FAQ
Geothermal Heat Pump Systems
What is a heat pump?
A heat pump is a refrigeration circuit that is used to move heat from one location to another. A heat source (air, water or earth) is used to evaporate the refrigerant, a compressor concentrates and moves it to another location and releases it. It’s like an air conditioner that can run in reverse to cool in summer and heat in winter.
What is a Geothermal Heat Pump (GHP)?
It’s a heat pump that uses the constant and favorable temperature of the earth as its heat source/heat sink. Up to 75% of the heat it delivers to the building is renewable energy; therefore the cost of operation is greatly reduced.
Do they deliver the same or greater comfort as a furnace or an air source heat pump?
Greater comfort . . . absolutely. Their heat source is warmer that ambient air in the winter and cooler than ambient air in summer. Because of the warmth of the earth, EarthLinked systems deliver greater warmth in the winter, without sudden blasts of heat like a furnace. In the summer, their longer run cycles and cooler evaporator coils deliver cooler air with greater dehumidification…thus greater comfort.
Can one system provide space heating and cooling for my home and water heating?
Yes. A GHP can deliver space heating/cooling and hot water heating. You can change from one mode to another with a simple flick of the indoor thermostat. Using a desuperheater on the air conditioning cycle, some GHPs can save up to 50% on your water-heating bill by preheating water.
How does a GHP system heat water for my home?
Using a desuperheater, GHPs use waste heat to heat hot water. During the summer, when the system is in the cooling mode, water heating is a free byproduct of the cooling process. In winter, the desuperheater heats a portion of your hot water. Desuperheaters are standard on some units, optional on others.
How much space does a GHP unit require?
The majority of any GHP system is underground. Inside the building, the heat pump unit is much smaller than traditional heating and cooling units. The EarthLinked system is one-half the size of a water based unit because it does not require a water circulating pump and an intermediate heat exchanger. It is one-half the size of an air-source heat pump because it does not have an outside fan coil.
How long will a GHP system last?
GHPs are durable and highly reliable. All components are either buried in the ground or can be located inside the home, which protects them from weather and temperature extremes. The industry considers the useful life of a GHP to be 20 years. Because of its fewer mechanical components, the EarthLinked system can reasonably be expected to exceed that.
How noisy is the GHP unit?
GHPs are very quiet and unobtrusive. They provide a pleasant environment inside and outside of the home. GHPs have no noisy outside fan units.
How safe are GHPs?
GHP systems are fully enclosed, safe and protected. They have no exposed equipment outdoors. GHPs have no flame, flammable fuel, noxious emissions or fuel storage tanks.
Can these systems be used for commercial, industrial, or apartment requirements?
Yes! Many GHP systems are installed using multiple systems. This simplifies zone control and internal thermal load balancing.
What are the advantages to an HVAC dealer?
GHP systems open access to a huge retrofit upgrade market not subject to wide fluctuations in the housing construction market. This creates an opportunity for stable growth. The systems are relatively maintenance-free, requiring only periodic filter changes. This means fewer maintenance and service calls. There is no need for exposed outside equipment, so wear and tear is less.
What types of geothermal heat pumps are available?
There are essentially two types:
- Water based geothermal heat pump units, which include:
1) Open loop units that pump water from the earth or a pond, exchange heat and then dump the water.
2) Closed loop units that circulate a water and antifreeze mixture in a closed plastic loop, extract heat from the earth, exchange that heat into the refrigerant circuit through a heat exchanger, then distribute the heat using the refrigeration circuit.
- Direct geoexchange systems, including the EarthLinked® brand, that directly exchange heat with the earth by placing the refrigerant circuit in direct contact with its heat source for heating and its heat sink for cooling.
Which type of technology can save the most operating cost?
Because the EarthLinked direct method does not consume energy to circulate water; does not have an intermediate heat exchanger from water to the refrigerant; exchanges heat through copper refrigeration tubing; and it uses proprietary EarthLinked refrigerant flow controls, it has proved to be 25% more efficient in field tests.
Which technology is the least obtrusive to install?
Because the direct method has a higher heat differential with the earth and higher efficiency, it uses approximately on-half the length and one-half the diameter bore hole as the closed loop water based unit; and the earth loops can be installed diagonally, so the footprint at the surface is very small and less drilling is needed.
What sets EarthLinked® systems apart from other GHPs?
EarthLinked’s proprietary modulating refrigerant flow controls add efficiency gains and earth loop options that are not possible with other systems. Utility field tests have shown EarthLinked to be up to 25% more efficient than water based units.
Is one type of GHP better suited to one type of building?
