How to Light a Gas Water Heater

Are you about to install a new gas water heater but unsure how to light it?

Many find the process daunting, especially if they’re accustomed to electric water heaters. However, lighting a gas water heater is a straightforward task that doesn’t require professional expertise.

Follow these steps and instructions to successfully light your gas water heater without hassle.

how to light a gas water heater

Before Lighting the Pilot of a Gas Water Heater:

Inspect Gas Lines for Leaks: Before proceeding, ensure the safety of your gas water heater by checking for potential leaks in the gas lines. This step is crucial for preventing hazardous situations.

Use a Soapy Water Solution: Avoid using a match or open flame to detect gas leaks. Instead, create a solution of soapy water.

Apply Soapy Solution: Brush the soapy water solution onto all gas pipes, joints, and fittings associated with the water heater.

Check for Bubbling Soap: Carefully observe for any bubbling of the soapy solution. The presence of bubbles indicates a gas leak. In such cases, immediately turn off the gas supply and proceed with necessary repairs.

Recheck for Leaks: After addressing any leaks and making repairs, recheck the gas lines to ensure there are no remaining leaks.

Rinse and Dry: Once the inspection is complete, rinse off the soapy solution thoroughly from the gas lines and fittings. Ensure all surfaces are wiped dry for safety and proper functioning of the gas water heater.

How to Light a Gas Water Heater Step-by-Step

Step 1: Remove the Outer Door

Begin by removing the outer door of the gas water heater to access the internal components safely.

Step 2: Set the Thermostat Dial

Adjust the thermostat dial to the “PILOT LIGHTING” position to prepare for lighting the pilot.

Step 3: Turn the Gas Control Knob Off

Turn the gas control knob clockwise to the “OFF” position. Ensure the knob is depressed slightly to allow the transition from “PILOT” to “OFF” without forcing it.

Step 4: Wait and Check for Gas

Wait for approximately five minutes to allow any residual gas to dissipate. If you detect the scent of gas during this time, follow the safety instructions provided earlier. If no gas odor is present, proceed to the next step.

Step 5: Open the Interior Door

Remove or open the interior door located beneath the gas control unit to access the pilot assembly.

Step 6: Locate the Pilot

Identify the pilot-follow metallic tube connected to the gas control unit, with the pilot positioned at the front of the burner.

Step 7: Turn the Gas Control Knob

If no gas odor is detected, turn the gas control knob counterclockwise to the “PILOT” position.

Step 8: Ignite the Pilot

Depress and hold in the control knob fully while immediately lighting the pilot with a match. Continue holding the control knob for about one minute after the pilot is lit to ensure it remains ignited. If the pilot goes out, repeat steps 3 through 8.

  • Note: If the knob doesn’t pop up when released, or if the pilot fails to stay lit after multiple attempts, seek professional assistance from a service technician or gas supplier.

Step 9: Replace the Interior Door

Once the pilot is lit and stable, replace or close the interior door securely.

Step 10: Turn the Gas Control Knob On

At arm’s length, turn the gas control knob counterclockwise to the full “ON” position. Avoid using the gas control knob to regulate gas flow.

Step 11: Adjust the Thermostat

From a safe distance, set the thermostat to the desired temperature setting, typically indicated by a mark (▲) around 120°F. Be aware of local regulations regarding water temperature requirements. Refer to the instruction manual for adjustments and cautions regarding higher temperature settings.

Step 12: Replace the Outer Door

Finally, if not done previously, replace the outer door securely to cover the gas control on/off knob and temperature adjustment knob, ensuring the gas water heater is properly enclosed.


• Do not attempt to light any equipment.

• Do not contact any electrical swap; don’t use any phone in your construction.

• Immediately name your gas provider from a neighbor’s phone. Follow the gas supplier’s instructions.

• If you can’t attain your gas supplier, name the fireplace department.

3. Use only your hand to push in or flip the gas control knob. Never use instruments. If the knob is not going to push in or turn by hand, don’t attempt to restore it, call a certified service technician. Force or tried restore might lead to a fireplace or explosion.

4. Do not use this appliance if any half has been underwater. Immediately name a qualified service technician to examine the equipment and to switch any part of the control system and any gas control which has been underwater.

