Water Heater properties

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I wanted to build up a model of my own, so I downloaded a DOE prototype midrise apartment from the online library. But when I check the water heater, I found it hard to understand all the properties, especially the Off/On cycle parasitic fuel consumption rate and Off/On cycle loss coefficient to ambient temperature. I mean, where did those values come from (some company website? etc...), or is there a standard or reference for that?

Thanks!