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Troubleshoot water heater pilot light
pilot light troubleshoot
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Back to 14 things for troubleshooting gas water heater
10) troubleshoot thermocouple- thermopile, pilot light
Pilot light heats the thermocouple or thermopile, producing small millivoltage of electricity that travels to the gas control valve along the copper pilot tube. If the pilot light goes out, the lack of electric current shuts down the gas control valve and pilot light needs to be lit again. Older model gas water heaters required a long match and patience to relight pilot, while more recent water heaters are required to have sealed combustion chamber and use a piezo igniter to light pilot.
Thermocouple and thermopile are different. Thermopile is basically several thermocouples combined and produces more current than thermocouple. Thermocouples are used with older-style mechanical gas control valves that have a round dial on front. Thermopiles produce enough current to power small circuit board and are used with modern electronic gas control valves.

Causes for pilot outage:

Backdraft from shared vent and wind coming down the flue can blow out the pilot. Dirty combustion parts and need for maintenance. Bad thermopile or thermocouple. Misaligned thermocouple. Thermocouple too tight of too loose on gas control valve. Tripped TCO, thermal cut off. Not enough fresh air. Bad gas control valve and ECO can cause pilot outage.  Improper venting, clogged vent, obstructed vent. Tripped FV flammable vapor system. No gas, or not enough gas.
Problem and action for pilot light issues:
Pilot flutters and goes out when gas valve moved to heat: FV lockout, Bad gas control valve
Pilot light gets small when gas valve moved to heat: Low gas pressure, Bad gas control valve
Pilot light burns blue but flame is small: Low gas pressure,  Clean pilot tube and combustion chamber, Wrong orifice installed
Pilot light burns yellow instead of blue: Check proper venting, Low gas pressure, Clean pilot tube and combustion chamber
Pilot constantly or periodically goes out: Check proper venting, Low gas pressure or inconsistant gas supply, Insufficient air supply clean the FV screen, Open windows and doors, Clean pilot tube and combustion chamber, Replace thermocouple, Bad gas control valve, Backdraft down the flue caused by shared vent or household vent fans, Undersized gas supply caused by too many gas appliances.
Pilot will not lightLow gas pressure, Improper lighting sequence, Clean pilot tube and combustion chamber, Replace thermocouple, Bad gas control valve
Pilot will not stay lit:  Poor thermocouple connection at gas valve, misaligned thermocouple, defective thermocouple/ replace, ECO tripped on gas control valve or defective gas valve, TCO is tripped
Causes for pilot outage:
Backdraft from shared vent and wind coming down the flue can blow out the pilot. see section 11 for venting. Dirty combustion parts and need for maintenance can also cause outage. see section 7. Bad thermopile or thermocouple. Misaligned thermocouple can also cause outage. Modern water heaters have solved the misalignment problem with fixed positioning and 1-piece replacement for combustion parts. see section 7. Bad gas control valve can cause pilot outage. see section 6.

Look upward, and to one side, through sight glass to see that pilot flame is lit and clear blue color.

Pilot light troubleshoot:
Clean the air intake, and get more fresh air to unit.
 Push in TCO located on front of combustion chamber.
Pilot troubleshoot resources
Test thermocouple
How to light gas water heater
Pilot light goes out
Burner goes out when control knob turned to ON
Pilot light will not stay lit/ pdf
Pilot outage/ pdf
Pilot problem or ECO or gas control?
Wind blows out pilot light
Pilot light or thermocouple?
Negative pressure blows out pilot
Pilot orifice
Pilot tube orifice
Clean with compressed air or carburetor cleaner
Do not rub with rag, or tube can clog
Pilot troubleshoot resources con't
Standing pilot light maintenance
Attic Ventilation and Pilot Outage
Pilot outage and negative pressure
Pilot light maintenance/ pdf
Ventilating tight-house/ pdf
Pilot light troubleshoot
pilot assembly
Buy:
Rheem Pilot assembly
AO Smith Pilot
Reliance Pilot
Kenmore Pilot
Bradford White Pilot
Gas water heater
Gas water heater
How to remove burnerPilot-outage-troubleshooting.pdf
Avoid Corrosive environments
Exposure to corrosive environments such as pool chemicals, process chemicals, bleach can damage burner parts.
Air is drawn into water heater, and if air contains trace amounts of chemical, or chemicals are burned in the flame, this will damage water heaters over time, and shorten life of water heater
Remove chemicals from same room as water heater.
-Chemicals that will corrode water heater parts and vent pipe include: 'Spray propellants, cleaning solvents, refrigerants, swimming pool chemicals, calcium and sodium chloride, household bleach, waxes and process chemicals ... all these chemicals are corrosive at very low levels with no odor."
Read Bradford White Pdf pg2-8   
Read Rheem pdf
Avoid corrosive atmospheres

piezo igniter
Buy:
AO Smith igniter
Rheem igniter
Reliance igniter
Piezo igniter
Today's water heaters have igniter to send spark to pilot light to start flame.
Older water heaters have open combustion chamber and pilot was lit with a match ... the piezo igniter helps prevent explosion into someone's face, or ignition of flammable vapors in the room caused by open flame.
The igniter is part of the FV flammable vapor prevention system where the combustion chamber is sealed so flames cannot easily travel from inside combustion chamber out into surrounding room.

