We understand Geothermal Systems may be confusing, so we collected the most frequently asked questions and answered them for you.
What is Geothermal Energy?
The use of geothermal energy is becoming a popular trend now, more than ever before. The word geothermal comes from “Geo” (earth) and Thermal (heat). Very simply put geothermal is heat from the earth, but what you may not know is that there are 3 grades or temperature ranges of geothermal energy.
- High Grade Geothermal falls into a temperature range greater than 300⁰F
- Medium Grade Geothermal falls into a temperature range of 140⁰F – 300⁰F
- Low Grade Geothermal falls into a temperature range of 50⁰F – 65⁰F (available to anyone in the world)
High-grade Geothermal Energy (greater than 300⁰F) is when temperature of the earth’s is so hot that it heats up water below core pressure that turns water into steam. This energy is released in the form of steam from geysers like Old Faithful in Yellowstone National Park. There are currently about 20 locations that utilize this type of geothermal energy to produce electricity. These sites can produce electricity for approx 5-8 cents per kw/hr.
Medium-grade Geothermal Energy (140⁰F – 300⁰F) Underground wells and springs in some parts of the world can provide hot enough water to be utilized directly for heating your home. The Hot water that comes from the ground can be piped to run directly through radiators to effectively heat an indoor space. Some Rocky Mountain areas and West Coast States have greenhouses that use medium grade geothermal energy to heat with.
Low-grade Geothermal Energy (50⁰F – 65⁰F) is the heat within the earth’s crust. This heat is actually stored solar energy and is used in commercial and residential geothermal applications.
What’s a geothermal heat pump?
A heat pump is a mechanical device used for heating and cooling which operates on the principle that heat can be moved from a warmer temperature source to a cooler temperature source. A Geothermal System is a type of heat pump often referred to as a Ground Source Heat Pump that uses the earth to warm us in the winter and cool us in the summer. You may not know it, but you most likely already have a heat pump in your home – your refrigerator. The same method your household refrigerator uses to cool your food is the same method a geothermal uses to cool your home. If you put your hand in front of the grill at the bottom of your refrigerator you will feel the heat that has been removed from the food inside the refrigerator. This is the same principle that a geothermal heat pumps use to heat and cool your home.
Ok, geothermal can heat my home, but can it cool it, too?
Yes, one of the reasons a geothermal heat pump is so versatile and efficient is its ability to heat and cool as one system. With the press of a button on your indoor thermostat the geothermal heat pump changes from the heating mode to the cooling mode.
How does the heat from the ground get into my home?
This process takes place through the ground loop. There are two lines that connect the outside ground loop to the unit inside the home. In one line there is a fluid that flows out into the ground loop and absorbs the heat from the ground. This fluid (water or refrigerant) then returns back to the unit through the second line in which it enters into the geothermal system, where the heat is extracted from the water or refrigerant and used to heat the home. In the final step, the heat is transferred into the air and blown throughout your home.
Can I replace my standard geothermal plastic ground loop with a copper ground loop?
This question is a popular question because often the expected savings of a standard water geothermal does not meet the client’s expectations, or they have higher electric bills than they estimated. Due to the cost of running the backup heat. Unfortunately, the answer is NO, we cannot install a copper ground loop on a standard water geothermal because a water geo is designed to pump water through the ground loop. And the copper ground loop of a direct exchange (DX) geothermal is designed to only pump refrigerant through the copper tubing.
What is the fluid in the pipes and is it safe?
There are also two types of fluids that can be used to circulate through the ground loop system. They are refrigerant, or a water and antifreeze solution (propylene glycol).
A standard water geothermal unit uses a water and antifreeze solution, while a DX geothermal design uses an EPA approved, environmentally friendly refrigerant (freon) that circulates through the copper ground loop. The geothermal unit and the ground loop both contain a heat exchange fluid. All geothermal systems operate using refrigerant (freon) as one of the fluids that circulate through the indoor unit. As stated by the EPA, “Refrigerant is also a non toxic, inert gas, posing no direct health threat to humans – nor to ground water – and it can be used with confidence in underground heat exchangers as part of a DX System.” The use of refrigerant has been used for more than 50 years. It is so safe that the food we get from the grocery store is kept in a cooler that uses refrigerant. Food remains safe to consume even after it has been exposed to refrigerant leaks.
What’s an open loop system?
