Geothermal Heat Pumps

Ground Source Heat pump ground loop diagram showing horizontal and vertical well layouts

How They Work

Geothermal, or ground source heat pumps (GSHP), are electric appliances that provide heating and cooling by moving heat into a building (for heating) or out of a building (for cooling). Heat pumps do not create heat through burning fossil fuels or through electric resistance like conventional heating systems.

Instead, they transfer heat from one place to another by using a refrigerant and heat exchanger that absorbs heat from one place and releases it into another. This is similar to the way that a refrigerator or air conditioner works except that heat pumps can move heat in either direction to provide heating or cooling.

Geothermal heat pumps differ from air source heat pumps in that they use heat from the ground (as opposed to the outdoor air). They use piping and water underground to exchange heat and an indoor heat pump unit to take heat from the water and distribute it throughout your building.

Since the ground maintains a more stable year-round compared to the outdoor air, geothermal heat pumps are more efficient than air source heat pumps, offering heating efficiencies of 350-500+% compared to 80-90% for fossil fuels and <100% for traditional electric resistance heat while also exceeding the efficiency of central air conditioners.

What Makes a Geothermal System a Good Fit for my Needs?

If you answer yes to one of these questions, you could be a good candidate for geothermal. 

  • Do you heat with oil, propane or electric resistance and want to reduce your heating bill?
  • Do you have an existing heating or AC system that is 15+ years old?
  • Do you have yard space that could accommodate drilling or excavation?
  • Are you expecting to live in your home for at least 5 more years?
  • Is someone in your household sensitive to air pollutants or allergens?
  • Do you want to greatly reduce carbon footprint?
  • Are you concerned about outdoor aesthetics or damage to outdoor equipment?
  • Are you considering a new construction project?

Types of Geothermal Heat Pumps

There is a wide range of geothermal system models and configurations that can match the needs of your building. The most common options for the outdoor (ground loop) and indoor configurations are discussed below:

Ground Loop

The ground loop serves as the heat exchange surface for your heat pump where heat is absorbed from or transferred into the ground. A home will typically need several hundred to a thousand feet of piping in the ground loop to provide enough heat in the coldest part of the year. Most ground loops are divided into “closed” and “open” loops:

  • Closed loop systems are the most common option used in New York State, using piping buried into the ground that circulates a mixture of water and environmentally-friendly antifreeze for heat transfer. This heat transfer fluid is not directly exposed to the environment, and the piping itself is typically made out of high-density polyethylene (HDPE) and is warrantied against leaks for decades. Closed loop systems can be installed vertically, where piping is run through multiple boreholes drilled several hundred feet into the ground, or horizontally where piping is run through multiple trenches approximately 6 feet deep and several hundred feet long.
  • Open loop systems can be installed where there is an available source of groundwater available on the property from a well. Instead of circulating an antifreeze mixture, an open loop system will pump groundwater into the heat pump unit indoors to extract heat before being safely returned to the ground. Open loop systems are typically cheaper to install and more efficient (due to the more consistent year-round temperature of groundwater), though they require additional pumping energy, a readily-available source of clean groundwater, and may require additional permitting or environmental review.
Diagrams of vertical closed loop, horizontal closed loop, and standing column well (open loop) geothermal systems

From left to right: diagrams of (1) vertical closed loop, (2) horizontal closed loop, and (3) standing column well (open loop) geothermal systems.

Other options are available depending on your site: for example, if you have a large pond on your property, you could install a closed loop system using the pond water for heat transfer!

Indoor Unit

Geothermal systems also have an indoor heat pump unit that transfers heat out of or into the ground loop. The most common options are "water-to-air" or "water-to-water," selected based on the way your building distributes heat.

  • Water-to-air heat pumps are connected to a central air handler and use your home’s existing ductwork to distribute heating and cooling throughout the home. Some changes to your building's ductwork may be necessary to make it suitable for a geothermal system.
  • Water-to-water heat pumps are connected to your existing hot water distribution system to provide heating. Note that the temperature of water efficiently heated by a GSHP is lower than that required for higher temperature hot water distribution systems (e.g. most radiators and some hot water baseboards), so replacement of existing radiators may be necessary. An air handler/ductwork or a chilled water system would be needed to provide cooling.

Frequently Asked Questions

What are the benefits of installing geothermal?

Energy savings. Geothermal heat pumps are the most efficient heating and cooling system available—even more efficient than air source heat pumps. If you currently heat with oil, propane, or electric resistance heat, you could save hundreds to thousands of dollars a year on your heating bill by installing a geothermal heat pump. No need to pay thousands of dollars just to get a gas connection to your home: a cleaner, more efficient alternative is already available.

A clean, whole-home solution. Geothermal can offer a clean whole-home heating and cooling solution without requiring backup heating. Eliminate fossil fuel combustion and associated risks (such as carbon monoxide poisoning) from your home entirely. Geothermal can also heat 40-100% of your home’s hot water at no additional operating cost with a standalone unit or an add-on desuperheater.

