I have an electric water heater this about 10 yrs old. I have to constantly press the reset button because the heater runs out of Hot Water. When I press the reset button after a while the water becomes almost scalding hot and will eventually turn cold again, which forces me to press the reset button and it happens all over again.

Do you have any idea what is wrong with my water heater.

Thanks

Bad thermostat. a.k.a. aquastat.

I agree with northernheat, sounds right to me