Difficult to know...
I suggest you focus on TaylorBob1's number #3. It is not intuitive to someone who has always had "tanked" hot water to turn the hot valve on all the way and leave it there. Your temperature is regulated by the thermostat on the wall that controls water temperature. If you are mixing hot and cold water to attempt to obtain your favorite temperature, it will never get there. I see that your post was a few weeks back, so hopefully you have resolved your issues by now.
__________________
|