The pilot light on a water heater does not always stay on; it typically remains lit when the heater is in use, but it can go out due to drafts, a malfunctioning thermocouple, or if the unit is turned off for maintenance or repairs.
A water heater pilot light is a small flame that ignites the gas burner to heat your water. While most traditional gas water heaters keep the pilot light constantly lit, some modern models relight automatically when needed. Understanding how your pilot light works can help you troubleshoot issues and maintain your system efficiently.
How a Water Heater Pilot Light Works
The pilot light is a critical component in gas water heaters. When functioning properly, it should remain lit continuously to ensure hot water is always available. Here’s how it works:
- The pilot light heats a thermocouple or thermopile
- This generates a small electric current
- The current keeps the gas valve open
- When the thermostat calls for heat, gas flows to the main burner
- The pilot light ignites the main burner
Traditional vs. Modern Pilot Lights
Traditional water heaters maintain a constant pilot light, while newer models often use intermittent ignition systems:
| Type | Operation | Energy Use |
|---|---|---|
| Standing Pilot | Always stays lit | Higher |
| Intermittent Ignition | Lights only when needed | Lower |
Why Pilot Lights Go Out
Several factors can cause a pilot light to extinguish unexpectedly:
1. Thermocouple Issues
The thermocouple is a safety device that shuts off gas if the pilot light fails. Problems include:
- Dirt or corrosion buildup
- Improper positioning away from flame
- Complete failure requiring replacement
2. Gas Supply Problems
Insufficient gas flow can starve the pilot light:
- Partially closed gas valve
- Low gas pressure
- Condensation in gas line
3. Ventilation Issues
Proper airflow is essential for combustion:
- Blocked vents or flues
- Drafts blowing out the flame
- Insufficient combustion air
Troubleshooting a Pilot Light That Won’t Stay Lit
Before calling a professional, try these steps:
- Turn off gas supply and wait 5 minutes
- Clean around the pilot assembly
- Check thermocouple alignment
- Ensure gas valve is fully open
- Relight following manufacturer instructions
For more complex issues like gas valve problems, professional help may be needed.
Modern Alternatives to Standing Pilot Lights
Newer technologies eliminate constant pilot lights:
Electronic Ignition Systems
These systems only ignite when needed, saving energy. They include:
- Hot surface igniters
- Intermittent pilot systems
- Direct spark ignition
Tankless Water Heaters
Propane tankless water heaters heat water on demand without a pilot light, offering greater efficiency.
Safety Considerations
Gas appliances require proper care:
- Install carbon monoxide detectors
- Ensure proper ventilation
- Schedule annual maintenance
- Know how to shut off gas supply
According to U.S. Department of Energy, water heating accounts for about 18% of home energy use, making efficiency improvements valuable.
When to Call a Professional
Seek professional help for:
- Gas leaks (smell of rotten eggs)
- Repeated pilot light failures
- Unusual flame colors (should be blue)
- Water heater over 10 years old
For related heating solutions, consider ventless natural gas wall heaters as supplemental heat sources.
