Troubleshooting a Rheem Electric Water Heater

A Rheem electric tank runs on a 240-volt circuit, so a wrong guess inside the access panel can hurt you. Most "no hot water" calls come down to a handful of causes that don't need a screwdriver. The rest are parts that need a licensed person, and the sooner you know which is which, the less you spend.

This page follows Rheem's Use and Care manual for its electronic-control electric models and several Rheem articles. Rheem sells other electric models with dial thermostats behind separate access panels, and their steps differ. Find your model and serial number on the rating plate and look up the manual for your exact unit on Rheem's website before you open anything.

Safety first

• Power off before any cover comes off. Rheem's manual and its articles tell owners to switch the breaker off before working on the unit. Learn which breaker it is now, before you need it.
• Leave the repairs to a technician. The manual's caution is blunt: don't attempt repair of electrical wiring, temperature sensors, the electronic control, heating elements or other safety devices.
• Heater overheated, burned, flooded or damaged: turn off the breaker, and turn off the water to the heater too. Rheem says not to run it again until qualified service personnel have checked it.
• Burning smell, or a warm outlet or switch near the heater: stop using the circuit and have an electrician check it. The U.S. Consumer Product Safety Commission advises not using a warm outlet or switch.
• Strong rotten egg smell in the air: treat it as a gas leak until a gas company says otherwise. Leave, and call from outside or a neighbor's home. Don't use switches, the doorbell or anything that could spark. A sulfur smell that shows up only in hot tap water is a separate issue, covered under odor below.

No or not enough hot water

Rheem's troubleshooting chart lists these causes for no or little hot water. Work down the list in order, because the early items are the quickest to check.

1. Breaker or fuse. A blown fuse or tripped breaker is on Rheem's list. Reset the breaker once. If it trips again, don't keep resetting it (see the breaker section).
2. Supply switched off. Make sure the electric supply to the heater and any disconnect switch near it are on.
3. Heavy use. Rheem says water use may have exceeded the capacity of the heater. Wait for it to recover. A tank needs time to reheat after back-to-back showers.
4. Thermostat too low. Check the set point on the control.
5. A faucet running or leaking. Rheem's chart lists leaking or open hot faucets as a cause. Make sure every faucet is closed.
6. Cold weather. Colder incoming water in winter takes longer to heat. Rheem calls this normal.
7. Tripped high-limit (ECO). See the next section.
8. Auto shutoff valve closed. Only on units fitted with Rheem's leak-detection and shutoff option. Rheem says to turn the power off to the heater, then turn the valve knob counterclockwise until the arrow points to OPEN.
9. Electric service interrupted. Rheem says to contact the local electric utility if the supply to your home is interrupted.

If all of that checks out and there's still no heat, the cause is probably a failed element, thermostat or sensor. Those are the parts Rheem says to leave to a qualified technician. Have the model and serial number from the rating plate ready when you call.

Resetting the high-limit (ECO)

The ECO is a safety cutoff above the upper heating element. If the water gets excessively hot, it breaks the power circuit to the element and stays open until someone resets it by hand. Rheem's manual for the electronic-control model gives these steps:

1. Turn off the power to the water heater.
2. Remove the user interface control and the insulation behind it.
3. Press the red RESET button on the power board and upper sensor assembly.
4. Put the insulation and the user interface back before turning the power on.

The same manual says the cause of the overheat must be investigated by a qualified technician before the heater goes back into service. An ECO that has tripped once is a warning. One that trips again means something is wrong, probably the thermostat or an element, and you should stop resetting it. Rheem also says to turn off the breaker if the ECO fails to shut off. On older Rheem models the reset sits in a different place, so use the manual for your model.

Water too hot

Rheem's electronic models let you set the temperature between 110°F and 150°F. The manual warns that water above 125°F can cause severe burns or death from scalding, and its label shows how fast. At 120°F it takes more than 5 minutes to cause a serious burn. At 130°F it takes about 30 seconds. The U.S. Department of Energy's checklist also recommends the 120°F setting, and says it saves energy.

If you can't change the setting, Rheem lists a locked keypad on the electronic model. If the water is hotter than the setting, the thermostat or ECO may have failed. Switch off the breaker and call a technician. Don't wait for it to settle, and keep children away from the hot taps in the meantime. Rheem recommends a mixing valve (ASSE 1017) to cut the temperature at the taps. A licensed plumber installs it.

Breaker keeps tripping

A breaker that trips once after a surge can be reset. One that keeps tripping is protecting you from a fault. The Consumer Product Safety Commission says an appliance that repeatedly blows a fuse or trips a breaker should be taken out of use and repaired or replaced. A hardwired heater can't be unplugged, so leave the breaker off and call a technician.

Noises

Rheem's chart separates the sounds.

