recently a long time customer of mine purchased a farm house that has a FHP geothermal HVAC system for the main house. It seems this system was installed about 8 years ago and was maintained by the owner. there are records of filter changes and humidifier repairs near the heat pump. one thing i noted was that at least once the "underground loop was flushed out" and that "glycol" was added (unknown amount) twice. It looks like they used PEC pipe underground but i am not sure of that. I did my first check-up of the system today and the system seems to be functioning OK. I have experience with water source heat pumps but this is my first with an underground loop. my temp. drop on the low side was 6/8deg. with a 44deg. water inlet temp. and 89# suction pressure (r-410a). I have been unable to get an answer as to what the static pressure in the undergroung glycol loop should be. the air handler is in the basement and my loop pressure is at 12# , there is also a nearly full gallon of glycol at site. This thing seams OK but I feel like a dentist doing eye surgery, i realy like these people and consider them freinds as well as good customers. I call for a "profressional, experienced, honest" second opinion. thanks in advance.