Geothermal Ground Loop FAQs

Geothermal Ground Loop FAQs

Curious what makes a geothermal heating and cooling system so remarkably energy efficient? It’s the ground loop!

Not sure what that is? You’re about to learn everything you need to know.

Read on for the answers to our most frequently asked questions about geothermal ground loops.

What Is a Ground Loop?

A geothermal system’s ground loop consists of a network of fluid-filled pipes buried beneath the surface of the earth.

The ground loop is buried at a depth where subsurface temperatures remain relatively constant year round. This consistent subsurface temperature allows the thermally conductive fluid within the ground loop to transfer heat energy into and out of the earth.

How Does a Ground Loop Operate?

The ground loop contains an antifreeze-water solution that’s capable of both extracting heat from the earth and depositing heat into the earth. A pump continually circulates that solution through the ground loop’s network of pipes and into the geothermal heat pump, which captures the heat energy carried by the fluid.

When the thermostat is set to heat the home, the antifreeze solution absorbs heat energy from beneath the surface of the earth. The fluid carries that heat to the heat pump, where the heat exchanger uses it to warm the interior of the home.

When the thermostat is set to cool the home, the process reverses. The geothermal system draws heat from the air inside the home, transfers it to the thermally conductive fluid inside the ground loop, and the fluid deposits that heat energy into the earth.

Want a more in-depth breakdown? Check out Everything You Need to Know About Geothermal.

Does a Ground Loop Handle Both Heating and Cooling?

Yes, when a home has a geothermal system installed, the ground loop — in conjunction with the heat pump and heat exchanger — is responsible for both heating and cooling the home.

Check out Does Geothermal Heating Really Work in Cold Climates for more info.

What Is a Horizontal Ground Loop?

A horizontal ground loop is a network of underground pipes that are buried over a wide area and connect to the geothermal heat pump inside the home.

Some geothermal companies put the horizontal ground loop field in trenches. These trenches are dug by an excavator at 8-10 feet and are 100-400 feet long. We have found that this is not only considerable work, but after installation the customer is left with a yard that needs quite a bit of reseeding or sodding.

Our company specializes in the horizontal ground loop, but we use a trenchless technology known as directional drilling to insert the ground loops into the earth horizontally with minimal ground disturbance. It is faster and cleaner.

What Is a Vertical Ground Loop?

A vertical ground loop typically consists of two small-diameter boreholes that range from 100 to 400 feet deep, buried about 20 feet apart.

The holes are typically five to six inches in diameter and contain piping that connects in a U-bend at the bottom of the boreholes. The vertical pipes connect to shorter horizontal pipes that attach to the geothermal heat pump located in the home.

Generally, vertical ground loops are more expensive to install than horizontal ground loops because of the depth of drilling required. This type of loop is common in urban areas that lack sufficient open land for digging horizontal ground loop trenches.

What’s the Difference Between a Closed-Loop and Open-Loop Geothermal System?

A closed-loop system features a sealed, continuous ground loop that circulates thermally conductive fluid, which transfers heat out of and into the earth. An open-loop system doesn’t use the heat contained within the earth; instead, it uses heat energy from a nearby water source.

The open loop pulls water from a nearby pond or well and runs that water through a heat exchanger inside the heat pump. Once the heat exchanger extracts the heat from the water, the system expels the water and deposits it back into the pond, a drainage ditch, or a well, depending on local code requirements.

Open-loop systems aren’t super common. However, because groundwater also remains at a relatively constant temperature year round, it’s also an excellent source of heat energy. When groundwater is readily available or the property owner has a pond, an open-loop system can be a cost-effective alternative to a closed-loop system.

How Do You Determine What Size Ground Loop My Home Needs?

We size your ground loop based on the size of heat pump your home requires, the climate in your area, and the soil conditions on your property.

During your geothermal consultation, we’ll perform a Manual J Load calculation, which allows us to determine your home’s heating and cooling needs. Basically, the larger your home’s heating and cooling load is, the larger your heat pump will need to be, and therefore, the larger your ground loop will also be.

How Long Does a Ground Loop Last?

Geothermal ground loops typically last upward of 50 years with minimal maintenance and some last as long as 100. Their remarkably long functional life allows homeowners to save a substantial amount of money on heating and cooling costs over many, many years.

Aside from energy cost savings, geothermal systems offer several other perks, too! To learn all about them, check out The Benefits of Switching to Geothermal.

What Will a Ground Loop Do to My Lawn or Landscaping?

The ground loop installation process will disrupt the surface of your lawn to some degree. During the planning process, we evaluate the site extensively, assessing both its surface and subsurface geology. We then take the necessary measures to mitigate sediment and dust and minimize surface disruption as much as possible.

Immediately after installation, you’ll be able to see where we drilled to install the loop. However, with proper restoration—which may involve a small amount of sodding or reseeding of any disturbed areas—the loop field will become virtually undetectable over time.

After installation, the loop itself shouldn’t impact your landscaping at all.

Can I Plant Trees Directly Over a Ground Loop?

Yes, you can plant trees over the area where the ground loop sits. But doing so may not be in the best interest of the trees.

That’s because:

  • Root systems may grow into the ground loop area. If the loop needs repairs or additions at any point, the tree may suffer considerable damage.
  • The soil around the pipes could freeze. The temperature of the thermally conductive fluid inside the pipes can get very low. If it gets low enough that the surrounding soil freezes, any tree roots in the area could suffer.

If you want to plant trees after your loop installation is complete, ask your geothermal installer where you should put them to prevent root damage.

Can a Ground Loop Be Installed Under or Near a Septic System?

That depends on regulations in your area. Generally, it’s not recommended and is actually prohibited in many places. Your area’s code will specify the minimum degree of separation between loop piping and sources of pollution (drain fields, septic tanks, etc.) and water supply wells.

While installing a geothermal ground loop under or near your septic system might seem like a good idea to help boost the thermal conductivity of the loop, it could cause problems. When a ground loop extracts heat from the earth or deposits heat into the earth, the temperature of the ground around the loop changes.

Those temperature fluctuations can affect the bacteria and enzymes that break down solid waste and are a crucial part of any septic system’s waste disposal process. If the temperature gets too high or too low, it can cause bacterial dieoff or overgrowth. Either situation can alter the balance of the ecosystem within the tank and drainage field.

Ultimately, changes in that ecosystem can result in a buildup of solids in the tank or disturbances to the biomat in the drain field. When that happens, you could wind up with a failed septic system that requires costly repairs.

Get a Geothermal System Consultation for Your Home!

Ready to learn more about geothermal heating and cooling and whether it’s the right choice for your home? Schedule a consultation with our team at The Comfort Company!

We specialize in full-service geothermal system installation for homes throughout Minnesota and northwestern Wisconsin. Call us today at 218-231-4436 or send us a message to get started!