David, thanks for catching and owning up to your own error ;-).  Of course, for the comparisons to be complete and properly related to the point in question, one would need to calculate total life cycle energy use, not just energy use by the unit itself.  Consider transportation energy use for the propane, and transmission loss for the electricity for example.  Efficiency of the power plant itself would need to be taken into account.  It is a complicated matter.  DMc

---- David Beierl <dbeierl@attglobal.net> wrote:
> At 10:35 AM 6/10/2010, mcneely4@cox.net wrote:
> >Well, you did the numbers David, so I bow to you.  DMc
>
> Yah, but I did them wrong.  The furnace at 80% efficiency will
> consume 6250/hr, not 7500.  The A/C still wins, but not by so much.
>
> :)
> d
>

--
David McNeely