ELI5: How do they manage to constantly provide hot water to all the rooms in big buildings like hotels?

I've been doing commercial plumbing for around 7 years now, and never have we set the water temp to 160. The norm is 140° for kitchens/hospitals (because that's the temperature that you start to kill bacteria) and 120° for other domestic applications like bathrooms, etc. The point of the tempering valve is bring the temp to around 110° so that people don't burn themselves (on domestic applications). It would be hugely ineffective to heat the water to 160 just to have to temper it back down 50°.

I will mention though, that even there's an IPC (international plumbing code), it eventually comes down to your district's own plumbing code. So this could all simply be for my area.

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