I am building a new construction this spring and will be doing geothermal. The house is a 1500 sqft ranch modular with an upgraded insulation package. The installer: Closed Loop $30,000 + $4,000 for domestic water well. I went to a geothermal installer to get an estimate on the geo system. The estimate is for $30k with a 2ton closed loop WaterFurnace system. Too much for my current budget. Simply cannot spend that much right now. Plus I would still need to pay for a domestic water well on top of the $30k. The self general contract project: Open Loop SCW - $17,000 I estimated an open loop install cost to be much less. A ClimateMaster HP, 300' SCW, 0.5HP variable speed Pump and misc components such as spin down filters, pres reducer, brazed plate HX , ect... The water table in our location is also very high; about 10'-15' below grade so I can get away with a smaller well pump to save on electric operating costs. Water quality in my area meets the CM install specs for open loop. My biggest question is if my calculation below is accurate. If I am right, the added cost of operating a well pump is mostly offset by the improved COP of an open loop system. Which means it would be absurd for me to drop and extra $17k for a closed loop system when it will only cost me a few $ a month more to operate. All heat pump capacities are straight from the CM install manual. Tell me if I made a mistake.