If the thermocouple is working you should be able to measure 30 to 40 millivolts of voltage at the connection end of the tube when the pilot flame is on.
Gas water heater thermocouple replacement.
If your pilot light won t stay lit the thermocouple probably needs to be replaced.
Step 8 reattach the manifold tube pilot tube and thermocouple to the gas control valve thermostat and tighten them using the adjustable wrench.
Once the pilot supply tube burner supply tube and thermocouple are disconnected from the gas control valve see above simply lift and remove the burner assembly from the bottom of the water heater.
Replace the two piece wire connector onto the thermocouple and igniter wire securing it with the retainer clip and slide the manifold burner assembly back into the water heater.
Honeywell home cq100a1005 u cq100a1005 replacement thermocouple for gas furnaces boilers and water heaters 36 inch 4 7 out of 5 stars 188 9 79 honeywell cq100a1021 u cq100a1021 replacement thermocouple for gas furnaces boilers and water heaters 18.
Make sure that the gas controller is in the off position before attempting this repair.
Then detach the thermocouple from the burner and take it with you to the home center or hardware store to ensure you buy the right replacement.
Unfasten the three nuts that hold the thermocouple and the two gas tubes to the valve.
Remove burner assembly.
Turn off the gas supply.
Then unfasten the three nuts that hold the thermocouple and the two gas tubes to the valve.
First shut off the gas valve on the water heater and the gas valve on the gas line near the heater.
Replacement thermocouples using universal mounting include clips and fittings that will work on most gas fired heaters and water heaters.
How to replace the thermocouple on a standing pilot water heater.
A new one costs about 5 to 10 and is easy to install.
The thermocouple has two ends.