Greatly reduce your carbon footprint. As the most efficient heating and cooling technology available, geothermal heat pumps will greatly reduce your carbon footprint and dependence on fossil fuels. Using solar photovoltaic (PV) panels or other renewable electricity sources can further offset emissions from the electricity powering your heat pump. If you’re looking for the most environmentally-friendly heating and cooling system available, look no further.

Improved home comfort and health. In addition to providing cooling, heat pumps filter and dehumidify air, which can improve the air quality and comfort of your home. In particular, the filtration can significantly reduce allergens in your home for sensitive individuals. Geothermal systems have room for a variety of optional air quality improving devices, including electrostatic filters, UV filters, humidifiers, and heat recovery ventilators, as well as the ability to add heating and cooling zones to your home to enable you to control the temperature in different parts of your home.

No exposed outdoor components. If you are concerned about the aesthetics of outdoor equipment or its exposure to the elements, all outdoor components of a geothermal system will be buried underground (compared to central air conditioners and air source heat pumps).

What are some drawbacks of geothermal?

High upfront costs. GSHPs are expensive to install, with most systems costing around $20,000 after incentives to install. While their significant energy savings pay for themselves, they can take several years to pay back the difference compared to traditional fossil fuel or central AC systems.

Installation time. As system design, incentive approval, and drilling/excavation is required, the geothermal installation process can take several weeks to complete. If you need a heating or cooling system replacement quickly, a GSHP system may not be well-suited for an emergency replacement. However, this depends on your installer; some can do quick installations. 

Landscaping considerations. GSHP systems do require drilling or excavation in your yard. Vertical loop systems require less disruption to your property than horizontal, though there will still be some disturbance associated with the drilling process and moving drilling equipment around. Ask your installer about your options for minimizing disruptions and restoring landscaping after installation.

Ductwork installation or modification may be required. Geothermal systems can offer both heating and cooling, but there can be some limitations to what existing distribution systems a geothermal system will work with. While geothermal heat pumps can work with low-temperature hot water distribution systems (like radiant floor heating and some baseboards), they are not able to provide enough heat for steam or more common high-temperature water heating systems (like radiators). Ductwork may need to be added for your geothermal system to provide cooling, though even if you already have ducts, some modifications may be necessary to adapt your ductwork from being designed for furnaces to being designed for geothermal.

How much yard space do I need to install geothermal?

While a horizontal system will require a few hundred square feet of yard space, a vertical closed-loop system will require only a few small boreholes. These boreholes typically need to be drilled 10-15 feet away from the foundation and spaced approximately 15 feet apart (with some homes only needing a single borehole). For vertical systems, a larger consideration will be whether the drilling rig will be able to fit into the area where the boreholes will be drilled.

When you get a free site visit from one of our installers, they will assess not only the suitability of your home and where boreholes or trenching could be located, but whether all necessary equipment will fit onto your property.

Do geothermal heat pumps work in winter? Geothermal heat pumps function very well during winter, as the earth maintains a more consistent temperature throughout the winter than does the air. As a result, geothermal heat pumps will perform better than air source heat pumps during the coldest parts of winter and can serve as the sole source of heating year-round, even during the coldest parts of the year. In addition, GSHP systems are not exposed to outdoor weather and thus do not need to perform more inefficient defrost cycles as with ASHP systems.
Are there cost differences between the various well types?

Horizontal systems tend to be the cheapest due to the lower cost of excavation compared to drilling. Open loop systems (standing column wells) are generally cheaper than vertical closed loop systems because less drilling is needed for a system of the same size. While standing column well systems can be cheaper upfront, they also have the added cost of a submersible pump and power line—and because the pump needs to pump water up hundreds of feet, the pump will use more energy and need to be replaced more frequently than a closed loop pump.

Costs can also differ from project to project depending on the geology of your site. Ask your installer for more information on the different loop configurations that could work for your building.

How much could I save with geothermal?

Under average energy prices from the last 5 years in the Central New York region, a geothermal system could provide up to 75% savings for homes heated with electric resistance or propane and up to 55% savings for homes heated with oil. Homes that heat with gas would see some energy savings, though it would not be sufficient to offset the higher cost of a geothermal system, particularly given the relatively low current cost of gas.

While every home is different and has different energy needs, typical costs to provide the same amount of heat by fuel/system type (measured in millions of Btus) are provided in the image below.

heat pump estimated operating costs

Your actual annual energy savings will vary based on a number of factors. For example,energy prices—particularly fossil fuel prices—fluctuate from year to year. Your savings over the lifetime of the system will depend on how future costs of electricity change relative to the costs of the fuel you currently heat with.

Additionally, different models of heat pumps vary in efficiency, with variable speed systems in particular being the most efficient (though higher in upfront cost.

Speak with your installer to learn more about how much you could save.

What incentives are available to me

NYSERDA offers an incentive of up to $1,500 per ton of capacity (12,000 Btu/hr) for geothermal. The average incentive received for residential/small-scale geothermal systems in CNY has been nearly $7,000 to date. Your HeatSmart CNY installer will submit the incentive paperwork on your behalf and deduct the value of the incentive from the cost of your system. Click here for more information.

National Grid offers rebates ranging from $200-400 per ton for geothermal, depending on the level of efficiency (~$900-1,800 for a typical residential project in CNY). Click here for more information.

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