Quote:
Originally Posted by Ormston
GSHP manufacturers usually require glycol in the ground loop to protect against freezing the evaporator HX (controller usually shuts down at -5 to -10C), it's quite normal for the water being returned to the ground loop to be sub zero.
Steve
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But that does mean that you are freezing the ground. Of course there will be a significant amount of heat at that point because of the release of change-of-state heat.
But this will impede the ingress of ground water and all the lovely effects that the paper outlines.
ALSO... If you are circulating sub-zero water around your foundation, are you not freezing it, and exposing it to ground heaves, and cracking??
To say nothing of the foundation becoming a 'super sponge', thermally speaking.
-AC