My water lines are in the slab to start with. During the day and evening hours the water temp. in all areas of the house is fine, however, at 5 a.m. when I take my shower the temp. is 12 degrees less in all areas.. Please help me through this problem... Thanks, Ron

These days it's easy to redirect water lines using plastic (Pex) piping. If that's not possible, you can get tiny in-cabinet electric water heater boosters. I suppose you could also change the setting on your water temp twice a day, depending on how your water is heated.

How long did you run the water before testing the temp? On a slab it is not uncommon to see temp swings, particularly in a cold environment since you are trying to heat the slab.