Water Heater Update

Came home from work today and the T&P valve on the tank is still dripping even though the tank is full of cold water and the power is off.
So obviously the T&P valve is toast.
I will replace it.

Also noticed the hose on the drain valve is dripping.
I had flushed some water out the tank with it yesterday.
It obviously will not turn all the way off now.
I will replace that also.

Took the wires off the heating elements and thermostats.
Checked the heating elements with an ohm meter.
Have continuity between the two screws.
Have no continuity between the screws and the heater case.
So the heating elements seem to be good from the info I have been able to find.
The thermostats also check out but I assumed they would since the tank is full of cold water.

So now I believe one of the thermostats is bad as in will not cut off.
I still believe something caused the water to heat above 210 degrees tripping the T&P valve.
Since the heating elements check out and are not shorted to ground I have to turn my attention to the thermostats.

So my game plan now is to replace the T&P and drain valve to stop the leaks.
Then I will turn it on and bring it up to temperature.
Once up to temperature I can check the thermostats again with an ohm meter and see if one of them is not cutting off.
With work it might be Saturday before I get to this.
I can live without hot water for a few days but do not want to have to go without water in case I run into a problem.

Thanks for your help and ideas so far.
It has been very helpful.

It sounds like you did some good troubleshooting, before you buy parts, as it should be done!

Thanks for the update. A bad thermostat seems likely.

In case you don't know the sequence, here's how the two thermostats work: When the heater is stone cold, only the top element is on. Once the top thermostat gets to its set point, it shuts off the top element and supplies power to the lower thermostat. The lower element then comes on until the bottom thermostat gets to its set point and shuts off the bottom element.

Once all the water in the tank is up to temperature, only the bottom element operates, unless enough water is drawn from the tank to cool the top thermostat below its set point. When that happens (say you run a load of laundry followed by a long shower), the sequence above starts over.

Both thermostats should be set to about the same temperature, by the way.

I agree.

Get a price for all of the components that need replaced, and compare that to the price of a new water heater.

Before the relief valve opens, you have a high limit switch above the top thermostat. It should have opened, turning off the power.
So in my opinion, one thermostat stuck closed(on) and the high temp limit switch(the red reset button) didn't do its job. Then the relief valve did its job.

Replace thermostats and high limit switch.

If no hot water, replace heating elements..

I think you should convert it back to burn distillate fuel They are the newest sensqation. LOL

reminder,, the top thermostat has priority.. so when cold as it is now... the power will only be fed to the top element. when that portion is up to temp, the the top thermostat will allow power to go to the bottom thermostat. In normal use the hot water rises up, and cold water is fed into the bottom... so normal use water is drain off the top, and the bottom thermostat will come on first as it senses the cold water... If you use too much water and cold water gets to the top, the top element will kick in and the top stat will feed it first as to try to keep up where the water is leaving. So be aware of that... The tp valve... you you keep tripping it, you can sometimes get lucky and flush out the piece of lime in it and it will stop dripping. crap shoot? The build of of lime is why I am reluctant to test them, because its a bugger to get them clean enough to reseal correctly... AND its usually the same for the bottom drain... so much gritting lime in it that it will not shut off... I have had to buy a hose bib cap in some cases to seal off the drain valve because I could not get the drip to stop. Hope none of this is redundant.