The heat pump seems to work well, easily heating the radiant floors. We
haven't seen anything below 35º F. yet. One
problem: The heat pump's copper tubing is strapped to the wall which
conducts some compressor noise into the home. Glenn says that he can
insert flexible tubing to fix this.
Note the last graph shows the solar gain. Even when the outside temperature is below 40º F we see the internal temperature rise above the thermostat set point of 66º F. This heat gain kept the heat pump from running until 3:00 AM. Our first builder said a GSHP wouldn't work with radiant floor heating, so we got a different builder, one that didn't care it it worked or not.
"Premier heating and cooling experts" in this area told us it wouldn't work. I put my first ground source air conditioning system in over 20 years ago. It used two wells instead of the vertical ditch system that we employ here. It worked fantastically well.