Andy Hall wrote in message . ..
I have a couple of friends in Sweden with these.

My wife has relations in Sweden, and we have consulted them over the
IVT heat pup we are considering - they use these but have a lake they
use as the heat source (never less than 4C at the bottom of the
lake?).

Taking the heat from the ground does cause the plants to be delayed by
3-4 weeks in the spring compared with the immediate surroundings.

I've heard this, but in the UK it seems to be partly apocryphal - we
are a lot warmer than the Swedes, and laying under a lawn, between 1
and 2M down scarcely effects the surface temperature where the grass
is. We have a 2 acre lawn (South facing) that we intend to use for
this (3 x 50M trenches with 250M of "slinky" coils, vertically in 2M x
20cm trenches, backfilled with sand to 1M, then soil). The available
energy absorbed by the lawn, even on winter days, is many many times
what we are proposing taking from it.

They have to switch the system off for at least a month in the summer,
to allow recovery of the ground,

In Sweden maybe - here it should not be a problem... its been
suggested than in the winter we may see about 0.5C average temperature
reduction at the surface. I've been looking at some UK "Energy
Efficiency best Practice" reports (amongst others), and for us, the
rationale looks good, especially as we will use Economy 7 to boost DHW
temps, so we can run the pump at its optimum temperatures.

I'm going to the Homebuilding show at Wembley next w/e to speak to Ice
Energy and the other suppliers we are considering. Should be
interesting.... ;-)

Rebuilding and extending an old, messed about, house makes for,
well... interesting times (in the old Chinese curse sense)...

Thanks

Mike