You can use a close loop, but there are disadvantages. First is the cost of the loop. These are not cheap and can run $10,000 or more depending on the size of the loop. If heating is important for your climate, loop systems run at cooler tempertures. 35-40F. Ground water is 52F. There in a lot more heat in 52F water. As a result, loop systems require larger units to make up this difference. In my installation, every unit was reduced a full ton in cooling by simply commiting to ground water. I saved over $4,000 including the electricity to run them. Pump and dump systems have two disadvantages, one; do you have a place to dump the water. I use my pond which over flows to a wetlands. In the winter time if you're in a cooler climate, you'll go through a million gallons of ground water. The second disadvantage is you need an upgraded very dependable water source. This will cost more bucks. Most of the water the well puts out will be consumed by the geothermal units. Your personal use is minimal. If you can fulfill these two disadvantages open loop is the only way to go. Higher efficiency and lower equipment cost, with no glycol loop system to deal with.
