A Copper Alliance Member
New ARI Standard Published for Testing and Rating Direct-Exchange Geothermal Heat Pump
January 14, 2000
FOR IMMEDIATE RELEASE
D/X Installations Gaining Momentum with Passage of New Standard
NEW YORK— Direct-exchange geothermal heating
and cooling systems have been around for more than a decade.
However installations are likely to increase significantly now
that the
Air Conditioning and Refrigeration Institute (ARI) has approved
a new standard for such systems. The new standard establishes
definitions and requirements for testing and rating direct geoexchange
heat
pumps. The recent approval of ARI 870: Direct Geoexchange Heat
Pumps means that direct-exchange systems will be independently
tested and monitored to meet strict operating and safety requirements.
Ultimately the test data and rating information that result from
the new ARI standard will allow meaningful comparisons of direct
geoexchange system performance data with those of other heating
and cooling systems.
Copper Tube is Key to Success of D/X GCH Systems
Direct-exchange geothermal systems use the earth as an energy
reservoir, taking advantage of the constant temperature (about
55°F) 4 feet below
the surface. Copper tubes run underground carry refrigerant that circulates
into and out of a home. A compressor induces heat exchange, and heated
or cooled air is distributed through an air handler.
The heat-transfer medium in geothermal systems always enters a home at
the ambient below-grade temperature, unlike other systems in which the
heat-transfer medium is exposed to much hotter or colder outside air temperatures.
Once the refrigerant reaches the heat pump, which is situated inside the
home, the compressor concentrates and delivers the heat.
To increase efficiency further in the air-conditioning season, waste heat
can be transferred to the water heater. Research indicates that geothermal
systems reduce heating and cooling costs by an average of 30 to 60 percent
when compared to air-source heat pumps.
Direct-exchange geothermal heating and cooling systems are generally regarded
as energy efficient and inexpensive to operate because they burn no fuel
and consume no energy beyond the electricity required to operate the compressor
and the fan used to circulate the air.
Benefits of D/X Systems vs. Water-based Geothermal Systems
What sets direct-exchange systems apart from other geothermal systems is
the fact that only one transfer is required for heat exchange, compared
to the two steps required in water-based systems. The copper tube used
in direct-exchange systems is an excellent heat conductor-much more efficient
than the plastic tubes used in water-based systems. This conductivity enables
copper systems to work more efficiently and with smaller-diameter tubes
than those used in plastic systems, so bore holes are smaller, reducing
excavation and installation costs.
Manufacturers of direct-geoexchange heat pumps include: ECR Technologies, Inc., P.O. Box 3271, Lakeland, Fl 33802, phone: (941) 688-0880, and American Geothermal DX TM, 1037 Old Salem
Road, Murfreesboro, Tennessee 37129-4936, phone: (615) 890-6985.
[Note: Further information and a case study documenting the installation
of a direct-exchange geothermal heat-pump system at a Pennsylvania home
site can be viewed by visiting the our Heat Pump section. Photos
of the installation can be obtained by calling either of the contacts listed
on the first page of this release.]
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