In Reply to: Plumbing Puzzle posted by Jack - Iowa on June 10, 2018 at 13:16:13:
Water Heaters can recover rather quickly, even when there is one element burned out. Then you get less then half of the normal hot water, depending on which element burned out and if their temperature controls are set the same.
Questions are: How big and how old is the water heater?
How old is the Valve on the shower?
Did anyone else take a shower or run the dish washer or cloths washer before her? Are you on a well?
My Guesses would be in this order: 1. One element in the water heater is burned out and it is only heating the water in the top of the tank. 2. The temperature controls that turn on the heating elements have gone bad. 3.The balancing valve in the shower got stuck when someone flushed a toilet while the shower was going. 4. The Dishwasher or cloths washer filled at the same time she was in the shower.