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Absolute Humidity
Amount of moisture in the air, indicated in grains per cubic foot.

Active Cooling
Compressor driven air-conditioning.

Air Washer
Device used to clean air, which may increase or decrease humidity.

Instrument for measuring the rate of flow of air.

A large body of underground water.

Decrease or lessen in intensity.


Plate or vane used to direct or control the movement of fluid or air within a confined area.

BTU (British Thermal Unit)
The amount of heat required to raise the temperature of one pound of water, one degree Fahrenheit.

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Carbon Filter
Air filter using activated carbon as an air cleaning agent.

Cubic feet per minute of air flow.

Check Valve
A check valve is a mechanical device normally applied to a piping system which allows fluid to flow in only one direction.

Closed Loop
An underground heat exchanger piping system usually of polyethylene or polybutylene designed to allow the extraction or rejection of heat to the earth by the circulation of fluid within the tubing.

Coefficient of Performance (COP)
Heating capacity divided by electrical energy consumed. ( e.g.15 kW output / 4.5 kW input = COP of 3.3) The coefficient of performance of a heating system is the electrical ratio of the heat we get out divided by the heat we put in.

Comfort Zone
Area on the psychrometric chart that shows conditions of temperature, humidity, and sometimes air movement in which most people feel comfortable.

A refrigeration component which increases the density, temperature and pressure of entering refrigerant through compression and discharges a hot dense gas.

The heat rejecting mechanism in a heat pump usually in the form of a refrigerant-to-air coil or a refrigerant-to-water coil. Refrigeration heat exchanger where the refrigerant gives up its heat during condensation from a vapour to a liquid.

Condenser Types
air-cooled and water-cooled. An air-cooled condenser is a heat exchanger that transfers heat to the surrounding air. A water-cooled condenser is a heat exchanger that transfers heat from a hot gaseous refrigerant to water.

Critical Vibration
Vibration that is noticeable and harmful to a structure.

90% copper / 10% nickel alloy which has high corrosion resistance to water containing salt, sulphur, chlorides and other dissolved minerals.


Device for controlling air flow.

Unit used for the measuring the relative loudness of sounds. One decibel is equal the approximate difference of loudness ordinarily detectable by the human ear, the range of which is about 130 decibels on a scale beginning at one, for the faintest audible sound

Degree Day
The number of degrees that the mean temperature for that day is below 65° F. (eg. mean temp. of 40° F for the day--65-40=25 degree days)

Device used to remove moisture from the air in an enclosed place.

A heat exchanger and pump system which removes a small portion of heat from the compressor discharge gas and typically transfers it to a domestic hot water tank.

Temperature at which vapour (at 100 percent humidity) begins to condense and deposit as liquid.

Direct Expansion Heat Pump
A geothermal heat pump system whereby the liquid refrigerant is sent directly out into copper coils buried in the ground where it is vaporised or condensed by contact with the earth.

Drip Pan
Pan-shaped panel or trough used to collect condensation from an evaporator coil.

Dry Bulb
An instrument with a sensitive element that measures ambient (moving) air temperature.

Dual Condenser
A heat pump system that has the capability to switch, usually automatically, between an air and a water heat exchanger. Full capacity hot air or hot water output is available.

A tube or channel through which air (heated or air-conditioned) is conveyed or moved.

Device for measuring power input or output of a mechanism.

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Effective Temperature
Overall effect on a human of air temperature, humidity and air movement.

Electrostatic Filter
A filter that gives particles of dust an electric charge. This causes the particles to be attracted to a plate so they can be removed from the air-stream or atmosphere.

Energy Efficiency Ratio (EER)
Cooling capacity in BTU/hr divided by electrical energy consumed in watts.

Entering water or fluid temperature.

The term applied to the changing of a liquid to a gas. Heat is absorbed in the process

The heat absorbing mechanism or heat exchanger in a heat pump. Refrigerant changes state from a liquid to a gas in this exchanger, absorbing heat energy from the surrounding media in the process.

