All the posts I've seen so far for Geothermal for Baseboard Heating have been pretty negative, but none have mentioned the Carrier/Bryant gt-pw water-to-water (50yew). This seems to be advertised as a boiler for hydronic use. It's specs are 140deg water with 32 deg EWT at 2.1 COP or 2.5 at 50deg EWT. 140 deg water will deliver about half the BTU's as 180 deg water but in my case I have cast iron baseboard on almost the entire perimeter of each floor so that it is somewhat oversized. Cast iron also has at least 5 times the contact area of finned copper pipe, so it would seem that it would perform better at lower temperatures and flow rates.
This unit is expensive and I obviously don't want a failed experiment, so I would appreciate any comments and analysis.