BTU
British Thermal Units. 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.

Capacity
The ability of a heating or cooling system to heat or cool a given amount of space. Heating is usually expressed in BTUs, cooling is expressed in tons.

Compressor
The motor/pump that drives the air conditioning unit. It is responsible for pumping refrigerant throughout the system.

Condenser Coil
Part of the outdoor portion of a heating or cooling system, that releases or collects heat from the outside air.

Damper
A valve or moveable plate used in duct work that opens and closes to control airflow. They are used to direct air to specific areas of the home.

Downflow
A type of furnace that takes cool air from the top and blows warm air to the bottom.

Ductwork
Hollow metal pipes used to transfer air throughout your house.

Electronic Air Cleaner
An electronic device that filters out particles and contaminants in indoor air.

Evaporator Coil
Part of the heating or cooling system located indoors, that cools and dehumidifies the air by converting liquid refrigerant into gas.

Heat Exchanger
The major part of the furnace that transfers heat into your home.

Heat Pump
A unit that handles both heating and cooling. In some climates, a heat pump may handle your heating and cooling needs more efficiently than a furnace and air conditioner.

Horizontal Flow
A type of furnace, installed on its side, which draws air from one side, heats the air and then sends it our the other side.

HSPF
Heating Seasonal Performance Factor. Measures the heating efficiency of a heat pump. The higher the number the more efficient the heat pump heats your home.

Humidifier
A piece of equipment that adds moisture to the air as it comes out of the furnace.

HVAC
Heating, Ventilation and Air Conditioning

Refrigerant
A chemical that cools air as it evaporates.

SEER
Seasonal Energy Efficiency Rating. SEER measures a unit's cooling efficiency. The higher the number, the greater the efficiency.

Single Package
An outdoor unit that contains both a heating and a cooling system.

Split System
Refers to an air conditioner or heat pump that is combined with indoor components, such as an evaporator coil inside and a condenser coil outside your home.

Thermostat
A device that monitors and controls your temperature inside your home.

Upflow
A type of furnace that draws cool air from the bottom and blows the warmed air out the top.

Ventilator
A ventilator captures heating or cooling energy from stale indoor air and transfers it to fresh incoming air.

Zone
Zoning allows you to control the heating and cooling delivered to specific areas of your house for a custom solution. Zoning can increase efficiency and comfort in the areas of the house you use most often.