HVAC Glossary

Alternative HVAC Solutions would like to offer the following HVAC Glossary as a helpful tool for you, our customer, to help with the various terms and technical definitions for the heating, cooling and indoor air quality industry.

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Fahrenheit -  (F) A temperature scale in which the boiling point of water is 212 degrees and its freezing point is 32 degrees. To convert Fahrenheit to Celsius, subtract 32, multiply by 5, and divide the product by 9. For example: 100 degrees Fahrenheit - 32 = 68; 68 x 5 = 340; 340 / 9 = 37.77 degrees Celsius.
Fan Coil -  An indoor component of a heat pump system used in place of a furnace, to provide additional heating on cold days when the heat pump does not provide adequate heating. A component of a heating, ventilation and air conditioning (HVAC) system containing a fan and heating or cooling coil, used to distribute heated or cooled air.
FAQ -  (Frequently Asked Questions) Used to mean a list of frequently asked questions.
Filter -  A device for removing dust particles from air or unwanted elements from liquids.
Fire Valves -  (or Fire Dampers) Components which are installed in an air distribution system between two fire separating compartments and are designed to prevent propagation of fire and/or smoke. Generally are kept open by mechanical restraint, whose effect is canceled under specific conditions. The valve is then closed automatically.
Flame roll-out -  A dangerous situation that occurs when flame is pushed out of the bottom of a combustion appliance. It can lead to fires.
Flex duct -  Usually installed in a single, continuous piece between the register and plenum box, a flexible duct usually has an inner lining and an insulated coating on the outside.
Flow Hood -  A diagnostic tool used to measure air flow through ducts, supply registers, and return grilles. Device that easily measures airflow quantity, typically up to 2,500 cfm.
Follow-Up Testing -  The testing designed to confirm the results of the initial testing using identical testing devices and similar test conditions.
Forced Air -  This describes a type of heating system that uses a blower motor to move air through the furnace and into the ductwork. Heating and or cooling system that connects to the conditioned space with duct-work that uses air as the moving fluid. The heating or cooling can come from any number of sources.
Forced Air Unit -  (FAU) A central furnace equipped with a fan or blower that provides the primary means for circulation of air.
Formaldehyde -  Formaldehyde is a colorless water-soluble gas. Due to its wide use, it is frequently considered separately from other volatile organic compounds (VOCs)
Frequency -  The number of cycles which an alternating current moves through in each second. Standard electric utility frequency in the United States is 60 cycles per second, or 60 Hertz.
Fungi -  A large group of organisms including molds, mildews, yeasts, mushrooms, rusts, and smuts. Any of a group of parasitic lower plants that lack chlorophyll. Most fungi produce spores, which are broadcast through the air so that virtually all environmental surfaces will have some fungal material. Most health effects are associated with allergic responses to antigenic material or toxic effects from mycotoxins. Fungi also generate certain volatile organic compounds.
Fungicide -  Substance or chemical that kills fungi.
Furnace -  That part of an environmental system which converts gas, oil, electricity or other fuel into heat for distribution within a structure.
Furnace, Horizontal -  A furnace that lies on its side, pulling in return air from one side and expelling warm air from the other.