Loop field work on your property: what to expect

What happens before the crew arrives?

Before any heat pump installation, the loop contractor needs a survey of the lot, a confirmed location for the field and clear utility locates. Buried gas, water, electrical and septic lines all limit where a borehole or trench can go, and a locate request is part of normal practice. The permit stage comes first, and the sequence is laid out in the guide to the geothermal heat pump installation process.

Walk the site with the crew lead and agree on the rig route, where the spoil and drilling mud will go, which plants or fences must be protected and where the header trench will enter the house. Photographs of the yard before work starts help later if a repair is disputed.

How does vertical drilling work on a lot?

A compact drill rig, often on tracks, is set up over each borehole position. It drills to the design depth, the crew lowers a looped pipe to the bottom, and the hole is filled with grout so the pipe is in contact with the ground. Drilling a typical residential field can take from a day to several days, depending on the number of holes and the rock. The efficiency and capacity of the whole system depend on that loop, as explained in borehole depth and spacing.

Expect noise from the heat pump installation crew and a muddy patch around each hole. Cuttings and water come to the surface and have to be contained, which is why the crew decides early where to pile the spoil. Large trucks may need a firm access path, and a soft lawn can rut.

What is different about horizontal trenching?

Horizontal ground source loops are laid in trenches dug with a backhoe or trencher. The work covers a much larger surface area, so more of the yard is opened, and it is generally quicker per metre of pipe than drilling. The ground has to be suitable for digging, and frozen soil in winter slows it. Pipes are pressure-tested and then buried with fill, and the surface is regraded. The layouts and their trade-offs are covered in horizontal and vertical ground loops.

How do the header, testing and restoration fit in?

Once the loop pipes are in, they are joined at a header and connected to the heat pump in the house through a trench, often below the frost line. The heating and cooling system is then ready for the indoor work of the installation. The crew flushes the loop, purges the air, fills it with the water and antifreeze mix and pressure-tests it before backfilling. The test results should be recorded. After that, the yard is regraded and the lawn can be reseeded or sodded.

Disturbed ground settles over the first season, so plan for some topping up of soil before planting. A restoration clause in the contract, describing who repairs ruts, lawn and fences and by when, avoids arguments. Dig-free spots can be planted again, but keep deep-rooted trees away from the header trench.

What affects the schedule?

Permits, driller availability, weather and the condition of the site have the biggest effect. Frozen ground, heavy rain or a late permit can push the loop work weeks later. Many owners schedule the loop for late summer or fall so the system is ready for the heating season, but lead times differ by region. Installation work indoors, such as the heat pump unit, ducts and controls, usually follows the loop, and commissioning ends the process. Ask the installation contractor for a written schedule with the dependencies, and compare it with the numbers in your quote using the drilling contractor checklist. Cost drivers are in geothermal heat pump cost in Canada.

Quick answers