On 30-Mar-2004, "Lou" wrote:

Temperature rise for water: 53 degrees F (114 - 61)

Um, not quite. The temperature differential your heater is maintaining is
53 degrees. The temperature rise for the water is the difference between
temperature of the cold water coming into the tank and the hot water coming
out. The air temperature in the vicinity of the tank doesn't tell you what
the inlet temperature is - it could be warmer or cooler

My analysis was to measure the energy loss for an IDLE water heater. No water
was drawn from the heater during the test, so the incoming water temperature is
irrelevant -- there was no incoming water. The 53 degree figure is the
difference in the temperature between the water in the tank and the ambient air
temperature. That figure is significant because the heat loss is directly
proportional to the temperature differential.

And all these years, I thought the energy guide labels were from the
Department of Energy, not the EPA

You may be right about the department. I'll have to go under the house to
check the label again.