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Geothermal/Geoexchange Systems Tutorial
 Introduction
Homeowners in most regions of North America are enjoying unsurpassed
levels of comfort and significantly reduced energy costs by using leading
edge geothermal central heating and cooling. This technology relies
primarily on the earth's natural thermal energy, "a renewable resource",
to heat or cool a house or multifamily dwelling. The only additional
energy geothermal systems require is a minimal amount of electricity they
employ to concentrate the natural thermal energy which, Mother Nature
provides and to circulate high quality, central heating and cooling
throughout the home.
Homeowners who use Geothermal systems rate them as superior to other
conventional heating and cooling systems because of their ability to
deliver comfortably warm air and/or hydronic in-floor heating, even on the
coldest winter days and because of their extraordinarily low operating
costs. Since a Geothermal System is reversible, they offer the added
benefit of central A/C and dehumidification. As an additional benefit,
geothermal systems can provide inexpensive domestic hot water, either to
supplement or replace entirely the output of a conventional, domestic
water heater.
Geothermal heating and cooling is cost effective because it uses renewable
underground energy, in an extremely efficient manner. In the heating
season, a Geothermal System will absorb approximately 70% of the energy
from the ground and the remaining 30% would come from the electrical grid.
For this reason, GSHP Systems are considered, very environmentally
friendly and many government agencies endorse geothermal technologies.
Geothermal Systems are the most energy efficient heating and cooling
systems available.
How Geothermal Systems Work
Each year, the sun supplies us with about 500 times more energy than we
could possibly use. The Earth absorbs solar energy and retains it below
the frost level, thereby creating a constant temperature of 50ºF to 70ºF,
depending on geographic location. Working with a customized underground
loop or open well water system, the geoflex complete system (patent
pending) utilizes this constant temperature to exchange energy between
your home and the Earth, as needed for heating and cooling. Geothermal
Systems dramatically reduce CO2 emissions, as compared to fossil fuel
burning systems, which add to the CO2 emission problem. The specific
amount of CO2 reduction would be based on the electrical fuel grid in a
given country or region. Since a Geothermal System does not burn fossil
fuels, a chimney is not needed in the home.
In the heating season,
the open or closed loop fluid/well water is circulated the through the
system to absorb heat from the earth/water, and then that heat is
transferred to your home. The geothermal system processes the extracted
heat and compresses it to a higher temperature, which is then distributed
throughout the home using traditional duct systems.
In the air conditioning season,
the heating process is reversed, and the geothermal unit absorbs heat from
inside the home and sends it back to the cooler earth. The energy then
re-warms the Earth for the next heating season.
By using the natural temperature of the earth, a geothermal system is the
most efficient method available to provide year round comfort and high
efficiency performance. There are many basic energy sources available to
earth energy systems or ground-source heat pump (GSHP) customers. The
most common energy sources are, "Closed Vertical
Loop", "Closed Horizontal Loop", "Closed Pond, River or Lake Loop" or and
"Open Well" System. You are standing on a free energy source. The secret
is, how we economically take advantage of these energy sources available
to us.
Technology
An earth energy installation or ground-source heat pump (GSHP) is one of
the most efficient means available to provide space heating/cooling for
homes and offices, in virtually all regions throughout the world. It
transfers the heat located immediately under the earth's surface (or in a
body of water) into a building in winter, using the same principle as a
refrigerator that extracts heat from food and rejects into a kitchen. A
heat pump takes heat from its source at a low temperature and discharges
it at a higher temperature, allowing the unit to supply more heat than the
equivalent energy supplied to the heat pump.
Many people are familiar with air-to-air heat pumps, which use outdoor air
as the source of heat. These units are well suited for moderate climates,
but they do not operate efficiently when the outdoor temperature drops
below -10?C and there is little "heat" left in the air to extract. It is
more difficult to extract or reject heat to air because of its low
density. A Liquid Energy Source will always outperform an "air to air"
system, even given the same operating temperatures.
