I don't understand. > We really should be thinking of turning off water heating at times when we know for certain it's not being used, and only heat up water a

I don't understand. > We really should be thinking of turning off water heating at times when we know for certain it's not being used, and only heat up water anticipating usage. There's a lot of energy to be saved for modern smart homes (or anyone who cares to manually regulate, or simply has to because they're using wood burners and such). > That is assuming you don't use highly isolated water bodies as thermal batteries. First paragraph describes a tankless water heater. Second paragraph describes a classic water heater, with a tank. That's practically all houses.