• ASHRAE: American Society for Testing Materials

• ASTM:  American Society for Testing and Materials

• Bend:  A fitting either molded separately or formed from pipe for the purpose of accommodating a directional
                change. (IGSHPA)

• Bentonite:  A highly plastic, colloidal clay composed largely of mineral montmorillonite.

• British Thermal Unit (Btu):  The quantity of heat required to raise the temperature of one pound of water one
                degree Fahrenheit at a specified temperature.

• Closed Loop System:  In a ground-coupled system, a pressurized heat exchanger consisting of the ground
                heat exchanger, the circulating pump, and the water-source heat pump in which the heat transfer fluid is
                not exposed to the atmosphere.  (IGSHPA)

• COP:  Coefficient of Performance (COP) is the ratio of heat provided in Btu per Btu of energy input.

• Drilling Mud:  A fluid composed of water and Bentonite used in the drilling (primarily rotary) operation to
                remove cuttings from the hole, to clean and cool the bit, to reduce friction between the drill stem and the
                sides of the hole, and to plaster the sides of the hole.  Such fluids range from relatively clear water to
                carefully prepared mixtures of special purpose compounds. 

• EER:  Energy Efficiency Ratio (EER) is the ration of heat removed (in Btu per hour) to the electricity required (in
                watts) to run the unit.

• Fitting:  A piping component used to join or terminate sections of pipe or to provide changes of direction or
                branching in a pipe system.  (IGSHPA)

• Flush Cart: See Purge Pump

• Fuse:  To make a plastic pipe join by heat and pressure.  (IGSHPA)

• Ground-Coupled Heat Pump:  A heat pump that uses the earth itself as a heat source and heat sink.  It is
                coupled to the ground by means of a closed-loop heat exchanger installed horizontally or vertically
                underground.  (IGSHPA)

• Grout:  A high solids fluid mixture of cement or Bentonite and water of a consistency that can be forced through
                a pipe and placed as required.  Various additives, such as sand, Bentonite, and hydrated lime, are
                included in the mixture to meet certain requirements.  For example, sand is added when a considerable
                volume of grout is needed.

• Grouting (positive emplacement):  A technique of installation of grouting materials whereby emplacement is
                achieved by positive pressure extended from the bottom of the zone upward via a grout pipe extending
                from the surface.

• Heat Exchanger:  A device specifically designed to transfer heat between two physically separated fluids of
                different temperatures.  (IGSHPA)

• Heat Joining:  Making a joint by heating the mating surfaces of the pipe components to be joined and pressing
                them together so that they fuse and become essentially one piece.  (IGSHPA)

• Heat Pump:  A mechanical device used for heating and cooling which operates by pumping heat from a cooler
                to a warmer location.  (IGSHPA)

• Heat Sink:  The medium - air, water, earth, etc. - which receives heat from a heat pump.  (IGSHPA)

• Joint:  The location at which two pieces of pipe or a pipe and a fitting are connected.  (IGSHPA)

• Joint, Butt-Fused:  A joint in which the prepared ends of the joint components are heated and then placed in
                contact to form a joint.  (IGSHPA)

• Joint, Heat-Fused:  A joint made using heat and pressure only.  There are three basic types of heat-fused
                joints: butt-fused, socket- or insert-fused, and saddle-fused.  (IGSHPA)

• Joint, Socket-Fused:  A joint in which the two pieces to be heat fused are connected using a third coupling or
                fitting with a female end.  (IGSHPA)

• Parallel System:  A flow condition where two or more fluid paths are possible in the closed-loop circuit. 
                (IGSHPA)

• Permeability:  A measure of the relative ease with which a porous medium can transmit a liquid under a
                potential gradient.  It is a property of the medium alone and is independent of the nature of the liquid and
                of the force field causing movement.  It is a property of the medium that is dependent upon the shape
                and size of the pores.

• Polymer:  A substance consisting of molecules characterized by the repetition of one or more tyupes of
                monomeric units.  (IGSHPA)

• Potable Water:  Water suitable for human consumption.

• Pressure:  When expressed with reference to pipe, the force per unit area exerted by the medium in the pipe. 
                (IGSHPA)

• Pressure Drop:  The decrease in pressure down the length of a pipe resulting from fluid flow.  (IGSHPA)

• Pressure Rating:  The estimated maximum pressure that the medium in the pipe can exert continuously with a
                high degree of certainty that failure of the pipe will not occur.  (IGSHPA)

• Purge Pump/Flush Cart:  A high-pressure and high flow-rate pump used to flush air and debris from closed-
                loop circuit of a closed-loop/ground source heat pump system.  (IGSHPA)

• Schedule:  A pipe size and wall thickness classification system (outside diameters and wall thickness). 
                (IGSHPA)

• SEER: Seasonal Energy Efficiency Rating - Used for rating air to air heat pumps.  The higher the number, the
                better the efficiency of the unit.

• Soil/Field Resistance:  The resistance to heat flow resulting from soil thermal properties and underground pipe
                placement.  (IGSHPA)

• Standard Dimension Ratio (SDR):  A specific ratio of the average specified outside diameter to the minimum
                specified wall thickness (OD/t) for outside-diameter controlled plastic pipe.  (IGSHPA)

• Test Hole:  Hole designed to obtain information on ground water quality and/or geological and hydrological
                conditions, as well as heat transfer characteristics.

• Transmissivity:  The rate at which water of the prevailing kinematic viscosity is transmitted through a unit width
                of an aquifer under a unit hydraulic gradient.

• Tremie Pipe:  A device, usually a small diameter pipe, that carries grouting materials to the bottom of the hole. 
                Can be used to allow pressure grouting from the bottom up without introduction of appreciable air
                pockets.

• U-bend:  A prefabricated closed-return pipe assembly used in vertical heat exchangers to connect the two
                pipes at the bottom of the borehole.  (IGSHPA)

• Vertical Closed Loop Borehole:  A vertical closed loop borehole for which the hole is generally excavated by
                mechanical means such as the rotary or cable tool methods.

• Water-Source Heat Pump:  A heat pump that uses a water-to refrigerant heat exchanger to extract heat from
                the heat source.  (IGSHPA)

• Water-Source Heat Pump, Closed Loop:  Closed-loop systems circulate a heat transfer fluid (such as water
                or a water-anti-freeze mixture) continuously to extract or reject heat from a ground or water heat source
                or sink.  (IGSHPA)

• Zone of Aeration:  The zone above the water table in which the interstices are partly filled with air.  The term is
                replaced by "unsaturated zone."  It includes the capillary fringe.

• Zone of Saturation:  The zone below the water table in which all interstices are filled with ground water. 

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