AFUE
Stands for Annual Fuel Utilization Efficiency. This number represents how efficiently a furnace converts fuel to energy. The higher the rating, the more fuel-efficient the furnace is. Percentage of fuel used for heating.

Air Handler
The portion of your air conditioner or heating system that forces air through your home's ductwork.

BTU
Stands for British Thermal Units. This number indicates the amount of heat it takes to raise one pound of water one degree Fahrenheit. The higher the BTU rating, the larger the heating capacity of the furnace or air conditioner. Homes are measured to determine the number of BTUs required from a heating or cooling system.

Capacity
Heating and cooling equipment capacities are measured in BTUs. The amount of heat the air conditioning unit can remove.

Carbon Monoxide
A colorless, odorless, highly poisonous gas produced when carbon burns without sufficient air nearby.

CFM
Stands for Cubic Feet per Minute. A measurement of airflow that indicates how many cubic feet of air pass by a stationary point in one minute. The higher the number, the more air is being forced through the system.

Combustion Air
The air fed to a fire to provide oxygen for combustion of fuel. It may be preheated before injection into a furnace. Combustion efficiency: actual heat produced by combustion total heat potential of the fuel consumed .

Compressor
The Compressor is the most important piece of a heating or cooling system. Located in the outdoor unit, the compressor is responsible for pumping refrigerant throughout the system.

Condenser Coil
The outdoor portion of a heating or cooling system that either releases or collects heat from the outside air, depending on the time of year. The Condenser Coil is connected directly to the home's Air Handler and is also known as the Outdoor Coil.

Damper
A movable plate that controls airflow through a ductwork system. Dampers are used to direct air to the areas of the home that need it most.

Evaporator Coil
This is where refrigerant evaporates as it removes heat from the air that is passed over it. The Evaporator Coil is located in the indoor unit and is also referred to as the Indoor Coil.

Heat Exchanger
The part of a furnace that transers heat to nearby air. That air is then distributed through the Ductwork throughout your home.

Heat Pump
A heating and air conditioning unit that heats or cools by moving heat.

HSPF
Stands for Heating Seasonal Performance Factor. Indicates how efficiently a Heat Pump is working. A higher number means the unit works more efficiently. Most new units have ratings from 7.0 to 9.4.

Humidifier
A component that adds moisture to the air before it is distributed by the Ductwork throughout the house.

HVAC
Stands for Heating, Ventilation and Air Conditioning.

Indoor Coil
See: Evaporator Coil

Outdoor Coil
See: Condenser Coil

Refrigerant
A chemical that cools air as it evaporates. Air conditioning systems use Refrigerant in the Evaporator Coil to cool air as it passes by.

Refrigerant Lines
Two copper lines that connect the Condenser (Outdoor) Coil to the Evaporator (Indoor) Coil.

SEER
Stands for Seasonal Energy Efficiency Ratio. An efficiency measurement that is similar to Miles Per Gallon for cars. The higher this number, the more energy efficient the system is. New units have SEER ratings from 10 to 17 BTUS per watt.

Single Package
One outdoor unit that contrains both a heating and a cooling system.

Split System
A combination heat pump or air conditioner with indoor components such as a furnace or blower coil. To maximize effectiveness, Split Systems should be matched.

Thermostat
A device that allows you to control the temperature inside your home by telling the heating or cooling system how much air to produce.

Zoning
The dividing of a home into different areas, each with their own heating and cooling properties. For example, you might prefer to have the kitchen area of your home be slightly cooler, while at the same time keeping the temperature in the bedrooms warmer.