GLOSSARY

Be knowledgeable about HVAC. Here are definitions of terms that can help you understand your system better.

A

    B

      C

        D

          E

            F

              G

                H

                  I

                    J

                      K

                        L

                          M

                            N

                              O

                                P

                                  Q

                                    R

                                      S

                                        T

                                          U

                                            V

                                              W

                                                X

                                                  Y

                                                    Z

                                                    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.
                                                    Accoustical
                                                    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. More specifically, an air conditioner makes your home cooler,
                                                    by drawing heat energy out of the house and transferring that heat to
                                                    the outdoors.
                                                    Air cleaner (also Air Filtration System)
                                                    Removes airborne allergens from your home.
                                                    Air Filtration System (also Air Cleaner)
                                                    Removes airborne allergens from your home.
                                                    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 a filter.
                                                    Heaters for air handlers are sold as accessories. In some models,
                                                    heaters are factory installed.
                                                    AHRI
                                                    Conditioning, Heating & 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 Office
                                                    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

                                                    CADR Clean Air Delivery Rate (CADR)
                                                    provides
                                                    the number of cubic feet of clean air that a unit delivers each minute.
                                                    Efficiency of the system times the air flow of the system.
                                                    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.
                                                    CleanEffects™ (also Trane CleanEffects™)
                                                    Trane
                                                    Air filtration system that removes 99.98% of airborne allergens down to
                                                    .1 micron from the filtered air, making it 100 times more effective
                                                    than a standard 1″ filter. Trane CleanEffects also removes over 99% of
                                                    the influenza virus from your home’s filtered air, according to
                                                    research by the Harvard School of Public Health, in collaboration with
                                                    scientists at Environmental Health and Engineering Inc. (EH&E).
                                                    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™ coil (also evaporator coil or indoor coil)
                                                    Part
                                                    of an indoor air unit, it functions with the air conditioner or heat
                                                    pump outdoors to cool and condition indoor air that flows over it by
                                                    drawing out heat and moisture.
                                                    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

                                                    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.
                                                    DB (Decibels)
                                                    A unit to measure sound.
                                                    DC
                                                    Direct
                                                    current electricity. This type of electricity (as opposed to
                                                    Alternating Current, or AC) flows in one direction only, without
                                                    reversing polarity.
                                                    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
                                                    is 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.
                                                    Dual Compressors
                                                    An
                                                    outdoor unit featuring two compressors, one for everyday cooling and a
                                                    second larger one for extreme temperature days. Provides superior
                                                    durability designed for cost-saving efficiency and low sound levels.
                                                    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)
                                                    Electronic Air Cleaner (EAC)
                                                    Electronically filters out magnetized airborne particles from contaminants in indoor air, sending them to a collector plate.
                                                    Energy recovery ventilator (also FreshEffects™ or Trane FreshEffects™)
                                                    Energy efficient system to exchange stale indoor air for an equal amount of fresher outdoor air.
                                                    ENERGY STAR®
                                                    Trane’s
                                                    high efficiency systems carry the ENERGY STAR label. The result of
                                                    Trane’s partnership with the U.S. Department of Energy and the
                                                    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 (also Comfort™ Coil or Indoor coil)
                                                    Part
                                                    of an indoor air unit, it functions with the air conditioner or heat
                                                    pump outdoors to cool and condition indoor air that flows over it by
                                                    drawing out heat and moisture.

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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.
                                                    FreshEffects™ (also Energy Recovery Ventilator or Trane FreshEffects™)
                                                    Energy-efficient system to exchange stale indoor air for an equal amount of fresher outdoor air.
                                                    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.
                                                    HEPA filter
                                                    Filter that traps airborne particles by forcing air through very dense mesh.
                                                    Hertz
                                                    In alternating current (AC electricity), the number of cycles per second.
                                                    Horizontal flow
                                                    Often used in attics/crawl spaces, this furnace takes air from its side, heats it and sends warm air out the other side.
                                                    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.
                                                    Hybrid heat (also Hybrid System)
                                                    Provides energy-efficient comfort for moderate heating conditions. Can use either gas or electricity.
                                                    Hybrid system (also Hybrid Heat)
                                                    This
                                                    type of system provides energy-efficient comfort for moderate heating
                                                    conditions. Depending on the weather and your comfort needs, it can use
                                                    either gas or electricity, with an electric heat pump as the outdoor
                                                    component and a gas furnace the indoor component.

