Welcome to EcoTrol Loop Configurations

By: Architectural/residential Technologies  09-12-2011
Keywords: heating and cooling


This configuration is usually the most cost effective when adequate yard space is available and trenches are easy to dig. Workers use trenchers or backhoes to dig the trenches three to six feet below the ground and then lay a series of parallel plastic pipes. They backfill the trench, taking care not to allow sharp rocks or debris to damage the pipes. Fluid runs through the pipe in a closed system. A typical horizontal loop will be 400 to 600 feet long per ton of heating and cooling capacity.

The pipe may be curled into a slinky shape in order to fit more of it into shorter trenches, but while this reduces the amount of land space needed it may require more pipe. Horizontal ground loops are easiest to install while a home is under construction. However, new types of digging equipment that allow horizontal boring are making it possible to retrofit geoexchange systems into existing homes with minimal disturbance to lawns. Horizontal boring machines can even allow loops to be installed under existing buildings or driveways.


These loops are ideal for homes where yard space is insufficient for horizontal trenching, when the Earth is rocky close to the surface, or for retrofit applications where minimum disruption of the landscaping is desired. Contractors bore vertical holes 150 to 450 feet deep in the ground. Each hole contains a single loop of pipe with a U-bend at the bottom. After the pipe is inserted, the hole is backfilled or grouted. Each vertical pipe is then connected to a horizontal pipe, which is also concealed underground. The horizontal pipe then carries fluid in a closed system to and from the geothermal system. Vertical loops are usually more expensive to install, but require less piping than horizontal loops because, deeper down, the Earth is cooler in summer and warmer in winter.


If a home is near a body of surface water, such as a pond or lake, this loop design may be the most economical. The fluid circulates through polyethylene piping in a closed system. Workers run the pipe to the water, where long sections are then submerged.

The pipe may be coiled in a slinky shape to minimize space requirements. Geoexchange experts recommend using a pond loop only if the water level never drops below six to eight feet at its lowest level to assure sufficient heat-transfer capability. Pond loops used in a closed system result in no adverse impact on the aquatic system.


Less frequently used, these systems are cost-effective if ground water is plentiful. They are the simplest to install and have been used successfully for decades in areas where local codes permit. In this type of system, ground water from an aquifer is piped directly from the well to the building, where it transfers its heat to a heat pump. After it leaves the building, the water is pumped back into the same aquifer via a second well - called a discharge well -

located at a suitable distance from the first. Local environmental officials should be consulted whenever an open loop system is being considered.

Also called turbulent wells, these systems have become an established technology in some regions, especially the north eastern United States. Standing wells are typically six inches in diameter and may be as deep as 1,500 feet. Temperate water from the bottom of the well is withdrawn, circulated through the heat pump’s heat exchanger, and returned to the top of the water column in the same well. The same well can also provide potable water.

Ground water must be plentiful for this system to operate effectively. If the standing well is installed where the water table is too deep, pumping would be prohibitively costly. Under normal circumstances, the water diverted for building (potable) use is replaced by constant-temperature ground water, and the system performs like an open-loop system. If the well-water temperature climbs too high or drops too low, water can be "bled" from the system to allow ground water to restore the well-water temperature to the normal operating range. Permitting conditions for discharging the bleed water vary from region to region, but are eased by the fact that the quantities are small and the water is never treated with chemicals.

Keywords: heating and cooling

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