Closed loop systems should be
installed using only high-density polyethylene pipe. Properly installed, these
pipes can outlast the house. They are inert to chemicals normally found in soil
and have good heat conducting properties. PVC pipe should never be used.
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Trenches are normally four to
six feet deep and up to 400 feet long, depending on the number of pipes in a
trench. One advantage of a horizontal loop system is being able to lay the
trenches according to the shape of the land. As a rule of thumb, 500-600 feet
of pipe is required per ton of system capacity. A well-insulated 2,000
square-foot home would need about a three-ton system with 1,500-1,800 feet of
pipe.
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Pipe sections are joined by
thermal fusion. Thermal fusion involves heating the pipe connections and then
fusing them together to form a joint that’s stronger than the original pipe.
This technique creates a secure connection to protect from leakage and
contamination.
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Yes, if it’s deep enough and
large enough. A minimum of six feet in depth at its lowest level during the
year is needed for a pond to be considered. The amount of surface area required
depends on the heating and cooling loads of the structure. You should opt
against using water from a spring, pond, lake or river as a source for an open
loop system unless it’s proven to be free of excessive particles and organic
matter. They can clog a heat pump system and make it inoperable in a short
time.
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It’s not recommended. Good
earth-to-coil contact is very important for successful loop operation.
Nonprofessional installations may result in inefficient system performance.
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Closed loop systems also can
be vertical. Holes are bored up to 250 feet per ton of heat pump capacity,
depending on where you live. U-shaped loops of pipe are inserted in the holes.
The holes are then backfilled with a sealing solution.
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Don’t be afraid to ask for
references from dealers. A reputable dealer or loop installer won’t hesitate to
give you names and numbers to call to confirm his capabilities.
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Split systems can easily be
added to existing furnaces for those wishing to have a dual-fuel heating
system. Dual-fuel systems use the heat pump as the main heating source and a
fossil fuel furnace as a supplement in extremely cold weather if additional
heat is needed.
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Most units are easy to
install, particularly when they replace another forced-air system. They can be
installed in areas unsuitable for fossil fuel furnaces because there is no
combustion, thus no need to vent exhaust gases. Ductwork must be installed in
homes that don’t have an existing air distribution system. The difficulty of
installing ductwork will vary and should be assessed by a contractor. Another
popular way to use geothermal technology is with in-floor radiant heating, in
which hot water circulating through pipes under the floor heats the room.
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In all probability, yes. Your
installing contractor should be able to determine ductwork requirements and any
minor modifications if needed.
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Not always. It may be
desirable to install geothermal heat pump room units. For some small homes, a
one-room unit would handle the heating and cooling needs. Ceiling cable or
baseboard units could be used for supplemental heat if desired.
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Geothermal heat pumps don’t
use large amounts of resistance heat so your exsisting service may be adequate.
Generally, a 200-amp service will have enough capacity and smaller amp services
may be large enough in some cases. Your electric utility or contractor can
determine your service needs.
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Furnaces are designed to
provide specific amounts of heat energy per hour. The term ”BTUH” refers to how
much heat can be produced by the unit in an hour. Before you can determine what
size furnace you’ll need, you must have a heat loss/heat gain calculation done
on the structure. From that, an accurate determination can be made of the size
of the system you’ll need. Most
fossil fuel furnaces are substantially oversized for heating requirements,
resulting in increased operating cost and unpleasant temperature swings.
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Your contractor should
provide a heating and cooling load calculation (heat loss, heat gain) to guide
yoru equipment selection. Geothermal heat pumps typically are sized to meet
your cooling requirements. Depending on your heating needs, a geothermal heat
pump will supply 80-100 percent of your design heating load. Sizing the heat
pump to handle your entire heating needs may result in slightly lower heating
costs, but the savings may not offset the added cost of the larger heat pump
unit and larger loop installation. Also, an oversized unit can cause
dehumidification problems in the cooling mode, resulting in a loss of summer
comfort.
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Geothermal systems are so
energy-efficient that the payback period is remarkably brief. A study by the
Air Force Institute of Technology calculated that it takes on average just
seven to eight years to recoup costs.
Your specific payback point
depends on factors like local utility rates, excavation/drilling costs, how
well your house is insulated, the efficiency of the model you choose, and what
incentives your state or utilities provide.
One of the best aspects about
geothermal is cash flow. If you install a geothermal system, the monthly
savings in operating costs generally offset the additional monthly financing
cost, resulting in an immediate positive cash flow – especially in a new home.
Again, your specific situation may vary.
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