sci.energy

On Mon, 11 Feb 2008 13:40:11 -0800 (PST), hallerb@ wrote:

> lets assume a 300 buck a year operating cost and it sounds like you
> might save 4% on a more efficent model.

Actually, the cost savings for a more efficient model is as follows:
CHOICE A:
Sears 33154 (marketed as Kenmore but made by AO Smith) FHR=97 EF=
(41,045 btu/)($/therm * 1 therm/100,000 btu) x 365 = $288/year

CHOICE B:
Home Depot 183-717 (marketed as GE but made by Rheem) FHR=80 EF=
(41,045 btu/)($/therm * 1 therm/100,000 btu) x 365 = $313/year

a. Additional cost of more efficient model = $882 - $747 = $135
b. Annual savings of more efficient model = $313 - $288 = $25 per year
c. Payback period = $135 / $25 * 365 / 30 = 65 months ( years)

The overall savings over the average lifetime of a home water heater is:
(13 years - years) * $25/year = $190

Donna