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
TXV
A thermostatic expansion valve (TXV) is a precision refrigerant metering…
TXV (Thermostatic Expansion Valve)
A Thermostatic Expansion Valve (TXV, also TEV) is a refrigerant…
Type B Vent
Type B vent is a double-wall metal pipe designed for…
Type I Certification
Type I Certification authorizes technicians to service small appliances containing…
Type I Hood
A Type I hood is a grease-capturing exhaust hood specifically…
Type II Certification
Type II Certification authorizes technicians to service large appliances and…
Type II Hood
A Type II hood is a ventilation hood designed for…
Type III Certification
Type III Certification authorizes technicians to service high-pressure air conditioning…
Typical Meteorological Year
Typical Meteorological Year (TMY) represents a complete 12-month weather dataset…
U Value
U Value measures the overall rate of heat transfer through…
UEF
UEF stands for Uniform Energy Factor, the standardized efficiency rating…
UL 1995
UL 1995 is the safety standard for commercial and industrial…
UL 207
UL 207 is a safety standard published by Underwriters Laboratories…
UL 303
UL 303 is a safety standard published by Underwriters Laboratories…
UL 4811
UL 4811 is the safety standard for solar photovoltaic (PV)…
ULPA Filter
ULPA (Ultra-Low Penetration Air) filters capture 99.99% of particles at…
Ultrasonic Leak Detector
An ultrasonic leak detector identifies refrigerant leaks by sensing the…
UMC
Definition The Uniform Mechanical Code (UMC) is a model building…
Undercut Door
An undercut door is a door that has been intentionally…
Underfloor Air Distribution
Underfloor Air Distribution (UFAD) is an air delivery strategy in…
Unidirectional Airflow
Unidirectional airflow describes air movement in a single, consistent direction…
Uniform Energy Factor
Uniform Energy Factor (UEF) is the current standardized efficiency metric…
Unit Heater
A unit heater is a self-contained heating device that combines…
Unitary System
A unitary system is a self-contained HVAC assembly in which…
Universal Certification
Universal Certification, also called Type IV certification, authorizes technicians to…
Unoccupied Mode
Unoccupied Mode is a reduced-operation setting where HVAC systems operate…
Upper Room UVGI
Upper room UVGI (ultraviolet germicidal irradiation) is a disinfection technique…
Utility API
A utility API is an application programming interface that allows…
Utility DSM
Utility DSM refers to demand-side management programs operated by electric…
Utility Grid
The utility grid is the complete electrical distribution network operated…
Utility Interconnection Agreement
A utility interconnection agreement is a legally binding contract between…
Utility Rate Schedule
A utility rate schedule is the official document filed with…
Utility Rebate Program
A Utility Rebate Program offers financial incentives provided by electric,…
Utility Scale Solar
Utility-scale solar refers to large photovoltaic power plants ranging from…
UV Air Purifier
A UV air purifier uses ultraviolet light radiation to inactivate…
UV Drain Treatment
UV drain treatment uses ultraviolet light technology installed in condensate…
UV Dye
UV dye (ultraviolet fluorescent dye) is a tracer chemical injected…
UV Germicidal Irradiation
UV germicidal irradiation (UVGI) is a disinfection technology using ultraviolet…
UVC Lamp Life
UVC lamp life refers to the operational duration of ultraviolet…
UVGI Efficacy
UVGI efficacy measures the effectiveness of ultraviolet germicidal irradiation systems…
UVGI Safety
UVGI safety encompasses protective measures and exposure limits established to…
Vacuum Procedure
The vacuum procedure removes air, moisture, and other non-condensables from…
Vacuum Pull Down
Vacuum pull down is a test that measures how quickly…
Valve Actuator
A valve actuator is a device that opens, closes, or…
Valve Authority
Valve authority is a dimensionless ratio that measures a control…
Valve Sizing
Valve sizing is the process of selecting a control valve…
Vane Anemometer
A vane anemometer measures air velocity using multiple propeller-like blades…
Vapor Barrier
A vapor barrier is a material with a permeance rating…