I inspected a fairly high-end home ($1.8M) yesterday that had two separate water heater systems that each had a 16k BTU/hr on-demand, gas fired Noritz heater in series with a 6 gallon, electric water heater. Theory apparently being that it is cheap to electrically heat 6 gallons of water but when that ran out then the Noritz would come on. This seems a little self-defeating to me and I wonder what others think of this setup.
Excerpt from City Energy Code:
My example seems to make the 6 gallon electric w/h the primary thereby violating the City’s Energy Code.