When I first got my Caldera I saw on the display that after 104 it has ut_1, 2, 3 & 4. I wanted to see what that was because there was nothing in the manual about it. Setting at those at differnt times raised the water temp to 105, 106, 107 and 108. If it is suppose to do that or not I do not know but I will not complain I LOVE the hotter water. I do not keep at 107 all the time, I keep it at 104 but will raise it before getting in then lower it after getting out.