Yes. Because of their size and thermal capacity, EarthLinked systems are best suited for 1) heating and cooling residential and small commercial buildings, and 2) large hot water heating users including commercial and institutional applications. Because of their size and thermal capacity, water based units are better suited to large spaces.
Can the system be used to heat water?
Yes. The EarthLinked water heating options include desuperheating (providing "free" hot water in the cooling mode) and integrated "on-demand" for year-round domestic hot water. The unit can also provide hot water for radiant in-floor heating and swimming pools.
Is the EarthLinked system AHRI certified?
Yes. The EarthLinked system is rated according to AHRI (the Air Conditioning, Heating and Refrigeration Institute) Standard 870 for Direct GeoExchange Heat Pumps. The average heating COP is 3.9, with a cooling mode EER of 17. The system is ETL safety listed and qualified under the EPA EnergyStar® program standards.
What important factors should be considered in the selection of a geothermal heat pump brand?
The product should have:
- At least ten years of field experience in diverse regions;
- Multiple independent verifications of performance;
- Performance rating and safety listing by the Air Conditioning, Heating and Refrigeration Institute (AHRI);
- A history of pioneering innovations in the technology to demonstrate its depth of expertise;
- The ability to provide specific solutions to meet your needs;
- High efficiency ratings;
- An installing dealer network that is available to service your system.
Are the EarthLinked units that are sold in Europe different from those sold in the U.S.?
Yes. The compressors are suitable for 50 Hertz electrical supply and are compatible with Refrigerant R-407C. A larger percentage of the systems sold in Europe are for heating-only because of a cooler climate.
Efficiency / Savings / Costs
How efficient is a GHP?
A GHP is one of the most efficient residential heating and cooling systems available today, with heating efficiencies 40 to 60% higher than other heating and cooling systems. That directly translates into savings on your utility bills and reduced emissions.
Why is a GHP better than an air-source heat pump?
Because of the density of the earth and the water stored within it, the earth is able store tremendous quantities of heat from the sun. In nature, few substances have a higher "specific heat capacity," making it an ideal heat storage medium.
Air, on the other hand has a very low specific heat capacity. It would be necessary to move 3,472 cubic feet of air across the heat exchanger of an air-source heat pump in order to expose that heat exchanger to the same quantity of heat that is stored in a cubic foot of water (7-1/2 gallons).
How will I save money with a GHP?
EarthLinked systems save money, both in operating costs and maintenance costs. Investments can be recovered in as little as three years. There is a positive cash return, since the monthly energy savings exceed the amortized cost of the system.
How much does an EarthLinked GHP cost?
The initial investment for a GHP system is greater than that of a conventional system because of the need to couple with the earth. However, when you consider the operating costs of a heating, cooling and water heating system, energy savings quickly offset the initial difference in installed cost.
What creates the unique value in an EarthLinked system?
High efficiency results in lower operating costs. Engineered simplicity with fewer components results in a smaller unit that is more reliable and requires very little maintenance. It is also quiet and unobtrusive.
How do the cost and savings of solar and wind systems compare with EarthLinked systems?
Solar systems may have an installed cost approximating that of an EarthLinked system, but wind energy systems are more expensive. The operation of solar and wind systems is intermittent, so the cost recovery period is substantially higher than that of an EarthLinked system that can operate every hours of the year.
Installation
Are EarthLinked GHP systems difficult to install?
Systems are not difficult to install in most locations, especially when replacing another forced-air system. EarthLinked systems can be installed in areas unsuitable for fossil fuel furnaces because there is no combustion and thus no need to vent exhaust fumes. Ductwork must be installed in homes that do not have an existing air distribution system. An installer can assess the cost of installing ductwork.
Can I install a system myself?
No. Drilling, trenching and refrigeration service are procedures best handled by licensed professionals.
What about installation and maintenance?
Because the EarthLinked unit has fewer components, it is smaller and simpler. Thus it is easier to install, requires less maintenance and is more reliable than geothermal systems that circulate water.
What is the size of the earth loops?
EarthLinked systems use up to 150 linear feet of copper refrigeration tubing per ton (12,000 BTUs) of heat pump capacity and are installed in a 3” diameter hole. Water based GHPs generally use 250 feet of plastic tubing per ton of capacity and are installed in a 4-6” diameter hole.
How is the earth loop system installed?
EarthLinked’s DIRECT AXXESS® earth loops can be installed horizontally in pits or trenches using excavators or trenchers, as well as vertically or diagonally using small bore drilling equipment. Water based systems generally use larger well-drilling equipment.
How long does it take to install the earth loops?
Loops for a 3-ton system in pits and trenches can often be installed in a single day. Loops using vertical and diagonal bores can be installed in two days.
