Efficient and Reliable: The Power of Hot Surface Ignitors for Water Heaters

Water heaters play a crucial role in our daily lives, providing hot water for various purposes. Within these systems, the ignition process holds paramount importance, ensuring reliable and efficient operation.

In recent years, hot surface ignitors (HSIs) have gained popularity as a superior alternative to traditional ignition systems such as pilot lights and piezo ignition.

This article explores the advantages and disadvantages of hot surface ignitors, discussing their working principle, common problems and troubleshooting techniques, testing, replacing, and a comparison to other ignition systems.

Hot Surface Ignitors for Water Heaters: Considerations and Benefits

What Are Hot Surface Ignitors, and How Do They Work?

photo: amazon.com

Hot surface ignitors are heating elements specifically designed to initiate combustion in various heating systems, including gas water heaters.

They operate through a simple yet effective process. When the water heater calls for heat, the ignitor control module activates, providing electrical current to the silicon carbide or silicon nitride heating element.

The element heats up rapidly, reaching a temperature that can ignite the fuel gas directly upon contact. The gas valve opens, allowing the fuel to flow, and the hot surface ignitor ignites the gas, initiating the combustion process.

Are They Safe?

Hot surface ignitors incorporate safety features to prevent gas leaks and potential hazards. These safety measures often include flame sensing capabilities and safety shut-off mechanisms. The elements should be installed, operated, and maintained in accordance with safety guidelines and local building codes.

Many HSIs include a flame sensor as a safety measure. The flame sensor detects the presence of a flame once the gas ignites. If the flame sensor does not detect a flame within a specified timeframe, it signals the control module to shut off the gas supply, preventing the accumulation of unburned gas and potential hazards.

In addition to the flame sensor, modern water heaters often have safety mechanisms that shut off the gas supply if any abnormal conditions are detected. This can include excessive heat, flame failure, or other potential safety risks.

Common Problems and Troubleshooting Tips

While hot surface ignitors are generally reliable and widely used in gas water heaters, they can experience certain issues that may require attention or maintenance.

Here are some common problems and troubleshooting tips:

  1. Ignition failure: Check the power supply to ensure it is functioning properly. Inspect the ignitor for wear, cracks, or damage. Clean it to remove any debris. Verify the positioning of the part and ensure it is close to the burner assembly. Check the gas supply to ensure there is enough gas for ignition.
  2. Intermittent ignition: Inspect the wiring connections for any loose or damaged wires. Clean the ignitor and surrounding area to remove debris. Verify that the flame sensor is clean and properly positioned. Monitor the voltage supplied to this element and address any fluctuations or power supply issues.
  3. Uneven or delayed ignition: Inspect the ignitor for wear, cracks, or damage. Clean it to remove debris. Adjust the positioning of the ignitor to ensure proper alignment with the burner assembly. Check the gas pressure to ensure it is within the recommended range.
  4. Ignitor not heating: Check the electrical connections to ensure they are secure and undamaged. Verify the power supply to the ignitor. Test its resistance using a multimeter. If the reading is infinite, consider replacing it. If troubleshooting steps do not resolve the issue, consult a professional technician.

If you suspect that there is a problem, test the element.

How to Test a Hot Surface Ignitor

Testing a hot surface ignitor allows you to verify its functionality, diagnose heating system issues, and ensure safe operation. By conducting tests, potential problems can be identified early, preventing unexpected breakdowns. It is also a cost-effective troubleshooting step that helps pinpoint this element as the source of the problem. Additionally, testing helps determine if it needs replacement, saving time and effort on unnecessary troubleshooting steps.

To test a hot surface ignitor, follow these steps:

  1. Safety first: Prior to conducting any testing or inspection, ensure the power supply to the heating system is turned off to prevent accidents or electrical shocks.
  2. Access the ignitor: Locate the hot surface ignitor within your heating system. This may require removing a panel or access cover to reach this part.
  3. Resistance measurement: Using a multimeter set to resistance or ohms mode, you can test the electrical continuity of the ignitor. Remove it from the system and disconnect any wiring connections. Touch the multimeter probes to the two electrical terminals of the ignitor, ensuring a secure connection. A good silicon nitride hot surface ignitor should have a resistance reading between 30 to 75 ohms (depending on the manufacturer and model). If the measurement falls within this range, the ignitor is functioning properly. If the resistance reading exceeds 75 ohms, it indicates a failing or failed hot surface ignitor.
  4. Visual confirmation of glow: For additional confirmation, you can visually test the ignitor’s ability to glow when powered. Reconnect the ignitor to its wiring and restore power to the heating system. Observe it closely for a bright orange glow. A properly functioning ignitor should exhibit this glow. If there is no glow or only a faint glow, it suggests a problem with the element.
  5. Interpreting resistance readings: If the multimeter shows a reading of 0 or ∞ (infinity), or no reading at all, it signifies a broken resistance, indicating that the ignitor is faulty and needs to be replaced.

