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Questions and Answers provided by IGSHPA
Q: What effect would
increased use of GHP systems have on electricity cost and availability?
A: The reduced peak load
requirement would allow the utilities to serve more customers and to lower their
fixed costs per customer, thus offsetting some increased variable costs. This
would result in less cost per kilowatt, since fixed investment for new capacity
is high.
Q: What other costs
are there besides the GHP system?
A: You can expect an
installation charge for any electrical work, ductwork, water hook-up, and other
provisions or adaptations to your home that are required. These costs can be
estimated in advance by your installer.
Q: How effective is
this underground system?
A: The buried pipe, or ground
loop, is the most recent technical advance in heat pump technology. The idea to
bury pipe in the ground to gather heat energy began in the 1940s. Only recently,
however, have new heat pump designs and improved buried pipe materials been
combined to make GHP systems the most efficient heating and cooling systems
available.
Q: What are the
environmental benefits of GHP systems?
A: GHP systems conserve energy
and, because they move heat that already exists rather than burning something to
create heat, they reduce the amount of toxic emissions in the atmosphere. They
use renewable energy from the sun, and because the system doesn’t rely on
outside air, keeps the air inside of buildings cleaner and free from pollens,
outdoor pollutants, mold spores, and other allergens.
Q: Are GHP systems
difficult to install?
A: Most units are easy to
install, especially when they are replacing another forced-air system. This is
known as a retrofit. GHPs can be installed in areas unsuitable for fossil fuel
furnaces because there is no combustion and thus no need to vent exhaust fumes.
Ductwork must be installed in homes without an existing air distribution system.
The cost of installing ductwork can be assessed by your dealer or installer.
Q: Will my existing
ductwork function with this system?
A: Yes, in most cases. Your
dealer or installer will be able to determine ductwork requirements and minor
modifications needed, if any.
Q: Can I install an
ground heat exchanger myself?
A: It’s not recommended. In
addition to thermal fusion of the pipe, drilling and trenching are procedures
best handled by licensed professionals. Nonprofessional installations may result
in less than optimum performance, which could cancel out anticipated savings.
Q: How far apart are
trenches and vertical boreholes spaced?
A: Trenches are spaced four to
five feet apart while boreholes are spaced ten to fifteen feet apart.
Q: How long does it
take to install a horizontal system?
A: This depends on soil
conditions, length and depth of pipe, and equipment required. A typical
installation can be completed in one to two days.
Q: What changes in
performance can be expected at freezing operating conditions?
A: A drop in soil temperature
from 40°F to 30°F results in a loss of capacity and efficiency of about ten
percent. At 30°F, latent heat from moisture in the soil freezing adds
considerably to the capacity of the system, allowing very successful performance
of the systems in northern climates.
Q: Do soil freezing
conditions create any problems?
A: Not if a system is properly
designed and installed. The three to four foot depth allows the sun to melt the
frozen soil during the summer. Adequate length per ton capacity prevents
objectionable soil movement.
Q: How long does it
take to install a vertical system?
A: With the vertical
installation, time varies with conditions at the site such as type and depth of
the overburden, type and hardness of the bedrock, and the presence of aquifers.
Typical drilling times are one or two days; total installation can usually be
accomplished in two days.
Q: What are the
advantages and disadvantages of the horizontal and vertical installations,
respectively?
A: Horizontal installations
are simpler, requiring lower-cost equipment. However, they require longer
lengths of pipe due to seasonal variations in soil temperature and moisture
content. Since a horizontal heat exchanger is laid out in trenches, a larger
area is usually required than for a vertical system. Where land is limited,
vertical installations or a compact Slinky™ horizontal installation can be
ideal. If regional soil conditions include extensive hard rock, a vertical
installation may be the only available choice. Vertical installations tend to be
more expensive due to the increased cost of drilling versus trenching, but since
the heat exchanger is buried deeper than with a horizontal system, vertical
systems are usually more efficient and can get by with less total pipe. Your GHP
contractor will be able to help you decide which configuration best meets your
specific needs.
