2,400+ Definitions

HVAC GLOSSARY

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

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R-422D
R-422D is a non-ozone-depleting hydrofluorocarbon (HFC) refrigerant blend developed as…
R-427A
R-427A, commonly marketed under the trade name Forane 427A or…
R-434A
R-434A is a hydrofluorocarbon/hydrofluoro-olefin (HFC/HFO) blend refrigerant developed as a…
R-438A
R-438A, commercially known as MO99, is a hydrofluorocarbon (HFC) blend…
R-448A
R-448A is a low-global-warming-potential (GWP) hydrofluoroolefin (HFO) blend refrigerant designed…
R-449A
R-449A is a non-flammable HFO-based refrigerant blend designed as a…
R-450A
R-450A is a non-ozone depleting hydrofluoro-olefin (HFO) blend refrigerant marketed…
R-452A
R-452A is a hydrofluoroolefin (HFO)-based refrigerant blend designed as a…
R-452B
R-452B is a low-GWP replacement refrigerant for R-410A and R-32…
R-454A
R-454A is a non-ozone depleting, low-GWP hydrofluoroolefin (HFO) blend refrigerant…
R-454B
R-454B (brand name Opteon XL41, manufactured by Chemours) is the…
R-454C
R-454C is a near-azeotropic HFO refrigerant blend with a GWP…
R-455A
R-455A, marketed under the trade name Solstice® LBA, is a…
R-466A
R-466A is a non-flammable, zeotropic refrigerant blend developed as a…
R-470A
R-470A is a zeotropic, non-ozone depleting refrigerant blend composed of…
R-513A
R-513A is a non-ozone depleting, HFO-based refrigerant blend consisting of…
R-515B
R-515B is a hydrofluoroolefin (HFO) refrigerant blend composed of R-1234ze(E)…
R-600a
R-600a, also known as isobutane, is a natural hydrocarbon (HC)…
R-717
R-717, also known as ammonia (NH3), is a natural refrigerant…
R-744
R-744, commonly known as carbon dioxide (CO2), is a natural…
Radiant Ceiling Panel
A radiant ceiling panel is a heating and cooling system…
Radiant Floor Heating
Radiant floor heating (RFH) is a space-heating method that employs…
Radiant Panel
A radiant panel is a heat transfer device engineered to…
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…
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 System
A recirculation system continuously circulates hot water through supply lines…
Rectangular Duct
Rectangular duct is a type of HVAC ductwork defined by…
Refrigerant
Refrigerant is the working fluid in an HVAC or refrigeration…
Refrigerant Blend
A refrigerant blend is a mixture of two or more…
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 Charging
Refrigerant charging is the process of adding the correct amount…
Refrigerant Cylinder
A refrigerant cylinder is a pressurized metal container specifically designed…
Refrigerant Detector Alarm
A refrigerant detector alarm is a safety device that continuously…