Every natural gas furnace contains a pilot light which is there to ignite the gas burner. This component of the furnace must be on for the unit itself to be running. Troubleshooting problems with your pilot light is not necessarily difficult. Simply follow the guide below for helpful tips.
Understand Your Pilot Light
Before you can troubleshoot anything, you have to know what is going on in the first place. There is a component of the natural gas furnace called the thermocouple, and it acts as a sensor for the pilot light to determine if the heat coming from the burner is enough to handle the burning fuel from the burner. If the pilot is not producing enough heat, then it shuts off the gas valve. This is all necessary to prevent gas from leaking into your home and causing fires beyond where they need to be. In short, if the pilot light goes off, the furnace ceases production.
Prepare to Relight the Pilot Light
Assuming that the pilot light is out, you have to relight it. There are slight variations on how to do this from one furnace or another. To be on the safe side, check your instruction manual or the instructions listed on the furnace door for specifics about your unit. For the purposes of this guide, we will assume that you have a standing pilot light (one that remains lit at all times)
Relight the Pilot Light
Once you have reviewed the instructions for your unit, you will need to turn your thermostat to "Heat" and crank it up to 80 degrees to get it going. Find the pilot valve on your furnace and find the box the knob with the on/off options. Turn that knob to "Off". Find the pilot light near the gas burner tubes. Use a long match or lighter to ignite the flame. Do so by setting the knob or reset button from "Off" to "Pilot" Hold the lit match or lighter up to the pilot and depress the knob or button for 30 seconds. On th pilot remains lit, turn the knob or button to "On".
If the Relight Does Not Work
First try to wait a few minutes and then repeat the procedure above. Use a time of 60 seconds instead to ensure that the thermocouple has enough time to get hot. If that doesn't solve the problem, proceed onto other troubleshooting techniques.
If the Pilot Does Not Stay Lit
If you find that the pilot light does not remain lit after re-ignition, you likely have a problem with your thermocouple. Consult with your instruction manual once again to find out how to replace that unit. Then relight and test accordingly.
If the Flame is Irregular
If you have a faint or irregular flame coming out of your natural gas furnace, you may need to be adjusted. The flame should be blue, not yellow. If it is not the right color, then it means it's not the right temperature and could be sending bad signals to the thermocouple. Find the screw for your pilot made to adjust the flame. Follow your instruction manual to determine how to set it.
If you notice your flame is flickering, you likely have a draft issue. If there is a spitting motion coming out, there may be dirt in the tubes. You can clean this out with a small nail.