2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
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…
Fin-Tube Baseboard
A hydronic terminal unit consisting of a copper or steel…
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…
Fixed Plate Heat Exchanger
A stationary core heat recovery device made of parallel plates…
Flame Rectification
A flame-sensing method that exploits the asymmetric electrical conductivity of…
Flame Rollout
A dangerous condition in which flames escape the combustion chamber…
Flammable Refrigerant
A flammable refrigerant is any working fluid used in HVAC…
Flare Connection
A mechanical refrigerant pipe joint made by forming the end…
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 Injection
A technique used in cold-climate heat pump compressors where a…
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…
Flash Tank Economizer
A type of vapor injection system that uses a flash…
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…
Floating Head Pressure Control
A control strategy that allows condensing pressure to drop as…
Flooded Evaporator
A shell-and-tube or shell-and-plate evaporator in which the refrigerant fills…
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…
Floor-Console Indoor Unit
A ductless indoor unit designed to mount at floor level…
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…
Flow Straightener
A device inserted in a duct consisting of parallel tubes,…
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 Gas Dew Point
The temperature at which water vapor in combustion exhaust gases…
Flue Gas Recirculation
A combustion control technique that routes a portion of exhaust…
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 Dye Leak Detection
A method of leak location in which a UV-fluorescent dye…