How to Relight an A.O. Smith Water Heater Pilot Light

Understanding Your Water Heater’s Pilot Light System

The pilot light in your A.O. Smith water heater serves as a critical ignition source for the main burner that heats your water. This small flame remains lit continuously in standing pilot light systems, ready to ignite the primary burner whenever hot water demand is detected. When the pilot light extinguishes unexpectedly, your water heating system ceases to function, leaving you without hot water until the pilot is reignited. Understanding how this system works and why the pilot light occasionally goes out is essential for maintaining your home’s comfort and preventing potential safety hazards.

Modern A.O. Smith water heaters incorporate sophisticated safety mechanisms designed to prevent dangerous gas accumulation. The thermocouple, a heat-sensitive safety device, monitors whether the pilot flame is burning. When the pilot light is active, the thermocouple becomes energized and keeps the main gas valve open. Conversely, if the pilot light extinguishes, the thermocouple cools rapidly and closes the gas valve, preventing uncontrolled gas flow into your home. This automatic safety feature means that a pilot light outage, while inconvenient, is not inherently dangerous due to these built-in protections.

Essential Safety Precautions Before Beginning

Before attempting any work on your water heater’s pilot light system, establishing a safe working environment is paramount. Safety should always be your primary concern when dealing with gas appliances, as improper procedures could create hazardous conditions.

Gas Odor Detection and Assessment

Your first step should always be checking for the presence of natural gas odors around your water heater. If you detect even a faint rotten egg smell—the characteristic scent added to natural gas for safety purposes—stop immediately and do not proceed. Instead, evacuate the area, leave your home, and call your gas utility company or a licensed professional from outside the building. A gas smell indicates a potential leak that requires professional diagnosis and repair before any pilot light work can safely commence.

Turning Off the Gas Supply

Locate the gas control knob on your A.O. Smith water heater, typically positioned near the base of the unit. Turn this knob firmly to the “OFF” position. This action immediately halts all gas flow to both the pilot burner and the main heating burner. Never skip this step, as it forms the foundation of your safety protocol by eliminating gas flow before you work near ignition sources.

Allowing Adequate Gas Dissipation Time

After turning off the gas supply, wait a minimum of ten minutes before proceeding with any relighting attempt. This waiting period is not arbitrary—it serves the critical purpose of allowing any residual gas that may have accumulated in the combustion chamber, burner tubes, and gas lines to safely disperse into the atmosphere. Attempting to relight the pilot before this gas has cleared could result in a sudden burst of flame or minor explosion if the accumulated gas ignites. This ten-minute waiting period is one of the most important safety measures you can implement.

Locating Components and Understanding Controls

Familiarizing yourself with your water heater’s physical layout and control mechanisms before you need to use them significantly increases your confidence and safety. Take time to identify all relevant components while your water heater is functioning normally.

Finding the Gas Control Valve

The gas control valve is typically a cylindrical or box-shaped component located at the base of your A.O. Smith water heater. On this valve, you will find several settings: “OFF,” “PILOT,” and “ON.” The valve may also include a red or orange button labeled as the ignition button or spark ignitor. Some models feature a small window or sight glass through which you can observe the pilot light’s flame. Take a moment to examine your specific model and identify these features so you know exactly what you’re working with when the pilot light goes out.

Understanding Valve Positions and Gas Flow

The orientation of the gas valve handle provides important information about gas flow direction. When the valve handle is perpendicular (at a right angle) to the gas supply pipe, the valve is in the “OFF” position and no gas flows through it. Conversely, when the valve handle is parallel (aligned with) the gas supply pipe, gas flows freely. Understanding this mechanical principle helps you verify whether you’ve successfully turned off the gas and gives you confidence in the valve’s operation.

Step-by-Step Pilot Light Relighting Procedure

Once you’ve confirmed that ten minutes have passed since turning off the gas and you’ve verified no gas odors are present, you can proceed with relighting your pilot light. Follow these steps methodically and avoid rushing through any stage of the process.

Positioning the Gas Control Valve Correctly

After waiting the required ten minutes, turn the gas control knob to the “PILOT” position. This setting restricts gas flow exclusively to the pilot burner, preventing gas from flowing to the main burner. This is an important safety measure because it ensures that if you accidentally create a larger flame during relighting, it will be limited in size and scope.

Initiating Ignition

With the valve set to “PILOT,” locate and press the ignition button, typically a red or orange button near the control knob. While holding this button down, use either a long-reach fireplace lighter, long matches, or a piezo igniter (sparking device) to ignite the gas at the pilot light opening. Modern A.O. Smith models often feature piezo igniters that create a spark without requiring an open flame—these are preferable because they eliminate the need for matches or external flames. If you’re using a lighter or matches, hold the flame near the pilot opening until you see the small blue flame ignite.

Maintaining Ignition Button Pressure

Continue holding down the ignition button for approximately thirty to sixty seconds after the pilot light ignites. This sustained pressure allows the thermocouple to heat up and become fully energized. The thermocouple must reach operating temperature for it to properly signal the gas valve to remain open. If you release the button too quickly, the valve may close prematurely and extinguish the newly lit pilot flame.

