Air Conditioner - A system designed to control aspects of indoor comfort such as air quality, temperature, humidity and flow.

Air Handler - A piece of equipment dedicated to moving conditioned air through a home. Air handler most commonly refers to the indoor portion of an electric auxiliary heater, and all necessary controls required to operate it.

Blower - A component of an air handler or furnace composed of a motor, wheel, and housing that is responsible for forcing air in the HVAC system.

Charge - The quantity of refrigerant necessary to operated an HVAC system.

Coil - A component of an HVAC system responsible for heat transfer via refrigerant as well as its role in change of refrigerant state (gas to liquid and vice versa)

Compressor - A component in an HVAC system responsible for compressing refrigerant and circulating it.

Condenser Coil - A piece of equipment in an HVAC system responsible for condensing refrigerant by exhausting absorbed heat (usually by means of forced air over the coils surface.)

Duct - An individual pipe (usually compsed of round or rectangular sheet metal, fiberboard, or insulated flexible pipe) responsible for directing conditioned air to a given area in the home.

Ductless Mini‐Split - An air conditioning or heat pump system that does not utilize ducts to move air. Due to the fact that ducts are not used, ductless air handlers must be installed in each room to be conditioned and connected to an individual heat pump or a multi-point inverted heat pump.

Duel Fuel System- An HVAC system engineered to provide a home with two separate sources of heat as an alternative to single fuel heat. Can be offered in certain climates as an economical option for heating. In periods of low demand for heating, a heat pump functions as the heat source. In periods of high demand and/or low ambient temperatures, the system uses gas combustion as the heat source.

EER (Energy Efficiency Ratio) - Numeric value determined by a ratio indicating the efficiency of an air conditioner. A higher value dictates a more efficient unit. EER ratings are typically lower than SEER ratings due to their being calculated by a fixed ambient temperature.

Evaporator Coil - A series of tubes running through a block of aluminum fins (to increase area for more efficient heat transfer) that contain liquid refrigerant, which absorbs heat from air causing the refrigerant to boil and evaporate.

Fresh Air Intake - An opening to pull fresh air into a system.

Furnace - A piece of equipment that heats air by gas combustion through a heat exchanger.

Heat Pump - A piece of equipment similar to a condenser except that it utilizes a reversing valve to reverse the flow of refrigerant providing both heating and cooling.

HSPF - An abbreviation for Heating Seasonal Performance Factor. This number represents the efficiency of a heat pump during heating operation. A higher HSPF indicates higher efficiency.

HVAC - An abbreviation which stands for Heating, Ventilation, and Air Conditioning.

Humidity - The amount of moisture measured in the air.

Load Calculation - A calculation to determine heat load and loss of a home through building materials and insulation used to engineer a properly sized HVAC system.

R‐22 - An hydrochlorofluorocarbon (HCFC) refrigerant, commonly referred to as Freon. The EPA is phasing out its use and production doe to its chlorine content, which depletes ozone.

R‐410A - A hydroflourocarbon refrigerant commonly referred to as Puron. It is the new standard refrigerant used in residential HVAC systems due to the absence of ozone depleting chlorine in the compound.

Refrigerant - A chemical used in HVAC designed to facilitate heat absorption and transfer via an evaporator, refrigerant lines and a condenser.

Register - A louvered grille covering the opening of a boot at the end of an air duct. Supply registers are typically dampered while return registers are not.

Relative Humidity - Stated as a percentage, relative humidity is the actual amount of moisture in the air versus the maximum amount of moisture air could hold at the same temperature.

Return Air - The air taken into a system to be conditioned and circulated.

SEER - Abbreviation for Seasonal Energy Efficiency Ratio. SEER indicates the efficiency during an average cooling season and is calculated by using both the hottest and coolest days of the season. A higher SEER rating indicates a more efficient unit.

Split System - Most common type of residential system. Composed of an air handler or furnace and an evaporator indoors as well as a condenser outdoors.

System - A term referring to all components required to condition the air in a home.

Tonnage - Measure of capacity of cooling for a system. One ton refers to the amount of heat necessary to melt one ton of ice in 24 hours.

Zoning - Zoning - A system used for isolating and conditioning individual areas using a single HVAC system. Consists of individual dampers and controls for each area, or "zone".