On Sun, 11 May 2008 16:26:42 -0500, "Pete C."
wrote:

Ground source heat pumps take care of that problem for the most part.

Hi Pete,

That may be so, but when you compare the economic performance of a
high-efficiency air source heat pump to that of its geo-based
brethren, the former prevails nine times out of ten and ten times out
of ten if you apply the difference in their respective cost towards
measures that further reduce the home's space conditioning and DHW
requirements.

Admittedly, that's a pretty bold claim but I've run hundreds of
different scenarios using various heat loss factors, weather data,
utility charges, install costs, discount rates, etc. and in my
experience you have to push the assumptions to the far extremes before
you can reverse the results. That said, I'm more than willing to be
proven wrong if someone can provide me with hard data and I certainly
wouldn't object to sharing mine.

Cheers,
Paul

Are you comparing the labor intensive old style deep hole or large
trench array, or the newer much better and much less labor intensive
trenched vertical coil installation?

Hi Pete,

According to the IGSHPA, vertical closed loops are typically more
expensive than their horizontal equivalents, as quoted below.

"Horizontal installations are simpler, requiring lower-cost equipment.
However, they require longer lengths of pipe due to seasonal
variations in soil temperature and moisture content. Since a
horizontal heat exchanger is laid out in trenches, a larger area is
usually required than for a vertical system. Where land is limited,
vertical installations or a compact Slinky horizontal installation can
be ideal. If regional soil conditions include extensive hard rock, a
vertical installation may be the only available choice. Vertical
installations tend to be more expensive due to the increased cost of
drilling versus trenching, but since the heat exchanger is buried
deeper than with a horizontal system, vertical systems are usually
more efficient and can get by with less total pipe."

Source: http://www.igshpa.okstate.edu/geothermal/faq.htm

Are you referring to something other than what is described above and,
if so, can you point me to some online references?

FWIW, I was told by a HVAC contractor based in Moncton, New Brunswick
that a typical 3-ton GSHP installation (new construction) runs in the
range of $25,000.00 for horizontal closed loop and $30,000.00 for
vertical (CDN). Does that more or less jive with your figures?

Cheers,
Paul