Geothermal Borehole Calculator

Geothermal Borehole Calculator

Enter the depth and temperature at various depths of the borehole:

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FAQs

1. How do I calculate what size geothermal I need?

Calculating the size of a geothermal system typically involves considering the heating and cooling requirements of your property, the local climate, and the available land area for the ground loop installation. A professional HVAC contractor can perform a heat load calculation to determine the appropriate size (measured in tons) of the geothermal system needed to meet your specific heating and cooling needs.

2. How deep do you have to dig for geothermal energy?

The depth required for geothermal energy extraction depends on the type of geothermal system being used. For ground source heat pumps, which are the most common residential geothermal systems, the borehole or trench depth typically ranges from 100 to 400 feet (30 to 120 meters).

3. How deep is the borehole for a ground source heat pump?

The depth of the borehole for a ground source heat pump can vary based on factors such as the local geology and the required heating and cooling capacity. Generally, boreholes are drilled to depths between 100 and 400 feet (30 to 120 meters).

4. How many wells are needed for geothermal?

The number of wells needed for a geothermal system depends on the size of the system and the heating/cooling requirements. For a standard residential ground source heat pump, a typical installation may require one to four boreholes.

5. What is the rule of thumb for geothermal wells?

A common rule of thumb for geothermal wells is to have about 150 to 250 feet (45 to 75 meters) of borehole depth per ton of heating and cooling capacity for residential systems.

6. How big a yard do you need for geothermal?

The size of the yard required for a geothermal system depends on the available land area and the type of ground loop system being installed. For a typical residential ground source heat pump, you would need enough space to accommodate the boreholes or trenches and any required setbacks from property lines and structures.

7. How much does it cost to drill a hole for geothermal?

The cost of drilling a borehole for geothermal energy can vary depending on the location, depth, and drilling method. On average, drilling costs can range from $2,500 to $7,500 per borehole.

8. Can you drill a geothermal well anywhere?

Geothermal wells are more feasible in certain locations with suitable geothermal resources, such as areas with hot springs or volcanic activity. However, ground source heat pumps can be installed in many regions, as they rely on stable ground temperatures, rather than direct access to high-temperature geothermal reservoirs.

9. What size of pipe is used for geothermal?

High-density polyethylene (HDPE) pipe is commonly used for geothermal ground loops. The pipe size can vary depending on the specific design requirements, but typical sizes range from 3/4 inch to 1 1/4 inches in diameter.

10. How much pipe is required for a geothermal ground loop?

The length of the pipe required for a geothermal ground loop depends on the size of the system, the climate, and the available land area. A typical residential ground loop may require anywhere from 1,000 to 3,000 feet (300 to 900 meters) of pipe.

11. What is the average depth of a geothermal well?

The average depth of a geothermal well varies depending on the application and location. For ground source heat pumps, typical depths range from 100 to 400 feet (30 to 120 meters).

12. How long should a trench be for a ground source heat pump?

For ground source heat pumps, the length of the trench required depends on factors like the heating/cooling load and the soil properties. Typically, trenches are several hundred feet long for residential installations.

13. What is the lifespan of a geothermal well?

With proper maintenance and care, geothermal wells can have a lifespan of 50 years or more.

14. How long do geothermal wells last?

Geothermal wells are designed to last for several decades. A well-maintained geothermal system can have a service life of 30 to 50 years or more.

15. How many GPM is a geothermal well?

The flow rate (Gallons Per Minute) of a geothermal well varies based on the specific design and requirements of the system. The flow rate is typically determined during the system design phase.

16. How deep is the deepest geothermal well?

As of my last update in September 2021, the deepest geothermal well was drilled in Iceland, reaching a depth of approximately 7.3 kilometers (about 4.5 miles). Keep in mind that drilling depths may have increased since then.

17. How big is a geothermal loop per ton?

The size of the geothermal loop (length of pipe or number of boreholes) required per ton of heating and cooling capacity can vary. A general rule of thumb is around 400 to 600 feet of loop per ton for vertical boreholes and 150 to 250 feet of loop per ton for horizontal trenches.

18. How hot does water need to be for geothermal energy?

For electricity generation using conventional geothermal power plants, water or steam with temperatures around 300°F to 700°F (150°C to 370°C) is required. For ground source heat pumps, which are used for heating and cooling buildings, the ground temperature can be as low as 45°F (7°C) and still be effective.

19. What type of soil is best for geothermal?

The best soil for geothermal installations is one that has good thermal conductivity, as this allows for efficient heat transfer between the ground and the geothermal loop. Soil types with high clay or sand content tend to have better thermal conductivity.

20. Is vertical or horizontal geothermal better?

The choice between vertical and horizontal geothermal installations depends on factors such as available land area and soil conditions. Vertical boreholes are more space-efficient but can be more expensive to install, while horizontal trenches require more land area but are generally less expensive.

21. Is geothermal good for off-grid?

Geothermal energy can be a viable option for off-grid applications, particularly for heating and cooling. Ground source heat pumps can provide consistent and reliable temperature control without the need for grid power.

22. How long does it take for geothermal to pay for itself?

The payback period for a geothermal system depends on several factors, including the initial installation cost, energy prices, and available incentives. In some cases, geothermal systems can pay for themselves in 5 to 10 years through energy savings.

23. What is the tax credit for geothermal energy in 2023?

As of my last update in September 2021, tax credits for geothermal energy systems were available under the federal government's Residential Renewable Energy Tax Credit (26 USC § 25D). However, the availability and terms of tax credits may change over time, so it's essential to check for the most up-to-date information in 2023.

24. Is geothermal HVAC worth it?

Geothermal HVAC systems can be worth it in the long run, especially for homeowners looking for energy efficiency and reduced utility bills. While the upfront costs can be higher than traditional HVAC systems, the energy savings and environmental benefits can make them a worthwhile investment.

25. Can you drive over geothermal wells?

Driving over geothermal wells or ground loops is generally not recommended to avoid damaging the pipes or loop system. Proper placement and protection are essential during installation to prevent accidental damage.

26. Can you use a geothermal well for drinking water?

Geothermal wells used for heating and cooling are typically closed-loop systems, meaning they circulate a fluid (usually water and antifreeze) within the loop. These closed-loop systems are not designed for drinking water purposes.

27. How long does it take to drill a geothermal well?

The time required to drill a geothermal well depends on various factors, such as the depth, geology, and drilling method. It can take several days to a few weeks to drill and complete a geothermal well.

28. Can you use PEX pipe for geothermal?

Yes, PEX (cross-linked polyethylene) pipe is sometimes used for geothermal ground loops, especially in horizontal trench configurations.

29. Do geothermal pipes freeze?

Geothermal pipes that are buried below the frost line are less susceptible to freezing. Ground source heat pumps are designed to prevent freezing within the system by using a mixture of water and antifreeze.

30. Is copper better than plastic for geothermal?

High-density polyethylene (HDPE) plastic pipe is commonly used for geothermal ground loops due to its durability and resistance to corrosion. While copper pipes can also be used, HDPE is generally preferred for its cost-effectiveness and performance.