If you’re familiar with the thermostat controls on your water heater, you may have noticed that 120 degrees Fahrenheit is the recommended setting. That’s considered the sweet spot because it’s hot enough to prevent the growth of harmful bacteria, but not so hot as to pose a serious scalding hazard.
There are a few types of problems that can cause your water heater to overheat the water in the tank, and when that happens, the emergency cut off (ECO) kicks in to shut down the appliance completely. To reset it, you’ll need to press the red reset button on the ECO, which is usually attached to the upper thermostat.
When a water heater starts tripping the ECO repeatedly, it’s time to call a plumber for service. There’s a good chance that the water in the tank is dangerously hot, and since the problem is usually caused by a failed component, it won’t get better until the bad part is identified and replaced.
Here’s a quick rundown of the most likely causes:
Your Thermostat is Bad
Or perhaps both of them are -- your water heater has two thermostats, one at the bottom of the tank and one at the top. Each thermostat controls a heating element, which heats the water. When the water reaches the desired temperature, it’s the job of the thermostat to shut the heating element off. But if one or both thermostats go bad, it can force the heating element to run continuously, overheating the water.
Your Heating Element is Bad
Heating elements can also go kaput with age. In many cases, they’ll just stop heating altogether -- but sometimes a heating element can develop an electrical short that causes it to receive power even after the thermostat shuts it down. This produces the same result: overheated water and repeated tripping of the ECO.
Your ECO is Bad
The ECO itself is yet another part that is susceptible to failure. This could be due to wear and tear from repeated instances of overheating, or it could just be spontaneous failure. A fried ECO switch will need to be replaced, but on the bright side, this problem alone can’t overheat your water.
If your thermostats, heating elements and ECO are all operating properly, it’s possible that a loose wiring connection could be producing another source of heat inside your water heater. In addition to causing your ECO to trip repeatedly, this problem also poses a serious risk of fire or electrical shock. Leave it to a trained service professional to determine if your water heater is suffering from wiring problems.