A
AC Abbreviation for alternating current, a type
of electric current in which the polarity is constantly reversing
causing the electron flow to reverse.
ACCA Air Conditioning Contractors of America
Acoustical Of or pertaining to sound.
AC or DC Abbreviation for equipment capable of
operating on alternating or direct current.
A-Coil A heat exchanger consisting of two
diagonal coils that are joined together in a manner that looks like
the letter "A".
AFUE Annual Fuel Utilization Efficiency. A
measure of a gas furnace's efficiency in converting fuel to energy -
the higher the rating, the more efficient the unit.
AGA Abbreviation for American Gas Association,
Inc.
Air Conditioner Any device that can change the
temperature, humidity or general quality of the air.
Air cleaner Any device that removes undesirable
particles from moving air.
Air flow volume The amount of air the system
circulates through your home, expressed in cubic feet per minute (cfm).
Proper air flow depends on the outdoor unit, the indoor unit, the
ductwork and even whether the filters are clean.
Air handler An air moving and/or mixing unit.
Residential air handlers include a blower, a coil, an expansion
device, a heater rack and filter. Heaters for air handlers are sold
as accessories. In some models heaters are factory installed.
ARI Air Conditioning & Refrigeration Institute
ASHRAE American Society of Heating,
Refrigeration and Air Conditioning Engineers
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B
BTU British thermal unit; the amount of heat
required to raise or lower the temperature of one pound of water one
degree Fahrenheit. The heat extracted from your home by an air
conditioner is measured in BTUs.
BTUh British thermal units per hour. 12,000 BTUh
equals one ton of cooling.
Burner A device that uses fuel to support
combustion.
Burner orifice The opening through which gas
flows to the air/gas mixing chamber of the burner.
Burner (sealed combustion) A burner that obtains
all air for combustion from outside the heated space.
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C
Capacity The output or producing ability of cooling or heating
systems. Cooling and heating capacities are referred to in British
thermal units (BTUs) per hour.
Celsius The metric temperature scale in which
water freezes at zero degrees and boils at 100 degrees, designated
by the symbol "C". To convert to Fahrenheit, multiply a Celsius
temperature by 9, divide by 5 and add 32 (25 x 9 equals 225, divided
by 5 equals 45, plus 32 equals 77 degrees Fahrenheit).
CFM Abbreviation for cubic feet per minute, a
standard measurement of airflow. A typical system requires 400 cfm
per ton of air conditioning.
Charge To add refrigerant to a system. This is
refrigerant contained in a sealed system or in the sensing bulb to a
thermostatic expansion valve.
Climatuff® Compressor The Trane Climatuff®
Compressor was the world's first successful heat pump compressor. To
this day it's the only compressor Trane uses in its residential
systems. It's well known for its superior durability, its low noise
levels, and high efficiency.
Comfort-R ™ Coil or Evaporator Coil A Trane
Comfort Coil is the other, less visible half of your air
conditioning system, and is located inside your home in the indoor
unit. It's a tubing coil in which a volatile liquid evaporates and
absorbs heat. This is where the refrigerant evaporates as it absorbs
heat from the indoor air that passes over the coil. It serves as a
"heat exchanger," moving heat into your home in the winter and away
from your home in the summer.
Comfort-R ™ Airflow System An exclusive feature
of a high efficiency home comfort system from Trane. This method of
ramping airflow gives you greater humidity control when cooling and
provides warmer air during heating start up.
Compressor This is the heart of an air
conditioning or heat pump system. It is part of the outdoor unit and
pumps refrigerant in order to meet the cooling requirements of the
system.
Condensate Vapor that liquefies due to the
lowering of its temperature to the saturation point.
Condenser coil (or outdoor coil) In an air
conditioner, the coil dissipates heat from the refrigerant, changing
the refrigerant from vapor to liquid. In a heat pump system, the
coil absorbs heat from the outdoors.
Condenser fan The fan that circulates air over
the air-cooled condenser.
Contactor A switch that can repeatedly cycle,
making and breaking an electrical circuit. When sufficient current
flows through the A-coil built into the contactor, the resulting
magnetic field causes the contacts to be pulled in or closed.
Crankcase heater This is the electric resistance
heater installed on compressor crankcases to boil off liquid
refrigerant that may have combined with compressor oil. Many newer
cooling systems do not require crankcase heaters, however heat pumps
do require crankcase heaters.
CSA Canadian Standards Association.
