How to Reset a Water Heater: Gas, Electric, Tankless

The Short Answer: It depends on the heater. An electric tank has a red high-limit (ECO) reset button behind the upper access panel. A gas tank has no reset button: you turn the knob to OFF, wait, and relight. A power-vent tank resets with its ON/OFF switch. A tankless heater resets from its control panel. A reset only helps once; if it trips again, something is wrong.

First: what tripped?

A reset is the end of a safety shutdown, not a repair. Before resetting anything:

• Smell gas? Don’t reset. Leave and call the gas utility or 911 from outside.
• Water on the floor, on the control, or in the burner area? Don’t reset until the source is found.
• Water was scalding before it stopped? That’s an overheat. The control or thermostat that allowed it needs checking.
• Is it the breaker? On an electric or power-vent heater, check the panel first. Reset a tripped breaker once. If it trips again, leave it off and call an electrician.

Electric tank: the red reset button

Electric tanks have a high-limit switch, also called the ECO (energy cut-off), on the upper thermostat. It opens if the water gets too hot and stays open until someone presses its red button.

Where it is: behind the upper jacket access panel and insulation, on the thermostat, next to live terminals. Rheem’s electric Use & Care manual (opens in a new tab) says that once the control opens, “it must be reset manually.”

What the manuals say: the button is reset with the power off, behind the access panel and insulation. Both manufacturers tie the reset to finding the cause. A. O. Smith’s electric Use & Care guide (opens in a new tab) says a tripped ECO “can usually be reset, but you should have a qualified person investigate the cause of the overheating,” and Rheem’s status-light chart says to “have a qualified technician reset the ECO.”

Our advice: because the button sits beside wiring, and because it only trips when something overheated, have an electrician or plumber reset it and find the cause. A. O. Smith says that in most cases a tripped ECO means the tank overheated because of a problem with one of the elements or thermostats. See why do I have to keep resetting my water heater.

Some newer electric and heat-pump models show a fault on a display instead. Read the code first and follow that model’s manual.

Gas tank: turn off, wait, relight

Standard gas tanks with a pilot don’t have an overheat reset button on the gas control. (On some Robertshaw controls the pilot button is labelled “Reset”; it’s part of the lighting procedure.) The “reset” is a relight:

1. Turn the gas control knob to OFF.
2. Wait. Labels usually give five minutes; on controls with a status light, wait until the light goes out.
3. Relight following the lighting instructions printed on the heater, then turn the knob to your temperature setting.

On controls with a status light, read the flash count first. On the Resideo (Honeywell) and White Rodgers electronic controls used by Bradford White and others, four flashes means the water overheated; check the label for your control’s codes. Bradford White’s service manual (opens in a new tab) says the Resideo (Honeywell) and White Rodgers electronic controls it uses have an ECO that resets with this OFF-and-wait sequence. If it overheats again after one relight, turn the control off and call for service; the manuals treat a repeat as a failed gas control. On older mechanical controls, an opened ECO can’t be reset at all: State’s service handbook (opens in a new tab) says “the entire control must be replaced.” Brand details are in Honeywell gas control reset and Rheem 9 red flashes.

The thermal switch. Flammable-vapor-resistant (FVIR) gas tanks, the standard design today, have a resettable thermal switch at the burner compartment, often on the inner door. It shuts off the gas when the combustion chamber overheats. State’s handbook lists the causes as flammable vapors (such as spilled gasoline), a blocked vent, or not enough combustion air. That’s why it isn’t an owner reset: the switch tripped for a reason that can be dangerous. Bradford White’s manual says a flammable vapor incident means replacing the water heater. See water heater thermal switch won’t reset.

Power-vent gas tank

Power-vent tanks have a blower on top and plug into an outlet. Their electronic controls lock out after repeated failures. State’s power-vent manual (opens in a new tab) says to slide the ON/OFF switch to OFF, wait 10 seconds, and switch it back on. It also warns that if the cause hasn’t been corrected, “the control will remain or again go back into lockout.” Bradford White’s power-vent controls retry on their own after a soft lockout; other lockouts have their own restart steps in the manual, and a flammable-vapor or overheat lockout needs a technician. Check the outside vent for snow, leaves or nests before resetting. See gas hot water heater power vent problems.

Tankless water heater

Tankless heaters reset from the control panel or remote, and the method varies by brand. Most also clear a code once its cause is fixed. Brand guides:

• How to reset a Navien tankless water heater
• How to reset a tankless water heater (Rinnai, Rheem, Noritz and others)
• How to reset a Takagi tankless

When a reset isn’t the answer

• It trips again within hours or days. The reset worked; the cause is still there.
• The breaker trips. That usually points to an electrical fault, such as a shorted element or wiring, which the high-limit can’t fix. Call an electrician.
• A gas tank shows the same fault again after relighting. Note the flash count and call for service.
• The thermal switch on a gas tank tripped. Look for stored fuel or solvents near the heater and a blocked vent, and have it inspected.

Frequently Asked Questions

Q: Where is the reset button on a gas water heater? A: There usually isn’t one on the gas control. You reset by turning the knob to OFF, waiting, and relighting. The red button some owners find inside the burner door is the thermal switch, which trips for safety reasons and should be reset only after a technician finds the cause.

Q: Why does my electric water heater reset button keep tripping? A: The high-limit trips when the water overheats. A. O. Smith says that’s usually a problem with one of the elements or thermostats. Finding which one means testing with a meter, which is technician work.

Q: How long after resetting should I have hot water? A: An electric tank heats a full tank in about 2 to 2½ hours, a gas tank in about an hour. See how long a water heater takes to heat up.