On Dec 4, 7:40*am, Edward Reid
wrote:
On Fri, 03 Dec 2010 08:02:49 +0100, Sjouke Burry

wrote:


A heat pump (which is also electric) is more than 100% efficient, in
the sense that the thermal energy delivered to the interior is greater
than the electrical energy used to pump the heat. This applies to an
interior temperature of about 70F and exterior temperature down to
about 15F. With a greater temperature difference (exterior below 15F)
the heat pump efficiency drops below 100% and you are better off
switching to resistance -- as some heat pumps do automatically.

Edward

That is called the Coefficient Of Performance.
http://en.wikipedia.org/wiki/Coeffic...rmance#Example