Electric water heater not heating? Breaker, reset button, then the elements

Last verified: Oct 26, 2026

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Safety first. Electric water heaters run on 240-volt power. A.O. Smith says to "turn off power at the circuit breaker before touching anything. High-voltage electricity can kill, and water heater components remain live even when the unit isn't actively heating." [1] Let the heater cool before you take off panels, and keep clear of the relief valve: scalding water can shoot out. [1] Rheem says to turn off the breaker if the heater has been through overheating, fire, flood or physical damage, or if the ECO (the high-temperature cutoff) fails to shut it off. [3] Wiring, element and thermostat replacement are for a qualified technician. [3][4] If you're not comfortable, call a licensed plumber. [1] These are general steps; your model's manual comes first.

Cold showers are a top complaint every fall. Most electric tanks work the same way. They have two heating elements, each with its own thermostat, and the red reset button sits on the upper thermostat. [1][4] Here's the order the manufacturers' own guides follow, starting with the free checks.

Step 1: The free checks (no tools)

Circuit breaker. A.O. Smith calls a tripped breaker "the most common reason" an electric tank isn't heating, and says to check the panel first. [1] Rheem's chart adds blown fuses, a disconnect switch next to the heater that's turned off, and a power outage from the utility. [3] If the breaker trips again right after you reset it, stop. Bradford White says a heating element shorted to ground will "in most cases" trip the breaker. [4] That needs a technician or a meter test (Step 3).
Thermostat set too low. Rheem and Bradford White both list this. [3][4] A.O. Smith suggests 120°F as the best balance of heating speed, energy cost and safety. [1]
A faucet left open or leaking. Rheem says to make sure all faucets are closed. [3]
You just ran it out. After a lot of hot water use, Rheem says to "wait for the water heater to recover." [3] A.O. Smith says electric tanks need 60–90 minutes to recover, compared with 30–40 for gas. [1] In winter, colder incoming water also takes longer to heat. Rheem calls that normal. [3]

Step 2: Press the red reset button (once)

The reset button is the Energy Cut Off (ECO), a high-temperature safety switch. It cuts power to the elements if the water gets too hot, and it has to be reset by hand. [1][3] A.O. Smith's steps: [1]

Turn off power at the breaker.
Remove the access panel over the upper thermostat. (Rheem also has you move the insulation aside.) [3]
Press the red reset button firmly. If it clicks, the heater overheated and tripped the safety switch.
Put the insulation and cover back before you restore power, then test for hot water. [3]

If it trips again, don't keep resetting it. A.O. Smith says repeated tripping "indicates serious problems like shorted elements or faulty thermostats." [1] Bradford White says repeated ECO trips are "usually the result of a grounded element." [4] Rheem says the cause of the overheating must be investigated by a qualified service technician before the heater goes back into service. [3]

Step 3: Find the bad element or thermostat

Bradford White's service manual says element failure is the most common cause of electric water heater trouble, so check the elements first. [4] These are the meter tests from the A.O. Smith and Bradford White technician guides. They're written for qualified service people, and the voltage check is done with the power on. [2][4] If you don't own a multimeter or haven't used one on 240 volts, hand this list to your plumber.

Is power reaching the heater? A.O. Smith checks for 240V at the top two screws of the upper thermostat. If it's not there, check the breaker and wiring. [2]
Burned-out (open) element. With the power off and the wires removed, measure across the element's two screws. A.O. Smith says a good element reads between 5 and 25 ohms (12.5 typical). [2] Bradford White gives 12.8 ohms (±6%) for a 240-volt, 4,500-watt element, using ohms = volts² ÷ watts. [4] The element's voltage and wattage are stamped on its terminal block. [4] A reading outside the range means the element must be replaced. [2][4]
Grounded (shorted) element. Measure from each screw to the metal flange or tank. Any reading means a grounded element. [4] A.O. Smith says the meter should read OL. [2]
Thermostats. If the reset button did not click and the upper element tests good, A.O. Smith's chart says to replace the upper thermostat. [2] If it did click and both elements are good, A.O. Smith says the thermostat contacts are probably welded shut. Because the lower thermostat "does most of the work," it's the most likely to fail. [2]

Hot water runs out fast? Probably the lower half

Bradford White explains that in the usual setup only one element heats at a time. The upper element heats the top of the tank first, then power switches to the lower element. [4] So when the lower element or thermostat dies, you often still get a little hot water from the top of the tank. For "not enough hot water," Bradford White lists: [4]

A failed lower element, a thermostat set too low or not working, or loose wires
Sediment or lime buildup on the elements
A heavy-use period, or a heater too small for the household
Very cold inlet water
Hot and cold connections installed backwards, or a damaged dip tube

Slow recovery "can usually be traced back to sediment or lime build up around" an element, and hissing or "singing" elements mean lime on the elements. [4] A.O. Smith suggests draining a few gallons once a year to flush out sediment, and more often in hard-water areas. [1]

Drained the tank and now it won't heat? Dry firing

If the element came on before the tank was full, it can burn out in seconds. Bradford White calls this dry firing. An element that's partly or completely out of water fails, and sediment can trap an air pocket around an element with the same result. Its rule: make sure the tank "is full of water prior to energizing the water heater." [4] Rheem: "The tank must be full of water before heater is turned on." Its warranty doesn't cover damage from running with an empty or partly empty tank. [3] To refill, Rheem says to close the drain valve, open the cold water supply, and open hot faucets until a steady flow runs from each. Only then turn the power back on. [3]

When to stop and call

The breaker or the reset button trips again after one reset. [1][4]
The heater has been through flooding, fire, overheating or physical damage. Rheem says to turn off the power and water and not run it until a qualified technician checks it. [3]
The tank itself is leaking. A.O. Smith says that usually means replacing the heater. [1]
Any element, thermostat or wiring work you're not trained for. [3][4]

Have your model and serial number (on the rating plate) ready so you get the right manual and parts.

Other no-heat guides

Gas tank instead? See gas water heater pilot won't stay lit. In an RV, the water heater is a different system: see RV furnace and water heater not working. House heat: heat pump blowing cold air · gas furnace blowing cold air.

FAQ

Where is the reset button? On the upper thermostat, behind the upper access panel and insulation. [1][3]

Why did my reset button trip? The water overheated. [1][2] Bradford White says repeated trips usually mean a grounded element, and A.O. Smith also points to stuck thermostat contacts. [2][4]

How long until I have hot water again? A.O. Smith says electric tanks need 60–90 minutes to recover. [1] It takes longer when the incoming water is cold. [3]

We don't list part prices, repair costs, or element ratings for models not covered by the cited manuals. Check your own heater's rating plate and manual.

Sources

General diagnostic guidance only, not specific to any single model. Sourced from the A.O. Smith, Rheem and Bradford White pages and manuals linked above. Last verified Oct 26, 2026.