Electric hot water heaer element buied in sediment?

We have an 80 gallon AO Smith electric HW heater of an unknown age (bought house 3 years ago). Probably at least 10-15 years old (label on it says "Conservationist"). Water source is a well.
We suddenly had no hot water. After removing element access panels, I see that the wire to the lower element has literally burned off of the thermostat block at the screw. Although the circuit breaker (30 amp) did not trip (nor did the reset button on the thermostat for the upper element), I see signs of high current draw: the plastic "cover" is melted; the insulation on the detached wire crumbles when touched or wire is bent; the wire itself is noticeably thinner in one spot.

I replaced this wire (thermostat block to element) with a fresh length of 12 AWG, cleaned up, and all seemed well (sort-of ;-) Two Days later the reset button on the upper element tripped, so I figured I would change the elements for 2 new ultra low density elements.

Drained tank. Upper element was bent and so encrusted that it was difficult to remove (had to chip sediment off it by "stabbing" at it through the hole with a screwdriver). Lower element VERY VERY hard to turn - a #3 Phillips screw driver through the element socket deflects in the effort to turn the element, and you can HEAR "shhhhhh" when it does turn just a bit.

I'm amazed, but I think the lower element is completely buried in sediment! An ohmmeter on the disconnected element measures 80 ohms. I think it should be about 15 ohms, like the new ones. No short to ground though, so I'm guessing that the problem is an intermittent short.

Concerned that I may snap off the element, I decided to leave it there (re-tightened) and replace just the upper element for now. I figured that even if I get the lower element out/off, I would not be able to remove all the built up sediment.

It appears to be working for now, but I figure I'm on borrowed time. So I'm planning to replace the unit with a new 50 gallon electric heater (our family of 4 really doesn't need 80 gallons!). Do I have any other options that make sense, or have I diagnosed this properly?

I'm assuming that if the previous owner had flushed sediment out of the system every two years or so, these problems could have been avoided. Is that right? (previous owner seems to have done very little in the way of regular maintenance to the house)

I'm also assuming that the change in tank size will mean that my existing pipes may not line up with the new unit's hookups, so there will be some fun there :-) Any other gottchas or issues I should be aware of?



Replace this thing and forget it. Do it now. Everything you've found is telling you it's toast. From your description, I'm surprised the tank hasn't yet fractured. If it's located in a place where leakage from it would not be able to drain away and would cause damage, you're very likely at extreme risk.
You can put a 30-micron sediment filter on main-supply from the well for general principals (easy and cheap) but be advised it probably won't save you from another replacement in ten years or so. What you've seen with this one is exactly what will happen to the next one also. That's just how it is at your location. Regular purging can delay the inevitable by a little bit but probably not a lot. If you can find one with a 15-year warranty, consider that.