wrote in message
...
On Dec 14 2007, 1:19 pm, lanman wrote:
On Fri, 14 Dec 2007 10:29:27 -0400, Paul M. Eldridge



wrote:
Hi Dan,

A standard billing measure for natural gas sold in the U.S. is a
"therm". One therm contains 100,000 BTUs. Alternatively, it is
sometimes sold in 100 cubic foot increments (CCF). Assuming a gas
furnace with an AFUE rating of 92 per cent, your net heat gain in
either case is about 27 kWh.

Natural gas prices can fluctuate widely from one year to the next, but
according the DOE, the average retail price for natural gas sold in
Washington state in 2006 was $1.34 per CCF. Again, assuming an AFUE
of 92 per cent, that puts the equivalent cost per kWh in the range of
$0.05. As of September 2007 (the latest month for which data is
available), it is $1.63 per CCF or $0.06 per kWh(e).

The current minimum HSPF or "heatingseason performance factor" for
air-source heat pumps is 7.7; like AFUE ratings, higher numbers are
better. A good quality heat pump with a HSPF of 8.5 will provide, on
average, 2.5 kWh of heat for every kWh of electricity consumed. If
you currently pay $0.08 per kWh, your effective cost per kWh of heat
falls closer to $0.03. On that basis, the operating costs of a high
efficiency natural gas furnace are 1.5 to 2.0 times higher than that
of our reference heat pump.

If my memory is correct, domestic natural gas production peaked in
1973 and the U.S. has been relying on natural gas imports from Canada
and Mexico to make up for the slack (and to a growing extent, LNG
imports from overseas). Canada's natural gas production has also
peaked and so I expect natural gas prices to trend upward going
forward (a succession of relatively mild winters and the loss of major
industrial consumers has helped to temporarily dampened prices, but
this won't last forever). Over the long haul, a heat pump would
likely outperform natural gas by a wide margin.

Hope this information is helpful.

Cheers,
Paul

In the past, a heat pump was not viable for regions with severe
winters such as New England. Has this changed? In what temperature
range will heat pumps perform adequately? I'm looking for alternatives
myself. Thanks...

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The heat pump is important; but the real key to low-cost, efficient heat
transfer in cold climates is the source of heat. Air is not a good heat
source in cold climates; but the ground or water might be. Here in northern
Ohio, we see more ground source (geothermal) heat pumps. What seems to
have changed is how the heat transfer coils are installed in the ground.
Instead of trenches, vertical shafts are drilled. These can go through rock
layers and require less land area.. Sometimes water is used if the water
table is high. Ground temperatues of 45-50F are the heat source during
winter and the heat sink during hot weather. See:
http://energymatch.com/features/arti...p?articleid=46 or
http://www.gcbl.org/node/2233/398#comment-398