These
are some common questions and answers regarding geothermal
(or GeoExchange) systems. Please visit the other sections
of Learn More for more detailed answers.
How
does a GeoExchange system work?
Throughout
the year, outdoor temperatures fluctuate with the changing
seasons. However, underground temperatures do not. In fact,
about four to
six feet below the earth's surface, temperatures remain relatively
constant
year-round. A GeoExchange system, which consists of an indoor
unit and a
buried earth loop, capitalizes on these constant temperatures.
In the winter,
fluid circulating through the system's earth loop absorbs
stored heat and
carries it indoors. The indoor unit compresses the heat to
a higher
temperature and distributes it throughout the building. In
the summer, the
system reverses, pulling heat from the building, carrying
it through the earth
loop and depositing it in the cooler earth.
What makes
a GeoExchange system different from conventional
systems?
A GeoExchange
system utilizes the energy from the sun which is stored
in the earth to heat and cool homes and buildings. Typically,
electric power
is used only to operate the unit's fan, compressor and pump.
So, unlike
conventional systems, GeoExchange systems do not burn fossil
fuel to
generate heat -- they simply transfer heat to and from the
earth.
How
efficient is a GeoExchange system?
A
GeoExchange system is more than four times as efficient as
the
most efficient conventional system. Because GeoExchange systems
do not
burn combustible fuel to make heat, they provide three to
four units of
energy for every one unit used to power the system.
How
do GeoExchange systems affect the environment?
Because GeoExchange systems work with nature, not against
it, they
help to reduce acid rain, air pollution and the greenhouse
effect.
An environmentally friendly fluid is used in the closed, continuous
loop. The latest geothermal heat pump units use environmentally
friendly refrigerant as well (see the equipment section).
Do
GeoExchange systems require much maintenance?
No.
In fact, GeoExchange systems are practically maintenance free.
When installed properly, the buried loop will last for generations.
And the
other half of the operation -- the unit's fan, compressor
and pump -- is housed
indoors, protected from the outdoors. Usually, periodic
checks and filter changes are the only required maintenance.
Is
the efficiency rating actual or just a manufacturer's average?
All
types of heating and cooling systems have a rated efficiency.
Fossil
fuel furnaces have a percentage efficiency rating. Natural
gas, propane and
fuel oil furnaces have efficiency ratings based on laboratory
conditions. To
get an accurate installed efficiency rating, factors such
as gas heat
losses, cycling losses caused by oversizing, blower fan electrical
usage, etc.,
must be accounted for. Geothermal heat pumps, as well as all
other types of heat
pumps, have efficiencies rated according to their coefficient
of performance
or COP. It's a scientific way of determining how much energy
the system
produces versus how much it uses. Most geothermal heat pump
systems
have COPs of 2.5 - 3.5, and the new Envision series has a COP of 5.0. That means for every one unit of energy
used to
power the system, two and one-half to five units
are supplied
in return as heat (depending on equipment). Where a fossil fuel furnace may be 50-92
percent efficient at most, a geothermal heat pump is more
than 300 percent efficient. Some geothermal
heat pump manufacturers and electric utilities use computers
to accurately
determine the operating efficiency of a system for your home
or building.
Are
the dealer and loop installers qualified?
Don't be afraid to ask for references from dealers. A reputable
dealer
won't hesitate to give you names and numbers to call to confirm
his
capabilities. The same applies to the loop installer.
How
long is the payback period for your geothermal heat pump system?
To figure this accurately, you must know how much per year
you'll save in
energy costs with a geothermal system and the difference in
costs between
it and a conventional heating system and central air conditioner.
For
example: If you'll save $1000 per year with a geothermal system
and the
cost difference is about $3,000, your payback will be less
than three
years. If you install a geothermal system in a new home, the
monthly
savings in operating costs will generally offset the additional
monthly cost in
the mortgage, resulting in a monthly positive cash flow immediately.
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