TECHNICAL

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| Compare with other Geothermal systems   
| Earth Loop    | Heat Pump
| Geothermal Heating    | Geothermal Cooling    | Design Features   

Compare our system with other Geothermal systems

There are two main geothermal heating & cooling systems available to Australian households - the revolutionary refrigerant-based EarthLinked^® system (of which Energycore is the sole-distributor in Australia), and the more traditional water-loop based systems.

This section contrasts the two models and shows the significant advantages of the EarthLinked^® system.

EARTHLINKED® DIRECT EXCHANGE	CONVENTIONAL CLOSED LOOP (WATER SOURCE)
Uses no water. No Secondary water pump No Additional energy to operate pump. No pump maintenance or replacement.	Uses water/glycol solution. Must have secondary water pump. Stated energy costs are not realistically included in efficiency ratings.
EARTH LOOP DIFFERENCES
No groundwater contamination. No secondary or intermediate heat exchanger. No lost energy in exchange process. Refrigerant in ground coil actually goes through a phase change process, with high energy transfer. Certified coefficiency of 3.5 - 5.0+	Propylene Glycol must be added for pump lubricity and to prevent freezing of pipes. Refrigerant to water heat exchanger is required for system to function. Lost energy in exchange process. Majority of phase change occurs in secondary heat exchanger, resulting in low energy transfer.
Uses more refrigerant. Requires an average of 6 lbs per system ton. R-22 refrigerant is safe by EPA standards. Mineral oil is used to lubricate compressor. No need for make-up water due to leakage or evaporation.	Uses less refrigerant. Requires large amounts of water and 30% glycol solution to charge system. When combined with labour to install and purge loop field, actual cost can be higher. Make-up water required.
Less Invasive If a leak occurs, the location is determined by pressurizing system with mixture of Freon and Nitrogen and simple refrigerant leak detectors. Indoor location - Nitrogen purge while brazing leak area. Pressure check, evacuate and recharge system. Outdoor location - A shovel is used to uncover manifold pit, (Installing Contractor, Sales Rep and Manufacturer have records of manifold location) leak located. If leak is in manifold joint, simply re-braze. If it is determined that the leak is within the actual loop, many times the loop can be isolated, system recharged and put back in operation without drilling or excavation. In either scenario if loop replacement is required, the impacted land needing to be disturbed is 50-75% less.	More Invasive Leakage occurs inherently due to the pump and clamps sealing mechanisms. That is why a make up reservoir is installed with this type of system. If the leak is not excessive, most often you will be told to just add make-up water. (Ongoing maintenance that you spent money to avoid.) If an unacceptable leak occurs: Indoor location - A visual inspection will determine location. Many times the clamps used to secure the pipe begin to leak; a simple tightening may be all that is needed. Outdoor location - Large areas of the yard will may have to be dug up with a backhoe or similar machine to locate source of leak. (Assuming accessibility is not an issue.) Isolation of a loop is not an option. In either location, if leak is in a fused joint then potentially the entire water/glycol charge will have to be removed, pipe refused, system refilled and purged.

 

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The Geothermal Earth Loop

Energycore Earth Loops enable direct exchange of renewable thermal energy with the earth. Standard refrigeration tubing is used because of its high thermal conductivity.

An important savings in installation cost of the EarthLinked^® system is the reduction in drilling cost for the small bore holes. The 3" holes for the system require drilling only 11% of the volume of the 6" holes required for other GeoExchange systems.

Earth Loop Installation Options

The loops are designed in three different configurations (horizontal, vertical and diagonal) to meet most new and retrofit applications. This allows for the selection of the most economical loop configuration for each installation.

Horizontal:
The horizontal loop application is an excellent choice for areas where overburden depths of at least 4-6' exist. Excavation costs must be compared to the cost of drilling either the vertical option or the diagonal option illustrated above.

There are also restrictions that apply to the horizontal loop field such as the inability to plant deep-rooting trees, erect buildings such as garages or out-buildings, and swimming pools (either in-ground or above-ground) would be prohibited. Despite these restrictions however, a number of homeowners opt for this type of loop field and successfully implement this design on a regular basis.

Vertical:
The vertical loop application is available in all areas of the country. For this type of loop application, the services of a drilling contractor would be required to drill the 3" bore hole required for the loop itself.
As you can see from the illustration, the vertical loop option requires less space and therefore minimizes restrictions in use above the loop field.

Diagonal:
The diagonal loop is probably the best choice in loop application. With its small "footprint" there are minimal restrictions in use above the loop field; this allows the property owner complete freedom to utilize their property in any way they choose. The manifold area is the only area that must be protected from buildings, trees or pools above.
As with the vertical loop option, the diagonal also requires the services of a drilling contractor to drill the 3" bore holes required.

Fast, Easy Installations

Loops using vertical or diagonal bore holes are typically installed in less than two days. Horizontal loops can be installed in a single day.

Energycore Geothermal loops are easier to install because they use a much smaller bore hole and less excavation than water-based systems. Therefore, smaller and more manoeuverable drilling equipment can be used.

 

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The Heat Pump

Energycore's geothermal heat pump is a highly effective pump. It is supplied by ECR and this article describes how it functions.

Effective Geothermal Harnessing

EarthLinked^® systems are the most effective method of harvesting the earth's renewable energy for the purpose of providing domestic hot water and heating/cooling for buildings.

Highly versatile, ECR's refrigerant flow controls have successfully operated commercial refrigeration systems, air source heat pumps from one to 15-ton capacity, a variety of GeoExchange systems produced by various manufacturers, closed-loop geothermal units , multi-compressor units, and radiant hydronic heating systems.

