The same thing happened to me a number of years ago--extremely hot water and
then no hot water with the reset button on the upper thermostat popped out. It
turned out to be a lower element that had grounded itself out. The lower element
has 120 volts applied to each end of the element all the time, for a total
voltage of 240, unless the water has gotten so cold that the upper thermostat
closes to heat up the upper part of the tank and disconnects power to the lower
element. What is now happening is the lower element is heating the water until
the upper thermostat pops on safety sensing extremely hot water. The current in
the lower element is not flowing from one end of the element to the other end,
but it is flowing from one end to ground and is constantly heating the water
without regard to the lower thermostat. Disconnect all power th the unit, and
disconnect the 2 wires to the lower element. Measure the resistance from each
screw of the lower element to the bare metal around the hole where the element
is installed. The resistance should be infinite---You will find that 1 screw is
grounded to the tank due to the element being shorted internally. Replace the
lower element and your problem will be solved.
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On Sun, 07 Feb 2010 17:00:53 GMT, firstname.lastname@example.org (Ron in
A "grounded" lower element is virtually the ONLY thing that can cause
the described sequence of events - the only thing that would cause
uncontrolled heating, which would then trigger the safety shotoff.
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