Glossary of Terms

Heating Venting and Air Conditioning(HVAC)


Air ConditionerHP-Left Quarter – Device used to lower air temperature. Cooling typically happens through heat transfer with refrigerant cycle.

Air Handler/Electric Furnace Daikin Air Handler – Metal box containing blower, heating elements and system controls. Normally attached to duct work which distributes conditioned air throughout a building.

BTU (British Thermal Unit) – Measurement of energy(heat) required to raise a temperature. In the U.S., BTU is used for the rating power of HVAC systems.

Coil daikin-coil-capf-rightquarter-withbadge-case-lr– Equipment that performs a heat transfer as air blows over the unit.

Damper damper-sleeve– An adjustable blade inside duct to control air flow.

Dehumidifier Extra Large TrueDRY Dehumidifier - 3 in. Color – Equipment used to extract and remove humidity from air. Drops air temperature to turn water vapor to liquid. Dehumidification naturally occurs during air conditioning.

Duct flex-duct– Method of transferring air from one area to another. Used in heating, cooling or ventilation.

Fresh Air – Outside air that is introduced inside a building to help cycle new air.

Filter  filter– Removable device that is placed in the air intake portion of the system. It provides protection for the motor, fan, and heating coil by removing impurities. It also contributes to the Indoor Air Quality of a building.

Furnace Daikin Gas Furnace – Similar to an air handler. Metal box containing burners, heat exchanger, blower and controls. Fuel can be Natural Gas, Propane, or Oil.

Grille  grille – A covering over a duct opening that has slots in it to deliver(supply) or recover(return) air. The grille directs air and prevents entry of larger objects.

Heat Exchanger heat-exchanger – Portion of a combustible furnace(Gas or Oil) that transfers heat to be expelled by the unit.

Heat Pump HP-Right Quarter– Outdoor unit that has a compressor to cycle hot and cold refrigerant. Transfers heat from one area to a cooler area.

HSPF – Heating Seasonal Performance Factor. Used to measure the heating efficiency of air source heat pumps. Higher the number, the more efficient the unit.


Indoor Air Quality (IAQ) – Term used to refer to air quality inside a building or structure. It commonly relates to the health and comforts of the occupants inside the building.

Packaged Unit daikin-package-unit – An air handler specially designed for outdoor installation with ducts that run into a structure. They normally contain both the heating and cooling portions of the system.

Plenum custom-plenum-chamber– Metal boxes attached to an indoor system. Airflow is then distributed from the plenum into ductwork.


Refrigerant 410-a– A mixture that changes from a liquid to gas to transfer heat from one place to another.

Seer – Seasonal Energy Efficiency Ratio. Cooling performance rating system for Air Conditioners and Heat Pumps. Higher the rating, the more efficient the system.

Split System Group Right– Combination of an outdoor unit and an indoor unit. Most common type of system.

System – General term referring to a unit that performs a specific HVAC function.

Thermostat  Honeywell Pro 8000 – Monitor and regulator of a heating and cooling system. Used to set a desired temperature.

Thermostatic Expansion Valve(TXV or TEV)  TXV – A piece of equipment that meters the flow of liquid refrigerant entering an evaporator while measuring the vapor refrigerant leaving the evaporator.

Two-Stage – System designed to operate on a high and low setting during different demands placed upon the system.

Zoning  zoning-system – Created section of a building or space that are controlled independently of each other. Different sections then can have own desired temperature using independent thermostats.