Environmental Benefits
Governments and energy planners prefer GSHP technology because it is an
environmentally benign technology, with no emissions or harmful exhaust.
The GSHP industry was the first to move away from damaging CFCs
(chlorofluorocarbons). Since geothermal systems take 70% of the energy
they use from the earth, the environmental benefits are obvious. Although
GSHP units require electricity to operate the components, a high COP means
that GSHP systems provide a significant reduction in the level of CO2, SO2
and N0x emissions (all linked with the issue of greenhouse gas emissions
and global warming).
Durability
Geothermal Systems last longer than conventional systems since they are
self-contained, sitting in the place where a standard furnace would sit,
completely indoors. Therefore, a Geothermal System is sheltered from
extreme outside weather conditions. The system has no noisy, rattling
parts to disturb your family. Also, since they are completely inside your
home, you will eliminate any noise complaints from your neighbours. A
Geothermal System has few moving parts subject to breakdown, helping to
keep maintenance to a minimum. With a properly maintained system, the
homeowner will enjoy many years of unencumbered comfort. Simple
maintenance would include, changing the filter and yearly oiling of the
fan motor, as with most conventional furnace and A/C Systems. If an open
well system is used the maintenance would include, inspection and
maintenance of the well water supply.
General Cost
Earth energy heat pumps provide one of the lowest life-cycle costs for
heating and cooling in North America (i.e. the total cost for initial
installation and annual operating costs, will be lower than the comparable
cost for a conventional heating/cooling system). Earth energy technology
is different from a gas or an oil furnace, and it is a long-term
investment in comfort and home equity. If a homeowner requests regular
servicing, this could easily be arranged through a service contract.
Proper performance reflects the quality of installation. Consumers should
insist a reputable geothermal contractor install the system. The national
installation standard in Canada (CSA C445) addresses aspects of design and
installation, but many important points are left to the discretion of the
contractor and/or manufacturer. With a bit of homework by the homeowner,
the design and installation of an earth energy unit will provide many
years of trouble-free operation and lower costs.
Comfort Advantages
A GSHP system warms air in smaller increases over a longer period of time,
as compared to the "burst" of a combustion oil or gas furnace. As a
result, homeowners notice a stable level of heat with no peaks or troughs,
less drafts, etc.
Terminology
Due to the large demand for GSHP as cooling devices in the United States,
the earth energy industry uses the term "ton" to describe a unit that will
provide approximately 12,000 BTU's of cooling or heating capacity. The
cooling capacity on average, for a typical 2,000 square-foot new residence
would require a 4-ton unit for sufficient heat, depending on the location.
Co-efficient of Performance (COP)
The major advantage of a GSHP system is that the heat obtained from the
ground (via the condenser) is much greater than the electrical energy that
is required to drive the various components of the system. The efficiency
of a unit is the ratio of heat energy provided versus the electrical
energy consumed to obtain that heat, and it is called its "Coefficient of
Performance" (COP). As an example, under the "Energy Efficiency Act" in
Canada all GSHP units that are sold must exceed a COP of 3.0 (i.e. for
every kilowatt of electricity needed to operate the system, the GSHP
provides three kilowatts of heat energy).
With a COP of 3.0, the cost of
heating would be one-third (i.e. two-thirds less) of the cost to operate
an electric resistance heating system, such as baseboards or electric
furnace. With a COP of 4.0, the savings can be as much as three-quarters
off the price of electric heating, with an EER at 14 the cooling costs
will also be reduced dramatically. As earth energy technologies and
techniques improve and as the COP increases, the operating savings also
increase.
