For my location I feel the open system would be better. Well water at approximately 55 degrees is a real asset in the Summer. The winter would go along with this also as the water in the pond becomes cooler. I was thinking of installing 2 more large expansion tank so the well pump would run less often. Most of the articles I have read on using well water it has not created any problems. We loose enough water from evaporation to make the open system more desirable. The open system seems to be more efficient in heating and cooling. Very interesting topic.
