Plumbing

Testing Water Heater Voltage

Name: Testing Water Heater Voltage
Uploaded: 2025-10-01T14:46:35Z
Duration: 2 min 42 s
Description: Learn how to safely test a water heater with a multimeter. Always use one hand when possible to avoid risk, and set the meter to AC voltage. Check the top thermostat first—when it clicks, the element energizes at 230–240V. Then confirm the bottom thermostat cycles correctly. Proper testing ensures both elements heat in sequence and that the system reaches the correct set temperature.

Learn how to safely test a water heater with a multimeter. Always use one hand when possible to avoid risk, and set the meter to AC voltage. Check the top thermostat first—when it clicks, the element energizes at 230–240V. Then confirm the bottom thermostat cycles correctly. Proper testing ensures both elements heat in sequence and that the system reaches the correct set temperature.

Electric Water Heater

Diagnostic

Electrical

Mark Cukro

How did you like this video?

Very Good

Good

Not Good

Transcript

Okay, so we're gonna use a multimeter. A few things before we do. Any brand meter will work. However, there are tips, usually particular brands that people prefer. We're gonna put this on alternating voltage. I have two leads in one hand, I wanna make sure that I can read the display, and if you're measuring live voltage.

Do not have one lead in each hand. If there's no power, you can put one lead in each hand. So the best practice is to use one hand. Sometimes you can get an alligator clip and I'll show you what I mean. You can have two hands, one on something that's non-conductive, but what you really want to avoid is having one lead in each hand as much as possible.

Sometimes you have no choice, but try if you can. So let's take a look up close. Okay, so now. I don't hear any noise outta the elements, so I'm gonna put one lead on, one screw terminal, and one lead on the other. Now I should get around 230 to 240 volts, and right now, put this back in here. There's no power, which means that the thermostats not calling

for energy. So I'll turn this up and you hear a click. Now let's take a look at the meter and you can see that we have 240 volts. And if you listen, you can hear a noise. And that noise is the sound of the element being energized. As a technician, you should wait to see if it runs works. And now I'm gonna turn the thermostat back down.

You hear the click and now the element is off. So now you know. That the thermostat is operating manually and we don't know about the temperature yet. I'll do the same for the bottom thermostat, but now there should be no voltage here. And then when I turn on the bottom one, that should be energized. If you take a look at the whole water heater when you call for hot water, the top element comes on first.

Then the bottom element comes on. So this will heat and fill water in the tank until about right here. Then this thermostat will get satisfied. This one will cycle on and then it will go to the temperature. So the mechanical functions are perfect, but what we have to wait for now is that it actually reaches the desired temperature, which is why it's so important that you take.

Temperature readings and make sure both of the thermostats are set at the same temperature.