What special training is required for installation?
System start-up does not require a purging cart, the addition of antifreeze, or other tasks associated with water loop systems. On the refrigerant side, factory-assembled earth loops are soldered to pre-fabricated manifolds, and visual indicators assist in system charging (no charging charts needed). Thus, little special training is required for experienced heat pump technicians.
How long have EarthLinked systems been operating?
In 1980, EarthLinked Technologies, Inc. (ETI) began research and development of EarthLinked systems. In 1985, field demonstrations began for ten electric utilities from Florida to Michigan. Marketing commenced in 1995.
Can I replace an existing air source heat pump with an EarthLinked system?
Yes. Existing ducting and air handlers can be used with minor modifications if they are in good condition and are appropriately sized. Earth loops and the compressor unit must be added.
How long will the earth loops last?
Copper is one of the few metals that exist naturally as an element in the earth. A noble metal, it naturally resists corrosion in most underground environments because of the protective film that forms naturally on its surface. In rare exceptions where pH readings exceed safe levels, cathodic protection for the in-ground copper is offered by ETI. With some installations dating back to 1980, ETI has never experienced a field failure of a production earth loop due to corrosion.
How does the Cathodic Protection System work?
ETI consulted with multiple experts, including a university professor who has a PhD in metallurgy and is a Professional Engineer, to determine the best method of precluding corrosion in harsh environments. A comprehensive study resulted in the creation of the Cathodic Protection System (CPS).
Copper buried in the earth naturally resists corrosion because it generates a self-protective negative voltage potential relative to the surrounding soil. In those rare areas where corrosive conditions may reduce or eliminate this self-protective voltage, corrosion can be prevented with a small amount of “impressed electrical current” applied to the copper through a buried inert metal or graphite anode.
The CPS control system uses the Impressed Current method. It supplies a specific number of milliamps per square foot of copper that is in contact with the earth. It constantly delivers direct current to the earth loops, manifolds, and line sets. The amount of current is pre-set at the factory to match the amount of copper to be protected. As current flows from the CPS, the metal surface is given a uniform negative electrical potential that precludes corrosion.
Click to learn more about
the CPS and copper in the ground.
How do the earth loops work?
The standard compressor circulates refrigerant through the earth loops (with sufficient velocity to transport the lubricating oil through the system) while it is heating in the winter or reversing the flow for cooling in the summer. Its patented refrigerant flow controls assure a flooded evaporator condition and full utilization of the condenser for optimum efficiency under all operating conditions.
How do ETI's Adaptiv™ Refrigerant Flow Controls differ from others?
The two controls are simple mechanical controls that respond directly to the temperature and velocity of refrigerant flow through the system. They modulate the amount of refrigerant in circulation to assure optimum efficiency at all times. By eliminating subcooling in the condenser, the system operates at lower refrigerant "head" pressures with increased mass flow, which reduces energy consumption and increases heat transfer system reliability and useful life.
Is a two-speed compressor feasible with an EarthLinked system?
No. The velocity of the refrigerant that circulates for heat exchange in the earth loops is crucial because it must maintain a sufficient rate of circulation to continuously transport the compressor lubricating oil. A two-speed compressor could reduce the velocity to the extent that oil would not be returned to the compressor, which would be detrimental to the unit.
Where is the compressor unit installed?
Because the EarthLinked system does not require an outdoor coil and fan, the compressor unit can be located in a basement, utility room, garage or outdoors. A fully enclosed, well insulated cabinet assures quiet operation.
Click to see a geothermal installation process.
Will my existing ductwork function with this system?
Yes, in most cases. Your installer will be able to determine ductwork requirements and whether any modifications are needed.
Will an underground loop affect my lawn or landscape?
No. Loops have no adverse effects on grass, trees, or shrubs. Most horizontal installations are in place before landscaping is added. Temporary bare areas can be restored with grass seed or sod. Diagonal loops require very little space and temporarily affect only a small area at the surface. To avoid disturbance by tree roots, the manifold should not be located near a tree.
Can a GHP system be added to my fossil fuel furnace?
They can be added to a home with an existing furnace for a dual-fuel heating system. Dual-fuel systems use the EarthLinked system as the money-saving main heating source, and a fossil fuel furnace as a supplement in extremely cold weather, if additional heat is needed.
Environmental / Climate
What is "clean technology"?
Clean technology is any product or service that creates value by using renewable resources, uses less or no non-renewable resource and creates little waste.
What is "energy efficiency"?
Energy efficiency refers to using less non-renewable energy to achieve the same level of service. It does not mean sacrificing the quality of service. For example, using less energy to deliver the same or greater level of comfort.
