Sounds like your roommate fell in love with your new 50 gallon hot water
tank.
I think you mother objects to your lifestyle, and she is sneaking around
your place at 1 AM, to turn the hot water off. She knows your girlfriend
showers before you, and she is targeting you for a cold hint that the girl
has to go.

"Ringo Langly" wrote
A quick history -- I bought my home 2 years ago

About about a month after installing the 50 gallon hot water heater I
got a roommate, and that 50 gallon has been working great until two
mornings ago when i went to get a shower and ran out of hot water after
maybe 3 minutes. I asked my roommate if she took a long shower, and
she hadn't -- plus the washing machine nor dishwasher had been running
- this was in the morning before work. Neither of us have changed our
routines, and every morning since she moved in 6 months ago we've had
plenty of hot water to spare.

Any ideas?? This sucker is a pain to replace, so I hate to replace it
again -- but I like my hot showers more

Thanks or any advice or suggestions.

Ringo