On Mon, 18 Feb 2008 06:55:46 -0800 (PST), wrote:
on energy costs, this heater was designed after the energy guide label
specs were created, thats why its energy use is under the lowest.

Interesting!

The Energy Guide label for this 0.63 Energy Factor water heater:
http://www.flickr.com/photos/donnaohl/2274085480/

Says the thermal energy factor comparison is:
This model uses 238 therms per year.
Uses least energy: 242 therms
Uses most energy: 272 therms
Only models with FHRs of 87 to 99 gallons are used in this scale.
This model's estimated yearly operating cost is: $216 dollars
Based on a 2004 US Government national average cost of 0.9100 per therm.
(41,045 btu/0.63)($0.9100/therm * 1 therm/100,000 btu) x 365 = $216/year

However, my estimated thermal energy factor is closer to:
(41,045 btu/0.63)($1.21106/therm * 1 therm/100,000 btu) x 365 = $288/year

So, the Energy Guide label is off on energy costs by a whopping 75 percent!
(I think.)

Donna
PS: I never know whether the best calculation is this way or that?
$216 / $288 * 100 = 75%
or
$288 / $216 * 100 = 133%