My two geothermal units (basement and attic) were installed without any insulation on the water lines to and from the units. 3/4 copper in the basement and 3/4 poly (hard plastic tubing) to the attic.

I have just been running the units for the first time this week... and when in heat mode, the return line is sweating and dripping like crazy, since the return water is pretty cold and lower than the dew point. I can wrap these in pipe insulation and I assume that will keep the moist basement air from contacting the cold surface and should solve the problem there... my concern in the walls of the 1st and 2nd floor where the tubing runs to and from the attic unit. It is also not insulated and I am concerned that it will be sweating in the wall and causing mold problems. My trim has not been installed yet so now is my last chance to remove drywall and insulate the pipes before trim and paint are complete.

Does anyone else on here have a system in the attic? Were your supply/return water lines insulated all the way up to it?

BTW. My attic is in my building envelope (closed cell foam in the rafters)... so I am not concerned about freezing... only about sweating and moisture in the walls and attic.

Any advice would be greatly appreciated.

Jeff