An open-loop system is typically considered less frequently in new construction, but may be more cost-effective if groundwater is plentiful. Open-loop systems in fact, are the simplest to install and have been used successfully for decades in areas where local codes permit. This type of system uses groundwater from a water well aquifer and is piped directly from the well to the house, where it transfers heat from the well water to the house.
After the heat is removed from the water, it is disposed by one of two methods:
- Surface drainage – to a low area such as a pond, river, lake or stream, etc.
- Subsurface – to a dedicated field drain, sized to handle the volume of water of the geo unit.
How much groundwater does an open loop need?
An open loop geothermal system needs different amounts of water depending on the size of the unit and the manufacturer’s specifications. The water requirement of a specific model is usually expressed in gallons per minute (g.p.m.) and is listed in the specifications for that unit. Your water well and heat pump combination should be large enough to supply the water needed by the geothermal heat pump, in addition to your domestic water requirements. The geothermal heat pump requires approximately 2 to 12 gallons of water per minute.
Can poor water quality affect a geothermal system?
Poor water quality will cause serious problems in open-loop applications. Water can cause mineral deposits to build up inside the heat pump heat exchanger and periodic cleaning will be required. Water from flowing springs, ponds, lakes or river sources are not recommended for heat pump use, unless proven to be free of excessive particulate and organic matter. These sediments will contaminate the heat exchanger heat pump system and make it inoperable.
Does a standard open loop system cause environmental damage?
No, the heat pump only moves heat from one source to another, therefore no pollution is generated. The only change in the water after it’s used by the heat pump is a slight increase or decrease in temperature. However, the high volume of water being wasted each year (approximately 1 million gallons) is something you may want to consider.
Are there any laws that apply to a standard geothermal open loop system?
In some locations, all or parts of the installation may be subject to local ordinances, codes, covenants or licensing requirements. Check with local authorities to determine if any restrictions apply in your area.
What’s a geothermal closed loop system?
A geothermal system in which the ground loop uses a continuous loop. A predetermined amount of fluid is circulated repeatedly throughout the system. There are many methods used to bury a closed loop system in the ground.
Below are some of the more popular closed loop geothermal designs:
- Horizontal Closed Loop – DX Geothermal
- Vertical Closed Loop – DX Geothermal
- Horizontal Closed Loop – Water Source Geothermal
- Horizontal Slinky Closed Loop – Water Source Geothermal
- Horizontal Directional Bore Closed Loop – Water Source Geothermal
- Vertical Closed Loop – Water Source Geothermal
- Pond Closed Loop – Water Source Geothermal
Can a geothermal heat pump system heat my water?
Domestic hot water is available with the use of a heat pump for pennies a day. It can even be free. A hot water desuperheater is a heat exchanger built into the geothermal system and is designed to remove high temperature heat from the refrigerant and is used to supply domestic hot water. A typical hot water desuperheater will generally provide 120° F water and can supply most of the domestic water needs depending on the amount of consumption.
Do I need to increase my electrical service?
Most homes already have adequate electrical service. Check with your contractor to verify that your electrical service is adequate to operate a Geothermal System.
Where is the geothermal unit installed?
Most geothermal units are located indoors in a utility room, garage, or basement. This is very appealing for many reasons. Indoor installations free up outdoor space allowing better architectural design and yard usage. Noise normally associated with outdoor condensers is eliminated and because the electrical controls and heat exchanger coils are protected from the outdoor elements this then allows greater system longevity.
I have a large house. Will your systems provide enough heat throughout my home?
Yes, the best practices of designing a geothermal recommends that you do a “Manual J” computerized heat load calculation for every geothermal installation to insure that the system is designed properly for your home.
How do Geothermal Systems compare to conventional heating and cooling systems?
Although geothermal systems have higher upfront cost to install over a conventional heating and cooling system, the lower energy cost to operate a geothermal system adds up very quickly to a large annual savings, resulting in a three to eight year payback on your investment.
Will this system add value to my home?
Yes! Home Appraisers and Real-estate Agents are educated and acknowledge a Geothermal System as a renewable energy source with greater value. Installing a geothermal system will definitely increase the value of your home.
Is it true that Geothermal Heat pumps are good for the environment?
Yes, a conventional fossil fuel furnace generates heat by burning fossil fuels that release pollutants into the environment. Geothermal heat pumps generate heat by simply moving the heat from one place to another. In addition only a fraction of the energy is consumed by the geothermal system, it therefore has a very low impact on the environment.
Geothermal Resource Center
Want to learn more about Geothermal energy and how it works? Our resource center has all the information you need!Visit the resource center