Expansion Valve
A device in a refrigerating system that reduces and maintains a pressure difference between the "high side" and "low side" operated by pressure.

Exergy expresses the quality of an energy source and quantifies the useful work that may be done by a certain quantity of energy.

Combining geothermal heating and cooling with the best use of available energy can create an integrated, efficient and cost-effective solution for your project while helping you meet your environmental goals.

The "exergy" content required to satisfy the demands for heating and cooling of buildings is very low, since a room temperature of 20?C (68?F) is fairly close to the ambient conditions. Nevertheless, high quality energy sources like fossil fuels are commonly used to satisfy these small demands for exergy.


A radial or axial flow device used for moving or producing artificial current air.

Flash Gas
Instantaneous evaporation of some liquid refrigerant in the evaporator, which cools the remaining liquid refrigerant to the desired evaporation temperature.

Flow Meter
Instrument used to measure the velocity or volume of fluid movement.

Forced Air
A heating/cooling system that uses a fan to circulate air or cause air flow.

Freezing Point
Temperature at which a liquid will solidify upon the removal of heat. The freezing temperature for water is 32 degrees Fahrenheit (zero degrees Celsius).

Trade name for a series of man made chemicals or refrigerants used in refrigeration systems. Each refrigerant is designed to change phase at specific temperatures and pressures that will produce the desired cooling effect required for a specific job. The refrigerant absorbs energy as it evaporates and releases energy during condensation.

Frost back
Condition in which liquid refrigerant flows from the evaporator into the suction line; usually indicated by sweating or frosting of the suction line.

Full-Condensing Heat Exchanger
A heat exchanger with enough surface area to condense all the hot refrigerant gas produced by a heat pump to its liquid state thereby transferring the all the heat produced by the unit.

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Geothermal Energy
Heat energy stored in the earth's crust by the absorption of solar energy and by conduction with the earth's hot interior. This underground or underwater temperature source is used for the operation of a heating and cooling system - heat pump

Geothermal Heat pump
A heat pump that uses the constant underground or underwater temperatures as supply.

Ground Loop
A series of heat exchange pipes containing an antifreeze solution buried either vertically or horizontally in the earth.

Ground Source
A heat pump that utilises the earth as it's source of energy.


Heat Exchanger
A component or components that transfers heat energy from one medium to another. For example heat could be transferred, in a geothermal heat pump system, from water-to-air or from water-to-water and visa versa.

Heat Load
Amount of heat, measured in BTU's, that is removed during a 24 hour period.

Heat Loss
A measure of the amount of heat that escapes from a material or substance, measured in BTU's for hours.

Heat Recovery System
Produces and stores hot water by transferring heat from a condenser to cooler water

Heat Source
The area or media from which heat is removed. (water, air, etc.)

Heat Sink
The area or media to where heat is deposited. (For instance, inside a home.)

Heat transfer
Movement of heat from one body or substance to another. Heat may be transferred by radiation, conduction, convection or a combination of these three methods.

An electrical control that is operated by changing humidity.

A complete unitary system which is commonly designed to offer two types of fuel sources, for example a system which will use your swimming pool as a heat rejection point for A/C, virtually dobling your efficiency and an air handler to take water out of your hot water tank for heating, both systems would be in one cabinet.

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Kilowatt-hours, an electrical term where 1 kWh equals the use of 1000 watts for one hour.


Liquid-to-Air Heat Pump
A heat pump that absorbs heat from a liquid and distributes the energy in the form of hot forced air. (Generally called Water to Air Heat Pump)

Liquid-to-Liquid heat pump
A heat pump that absorbs heat from a liquid and distributes the energy in the form of hot water. (Generally called a Water to Water Heat pump)


Mechanical Cooling
Conventional cooling provided by a compressor operated refrigeration device. Term can be interchanged with "active cooling".

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Open Loop
A system where water is pumped from a water well, pond, lake or other surface source for use in a heat pump.

