The average cost of installing a geothermal Cost to Install Geothermal HVAC usually lies between $20,000 and $40,000 for most houses, with some cases even surpassing $50,000. The amount depends on various aspects such as the size of the house, the soil in which the system will be installed, and the kind of loop system involved. In most cases, the cost may be higher than expected because of the complexities associated with geothermal HVAC installation. However, the initial expense will be worth it because of its efficient operations and low energy costs.