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Horizontal & Vertical Loop Installation

The size of the land parcel available and the soil type will largely determine the ground loop alternative selected. Where adequate land is available, the lengthy horizontal trench system is often selected. Where land is limited, vertical boreholes may have to be drilled to accommodate the loop. The installation method for the ground heat exchanger will vary by the type of ground loop heat exchanger selected. Another alternative is the slinky system. A slinky is a coil of piping which is placed into a trench and buried. Its advantage is that a large heat exchanger surface can be installed in a relatively small area.

The most common pieces of equipment used to bury horizontal loops are a: bulldozer, backhoe, vibratory plow, chain trencher or a directional borer. The choice depends on local site conditions.

Equipment is available to support the rapidly developing market. A trencher, with 4-wheel drive and power steering, and using a 75 horsepower diesel engine, can dig a 6 inch wide trench up to 6 or 8 feet deep. At the other end is a six-way backfill blade. Another piece of equipment is the guided boring system used to place horizontal bored U-bend loops. Generally, the machine that moves the least amount of soil will be the most cost effective.

Vertical installations require a drill rig. Boring holes for loop insertion and boring holes to find well water are two completely different tasks. The ground heat exchanger is much simpler. The borehole is generally smaller which reduces drilling time, and no casing is required because the hairpin shaped loop is the casing. Two techniques typically used are mud and air drilling. The objective is to install a specified heat exchanger length, not to reach a given depth. If 600 feet of borehole are required, two 300-foot boreholes are acceptable and may be more cost effective.