Lighting a gas water heater is a common maintenance task for many homes, but it must be done with care. This guide covers essential safety steps, preparation, and a clear, step-by-step process to light both standing-pilot and modern hot-surface igniter models. It also includes troubleshooting tips and ongoing maintenance to keep your system running efficiently. Following these best practices helps prevent gas leaks, exposure to flames, and other hazards while ensuring a reliable hot water supply.

Safety First

Gas appliances pose risks, including gas leaks, fire hazards, and carbon monoxide exposure. Before attempting any lighting procedure, ensure the area is well-ventilated and free of flammable materials. If you smell gas—often described as a rotten egg odor—do not attempt to light the heater. Evacuate the area and call your gas company or emergency services immediately.

Turn off electricity to the water heater if you will be performing maintenance that could create a spark, and never strike a match or use an open flame near the appliance. Use the gas control knob and manual shut-off valve as described by the manufacturer. If you are unsure about the model or safety steps, consult a licensed technician.

What You’ll Need

Gather these essential items before you start:

Clean, dry workspace with good ventilation
Flashlight or headlamp for visibility
Protective gloves and eye protection
Owner’s manual for your specific water heater model
Soap and water to check for leaks
Rag or towels to absorb any spills

Note: Some modern gas water heaters use an electronic ignition instead of a standing pilot. Check if your model requires a different approach and follow the manufacturer’s instructions exactly.

Step-by-Step Lighting Process

The exact steps can vary by model. The following steps cover common procedures for standing-pilot systems and briefly address electronic ignition units. Always defer to your manual if there are discrepancies.

Turn off the gas supply to the heater for a full 5 minutes if you recently performed maintenance or suspect a leak. This allows any accumulated gas to dissipate.
Access the access panel and locate the pilot assembly. For standing-pilot models, you’ll typically find a gas control knob labeled OFF, PILOT, and ON.
Set the gas control knob to OFF and wait sixty seconds to clear any residual gas, then return it to PILOT or ON as instructed by the manual.
If your model has a standing pilot, depress and hold the reset/ignition button while you light the pilot with a long, safety-rated lighter or match held at the pilot area. If you smell gas or cannot ignite the pilot after multiple attempts, leave the area and call a professional.
Once the pilot flame is lit, continue to hold the control knob in the PILOT position for about 30-60 seconds to heat the thermocouple or safety sensor, then release and set the knob to ON. The main burner should stay lit when you turn on hot water.
For electronic ignition models, set the control knob to ON and follow the on-screen or manual prompts to initiate the electronic spark. If the burner does not ignite within several seconds, turn the control to OFF, wait a minute, and try again. If ignition fails repeatedly, shut off gas and call a professional.
Close the access panel and restore power if applicable. Turn on hot water at a nearby faucet to confirm the heater is producing hot water within a reasonable time frame.

Troubleshooting Common Issues

Several issues can prevent lighting or sustaining flame. Here are common problems and practical fixes:

No flame after ignition: Ensure the gas valve is fully open and the thermocouple or flame sensor is clean. If the pilot flame is weak or flickering, extinguish, wait, and re-light carefully. If the flame does not stay lit, there may be a thermocouple issue.
Gas smell persists: Evacuate and call the gas company. Do not attempt to light the heater again until professionals verify there are no leaks.
Pilot goes out frequently: Common causes include a faulty thermocouple, poor airflow, or a dirty pilot orifice. Cleaning or replacing components may be necessary.
Water not hot enough or fluctuating: This may indicate a faulty thermostat, improper temperature setting, or sediment buildup. Flush the tank or check thermostat settings as advised by the manufacturer.
Ignition system clicks repeatedly without flame: Could indicate ignition electrode or wiring issues. Do not tamper with electrical components; contact a professional.

Always consult the manual for diagnostic codes and model-specific guidance. If you’re unsure about any step, stop and seek professional assistance to prevent injuries or property damage.

Maintenance And Long-Term Care

Regular maintenance keeps a gas water heater safe and efficient. Key tasks include:

Inspect for gas leaks and corrosion around connections at least annually.
Check and tighten fittings, especially the gas line and vent system, to prevent leaks and ensure proper venting.
Test the operability of the safety devices: thermocouple, pilot flame, and the pressure relief valve.
Flushing the tank annually helps remove sediment, improving efficiency and hot water output.
Keep the area around the heater clear of clutter and flammable materials to maintain safe operation.

If your water heater is older than 10-15 years, consider scheduling professional maintenance or replacement, as efficiency and safety standards may have improved since installation.

When To Call A Professional

Some situations require expert attention. Contact a licensed plumber or gas technician if you notice any of the following:

Unpleasant gas odors that persist after venting and shut-off procedures
Repeated ignition failure or flame that won’t stay lit
Visible damage to the unit, venting system, or gas lines
Water leaks at the tank or connections, or abnormal noises during operation
Electrical concerns or unfamiliar error codes displayed by an electronic ignition system

Professional service reduces the risk of gas exposure and ensures the unit operates within safety standards and local codes.