Electrical Efficiency Ratio (EER)
EER is the "Steady State", "energy efficiency ratio" rating when operating
in the cooling mode. EER ratings are arrived at by, dividing the cooling
output of the Geothermal Heat Pump (in Btu/Hour) by, the power input (in
Watts). For example an EER of 14 would mean that you would receive 60,000
BTU's for the cost of 4286 watts or 4.286 kW. If your electrical rate is
$.06/kW, you would pay (6X4.286) to run a 5 ton, 60,000 BTU forced air
cooling system. Fuel prices and electrical prices vary dramatically
throughout North America and Europe. You may have come across a SEER
rating. This is an acronym for Seasonal Energy Efficiency Ratio, which is
commonly used to calculate the general efficiency of a conventional "air
to air" heat pump or standard air conditioner. A Geothermal heat pumps
efficiency does not fluctuate because of outdoor air temperatures, as with
"air to air" systems, therefore the "steady state" EER rating is commonly
used by the industry. Do not be confused the two ratings are not
comparable.
Heat Loss
A very important first step in the design of a GSHP installation is to
determine how much heat or cooling is required to satisfy your comfort
level. There are standards to calculate the heat loss and heat gain
throughout the world The national Canadian installation standard for
residential earth energy units (CSA C445) states that the heat loss must
be calculated in accordance with a recognised heat loss program. This
method needs to establish, the insulation levels of all walls, ceilings
and windows, the number of occupants, your geographic location and soil
type, and many other factors, to determine the total annual heat loss in
British Thermal Units (BTU) or kilowatts (kW). It will also calculate the
heat gain, which is used to determine the cooling load for summer (all
units will generally provide sufficient cooling, if the unit is large
enough to provide sufficient heat). With this final heat loss, the
installed unit will match your specific demand.
Balance Point
The outdoor temperature at which a GSHP system can fully satisfy the
indoor heating requirement is referred to as the balance point, and is
usually -10oC in most regions of Canada and the Northern U.S.,
specifically. At outdoor air temperatures above this balance point, the
GSHP cycles on and off to satisfy the demand for heat indoors. At
temperatures below this point, the GSHP unit runs almost continuously, and
will also turn on the auxiliary heater (called second stage heat) to meet
the demand. In the case where a large residence is concerned, it is common
for the GSHP heat pump to be sized to cover 100% of the heat loss.
Normally a larger home would require a "Two Stage" or "Dual Staged" (two
compressor sections in one unitary system) unit to accomplish this goal. A
two-stage system will run at two separate speeds while maintaining the
same COP on either speed. This differs on a two speed system in that, a
"Two Speed System" will drop the COP when operating in high speed mode,
whereas a Two Stage System will not. In a Two Stage System the second
compressor becomes the second stage heat/cool. The secondary benefit to a
Two Staged System is that the customer can use both stages to cool when
the outdoor temperatures increases dramatically in a short period of time,
as is common in many locations, globally.
Auxiliary/Emergency Heat
When the outdoor air temperature drops below the design balance point, the
GSHP unit cannot meet the full heating demand inside the house (for units
sized to 100% of heat loss, this is not an issue). The difference in heat
demand is provided by the supplementary or auxiliary heat source, usually
an electric resistance element or in some cases a hydronic hot water coil,
positioned in the unit's plenum. Like a baseboard heater, the COP of an
"electric" auxiliary heater is 1.0, so excessive use of backup heat
decreases the overall efficiency of the GSHP system and increases
operating costs for the homeowner. A Hydronic fan coil can be employed
where a customer has the opportunity to use hot water directly from their
domestic hot water tank to help boost the heat output at times of high
demand. A hydronic hot water coil would only be used when the customer has
a low operating cost (fuel type is the key), quick response, hot water
tank available. Using a GSHP complete with a Hydronic Hot Water Coil as
backup is commonly referred to as a Dual Fuel System. An electric Hot
water tank would not be used in this application, except where a Demand
Hot Water Option has been built into the GSHP. See Hot water Options
Sizing
GSHP units do not generally need to meet 100% of the calculated heat loss
of a building, as long as they have an auxiliary electric or hydronic
coil, heating source for backup and for emergencies. Almost 90% of a
home's heat load can be met by a GSHP unit that is sized to 70% of the
heat loss, with the remaining 10% of load supplied by the auxiliary plenum
heater. You should note that, a homes heat loss is directly related to
outdoor temperatures. Therefore even if the system is sized at 70% of the
heat loss, the temperature may only drop for a short duration. Over sizing
can result in control and operational problems in the cooling mode,
especially if the GSHP unit has a single-staged compressor, and the
installed cost will increase significantly for little operational savings.
