Condenser: Component of an air conditioning system located outside the structure, commonly called and air conditioner.
Heat Pump: An air conditioner equipped to reverse the flow of refrigerant in the winter to heat the home. Heat pumps are efficient because they are designed to move heat not create heat/burn fuel. Less energy is used to do this, thus saving energy and money.

Dual Fuel System: A heat pump paired with a regular gas furnace that operates automatically when it is too cold outside for the heat pump to be efficient (about 28 degrees Fahrenheit). This is the best of both worlds – comfort and efficiency.

Coil: Usually refers to the inside “evaporator” coil commonly used as a cooling component inside the house. Also used in a heat pump for transferring heat indoors.
Line Set: The copper lines that carry the refrigerant in and out of the house.

SEER: Seasonal Energy Efficiency Ratio. A measure of efficiency for air conditioners. Each higher SEER level is between 8-10% more efficient than a 10 SEER.