Things to Consider When Replacing a Hot Surface Ignitor

When replacing a hot surface ignitor, there are several important factors to consider to ensure a successful and safe replacement. Here are some key things to keep in mind:

  1. Compatibility: Ensure that the replacement ignitor is compatible with your water heater type and model. They come in various shapes, sizes, and electrical specifications, so it’s crucial to match the replacement with the original specifications to ensure proper fit and function.
  2. Type and material: Consider the type and material of the ignitor.
  3. Voltage and current rating: Verify that the replacement ignitor has the correct voltage and current rating. This information is usually provided on the part itself or in the system’s documentation. Using one with an incorrect voltage or current rating can lead to improper heating or even damage to the system.
  4. Quality and reliability: Choose a high-quality replacement element from a reputable manufacturer. Investing in a reliable and durable ignitor will ensure long-term performance and minimize the need for frequent replacements.
  5. Installation: Follow the manufacturer’s instructions and any applicable safety guidelines when installing or replacing one.
  6. Testing and verification: After installation, test the newly replaced ignitor to ensure it is functioning correctly. Observe the ignition sequence and check for the presence of a stable flame. Monitor the system for any abnormal behavior or issues that may arise after the replacement.

Replacement: Step-by-Step Instructions

However, please note that specific instructions may vary depending on your water heater type and model.

  1. Turn off the power: Before starting any work, ensure that the power to your heating system is turned off at the circuit breaker or main electrical panel.
  2. Locate the hot surface ignitor: The ignitor is usually located near the burner assembly. Refer to your heating system’s documentation or consult a professional if you’re having trouble finding it.
  3. Disconnect the electrical connections: Carefully disconnect the electrical connections to the ignitor. These connections may include wires, plugs, or connectors. Take note of the arrangement or take a picture to help with reinstallation.
  4. Remove mounting screws or clips: The ignitor is typically held in place by screws or clips. Remove these fasteners to release the part from its mounting bracket or housing. Keep track of the removed hardware for reassembly.
  5. Remove the old ignitor: Gently pull out or slide the old ignitor out of its position. Be cautious not to damage any surrounding components or wiring.
  6. Install the new ignitor: Take the new ignitor and carefully slide it into the same position as the old one. Ensure it aligns properly with the mounting bracket or housing.
  7. Reattach mounting screws or clips: Secure the new part in place by reattaching the mounting screws or clips. Tighten them securely but avoid over-tightening to prevent damage.
  8. Reconnect electrical connections: Reconnect the electrical connections to the new ignitor, ensuring they are properly secured and aligned. Double-check the arrangement with your notes or reference photo.
  9. Restore power and test: Turn the power back on at the circuit breaker or main electrical panel. Start the heating system and observe the ignition sequence to verify that the new ignitor is functioning correctly. Ensure the flame is stable and consistent.

How Proper Positioning Is Important for Optimal Performance

Proper positioning of the ignitor within the water heater is crucial for its optimal performance, reliable, and safe operation. Here are some guidelines for the placement of the part:

  1. Close proximity to the burner assembly: The hot surface ignitor should be positioned in close proximity to the burner assembly of the water heater. This allows for efficient heat transfer from the element to the fuel gas, promoting reliable ignition.
  2. Clearance from other components: Ensure that the ignitor has sufficient clearance from other components, such as gas lines, wiring, or insulation. This helps prevent any potential damage to the element or interference with its operation.
  3. Correct orientation: It should be positioned correctly according to the manufacturer’s instructions. Follow any specific guidelines regarding the orientation, alignment, or mounting to ensure proper functioning.
  4. Secure attachment: It should be securely attached or mounted in its designated location within the water heater. This prevents any movement or displacement that could affect its performance or compromise its safety.
  5. Adherence to manufacturer’s instructions: Always refer to the water heater’s instruction manual or the specific guidelines provided by the manufacturer for the recommended positioning and installation steps. Each water heater model and ignitor type may have specific requirements that need to be followed.