Conversely, under-sizing will lower the installed cost, but the additional
length of time that the GSHP unit will operate will place excessive demand
on many components and may result in unacceptable chill. Although the
Canadian CSA standard for installations says that 60% is the minimum, the
industry has moved to a sizing level of 70% to 80% of heat loss, as an
optimal design size.
Hot Water Options
Desuperheaters and Partial Hot Water (PHW) are the most popular hot water
option, usually adding less than $1,000 to the total installation, but
reducing approximately 60% to 70% of domestic hot water heating cost to an
average household. This option is automatically activated to heat hot
water whenever the system is operating either in the heating, cooling or
"Demand Hot Water" mode. A desuperheater can be set up as "low" or "high"
priority, depending on whether the homeowner wants the ground heat
diverted to the domestic hot water first (thereby turning on the auxiliary
backup heater) or to heat water only after the space heating requirement
has been satisfied. In the cooling mode the Desuperheater will take hot
water off the system for domestic hot water use, instead of rejecting the
heat to the ground loop which essentially causes free hot water.
On Demand Hot Water systems (ODHW) are most commonly used to heat a
hydronic in-floor or a zoned hydronic hot water air coil heating system.
With a specifically designed water coil, an On Demand Hot Water System can
also be used to heat an indoor or outdoor swimming pool on demand. The
difference between a Desuperheater (PHW) and a On Demand Hot Water (ODHW)
system is that the Desuperheater will heat a small portion of the domestic
hot water, only when the other modes are operating. An On Demand Hot Water
System will turn on simply to make hot water with no other modes operating
and the amount of hot water will be based on the size of the main systems
compressor. An On Demand Hot Water System tied directly to a hot water
tank, would be considered a "Quick Response" system.
Air Distribution
GSHP units work efficiently and offer excellent comfort levels because
they provide a small temperature rise, but this means that the air coming
through the register on your floor is not as hot as the air from a gas or
oil furnace. A GSHP unit must heat more air to supply the same amount of
heat to your house, and duct sizes are generally slightly larger than
those used for combustion furnaces to accommodate the higher CFM (cubic
feet per minute) air flow. The ducting is designed to reduce air noise at
every point within the ducting system. It is standard practice to insulate
the ducts with noise dampening duct insulation at least 10 feet from the
system. It is also common practice to use canvas connections at the main
supply and return plenum to avoid noise migration to the house. These two
issues are generally covered under installation practices and procedures.
Although all installers will strive to keep competitive, issues such as
these should never be overlooked for cost savings.
Optional Configurations
There are a number of factors that will have a major influence on the
installation and performance of an earth energy or ground source heat pump
(GSHP) system. It is important for a homeowner to understand these issues.
The hot water and other options will all affect the operational efficacy
and efficiency, therefore it is very important to look at all options
during the design and selection process.
Dual Stage vs. Two Speeds
A dual system differs from what is commonly referred to as a two-speed
system in many specific ways. A two-speed system would be used for
instance when the cooling load is dramatically different than the heating
load or visa versa. Two-speed systems utilise the same compressor where a
two staged system uses two separate compression sections. A two Speed
System will operate very efficiently on low speed but when you switch to
high speed the efficiency will drop. Therefore sizing will be a much more
important factor with two speed systems. The benefit to using a Two Stage
or two separate compressors, is that the COP will be relatively equal
whether you are operating in stage one or both stages. A dual staged
system would commonly be used in a home where the heat loss is above
60,000 BTU. This would traditionally be a larger home in a very cold
climate or a very hot climate. In a climate where the heat loss and heat
gain are reasonably close to one another a single system would be used.
