On 09/09/2019 18:19, alan_m wrote:
Ground sourced can be viable but this costs more and care has to be
taken with the design of the installation, as some local councils have
found when implemented on some of their estates.

all those abandoned deep coal mines were so hot the miners
worked in shorts and tee shirts, so I'm surprised they
haven't been re-used as a ground-source district heating
system.