Electric water heater - repalced everything still no hot water

Hi everyone. I hope someone can helo me with this as I am baffled beyond imagination here. I have an electric hot water heater that burned out the bottom element. I opted to replace both elements and thermostats since this was an in-expensive investment.
So replaced both upper and lower elements, upper and lower thermostats..and still no hot water.
one thing I did do is buy another set of elements and when I removed the first set, I noticed that only the edges were getting hot and not the entire element..could it be the I need to adjust the thermostat to a higher temp?
Also, I checked all electrical wiring and I have voltage everywhere its suppse to be.. Also did a resistance test on all 4 elements, first set and second, and all pass with flying colors..
So I am confused and not sure where to look next...
This is a 240 volt system and both leads are hot..checked and verified.
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the element and the element resistance is correct, there is no way it will fail to heat.
When you say both 240 volt leads are hot, do you mean they have 240 volts between them or that each has 120 volts to the neutral or ground? If the latter, and the leads are connected to the heater, you can have one fuse or breaker open.
With everything connected normally, test for 240 volts across the input leads. If present, test for 240 volts across the element terminals. Do not confuse yourself by making any measurements to neutral or ground.
If you have 240 volts at the input but not at the elements, one of the thermostats is open or something is miswired. Most dual element heaters only operate one element at the time. From cold, the upper element heats until the upper thermostat gets hot enough to switch. The upper element then turns off and the lower element is switched on, both actions done by the upper thermostat. The bottom thermostat will still be cool and its contacts will be closed. When the bottom element heats the water hot enough for the lower thermostat to switch, it will turn off the bottom element.
Most of the heating is then done by the lower element, the upper element only coming on when the top of the heater gets cooled down by using a lot of hot water. It will help to understand this to know that the cold water goes thru an internal "dip tube" and actually enters the heater at the bottom.
Your big mistake was in replacing the upper element and the thermostats unnecessarily, but you should be able to get it going again if you understand how it is supposed to work.
Don Young
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Mark wrote:

Maybe the "dip tube" that is on the inlet side is broken or corroded away, if that happens then the cold water comes in the top and goes right back out the top without heating. Check to see if you have hot water at the bottom of the tank by opening the drain valve.
George
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I'm with Don on this one. If you have 240V measured across the heating element and the heating element is good per resistance check, then it has to heat. At least at that point in time. Keep in mind some heaters are on a timer system controlled by the electric meter, where power is only provided off peak at a reduced rate.
I also agree with the advice that it was a mistake to replace the working element and 2 thermostats. In my experience, the element failure doesn't appear to depend much on length of service. And I've never had a thermostat go.
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The lower thermostat on mine stuck with the contacts closed. It kept heating until the safety overheat breaker popped. I had to reset it after I changed the thermostat. But I knew it had to be reset because I had no voltage on either element. I am also mystified by the OP posting.

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