Dual Compressor Systems offer unparalleled efficiency because they can be
sized specifically to the heat loss and heat gain. For example, in a home
that has a heat loss of 90,000 BTU and a heat gain of 30,000 BTU, a two
staged system would be used to offer the total heat loss with both
compressors operating, then one compressor would be used for the cooling
mode. Although a dual system offers excellent efficiency and comfort
levels, the capitol cost is obviously higher, therefore, capitol cost vs.
efficiency and zoning must be considered at the design stage.
In-floor Heating & Hydronic Backup Hot Water Fan Coils
As stated in the Auxiliary/Emergency heat section, a "Hydronic Hot Water
Coil" is often employed where a customer has the opportunity to use hot
water directly from their domestic "quick response" hot water tank. Fuel
type is the key to help boost the heat output at times of very high
heating demand. Using a GSHP complete with a Hydronic Hot Water Coil as
backup is commonly referred to as a Dual Fuel System. An electric Hot
water tank would not be used in this application, except where a Demand
Hot Water Option has been built into the GSHP. An ODHW System is designed
to offer the homeowner a fully functional "quick response" hot water
system, which can be turned on and off based on the hot water demand. If a
hydronic fan coil or In-floor heating has been installed, along with an
ODHW, the ODHW would be the, highly efficient source of heat. If a
hydronic fan coil has been installed along with an independent quick
response hot water tank or boiler, that system would operate independent
to the Geothermal System.
An independent hydronic fan coil would be a system complete with a air
coil, pump and controls, hooked directly to the quick response hot water
system to offer heat to a given zone. For example, if a homeowner wants to
heat a garage to be used as a workshop sporadically, then the hydronic fan
coil would placed or hung in the garage space to offer heating only when
needed. Since under most building codes, the residential forced air system
cannot be ducted into the garage space because of fumes, etc, a hydronic
fan coil offers heat to such spaces without the need for extra ducting. A
hydronic air handler (air coil system with forced air) would simply take
water from the quick response hot water system and pass the hot water
through the hydronic coil. The independent fan would force air through the
coil causing the air to warm, offering a separate zone without the need
for zone controls.
In-floor systems generally operate on a zone by zone basis. For example it
is common to split an in-floor system so that individual room thermostats
call each zone. You could for example heat your garage floor with one zone
while heating your upstairs bathroom with another. Thereby independently
heating each zone while ensuring optimum comfort without sacrificing
efficiency. For more information on In-floor heating systems, please call
geoflex systems.
Open-Water or Open-Well
An open well system borrows water from a dug or a drilled well, then
directs the water through the GSHP system. Heat is then extracted from the
water in winter or rejected in summer, then the cooled/heated water is
returned to a pond, river, lake, weeping discharge pit or discharge well,
in accordance with local environmental regulations. Depending on the
location, the standard environmental "rule of thumb" is to return the
water that is utilized to the same aquifer level, at another point on the
same property, where the water was originally drawn. A Geothermal System
does nothing to negatively affect the water quality that it uses; it
absorbs or rejects heat only. The discharge system must be designed to
accommodate any locally sensitive environmental issues.
If the source of water is a lake, river or pond, the body of water must be
large enough to provide a sufficient "heat sink" capacity. Rivers can be
used as a source of water, but sources with high levels of salt, chlorides
or other minerals are not recommended for most units. Each
region/province/state has regulations concerning the use of water and if a
closed loop is used in the body of water, there are generally
laws/guidelines concerning the position of GSHP loops in navigable
waterways.
