Why is my electric water heater not heating?

A standard tank has two heating elements, one high and one low. Bradford White's service manual describes the usual "non-simultaneous" design as one that "Allows only one heating element to operate at a time." When the tank is cold, the upper element runs first and heats the top of the tank. Once the upper thermostat is satisfied, power moves to the lower element, which heats the bottom portion.

That split explains the symptoms. Bradford White's troubleshooting chart lists these probable causes of no hot water: no power to the heater, loose wire connections, an inoperative upper heating element, an inoperative upper thermostat, or an open ECO (the high-limit switch). For not enough hot water, the chart starts with an inoperative lower heating element and also lists a thermostat set too low, lime build-up on the elements, high demand, an undersized heater, very cold inlet water and a damaged dip tube.

Work in this order. The first few steps need no tools and no panel.

1. 1Look at the breaker. Rheem's chart says that if a fuse is blown or a breaker tripped, replace the fuse or reset the breaker. Reset once. If it trips again, leave it off and read why an electric water heater keeps tripping the breaker.
2. 2Check the switch and the house. Rheem says to make sure the electric supply and any disconnect switch are in the ON position, and to contact the local electric utility if service to your home may be interrupted.
3. 3Close every hot faucet. Rheem lists leaking or open hot water faucets as a cause of not enough or no hot water.
4. 4Give it time after heavy use. Rheem's advice: "Wait for the water heater to recover after an abnormal demand." Our page on why you run out of hot water fast covers sizing.
5. 5Check the thermostat setting. Rheem and Bradford White both list a thermostat set too low. A. O. Smith says to set both thermostats to 120 degrees F, and warns that higher tank temperatures increase hot water delivery but also increase the risk of scalding.

### What does the red reset button do?

That button is the ECO, the high-limit safety cutoff. Rheem says the ECO sits above the upper heating element and breaks the power circuit to the element if the water temperature becomes excessively high. Rheem adds: "Once the control opens, it must be reset manually."

Turn the breaker off before you open anything. A. O. Smith warns that breakers can be mismarked, so its guide says to check the incoming wires with a voltmeter. If you aren't comfortable working near live wiring, stop here and get help.

A. O. Smith says that if the button clicks when pressed, the water heater got too hot and tripped the energy cutoff. Rheem says a qualified service technician must investigate the cause of that high temperature before the heater goes back into service. Bradford White says repeated ECO trips are usually the result of a grounded element.

If the button does not click, A. O. Smith's chart moves on to the upper heating element, then the upper thermostat. Those are resistance tests, covered in how to test a water heater element.

### Sediment and a dry tank

Yes, it can be. Bradford White says slow hot water recovery can usually be traced to sediment or lime build-up around a heating element, and that build-up can also cause an air pocket and a dry-fired element that stops working. Our page on flushing a water heater in Phoenix covers the routine.

One rule matters more than the rest: Rheem says not to turn on the water heater unless it is filled with water.

### Plumbing instead of the heater

Sometimes the heater is fine. A. O. Smith says to make sure the water heater is not undersized, and notes that seasonal variations in cold water temperatures and hot water usage can generate "not enough hot water" complaints. It also says faulty shower controls or defective thermostatic mixing valves can cause the same symptom.

Bradford White's chart adds two plumbing causes to the not-enough-hot-water list: plumbing connections reversed, and a damaged dip tube. Rheem also lists colder inlet water in the winter months. Its chart says this is normal, and that the colder inlet water takes longer to heat.

A quick way to sort it out: if one shower or one faucet is the only problem, look at that fixture first. Our page on hot water only missing in the shower covers that case. If every hot tap is cold, the heater is the suspect.

Knowing the order a technician follows shows why the first steps above are worth your time. Bradford White's "Quick Step Plan to Hot Water" runs like this:

1. 1Turn off power to the water heater and check that all wire connections are tight and corrosion-free.
2. 2Turn the power on and determine that service voltage is present and the high limit (ECO) has not actuated.
3. 3Check for an inoperative heating element.
4. 4Check for proper thermostat operation.

A. O. Smith's chart for a heater with no hot water is similar. It starts by checking for power at the top two screws of the upper thermostat, and if 240V is not present, it checks the circuit breaker and wiring. If the reset button did not click, it tests the upper element's resistance. A. O. Smith says a good element reads between 5 and 25 ohms, with 12.5 ohms typical. If the upper element is good, the chart says to replace the upper thermostat.

For the lukewarm case, A. O. Smith's guide checks the lower element and says that if the lower element is good, replace the lower thermostat. If both elements and thermostats test good, the guide says to check for a leak on the hot water side of the plumbing system.

A. O. Smith also gives a ground test: the meter reads OL if the element is not shorted or grounded, and lower resistance means the element is shorted or grounded and must be replaced.

Stop if the reset button clicks, the breaker trips again, you see water near the electrical parts, or you smell burning. Rheem says "Refer repairs to qualified service personnel," and lists electrical wiring, heating elements and other safety devices as things not to repair yourself.

### Which related page fits your problem?

Two nearby pages cover the neighbors of this one. If the breaker keeps tripping, start with why an electric water heater keeps tripping the breaker. If you have a gas heater, or you want the full list of causes across fuel types, see why you might have no hot water. This page is for the electric tank that has power, at least at the panel, and still won't heat.

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