AFUE
Annualized Fuel Utilization Efficiency is a measure of your furnaces' heating efficiency. The higher the AFUE percentage, the more efficiency the furnace.
Air Handler/ Coil Blower
The indoor part of an air conditioner or heat pump that moves cooled or heated air throughout the ductwork of your home. An air handler is usually a furnace or a blower coil.
Btu
A British thermal unit of heat energy. One Btu is the amount of heat required to raise on pound of water by one degree Fahrenheit. The higher the Btu rating, the greater the heating capacity of the system.
Btuh
British thermal units per hour.
CFM
Stands for Cubin Feet per Minute. This measurement 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 ductwork by the system.