Installing a Geothermal Heat Pump: Step by Step

What happens before any digging starts?

The first visit is a site survey. The installer looks at lot size, access for a drill rig, buried utilities, soil or rock conditions and where the indoor unit can fit. A heat-loss calculation for the house follows, because it sets the size of the heat pump and the length of loop required. If that step is skipped, everything after it rests on a guess. The sizing principles are close to those in heat pump sizing for cold climates.

Permits and utility locates come next. Depending on the province and municipality you may need a drilling or well permit, a building or mechanical permit and an electrical permit. Lead time for these is usually the least predictable part of the timeline.

How is the ground loop designed and installed?

The designer chooses a vertical loop in boreholes, a horizontal loop in trenches, or another layout, based on lot size and ground. Horizontal and vertical loops behave differently and cost differently. For boreholes, the rig drills each hole, the crew lowers a sealed pipe loop, and grout fills the space around it. Drilling a typical residential field can take from a day to several days, depending on how many holes and how hard the rock is.

Trenching is faster per metre of loop but needs open ground. In both cases the crew pressure tests the loop before it is covered. If you have not yet picked a drilling company, the checklist in choosing a geothermal drilling contractor is a good companion to this page.

How do the header, pump and indoor unit connect?

Each loop is piped back to a manifold, often called a header, which collects the circuits and brings them into the house through insulated trenches. Inside, the heat pump connects to a circulating pump, the distribution system and the electrical supply. Distribution may be forced air through ducts or water through radiant floors, as discussed in radiant floor heating.

Drake Landing offers a useful contrast. Its 144 boreholes were joined by piping into a central field, and the heat moved through a district loop to each home’s air handler. A single-home system is much smaller, but the sequence is familiar: loop, header, circulating fluid, then a heat exchanger indoors. See the project’s borehole storage page for the larger version.

What is commissioning, and what should you get at the end?

Commissioning means the system is filled with a water and antifreeze mix, purged of air, flow-tested and started. The installer checks loop temperatures, flow rate and the temperature rise across the unit, then sets the controls and shows you how the thermostat works.

Before you pay the final invoice, ask for:

• Loop pressure test records and the driller’s logs.
• A commissioning sheet with measured flows and temperatures.
• A site drawing showing where loops and headers run, for future digging.
• Warranty documents and a maintenance schedule, for which see geothermal heat pump maintenance.

How long does the whole process take?

From first call to a running system, many homeowners should expect somewhere between a few weeks and a few months. Design, permits and contractor schedules take most of that time. Installation itself is often a matter of days for the loop and a few more for the indoor work. Winter ground conditions can slow trenching, so planning in the preceding summer or fall helps. Check current rebates and financing before the contract is signed, using the steps in geothermal rebates and financing.

One practical tip: ask the installer for a written schedule that names each stage and who is responsible for it. Delays most often come from permit queues and from drilling crews booked weeks ahead, so a schedule with dates and a clear contact person lets you see slippage early and plan around it, for instance by arranging temporary heat if an old furnace is being removed.

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