What is GeoExchange? - Page 6
| Article Index |
|---|
| What is GeoExchange? |
| Page 2 |
| Page 3 |
| Page 4 |
| Page 5 |
| Page 6 |
| Page 7 |
| All Pages |
Page 6 of 7
Open Loop System. This type of loop configuration is used less frequently, but may be employed cost-effectively if ground water 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. 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.
Standing Column Well System. Standing column wells, also called turbulent wells or Energy WellsTM, have become an established technology in some regions, especially the northeastern United States. Standing wells are typically six inches in diameter and may be as deep as 1500 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 Temperate water from the bottom of the well is withdrawn, circulated through the heat pump’s heat exchanger, and returned to the top of the water column in the same well. Usually, the well also serves to provide potable water. However, ground water must be plentiful for a standing well 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, which makes the system act like a true 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 locality to locality, but are eased by the fact that the quantities are small and the water is never treated with chemicals.
Other loop designs are also being used. In a few places, for example, home builders have installed large community loops, which are shared by all of the homes in a housing development.
Purchasing a System
To ensure they receive the highest-quality equipment, system design and installation, consumers should consider the following guidelines when shopping for a GeoExchange system:
Ratings and Certification: Look for equipment that is certified by the Air-Conditioning and Refrigeration Institute (ARI), a non-profit organization that rates the performance of residential and small commercial geoexchange equipment. Certified equipment carries the ARI seal.
Warrantees: Manufacturers’ terms of warranty vary. To assure a high-quality installation, seek a performance guarantee on the installed system, as opposed to coverage limited to the heat pump itself.
Sizing: GeoExchange systems that are too large waste energy and do not provide proper humidity control. Check to see that the contractor carefully determines your home’s heating and cooling requirements using accepted procedures, such as those recommended by the Air Conditioning Contractors Association. The actual size of the system should be within 15 percent of the calculated load.
