The pilot light in your gas furnace ignites the gas supply to create heat. To work properly, the pilot's flame must be the proper size. If the pilot's flame is too short, it won't reach the thermocouple and ignite the gas. The flame will frequently burn out, necessitating constant relighting. If the flame is too high, it will create residue build-up on the thermocouple and the interior of your furnace, preventing the furnace from working properly. Adjusting the pilot light is a simple task that can be done in minutes. Be aware, most modern furnaces do not allow you to adjust the pilot, as they use automatic pilot lights rather than the older manual style.
Remove the access panel on your furnace. This is typically located near the bottom of your furnace. Slide the panel up and pull it out and away from the furnace.
Visually inspect the pilot light. The pilot light will be located along the bottom of your furnace. Inspect the pilot to determine if the flame is too long or too short. Next to the pilot light port is the thermocouple. The pilot light should cover the end of the thermocouple by 1/2 inch.
Adjust the pilot light screw to adjust the flame. The pilot light screw is located at the end of the pilot light supply tube, where the tube connects to the gas controls. Use a flat head screwdriver to adjust the screw. Turn the screw counter-clockwise to increase the size of the flame and clockwise to decrease the flame.
Replace the access panel by sliding it back into place.
The flame on your pilot light should be blue. If there is yellow in your flame you may have a bad gas line. Contact a repair service to have it fixed.