Most tankless water heaters do not have pilot lights
Tankless water heaters work differently from storage tank models, and most do not use a pilot light at all. Instead, they rely on an electronic ignition system that lights the burner only when you turn on hot water. The moment you stop using hot water, the burner shuts off. This on-demand design is one reason tankless models use less energy than traditional tank heaters.
Some older tankless models or certain gas-powered units may have a small pilot light, but this is uncommon in modern equipment. If your tankless heater does have one, it will be much smaller than the pilot light in a storage tank water heater—often just a thin flame that ignites the main burner rather than burning continuously.
Key Takeaways
- Most modern tankless water heaters use electronic ignition instead of a pilot light, so there is no flame burning when you are not using hot water.
- Electronic ignition systems light the burner only when hot water is requested, then shut off when ready after use stops.
- If your tankless heater does have a pilot light, it is typically found only on older models or certain specialty units.
- Tankless heaters require electricity to power the ignition system, even if they are gas-powered, so a power outage will prevent them from working.
How electronic ignition works in tankless heaters
When you turn on a hot water tap, a sensor inside the tankless heater detects the water flow. This triggers an electronic ignition—usually a spark or hot surface igniter—that lights the gas burner. The burner heats the water as it flows through the unit, and the temperature is controlled by a thermostat. Once you close the tap and water stops flowing, the burner shuts off within seconds.
This system is more efficient than a pilot light because no gas is wasted keeping a flame alive when nobody is using hot water. The trade-off is that electronic ignition requires electricity. Even gas tankless heaters need power to run the ignition system, the control board, and the sensors. If your home loses power, your tankless heater will not work, even if you have gas available.
Why tankless heaters abandoned the pilot light design
Manufacturers moved away from pilot lights in tankless heaters for three main reasons: energy savings, safety, and reliability. A pilot light burns continuously and wastes gas even when nobody is using hot water. Over a year, this adds up to real money and fuel consumption. Electronic ignition eliminates that waste.
Pilot lights also require manual relighting if they blow out—a common problem in older units. Electronic ignition systems restart automatically when water flow is detected, so you do not have to troubleshoot a dead pilot. The systems are also more precise, allowing the heater to maintain exact water temperature without the fluctuations that sometimes occur with pilot-lit burners.
What to do if your tankless heater will not ignite
If your tankless heater is not producing hot water, the problem is usually not a pilot light but rather the electronic ignition system or a sensor. Start by checking that the unit has power—look for a power light on the control panel. If there is no light, check the circuit breaker or the outlet the heater is plugged into.
Next, confirm that water is flowing to the unit. Some tankless heaters have a minimum flow rate requirement; if the flow is too low (for example, from a single small tap), the sensor may not trigger ignition. Try opening a larger tap or multiple taps to increase flow. If the unit still does not ignite, the problem likely lies with the ignition electrode, the flame sensor, or the control board—all parts that require a technician to diagnose and replace.
Backup power options for tankless heaters
Because tankless heaters depend on electricity, a power outage will leave you without hot water even if you have gas service. Some homeowners install a battery backup system or connect the heater to a small uninterruptible power supply (UPS) to keep the ignition system running during brief outages. These systems are not expensive but do require planning before installation.
Another option is a whole-home generator, which will power the tankless heater along with other essential appliances during an outage. If you live in an area with frequent power interruptions, discussing backup power with your installer before purchase can help you choose the right solution for your situation.
Differences between tankless and storage tank pilot lights
A traditional storage tank water heater often has a pilot light that burns all day and all night, keeping the main burner ready to ignite whenever the water temperature drops. This pilot light is visible through a small window on the tank and is usually about the size of a pencil flame. If it blows out, you have to relight it manually by following the instructions on the tank.
A tankless heater, by contrast, has no continuously burning flame. If the unit is older and does have a pilot light, it serves only to ignite the main burner and is much smaller. Modern tankless heaters skip the pilot light entirely and use electronic ignition instead. This is one of the key differences that makes tankless heaters more energy-efficient than storage tank models.
Frequently Asked Questions
Can I relight a pilot light on my tankless water heater?
Most modern tankless heaters do not have a pilot light to relight. If your unit is older and does have one, the relighting process is similar to a storage tank heater: turn the control knob to "Pilot," hold down the ignition button, and light the flame with a match or lighter. Consult your owner's manual for the exact steps, as procedures vary by model.
What happens to my hot water during a power outage?
Your tankless heater will not produce hot water during a power outage because the electronic ignition system requires electricity. You will have cold water only. If you have a battery backup system installed, it may keep the heater running for a short time, depending on the battery capacity.
Is a tankless heater without a pilot light safer?
Electronic ignition systems are generally considered safer than pilot lights because there is no open flame burning continuously. The burner only ignites when water is flowing, reducing the risk of accidental gas leaks or flame-related hazards. However, all gas appliances carry some risk and should be installed and maintained by may have access to professionals.
Do all gas tankless heaters need electricity?
Yes, even gas-powered tankless heaters require electricity to operate the ignition system, control board, and sensors. Some models can run on batteries for a limited time if power is lost, but they cannot function without any electrical power source.
How do I know if my tankless heater has a pilot light?
Check your owner's manual or look at the control panel on the unit. If you see a small window or access point with a visible flame, your heater has a pilot light. Most heaters made in the last 10 to 15 years use electronic ignition and will not have a visible pilot light.