[zeustogo]

Breaker to electric water heater was tripped. I reset it and about 6 hours later water was scolding hot. I have turned breaker off. Was working fine before, nobody has changed anything. What are some possibilities?

[massplumber2008]

Hi Zeustogo

Most likely the upper thermostat has gone bad...usually trips at the red rest button at the thermostat itself (under access panel). These are super cheap and easy to replace, so I would start there...

Mark

[speedball1]

I agree with Mark, Sounds like the thermostat is kicking on both elements at the same time. Elements pull 19 amps, with both on they pull 38 amps on a 30 amp breaker. The breaker should have opened up instead of over overheating the water so I would replace both the thermostat and the breaker. Good luck, Tom

[zeustogo]

It still over heats. I replaced the upper thermostat. I had 240 volts to top element for about a half an hour and 0 volts across the bottom element. Than the top element had 0 volts across it and the bottom element had 240 volts.After about a half hour the water tank temp. at the bottom was 110 degrees. Both thermostats were set at 125 degrees. I wanted to leave the house so I turned the bottom thermostat towards 90 degrees to make sure it would shut off. It clicked and I still had 120 volts across the bottom element. I don't know if that is normal. I put my amp meter on one of the wires going to the bottom element and it was 0 amps so I figure it is OK. The top element at this time read 0 volts. I turned off the breaker and readjusted the bottom thermostat to 125 and the water heater back together and turned the breaker back on which happens to only be a 20 amp breaker which is probably why it tripped earlier. About 4 hours later I checked my hot water it was scolding. I turned off the breaker removed the covers made sure I didn't have voltage checked for continuity through reset button and it was opened. I measured the temp. of the water tank and both top and bottom were 168 degrees. I took off the bottom thermostat took both thermostat to work with me and used a heat gun to see if they would open at the right temp. Both seem to work fine trying them at different temps. Any more ideas on what to do next? I forgot I also checked the bottom element to ground one side did have continuity to the tank but I still had the wires on the terminals, that probably wasn't a good test.

[speedball1]

Recheck the thermostat wiring and replace the breaker with a 30 amp breaker. Good luck, Tom

[zeustogo]

Thank you Mark and Tom for trying to help me. I took a picture of the wiring before I removed the old thermostat and put it back exactly the same verifying it with the picture I took. That is how it was wired for the past quite a few years with out any problems. I will change the breaker as soon as I can. Here is some more information, The heating elements are 3500 watts and the label on the outside of the tank refers to 4500 watt elements. If anyone can think of something else that can cause the water to get so hot let me know. When I get a chance at home I will monitor the water heater to see if a thermostat stays closed when it should be open or if anything else unusuall is happening. I will post what I find out when if finally starts working right.

[massplumber2008]

Zeustogo

This issue is almost always related to the upper thermostat, but it could also be the lower thermostat or even the elements, so these can be tricky, for sure!

As suggested, change over to a 30 AMP double pole breaker, and then check the elements for continuity (remove wires from each element and take reading)...more accurate in my opinion compared to an OHMS test. Finally, even though you have tested the lower thermostat and it appears to work, I would change that out as it only costs another $11.00, right??

Since nothing else has changed, it can only be these things, so take a step at a time, and you'll get 'er fixed up!!

[hkstroud]

It clicked and I still had 120 volts across the bottom element. I don't know if that is normal.

Assuming you mean 120V to ground that would be correct.

I forgot I also checked the bottom element to ground but I still had the wires on the terminals, that probably wasn't a good test.

That is correct, one side of the circuit is always connected to the heating elements. The thermostats interrupts the other side. Therefore, you always have 120V to ground to each heating element.

one side did have continuity to the tank

Please explain that part of your statement. Hopefully you mean you did a voltage check between the element terminal and the tank. If you did a continuity check and show continuity between the element and the tank you have electrical short between the element and the tank.
The red button is an over temperature sensor, not an electrical circuit breaker. Your wiring should 10-2 wiring and the breaker should be 30 amps.

I agree with Mark, must be a faulty lower thermostat.

[zeustogo]

I have fixed it temporarily. I removed the wires from the elements. I had 12.7 ohms across the top element and OL across the bottom element I also had some resistance from each bottom element screw to the tank. When I get time I am going to replace both elements. For now I removed the wires going to the bottom thermostat and bottom element and turned it back on so I have some hot water. Now it is heating to 125 degrees instead of 168 degrees. The top thermostat reset button did trip after I replaced it and it had got up to 168 degrees before I had discovered the problem with the bottom element. When I replace the bottom element I will let you know what it looks like. I anticipate it has a hole in it. The 20 amp breaker is due to the wiring being 12/2. The water heater is 22 years old and the house is 50 years old. I will probably leave the 20 amp breaker in unless it trips under normal usage.

[speedball1]

Check it out!

[massplumber2008]

Hi Zeustogo

Thanks for taking the time to update us...always appreciated. The 20 amp 12/2 still bothers me and I'm pretty sure it would bug your insurance company should something happen here, so please do consider updating as soon as you change out that old water heater (or as soon as you can)!!

Thanks again!

Mark

[speedball1]

Let me make it a bit clearer. Your element pulls 19 amps, you only have a 20 and that isn't big enough. Replace with a 30 amp double pole breaker ASAP. Good luck, Tom