I live in a condo with two full baths. Had a new 'on demand' water heater installed 5 months ago by a reputable contractor. I use this bath/shower a few times a year to soak sore muscles. Well, last time I wanted to soak, the tub faucet gave HOT water on for a few moments, then ran luke warm. Meanwhile, there is plenty of hot water from the showerhead.
It was suggested that the Moen cartridge needed to be replaced. So, I watched TOH video on how to replace it. I did the replacement successfully.
However, I still have the same issue... OH, when the faucet is not on full force, the tub faucet seems to stay hot longer. What could be the problem?