2,400+ Definitions

HVAC GLOSSARY

Every HVAC term, acronym, and industry phrase — defined in plain English.

All A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Fossil Fuel Switchover Point
The specific outdoor temperature at which a dual-fuel system’s controls…
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…
Four-Pipe System
A hydronic distribution arrangement that maintains dedicated supply and return…
fractionation
The separation of refrigerant blend components in the liquid and…
Framing Factor
The fraction of a wall or roof assembly cross-section occupied…
Free Cooling
Free cooling leverages outdoor air or water sources to remove…
Free Cooling (Waterside)
A mode of chiller plant operation in which cool ambient…
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…
Friction Rate
Friction rate is the pressure loss per 100 feet of…
Frost Control Mode
An operational strategy used in HRVs and ERVs during very…
Frost-Free Evaporator
An evaporator coil designed and operated with periodic automatic defrost…
Full Load Amps
Full Load Amperage (FLA) is the continuous electrical current a…
Fume Hood
A fume hood is a laboratory ventilation device that captures…
Functional Test
A functional test is a procedure verifying individual HVAC components…
Furnace
A furnace is a forced-air heating system that burns fuel…
Furnace Installation
Furnace installation involves mounting a gas or electric heating unit…
Furniture Off Gassing
Furniture off gassing is the release of volatile organic compounds…
Fuse
A fuse is an overcurrent protection device that contains a…
Galvanized Pipe
Galvanized pipe is steel tubing coated with a protective zinc…
gas cooler
A heat exchanger used in transcritical CO2 refrigeration systems to…
Gas Furnace
A gas furnace is a heating appliance that burns natural…
Gas Phase Filtration
Gas phase filtration is a specialized air treatment process that…
Gas Pressure Manometer
A precision low-pressure instrument used to measure natural gas or…
Gas Valve
A gas valve is an electronically controlled device that regulates…
Gas Water Heater
A gas water heater uses natural gas or propane fuel…
Gate Valve
A gate valve is a linear flow control device that…
Gate Valve Plumbing
A gate valve is a shutoff valve that uses a…
Geofencing HVAC
Geofencing HVAC is a location-based control technology that uses smartphone…
Geothermal Heat Pump
A geothermal heat pump (GHP), also called a ground-source heat…
Geothermal Installation
Geothermal installation involves drilling ground loops and connecting them to…
Germicidal UV
Germicidal UV (ultraviolet-C light at 254 nanometers wavelength) destroys microorganism…
GFCI
GFCI stands for Ground Fault Circuit Interrupter, a critical safety…
Gigawatt
A gigawatt (GW) is a unit of power equal to…
Global Warming Potential Limit
A Global Warming Potential (GWP) Limit is a regulatory threshold…
Globe Valve
A Globe Valve is a linear-motion shutoff valve with an…
Glycol
Glycol is an organic antifreeze and heat transfer fluid used…
Glycol Chiller
A glycol chiller is a refrigeration system that circulates a…
Glycol Percentage
The concentration of ethylene or propylene glycol in a hydronic…
Glycol Runaround
A glycol runaround system circulates a water-glycol mixture through two…
Glycol Secondary Loop
A refrigeration system configuration in which a chilled glycol and…
Google Home HVAC
Google Home HVAC enables control of heating and cooling systems…
GPM
GPM stands for gallons per minute, a measurement of fluid…