College uses geothermal design
The Trane Company was selected as the supplier of one of the world’s largest closed-loop geothermal hvac systems, totaling 1,741 tons, for a college in Pomona, N.J.
Founded in 1971, the Richard Stockton College is a mid-sized liberal arts and sciences college located in the southeastern part of the state. The project design featured 400 heat exchange wells located in boreholes to a depth of 425 feet. These were installed in a 3.5 acre area that included all of one of the college’s parking lots plus some adjacent open space.
Only pure water, without glycol, was used as the heat exchange medium, because of the area’s Pine Barrens protected environmental status.
Heatec Inc. of western Pennsylvania developed the final design with Anderson Engineering as a subcontractor installing the ground loop system and external horizontal piping. The boreholes are 4-in. dia.
Within the 4-in. borehole, the installers placed two 1.25-in. high-density polyethylene pipes with a U-shaped close-return coupling at the bottom. Installation of the pipes was complicated by the fact that the boreholes filled with groundwater and the pipes became buoyant. Installers overcame this problem by attaching weights to each loop and filling the heat exchange pipes with water.
In total, the loop system comprises 64 miles of heat exchange pipes. The individual wells were connected to 20 4-in. dia. lateral supply and reverse return pipes using a thermal butt fusion technique. These laterals, in turn, run to a building at the edge of the field where they are manifolded into 16-in. primary supply and return lines.