• Rumbling: scale or mineral deposits on the heating elements. Rheem says to remove and clean the elements, which is a technician's job.
• Popping or dripping from the relief valve: pressure from thermal expansion in a closed water system. Rheem calls it an unacceptable condition that must be corrected. Contact your water supplier or a plumber, and don't plug the relief valve outlet.
• Rattling while hot water runs: normal for the heat trap fittings, according to Rheem.
• Banging in the pipes when a faucet shuts: water hammer. Rheem says risers or water hammer arrestors can reduce it.
• Hissing or singing that gets louder: the element may need cleaning. Rheem says to call a qualified installer.

Sediment is behind much of the rumbling. Rheem suggests draining a few quarts from the tank each month to clear deposits, and its article says to attach a garden hose to the drain valve and drain several gallons until the water runs clear if the tank hasn't been flushed in over a year. Before draining, turn the power off. The manual warns that the water can be hot enough to scald, so direct it to a drain.

Rotten egg odor

Rheem's manual says water with high sulfate or mineral content, together with the heater's anode rod, can produce hydrogen sulfide, a rotten egg smell in the hot water. It suggests chlorinating the water supply to reduce it. A separate Rheem article says a sulfur-like odor can also point to bacterial growth in warm, stagnant areas of the tank.

Check where the smell is. From the hot tap only points to the heater or the water. In the air, especially near a gas appliance, treat it as gas as described above. For other smells around the house, see our guide to strange smells in the house.

The anode rod is a sacrificial rod that protects the glass-lined tank from corrosion. Rheem says to inspect it annually and replace it when too much of the core wire is exposed. The manual gives the exact limit. Don't remove the rod permanently: Rheem says running without it greatly shortens the life of the tank and ends warranty coverage.

Brown or rusty water

Rheem says discolored water, "especially brown or reddish," often points to corrosion inside the tank. Persistent discoloration usually means the heater is near the end of its life. Check the hot and cold taps separately. If only the hot side is brown, the heater is the likelier source. That's a judgment, not a Rheem statement. If both run brown, the cause is probably the supply, which your water utility can check.

Leaks

Switch off the breaker and close the cold supply valve first. Then find the source. Rheem's guidance says a small amount of condensation on a newly filled tank is normal, and that pooling water around the tank body is serious. Leaks from the bottom often mean corrosion, and Rheem says that requires replacement. Take photos of any leaks, rust or condensation to show a plumber.

Repair or replace

Rheem puts traditional tank heaters at about 8 to 12 years. If repair would cost more than 50% of a new unit's price, Rheem says replacement is almost always the better investment. It also says units over 10 years old are more likely to fail again soon after a repair. Rheem says to consider replacing a heater with a base leak, and one that's had multiple repairs in a short time.

Repair prices vary with the part and where you live, so get a written quote before agreeing. In my judgment, a failed element on a young heater is worth repairing and a leaking tank isn't.

Frequently asked questions

Why is my Rheem electric water heater not getting hot?

Check, in order, the breaker or fuse, the disconnect switch, recent heavy use, the temperature setting and open faucets. Then check the ECO reset on models where Rheem allows it. If none of that helps, the element, thermostat or sensor has probably failed, and Rheem says those repairs belong to a qualified technician.

Where is the reset button on a Rheem electric water heater?

On Rheem's electronic-control model it's the red RESET button on the power board and upper sensor assembly, behind the user interface control and insulation. Turn the power off first. Other Rheem models place it elsewhere, so check the manual for your model before opening any panel.

Is it safe to flush the tank myself?

Rheem includes draining in its care instructions. Turn the power off first and the cold supply off, attach a hose to the drain valve, and send the water to a drain. The water can scald. Never run an electric heater until the tank is completely full again.

How long does a Rheem electric water heater last?

Rheem says traditional tank heaters typically last 8 to 12 years and recommends planning replacement around year 10.

Can I turn the heater down to save energy?

Yes. The U.S. Department of Energy recommends the 120°F warm setting, which saves energy and reduces scald risk. Rheem's own scald chart supports the same setting for homes with children or older adults.

Sources

• Rheem Use and Care Manual for residential electric water heaters (AP21980) (troubleshooting chart, ECO reset, scald chart, draining, anode rod, odor, safety cautions)
• Rheem: 5 Signs Your Water Heater Is Going Bad (discolored water, noises, leaks, sulfur odor, age)
• Rheem: Water Heater Lifespan, When to Repair vs. Replace (8 to 12 years, 50% rule)
• Rheem: What to Do Before Calling a Plumber or Replacing Your Water Heater (breaker off, flushing, leaks)
• U.S. Department of Energy: Home Energy Checklist (120°F setting)
• U.S. Consumer Product Safety Commission: Plug Into Electrical Safety (warm outlets and switches, repeated breaker trips)
• Connecticut PURA: What to do if you smell natural gas (leave, call from outside, no sparks)