That t-stat with round pin was the problem.....it is set to OPEN at 160*F and close at 130*F
As posted earlier
Correct t-stat (small terminals) Opens at 140*F closes at 110*F
ECO (large terminals....same one used for both standard and XT models) Opens at 180*F and closes at 150*F
Wrong t-stat/correct ECO....overheating due to high temp set point of wrong t-stat
Original issue could have been as simple as dirty contact on circuit board connector, loose spade connectors on terminals or t-stats not being held tight to WH Tank wall.
