2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
Radiant Time Factor
A coefficient in the radiant time series method representing the…
Radiant Time Series Method
An ASHRAE load calculation procedure that separates instantaneous heat gain…
Radiant Tube Heater
A radiant tube heater is an industrial heating system consisting…
Radiation
Radiation is heat transfer through electromagnetic waves that requires no…
Radon
Radon is a colorless, odorless, radioactive gas that seeps into…
Range Hood
A range hood is an exhaust ventilation system installed above…
Range Temperature
Range temperature is the difference between the hot water entering…
Rankine Cycle
The Rankine cycle is a thermodynamic process describing how steam…
RC Curve
An RC curve is an alternative noise rating system that…
Reach Code
A Reach Code is a local or regional energy code…
Reach In Cooler
A reach-in cooler is a self-contained refrigeration unit with front-opening…
Reach-In Refrigerator
A self-contained or remotely connected commercial refrigerator designed for a…
Reactive Power
Reactive power is the portion of electrical power that oscillates…
Real Power
Real power is the actual electrical power consumed by HVAC…
Real Time Pricing
Real time pricing (RTP) is a utility billing model where…
Rear Door Heat Exchanger
A Rear Door Heat Exchanger is a cooling device mounted…
Rebate Program
Rebate programs are incentive offerings from utilities, government agencies, and…
REC
REC is the abbreviation for Renewable Energy Certificate, a tradable…
Receiver
A receiver is a cylindrical pressure vessel installed in the…
Recirculation Credit
A reduction in required outdoor airflow allowed by ASHRAE 62.1…
Recirculation System
A recirculation system continuously circulates hot water through supply lines…
Recovery Cylinder
A DOT-approved pressure vessel specifically designed and color-coded (gray body,…
Recovery Machine
A motor-driven unit that removes refrigerant from a system and…
Rectangular Duct
Rectangular duct is a type of HVAC ductwork defined by…
Refractory
High-temperature ceramic or mineral wool material lining the combustion chamber…
Refrigerant
Refrigerant is the working fluid in an HVAC or refrigeration…
Refrigerant Blend
A refrigerant blend is a mixture of two or more…
refrigerant blend composition shift
A change in the ratio of components in a zeotropic…
Refrigerant Brazing
Refrigerant brazing is the process of joining copper tubing using…
Refrigerant Charge
Refrigerant charge refers to the specific amount of refrigerant in…
Refrigerant Charge Adjustment
The process of adding or removing refrigerant from a VRF…
Refrigerant Charging
Refrigerant charging is the process of adding the correct amount…
Refrigerant Cylinder
A refrigerant cylinder is a pressurized metal container specifically designed…
Refrigerant Cylinder Tare Weight
The empty weight of a refrigerant cylinder stamped on its…
Refrigerant Detector Alarm
A refrigerant detector alarm is a safety device that continuously…
Refrigerant Distributor
A refrigerant distributor is a device installed between an expansion…
Refrigerant GWP
Refrigerant GWP (Global Warming Potential) is a numerical rating measuring…
Refrigerant Identifier
A portable analyzer that samples a refrigerant blend and uses…
Refrigerant Leak
A refrigerant leak occurs when the sealed cooling system loses…
Refrigerant Leak Check Annual
An annual refrigerant leak check is a professional inspection using…
Refrigerant Leak Detection
Refrigerant leak detection is the process of locating refrigerant leaks…
Refrigerant Leak Sensor
A refrigerant leak sensor detects and alerts operators to the…
Refrigerant Line Set
A refrigerant line set is a pair or trio of…
Refrigerant Log
A Refrigerant Log is a detailed record documenting all refrigerant…
Refrigerant Loop Subcooling
The process of cooling liquid refrigerant below its saturation temperature…
Refrigerant Management Plan
A Refrigerant Management Plan is a documented strategy that outlines…
Refrigerant Migration
The movement of liquid refrigerant from the evaporator or other…
Refrigerant ODP
Refrigerant ODP (Ozone Depletion Potential) is a relative measure of…