How to Turn Off a Gas Water Heater

1. Set the Thermostat Dial: Begin by setting the thermostat dial to the “PILOT LIGHTING” position to prepare for shutting off the gas water heater.

2. Turn Off the Gas Control Knob: Turn the gas control knob clockwise to the “OFF” position. Ensure the knob is depressed slightly to facilitate the transition from “PILOT” to “OFF” without applying force.

3. Replace the Outer Door: If you removed the outer door during the process, replace it securely to ensure the gas water heater is properly enclosed.

Important Safety Information:

Due to the nature of conventional gas water heaters, water temperature can vary significantly, up to 30°F higher or lower, at the point of use, such as bathtubs, showers, sinks, etc.

This means that even when the temperature adjustment dial is set to approximately 120°F, the actual water temperature at any hot water faucet could range from as high as 150°F to as low as 90°F.

It’s crucial to recognize that the primary purpose of any water heater is to heat water. While hot water is essential for various tasks such as cleaning and sanitizing, it also presents a scald hazard. The risk of scalding varies depending on factors such as time, individuals involved (e.g., adults, children, elderly), and their vulnerability.

The thermostat of your water heater is factory-set at its lowest position to mitigate the risk of scald injuries. However, it is adjustable and can be reset to the desired temperature setting.

The mark (▲) indicating approximately 120°F is typically the recommended starting point. However, some states may mandate a lower setting.

If you require hotter water, follow the instructions for temperature adjustment provided below, but be mindful of the warnings outlined in this section.

Temperature Adjustment Instructions:

To adjust the water temperature, turn the water temperature dial clockwise to decrease the temperature or counterclockwise to increase it. Take caution and adhere to the warnings provided in this section when making adjustments.

Pilot lighting – Set here before attempting to light pilot

  Temperature Setting    Time to Produce 2nd & 3rd Degree Burns on Adult Skin  
  VERY HOT= approx. 160°F    About 1/2 second  
  C= approx. 150°F    About 1-1/2 second
  B= approx. 140°F    Less than 5 seconds
  A= approx. 130°F    About 30 seconds
  ▲= approx. 120°F    More than  5 minutes
  LOW= approx. 80°F    ___________

If overheating happens or the gas provider fails to close off.

  1. turn “OFF” the handbook gas control valve to the equipment.

Why is my gas water heater not igniting?

If your gas water heater is not igniting, several potential reasons could be causing this issue. Here are some common factors to consider:

Pilot Light Issue: The pilot light may be out or malfunctioning. Check to see if the pilot light is lit. If it’s out, you may need to relight it following the manufacturer’s instructions. If the pilot light won’t stay lit, it could indicate a problem with the thermocouple or pilot assembly that needs attention.

Gas Supply Problems: Ensure that there is an adequate supply of gas to the water heater. Check other gas appliances in your home to see if they are working correctly. If no gas is reaching the water heater, there may be a problem with the gas valve, gas line, or gas supply to your property.

Thermocouple Issues: The thermocouple is a safety device that detects the presence of a pilot flame. If the thermocouple is faulty or dirty, it may not detect the pilot flame, causing the gas valve to remain closed. Cleaning or replacing the thermocouple can resolve this issue.

Gas Control Valve Problems: A malfunctioning gas control valve can prevent the flow of gas to the burner, preventing ignition. If the gas control valve is defective, it may need to be repaired or replaced by a qualified technician.

Air Supply Blockage: Insufficient air supply to the burner can prevent proper ignition. Check for any obstructions in the venting system or air intake vents leading to the water heater. Clearing any blockages can improve airflow and help with ignition.

Electronic Ignition Problems: If your gas water heater has an electronic ignition system, issues with the ignition module or wiring can prevent the burner from igniting. Testing and troubleshooting the electronic ignition components may be necessary to identify and resolve the problem.

Safety Features Engaged: Some gas water heaters are equipped with safety features that can shut off the gas supply if certain conditions are not met, such as inadequate ventilation or overheating. Check the manufacturer’s manual for information on resetting any safety features that may have been triggered.

If you are unable to diagnose or fix the problem with your gas water heater not igniting, it’s advisable to contact a qualified HVAC technician or plumber for professional assistance and repairs. Safety should always be the top priority when dealing with gas appliances.

