A-Coil
A heat exchanger (evaporator coil) consisting of two diagonal coils that are joined together in a manner that looks like the letter “A”.
AC
Abbreviation for alternating current, a type of electric current in which the polarity is constantly reversing, causing the electron flow to reverse
AC or DC
Abbreviation for equipment capable of operating on alternating or direct current.
ACCA
Air-Conditioning Contractors of America.
Accoustical
Of or pertaining to sound.
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.
AHRI
Air Conditioning, Heating & Refrigeration Institute
Air cleaner (also Air Filtration System)
Removes airborne allergens from your home.
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 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. The portion of your heating and cooling system that forces air through your home’s ductwork.
ASHRAE
American Society of Heating, Refrigeration and Air Conditioning Engineers- ASHRAE is an international voluntary organization for people involved in heating, ventilation, air conditioning, or refrigeration (HVAC&R).

The society promotes the general sciences of HVAC&R. The main Society headquarters is located in Atlanta, Georgia with local chapters located across the United States and throughout the world.

ASHRAE publishes a four-volume Handbook that serves as a resource for members, with one of the four volumes updated each year. ASHRAE also publishes a well recognized series of standards and guidelines relating to HVAC Systems. ASHRAE Standards are often referenced in other model building codes and in the US Green Building Council’s Leadership in Energy Design (LEED) green building rating system.

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 (sealed combustion)
A burner that obtains all air for combustion from outside the heated space.
Burner Orifice
The opening through which gas flows to the air/gas mixing chamber of the burner.
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).
Certified Matched System
The Air Conditioning, Heating and Refrigeration Institute (AHRI) puts heating and cooling equipment through rigorous certification processes to ensure systems deliver the promised performance at certain test conditions.
CFM
Abbreviation for cubic feet per minute, a standard measurement of airflow. A typical system requires 400 cfm of air flow 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)
Part of the outdoor portion of a heating or cooling system, which releases or collects heat from the outside air.
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.
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.
Ecologic
Maytag’s_ designation of green heating and cooling equipment.
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
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.
Expansion valve
A refrigerant-metering valve with a pressure- or temperature-controlled orifice.
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.
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.
Heat exchanger
An area, box or coil where heat flows from the warmer to the colder fluid or surface. The major part of the furnace that transfers heat into your home.
Heat gain
Heat added to the conditioned space by infiltration, solar radiation, occupant respiration and lighting.
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.
Heating coil
Any coil that serves as a heat source.
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 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.
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.
Inverter Compressor
The air conditioner and heat pump utilize inverter technology compressors to convert the electrical current from
AC to DC. In doing so, the systems almost infinitely vary the compressor and fan speed motors. The air
conditioner and heat pump can modulate anywhere from 40% to 100% of capacity, instantly adjusting to exactly
offset the demands on the home. Because these units do not cycle on and off like a traditional system, they save
a considerable amount of energy and reduce noise levels.
Kilowatt (kW)
1,000 watts
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.
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.
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
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.
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.
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.
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.
Thermostat
A thermostat consists of a series of sensors and relays that monitor and control the functions of a heating and
cooling system.
Thermostatic expansion valve
A refrigerant metering device that maintains a constant evaporator temperature by monitoring suction vapor
superheat; also called a thermal expansion valve.
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.
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.
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.
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.
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.