water heater high temp. switch
 

I have a single element electric water heater. The high temp. switch will not stay made. I'm having to push the reset button on the switch every few hours. Any ideas?

How old is it?
I think you mean the thermostate not the high limit switch.
Check for loose connections there and back at the panel. A loose connection will cause a faulse trip.

When the Hi limit switch is popped it is telling you that the water is too hot (usually about 160 - 190 degrees ) . The main reason for the water to be too hot is the thermostat is malfunctioning . I would start with replacing the thermostat and a new hi-limit thermostat.