On average, a geothermal heat pump (GHP) system costs about \$2,500 to \$3,500 per ton of capacity, or roughly \$7,500 to 10,000 for a 3-ton unit (typical residential size). In comparison, other systems would cost about \$4,000 with air conditioning.
When included in the mortgage, the homeowner has a positive cash flow from the beginning. For example, say that the extra \$3,500 will add \$30 per month to each mortgage payment. A 3,000 square-foot house in Oklahoma City (see below) has a verified average electric bill of \$60 per month, using a geothermal heat pump. This represents significant savings.
A system using horizontal ground loops will generally cost less than a system with vertical loops.
Geothermal heat pump installations in both new and existing homes can reduce energy consumption 25 to 75 percent compared to older or conventional replacement systems. Annual operating costs were also lowest with geothermal heat pumps. Add in the benefits of the desuperheater for hot water savings, and it's easy to see how a GHP system is the most efficient available.