Typical Information about Ground Source Heat Pump Systems

Millions of homeowners globally are enjoying a high level of comfort and significantly reducing their energy use today with GeoExchange (geothermal) heating and cooling systems.

This marvelous technology relies primarily on the Earth’s natural thermal energy, a renewable resource, to heat or cool a house or commercial buildings. The only additional energy GeoExchange systems require is the small amount of electricity they employ to concentrate what Mother Nature provides and then to circulate high-quality heating and cooling throughout the home.

Homeowners who use GeoExchange systems give them superior ratings because of their ability to deliver comfortably warm air, even on the coldest winter days, and because of their extraordinarily low operating costs. As an additional benefit, GeoExchange systems can provide inexpensive hot water, either to supplement or replace entirely the output of a conventional, domestic water heater.

GeoExchange heating and cooling is cost effective because it uses energy so efficiently. Environment is a high priority which is why the Government is introducing a Renewable Heat Incentive tarrif. This is taken in to account if you need to replace or upgrade an existing system along with the long term financial benefits are a bonus to saving the planet.

Owners of GeoExchange systems can relax and enjoy high-quality heating and cooling year after year. GeoExchange systems work on a different principle than an ordinary heating systems, and they require little maintenance or attention from homeowners. Furnaces must create heat by burning a fuel-typically natural gas, propane, or fuel oil. With GeoExchange systems, there’s no need to create heat, hence no need for chemical combustion. Instead, the Earth’s natural heat is collected in winter through a series of pipes, called a loop, installed below the surface of the ground or submersed in a pond or lake. Fluid circulating in the loop carries this heat to the home. An indoor GeoExchange system then uses electrically-driven compressors and heat exchangers in a vapor compression cycle-the same principle employed in a refrigerator-to concentrate the Earth’s energy and release it inside the home at a higher temperature.

In summer, the process is reversed in order to cool the home. Excess heat is drawn from the home, expelled to the loop, and absorbed by the Earth. GeoExchange systems provide cooling - the same way that a refrigerator keeps its contents cool-by drawing heat from the interior, not by injecting cold air.

GeoExchange systems do the work that ordinarily requires two appliances, a heating system and an air conditioner. They can be located indoors because there’s no need to exchange heat with the outdoor air. They’re so quiet homeowners don’t even realize they’re on. They are also compact. Typically, they are installed in a basement or attic, and some are small enough to fit in a closet. The indoor location also means the equipment is protected from mechanical breakdowns that could result from exposure to harsh weather.

GeoExchange works differently than conventional heat pumps that use the outdoor air as their heat source or heat sink. GeoExchange systems don’t have to work as hard (which means they use less energy) because they draw heat from a source whose temperature is moderate. The temperature of the ground a few metres beneath the Earth’s surface remains relatively constant throughout the year, even though the outdoor air temperature may fluctuate greatly with the change of seasons. At a depth of approximately 2m for example, the temperature of soil in most of the world’s regions remains stable between 45 F and 70 F. (converter)
This is why well water drawn from below ground tastes so cool even on the hottest summer days.

In winter, it’s much easier to capture heat from the soil at a moderate 50F. Than from the atmosphere when the air temperature is below zero.
Conversely, in summer, the relatively cool ground absorbs a home’s waste heat more readily than the warm outdoor air. Studies show that approximately 70 percent of the energy used in a GeoExchange heating and cooling system is renewable energy from the ground. The remainder is clean, electrical energy which is employed to concentrate heat and transport it from one location to another. In winter, the ground soaks up solar energy and provides a barrier to cold air. In summer, the ground heats up more slowly than the outside air.

Making Hot Water

GeoExchange systems can also provide all or part of a household’s hot water. This can be highly economical, especially if the home already has a GeoExchange system, hence a ground loop, in place.
One economical way to obtain a portion of domestic hot water is through the addition of a desuperheater to the GeoExchange unit. A desuperheater is a small, auxiliary heat exchanger that uses superheated gases from the heat pump’s compressor to heat water. This hot water then circulates through a pipe to the home’s water heater tank. In summer, when the GeoExchange system is in the cooling mode, the desuperheater merely uses excess heat that would otherwise be expelled to the loop. When the GeoExchange unit is running frequently, homeowners can obtain all of their hot water in this manner virtually for free. A conventional water heater meets household hot water needs in winter if the desuperheater isn’t producing enough, and in spring and fall when the GeoExchange system may not be operating at all.
Because GeoExchange systems heat water so efficiently, many manufacturers today are also offering triple function GeoExchange systems. Triple function systems provide heating, cooling and hot water. They use a separate heat exchanger to meet all of a household’s hot water needs.

The Earth Connection

Once installed, the loop in a GeoExchange 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.

Types of Loops

Most loops for residential GeoExchange 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 – Till now this configuration is usually the most cost effective when adequate garden space is available and trenches are easy to dig. Workers use trenchers or mechanical excavators 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. 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. www.molingservices.com

Vertical Ground Closed Loops. This type of loop configuration is ideal for homes where garden space is insufficient to permit horizontal buildings with large heating and cooling loads, or for retrofit applications where minimum disruption of the landscaping is desired. Contractors bore vertical holes 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 GeoExchange system. Vertical loops were 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 long sections under water. The pipe may be coiled in a slinky shape to fit more of it into a given amount of space. 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 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.

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 British and European Standards. Certified equipment carries the BS EN seal of approval.

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 Ground Source Heat Pump Association. The actual size of the system should be within 15 percent of the calculated load.

System Design: While designing a residential GeoExchange system is not particularly complicated, always use experienced contractors. The contractor should carefully select the size of the GeoExchange system, the size and design of the loop, and the type of fluid that will circulate through it. The contractor should also examine ways to use the GeoExchange system to provide hot water. Finally, the contractor should examine your home to ensure the ductwork is designed and installed properly to prevent leaks, as well as to ensure it is properly insulated and has window glazing and other energy-efficiency features. Minimizing heating and cooling needs reduces the required size, hence the cost, of the GeoExchange system.

Sound Investment
GeoExchange is becoming the system of choice in many parts of the United States as consumers learn more about its aesthetic advantages and long-term value, and as it becomes more widely available.
GeoExchange is no longer just for the affluent, a reputation it once held because typical early buyers were owners of upper class homes. They wanted the quiet comfort GeoExchange systems provide, and they were more than willing-and could afford-to pay the cost premium associated with early systems. This is because the extraordinarily low operating costs of GeoExchange systems more than make up for any higher installation costs within a few years. It is calculated an installation should save in the region of 70% of heating costs, compared to conventional systems. GeoExchange systems also save money in other ways. They are highly reliable, require little maintenance, and are built to last for decades. They add considerably to the value of homes.

Today, homeowners in all income brackets can take advantage of the benefits of GeoExchange heating and cooling. Initial costs have declined substantially as many more builders and heating and cooling contractors nationwide make GeoExchange systems available, and as innovative techniques enable the loops to be installed more quickly (often in one day) and for lower cost see www.geomole.co.uk.

What’s more, some electric utilities around the world as well as Governments have incentive programmes and low-interest financing programmes which can make GeoExchange more affordable. Home owners can begin saving from day one, and then go on saving money and the Environment year after year.

Today, the major barrier to wider use of this marvelous technology is the fact that many consumers simply are not aware it is there and until Geo-mole did not physically have room for an installation.

A Wise Choice

GeoExchange is a smart investment for consumers who want a system that provides a high level of comfort and low monthly energy bills for as long as they own their homes.

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