Where is the pilot light on a gas water heater?

The pilot light on a gas water heater is typically located near the bottom of the unit, beneath the main burner assembly. It can be found behind the access panel or cover on the front of the water heater, positioned close to the gas control valve.

The pilot light serves as a continuous flame, essential for igniting the gas and heating the water inside the tank. When relighting or troubleshooting the pilot light, refer to the manufacturer’s instructions and exercise caution to ensure safety.

Do gas water heaters light themselves?

Yes, many modern gas water heaters are equipped with self-ignition systems, also known as electronic ignition or pilotless ignition systems. These systems automatically light the burner when hot water is needed, eliminating the need for a continuously burning pilot light.

There are two main types of self-ignition systems:

  1. Hot Surface Ignition (HSI): This type of system uses a hot surface igniter to ignite the gas burner when the water heater calls for heat. The igniter heats up when activated, igniting the gas and starting the heating process.
  2. Spark Ignition: In this system, a spark electrode generates a spark to ignite the gas when the water heater is turned on. The spark is produced when the control module sends an electrical signal to the electrode, creating a spark that lights the gas burner.

These self-ignition systems are efficient and convenient, as they only operate when hot water is needed, reducing energy consumption compared to traditional pilot light systems. However, it’s essential to follow proper maintenance and troubleshooting procedures if issues arise with the self-ignition system to ensure the continued operation of the gas water heater.

Frequently asked questions:

How to replace a thermocouple on a water heater?

Start by ensuring the gas supply and pilot light are turned off for safety. Disconnect the old thermocouple from the control valve and carefully install the new one, making sure it’s securely connected.

Afterward, relight the pilot light following the manufacturer’s instructions. For a more detailed walkthrough, including safety precautions and troubleshooting tips, refer to our comprehensive guide on Replacing a Thermocouple on a Water Heater.

How to test a water heater element?

Begin by turning off the power to the water heater and draining the tank partially to access the heating element. Disconnect the wires from the element and use a multimeter to measure the resistance across the terminals.

Compare the resistance reading to the manufacturer’s specifications to determine if the element is functioning properly. If the reading deviates significantly, it may be necessary to replace the element. For a thorough step-by-step guide, explore our detailed post on Testing a Water Heater Element.

How to vent a tankless water heater?

Proper venting is crucial for the safe and efficient operation of a tankless water heater. Follow the manufacturer’s guidelines to determine the appropriate venting requirements for your specific model.

Select the correct type and size of vent pipe according to local building codes and regulations.

Install the vent pipe securely, ensuring proper alignment and sealing to prevent leaks and maintain optimal airflow. For a more comprehensive understanding of the venting process, check out our detailed guide on Venting a Tankless Water Heater.

Why is the water heater leaking?

Water heater leaks can be caused by various factors, such as loose fittings, corroded pipes, or a faulty pressure relief valve. Begin by inspecting the water heater for visible signs of leakage and addressing any loose connections or damaged components.

If the leak persists, it may be necessary to replace the pressure relief valve or other components. For a deeper dive into the common causes of water heater leaks and how to troubleshoot them effectively, refer to our informative guide on Water Heater Leaks.

How to strap a water heater?

Strapping a water heater is essential for seismic safety and compliance with building codes. Begin by selecting sturdy metal straps and positioning them above the midpoint of the water heater.

Securely attach the straps to the wall studs and tighten them to prevent the water heater from tipping over during seismic events. For detailed instructions and best practices on strapping a water heater, consult our comprehensive guide on Strapping a Water Heater.

How to clean a tankless water heater?

Regular maintenance, including cleaning, is vital to uphold the efficiency and longevity of your tankless water heater. The process involves flushing out mineral deposits and debris that accumulate over time, hindering performance.

Dive deep into our extensive guide on Cleaning a Tankless Water Heater to discover effective descaling methods, maintenance schedules, and expert recommendations to keep your unit running smoothly.


In summary, lighting a gas water heater involves simple steps for safety and efficiency. By checking for gas leaks, following manufacturer guidelines, and understanding key components like the gas control knob and pilot light, users can safely ignite their water heaters.

Regular maintenance ensures continued reliability. Prioritize safety and seek professional assistance if needed for peace of mind and optimal performance.

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