Let start by saying that this all started in 2014. I was forced to replace my then 50 year old hot water heater with a new unit after my homeowners insurance refused to renew my policy due to its age. It was a Bradford-White that was installed in the 1960's.
I went down to the local plumbing supply and bought a brand new 50 gallon Bradford White heater,

All was well for about 6 months, then it quit working, the top element was dead and the breaker wouldn't reset on the unit. They told me to call an authorized service center to look at it. I did, it cost me $240 for a house call,
The guy looked at it, said the element and t-stat were bad, and he found a leak at the lower drain into the insulation. He installed a brand new one on the spot. (I had to pay the labor).
All was good again for about two months, then that one died the same way,
Heater #3 got installed...it lasted 8 months, then heater's #4,through #9 all died exactly the same way, at that point the original 6 year warranty was up and they stopped replacing them.
I bought another one, this time from Rheem, and again in about 7 months, the thermostat was again stuck and it blew the internal breaker, Several resets got me the same result, super hot water and a blown breaker.
I finally ripped that one out and took it back for a refund. I had no intention of going through the same thing al over again.
That got replaced with an AO Smith unit, which did th same thing, but that one toasted both elements and blew the breaker in my box on the wall. When they sent someone to check it out they said my water was at fault. That plumber swore by Bradford White and promised I'd have no more trouble with their best heater.
(It looks the same as the one's I had issues with). That one lasted a year, he replaced it at no charge. Now 9 months later, I again have the same issue, the water gets super hot, the internal breaker pops, and it shuts down. The internal thermostat again appears to be stuck on.

I'm on the 14th hw heater since 2014 now and this one is bad again.
Both lines have 122v, the wiring can't be an issue because it worked fine for the first 9 months or so. (each one has).
If I reset the breaker, it almost boils the water before the breaker pops on the unit. I have it set for 145 degrees, and have tried various settings but nothing helped.
The heater is located in a dry basement, elevated off the floor on a 15" tall riser an its plumbed with copper.
The elements and anodes come out looking like new, but a few of the heaters got so hot they discolored the paint.
At this point I'm at a loss, 7 or 8 plumbers couldn't give me an answer, three manufacturers all had the same issue, and the electric and water service in the house are both fairly new. The electric service was redone last fall, the water system was re-plumbed with a new water main and all new supply pipes 8 years ago.

One of the reasons I chose to replace the original heater was that they told me it would save me money every month, what they didn't tell me was that it would cost me thousands in replacements and my electric bill shoots through the roof when the thing gets stuck on for hours on end.

I had a guy tell me the other day at another plumbing supply that the life expectancy of an electric hot water heater is 3-5 years at best, and less in 'certain' instances.

 

Sorry for your problems but this is not something I have heard of before.
I have never seen that many water heaters replaced due to incidental problems.

You're telling us that the upper thermostat is shorting on or is tripping on high heat.
That is not a problem that ever affects new electric water heaters unless there is a defective/shorted element. You could not have possible gotten that many defective elements. Getting 1 or 2 is extremely rare. An internal wiring issue could be possible on the same exact model but you've used different makes and models

Even if you had a voltage problem.... it would never cause a failure. If the voltage was low you'd get minimal hot water but no faults. If the voltage was high.... the thermostats would activate sooner as they are temperature dependent.... not voltage dependent.

A water heater not fully filled with water could could cause problems but not that many times.

Sorry to say.... I have absolutely no idea why you've been thru so many water heaters.
It truly is a first.

 

That really is puzzling. At this point though I am wondering about water quality. Have you had the water tested? Is this municipal water? One thing I'd do is cut the thermostat back to no higher than 130 degrees which might help a little. By the way, electric water heaters do not have an internal circuit breaker. I think you are probably referring to the high temperature limit switch. My experience is that once the limit trips a few times it gets weak and starts tripping prematurely and must be replaced. The best thermostats and high temperature limit switches will be marked T O D for Therm-O-Disc, the manufacturer.

