Commonly Used Terminology in Geothermal Heating and Cooling
&Cooling
Aquifer - A large body of underground water.
Active Cooling - Compressor driven air-conditioning.
Amps - Current (back up excluded)
BTU - British Thermal Unit - The amount of heat required to raise the
temperature of one pound of water, one degree Fahrenheit.
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.
Condenser - 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 vapor to
a liquid.
Compressor - Refrigeration component which increases the density, temperature
and pressure of entering refrigerant through compression and discharges a hot dense
gas.
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.
Check Valve - A check valve is a mechanical device normally applied to a
piping system which allows fluid to flow in only one direction.
CFM - Cubic feet per minute of air flow.
Cupro-nickel - 90% copper / 10% nickel alloy which has high corrosion
resistance to water containing salt, sulphur, chlorides and other dissolved
minerals.
Cond. - Freon temperature on condenser side.
Comp.-Wats - Compressor electricity consumption.
Degree Day - The number of degrees that the mean temperature for that day is
below 65 degrees F. (e.g. mean temp. of 40 degrees F for the day--65-40=25 degree
days)
Desuperheater - 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.
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
vaporized or condensed by contact with the earth.
Dual Condenser - A heat pump system which 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.
Delta T. - Difference in-between LWT and EWT
Energy Efficiency Ratio (EER) - Cooling capacity in BTU/hr divided by
electrical energy consumed in watts.
EWT - Entering water or fluid temperature.
ELT - Entering liquid temperature.
EAT - Entering air temperature.
EER - Energy efficiency ratio.
Evaporator - The heat absorbing mechanism or heat exchanger in a heat pump.
Refrigerant changes phase from a liquid to a gas in this exchanger, absorbing heat
energy from the surrounding media in the process.
Evap. T. - The temperature on evaporator side when Freon is converted from a
liquid to a vapor (gas)
Freon - 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 which will produce the desired cooling effect required for
a specific job. The refrigerant absorbs energy as it evaporates and releases energy
during condensation.
Full Package - Self contained heat pump which has blower and compressor
section integrated into one unit.
Full-Condensing Heat Exchanger - A heat exchanger with enough surface area to
condense all the hot refrigerant gas produced by a heat pump to it's liquid state
thereby transferring the all the heat produced by the unit.
Flow IGPM - Liquid flow.
Fan-Watts - Blower motor electricity consumption.
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.
Ground Loop - A series of heat exchange pipes containing an antifreeze
solution which are buried either vertically or horizontally in the earth.
Ground Source - A heat pump which utilizes the earth as it's source of
energy.
Heat Exchanger - A component which 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 etc. and vice versa.
Heat Source - The area or media from which heat is removed. (water, air,
etc.)
Heat sink - The area or media where heat is deposited. (Inside a home,
etc.)
HAB - Heating mode: heat absorption capacity from the ground or water -
Cooling mode: heat absorption capacity from the inside air (total cooling load)
IGPM - Water flow in Imperial Gallons
KWH - Kilowatt hours - Electrical term - 1 Kwh equals the use of 1000 watts
for one hour.
KW OUT - Heat pump capacity in KW's
Liquid-to-Air Heat Pump - A heat pump which absorbs heat from a liquid and
distributes the energy in the form of hot forced air.
Liquid-to-Liquid heat pump - A heat pump which absorbs heat from a liquid and
distributes the energy in the form of hot water.
LWT - Leaving water temperature.
LAT - Leaving air temperature.
LLT - Leaving liquid temperature.
Latent - The load created by moisture in the air, including from outside air
infiltration and that from indoor sources such as occupants, plants, cooking,
showering, etc.
Mechanical Cooling - Conventional cooling provided by a compressor operated
refrigeration device. Term can be interchanged with "active cooling".
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.
Output - Heat pump capacity in Btu's/Ton's.
Passive Cooling - A process whereby cold well water (less than 50 degrees 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 which has all components (compressor, blower
and heat exchangers etc.) in one cabinet.
Refrigerant - 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 vise versa in response to the influence of a refrigeration compressor.
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
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.
Seasonal Coefficient of Performance (SCOP) - Is the average COP over the
entire heating season.
Seasonal Energy Efficiency Ratio (SEER) -The average cooling efficiency over
an entire cooling season.
Simple Payback 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.
Sensible - The interior heat gain due to heat conduction, convection, and
radiation from the exterior into the interior, and from occupants and
appliances.
TX Valve - A temperature and pressure controlled device for metering
refrigerant in a heat pump or other refrigeration device.
Ton (of refrigeration) - The amount of energy it takes to convert 2000 lbs. of
water at 32 degrees F. to ice at 32 degrees 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.
Turbotec - Trade name for a high efficiency expanded surface style coaxial
tube-in-tube heat exchanger.
Temp. diff. - Difference between ELT and a LLT.
Water Well - A vertical bore hole into the earths 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.
Water-to-Water - 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. ex.
extracting heat from a 50 degrees F. well and using it to heat domestic hot water at
120 degrees F
Geothermal Heating & Cooling Terminology
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