There is nothing wrong with setting one’s water heater tank very hot (except potential inefficiencies — there would be more loss when not using hot water, and h

There is nothing wrong with setting one’s water heater tank very hot (except potential inefficiencies — there would be more loss when not using hot water, and heat pump water heater can be less efficient heating to a higher temperature). Codes allow this. What codes do not allow is excessively hot water coming out the fixture. IMO this is the most sensible kind of code: it disallows a specific unsafe outcome. You are not allowed to build a house that burns unsuspecting users of the sink of shower. So you can apply technology! There are thermostatic mixing valves that can be installed near your tank to serve your whole house or at the individual fixtures. They’re not free, but they’re not terribly expensive, especially if just one is used for the whole house: https://www.supplyhouse.com/sh/control/search/~SEARCH_STRING=anti%20scald%20valve https://www.supplyhouse.com/sh/control/search/~SEARCH_STRING...