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                                                    I

                                                    Ignition
                                                    The lighting of a fuel to make it burn.
                                                    Indoor coil (also Comfort™ Coil or evaporator coil)
                                                    Part
                                                    of an indoor air unit, it functions with the air conditioner or heat
                                                    pump outdoors to cool and condition indoor air that flows over it by
                                                    drawing out heat and moisture.
                                                    Indoor/Outdoor system (also 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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                                                    J

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                                                    K

                                                    Kilowatt (kW)
                                                    1,000 watts

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                                                    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.
                                                    Load calculation
                                                    Assessed
                                                    by a dealer, the calculation factors in a number of criteria in your
                                                    home (square footage, number of windows, year-round weather concerns)
                                                    and determines what size components you should include as part of your
                                                    total comfort system.

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                                                    M

                                                    Matched system
                                                    System
                                                    includes multiple Trane components designed and engineered to work
                                                    seamlessly together to enhance overall performance, reliability and
                                                    efficiency.
                                                    Media
                                                    The material in a filter that traps and holds the impurities.

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                                                    N

                                                    NATE
                                                    North
                                                    American Technician Excellence—certification acknowledging a
                                                    dealer/technician as one of the most knowledgeable and experienced at
                                                    installing and servicing high-performance, precision-engineered heating
                                                    and cooling systems.
                                                    NEC
                                                    National Energy Council / National Electric Code
                                                    NEMA
                                                    National Electrical Manufacturing Association

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                                                    O

                                                    OEM
                                                    Original Equipment Manufacturer.
                                                    Operating cost
                                                    Cost of running your home comfort system, based on energy usage.
                                                    Orifice
                                                    An opening or hole; an inlet or outlet.
                                                    Outdoor coil (also Condenser coil)
                                                    In
                                                    a heat pump, it takes in heat to warm your home. In an air conditioner,
                                                    it dissipates heat from the refrigerant, changing the refrigerant from
                                                    vapor to liquid to cool your home.

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                                                    P

                                                    Packaged system (or Packaged unit)
                                                    A single cabinet, typically installed outside, that houses both heating and cooling components.
                                                    Packaged unit (or Packaged system)
                                                    A single cabinet, typically installed outside, that houses both
                                                    Payback analysis
                                                    Number of years required before your monthly energy savings offset the original HVAC investment.
                                                    PSI
                                                    Pounds per square inch.
                                                    PSIA
                                                    per square inch, absolute.
                                                    PSIG
                                                    Pounds per square inch gauge.
                                                    PVC
                                                    Polyvinyl chloride; a type of plastic.

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                                                    Q

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                                                    R

                                                    Reciprocating compressor
                                                    A compressor whose piston or pistons move back and forth in the cylinders.
                                                    Reclaiming
                                                    Returning used refrigerant to the manufacturer for disposal/reuse.
                                                    Recycling
                                                    Removing, cleaning and reusing refrigerant.
                                                    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.
                                                    Refrigerant charge
                                                    The required amount of refrigerant in a system.
                                                    Refrigerant lines
                                                    Two copper lines connecting the outdoor condenser to the indoor evaporator coil.

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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.
                                                    SEET
                                                    Seasonal
                                                    Extreme Environmental Test; Trane facility that simulates series of
                                                    rigorous tests to ensure the quality/reliability of outdoor units.
                                                    Self-contained system
                                                    A refrigerating system that can be moved without disconnecting any refrigerant lines; also known 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 a traditional copper/aluminum coil.
                                                    Split system (also indoor/outdoor 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.
                                                    Trane CleanEffects™ (also CleanEffects™)
                                                    Trane
                                                    air filtration system that removes up to 99.98% of airborne allergens
                                                    down to .1 micron from the filtered air, making it 100 times more
                                                    effective that a standard 1″ filter. Trane CleanEffects also removes
                                                    over 99% of the influenza virus from your home’s filtered air,
                                                    according to research by the Harvard School of Public Health, in
                                                    collaboration with scientists at Environmental Health and Engineering
                                                    Inc. (EH&E).
                                                    Trane FreshEffects™ (also Energy Recovery Ventilator or FreshEffects™)
                                                    Energy-efficient system to exchange stale indoor air for an equal amount of fresher outdoor air.
                                                    Two-stage compressor
                                                    Compressor composed of a high and low stage to increase efficiency and comfort while reducing operation noise.
                                                    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.

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                                                    V

                                                    Vacuum
                                                    A pressure below atmospheric pressure. A perfect vacuum is 30 inches of 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.

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                                                    X

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                                                    Y

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                                                    Z

                                                    Zoning
                                                    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.
                                                    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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