New member here, and barely a novice when it comes to GeoThermal systems - please bare with me! We bought a new home in September that already had a GeoThermal system installed. I don't have access to the original installer, and the HVAC company I have been working with has been somewhat helpful, but I don't get the sense they are "experts". I will do my best to explain what we have, and the problems: Equipment: Econar GW770-1 Heat pump with PumpPak, Econar GeoSource 2000 AirHandler, 75 gallon holding tank, small buffer tank. My understanding from the previous home owner is the loop field is horizontal, due to the water table in our area so they couldn't do vertical. But I have no idea how long the loop is. First problem we had was the circulation pump for the ground loop fried (literally started on fire). I had that replaced, and found out from the HVAC technician they had replaced the other circulation pump last year. Looking at the pumps, the pump on the ground loop is larger than the other pump. Seemed odd to me. Second problem is compressor lockouts. When trying to raise the temperature of the holding tank, I cannot go any higher than 115F, or the compressor locks out with a "high pressure" error light. The HVAC technician said he thinks the problem is the buffer tank is too small, when I try and raise the temp too high the buffer tank cannot handle it, and it locks out - sounds reasonable, but I am not educated enough to know if that's just a guess, or most likely the problem. I noticed the last time it locked out that the holding tank pressure was 45PSI Third problem - The system cannot keep up once the temperature goes below 20 degrees. I recently turned the hydronic floor heat off, re-balanced all the ducts and opened vents, and it seems to be able to keep up if I am just running off the air handler. I noticed when I made this change, the pressure in the holding tank dropped below 10PSI. I've also noticed that it does not hold this pressure, i've seen it go as low as 5PSI. This doesn't seem right to me. I am not sure if the problem is the holding tank temperature is not high enough to keep up during the cold MN winters, or? I don't know what the ground loop pressure is, nor do I know what the in/out temperatures are. But I want to buy a guage, and temp probes so I can at least validate what these values are. I don't want to keep dumping money into possible fixes, without a better understanding of the system, how its operating, and the right data to better pin point what the problem(s) is/are. The HVAC technician suggested that the pump may be undersized, and the best solution long term would be to split the heating source between the air handler and watts hyrdronic in-floor heat. Which will cost thousands and this seems like a guess. I am sure I am leaving out details, please let me know what other information would be helpful. Appreciate any help!