Ground Loop Configurations

• Horizontal Closed Loop
• Vertical Closed Loop
• Well-to-Well or Open Loop
• Lake or Pond Closed Loop

Your contractor will recommend one of these four ground loop designs.

The recommendation will be based on: the size of your home and yard; your home's design heat loss; soil conditions; equipment sizing; use of a desuperheater; required entering heat transfer fluid temperature; and the availability and quality of groundwater.

Horizontal Closed Loop

Best for:

• Rural areas where space permits; areas where soils can be easily excavated; land with high moisture content is optimal for these systems.

Considerations:

• Requires more land area than any other loop system. The pipe is generally buried in a trench, usually 2 to 3 metres (6 to 10 feet) deep in one continuous loop or a series of parallel loops.
• Proper design is critical, since horizontal pipe lengths can vary between 91 and 914 metres (300 and 3,000 feet) of pipe per tonne of heat output.
• Rural properties of over one acre are typically best suited for horizontal configuration.
• Not recommended in dry sands and gravels.

Horizontal loop designs include one-pipe, two-pipe, four-pipe, and slinky coil configurations. The most common are two and four-pipe configurations.

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Vertical Closed Loop

Best for:

• Homes with limited available land area, or where other loop configurations are not cost-effective.

Considerations:

• Vertical loops require fewer feet of piping than horizontal loops, since ground temperatures are more constant at a depth of about 6 metres (20 feet) or deeper.
• Vertical boreholes measure approximately 13–18 centimeters (5–7 inches) in diameter and are typically spaced 10–20 feet apart.
• A pair of 3/4–1 1/4 inch pipes are inserted in the borehole connected by a u-bend assembly on the bottom. The pipes in each of the boreholes are tied together in a trench 4–6 feet under grade.
• Proper design is essential since pipe length can vary from 91 to 183 metres (300 to 600 feet) per tonne of heat output.
• Your contractor may drill a test borehole to determine soil conditions to confirm loop length and design prior to system installation.

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Well-to-Well or Open Loop

Best for:

• Homes with access to a good supply and quality of well water. Open loop systems extract heat directly from well water. Well water is pumped to the heat pump system from a supply well, and is then returned to a second well or "return well".

Considerations:

• Typically, the entering water temperature of an open loop system is approximately 6 C higher than a closed loop system. Higher entering water temperatures can lead to improved efficiency of the geothermal heat pump system.
• Water sources with high levels of salt, chlorides or other minerals can cause premature system failure or inefficient operation.
• Annual cleaning and maintenance of the heat exchanger(s) by your installation contractor in your heat pump furnace unit will be required to reduce mineral scaling.
• Pumping power may become an issue in installations that require deep supply wells.
• Approvals from the appropriate environmental authorities in your area may be required.

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Lake or Pond Closed Loop

Best for:

• Areas with a pond or lake nearby and poor drilling/excavation conditions, where the loop field can be submerged in water, rather than buried in the ground.

Considerations:

• Approvals from the appropriate environmental authorities in your area are required (i.e. Department of Fisheries and Oceans).
• The loop field must be:
  • properly anchored to remain on the bottom of the body of water;
  • submerged deep enough under water;
  • protected at the shoreline to avoid being dragged away by the movement of spring ice break-up.
• Lake/pond system is an extremely specialized configuration, so important that an installation contractor has sufficient experience and understands all aspects of this type of installation

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