconds so
the pilot can heat up.
Did the pilot light? If it did, check
the following:
A. If the pilot did not light, replace
the pilot. (The entire pilot/
thermopile assembly must be
replaced). The most likely cause
is contamination in the pilot
tube.
A. If the pilot is lit and the status
light is flashing, refer to
“Diagnostic Flash Codes” on
page 10.
B. If the pilot is lit, but the status
light did not start flashing, check
the thermopile (p. 12). If its
output is 350 mV or less, it must
be replaced. If its output is
greater than 350 mV, replace the
gas control valve/thermostat.
Not Enough Hot Water
Check the following if the water is not
hot enough or if the hot water runs out
too quickly:
Possible causes
• Lower seasonal water temperatures
• Faulty shower control or faucet
valve
• Thermostat is set too low
• Increased hot water usage
• Water heater is too small to meet
demand
• Reversed plumbing connections
• Plumbing system leak
• Sediment buildup in the tank
Verify the water temperature at
the temperature/pressure relief
valve. Check the mixing valve/
shower control settings. Also
check for leaks, heavy usage, and
extremely cold incoming water.
In all cases, clean the filter and
flame arrestor (p. 18), then
conduct a draft test (p. 11).
A description of each cause and its
solution(s) is listed below.
Lower Seasonal Water Temperatures
In some areas, water coming into the
tank is much colder during winter
COMMON ISSUES