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D
DC Direct current electricity. This type of
electricity (as opposed to Alternating Current, or AC) flows in one
direction only, without reversing polarity.
Damper Found in ductwork, this movable plate
opens and closes to control airflow.
Dampers can be used to balance airflow in a duct
system. They are also used in zoning to regulate airflow to certain
rooms.
Defrost To melt frost; as in from an air
conditioner or heat pump coil.
Degree-day A degree-day is a computation that
gauges the amount of heating or cooling needed for a building. A
degree-day is equal to 65 degrees Fahrenheit minus the mean outdoor
temperature.
Dehumidifier An air cooler that removes moisture
from the air.
Diffuser A grille over an air supply duct having
vanes to distribute the discharging air in a specific pattern or
direction.
DOE Department of Energy
Downflow furnace A furnace that intakes air at
its top and discharges air at its bottom.
Drain pan This also referred to as a condensate
pan. This is a pan used to catch and collect condensate (in
residential systems vapor is liquefied on the indoor coil, collected
in the drain pan and removed through a drain line).
Dry bulb temperature Heat intensity, measured by
a dry bulb thermometer.
Dry bulb thermometer An instrument that measures
air temperature independently of humidity.
Ductwork A pipe or conduit through which air is
delivered. Ducts are typically made of metal, fiberboard or a
flexible material. In a home comfort system, the size and
application of ductwork is critical to performance and is as
important as the equipment.
DX Direct expansion; a system in which heat is
transferred by the direct expansion of refrigerant.
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E
EER Energy Efficiency Ratio (steady state)
ENERGY STAR® Trane high efficiency systems carry
the ENERGY STAR label. The result of Trane's partnership with the
U.S. Department of Energy, Environmental Protection Agency (EPA),
ENERGY STAR products are more energy efficient and help reduce our
whole earth's pollution problems. Choosing a Trane ENERGY STAR
Comfort System assures homeowners of lower energy bills and improved
indoor air quality for their home.
EPA Environmental Protection Agency
Expansion Valve A refrigerant-metering valve
with a pressure or temperature controlled orifice.
Evaporator coil (or indoor coil) The other half
of your air conditioning system located inside your home in the
indoor unit. This is a tubing coil in which a volatile liquid
evaporates and absorbs heat. This is where the refrigerant
evaporates as it absorbs heat from the indoor air that passes over
the coil.
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F
Fahrenheit The temperature scale on which water
freezes at 32 degrees and boils at 212 degrees; designated by the
letter F. To convert Fahrenheit to Celsius, subtract 32 from the
Fahrenheit number, multiply by 5 and divide by 9 (77 -32 equals 45,
times 5 equals 225, divided by 9 equals 25 degrees Celsius).
Fan Any device that creates air currents.
Filter Any device that removes impurities
through a straining process.
Flue Any vent or passageway that carries the
products of combustion from a furnace.
Furnace That part of the heating system in which
the combustion of fossil fuel and transfer of heat occurs.
Fuse A metal strip in an electrical circuit that
melts and breaks the circuit when excessive current flows through
it. The fuse is designed to break in order to save more expensive
electrical components.
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G
GAMA Gas Appliance Manufacturers Association
Gas Furnace Heat Exchanger Located in the
furnace, the heat exchanger transfers heat to the surrounding air,
which is then pumped throughout your home.
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H
Heat Exchanger An area, box or coil where heat
flows from the warmer to the colder fluid or surface.
Heat Gain Heat added to the conditioned space by
infiltration, solar radiation, occupant respiration and lighting.
Heating Coil Any coil that serves as a heat
source.
Heat Loss The rate of heat transfer from a
heated space to the outdoors.
Heat Pump A mechanical-compression cycle
refrigeration system that can be reversed to either heat or cool the
controlled space.
Heat Transfer The movement of heat energy from
one point to another. The means for such movement are conduction,
convection, and radiation.
Hertz In alternating current (AC electricity),
the number of cycles per second.
HSPF Heating Seasonal Performance Factor. This
rating is used in measuring the heating efficiency of a heat pump.
The higher the number the more efficient the heat pump system.
Humidifier A machine that adds water vapor to the air to increase
humidity.
Humidistat A humidity-sensing control that
cycles the humidifier on and off.
Humidity The presence of water vapor in the air.
Humidity, absolute Weight of water vapor per
cubic foot of dry air, expressed as grains of moisture per cubic
foot.
Humidity, relative The amount of moisture in the
air expressed as a percentage of the maximum amount that the air is
capable of holding at a specific temperature.