Water Quality
Open water systems depend on a source of water that is adequate in
temperature, flow rate and mineral content. A national Canadian
performance standard (CSA C446), rate GSHP Systems, based on their heating
efficiency when the entering water temperature is 10oC (0oC for closed
loop units). The output drops, when the entering temperature of water is
lower. Each GSHP model has a specified flow rate of water that is
required, and its output drops if this rate is reduced. The flow rate
required for cooling can be set much lower than for heating, since it is
much easier to reject heat than to absorb heat. The CSA installation
standard demands an official water well log to quantify a sustainable
water yield. Water for open-loop systems must be free of many contaminates
such as chlorides and metals, which can damage the heat exchanger of a
GSHP unit. Specially designed heat exchangers can be installed at the
manufacturing level, if there is a concern in regards to water quality.
Contact your manufacturer or installing dealer, if have a concern.
Water Discharge
There are environmental regulations, which govern how the water used in an
open-loop system can be returned to the ground. A return well is
acceptable, as long as the water is returned to the same aquifer or level
of water table. A discharge pit is also acceptable, as long as local
regulations and conditions are considered in the design.
Horizontal Closed Loops
 Horizontal loops are the most common configuration of closed loop systems
in North America. A trench is dug on the property and High Density,
Fusible, Polyethylene pipe is laid and appropriately spaced in the bottom
of the trench, then buried in a continuous or parallel loop (depending on
size of unit). The national Canadian installation standard (CSA C445)
states that the loop must be located at least 600 mm (2 feet) below
ground, but industry guidelines are at least twice that depth. The most
common depth is to bury a loop at least 300mm (1 foot) below the frost
level. It is possible to layer more than two pipes in each trench, thereby
reducing the cost of digging. If a double layer of pipe is used in a
single trench, then the trench must be deep enough to allow for thermal
separation. It is important to backfill the trench properly, to avoid air
pockets that can reduce the transfer of heat, and to ensure that the pipe
is not damaged by large sharp rocks.
Pond, River or Lake Loops
 A closed pond, river or "lake loop" system is positioned on the floor of a
body of water instead of being buried in the ground, as with a standard
horizontal loop. The pipe must be weighted properly to remain on the
bottom of the lake and to avoid shifting caused by spring ice movement. It
is common to attach the loop pipe to a non-polluting plastic mesh, such as
winter snow fencing, then floated out to the area of choice. This
configuration will create a loop grid as one circuit. The circuits are
then connected together to create one loop system, appropriately sized to
the installed system. When the loop is filled, it will sink to the bottom
of the lake, pond or riverbed. Weights are commonly attached to the top of
loop grid to hold them in position. Over a short period of time the
lakebed will cover the loop, creating a protective barrier and
aquaculture. Care must be taken to avoid harming the pre-existing
aquaculture. You should consider the positioning of the loop to avoid
areas that boats commonly anchor. An anchor can cause a loop to be moved
and or ruptured.
Vertical Closed Loops
 This is the most expensive type of closed loop but is a very efficient
configuration, due to the fact that the under-earth level of heat
increases and generally stabilizes with depth. It is also more than likely
that a drilled hole will pierce through an aquifer running water across
the loop on a regular basis, which helps to increase efficiency. This
option is viable when surface property is limited or has difficult
terrain. Care must be taken to ensure that the vertical bore holes are
drilled according to provincial/state/regional regulations.
Septic System and Your Loop
A common question is, "Can I install my loop close to my septic system to
take advantage of the heat that is going down my drain"? The answer is, it
is not wise to place your loop close to your septic bed. Although a
Geothermal System can easily take the heat away from the septic bed, a
septic bed requires heat to help with microbial action to break down the
sewage, which weeps from the system. If you take that heat away, the
microbial action can stop and you may harm your septic bed. Local building
codes will apply with this issue. There are methods to take advantage of
grey water heat but this application should be discussed with your local
building officials to ensure a proper system. A grey water re-capture
system would require two separate sewage systems within your home, one for
sewage and one for grey water.
Soil Type
Loose dry soil traps air and is less effective for the heat transfer
required in GHSP technology than moist packed soil. Each manufacturer
provides specifications on the relative merits of soil type;
low-conductive soil may require as much as 50% more loops than a quality
high-conductive soil. The more moisture, the better conductivity..
