Geothermal Rescue – Direct Exchange Heat Pump Repiping to Save Compressor – West Tisbury


This geothermal rescue involved repiping the refrigerant lines for a five ton direct exchange geothermal heat pump.  We were brought in to the project because the heat pump was overheating and not operating reliably.  The homeowner was concerned that long term damage would result and wanted to know why his system was malfunctioning.


hx details

We determined that the root cause of the overheating was the distance between the heat pump and its two heat exchanger modules – they were all too far apart and the compressor was working way too hard to meet the heating load.  One module was to create hot water for a radiant system and the other other module was to preheat water for use in the potable water system.


ball valves for line setsWe had to evacuate all of the refrigerant from this direct exchange system and start by adding ball valves to isolate the outside field, the hot water module, the preheat module, and the heat pump.





We then relocated the heat pump closer to the hot water module and preheat module to reduce the piping distance to within the manufacturer’s recommended distance.



heat pump with two dx by hx

We were then able to reorganize the line sets (copper tubes used for the refrigerant), braze them in place, and pressure test our work.





Finally, we were able to recommission the system by correctly charging the heat pump and direct exchange geothermal field and testing operation in the cooling and heating modes.   This work saved the compressor and ensured years of reliable heating and cooling operation.


Our goal is to be Martha’s Vineyard’s premier plumbing and HVAC shop – we appreciate the opportunity to show you some of our work.