A Ground-Source Heat Pump for an Oceanside Home

A well drilling rig from Amherst, New Hampshire-based Skillings and Sons drills one of three 400-foot-deep vertical wells for the geothermal ground loop for a ground source heat pump (GSHP) heating and cooling system for a house on the Massachusetts shore north of Boston. Drilling three wells took the crew and rig two days on site. The truck carries sections of drill shaft in a rack; as the well gets deeper, the operators pause to attach new drill sections to the shaft. In the foreground, a water pump extracts groundwater flowing from the borehole.

Some geothermal wells are dry, but some produce water. This well produced 100 gallons per minute of fresh water after the shaft reached the water table, requiring a pump setup to extract the excess water as drilling continued.

The drilling crew dug this sump trench to manage the overflow of fresh water produced by the ground loop well shaft. Homes in the area have fresh water supplied by a municipal water system, but many also have drilled wells that produce water for use in landscape irrigation. Despite the area’s location on the shore of the Atlantic Ocean, the wells produce fresh water.

After the third well reaches the target depth, the crew withdraws its drill shaft from the borehole and stores the shaft sections in a rack on the side of the drill rig.

After completing the final well shaft, the crew pulls its drill truck away from the well, in preparation for inserting the geothermal ground loop tubing.

The crew smooths the grade around the well head with the bucket and blade of a skid-steer mini-excavator.

A crew member spins the top coupling off the well casing, prior to inserting the geothermal heat exchange tubing for the heating and cooling system’s ground loop.

The crew inserts the end of the ground loop into the top of the well shaft. The end of the tube is stiffened with several sections of rebar, lashed together with rubber tape.

Two crew members guide the tubing into the well shaft while a third unrolls the tubing from a trailer-mounted spindle.

As the air-filled plastic tubing descends into the groundwater-filled well shaft, flotation becomes an issue and the crew has to fight against the buoyancy of the tubing. At that point, the crew connects the tube to a water spigot and fills the tubing with water to eliminate the buoyancy and equalize the weight, allowing the tubing to descend more readily into the shaft.

Once the full length of tubing has been inserted into the well shaft, the crew continues to run water into the loop in order to flush out any remaining pockets of air. When the spurts of mixed water and air change over to a continuous flow of water, the crew will disconnect the tube from the water supply and clip the ends.

A crew member clips the end of the plastic tubing.

A crew member secures the tubing loop to the well shaft with an optic-orange comealong strap, and seals the ends of the tubes with rubber tape. The well head is now ready for the next step: connecting the ground loop to the house.

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