Troubleshooting An Electric Water Heater
In this video, you will learn how to easily diagnose a problem with your electric hot water heater. This particular hot water heater is an 80 gallon dual element.
As you can see, I have both covers removed, the upper and the lower. The upper and lower both consist of a thermostat right above each element. Now, there’s the upper element just above that you’ll see the thermostat dial.
How this works is very simple. The first thing we are going to do is make sure you have 240 volts entering the hot water here because if you don’t then the rest of this testing is going to be a waste.
You are going to go at the top of your electric water heater, which is right there. The first thing you want to do is remove the cover and expose the power wires entering the hot water heater. You’re going to take your probe and you’re going to reach them into the wire knots.
Hi, in this case, I’m going to set the meter for 250 volts, the needle should swing all the way passed the end. If you have a digital multimeter, you’ll get a reader. I’m going to take one probe, shove it into one of the wire knots to get it touch it to there. You see the needle swung over. This you’ll know you have full 240 – 250 volts entering the hot water heater. You can rule out power as being a problem.
Now we’re going to move on to the next step. First thing you want to do is you want to turn off the power at the main breaker. Once you established that there’s power entering the heater. Let’s go over to your breaker, usually a double 30 or double 20. Shut it down, confirm that it is off by going two wire knots on top of the water heater first.
Now, once you turn off the circuit breaker you want to take your digital multimeter on the same 250 volts setting or higher. Then you’re going to want to take each probe, you’re going to touch one to that screw and one to that screw to verify power is off.
The next step is to make sure this reset switch is not faulty. You’re going to want to test and how the switch works, current flows in on one leg at this screw and one leg at this screw. When the switch is working properly, the power will flow from this screw down to that one and this screw to that one.
We’re going to do now, I’m going to have this held up some tapes so I can do with all my hand here. Make sure your digital multimeter set to a low Ohms range.
And we’re going to watch to make sure that the needle swings to the right when I go between the top right screw and that screw. That will verify that the circuit is close allowing current to flow pass the reset switch into the thermostat.
I touch one there and one there and you see the meter moved. She swung to the right so you know that is good. You’re going to do the same now on this two sets of screws. One there and you know that’s good. You know current is flowing through the reset so you can rule out the reset.
Once you’ve established that the high temperature reset switch is not faulty. The next step is to check the thermostat and how that’s done is very simple. You have a 120-volt leg feeding through the high temperature reset into the thermostat.
Now to test the thermostat, you’re going to want to rotate the temperature to the highest setting first. You could hear it just click. Sometimes they click but they don’t trigger so it’s good to check them. Put one probe on that screw and one on the yellow, you can see the meter swing indicate current is flowing to the heating element the water to heat.
Now you’re going to rotate the temperature back to the coolest setting and make sure it’s clicked off. The needle should not move and you’re good to go. You just confirmed your thermostat is working properly.
The next step is to check heating element to make sure that’s working properly. To do that, you’re going to remove all screws, remove all screws. Now that the wires have removed from the screw terminal, you’re going to set your meter to the lowest range which is a x10.
For this test, ideally you should use a digital multimeter on the lowest range. What you should get is a very low resistance reading. If it comes out zero, that means it’s a short, which you don’t want.
If it comes out very high, that’s a problem also. As you can see, there’s continuity between this terminal and that terminal indicating is a very low resistance reading, indicating there’s a very low resistance between this screw and that screw, which is the heating element.
The next test is going to be, set this to the highest range you have. In my case, it’s a x1000. You’re going to check from each screw to the tank body itself. You should see no movement on the needle. Go with the other screw, same thing.
If this moves when you go from the steel tank to one of this terminals, that would indicate a severely corroded heating element. What’s happening is the current is flowing outside of the heating element into the water and grounding on the tank and that’s not good.
After the testing procedures is complete, on the upper portion of the water heater, you’re going to repeat the process on the lower. You will do the same test on the lower part of the heater, 120-volt leg fitting into the top of the thermostat.
When the thermostat triggers it allows current to flow across the terminals into the heating element. This is the return leg heading back so you get your full 240 and to test this is the same way.
You’re going to turn the dial all the way counterclockwise and check for the continuity. Then turn it clockwise fully and make sure you get no continuity. One direction continuity and the other direction no continuity. After this test are completed you should know exactly what the problem is with your water heater.