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>In some modern homes the hotwater heater runs far above safe delivery temperature Is this a modern feature? It has been this way for as long as I can remember

• extrapickles 6y ago
  Its complicated, as at first you ran as how as you could to maximize the amount of hot water you had, then there was a period where it was seen as more energy efficient and prevented burns running at lower temperatures. "Modern" practice in this case started somewhere around 1970 where you have a termostatic valve (also called a Tempered Water System) to regulate the temperature of the resulting hot water to non-scalding levels.
• elric 6y ago
  Not sure if it's a modern feature per se. But if you have a tankless heater, you can set the temperature to be a little bit above the hottest water you require. If you have a heater with a tank, you need to keep it hot enough to prevent bacterial growth, specifically those that cause legionnaire's disease. I've seen systems with a tank, heat pump and solar panels, where the system automagically drives up the temperature to kill bacteria every once in a while. Supposedly that's more efficient than keeping it hot all the time.