Things You'll Need
Spray bottle with soapy water in it
Phillips head screwdriver
2 compression nuts
The more do-it-yourself homeowners accomplish themselves, the less money they spend getting others to do things for them. That said, check local building codes before attempting to work on your furnace yourself to see if this repair requires a professional. When working with gas, always err on the side of caution. Although the odor in natural gas is man-made, it is possible for it to dissipate before the gas is completely gone. Provide plenty of ventilation.
Locate the breaker that controls the flow of electricity to the furnace and switch it to the off position. Close the gas valve located next to the furnace. Remove or extinguish any open flames in the area of the furnace.
Open a window close by to be certain all the gas fumes escape the area you are working in. Remove the cover to the furnace's gas regulator with a screwdriver to expose the thermocouple and pilot tube. They both connect to the gas regulator.
Spray some soapy water on the connection of the furnace pilot tube and check for bubbles that indicate a leak. If leaks occur, wait until it stops before proceeding to allow the rest of the gas in the tube to escape.
Back out the nut where the pilot tube meets the regulator with a wrench. Follow the pilot tube to its other end and repeat the process there as well. Pull the pilot tube free.
Measure the length of the tube and cut another piece with the tube cutter. Bend the tube using the old one as a guide so it will fit correctly. Do not make any sharp bends to prevent kinks in the line that could cut the gas flow to the burner.
Push the compression nuts on the ends of the tubing. Check the ends of the tubing for burrs and make sure they are square. Tubes that are not square on the ends won't seat properly inside the gas regulator or the burner.
Insert one end of the tube into the gas regulator until you feel it stop. Hold the tube in place and tighten the compression nut with your other hand until it stays. Tighten it with a wrench one more turn. Repeat this at the other end of the pilot tube.
Turn the gas on. Hold the pilot light button on the regulator down and spray the new connections with the soapy water to check for leaks. Adjust if necessary. Light the pilot light according to the instructions on your furnace. Turn the breaker back on.
If gas leaks occur where the pilot tube meets the regulator, replace the tubing. Once the compression seal is compromised, it cannot be resealed by tightening the compression nut.
Never work on gas lines with gas in them.