"Donna Ohl, Grady Volunteer Coordinator" wrote:

What's the easiest way to compare heat leakage between two water heaters?
Look at the yellow energy label on the heaters. The annual cost to operate
printed there can be compared on different models.

Are you sure?


Yes

Isn't the Energy Factor a more pure number than the annual costs?

Yes.

That is, the energy costs depend, of course, on the price of energy and
volume of water assumed while the Energy Factor should be independent of
those two numbers.

So, it seems to me the EF already takes into account the insulation (and
whatever other factors matter).

Doesn't it?

Do you care? Consider the case where one heater has poor insulation and a very
efficient burner, and the other has a poor burner and better insulation. Both
have the same EF, both cost the same to operate over a year. Which one do you
buy?