On Mon, 11 Feb 2008 14:44:50 GMT, Malcolm Hoar wrote:
EF is not the holy grail, unless you actually know for a
fact that your usage patterns mirror those assumed in the
EF calculation.

True but ... you can CALCUATE your personal situation (I'm doing it now).

READ THIS document (it's a MUST HAVE for water-heater calculations)!
http://tinyurl.com/38eh4d
(long url)
http://www.gamanet.org/gama/inforeso...vAttachmentLau
nch/C2AAFB8D41D003F485256E9000607F66/$FILE/12-07-gas-rwh.pdf

You'll also need your current costs per therm, e.g., read this (for me):
http://www.pge.com/tariffs
Specifically, these prices of approx $1.33/therm for gas-fired residential
water heaters in the local area:
http://www.pge.com/tariffs/pdf/G-1.pdf

Armed with those two documents and the FHR & EF ratings for your
prospective water heaters, you can do all the calculations you need to
apply to your specific situation.

I just wish there were a freeware water-heater calculator out there to make
this easier on all of us!

Donna
Note that it might not matter much as all water heaters are basically the
same according to this article (http://hkentcraig.com/2WHarticle.html).