Water Heater Reset Button: Where It Is and When to Press It

What the reset button actually is

A.O. Smith calls it the Energy Cut Off, the high-limit safety switch. Techs often shorten that to ECO. It's a safety switch built into the upper thermostat that cuts power to both elements when the tank gets dangerously hot. It doesn't reset itself. Someone has to press it, which is the point: it forces you to notice that something went wrong.

Gas tank heaters generally don't have a red reset button like this. Their high-limit protection is built into the gas control valve, and the "reset" people talk about on gas heaters is relighting the pilot. Tankless units reset through the controller or by cycling power.

Tools and parts

• A screwdriver for the access panel screws (a small nut driver or a Phillips fits most)
• A non-contact voltage tester, to confirm power is off
• A flashlight
• Gloves, since the panel edges are sharp

You don't need parts just to reset. If it keeps tripping, you'll likely need an element, a thermostat or both, covered below.

How to reset an electric water heater

If the red button didn't click, it wasn't tripped. Go back to the breaker, then look at the elements. Our no hot water from an electric water heater page covers that path.

Why it tripped

The ECO trips when the water gets hotter than it should. A.O. Smith says that's often caused by a grounded element or a faulty lower thermostat. A few of the usual reasons:

• A thermostat stuck closed. It keeps feeding power to an element after the tank is up to temperature.
• A grounded element. The element's sheath has failed, and current leaks to the tank, which can keep it heating with the thermostat open.
• Loose wiring at the thermostat or element terminals, which can heat up and trip the switch.
• A tired ECO. The switch itself can wear out and trip early. Rule out the others first.

A.O. Smith says repeated tripping calls for a professional. Here's why it matters: the ECO is the backstop before the T&P valve. If it keeps tripping and you keep pressing it, you're leaning on the last safety device in line.

Common mistakes

• Resetting with the power on. That's how people get shocked. Breaker off first.
• Pressing it again and again. One reset is a test. A second trip means a failed part.
• Turning the thermostat way up afterward. A.O. Smith recommends 120°F for most homes. Raising it adds scald risk and doesn't fix a fault.
• Running an electric heater with an empty tank. If you drained it, refill it completely before you turn the breaker on. Dry elements can burn out.
• Confusing the breaker with the reset. A tripped breaker and a tripped ECO look the same at the faucet. If the breaker trips again, that's a short. See breaker keeps tripping.

Resetting a gas water heater pilot light

On a standing-pilot gas heater, "reset" usually means relighting the pilot. The steps are printed on the label on the tank, and you should follow your model's version exactly. In general you turn the control to the pilot position, hold the knob down while you light the pilot (or press the igniter), keep holding for a short time so the thermocouple heats, then release and turn the control to on.

If the pilot won't stay lit after you let go, the thermocouple is the usual suspect. See pilot light won't stay lit. If the pilot stays lit but the water stays cold, read pilot light is lit but no hot water.

Some gas heaters use an electronic gas control with a status light instead of a standing pilot. If the light is off or blinking, check the code on the label or in the manual. Many of these restart by turning the control off, waiting a few minutes and turning it back on, but follow the manual for your model.

How to reset a tankless water heater

Tankless units don't have a red reset button. They show a code, and the reset depends on the code. In Rinnai's service manual, some codes clear by pressing the ON/OFF button on the controller twice, and others need the power turned off and back on. Rinnai calls the power-off reset a hard reset.

Rinnai's manual also makes clear that a reset doesn't correct the cause. If it comes back, the underlying problem is still there. Code 11, which the manual ties to gas supply, igniter spark and flame rod checks, is one of them, and our page on Rinnai error code 11 walks through it.

When it's a pro job

Call a plumber or electrician if:

• The reset button trips a second time.
• The breaker trips when you turn the heater back on.
• You see scorched wires, melted insulation or a burnt smell behind the panel.
• You'd rather not work near line voltage. Plenty of people don't, and a plumber does this every week.

HomeGuide lists heating element replacement at $100 to $350 and thermostat replacement at $100 to $350. Many companies charge a service call fee of $50 to $200 on top. On an old heater, compare the quote against water heater cost before you decide.