I have a problem with my hot water running cold after about 5min in the shower. The temp on the heater in turn to very hot but still after 5min it still runs cold. Please help because I love at least 10min showers.

This would normally point to the dip tube needing to be replaced. See HowStuffWorks "How Water Heaters Work" (http://home.howstuffworks.com/water-heater1.htm)