How to Ignite a Gas Water Heater: A Simple Guide

Are you looking to learn how to ignite a gas water heater?

Look no further!

In this detailed guide, we will provide you with step-by-step instructions on how to safely and effectively ignite a gas water heater. From understanding the necessary safety precautions to mastering the ignition process, we’ve got you covered.

Gas water heater
Gas water heater

Additionally, we’ll explore different types of ignition systems, outlining their pros and cons. Get ready to acquire the knowledge and skills you need to confidently ignite your gas water heater and enjoy a steady supply of hot water.

How to Ignite a Gas Water Heater: Things to Consider

Note: Do not attempt to light or relight a water heater if you detect the smell of gas. In such cases, it is crucial to evacuate the premises and promptly contact your gas supplier for immediate assistance. If you encounter any problems with your unit, it is highly recommended to seek the services of a professional plumber. Your safety and well-being are of utmost importance.

Introduction to Gas Water Heaters and Ignition Options

A gas water heater is an essential component found in many homes across North America, utilizing natural or propane gas to heat water. These units typically have a lifespan of over 10 years and come with warranties ranging from 6 to 12 years. However, throughout their usage, various issues may arise. Some problems are relatively simple to fix, making them suitable for DIY enthusiasts, while others require professional assistance due to their complexity.

Although gas water heaters share similarities with their electric counterparts, they are generally more intricate and demand a higher level of expertise for servicing and troubleshooting.

Each gas-powered unit is equipped with a gas control valve, which integrates a gas valve, a thermostat, and an ignition system.

The gas valve is responsible for releasing gas into the combustion chamber when the thermostat signals the need for water heating. Gas water heaters can have different types of ignition devices, allowing homeowners to manually or automatically ignite the burner.

Related: Gas water heater is not igniting – troubleshooting tips

How to Ignite a Gas Water Heater: Lighting Options and Instructions

There are several devices commonly used to light a gas water heater. These devices serve the purpose of igniting the gas burner to initiate the heating process. Here are a few examples:

  1. Standing pilot light: This traditional ignition method involves a continuously burning small flame known as the pilot light. It is manually lit and remains on to ignite the main gas burner when needed. It works together with the thermocouple, which must be in contact with the flame all the time.
  2. Electronic ignition: Electronic ignition systems use various methods to ignite the gas burner, such as hot surface ignition, spark ignition, or intermittent pilot ignition. These systems often utilize sensors, control boards, and electrical components to initiate the ignition process automatically.
  3. Piezo igniter: A piezo igniter generates an electric spark by pressing a button or trigger mechanism. This spark ignites the gas and initiates the burner flame. Piezo igniters are commonly found in portable or outdoor gas water heaters, and they do not require an electrical connection to operate.
  4. Direct ignition: Also known as a direct spark ignition, this type of ignition system uses an electric spark to directly ignite the main gas burner, eliminating the need for a pilot light.

Note: In some models, when a call for heating is initiated, the ignition system will make multiple attempts to light the burner. If the control panel fails to detect ignition, the water heater enters a lockout state and displays an error code.

Every gas device is equipped with a label containing instructions on how to ignite a water heater. It is crucial to refer to this label.

Additionally, ensure that there is an unobstructed gas flow from the supplier and that the main shut-off valve is open.

Before turning on the unit, make sure the tank is filled with water.

How to Light a Gas Burner if a Water Heater Is Equipped With a Hot Surface Igniter (HSI)

Gas water heaters can utilize hot surface igniters (HSI), which are resistance elements typically made of silicon carbide or silicon nitride. When a specific voltage is applied to the HSI, it begins to glow, ranging in color from orange to red. This glowing ignites the gas with the heat generated.

It is worth noting that the majority of gas water heaters are equipped with pilot lights and piezo igniters. However, advanced models often incorporate hot surface igniters for ignition. Some older models may lack igniter buttons, requiring the use of a long matchstick or a BBQ lighter for manual ignition.

To light a gas water heater using a hot surface igniter, follow these steps:

  1. Safety first: Prior to starting, ensure there are no signs of gas leakage. If you detect a gas odor, immediately leave the area and contact your gas supplier for assistance.
  2. Power On: Turn on the electrical power to the water heater.
  3. Temperature adjustment: Set the temperature on the gas control valve to your desired level. The exact method may vary based on the specific model.
  4. Ignition process: The hot surface igniter (HSI) will initiate the ignition sequence automatically. It will begin to glow, reaching the required temperature to ignite the gas.
  5. Monitor the glow: Observe the HSI and ensure that it is consistently glowing brightly. If the glow is weak or absent, it may indicate a malfunction requiring professional attention.
  6. Gas ignition: Once the HSI reaches the appropriate temperature, it will ignite the gas burner, initiating the heating process. The recommended temperature is within range of 120-125 F for optimal performance.
  7. Check the flame: Verify that the burner flame is present and burning steadily. A blue flame is typically indicative of proper combustion.
  8. Safety checks: Regularly inspect the hot surface igniter for any signs of damage or wear. If you notice any issues, it is advisable to contact a professional technician for inspection and repair.

