2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
Feed In Tariff
A feed-in tariff (FIT) is a government-backed policy that requires…
Fiberglass Filter
Fiberglass filters use spun glass fibers as the primary filtration…
Fill Factor
Fill factor (FF) is a percentage expressing the ratio between…
Filter Bypass
Filter bypass occurs when unfiltered air passes around a filter…
Filter Change
Filter Change is the replacement of furnace and air conditioning…
Filter Drier
A filter drier is a sealed component in the refrigerant…
Filter Efficiency
Filter efficiency measures the percentage of airborne particles that a…
Filter Housing
Filter housing is the structural enclosure that holds and secures…
Filter Life
Filter life is the duration a filter remains effective before…
Filter Pressure Drop
Filter pressure drop is the resistance created by a filter…
Filter Rack
A filter rack is the structural housing that holds an…
Filter Replacement
Filter replacement is the process of removing a used filter…
Fin Comb
A fin comb is a lightweight hand tool with multiple…
Fin Material
Fin material refers to the metal composition used in heat…
Fin Spacing
Fin spacing is the distance (measured in fins per inch)…
Fin Tube Radiation
Fin tube radiation refers to heating equipment where multiple fins…
Fire Damper
A fire damper is a safety device installed in ductwork…
First Air Conditioner
The first air conditioner was invented by Willis Carrier in…
First Hour Rating
First Hour Rating (FHR) measures the total volume of hot…
First Law of Thermodynamics
The First Law of Thermodynamics, also called the law of…
Flammable Refrigerant
A flammable refrigerant is any working fluid used in HVAC…
Flare Fitting
A flare fitting is a mechanical connection that uses a…
Flaring
Flaring is a tube-joining technique that creates a 45-degree conical…
Flash Gas
Flash gas is vapor that forms when high-pressure liquid refrigerant…
Flash Point
Flash point is the lowest temperature at which a volatile…
Flash Point Refrigerant
Flash point for refrigerants is the lowest temperature at which…
Flat Plate Collector
A flat plate collector is the most common solar thermal…
Flat Rate Electric
Flat rate electric pricing charges a consistent per-kilowatt-hour (kWh) rate…
Flat Rate Pricing
Flat rate pricing is a service pricing method where HVAC…
Flex Duct
Flex duct is a flexible, insulated ductwork made from a…
Flexible Connection HVAC
A flexible connection is a ductwork or piping joint using…
Flexible Connector
A flexible connector is a short hose or corrugated metal…
Float Switch
A float switch is a safety device that detects water…
Float Valve
A float valve is a mechanical valve that uses a…
Floating Control
Floating control is a two-position or three-position control strategy where…
Flooding
Flooding occurs when liquid refrigerant enters the compressor cylinder instead…
Floor Furnace
A floor furnace is a self-contained, gas-fired heating appliance designed…
Floor Mounted Unit
A floor mounted unit is an HVAC terminal device designed…
Flooring Emissions
Flooring emissions are volatile organic compounds and formaldehyde released from…
Flow Diagram
A flow diagram illustrates the movement of fluids or gases…
Flow Hood Measurement
A flow hood is a portable testing device that measures…
Flow Hood Measurement Tool
A flow hood is a large fabric hood that captures…
Flow Meter
A flow meter is an instrument that measures the volume…
Flue Gas Analysis
Flue gas analysis measures the chemical composition of gases exiting…
Flue Gas Analyzer
A flue gas analyzer measures combustion byproducts in heating system…
Flue Inspection
A flue inspection examines the ductwork and passages that carry…
Fluid Cooler
A fluid cooler is an air-cooled heat exchanger that removes…
Fluorescent Leak Dye
Fluorescent leak dye is a visible tracer chemical added to…