Oversized Evaporator
A technique of employing a larger than normal evaporator (heat absorption device) in a geothermal heat pump in order to obtain greater heat exchange and thus better performance from the unit.


assive Cooling
A process whereby cold well water (less than 50° F.) is pumped directly to a finned air coil (much like the radiator of a car) so that when the heat pump fan is operated, cooling and dehumidification are provided without the operation of a compressor driven refrigeration system.

Package Heat Pump
A heat pump that has all components (compressor, blower and heat exchangers etc.) in one cabinet.

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Rankin Scale
Name given to the absolute (Fahrenheit) scale. Zero () degrees Rankin) on this scale is -460 degrees Fahrenheit

A naturally occurring or man made liquid which absorbs and releases heat energy in a refrigeration device by changing phase from a liquid to a gas and visa versa in response to the influence of a refrigeration compressor.

Refrigerant Charge
Quantity of refrigerant in a system

Relative Humidity
Ratio of (difference between) the amount of water vapour present in the air to the greatest amount possible at the same temperature.

Reversing Heat Pump
A heat pump in which the condenser and evaporator coils of the unit reverse roles in response to a reverse in the direction of the flow of refrigerant in the machine

Reversing Valve
Device used to reverse the direction of the refrigerant flow, depending upon whether heating or cooling is desired

Radiant Floor Heating
Process of embedding tubing (cross-linked polyethylene, polybutylene etc.) directly in a concrete floor so that hot water can be pumped through the tubing for the purpose of heating the floor and thus the building.

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Seasonal Coefficient of Performance (SCOP)
The average COP over the entire heating season.

Seasonal Energy Efficiency Ratio (SEER)
The average cooling efficiency over an entire cooling season.

Simple Pay back Factor (heating)
Subtract the installation cost of the least expensive (less efficient) system from the installation cost of the more expensive (more efficient) heating system. This value is the increased cost of installing the more efficient system. Calculate the yearly energy savings in dollars by installing the more efficient system. Take the increased cost to install divided by the yearly energy savings and your result is the number of years required for the more efficient system to pay for itself.

Sink Temperature
This is the temperature of the media (water or air) into which the heat pump must reject it's heat.

Source Temperature
This is the temperature of the media (water or air) from which the heat pump extracts its heat.

Split System
Split heat pumps are two (2) part refrigeration systems which have separate evaporator / air handler and compressor / condenser sections. Commonly employed in air-to-air systems where the condenser section is located outside the home while the evaporator / air handler is located inside the conditioned structure.

Suction Line
Tube or pipe used to carry refrigerant gas from evaporator to compressor

Suction Side
The Low-pressure side of the system extending from the refrigerant control through the evaporator to the inlet side of the compressor

Super Heat
1) Temperature of a vapour above it's boiling temperature as a liquid at that pressure. 2) The difference between the temperature at the evaporator outlet and the lower temperature of the refrigerant evaporating in the evaporator.

Heat exchanger arranged to take heat from liquid going to the evaporator and use it to superheat vapour leaving the evaporator


TX Valve
Thermo Expansion Valve A temperature and pressure controlled device for metering refrigerant in a heat pump or other refrigeration device. Also known as a "TEV"

Ton (of refrigeration)
The amount of energy it takes to convert 2000 lbs. of water at 32° F. to ice at 32° F. during a 24 hour period. Calculation: 2000 lbs. (H2O) x 144 Btu/lb. = 288,000 Btu's in 24 Hrs. Divide by 24 hrs = 12,000 Btu/hr. Therefore a "ton" of cooling is a measure of heat energy which is roughly equivalent to 12,000 BTU's.

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Water Well
A vertical hole drilled into the earth´s crust usually to a depth of less than 300 ft. for the purpose of accessing an underground water supply (aquifer). A pumping system generally of the submersible type is normally installed to bring the water to the surface under sufficient pressure to be used in a home.

A heat pump which extracts heat from water in one area and transfers the heat usually at a higher temperature to another body of water. E.g. Extracting heat from a 50° F. well and using it to heat domestic hot water at 120° F.

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Zone Controls
Controls used to maintain each specific area or zone within a building at a desired condition. This is a type of distribution control often used in a hydronic heating system.

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