Q: How can I be sure
the pipe is installed properly?
A: Use a reputable contractor.
Don’t be afraid to ask for and use references. Reputable dealers and loop
installers will be happy to give names and phone numbers for you to call and
confirm their capabilities. Find out where the installer received training,
whether he or she is IGSHPA-trained, and how many systems he or she has
installed. Also, check with your utility company representative for names of
installers. IGSHPA will provide a list of IGSHPA-trained installers in your area
upon request.
Q: Will an underground
loop affect my lawn or landscape?
A: No. Research has shown that
loops have no adverse effects on grass, trees, or shrubs. Most horizontal
installations require trenches about six inches wide. Temporary bare areas can
be restored with grass seed or sod. Vertical loops require little space and do
not damage lawns significantly.
Q: My yard contains
many shade trees. Will this affect ground temperature and my ability to use it
as an energy source?
A: Not at all.
Q: Will I have to add
insulation to my home if I install one of these systems?
A: Geothermal heat pump
systems will reduce your heating and cooling costs regardless of how well your
home is insulated. However, insulating and weatherizing are key factors in
gaining the maximum amount of savings from any type of heating and cooling
system.
Q: Can these systems
be used for commercial, industrial, or apartment requirements?
A: Yes. Many GHP systems are
being installed using a multitude of systems hooked up to an array of buried
vertical or horizontal loops. This simplifies zone control and internal load
balancing.
Q: How does a GHP
system heat water for my home?
A: Using what is called a
desuperheater, GHPs turn waste heat to the task of heating hot water. During the
summer, when the system is in a cooling mode, your hot water is produced free as
a byproduct of the thermal process. In winter, with the heating mode, the
desuperheater heats a portion of your hot water. Desuperheaters are standard on
some units, optional on others. Stand-alone systems which will heat water all
year around can be purchased.
Q: Can a GHP system be
added to my fossil fuel furnace?
A: Yes. Called dual systems, they can
easily be added to existing furnaces for those wishing to have a dual-fuel
heating system. Dual-fuel systems use the GHP system as the main heating source,
and a fossil fuel furnace as a supplement in extremely cold weather should
additional heat be needed.
Q: Does this mean that
in extremely cold climates additional heat sources are necessary?
A: All systems require an
emergency back-up. Heat pumps can provide all the heat necessary even in the
coldest weather. An economic analysis by your contractor should dictate what
portion of the heat should be provided by the heat pump and which by auxilary
means.
Q: Is it advisable to
install a GHP system large enough to handle my total heating needs?
A: Your dealer/installer
should provide a heating and cooling load calculation to guide your equipment
selection. GHP systems are generally sized to meet all your cooling needs.
Depending on heating needs, a GHP system usually supplies 80–100 percent of
your design heating load. Sizing the system to handle your entire heating needs
may result in slightly lower heating costs, but the savings may not offset the
added total of the larger system. Special consideration should be given to
systems in the north where multiple capacity units should be considered to
handle the large variation between heating and cooling loads.
Q: Are GHP systems
guaranteed?
A: Nearly all GHP system
manufacturers offer a warranty for major components that is equivalent to the
warranties for conventional heating and cooling systems. Manufacturers of
plastic pipe used for ground loops warrant their products for 25–50 years.
Q: What about comfort?
A: A GHP system moves warm air
(90–105°F) throughout your home or business via standard ductwork. An even
comfort level is created because the warm air is moved in slightly higher
volumes and saturates the building with warmth more evenly. This helps to even
out hot or cold spots and eliminates the cold air blasts common with fossil fuel
furnaces.
Q: What are the
advantages to an HVAC dealer?
A: GHP systems create a huge
retrofit market not subject to wild fluctuations in housing construction. There
is also ample opportunity for stable growth benefiting the dealer and his
employees. In addition, these systems are relatively maintenance-free, requiring
only regular filter changes. This means fewer maintenance and support calls.
There is no outside equipment, so wear and tear is less.
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