What is “Energy-as-a-Resource”?
Energy efficiency is the cheapest, cleanest and most readily available energy resource. Reduced energy consumption reduces the need to purchase and transport non-renewable fuels to generate electricity and additional generation, transmission and distribution capacity.
What is environmentally friendly heating and cooling?
Environmentally friendly heating and cooling is that which has the least harmful effect on the environment, such as the use of renewable energy from the sun, wind or heat from the earth.
What are direct use and indirect use of geothermal energy?
Geothermal energy is heat from the earth. High temperature steam is derived ultimately from the core of the earth and is used for district heating, industrial purposes and to turn turbines that generate electricity. Low temperature geothermal energy results from the sun heating the shallow earth daily. That is the heat source for geothermal heat pumps.
How do EarthLinked GHPs protect the environment?
GHP systems conserve natural resources by providing high efficiency climate control using indigenous renewable energy, thereby lowering the consumption of fossil fuels and the resulting emissions that contribute to climate change and acid rain.
Does freezing of the soil create a problem for the EarthLinked system?
No. EarthLinked ground loops are buried below the frost line and they do not circulate water, so freezing is not an issue. The sun continues to warm the earth year-round. Although EarthLinked has proven that it can effectively extract heat through ice, the earth loops and manifold are buried below the freeze line.
In extremely cold climates, is an additional heat source necessary?
All heating systems should have an emergency back-up in extremely cold climates. EarthLinked heat pumps can provide all of the heat necessary, even in the coldest weather. They operate efficiently from Miami to Montreal, and Australia to Estonia. An economic analysis by your contractor should determine what portion of the heat should be provided by the heat pump and what portion by auxiliary means. It is sometimes best to rely on supplemental heat on the few coldest days and thus reduce the capacity and installation cost of the heat pump.
Are EarthLinked systems limited by hot or cold climates?
No, they operate efficiently in extreme northern or southern locations. They can extract heat from very cold soil and reject heat into warm soil because:
- They have a high temperature differential with the soil due to their direct exchange characteristic; and
- The proprietary refrigerant flow controls cause the system to operate efficiently throughout the entire range of thermal loading, due to their modulating capability.
Is there independent proof of the effect EarthLinked systems have on the environment?
U.S. EPA and DOE have determined that ground source heat pumps have the lowest environmental impact of all heating systems and they reduce energy consumption and corresponding emissions up to 72% when compared to electric heat strips and standard air conditioning. The refrigerant used by EarthLinked is not toxic, and is the same as that currently used by a majority of the HVAC industry. The system’s efficiency results in greatly reduced emission of greenhouse gases and toxic gases associated with fossil fuel firing and the generation of electricity.
Commercial Water Heating
What type of customer is the system designed to serve?
Large users of hot water, including lodging, healthcare, multi-family dwellings, institutions, food processing and service, laundries, cold weather car washes and swimming pool heating.
What is the operating history of EarthLinked water heating?
EarthLinked Technologies began the development of the system in the 1970s. Independent verification of its unequalled efficiency was obtained at the Florida Solar Energy Center in 1984 and the U.S. EPA confirmed the same 75% savings in the commercial water heating application in 2006.
How much water can the system heat in each day?
The system can deliver 2,500 gallons per day at 120°F.
How can I control the water temperature?
The EarthLinked system delivers pre-heated water to your standard water heater where it is stored and the temperature can be raised. A standard aquastat in that tank maintains temperature control.
How much can it save in operating costs?
Please click to see the Cost Comparison page on this website.
What about greenhouse gas emissions?
Field testing by U.S. EPA verified up to 75% energy savings and avoidance of the emission of up to 7,000 pounds of CO2 and 50 pounds of NOx per ton of heat pump capacity each year as compared to electric resistance water heating (up to 42,000 pounds of CO2 and 300 pounds of NOx each year by a 6-ton system).
How much space do the earth loops require?
Diagonal earth loops disturb only a radius of approximately six feet during installation where the earth loops converge.
How much space does the heat pump unit require inside the building?
The heat pump and refrigerant-to-water heat exchanger are in a single small unit that is 17”D x 24”W x 26”H.
Does it need to circulate air?
No. The compressor unit does not circulate outside air to deliver heat to the water heater tank.
Is it noisy?
No. Without the need to circulate air, the unit is fully enclosed and insulated. The only moving part is the standard heat pump compressor that is inside the enclosed unit.
What about reliability?
Because the system delivers pre-heated water to a standard water heater, either electric or gas, it increases the reliability of the water heating system. The existing water heater is no longer subjected to a wide range of temperatures and serves only to “top off” the temperature and store the water, thus it operates for a limited time and is more reliable.
