You’re standing in the shower, expecting a blast of hot water. Instead, you’re met with an icy shock. The first suspect? Often, it’s the pilot light on your gas water heater. That tiny blue flame is the heart of your hot water supply. But its behavior can be confusing. Does it always stay on, or is it supposed to go out sometimes?
For traditional gas water heaters with a standing pilot, the answer is yes. The pilot light is designed to burn continuously. It’s a small, always-on flame that ignites the main burner whenever the thermostat calls for heat. If it goes out, you lose your hot water. Modern units with electronic ignition are different; they only spark the pilot or burner when needed. Understanding this distinction is key to diagnosing problems. For homeowners tackling a stubborn pilot, having a reliable, long-reach lighter is a smart move. Many professionals recommend the Resideo CQ100A1013U 24-Inch for safe and easy relighting.
How a Water Heater Pilot Light Works
Think of the pilot light as a perpetual match. Its primary job is to be ready, instantly igniting the main gas burner. This happens when the water in the tank cools below the thermostat’s set point. The system is elegantly simple but relies on precise components.
The core of this safety and operation is the thermocouple. This copper sensor sits directly in the pilot flame. When heated, it generates a small millivolt current. This current signals the gas valve that the pilot is lit and it’s safe to allow gas flow to the main burner. No heat from the pilot means no current, and the gas valve shuts off the gas supply entirely. It’s a critical fail-safe.
Other key parts include the gas supply line, the pilot tube where the gas is emitted, and often a draft diverter or hood above the burner assembly. The draft diverter’s role is to ensure proper venting of exhaust gases and prevent downdrafts from blowing out the pilot flame. The entire ignition system in a standing pilot model is purely mechanical and thermal.
Normal vs. Problematic Pilot Light Behavior
So, should the pilot light on a water heater always be on? For a standard gas model, the expectation is a steady, blue flame. It should be quiet and consistent. You might notice it flicker slightly if a door slams, but it should recover immediately.
Problematic behavior is easy to spot. A pilot light that is yellow, lazy, or lifting off the thermocouple is a sign of trouble. The most common issue homeowners face is a pilot light that won’t stay lit. You might successfully relight it, only to find it extinguished an hour later. This is a clear signal that something is wrong. It is not normal for a water heater pilot light to go out on its own. When it happens, it’s your system asking for help.
How to tell if water heater pilot light is on is straightforward. Look through the viewport on the unit’s access panel. You should see a small, bright blue flame. If you see nothing, or just the glow of a hot thermocouple, the pilot is out. Always wait several minutes for gas to dissipate before attempting to relight.
Common Reasons a Pilot Light Won’t Stay Lit
Why does my water heater pilot light go out repeatedly? The causes range from simple fixes to serious safety concerns. Here are the most frequent culprits.
A Faulty Thermocouple
This is the number one reason for pilot light keeps going out issues. The thermocouple can fail due to age, corrosion, or simply being out of position. If it’s not fully immersed in the flame, it won’t get hot enough to generate the necessary current. The gas valve then shuts off the gas, snuffing the pilot. Sometimes, cleaning the tip with fine sandpaper can help, but often replacement is needed.
Issues with the Gas Valve
The gas valve is the brain of the operation. If its internal solenoid or thermopile (on some models) is failing, it may not register the thermocouple’s signal correctly. This can cause intermittent operation. Valve problems are less common than thermocouple issues but are a possibility in older units.
A Dirty or Clogged Pilot Orifice
The tiny hole where the pilot gas comes out can get clogged with dust, lint, or rust from the gas line. This restricts flow, resulting in a weak flame that can’t properly heat the thermocouple or is easily blown out. Careful cleaning with a needle or compressed air can resolve this.
Strong Drafts or Venting Problems
Your water heater needs proper airflow. A strong downdraft coming down the flue, often caused by wind or negative air pressure in the home, can blow the pilot out. Check that the draft diverter is clear and installed correctly. Also, ensure the room has adequate combustion air.
Low Gas Pressure or a Faulty Regulator
If the gas pressure from your supply line is too low, the pilot flame will be weak and unstable. This could be an issue with the home’s gas regulator or a problem further up the line with the utility company. This requires a professional diagnosis.
- Thermocouple failure (most common)
- Dirty pilot assembly
- Faulty gas valve
- Venting/draft issues
- Low gas supply pressure
Step-by-Step Guide to Relighting the Pilot
Before you start any water heater pilot light troubleshooting, find the instruction label on your unit. It has the manufacturer’s specific steps. Safety first: if you smell gas at any point, stop immediately. Leave the area and call your gas company. Here is a general guide for relight pilot light procedures on a standard gas water heater pilot system.
- Turn the Gas Control Knob to “Pilot”: Locate the gas control valve/thermostat. Turn the knob from “ON” to “PILOT.”
- Depress the Knob: Push the knob down fully. This starts the flow of gas to the pilot assembly.
- Ignite the Pilot: While holding the knob down, use a long lighter or match to ignite the pilot at the end of the tube. Hold the flame there.
- Hold for 60 Seconds: Keep the control knob depressed for about one minute after the pilot is lit. This allows the thermocouple to heat up.
- Release and Turn to “On”: Slowly release the knob. The pilot should stay lit. If it goes out, repeat steps 2-4, holding longer. Once stable, turn the knob to “ON.”
- Set the Temperature: Adjust the thermostat to your desired setting (typically around 120F). You should hear the main burner ignite.
If the pilot refuses to stay lit after several attempts, you’re likely dealing with one of the issues listed above. This is the core of how to check pilot light healthits ability to remain on consistently.
When to Call a Professional for Pilot Light Issues
Some pilot light safety and repair tasks are strictly for licensed technicians. Knowing when to call is as important as knowing how to relight.
Call a professional if:
- You smell gas strongly at any time, not just when relighting.
- The pilot light flame is consistently yellow or orange (indicating incomplete combustion).
- You see soot or scorch marks around the burner assembly.
- The pilot relights but the main burner does not come on.
- You’ve replaced the thermocouple and the problem persists, pointing to a potential gas valve issue.
- You are uncomfortable performing any of the steps.
Persistent pilot problems can be a symptom of a larger system issue. Investing in a good quality water heater from a reputable brand often means more reliable components from the start. Similarly, modern Navien tankless units eliminate the standing pilot entirely, using electronic ignition for efficiency and reliability.
Maintenance for a Healthy Pilot Light
Annual maintenance can prevent most pilot light headaches. A simple inspection and cleaning can keep everything running smoothly. Refer to this official energy guide for broader efficiency tips as well.
| Task | Frequency | Purpose |
|---|---|---|
| Visual Pilot Inspection | Monthly | Check for steady blue flame. |
| Dust/Vacuum Around Base | Every 6 Months | Prevents clogging of the pilot orifice. |
| Check Venting & Draft Diverter | Annually | Ensures no blockages or downdrafts. |
| Professional Flush & Inspection | Annually | Comprehensive safety and efficiency check. |
That tiny blue flame is a big deal. For traditional water heaters, it should be a constant, reliable presence. When it isn’t, listen. The fixes are often simplea thermocouple, a cleaning. But the message is critical. It’s your system’s way of ensuring safe, efficient operation. Regular checks take just a moment. They save you from cold showers and give you peace of mind. If the problem stretches beyond a simple relight, don’t hesitate. A professional can ensure your hot waterand your homestays safe.
