Q: While I don’t oppose bringing in a plumber for a service call, I would like to know how I can test the electric heating elements on my water tank. Can you tell me how to do that? Are any special tools necessary to accomplish this task? - Mark C., Spokane
A: To start the troubleshooting process, first check the hot water at a faucet to determine which element is not working. If the water is cold, then the top element needs replacing. If you get a small amount of very hot water followed by cold water, then the bottom element needs replacing.
If you have no hot water at all, it’s possible that either the breaker or the high-limit switch on the upper thermostat has tripped. If the water gets too hot, the upper thermostat shuts off, cutting power to both upper and lower elements. To reset, remove the water heater access panel and push in on the red button. This normally indicates that something else has gone wrong with the water heater, for example, one of the thermostats has a problem, a thermostat is not firmly pushed up against the tank, or an element is shorting out.
In most cases, though, the lower thermostat gets stuck in the closed position, causing the water temperature to rise to a point that the upper thermostat shuts down. When this happens, the thermostat is compromised. Thermostats can be tested, but for what thermostats cost, it will be less expensive to replace them both than to test them in their own environment (you would need to remove them in order to do a proper test).
You can test the heating elements for continuity using a multimeter, an extremely handy tool to have in your toolbox. Multimeters come in two different styles and price ranges: digital and analog. A digital model displays the readings in numbers while the analog indicates values with a needle over a scale.
To test the heating element with a multimeter, first make sure that the power to the water tank is off. Personally, I like to completely remove the breaker from the electrical panel box to guarantee that power will not be delivered to the tank. However, now that I’ve said that, you still need to check power at the tank because it’s possible that the wrong breaker was flipped or the breaker was mislabeled.
To check the power, remove the water heater access panel. Set the multimeter to AC and, depending on the unit, you could have removable black and red test wires with probes on one end. Stop at this point and read the owner’s manual to make sure that the other ends of the wires are plugged into the proper input jacks on the multimeter so you don’t damage the unit. When you are comfortable that the multimeter is correctly set up for voltage reading, then take the black and red test probes and place each one on the top pair of terminal screws on the upper thermostat to check that current indeed has been turned off.
To test the elements, remove one of the wires from the terminal screws located on the face of each element (a false reading will occur if one of the wires is not removed). Set the multimeter to the OHM U position (refer to your owner’s manual for the proper step), then touch the black and red probes, one to each terminal and starting with the upper element first. If you get a reading of 7.5 U and greater or the needle points all the way to the right, the element is closed and doesn’t need replacing. Do the same for the bottom element. If you see “Infinity,” “OL,” or “1” on the digital or the needle is all the way to the left, then it means the element is open and needs replacing.
Here’s another suggestion: 95 percent of all water tanks carry a 6-year unlimited warranty which covers thermostats and elements. This means that within the first year the manufacturer of the tank will pay for parts and labor. In the next five years you only have to pay for labor as the manufacturer will pay for the parts. If the tank is within the warranty period, it would make sense to contact the manufacturer through their toll-free number (possibly found on the side of the tank or in the owner’s manual) and let them send out a service tech to take care of the problem.
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