On Sun, 30 Jan 2005 11:16:27 -0500, "William Deans"
wrote:

Greetings,

For the purpose of heating efficiency is generally measured as
BTU heat output / BTU fuel purchased.

You get 100% efficiency with vent-free gas heaters.
You get over 100% efficiency with heat pumps. The is because some of the
"BTU heat output" comes from the air outside of the house rather than the
fuel purchased. This is why over 100% efficiency is possible -- even with
gas.

Hope this helps,
William

Obviously, what you really want to know is how much you are paying
to heat your house. The cost of gas versus the cost of electricity
determines which one is most economical.
In most areas of the United States today, natural gas is MORE
economical to heat their homes than heat pumps. Some geothermal
units are more economical on an energy used basis, but not enough that
the extra installation and maintenace cost are ever recovered.