Mine is currently at 170F, with a 20F band. This means the burner shuts off at 180F and usually the temperature climbs about 5F taking the residual heat out of the heat exchanger. I normally run 140F at the heater but it also provides space heat and I need additional capacity in the winter. Of course I do have a honeywell mixing valve feeding the house.
This is true, especially with room temperature tap water, in the US we have been chlorinating our tap water for almost 100 years to prevent pathogenic bacteria. However specifically when heating water it can make it difficult to maintain the concentration of disinfectant necessary to prevent pathogens, primarily legionella. As I said in the video it is not generally a massive concern, but health officials do consider higher temperatures safer.
