Why is my water heater making the water so hot?

It is possible the element is grounding, but don't think for a second your lower t'stat hasn't failed. Just because it is new, doesn't mean it didn't already fail, especially with a grounded element.

This site may help you.http://waterheatertimer.org/How-to-troubleshoot-el...

by way of fact which you're drawing off warm water speedier than it is heated, or the heater isn't suitable for a shower. try turning the nice and comfortable water down somewhat to be certain if it improves.

First, you get today's prize for accuracy for calling it a "water heater" instead of the dumb@zz term "hot water heater." Now for the problem. I believe you have a defective lower element that is partially grounded out, making it heat continuously. The thermostat is single pole, so voltage from the unswitched leg is always on. A grounded element will heat even if the thermostat is open.

We get silt in ours because our water comes directly from a spring, I've noticed lately the water will be hot, hot, and then normal. We need to clean the silt out of the bottom of the heater for it to work correctly.

you have a heating element out,

usually the top one goes first