I have a 40 gallon electric hot water heater in my apartment. The hot water runs out after a 10 minute shower, by the end of the shower I can turn the cold side all the way off and the hot all the way on and it is freezing cold. This is a new hot water heater (supposedly) because they replaced both elements and thermostats in the last one and that did not solve the problem. So, how long should 40 gallons of hot water last? And if the problem isn't in the elements or thermostats then what else could it be? The maintenance crew seems to only think it can be the elements or thermostats. I did turn up the temperature to 150 and that did not help.