Geothermal heating installation: what to know

What the job involves, what changes the price, and what to ask a pro.

What geothermal heating installation is

Geothermal heating installation puts in a ground-source heat pump. The job involves drilling or trenching a loop field in the ground, connecting it to an indoor unit and ductwork, and commissioning the system. It suits homeowners who want a long-life heating and cooling system and have the land and budget for a large ground job.

Signs you need it

  • The current heating and cooling system is old and you want one system that heats and cools with ground heat.
  • You have land for a loop field, such as a yard, a field or a lot that can be trenched or drilled.
  • You plan to remodel or add living space and want the heat source designed for it.
  • Your heating bills are high and the house has enough insulation to make ground heat worth using.
  • You want to replace a fuel-based heat source with an electric system.
  • You are building a new home or an addition and can plan the heat source and the loop field together with the site work

What the pro does

  • Survey the site, check the ground conditions, and plan the loop field, which is either vertical boreholes or horizontal trenches.
  • Locate underground utilities before any digging, and drill or trench the loop field to the planned depth and spacing.
  • Install the loop pipe, header and manifold, then connect them to the heat pump with the circulating pump and the flow loop.
  • Set the water-to-air or water-to-water heat pump indoors and connect it to the ductwork or the hydronic distribution.
  • Flush and pressure test the loop, and add the antifreeze solution the design calls for.
  • Commission the system by checking pressures, flow rates, temperatures and the controls in heating and cooling modes.

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Loop field type, vertical boreholes or horizontal trenches, which need different equipment and land.
  • Size of the loop field, which depends on the home's heat load and the ground conditions.
  • Ground conditions, such as rock, clay or sand, which change drilling or trenching time.
  • Access for drilling or trenching equipment, and the distance from the loop to the house.
  • Indoor unit and whether the house has ducts, radiant heat or both to connect to.
  • Electrical service and the circulator pumps needed to run the loop.
  • Landscape restoration after trenching or drilling, which varies by site.

What a written quote should spell out

  • The loop field design, the type of loop, the depth and the spacing of the boreholes or trenches.
  • Heat pump size and model, with the heat load calculation it is based on.
  • Drilling or trenching work and any equipment needed, listed separately.
  • Loop pipe, header, manifold, antifreeze and pressure testing, listed as separate lines.
  • Indoor duct or hydronic connection work.
  • Commissioning and warranty terms for the heat pump and the loop.

Questions to ask before you hire

  • Did you do a site survey and a ground assessment, and can I see the loop field design?
  • Who locates the underground utilities before drilling or trenching, and how is that handled?
  • How deep will the loop go, and how many boreholes or trenches are planned?
  • What antifreeze do you use in the loop, and how do you test the pressure?
  • Who pulls the permits for the loop and the heat pump, and will the work be inspected?
  • What does the warranty cover on the loop, the pump and the labor?
  • Who handles the landscape restoration and how is it done?

Red flags

  • The pro starts drilling or trenching without a site survey or a loop design.
  • The pro does not locate underground utilities before digging.
  • The pro cannot explain how the loop is sized or how the antifreeze is chosen.
  • The pro offers a loop warranty without a pressure test and flush record to back it up.

What you can do yourself

You can clear the yard, mark the planned loop area and keep vehicles off the work site, and you can keep records of the house's heating bills and insulation details. Do not dig or drill in the planned loop area until underground utilities have been located. Drilling, trenching, loop installation, refrigerant work and the heat pump belong to licensed contractors.

Licenses and permits

Geothermal installation is commonly done by licensed HVAC contractors, and drilling or trenching may need separate licensing or registration. Check with your state or local licensing agency for the requirements that apply to your project.

Geothermal heating installation questions

Does the loop field need a lot of land?

It depends on the design. Vertical loops need less surface space and deeper drilling, while horizontal loops need more yard space and trenching. A site survey shows which fits your land.

Will geothermal work in a cold climate?

Ground-source systems are designed for cold climates as well as warm ones, since the ground stays at a steadier temperature than the air. Ask the designer to show the expected performance for your local conditions.

How long does a geothermal system last?

The indoor heat pump has a service life like other heat pumps, and the buried loop is designed for a long life. Ask the installer for the warranty terms on each part and for a maintenance plan.

Can I add geothermal to my existing ductwork?

Often, yes. The ductwork has to be sized and sealed for the new system, and an installer should check it before you commit.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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