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. For example: A rating of 90 means that approximately 90 percent of the fuel is used to provide warmth to your home, while the remaining 10 percent escapes as exhaust.
BTU
British Thermal Unit. This is the amount of heat it takes to raise one pound of water one degree Fahrenheit. For your home, it represents the measure of heat given off when fuel is burned for heating or the measure of heat extracted from your home for cooling.
CFM
Cubic Feet Per Minute. A standard measurement of airflow. A typical system requires 400 CFM per ton of air conditioning.
Capacity
The output or producing ability of a piece of cooling or heating equipment. Cooling and heating capacities are referred to as BTUs.
Coil
In air conditioning, a network of tubes filled with refrigerant. A coil located inside the home takes heat and moisture out of the air as liquid refrigerant evaporates. Sometimes called a evaporator or cooling coil. See also Condenser.
Compressor
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.
Condenser
That part of a refrigeration system which pumps vaporized refrigerant from the evaporator inside your home, compresses it, liquefies it in the condenser and returns the liquid refrigerant to refrigerant control to remove heat from your home. The compressor is located here.
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.
Ductwork
Pipes or channels that carry air throughout your home. In a home comfort system, ductwork is critical to performance - in fact, it’s as critical as the equipment.
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
Device used to transfer heat from a warm or hot surface to a cold or cooler surface. Evaporators and condensers are heat exchangers.
Hot Surface Ignition System
Furnace ignition system in which a silicon carbide element is heated in order to light the main burner. No pilot light is needed.
Packaged Unit
A heating and cooling system contained in one outdoor unit. A package unit is typically installed either beside, on top of the home, or sometimes in the attic.
Refrigerant
A chemical that produces a refrigerating effect - removing heat and humidity from the air - while expanding and vaporizing. Most residential air conditioning systems contain R-22 refrigerant. R-22 is regulated by international controls under the Montreal Protocol and in the United States by the Environmental Protection Agency. It 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.
SEER
Seasonal Energy Efficiency Ratio. A measure of cooling efficiency for air conditioners and heat pumps. (It’s similar to comparing miles per gallon in automobiles.) It is a ratio which compares the cooling output to the electric consumption over a range of temperatures. The higher the seer, the more energy efficient the unit. The government’s minimum SEER rating is 13 as of 2006.
Thermocouple
A device that generates electricity, using the principle that when two dissimilar metals are joined together and the junction is heated, a low voltage will develop across the ends.
Thermostat
A thermostat consists of a series of sensors and relays that monitor and control the functions of a heating and cooling system.
Ton of Refrigeration
Refrigerating effect equal to melting one ton of ice in 24 hours. This may be expressed as follows: 288,000 BTU/24-hours, 12,000 BTU/hour or 200 BTU/minute.
Zoning
A method of dividing a home into different comfort zones so each zone can be independently controlled depending on use and need.
