Frequently Asked Questions

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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 neverexperienced 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.

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.

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.

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