Ground source pumps

Here's another visible portion of the geothermal ground-source heat pump. The system works around a fluid that is circulated through coils buried in the front yard and then sent through the heat pump. The liquid coming in from the yard comes in at the temperature of the ground. The pump converts that liquid into hotter or cooler air, using a compressor loop (the same that's used in a refrigerator). In this case, the working fluid is a combination of ethanol and water.