A Glossary of HVAC Terms ABCDEFGHIJKLMNOPQRSTUVWXYZ A AFUE Air changes per hour Air cleaner Air conditioner Air filtration system Air handler Air handler, air handling unit All-in-one system Allergen Back to top B British thermal unit (BTU) BTU Back to top C Capacity Centrifugal fan CFM Chiller Coil Compressor Condenser Condenser coil Constant air volume Control Controller Cycling Back to top D Damper Deep lake water cooling Dehumidifier Delta T (?T) Diffuser Dry bulb temperature Dry bulb thermometer Duct Ductwork Back to top E Economizer Energy Star® Enthalpy Evaporator Back to top F Fan coil unit Flow Fresh air fan Fresh air fraction Fresh air intake Furnace Back to top G Gas furnace heat exchanger Grille Back to top H Heat exchanger Heat gain, heat load, heat loss Heat pump Heat transfer Heating coil Hepa filter Home automation HSPF Hspf – (heating seasonal performance factor) Humidifier Humidity HVAC Hybrid comfort system Back to top I Indoor coil Indoor/outdoor system Industrial refrigerator Intermediate fluid Back to top L Load calculation Back to top M Makeup air unit Matched system Minimum outside air Modulating heating Back to top N NATE Back to top O Outdoor coil Outdoor unit Outside air damper Outside air temperature Back to top P Packaged system Packaged terminal air conditioner Packaged unit Plenum space Psychrometric Back to top R Radiant ceiling panels Radiant floor Radiation Refrigerant Rooftop unit (RTU) Back to top S SEER SEET Smart home Smoke damper Split system Subcooling Superheat Back to top T Terminal unit Thermal zone Thermostat Two-stage (cooling and heating) Two-stage heating / two-stage cooling TXV – thermostatic expansion valve Back to top U Underfloor air distribution Unitary controller Back to top V Variable air volume Variable-speed motor Back to top Z Zoning system Back to top