Glossary

A-Coil
A heat exchanger containing two diagonal coils that are connected together in a manner that resembles the letter "A".

AC
Abbreviation for alternating current, an electric current that reverses its direction many times a second.

AC or DC
Abbreviation for equipment capable of operating on alternating or direct current.

ACCA
Air Conditioning Contractors of America.

Acoustical
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. The unit is more efficient when the rating is higher.

AGA
Abbreviation for American Gas Association, Inc.

Air Cleaner
A piece of machinery that removes unwanted particles from moving air.

Air Conditioner
A system for controlling the humidity, ventilation, and temperature in a building or vehicle.

Air flow Volume
The amount of air the system circulates through your home, indicated in cubic feet per minute (cfm). Correct airflow depends on the indoor unit, the ductwork, the outdoor unit, and even whether the filters are clean.

Air handler
The portion of the central air conditioning or heat pump system that moves cooled or heated air throughout a home's ductwork. In some systems a furnace will handle this function.

ARI
Air Conditioning & Refrigeration Institute.

ASHRAE
American Society of Heating, Refrigeration and Air Conditioning Engineer

BTU
British thermal unit. The standard of measurement used to guage the amount of heat required to raise the temperature of one pound of water by one degree (Fahrenheit).

BTUh
British thermal units per hour. 12,000 BTUh equals one ton of cooling.

Burner
A instrument that uses fuel to support combustion.

Burner (sealed combustion)
A burner that acquires all air for combustion from outside the heated space.

Capacity
The ability of a heating or cooling system to cool or heat a given amount of space. For heating, this is usually expressed in BTU's. For cooling, it is often given in tons.

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
The abbreviation for cubic feet per minute, commonly used to measure the rate of air flow in an air conditioning system.

Charge
Adding refrigerant to a system. Refrigerant is 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. Still to this day, it's the only compressor Trane uses in its residential systems. The Trane Climatuff® Compressor is well known for its superior durability, high efficiency and low noise levels.

ComfortR™ 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.

ComfortR™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.

Compressor
The pump that moves the refrigerant from the indoor evaporator to the outdoor condenser and back to the evaporator again. The compressor is often called "the heart of the system" because it circulates the refrigerant through the loop.

Condensate
Vapor that liquefies due to the lowering of its temperature to the saturation point.

Condenser coil (or outdoor coil)
A series or network of tubes filled with refrigerant, normally located outside the home, that removes heat from the hot, gaseous refrigerant so that the refrigerant becomes liquid again.

Condenser Fan
The fan that distributes air over the aircooled condenser.

Contactor
A switch that can repeatedly cycle, making and breaking an electrical circuit. When ample current flows through the A-coil which is 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 keep the crankcase oil at a temperature higher than the coldest part of the system to prevent migration. Many newer cooling systems do not require crankcase heaters, however heat pumps do require crankcase heaters. Crankcase heaters are used to overcome the problem of migration and condensation of refrigerant in the crankcases of compressors used in air conditioning and heat pump systems.

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.

DC
Direct current electricity. This type of electricity (as opposed to Alternating Current, or AC) flows in one direction only, without reversing polarity.

Defrost
The process of removing ice or frost buildup from the outdoor coil during the heating season.

Degreeday
A computation that measures the amount of heating or cooling needed for a building. A degreeday is equal to 65 degrees Fahrenheit minus the mean outdoor temperature.

Dehumidifier
An air cooler that removes moisture from the air. This unit reduces water vapor in air by cooling the air below the dew point; removing water vapor from the air by chemical means, refrigeration, etc.

Diffuser
A grille over an air supply duct having vanes to distribute the discharging air in a defined pattern or direction.

DOE
Department of Energy

Downflow Furnace
A furnace that pulls in return air from the top and discharges warm air at the bottom.

Drain Pan
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 device that measures air temperature independently of humidity.

Ductwork
A pipe or conduit through which air is supplied. 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 principal as the equipment.

DX
Direct expansion. A system in which heat is passed on by the direct expansion of refrigerant.

EER
Energy Efficiency Ratio (steady state). Means the ratio of the cooling capacity of the air conditioner in British Thermal Units per hour, to the total electrical input in watts under ARI-specified test conditions.

ENERGY STAR®
Trane high efficiency systems carry the ENERGY STAR label which is the result of Trane's partnership with the U.S. Department of Energy and Environmental Protection Agency (EPA). ENERGY STAR products are more energy efficient and help reduce our whole earth's pollution issues. 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. ENERGY STAR is a joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy helping us all save money and protect the environment through energy efficient products and practices.

Evaporator Coil (or Indoor Coil)
The other half of an air conditioning system, this network of tubes filled with refrigerant which is located inside the home within the indoor unit, take heat and moisture out of indoor air as liquid refrigerant evaporates.

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). This is the most commonly used scale of temperature measurement in the United States of America.

Fan
Any device that creates air currents.

Filter
Any device used to remove dust and other impurities from air for the purposes of reducing the load on the respiratory system and to protect the HVAC equipment through a straining process. Filters vary greatly in particle arrestant; the higher the MERV rating (Minimum Efficiency Reporting Value- a number from 1 to 16 that is relative to an air filter’s efficiency), the better the filter.

Flue
Any vent or duct, pipe, or chimney for carrying exhaust gases from a fireplace, furnace, water heater, boiler, or generator to the outdoors.

Furnace
That part of an environmental system which converts gas, oil, electricity or other fuel into heat for distribution within a structure.

Fuse
A fuse is a type of overcurrent protection device. Its essential component is a metal wire or strip that melts when too much current flows, which breaks the circuit in which it is connected, thus protecting the circuit's other components from damage due to excessive current.

GAMA
Gas Appliance Manufacturers Association.

Gas Furnace Heat Exchanger
Found in the furnace, the heat exchanger transfers heat to the surrounding air, which is then transported throughout your home.

Heat Exchanger
An area, box or coil where heat flows from the warmer to the colder fluid or surface.
A device for the transfer of heat energy from the source to the conveying medium.