2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
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…
Vapor Compression Cycle
The vapor compression cycle is the thermodynamic process used by…
Vapor Compression Refrigeration
Vapor compression refrigeration is the dominant cooling technology that uses…
Vapor Injection
Vapor injection is an advanced refrigeration technique that injects high-pressure…
Vapor Pressure
Vapor pressure is the pressure exerted by a vapor in…
Vapor Retarder
A vapor retarder is a material with permeance ratings between…
Variable Air Volume
Variable Air Volume (VAV) is an HVAC system design that…
Variable Capacity System
A Variable Capacity System is an HVAC system designed to…
Variable Flow
Variable flow hydronic systems adjust circulation pump speed and water…
Variable Frequency Drive
A Variable Frequency Drive (VFD) is an electronic controller that…
Variable Frequency Drive (VFD)
A Variable Frequency Drive (VFD) is an electronic controller that…
Variable Pitch Fan
A variable pitch fan (VPF) is an axial fan designed…
Variable Refrigerant Flow
Variable Refrigerant Flow (VRF) is an advanced HVAC technology that…
Variable Setpoint
A variable setpoint is a target temperature that automatically adjusts…
Variable Speed Drive
A variable speed drive (VSD) is an electronic controller that…
Variable Speed Motor
A variable speed motor (also called an ECM — Electronically…
Variable Torque Load
A variable torque load is a mechanical resistance that increases…
VAV Box
A Variable Air Volume (VAV) box is an HVAC terminal…
Ventilation
Ventilation is the controlled exchange of indoor and outdoor air,…
Ventilation Effectiveness
Ventilation effectiveness measures how efficiently a ventilation system removes contaminants…
Ventilation Rate Procedure
The Ventilation Rate Procedure is a prescriptive ASHRAE 62.1 method…
Verification Testing
Verification testing in HVAC refers to the systematic process of…
Very High Pressure Category
The Very High Pressure Category includes systems operating at pressures…
VFD
A Variable Frequency Drive (VFD) is an electronic device used…
Vibration Analysis Maintenance
Vibration analysis maintenance measures mechanical vibration in compressors, motors, and…
Vibration Analyzer
A vibration analyzer is a sophisticated diagnostic instrument that measures…
Vibration Isolation Pad
A vibration isolation pad is a resilient material placed under…
Vibration Isolator
A vibration isolator is a mechanical device engineered to reduce…
Vibration Meter
A vibration meter is a portable instrument that measures mechanical…
Virtual Islanding
Virtual islanding is a control strategy that allows a grid-connected…
Virtual Net Metering
Virtual net metering allows customers to receive bill credits for…
Virtual Power Plant
A virtual power plant is a network of distributed energy…
VOC
Volatile organic compounds (VOCs) are carbon-containing chemicals that evaporate at…
VOC Monitor
A VOC monitor detects volatile organic compounds in indoor air,…
Volatile Organic Compound
Volatile Organic Compounds (VOCs) are carbon-containing chemicals that evaporate at…
Volatile Organic Compound Sources
Volatile Organic Compound (VOC) Sources are materials and products that…
Volt
A volt (V) is the unit of electrical potential difference…
Volume Damper
A volume damper is a manually or electronically adjustable valve…
VRF System
VRF (Variable Refrigerant Flow) is a sophisticated HVAC technology used…