How common are the loop temps for ice storage systems to even be OK to use a GTHP off the shelf, already made to 75 tons in the 1990's, which can run to suction temps around 8 degrees as built already?
I mean since the GTHP already can have icing-re-circulation temps at 24f entering something regularly, receiving 27 and 26 f back to a system off the shelf, then a water:water hp unit off the shelf may save a dollar with its already 35+ year longevity, properly installed, respectively.
ref:
geothermal system in combination with Ice storage in
the Southern states? Let's add heat recovery to offset some of the costs
http://cr4.globalspec.com/comment/551361