Geothermal Loops
Geothermal Heating Cooling
Loops
The Earth Piping:
Once installed, the ground loop in a GHP system remains out of sight beneath the Earth’s surface while it works unobtrusively to tap the heating and cooling nature provides. The loop is made of a material that is extraordinarily durable but which allows heat to pass through efficiently. This is important so it doesn’t retard the exchange of heat between the Earth and the fluid in the loop. Loop manufacturers typically use high-density polyethylene, a tough plastic. When installers connect sections of pipe, they heat fuse the joints. This makes the connections stronger than the pipe itself. Some loop manufacturers offer up to 50-year warranties. The fluid in the loop is water or an environmentally safe antifreeze solution that circulates through the pipes in a closed system.Another type of geothermal heating cooling is direct exchange (DX), which utilizes copper piping buried underground. As refrigerant is pumped through the loop, heat is transferred directly through the copper to the earth. To ensure good results, the piping should be installed by professionals who follow procedures established by the International Ground Source Heat Pump Association (IGSHPA). Installers should be certified by IGSHPA or be able to show equivalent training by manufacturers or other recognized authorities at a recognized institution.The length of the ground loop depends upon a number of factors, including the type of loop configuration used; a home’s heating and air conditioning load; soil conditions; local climate; and landscaping. Larger homes with larger space conditioning requirements generally need larger loops than smaller homes. Homes in climates where temperatures are extreme also generally require larger loops.
A heat loss/heat gain analysis should be conducted before the loop is installed.
Types of Loops:
Most loops for residential systems are installed either horizontally or vertically in the ground, or submersed in water in a pond or lake. In most cases, the fluid runs through the loop in a closed system, but open-loop systems may be used where local codes permit. Each type of loop configuration has its own, unique advantages and disadvantages, as explained below:
Horizontal Ground Closed Loops:
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, 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.
Vertical Ground Closed Loops:
This type of loop configuration is ideal for homes where yard space is insufficient to permit horizontal buildings with large heating and cooling loads, 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 in the ground 150 to 450 feet deep. 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 heat pump. Vertical loops are generally more expensive to install, but require less piping than horizontal loops because the Earth deeper down is cooler in summer and warmer in winter.
Pond Closed Loops.
If a home is near a body of surface water, such as a pond or lake, this type of loop design may be the most economical. The fluid circulates through polyethylene piping in a closed system, just as it does in the ground loops. Typically, workers run the pipe to the water, then submerge coils of piping under the water. Pond loops are typically used only if the water level never drops below six to eight feet at its lowest level to assure sufficient heat-transfer capability. Properly designed pond loops result in no adverse impacts on the aquatic system.
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 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.
Geothermal Heat Pump Specialists
1.800.282.1505
Maitz Home Services Serves the Counties of: Lehigh, Northampton, Berks, Monroe,
Upper Bucks, and Upper Montgomery and the following cities.
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Allentown PA 18102 - 18103
Bath PA 18014
Bethlehem PA 18015
Coopersburg PA 18036
Easton PA 18045
Emmaus PA 18049
Fleetwood PA 19522
Hellertown PA 18055
Kutztown PA 19530
Lehigh Valley PA
Macungie PA 18062
Mount Pocono PA 18344
Nazareth PA 18064
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Northampton PA 18067
Pennsburg PA 18073
Tobyhanna PA 18466
Quakertown PA 18951
Reading PA 19606
Salisbury PA 18103
Stroudsburg PA 18360
South Whitehall PA 18104
Topton PA 19562
Whitehall PA 18062
Bethlehem Twp PA18017
Coopersburg PA 18035
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