Type of Loop Pipe
The pipe that is most commonly used for GHSP installations is a high
density, polyethylene pipe. There would normally be two grades: "series
125" for residential installations, and "series 160" for commercial
installations. The pipe is heat fused at the time of installation to
eliminate any underground mechanical joints. When a pipe is properly heat
fused, the point of fusing is stronger than the pipe. Most loop pipe
manufacturers offer a 50-year warranty. GSHP pipe comes in three common
diameters: 0.75", 1" and 1.25". Two coiled loops (commonly called the "Svec
Spiral" and the "Slinky") require less trenching than conventional
straight pipe. As a result, the lower trenching costs and the savings in
property disruption offsets the higher cost of coiled pipe. The ground
overall mass required with straight verses the slinky pipe should be
approximately the same. Care must be used when back filling a slinky type
loop to ensure that pipes are spaced properly. In some cases a slinky loop
requires sand back filling around the loop pipe itself. Although straight
and slinky pipes are commonly used, the installing dealer will generally
install their preferred pipe size and type.
Loop Depth
GSHP technology relies on stable underground (or underwater) temperature
to function efficiently. In most cases, the deeper the loop is buried, the
more efficient the system. Normally a loop pipe will be buried
approximately 1 foot or 30 cm below the frost level. A vertical bore hole
is the most efficient configuration, but this type of drilling can be very
expensive.
Loop Length
The longer the amount of piping used in a GSHP outdoor loop, the more heat
that can be extracted from the ground (or water) for transfer to the
house. Installing less loop than specified by the manufacturer will result
in lower indoor temperature, and more strain on the system as it operates
longer to compensate for the demand. However, excessive piping can also
create a different set of problems, as well as additional cost. Each
manufacturer provides specifications for the amount of pipe required. As a
broad rule of thumb, a GSHP system requires 400 to 500 feet of horizontal
loop, or 300 to 350 feet of vertical loop to provide heat for each ton of
unit size.
Loop Spacing
The greater the distance between buried loops, the higher the efficiency.
Industry guidelines suggest that there should be 3 meters (10 feet)
between sections of buried loop, in order to allow the pipe to collect
heat from the surrounding earth without thermal interference from the
neighbouring loop. This spacing can be reduced under certain conditions.
It is common to bury one set of loops above another set with a deeper
trench. This would be covered under application designs. A rule of thumb
here would be, "more ground mass is always better than less".
Heat Transfer Fluids
Closed-loop GSHP units can circulate any approved "anti-freeze" fluid
inside the pipe, depending on the performance characteristics desired.
Each manufacturer must specify which fluids are acceptable to any
particular unit, with the most common being denatured ethanol or methanol
(the latter is not approved for use in Ontario, Canada because of the high
flash point).
Other Applications for GSHPs
With modifications, GSHP units can be used for the dehumidification of
indoor swimming pool areas, where the unit can dehumidify the air and
provide condensation control with a minimum of ventilation air. The heat
recovered from the condensed moisture is then used for heating
domestic/pool water or for space heating. Although this is an application
for GSHP systems, specific geoflex systems are more commonly used to
accomplish the goal of dehumidifying indoor poolrooms.
Efficient heating performance makes GSHP a good choice for the heating and
cooling of commercial and institutional buildings. Some examples of
commercial applications would include offices, stores, hospitals, hotels,
apartment buildings, schools, restaurants and larger government buildings.
GSHP systems heat water or heat/cool the interior space by transferring
heat from the ground outside, but they can also transfer heat within
buildings with a heat producing central core. Since GSHP technology
facilitates Energy Transfer, they can move heat from the core to the
perimeter zones where it is required, thereby simultaneously cooling the
core and heating the perimeter.
GHSP systems are also used as heat recovery devices to recover heat from
building exhaust air or from the wastewater of an industrial process. The
recovered heat is then supplied at a higher temperature at which it can be
more readily used for heating air or water.
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