Water too hot: electric water heater troubleshooting video

Tools and parts needed

• Multimeter

• Hand tools

• Work gloves

• Heating element

• Thermostat

Causes of overheating

Hi, this is Wayne with Sears PartsDirect. Today we're going to talk about an electric water heater that's overheating.

Nobody expects their tap water to be scalding hot. For safety’s sake, your tap water should never be hotter than 120 degrees F. But that's what can happen if your water heater has a shorted heating element or a broken thermostat.

A thermostat that's stuck in the "on" position will cause the heating element to stay on constantly, overheating the water in the tank. Or, if the element breaks, it can make contact with metal inside the water heater, creating a short circuit. Electric current flows through the element to the metal, causing the element to heat constantly.

How to check for a short circuit

We’ll want to check for a short circuit first because it creates a dangerous electrical shock hazard.

If you suspect that you have a shorted heating element, do not touch the cabinet until you have turned off the circuit breakers. Do not turn the circuit breakers back on until after you have repaired the heating element or the wiring.

We’ll use a multimeter to check the elements for a short to the metal cabinet. 

With the house circuit breakers shut off, remove the cover on the lower heating element. Pull the insulation and plastic cover up to access the heating element leads. Set your multimeter to measure resistance.

Touch a meter probe to one of the leads on the element and put the other meter probe on the bare metal frame next to the element. You should see a 1 the far left corner of the meter display indicating no continuity.

No continuity means that there is no current flowing to the metal cabinet. If you measure any resistance between the element lead and the metal cabinet, then the element is shorted and needs to be replaced.

Be sure to check both sides of the heating element.

If you don't measure continuity from the element to the cabinet, check the resistance through the element to see if it's okay. Touch one meter probe to each of the element leads. A good heating element will measure about 13 ohms of resistance.

If you do measure 13 ohms of resistance through the element and no continuity to the metal cabinet, then you know that the heating element is okay.

If you measure no continuity through the element, drain the tank and replace the element. This video will walk you through that process.

Check the upper heating element for a short to the metal cabinet in the same manner. Replace the upper heating element if it's broken and/or shorting to the metal cabinet.

How to replace the thermostat

If you don’t find a problem with the heating elements, then you know a broken thermostat is what’s causing the water to overheat.

So which one do you replace? Unfortunately, there is no way to test the thermostats to see if they're turning off the elements when they’re supposed to.

You can try replacing the lower thermostat and see if that resolves your overheating problem. If not, you’ll need to replace the upper thermostat as well. This video will walk you through replacing a thermostat.

Well, I hope this video helped you out today. Check out our other videos on the YouTube channel and if you like them, subscribe.