How to test piezo igniter
How to check the igniter
Electronic spark troubleshoot
Troubleshoot hot surface ignition
Hot surface igniter troubleshoot
Power vent hot surface ignition
How to check ignition cable and spark ignitor
"This procedure will expose you to 10,000 volts of electrical energy. When performing these steps do not touch bare or exposed wiring. Make sure the heater is turned off when servicing or inspecting the spark ignition system.
1. Make sure ignition cable does not contact any metal surfaces, is no more than 36 inches long, and connections to the ignition control module and ignitor are clean and tight.
2. On power vents and flue damper heaters: Check ignition system grounding. Nuisance shutdowns are often caused by a poor or erratic ground. Check for good metal to metal contact between the pilot burner bracket and the main burner.
 b. Check the ground lead from the GND terminal on the ignition module to the pilot burner.
 c. Check the ceramic flame rod insulator for signs of cracked or exposure to extreme heat. This can cause a short to ground and will prevent the pilot electrode assembly from sparking. Clean the flame rod with emery cloth if dirty.
3. Check spark ignition circuit. You will need a short jumper wire made from ignition cable or other heavily insulated wire.
 a. Close the gas valve manually.
 b. Disconnect ignition cable at the SPARK terminal of the control module. Move the ignition cable out of way.
 c. Energize the module by turning heater on or adjusting the thermostat to demand heat.
 d. Immediately place one end of the jumper firmly on the 24V (GND) terminal on the control module. Move the free end of the jumper slowly toward the SPARK terminal of the control module until a spark is established.
 e. Pull the jumper slowly away from the SPARK terminal and note the length of the spark gap. If the arc is 1/8 inch or more, then the voltage output is okay. If the spark is less than 1/8 inch or there is no spark, then replace the control module.
 f. Remove the jumper, turn heater off, reinstall the ignition cable and turn heater back on.

Buy:
Thermocouples at Amazon
Thermocouple adapters

Thermocouple Test and replacement
How to test water heater thermocouple
How to replace thermocouple pdf
How to replace thermocouple/ forum
Test thermocouple
Test thermocouple and thermopile




Thermocouple/ thermopile

Gas water heater burner assembly
How to Remove burner & replace thermocouple thermopile

How to light gas water heater
Pilot light goes out
Burner goes out when control knob turned to ON
Pilot light will not stay lit/ pdf
Pilot outage/ pdf
Attic Ventilation and Pilot Outage
Pilot outage and negative pressure
Pilot light maintenance/ pdf
Ventilating tight-house/ pdf
Pilot light troubleshoot
when thermostat set lower
Pilot problem or ECO or gas control?
Wind blows out pilot light
Pilot light or thermocouple?
Negative pressure blows out pilot

14 things needed for gas water heater & .pdf resources
What you need for operation of gas water heater.
General troubleshoot
1) Basic parts and operation
2) Adequate incoming air supply ... issues: closed doors, tightly insulated house, very hot attic.
3) Adequate air supply getting to burner... issues: dirty vent screen, dirty environment, maintenance.
4) Thermal cutoff  ... TCO ... issues: failed part, maintenance, vent.

5) Flammable vapor lockout .... issues: exposure to vapors, bad FV sensor, failed FV system,
6) Fuel supply to gas valve thermostat ... natural gas and propane are different ... issues: wrong gas, low pressure, moisture in pipe, undersized gas meter, supply line too small for BTU rating.
7) Gas valve thermostat regulates fuel supply ... issues: not enough gas, failed thermostat, failed gas control valve.

8) Fuel supply from thermostat to burner ... issues: maintenance, thermocouple-thermopile, gas control valve.
9) Clean and replace burner ... issue: periodic maintenance requires burner inspection, cleaning, and possible replacement

10) Functioning thermopile-thermocouple-pilot light ... issues: misalignment, failure of part.
11) Ignition of fuel supply by pilot light or hot surface igniter ... issues: pilot light, piezo igniter, electrode.

12) Power vent water heater troubleshoot ... issues: pressure switch, blower, blower sequence from gas control, outlet polarity
13) Venting combustion byproduct .... issues: vent in disrepair, other vents in house drawing air

14) Misc troubleshoot manuals

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