 

Whether its a high temp limit or circuit breaker, it pops after about 2 hours of being reset, at which time the water is near boiling temp regardless of what temp the unit is set at.
I have a box of elements, when the 2nd one acted up, I swapped out the elements but it didn't help. I returned the elements and got two more, plus the plumber who installed the third one tried new elements twice but it didn't fix it. He replaced both the breaker and the stat and it was fine for a few more months but it again started to overheat and pop the interrupt button.
Line voltage is 127 on both sides and we have municipal water here. The upper element comes out looking almost new, the lower element comes out looking like its covered in white powder after it dries off.
It never pops the panel breaker on the wall, the red button on the unit pops out first.
There's a small white plastic screw or knob to set the temp, the lowest marking reads 140. If I go below the last mark below 140 it shuts of completely, other than that it has no effect on the temperature. All settings are hot enough to blister the skin off your hands at the furthest faucet.
The red button pops out and turns off the unit just before the high pressure relief valve begins to vent

 

The problem you describe sounds like a upper thermostat problem. Is it mounted to where it makes a good contact with the metal surface of the tank? Contact with the tank is critical as this is how it senses temperature. I don't think I have ever seen a thermostat with 140 as the lowest setting, what brand is it? Years ago electric water heaters came from the factory set at the factory to about 140, but most people I knew wanted them set down, the water was just too hot. Here's one with the lowest setting being 90 degrees. The circuit breaker never trips because it isn't overloaded.
https://www.homedepot.com/p/Everbilt...834379#overlay

 

You need to measure for 240v. Nothing runs on 120v.

It doesn't make a difference if you have higher than normal voltage.... the thermostats will still operate to keep the water at the set temperature. A few volts higher will heat slightly quicker.

You DO NOT have a thermostat problem.
The top thermostat is tripping on high heat because the water is too hot.

What you need to do if you want to diagnose the problem..... turn off the power.
Remove the wiring from the top and bottom elements.
Using a meter with a high resistance setting..... measure from all four element terminals to ground.
If any show any continuity... that element is bad.

A leaky element will keep heating even if its thermostat is shut off as only one half of the circuit is opened.

 

The elements show no continuity to ground.
The elements have 247 volts to them tested with a Fluke meter.
The used elements show 12.5 ohms, the new one's showed the same resistance across the terminals.
Both elements are now new, but the problem persists.

The whole connection panel is just clipped into place, it moves around quite a bit under a spring type retainer.
The replacement panel doesn't have temps marked on it, it just says HOT, A, B, C, & HOTTER. Its set to the lowest setting. The upper part with the red button is separate from the bottom, the top half has a shiny bare metal element on the back that contacts a bare patch on the tank. It touches it but isn't a 'tight' connection.
The lower portion rests on a steel bracket and sort of slides into it. there is no direct contact with the tank on the back side.
Regardless, changing both elements and the control panel made no difference.
The water is so hot it burns your hands and it pops the red button after about 6 hours or so.
The original unit had a small label under the dial that read 140 on the low end, then 'normal', then 'Hottest'. Other than the markings it was identical to the new one.
There is always full 247 volts to both elements, the only time it shuts off is when the red button pops out.
The temp dial does nothing but its hard to tell if the water is actually hotter since its already nearly boiling the water.

I have no doubt the red button pops due to it getting too hot, if it didn't pop the button and kill the power the thing would have blown to bits sooner or later.

I had a conversation with a couple of neighbors here and both said they replace their water heater every couple years, "They don't last that long" is what their plumbers told them.

I don't like the water being so hot, and this has been running up my electric bill as well. It seems that when I install a brand new unit, its fine for a few weeks or months, but there's just not that much here to go wrong.
Just two elements and a panel, attached to a tank.



Just above top heating element



Top element always comes out clean
Bottom element is always white and powdery
Both test fine though, I replaced both simply because they were out in an effort to get to the bottom of this issue.
Both elements pictured were new in Aug.

