dennis@home wrote:

Given that the average air temp in the UK appears similar to the ground
temp

No.

Thats incorrect.

air varies at this time of year from may +5 to -5 here anyway = over a day.

Subsoil is pretty constant at a meter down at about 2-4 degrees.

It's was a little warmer in winter, due to summer solar heat and
geothermal energy, and its never as warm in summer.

ASir source can gice up at very low temps..-25C and you want see a lot
of eat out, when youy need it.

They are beter in urban situations., because you can pump waste heat
from all tehe cars :-)


how much extra does a GSHP save over an ASHP? I was toying with the
idea but I would need a bore hole for a GSHP and they are not cheap.
Also as the heat for the GSHP is actually solar there must be a problem
replacing the heat in the bore hole if the neighbours also decide to
drill them, there isn't enough land in the cities to absorbed the solar
radiation needed.


geothermal...there was a nice Swedish scheme that use the (insulated)
ground under the house and a pond in summer to run the aircon. Heated up
a huge block of subsoil, and pumped it all back in winter. Cool idea.

I wonder if BT or the cable co would notice if I pulled my collectors
along their ducts?

would be **** all use if you did. need contact with wet soggy ground.