Water heater blew thermal fuse on thermostat -- no hot water

[westerberg19390]

Problem started when we noticed tap water was extremely hot. Shortly after we stopped getting hot water. I removed the cover of upper access panel and noticed that the upper thermostat's thermal fuse had been tripped. Removing cover of lower access panel showed the coating had melted on the wire connecting the thermostat to the heating element. Is the solution simply a matter of replacing the lower thermostat, or is there a deeper problem ?

 

[sarg]

Just some thoughts to ponder.
How old is the heater ? If over a decade replacement might be the best solution.
If the unit is in good shape then replacing the elements and the thermostats while you have it apart is wise. A kit with both thermostats & elements is around $40.
While the bottom element is out use a wet vac with a length of pliable (auto) hose to clean out the sediment. Check the anode rod through the same element hole. Replace the wire that is damaged.
I do the above twice per year to avoid issues. When installing a new unit I replace the drain valve at the bottom to a 3/4 ball valve designed for flushing the tank. It is also a good idea to break free the anode and reinstall as they are installed very tight from the factory . The factory compression valves do not pass sediment and are slow to drain.

 

[havasu]

My vacation house has a 40 gallon electric water heater. I bought all the stuff necessary to change out the drain spigot, but it looks like they used epoxy on the threads, and used a plastic pipe coming out of the heater. I have applied so much torque trying to remove it, but gave up fearing I would snap the pipe off.

 

[Twowaxhack]

Well there are several possibilities.

The easiest thing for me to tell you would be :
Check the wiring connection to the water heater itself.
Replace any burnt wire
Replace your thermostats
Replace that lower element, I’d probably do both.
Make sure all wire connections are tight.

Then check your voltage.
Check the amperage draw of the elements
Check the operation of the thermostats.

Check the final temp of the water and make sure it reflects the set point of the thermostats.

You could also check the hot system to make sure there are no leaks.

That’s probably what I’d do if I came to your house.

 

[Twowaxhack]

I’d probably also check your water pressure and thermal expansion tank or control method. But maybe not Is it lunch ?

 

[TomFOhio]

You didn't say how old the tank was. If under 6 years old you can probably get parts from the company. You might
even be better off to replace it if your not comfortable replacing all the parts and having it be safe.

 

[westerberg19390]

Water heater is an AO Smith model I got from Lowes 4 - 5 years ago. Both heating elements are good per a multimeter continuity test. The lower thermostat was fried even to the naked eye, so I replaced it with a new one. Everything is working fine so far. I'll keep an eye on it. Thanks for replies.