Kevin[FONT=Tahoma][size=2], a check of your weather records shows in the last 48 hours it was well below freezing at night (14°) and at freezing during the day. Previously to this, temperature was moderate.[/size][/FONT]
[size=2][FONT=Tahoma]The colder it is, the longer the run time, the colder Loop field becomes. Just because the loop is below 32° does not mean there is not substantial heat left in the line. Compare this to the 14° area temperature that air source heat pumps must operate under during the same conditions. Extracting heat from 32° brine is a whole lot more efficient than 14° air.
[/size][/FONT]Just because there is ice present, does not mean there is something wrong[FONT=Tahoma][size=2]. Though there could be. What we’re looking for is a temperature differential of the actual fluid inside the lines. In your pictures I can see that one line is warmer than the other, indicating that things are working properly.[/size][/FONT]
The actual temperatures that you will receive depends on the design of the system and cannot be compared with other systems or a rule of thumb[FONT=Tahoma][size=2].[/size][/FONT]
There is no abnormal ice formation visible, just frosting of lines. The amount of frosting is also dependent on humidity levels within the mechanical room area.
One common problem with geothermal units is sufficient water flow/quantity[FONT=Tahoma][size=2]. Scale builds up and reduces flow and will cool these lines to a colder temperature than desired. So, were not necessarily out of the woods. In these cases I generally ask who servicing contractor is and give them a call.[/size][/FONT]
Other geothermal designs are more consistent than the ground loop because water is taken from greater depths or have a better heat exchange rate than the soil[FONT=Tahoma][size=2]. The ground loop will probably give you the greatest consistency problems.[/size][/FONT]
I know this isn’t much help, but it may expand your concept of what’s happening.