Most residential electric tank heaters have an upper and a lower heating element, each controlled by its own thermostat behind a cover panel on the side of the tank. The upper element heats first. Once the top of the tank is hot, control passes to the lower element. A high-limit switch, usually with a red reset button near the upper thermostat, cuts power if the water gets too hot.
That sequence explains the common symptoms. No hot water at all often means no power, a tripped high-limit or a failed upper element. A small amount of hot water that runs out fast often points to the lower element or its thermostat.
Symptom to likely cause
| Symptom | Likely cause |
|---|---|
| No hot water, breaker tripped | Shorted element or a wiring fault |
| No hot water, breaker on | High-limit tripped, or a failed upper element or thermostat |
| Some hot water, runs out quickly | Failed lower element or thermostat, or sediment burying the lower element |
| Water far too hot | Stuck thermostat; high-limit may trip repeatedly |
| Takes much longer to heat | One element failed, or heavy sediment |
What an owner can safely do
- Check the breaker.Look for a tripped double-pole breaker for the heater. Reset it once. If it trips again, leave it off.
- Look for leaks.Water at the access panels or under the tank changes the situation, so shut off the water and power.
- Note the pattern.No heat, little heat, or overheating each point a plumber toward different parts.
- Don't power an empty tank.If the tank was drained, it must be completely full before power is restored, or the elements can burn out.
Repair cost drivers
- Parts
- Element, thermostat or high-limit, depending on what failed
- Draining
- Replacing an element usually means draining at least part of the tank
- Sediment
- A buried lower element may call for a flush as well
- Tank condition
- A corroded tank may not be worth new parts
Ask the plumber
- Which element or thermostat failed, and how did you test it?
- Was the high-limit tripping because of a thermostat fault?
- Is there enough sediment to justify a flush?
- Is the tank in good enough shape to keep repairing?
Common questions
Can I press the red reset button myself?
That button sits behind a cover over live wiring, and it usually tripped for a reason, such as a stuck thermostat. Have the cause diagnosed rather than resetting it repeatedly.
Why did the element fail?
Elements wear out, and sediment from hard water can cause the lower one to overheat. Running an element without water around it also burns it out quickly.
Is it worth replacing elements on an old tank?
If the tank is sound, parts are a reasonable repair. If it shows rust, leaks or rusty hot water, weigh replacement instead.
General information for Orange, not a quote or professional advice. In an emergency, call 911.