Returning to Normal Operation

After maintaining pressure on the ignition button for the required time, carefully release it. Observe the pilot light through the sight glass or opening to confirm it remains burning with a steady blue flame. If the flame persists, slowly turn the gas control knob from “PILOT” to “ON” to restore normal operation. This allows gas to flow to both the pilot and the main burner. Your water heater should now resume normal heating operation.

Troubleshooting When the Pilot Won’t Stay Lit

If you’ve followed the relighting procedure correctly but the pilot light repeatedly extinguishes after you release the ignition button, an underlying problem likely exists beyond simple pilot outage. Several components could be responsible for this frustrating situation.

Thermocouple Malfunction

The thermocouple may have degraded or failed, preventing it from properly sensing the pilot flame’s heat. A faulty thermocouple cannot generate sufficient electrical signal to keep the gas valve open, causing the valve to close and extinguish the pilot moments after ignition. If you’ve relighted the pilot successfully multiple times but it continues to go out immediately, thermocouple replacement by a professional technician is typically necessary.

Pilot Tube Obstruction

Dust, debris, or mineral deposits can accumulate inside the small tube that delivers gas to the pilot burner. This blockage restricts gas flow, making ignition difficult or impossible. If you notice weak flame or difficulty lighting the pilot, professional cleaning of the pilot tube may be needed.

Draft Problems and Airflow Issues

Your water heater requires proper ventilation and air intake for safe operation. If the venting system is blocked, damaged, or improperly configured, airflow interference can cause the pilot flame to blow out. Modern A.O. Smith heaters include fail-safe systems that prevent pilot ignition if certain airflow conditions aren’t met, as a protective measure against combustion problems.

Water Heater Age and Component Wear

Water heaters typically have operational lifespans of eight to fifteen years. If your A.O. Smith unit is approaching or exceeding this age range and you’re experiencing frequent pilot outages, multiple internal components may be approaching failure simultaneously. Professional inspection can determine whether repairs are feasible or whether replacement is more economical.

When Professional Service Becomes Necessary

Certain situations require professional intervention rather than DIY attempts. Knowing these limits is crucial for both your safety and your wallet.

Persistent Pilot Lighting Failures

If you’ve successfully relighted the pilot multiple times within a short period but it continues to go out, a professional technician should diagnose the underlying cause. Repeated failures indicate a component issue that requires specialized tools and expertise to resolve.

Gas Odors and Leaks

Any time you detect gas odors during or after your relighting attempt, cease work immediately and call a professional. Do not ignore these warning signs, as gas leaks pose serious safety risks including fire and explosion hazards.

Unusual Sounds or Behaviors

If your water heater produces unusual sounds like rumbling, popping, or hissing, or if you observe discoloration, rust, or water leaking around the base, professional evaluation is warranted. These symptoms may indicate problems beyond pilot light issues that require comprehensive assessment.

Preventive Maintenance for Long-Term Reliability

While some pilot light outages are inevitable, regular maintenance practices can minimize frequency and prevent premature component failure.

Regular Visual Inspections

Periodically examine your water heater for signs of rust, corrosion, mineral buildup, or water leaks. Early detection of these issues allows for timely intervention before they affect pilot light operation or overall performance. Schedule inspections at least annually or whenever you notice changes in water temperature or heating speed.

Monitoring Pilot Light Appearance

A healthy pilot light should display a steady, blue flame. If you notice yellow or orange coloring, flickering, or weak flames, these visual changes may indicate combustion problems or obstructions. Document when these changes occur and report them to a technician if they persist.

Professional Maintenance Service

Consider scheduling professional maintenance every two to three years. Technicians can clean internal components, inspect the thermocouple, verify proper gas pressure, and ensure all safety systems function correctly. This proactive approach often prevents emergency situations and extends your water heater’s operational life.

Frequently Asked Questions

Q: How do I know if my pilot light is completely out?

A: If you look through the sight glass and see no flame, or if you have no hot water despite allowing sufficient heating time, your pilot light is likely extinguished. Some units have indicator lights that show pilot light status.

Q: Is it safe to relight the pilot light myself?

A: Yes, relighting a pilot light is safe when you follow proper procedures, including turning off gas, waiting ten minutes, checking for gas odors, and following your manufacturer’s instructions. However, stop immediately if you detect gas smells or encounter repeated failures.

Q: What should I do if I smell gas during relighting?

A: Stop immediately, leave your home, and call your gas utility company from outside the building. Do not use your phone indoors, do not flip light switches, and do not create any potential ignition sources.

Q: How long should I hold the ignition button?

A: Hold the ignition button for thirty to sixty seconds after the pilot flame ignites. This time allows the thermocouple to heat up and signal the gas valve to remain open.

Q: Why does the pilot light keep going out?

A: Repeated pilot outages typically indicate thermocouple failure, pilot tube obstruction, airflow problems, or component wear. Professional diagnosis is recommended for persistent issues.

Q: Do I need special tools to relight the pilot light?

A: No special tools are required. You’ll need a long-reach lighter, long matches, or a piezo igniter. A flashlight is helpful if your water heater’s location is poorly lit.

Q: What is the thermocouple and why is it important?

A: The thermocouple is a safety device that detects pilot light heat. When the pilot is burning, it keeps the gas valve open. If the pilot goes out, the thermocouple cools and closes the valve, preventing gas from entering your home.