I have been thinking about geothermal for a few years but last year the gas company put in a gas main on my street. Running the numbers I find that there is no way geothermal can compete with natural gas for heating purposes. However, I am left wondering if it could make sense to use geothermal for cooling only? Specifically I want to compare costs of open loop geothermal to a high SEER conventional AC system. I did a crude water quality test/calculation that showed neutral to mild scaling potential so I think I am good for open loop. My ground water temperature is about 55 degF so the compressor sizing should be on the small side since it won't have to do that much work. Anyone have experience with open loop for cooling only?