Adjusting the pilot light; replacing the thermocouple. Caution: Don’t relight the pilot or attempt to make any repairs if there’s a strong gas odor. Close the main shutoff valve, turn off power to the burner at the circuit-breaker panel or the fuse box, and call the gas company immediately.
In a gas burner, natural or bottled gas is mixed with air and ignited by a pilot light or spark ignition. A boiler or a furnace converts the heat to steam, hot water, or warm air. The thermocouple safety device cuts off gas flow if the pilot light goes out.
Twice a year turn off the gas and power to the burner and, with a crevice tool, vacuum the air shutters. Every 3 to 4 years the gas company should service the burner and clean the fuel passages and the vent. Periodically check the burner flames. If they are yellow, have the gas company adjust the air-gas mixture. Adjusting the pilot
The thermocouple cuts off the gas supply if the pilot light is too low to heat it. A pilot-adjustment screw on the control unit of some models regulates the pilot flame. Remove the screw cap, if any, and turn the screw counterclockwise to raise the flame, clockwise to lower it.
To reignite the pilot, set the house thermostat to the lowest temperature setting. Follow the instructions near the control unit.
Replacing the thermocouple
Do not try to relight the pilot more than twice. If it goes out again, replace the thermocouple or call the gas company. To replace the thermocouple, close the main shutoff valve and turn off power to the burner. When the thermocouple is cool, unscrew the lead from the combination control and wipe the threaded connection at the control with a clean, lint-free rag.
Unscrew the nut holding the thermocouple and the lead to the pilot light bracket. Fasten the new thermocouple and lead to the bracket; connect the other end of the lead to the combination control.