Upper T-Stat Trip

kcopp

Every once and a awhile I get a service call for no hot water. I arrive to find a tank type electric WH sitting in the basement and the Upper T-stat ECO tripped. Sipmple remedy to get it going is to push the button and it starts up again. Most times I don't hear back a couple times though this will be fine for months and then I get a call back w/ the same issue.
Any reason other than a old upper tstat that this happens?

JUGHNE

After having been thru this many times, I reset once and manually exercise both T-stats and set back to the original positions. This may prevent repeating tripping.

If there is another trip, I would first ohm out the elements to ground for leakage. If they show good, I then change both the upper and lower controls. Usually never have to go back until the tank leaks or element burns out.

I do try to drain the tank if possible, some of those plastic valves have never been operated and triage is considered before attempting to open.
I always test the T&P valve regardless.

The lower T-stat is usually at fault and stick on stacking the hot water up to trip the limit. The HO might have reset the limit numerous times and that limit disc weakens.