Water Heater Rescue: Know-How, Troubleshooting, Anodes graphic

Lingo > Thermocouple

More Lingo:
A thermocouple paralleling the gas line from the control to the burner

Thermocouples are found on residential water heaters, primarily. They extend into the flame of a pilot light on one end, and screw into the temperature control on the other and allow it to make the water heater main burner fire when the thermostat senses that the water temperature has gone too low.

Look at the photo at right. The tube at the bottom is the thermocouple.