said by Jack_in_VA:
How about our young, elderly and disabled? Why heat the water to 140 degrees when it's not needed and costs fortune to do? I do just fine at 120 degrees.
It doesn't cost more to keep at 140 than at 120 (not any amount that really matters anyway). The difference in standby losses is negligible compared to the amount of heat effectively used. You heat the water more, but you use a less of the hot water and more cold water.
Also 140F isn't that hot. And a mixing valve is a whole $35 and it shouldn't take a plumber more than 30min to install.