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
Refrigeration Effect
The refrigeration effect is the amount of useful cooling capacity…
Refrigeration Load
Refrigeration load is the total amount of heat that a…
Refrigeration System
A refrigeration system is a mechanical apparatus that transfers heat…
Relative Humidity
Relative humidity is the ratio of water vapor pressure in…
Relay
A relay is an electromechanical or solid-state switch that uses…
Relief Valve
A relief valve is a safety device that automatically opens…
Remote HVAC Control
Remote HVAC control allows users to adjust heating, cooling, and…
Renewable Energy
Renewable energy is power generated from naturally replenishing sources such…
Renewable Energy Certificate
A Renewable Energy Certificate (REC) is a market-based instrument that…
Reset Schedule
A reset schedule automatically adjusts HVAC setpoints based on outdoor…
Residential Solar
Residential solar refers to rooftop or ground-mounted photovoltaic systems installed…
Retro Commissioning
Retro commissioning is a systematic process of identifying and correcting…
Retrofit
A retrofit is the modification or replacement of existing HVAC…
Return Air Grille
A return air grille is a ventilation component installed over…
Return Duct
Return ducts transport air from occupied spaces back to the…
Reverse Return
A reverse return piping configuration routes the return water line…
Reversing Valve
A reversing valve is an electromechanical device installed in heat…
Reversing Valve Failure
Reversing valve failure occurs when the component that switches between…
Revit MEP
Revit MEP is Autodesk’s specialized BIM software designed for mechanical,…
Rigid Foam Board
Rigid foam board is a lightweight sheet insulation material manufactured…
Riser Diagram
A riser diagram is a vertical representation of piping or…
Rolling Brownout
A Rolling Brownout is a temporary, rotating reduction in electrical…
Roof Mount Solar
Roof mount solar refers to photovoltaic panels installed directly on…
Roof Reflectance
Roof reflectance, also called albedo, measures the percentage of solar…
Rooftop Equipment
Rooftop equipment includes HVAC units, cooling towers, air handling units,…
Rooftop Unit
A Rooftop Unit (RTU) is a self-contained heating, ventilation, and…
Room Air Cleaner
A room air cleaner is a portable or wall-mounted device…
Room Air Distribution
Room air distribution describes the movement and mixing patterns of…
Room Occupancy Detection
Room occupancy detection uses sensors to identify whether spaces are…
Rotating Vane Anemometer
A rotating vane anemometer measures air velocity through a calibrated…
Round Duct
Round duct is cylindrical metal tubing used to distribute conditioned…
RTD Sensor
An RTD (Resistance Temperature Detector) sensor measures temperature by monitoring…
Rubber Isolator
A rubber isolator is a resilient elastomer element that absorbs…
Runaround Coil
A runaround coil system consists of two heat exchanger coils…
Runway Damper
A runway damper is a fire damper engineered to compartmentalize…