2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
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…
Flush Mount Solar
Flush mount solar describes panels installed parallel to roof surfaces…
Flushing
Flushing is the process of circulating a cleaning agent or…
Foaming Coil Cleaner
Foaming coil cleaner is a specialized chemical product that expands…
Food Service HVAC
Food service HVAC systems manage temperature, humidity, and air quality…
Forced Air Furnace
A forced air furnace is a heating system that uses…
Forced Draft Cooling Tower
A forced draft cooling tower uses a fan mounted at…
Formaldehyde
Formaldehyde is a colorless, pungent gas released from building materials,…
Formaldehyde Sources
Formaldehyde Sources are building materials and furnishings that emit formaldehyde…
Four Pipe System
A four-pipe system is a hydronic HVAC distribution configuration that…
Four Way Reversing Valve
A four-way reversing valve is an electromechanical component used in…
Free Cooling
Free cooling leverages outdoor air or water sources to remove…
Free Cooling Coil
A free cooling coil transfers heat directly from a building…
Free Cooling Mode
Free Cooling Mode uses available outdoor air or water resources…
Freeze Up
Freeze up occurs when ice accumulates on the evaporator coil,…
Freezer
A freezer is a refrigeration appliance or system that maintains…
Freon History
Freon is the trademark name for chlorofluorocarbon (CFC) refrigerants developed…
Fresh Air Intake
A fresh air intake brings outdoor air into the HVAC…