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.
Your closed loop install at a glance seems high specially for a 2 ton system. But I have no idea where you live. You may want to get another quote. Horizontal or vertical for loop type? The only thing that jumps out at me with your calculations is the 30F EWT is only accurate for the dead of winter when the system is constantly running. It will be warmer in the fall. Also you may not have the well capacity at that depth of well you cite. You may have to go much deeper but I now very little about well capacity in relation to depth.
Moey, Thanks for the input. I did run the numbers for peak winter heating scenario. Your're right that mild heating seasons closed loop would probably gain more ground in efficiency. I'm limited to vertical loops. Don't have the space for a horizontal field. And this is for upstate NY. Well capacity is not a concern right now. According to state records most wells in the area get 10-20 GPM within 200'.
Id strongly suggest getting another quote before making a decision. Also a 2 ton system would not require much ground footprint for a horizontal loop. Maybe 150ft * 10 ft could probably be squeezed in smaller but it sounds like that may be out but just wanted to throw that out. Our horizontal system works fine and we are in Maine.
Where are you located and who is the installer which proposed the 2 ton for you? I'd argue that you would need 65 x 12 feet for the closed loop field, or a (2) 65 feet by 4 foot wide trench in any direction