HVAC Abbreviation for Heating, Ventilating and
Air Conditioning
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I
Ignition The lighting of a fuel to make it burn.
K
Kilowatt (kW) 1,000 watts.
L
Latent Heat A type of heat, which when added to
or taken from a substance, does not change the temperature of the
substance. Instead, the heat energy enables the substance to change
its state.
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M
Media The material in a filter that traps and
holds the impurities.
N
NEC National Energy Council / National Electric
Code
NEMA National Electrical Manufacturing
Association
O
OEM Original equipment manufacturer.
Orifice An opening or hole; an inlet or outlet.
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P
Package Unit A heating and cooling system
contained in one outdoor unit. A package unit is typically installed
beside, on the roof, or sometimes in the attic of a home.
PSI Pounds per square inch.
PSIA Pounds per square inch, absolute.
PSIG Pounds per square inch gauge.
PVC Polyvinyl chloride; a type of plastic.
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R
Reciprocating Compressor A compressor whose
piston or pistons move back and forth in the cylinders.
Refrigerant A chemical that produces a
refrigerating effect while expanding and vaporizing. Most
residential air conditioning systems contain R-22 refrigerant. R-22
is regulated under the Montreal Protocol and in the United States by
the Environmental Protection Agency. R-22 is scheduled to be in
production until the year 2020. It's used in approximately 95
percent of air conditioning equipment manufactured in the U.S.
today.
Refrigerant Charge The required amount of
refrigerant in a system.
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S
SEER Seasonal Energy Efficiency Ratio; a measure
of cooling efficiency for air conditioners and heat pumps. The
higher the SEER, the more energy efficient the unit.
Self-contained System A refrigerating system
that can be moved without disconnecting any refrigerant lines; also
know as a package unit.
Sensible Heat That heat which, when added to or
taken away from a substance, causes a rise or fall in temperature.
Sensor Any device that reacts to a change in the
conditions being measured, permitting the condition to be
controlled.
Setpoint The temperature or pressure at which a
controller is set with the expectation that this will be a nominal
value depending on the range of the controller.
Spine Fin™ Coil All-aluminum outdoor coil that
features the patented Spine Fin™ design. It provides greater heat
exchanging capabilities (meaning higher efficiencies) and is more
resistant to corrosion than traditional copper/aluminum
Split System The combination of an outdoor unit
(air conditioner or heat pump) with an indoor unit (furnace or air
handler). Split systems must be matched for optimum efficiency.
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T
Thermostatic Expansion Valve A refrigerant
metering device that maintains a constant evaporator temperature by
monitoring suction vapor superheat; also called a thermal expansion
valve.
Thermostat A thermostat consists of a series of
sensors and relays that monitor and control the functions of a
heating and cooling system.
Ton A unit of measurement used for determining
cooling capacity. One ton is the equivalent of 12,000 BTUs per hour.
Two-stage heating / Two-stage cooling Two-stage
heating and cooling is considered to be more efficient, because it
operates at low speed most of the time. However, on days when more
heating or air conditioning is required, it switches to the next
stage for maximum comfort.
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U
U-Factor The factor representing resistance to
heat flow of various building materials.
UL Underwriters Laboratories
Upflow Furnace A furnace in which air is drawn
in through the sides or bottom and discharged out the top.
V
Vacuum A pressure below atmospheric pressure. A
perfect vacuum is 30 inches Mercury (periodic symbol "Hg").
Variable-speed motor(s) The fan motor inside
Trane's variable-speed air handlers is designed to vary its speed
based on your home's heating and air conditioning requirements.
Working in conjunction with your thermostat, it keeps the
appropriate-temperature air (e.g. warm air on cold days) circulating
throughout your home, reducing temperature variances in your home.
It also provides greater air circulation and filtration, better
temperature distribution, humidity control, higher efficiency, and
quiet performance.
Volt The unit of measure used to describe a
difference in electrical potential; abbreviated by the symbol "v".
Voltage The force that pushes electrical current
along wires and cables.
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W
Watt The unit of electrical power equal to the
flow of one amp at a potential difference of one volt.
Wet Bulb Thermometer A thermometer whose bulb is
covered with a piece of water-soaked cloth. The lowering of
temperature that results from the evaporation of water around the
bulb indicates the air's relative humidity.
Z
Zoning System A method of dividing a home into
different comfort zones so each zone can be independently controlled
depending on use and need; an air conditioning system capable of
maintaining varying conditions for various rooms or zones.
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