puzzling hot water question

I own a brownstone with ten small apartments. A tenant who moved in a couple of months ago has been complaining about a lack of hot water for her shower. She says that it’s hot for two minutes and then cools off and by the end of the shower it’s all cold. I upped the hot water thermostat but it didn’t help.
The funny thing is that no other tenant has complained. In fact I specifically asked four tents about it and they said the hot water is fine. They all take their shower early in the morning before going to work, some before and some after the one who is complaining.
This tenant pays good rent and certainly deserves a hot shower. I just would hate to call in a plumber and spend money to investigate because I think it’s a weird situation. Don’t really know what to do.

By starfish1948 |