Stayed with a friend who had a big house in Guadalajara, and he had these point-of-delivery, heat-on-demand heaters in each bath (I think he had three or four). They worlked like a charm and the lag on hot water at the showerhead was dramatically short compared to what I've seen with a tank at the "other end" of the house. I have also considered just getting a second water heater for the far end of the house. Another option is a cross over valve that keeps the HW circulating back to the HW heater all the time, very slowly, so what's at the tap is already heated. Probably the cheapest solution.

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