Does a tankless water heater require electricity?
A common assumption is that a gas tankless water heater runs on gas alone, so it would keep working during a power outage. In reality, nearly every modern tankless unit needs electricity, even the gas-fired ones.
The reason is that today’s tankless heaters rely on electronic ignition, control boards, and safety sensors rather than an old-fashioned standing pilot light. All of that needs power. And electric tankless models, naturally, run entirely on electricity.
HeatLand has installed and serviced tankless systems across Metro Vancouver and the Fraser Valley since 1999. Here’s exactly what electricity a tankless unit needs, what it means during an outage, and how power requirements differ between gas and electric models.
Why even gas tankless units need power
Older water heaters often used a standing pilot light, a small flame that burned continuously and could ignite the burner without any electricity. Modern tankless units have moved away from that design for efficiency and safety.
Instead, a gas tankless heater uses electronic ignition to light the burner only when hot water is called for, an electronic control board to manage temperature and flow, a fan to assist combustion and venting, and sensors that monitor conditions and shut the unit down if something is wrong. Every one of those components needs electricity.
The amount of power is modest, typically a standard household outlet is enough for a gas unit, but it is not optional. Without it, the ignition won’t fire, the fan won’t run, and the safety systems won’t function, so the unit simply won’t produce hot water. This is a key difference from the old pilot-light tanks some homeowners remember.
What happens during a power outage
Because a gas tankless unit depends on electricity for ignition, controls, and its combustion fan, it will not operate during a power outage. When the power drops, the unit shuts down and you lose hot water until power returns, even though your gas supply is unaffected.
This surprises homeowners who expected a gas appliance to keep working through an outage. In Metro Vancouver, where winter storms can knock out power, it’s a real consideration, though hot water is rarely the most urgent concern during an outage.
If uninterrupted hot water matters to you, options include a battery backup or a standby generator sized to power the unit’s modest electrical draw. Some homeowners who prioritize outage resilience weigh this alongside other backup needs like heating. It’s worth discussing with your installer so your expectations are set correctly and, if needed, a backup plan is in place before the next storm.
Electric tankless power requirements
Electric tankless units are a different story entirely, because they use electricity not just for controls but to actually heat the water. That takes a lot of power. A whole-home electric tankless unit typically requires one or more dedicated high-amperage circuits and significant electrical panel capacity.
In many homes, especially older ones, the existing panel may not have enough spare capacity to support a whole-home electric tankless unit without an upgrade. This is a critical thing to verify before choosing an electric model, since undersized wiring or an overloaded panel is a fire hazard.
Electric tankless units shine where gas venting is impractical, such as condos, and for point-of-use applications serving a single fixture. But their electrical demand is substantial. A licensed electrician or technician must confirm your panel and circuit capacity can safely support the unit. Never attempt high-amperage circuit work yourself; it must be done to code by a qualified professional.
Quick Checklist
- Know that gas tankless units still need a power source
- Provide a working outlet for a gas unit’s controls
- Plan a backup (battery or generator) if outage resilience matters
- Verify panel capacity before choosing an electric tankless unit
- Have high-amperage circuit work done by a licensed professional
| Unit Type | Electrical Need | Runs Without Power? |
|---|---|---|
| Gas tankless | Standard outlet for controls/ignition | No |
| Electric tankless | Dedicated high-amp circuit(s) | No |
| Old pilot-light tank | None | Yes |
Frequently Asked Questions
Will my gas tankless heater work during a power outage?
No. A gas tankless unit needs electricity for its ignition, control board, and combustion fan, so it shuts down when the power goes out, even though gas is still available. If you want hot water during outages, you’d need a battery backup or generator to power the unit’s modest electrical draw.
How much electricity does a gas tankless heater use?
A gas tankless unit uses only a small amount of electricity, enough to run its ignition, controls, sensors, and combustion fan, typically from a standard household outlet. This is very different from an electric tankless unit, which uses large amounts of power to actually heat the water itself.
Can my home’s panel handle an electric tankless heater?
It depends on your panel’s capacity. Whole-home electric tankless units need one or more dedicated high-amperage circuits and substantial panel capacity, which older homes may lack. A licensed professional must verify your electrical system before installation, since undersized wiring or an overloaded panel is a fire hazard.
Reviewed by the HeatLand Heating & Cooling team — licensed HVAC contractor serving Metro Vancouver & the Fraser Valley since 1999. This article is for general guidance only. If you smell gas, suspect a carbon monoxide leak, or are unsure about any electrical or gas component, stop troubleshooting immediately and call a licensed technician or 911.