 

I should also note that if I turn the white knob down below 'Hot', the heater shuts off completely.
Higher settings have no effect, so its not a 'bad spot' in the thermostat control.

 

This may be a dumb question but how does the thermostat read the temp?
Only the upper part that holds the red button has a cutout in the insulation where it contacts the tank directly.
The thermostats sit on brackets up off the tank, seemingly insulated from the actual tank.
There's a round metal area behind the red button that is pressed against the tank when its clipped into place. It looks like a round bit of shiny metal about the size of a nickle or so.
releasing the top clip lets the whole assembly lift out of the bracket below.

Its popping the red button out even faster now with the two new elements and new thermostats, it takes only about 2 hours now for it to overheat.

A plumber/neighbor told me to just buy a new water heater and to stop messing with this one. I've done that a dozen times now and every one ends up the same way with the exact same problem after less than a year each time.

 

Did you really have nine water heaters each spring a leak somewhere in their tanks in less than a year for each? You must have really corrosive or otherwise chemically active water. (Also a higher selected temperature will accelerate corrosion, thus "home" water heaters are not warranted for commercial use.) You might want to have a lab do an analysis for unusual chemical content or concentration. If an element corroded excessively before the tank did then you noticed that the element burned out.


Do you go / have you gone on vacation more than 2 weeks and coming back home you find a hot faucet gushing "air" for a long time before the water starts coming out? Water heaters not used for a long time may build up hydrogen gas inside and when so much accumulates to displace water (back out the water meter to the public water main) the top element becomes exposed and burns out.

Also try this: Drain some sediment from the tank by following all of the steps below.

1. Get a garden hose spigot cap. One usually comes with a daisy chainable lawn sprinkler.

2. Turn off both the water heater circuit breaker and the water heater shutoff usually on the wall near the heater.

3. Drain a whole gallon of water out of the water heater drain valve down below. More if the container you use to catch the water is bigger.

4. (Close the drain valve and) shut off the cold water supply.

5. Open a cold faucet upstairs.

6. Drain another gallon or more out of the water heater drain valve.

7. Turn the cold water supply back on.

8. Open a hot faucet upstairs and watch a steady stream of water gush out fast for 60 seconds.

9. If you noticed sediment in either of the two bucketfuls, repeat all steps 1-8 above, in order.

10. Turn the water heater power back on.

 

There's your problem. In Post #5 I said:
The thermostats MUST sit directly on the steel tank surface to sense the water temperature in the tank.

 

On all of these, only the upper safety switch touches the tank itself. The two t-stats are sitting on shiny brackets that put the stat about 1/8" off the tank.



I reset it two days ago and so far its been working as it should but I'm not confident.
Its done this before only to stick on again and trip the red button.

If the T-stat is supposed to touch the tank, they went out of their way to make sure it doesn't.
There's a plastic insulator stapled to the fiberglass insulation stuffed behind the two T stats, there's a cut out in the batting and plastic where the back of the over temp switch can touch the tank.
There's a spring clip that grabs the top lip of the overtemp switch to hold it in place.
The lower stat fits into the bracket.

 

Here is the top thermostat I'd use, it does sit directly on the surface of the steel tank.
https://www.homedepot.com/p/Everbilt...834379#overlay

 

The only way the thermostat can sit on the tank is if the bracket that holds it in place is cut off. The bracket is substantial and holds the body of the unit about 3/4" off the tank surface, they even put insulation behind it.
I suppose the bracket itself can transfer heat to the stat but I can't say how much. Its never very warm to the touch, even if the water is near boiling out of the faucet.

Regardless, for what ever reason, its been working fine now all week.
I did change the both t-stats and both elements but it changed nothing at the time. Then all of a sudden it started working fine again???
Its done that before, over last summer, with the last water heater, it would go a week or two just fine, then need to be reset over and over again, then be fine again for a while. Its been a pattern with every one of these water heaters for years.
changing parts, or replacing heaters doesn't seem to solve the problem, at least not for long term.