It is important to note that the positioning of the ignitor may vary depending on the specific design and configuration of the water heater.

Comparing Hot Surface Ignitors to Other Ignition Systems

Here’s a side-by-side comparison of hot surface ignitors, pilot lights, and piezo ignition, the most common ignition systems used in gas water heaters:

Hot Surface Ignitors: Advantages

  • Hot surface ignitors (HSIs) do not require a continuously burning flame, resulting in reduced energy consumption and lower utility bills.
  • They provide consistent ignition without the risk of pilot lights going out due to drafts or other factors, ensuring reliable operation and an uninterrupted hot water supply.
  • HSIs often incorporate safety features such as flame sensors and safety shut-off mechanisms, enhancing safety by detecting and responding to flame failure or abnormal conditions.
  • They eliminate the need for manual relighting, making operation more convenient for users.
  • Although HSIs may have a higher upfront cost compared to pilot lights, long-term energy savings, and increased reliability can result in cost savings over the life of the appliance.

Hot Surface Ignitors: Disadvantages

  • Hot surface ignitors rely on an electrical power supply, which means they require a power source and proper wiring connections during installation.
  • While they are generally reliable, they may require occasional inspection and cleaning to ensure optimal performance.

Pilot Lights: Advantages

  • Pilot lights are a traditional and straightforward ignition method, relying on a continuously burning flame.
  • Pilot lights do not require an electrical power supply, making them suitable for situations where electricity is unavailable or unreliable.
  • They have been used for many years and have a proven track record of functionality.

Pilot Lights: Disadvantages

  • Pilot lights consume fuel continuously since the flame needs to burn at all times, resulting in higher energy consumption and increased utility costs.
  • Pilot lights can go out due to drafts, interruptions in gas supply, or other factors, requiring manual relighting.
  • They can pose safety risks if the flame goes out unnoticed, leading to the accumulation of unburned gas and potential hazards.

Piezo Ignition: Advantages

  • Piezo ignition systems generate sparks using mechanical force, eliminating the need for an electrical power supply.
  • Piezo ignition systems are relatively simple and do not require complex electrical connections or components.
  • They produce sparks instantly, resulting in quick and reliable ignition.

Piezo Ignition: Disadvantages

  • Like pilot lights, piezo ignition systems require a continuously burning flame to maintain ignition, leading to higher energy consumption and increased utility costs.
  • These systems can be prone to failure or degradation over time, requiring repair or replacement.
  • Piezo ignition systems generally lack built-in safety features, such as flame sensors or automatic shut-off mechanisms, making them potentially less safe compared to HSIs.


Hot surface ignitors have revolutionized the ignition process in water heaters, offering enhanced efficiency and reliability. With their ability to eliminate the need for pilot lights, HSIs improve energy consumption while ensuring consistent ignition.

Proper installation, regular maintenance, and adherence to safety regulations are vital for their optimal performance. As technology advances, we can anticipate further developments in ignition systems, optimizing water heater efficiency and delivering reliable hot water when we need it most.


Why Is My Hot Surface Ignitor Not Glowing?

If a hot surface ignitor is not glowing, it may be due to various factors. Common causes include issues with the power supply, a faulty or worn-out element, improper grounding, loose or damaged wiring, problems with the control board, or gas supply issues. To resolve the problem, check the power supply, inspect the ignitor for damage, ensure proper grounding, examine the wiring connections, consider control board troubleshooting, and verify the gas supply.

Are Hot Surface Ignitors Interchangeable?

Hot surface ignitors are generally not interchangeable across different models or manufacturers. While there may be some cases where compatibility exists, it is important to use the specific model recommended by the manufacturer of your heating system. Hot surface ignitors vary in terms of their physical dimensions, electrical characteristics, and compatibility with the control system of the heating equipment. Using an incorrect or incompatible part can result in improper operation, potential damage to the equipment, and compromised safety.

Can I Clean a Hot Surface Ignitor?

Hot surface ignitors are typically not designed to be cleaned. They are made of delicate materials, such as silicon nitride or silicon carbide, which can be easily damaged or compromised by cleaning attempts. It’s best to avoid cleaning the element unless specifically mentioned in the manufacturer’s instructions.

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