Systems Overview

This type of loop configuration is often the most economical to install where adequate space is available and the soil allows contractors to dig trenches easily. A series of parallel pipes are laid out in trenches below the frost line 1.4 to 2 metres below the ground surface. Typically, from 200 to 300 metres of Medium Density Polyethylene pipe is installed for 4kW of heating and cooling capacity.

This type of loop configuration is preferred for buildings with large heating and cooling loads, when the earth is rocky close to the surface, or for applications where space is limited. Contractors bore vertical holes in the ground 45 to 140 metres deep. Each hole contains a single loop of pipe with a U-bend at the bottom. Bentonite back fill with plugs at every 15m ensures that the heat collector functions to its optimum ability. The reason for plugging the bore-holes is to ensure that no possible contamination that may exist in the aquifers in the ground can leech out and into the system.

If the building or buildings are near a pond or lake, submerging the loop beneath the surface of the water is often the most cost-effective design. This type of loop configuration requires minimum piping and excavation, but the pond or lake must be deep enough and have sufficient surface area. The pipe may be coiled to fit more of it into a given amount of space.

Although this type of loop is used less frequently, it may be employed cost effectively if groundwater is plentiful. In this type of system, groundwater from an aquifer is piped directly from the well to the building, where it transfers its heat to a geothermal pump. After it leaves the building, the water is pumped back into the same aquifer via a second well called a discharge well a suitable distance from the first or ‘dumped’ into a soakaway area ie a river or lake.