On the day before Thanksgiving 2009 we completed the installation of a three-ton, ground-coupled, closed-loop geothermal heating and cooling system for John and Judy Call, principal owners of Home Energy, Inc. The system consists of the ground loop, heat pump unit, and flow center. The ground loop consists of two 300-foot boreholes with one inch SDR-11 geothermal pipe connected through a reverse return header system to 250 feet of 1.25" SDR-11 geothermal pipe. The 1.25" pipe runs from the boreholes in a 4' deep trench to the flow center and heat pump unit in the home. The unit, manufactured by Florida Heat Pump, is a 3-ton vertical unit, model # FHP ESO35. It contains a high efficiency two stage scroll compressor with 410-A refigerant and a microprocessor-controlled DC fan motor. The coeffient of performance (COP) for this unit is 5. The building load and engineering to size the system was performed by Geo Pro, Inc. of Elkton, SD. The heating load was determined to be 30,235 btu/hr (around 8,860 watts) and the cooling load 16,988 btu/hr (roughly 4980 watts).

The project began in October when the Florida Heat pump unit was ordered. The most suitable location for the boreholes was in front of the property. Several fifty foot maple and larch trees had to be removed to accomodate the drilling rig. The boreholes were drilled by Faxon Artesian Well and Pump of Sandown, NH. Installation of the 1-inch U-bend SDR-11 pipe and grouting of the boreholes was a joint effort between Home Energy, Inc. and Faxon Artesian well. To get the proper thermal resistance for the pipe in the borehole, 1500 pounds of Geo Pro Thermal Grout Lite was mixed with 6000 pounds of silica and water and pumped into the two boreholes. The excavation work for the trench that brings the 1.25" SDR-11 pipe to the house was performed by Homestead Construction of Haverhill, MA. Installation of the geothermal pipe, header connections and pipe fusion was performed by Home Energy, Inc. Once the pipe was fused it was then pressure tested to ensure the integity of the fusion joints. Pipe installation and backfilling of the trench was completed by mid-October.

Once the ground loop was installed the internal piping to the the unit location had to be completed. Because the home is an earth-berimed, super-insulated structure built on a radiant slab, the floors needed to be removed in the first floor bath, hallway and utility room to bring the return and supply to the flow center. This work was completed and the subfloor was screwed in place, awaiting delivery of the unit. A call to API of NH to double check the delivery date alerted us to the fact that the order for the unit had not bee placed. We were assured that they would assign a rush delivery to our order and we would receive it in two weeks. It arrived on November 3rd and Jim and Jamie Gaznick of Northside Mechanical and Home Energy, Inc. put the unit in place. Once in place, Northside Mechanical fabricated the new supply and return ductwork for the unit. Alan Conte of AC Electric and Home Energy then installed the electrical and PVC supply and return piping to the flow center and heat pump unit. The unit's HVAC ducting, flow center and electrical were connected and ready for startup. An appointment with the factory representative was scheduled later for that week.

When the factory rep fired up the unit it was discovered the unit contained no 410-A refrigerant. A new unit had to be ordered and shipped from Florida Heat pump. The new unit was finally installed and running on Thanksgiving eve. Preliminary calculations based on electric bills from December and January project the cost to heat the 2800 square foot home to be about $400 for the heating season. The bulk of the savings will be realized during the cooling season.