Instructions on How to Ignite a Water Heater Using a Pilot Light and Piezo Ignition

  • Locate a gas control valve found at the bottom of the unit. This is a command center where you light a pilot, turn ON or OFF gas supply to a water heater, and where you would change the temperature.
  • Remove the metal cover plate to get access to a viewport and where you can visually check the status of a pilot and a burner flame.
  • If your heater was previously working, it is recommended to turn the gas OFF and let it sit for 5 minutes so any excess gas inside the gas chamber can disappear.
  • Turn the thermostat to its lowest position.
  • Turn the gas control knob to the “pilot” position.
  • Press the knob and hold it down. At the same time, press a separate ignition button to ignite the standing pilot. It will repeatedly click, generating a spark. The electric spark will light the pilot.
  • Once the pilot is ON, keep the knob pressed for 30 seconds and then release it slowly. It pops back up. Some models have a status light that blinks when the pilot is lit. The pilot should now burn steadily. If not, repeat the procedure but keep the gas control knob pressed longer. This will allow the pilot flame to heat the thermocouple. Once it detects the flame, the gas valve opens.
  • With the standing pilot burning, turn the gas knob to the ON position to light the main gas burner inside the water heater. You will hear a distinct “whooshing” and “whoomp” sound as the gas burner ignites.
  • Set the thermostat to the temperature you want it (the recommendation is around 120 F).
  • Put the cover plate back.

Note: The above instructions pertain to a gas water heater equipped with the Honeywell gas control valve. While the procedure may be similar for models with different types of gas control valves, it is essential to consult the specific manufacturer’s instructions for accurate guidance.

Instructions on How to Manually Ignite a Water Heater

  • Locate the gas control valve found at the bottom of your water heater.
  • Remove the metal cover and access (inner) plates. You will now have access to the gas combustion chamber with the pilot assembly and the gas burner.
  • If the unit was previously working, turn the gas OFF and wait for 5 minutes until there is no gas inside the unit.
  • Turn the thermostat to its lowest position.
  • Turn the gas control knob to the “pilot” position.
  • Push the ON/OFF knob down. Use a flashlight to find the pilot. While pressing the knob down, bring a BBQ lighter close to the standing pilot assembly and light the pilot. Keep pressing the gas control knob for 30-60 seconds, or until the thermocouple gets heated enough to keep the gas valve in the ON position.
  • The pilot should be lit now. If not, repeat the procedure but keep the gas control knob pressed longer. This will allow the pilot flame to heat the thermocouple so it can detect the flame.
  • With the standing pilot ON, turn the gas knob to the ON position to light the main gas burner inside the water heater.
  • Set the thermostat to the temperature you want it (the recommendation is around 120 F).
  • Put all the cover plates back.

Note: If you are unable to light the standing pilot on the first attempt, repeat the process carefully to avoid releasing excessive gas into the combustion chamber. In the case of power vented water heaters, the burner shuts off when the thermostat is satisfied, while the blower continues running in post-purge mode. The unit remains in standby mode until the next heating cycle.

Is It Safe to Relight a Pilot if It Goes Out?

It is generally safe to relight a pilot light if it goes out, but it is essential to follow proper safety procedures. Before attempting to relight the pilot, make sure to turn off the gas supply to the water heater and wait for a few minutes to allow any accumulated gas to dissipate. This step helps prevent the risk of gas buildup and potential hazards.

The procedure of relighting a pilot light is the same as explained in the text above.

However, if you encounter difficulties or the pilot light fails to stay lit despite repeated attempts, it’s recommended to seek professional assistance from a qualified technician. They possess the expertise to inspect the water heater, identify underlying issues, and ensure safe operation.

There can be various reasons why a pilot light goes out, including:

  • Not enough combustible air
  • Dirty thermocouple
  • Dirty pilot orifice
  • Damaged, dislocated, or a faulty thermocouple
  • Flame blown out (draft or downdraft, for example)


Knowing how to properly ignite a gas water heater is essential for ensuring its safe and efficient operation. Whether using a pilot light, piezo igniter, or hot surface igniter, following the correct steps and adhering to safety precautions is crucial.

If you find that the standing pilot light of your water heater frequently goes out, referring to the provided article and following the troubleshooting tips can be helpful in resolving the issue.

Regular maintenance plays a significant role in ensuring that all components are functioning properly and the water heater operates without interruptions. It is recommended to inspect the main burner and ignition system at least once a year. Clean any debris, soot, or deposits that may have accumulated on the igniter or flame rods, if necessary. This helps maintain optimal performance and reliability.


What Are the Advantages of Hot Surface Ignition in Gas Water Heaters?

Hot surface ignition offers several advantages. Firstly, it eliminates the need for a standing pilot light, making it more energy-efficient since there is no continuous flame burning. It also eliminates the risk of a pilot light going out, ensuring more reliable ignition. Additionally, hot surface igniters tend to have a longer lifespan compared to traditional pilot lights, reducing the need for frequent maintenance or replacements.

Can I Relight the Pilot on My Gas Water Heater if I Smell Gas in the Area?

No, if you smell gas near your gas water heater, it is essential to follow safety precautions. Avoid any open flames, sparks, or electrical switches, and evacuate the area immediately. Contact your gas utility provider or a qualified professional to assess and address the gas leak before attempting to relight the pilot.

Can I Use a Matchstick or a Regular Lighter to Light the Gas Burner on My Water Heater?

It is generally recommended to use a long-reach lighter or an igniter specifically designed for lighting gas appliances. These tools provide a safer distance between your hand and the burner, reducing the risk of burns or accidents. Matches or regular lighters with short flames may not reach the burner properly and can be hazardous. Always follow the manufacturer’s instructions and use the recommended tools for lighting the gas burner.

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