You won't have a pilot light if you have a relatively new furnace. However, many older furnaces remain in service, and manufacturers continue to produce pilot light assemblies to keep these furnaces operational. The most recent models to still use pilot lights (and the ones likeliest to be still in service) feature much more modern designs than the pilot lights you may be imagining.
If your furnace has a relatively modern pilot light, you probably won't have to worry about lighting it manually with a flame. Still, these assemblies can fail, costing you money or stopping your furnace from running altogether. Recognizing the signs of a pilot light issue can help you understand when to call in a technician for further diagnosis and repair.
How Do Modern Pilot Lights Work?
Most modern pilot light assemblies use electronic ignition to save you the trouble of lighting the pilot by hand. Older assemblies may require a torch or a long match to light the flame. If you're unsure how your assembly works, there are usually clear lighting instructions on the pilot light enclosure. In most cases, relighting a pilot light is very straightforward.
Once lit, a pilot light should generally remain lit indefinitely. Pilot lights work by burning continuously, providing a constant ignition source when your thermostat calls for heat. Modern furnaces use alternative forms of ignition because running a pilot light 24/7 wastes gas and ultimately reduces the efficiency of your furnace.
Additionally, any modern pilot light will include a thermocouple to sense the presence of an active flame. This crucial safety device connects to a solenoid that holds the gas valve open as long as the flame remains lit. When the flame goes out, the solenoid closes and stops the gas supply to prevent an unlit pilot from causing a gas leak.
How Do You Know If Your Pilot Light Is Faulty?
Even modern pilot lights are relatively straightforward. If your pilot light will not light or goes out immediately, there's a high likelihood the problem is somewhere in the pilot light assembly. In most cases, there are only three potential failure points:
- The solenoid
- The tube supplying gas to the pilot light
- The thermocouple
Cleaning the thermocouple may help, but very old ones may require replacement. Likewise, it's often easier and faster to replace clogged supply tubes. Since it's possible to replace individual parts of the assembly, it's best to leave the diagnosis to a professional. An HVAC technician can identify the exact source of the problem so you won't have to replace the entire assembly.
If none of the common issues seem to be causing your pilot light to stay out, another possibility is an issue with the gas supply feeding the pilot light. Use furnace repair professionals to deal with any gas-related problems. Dealing with natural gas can be dangerous and often requires special licensing, so fixing your gas supply is not a do-it-yourself task.