I have a 4 ton closed loop system in which the slinky coil was trenched into an elevated pasture behind the house (the site was originally terraced cropland). I estimate 20 foot head between the coils and the heat pump in the basement. The unit has failed after 12 years of use. The coax corroded and was leaking coolant. In my research of installation instructions I have not found any specs on the elevation of the horizontal field relative to the heat pump. I wonder if the head pressure in the coolant line contributed to the failure. What do you think?
I don't think elevation matters in a closed system. I would be wondering about the original water that filled the system. Are you fixing it or replacing it?
I've replaced the heat pump. There was also an electrical problem with it; contacts badly corroded, and burned insulation. Using resistance heat now until the well company reconnects the field. The cap on the pump housing has seized shut, so I haven't been able to take a fluid sample for analysis. I'm hoping the well company can deal with it.