These unique flow controls also make possible the inclusion of desuperheating or integrated water heating on any heat pump system without the need for electronic controls.

An Efficient Refrigerant Management System

The use of small refrigerant tubes for heat exchange in the earth is made possible by the Refrigerant Management System which consists of the Liquid Flow Control (LFC) and the Active Charge Control (ACC). Together, they achieve high efficiency direct expansion and condensation of refrigerant in the earth through Direct GeoExchange.

ECR Refrigerant Flow Controls: Reliable and Stable

Until the development of ECR's Refrigerant Flow Controls, no simple controls or metering devices existed that could deliver refrigerant in the condition appropriate to each component throughout the entire operating cycle and continually maintain stable refrigerant conditions.

Special refrigerant flow controls were necessary to manage the refrigerant in the long evaporator-condenser which is buried in direct contact with the heat source. ECR's refrigerant management system serves this need and provides:

• Stable refrigerant management under all loading conditions.
• Continuous return of lubricating oil to the compressor without any liquid refrigerant.
• Improved system efficiency, reliability and serviceability.

The Components of Heat Pumps

To operate at optimum efficiency, the three major components of all heat pumps require the refrigerant to be in a particular physical state appropriate to each component (the compressor, condenser and evaporator).

The compressor needs a dry refrigerant vapour from the evaporator, containing little or no superheat at the compressor inlet.

The condenser needs its refrigerant outlet pressure to be just sufficient to cause the refrigerant vapour to complete its condensing just before it reaches the condenser outlet.
This provides high pressure vapour to the entire condenser for maximum condensing with no uncondensed vapour passing through the condenser and no liquid refrigerant "backed up" in the condenser, thus eliminating subcooling.

In contrast, the evaporator needs liquid refrigerant at its inlet.
The liquid should then complete its evaporation just as it reaches the evaporator outlet. This is the optimum "flooded" evaporator condition which produces maximum system efficiency when no portion of the evaporator is wasted in producing superheat. Any unevaporated refrigerant which passes through or out of the evaporator should not reach the compressor.

Why Conventional Controls cannot surpass ECR's Refrigerant Flow Controls

Conventional controls include thermostatic expansion valves (TXVs), electronic expansion valves (EXVs), automatic expansion valves (AXVs), fixed orifices, capillary tubes, and accumulators.

No combination of these can assure simple, stable operation of a Direct GeoExchange system or achieve all the following conditions which ECR's controls maintain in any standard air conditioning system, including:

• A fully condensing condenser - minimal subcooling.
• A continuously flooded evaporator - no superheat.
• Dry vapour with no superheat at the compressor inlet.
• A simple, easy method of determining when the system is properly charged.

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Cooling Mode of the Geothermal Heat Pump

In the cooling mode, cool vapour (green in the graphic) arrives at the compressor after absorbing heat from the air in the building. The compressor compresses the cool vapour into a smaller volume, increasing its heat density.

The refrigerant exits the compressor as a hot vapour (red in the graphic) which then goes into the earth loop field.
The loops act as a condenser condensing the vapour until it is virtually all liquid. The refrigerant leaves the earth loops as a warm liquid (yellow in the graphic).

The flow control regulates the flow from the condenser such that only liquid refrigerant passes through the control. The refrigerant expands as it exits the flow control unit and becomes a cold liquid (blue in the graphic).
Because the liquid evaporates as it passes through the cooling coil located in the air handler, it absorbs heat from the air blowing over the coil surface and thus cools your home.

Continue reading to find out how the Geothermal Heat Pump works in Heating mode

 

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Heating Mode of the Geothermal Heat Pump

In the heating mode, the refrigerant enters the earth loops as a cold liquid (blue in the graphic) and comes out as a cool vapour (green in the graphic).

When a refrigerant evaporates it absorbs a large quantity of heat from any surrounding material. Therefore as the refrigerant flows through the loops, it absorbs heat from the earth and stores it in vapour form for later release.

The cool (green) vapour that is heat-charged after leaving the earth loops then enters the compressor where its temperature is raised from about 4^o C to about 71^o C.

During this compression stage, the temperature of the vapour increases because of the intense compression and the vapour leaves the compressor (red in the graphic) hotter than the air in the building being heated.

Because the vapour leaving the compressor and entering the condenser is hotter than the inside air, heat flows into the air flow from the vapour as the air passes the blower. This warms your home.

As the heat is removed while the hot vapour passes through the condenser, the vapour condenses more and more until it exits the condenser as a liquid. This warm liquid (yellow in the graphic) enters the flow control unit, which monitors the amount of vapour arriving at the liquid flow control (LFC), and meters liquid only through the device for its return to the earth loop field.

Find out how the cooling system works as well!

 

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Design Features

Design features of the internal cabinet box for the Earthlinked^® Commercial Water Heating Geothermal system:

• Highest efficiency
• Simplicity of design
• Adaptive Refrigerant Management Controls give a clear advantage
• Compact ( 22" x 17" x 28")
• 16 Gauge Insulated Cabinet, with wrap-around sheet metal designed for easy service access
• Discharge Line Assembly includes High Pressure Cutout Switch; the pre bent tubing minimises factory braze joints
• Includes Discharge Line Sub Assembly
• Suction Line Assembly includes Low Pressure Cutout Switch; the pre bent tubing again minimises factory braze joints
• Features an Active Charge Control, with 8" diameter and is powder coated and insulated
• Has a Base Pin that holds Active Charge Control (ACC) in place during shipping
• Front is mounted for easy sigh glass viewing
• Nickel plated sight glasses eliminate the potential for rust

Visit Energycore's website for diagrams of the system.

 

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