Loop Fields – Overview

lOOP FIELD ELEMENTSThe loop field is arguably the most important part of a geoexchange system. In many ways the loop field is like the gasoline tank on a car. It stores the energy, in this case heat from the sun, to be used as needed in the home or building.

In the winter the loop field absorbs heat from the ground and brings it into the heat pump located in the building. In the summer cooling season the process is reversed; the heat pump removes heat from the house and uses the loop field to carry it into the ground where it is absorbed by  the cooler earth.


Types of loop fields

  1. Vertical – Loops are installed vertically between 100 and 300 feet deep using well drilling equipment
  2. Horizontal – Loops are installed horizontally 8 to 20 feet below the surface through trenching or with horizontal boring equipment.
  3. Pond – Pond loops use either high density polyethylene pipes that are placed in a ‘slinky’ configuration, or a stainless steel plate heat exchanger.  The chosen product is then submerged in a pond.
  4. “Pump and Dump” – Instead of a loop field, the heat pump uses water from a well to heat and cool the home. Once the water go through the heat pump it is “dumped” into the ground or a body of water. The State of Minnesota has passed regulations effective January 1, 2015 that will largely prohibit the use of this loop field in most every situation.   —More

Materials & Warranty

SAM_9343High Density Polyethylene Pipe (HDPE) is considered top of the line for geothermal piping because of its superior rigidity, thermal properties, and chemical resistance. This is the same material that is routinely used in city sewer and water pipes.

HDPE carries a 50 year warranty and has been aged out to 100 years. —More


Antifreeze

pb_non_toxic_symbol

Loop fields are buried well below the frost/freeze level and, therefore, seldom every freeze up due to external temperatures. But an undersized system operating in extreme conditions can go cold or freeze. So Food grade antifreeze is added to loop fields as an extra layer of protection against freezing up in extremely cold conditions. —More


Loop Field Design

Loop fields are custom designed based to meet the specific BTU requirements of the home or building. Three basic criteria are consider for each installation.

  1. Space available – The more space available the more options there are for loop field designs.
  2. Thermal conductivity of the soil – This helps to determine how many loops are needed and how long each loop will have to be.
  3. Costs – Cost is typically a deciding factor when more than one loop field will meet the needs of a specific system.

Geo Link DesignCompetent loop field designers will use one of several software packages that are available for loop field designs. The designer loads in the appropriate data and the software develops the loop field specifications and performance measurements.  —More

 


Installation

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Vertical Drilling

Drilling

Vertical Loop fields are installed using well drilling equipment. Wells are drilled down between 80 and 300 feet.

Once the hole is drilled to the correct depth the pipe is inserted into the hole, and the hole is filled with a bentonite grout.

Vertical drilling requires large equipment that can do significant damage to lawns and landscaping.  –More–

UMR Horizontal BoringHorizontal Boring

Horizontal boring equipment is used to install horizontal loop fields. This equipment  installs the loop field 15 to 20 feet underground with very minimal damage to yards and landscaping.

Horizontal boring requires a significant amount of space – typically a minimum of 300 feet.

UMR Vertical DrillingTrenching

Trenching used to be the only method of installing horizontal loops before the advent of horizontal boring equipment. Trenches were dug down 8 to 10 feet. The pipe was laid in the trenches manually, and the trench was filled in.

Trenching has fallen out of favor because of the limited depth that the loop field can be installed and because of the significant damage to lawns and landscaping done during installation.

Pond_Loop_Being_SunkPonds

Pond loops are assembled on land, floated out into the pond, and then sunk in the water until coming to resist on the floor of the pond. They require minimum excavation and do minimal damage to yards and landscaping.

                                                                            —More