How to Harness Low Temperature Geothermal Heat Using a Centrifugal Chiller

Examine all local building regulations to ensure that a geothermal heat pump installation complies with the rules. Consult your local power utility to ensure that the pump does not interfere with the utility’s distribution network.

Make a thorough investigation of your proposed geothermal site. Identify any underground utility lines or obstacles such as sewers that must be avoided during the installation. Determine the site’s soil and rock composition and the depth of soil cover to plan the depth of the bore hole. Soil with more than 20 percent water content provides the best conditions for heat transfer from the ground.

Examine the hydrology of the site. The DX system does not usually leak refrigerant into groundwater but the depth of the aquifer is required to plan drilling procedures.

Hire a drilling contractor and geothermal installation contractor. Plan the depth of the bore hole. Ensure that the geothermal contractor has pressure-tested the copper tubing to be used to heat transfer. Drill a 3-inch diameter vertical bore hole to a depth of between 100 and 300 feet depending on your site investigation. Insert copper tubing into the bore hole. Back fill the hole with bentonite grout.

Dig a six-foot deep trench from the bore hole to the building. Lay the copper tubing at the bottom and back fill with bentonite grout and replace the soil cover. Use the hammer drill to make entrance holes for the copper tubing through the building walls at basement level. Guide through the tubing into the building's basement.

Place chiller on a firm surface that is covered with a vibration absorber. Connect the copper tubing to the chiller. Seal the spaces between the wall and tubing. Ensure that the geothermal contractor pressure tests the connected tubing and chiller. Connect the chiller to the building's heating system.