HVAC Acronyms: What They Stand For - Heating and Cooling USA

HVAC, an abbreviation for Heating, Ventilation, and Air Conditioning, is just one of many acronyms with full forms worth remembering. To make communication between homeowners and the HVAC industry easier, we have built a list for quickly retrieving any HVAC abbreviation with the term’s full form. Below is a table of 700 HVAC abbreviations and each term’s associated full form. Use the search function to quickly retrieve any abbreviation from the list.

Abbreviation	Full Form
°F	Degrees Fahrenheit
A	Air / Compressed Air / Compressed Air Line / Area
AB	Above
A/C	Air Conditioning
AC	Air Curtain / Air Chamber / Alternating Current
ACC	Air Cooled Condenser
ACCU	Air Cooled Condensing Unit
ACD	Automatic Control Damper
ACH	Air Changes Per Hour
ACM	Asbestos Containing Material
ACU	Air Conditioning Unit
AD	Access Door (Duct or Plenum)
ADU	Accessory Dwelling Unit
AE	Acoustical Elbow
AEE	Association Of Energy Engineers
AF	Air Foil
AFD	Adjustable Frequency Drive
AFF	Above Finished Floor
AFG	Above Finished Grade
AFMS	Air Flow Monitor / Measuring Station
AFP	Air Flow Measurement Probe
AFUE	Annual Fuel Utilization Efficiency
AHRI	Air Conditioning, Heating, And Refrigeration Institute
AHU	Air Handling Unit - May be used interchangeably with ADU And ARU.
AI	Analog Input
AL	Aluminum / Acoustical Lining
ALT	Alternate/Alternative
AMB	Ambient
AMP	Ampere
AO	Analog Output
AP	Access Panel
APD	Air Pressure Drop
AR	Acid Resistant
ARR	Arrangement
ARU	Air Rotation Unit / Air Refrigeration Unit
ARV	Air Relief Valve / Manual Air Vent
AS	Air Stream / Air Separator
ASHRAE	American Society Of Heating Refrigeration And Air Conditioning Engineers
ASME	American Society Of Mechanical Engineers
ASTM	American Society For Testing And Materials
AT	Air Transfer
ATC	Automatic Temperature Control
ATD	Air Temperature Drop (in °F)
ATM	Atmosphere
ATV	Air Turning Vanes
AUTO	Automatic
AUX	Auxiliary
AVE	Air Volume Extractor
AVG	Average
B	Boiler
BACNET	A Data Communication Protocol For Building Automation And Control Networks
BAS	Building Automation System
BBD	Boiler Blowdown
BCA	Building Commissioning Association
BCP	Boiler Circulation Pump
BD	Balancing Damper / Barometric Damper / Barometric Counter Balanced Gravity Operated Damper
BDD	Back Draft Damper
BF	Boiler Feed
BG	Barrier Grill
BHP	Brake Horsepower / Boiler Horsepower
BI	Backward Incline
BLDG	Building
BLR	Boiler
BMCS	Building Management System
BMS	Building Management System
BO	Blank Off / Binary Output
BOD	Bottom Of Duct/Bottom of Device (in Units)
BOP	Bottom Of Pipe
BOT	Bottom
BP	Back Pressure
BSLN	Baseline
BSMT	Basement
BTU	British Thermal Unit
BTUH	British Thermal Units Per Hour
BU	Blower Unit
BV	Butterfly Valve
BY	Base Year
C	Celsius / Condensate Line
C TO C	Center To Center
C/W	Complete With
CA	Compressed Air
CAL	Calorie
CAP	Capacity
CAU	Combustion Air Unit
CAV	Constant Air Volume Box
CBP	Chilled Beam, Passive
CC	Cooling Coil
CCP	Coil Circulation Pump
CCU	Closed Control Unit
CD	Ceiling Diffuser / Cold Deck / Condensate Drain / Control Damper
CDD	Cooling Degree Days
CDR	Condensate Drain Line
CEM	Certified Energy Manager
CENT	Center / Centrifugal
CF	Cubic Feet / Cubic Foot / Chemical Feed / Cartridge Filter
CFC	Chlorofluorocarbon
CFF	Cap For Future
CFH	Cubic Feet Per Hour
CFM	Cubic Feet Per Minute
CG	Ceiling Grille
CH	Chiller / Chilled
CHLR	Chiller
CHP	Chilled Water Pump
CHR	Chilled Water Return
CHS	Chilled Water Supply
CHW	Chilled Water
CHWP	Chilled Water Pump
CHWR	Chilled Water Return
CHWRT	Chilled Water Return Temperature
CHWS	Chilled Water Supply
CHWST	Chilled Water Supply Temperature
CI	Cast Iron
CIRC	Circular
CL	Center Line
CLF	Cooling Load Factor
CLG	Ceiling
CLTD	Cooling Load Temperature Difference
CM	Centimeter
CM2	Square Centimeter
CO	Clean Out / Carbon Monoxide
COL	Column
COMP	Compressor
CONC	Concrete / Concentric
COND	Condenser
CONN	Connect / Connection
CONT	Continuation
CONV	Convector
COP	Coefficient Of Performance
CP	Condensate Pump
CPVC	Chlorinated Polyvinyl Chloride
CR	Ceiling Register / Condenser Return
CRAC	Computer Room Air Conditioner
CRU	Computer Room Unit
CRW	Chemical Resistant Waste
CS	Condenser Supply
CSF	Chemical Shot Feeder
CSR	Current Sensing Relay
CT	Cooling Tower
CTBD	Cooling Tower Blow Down
CTR	Center
CU	Cubic / Cooling Unit / Condensing Unit
CU FT	Cubic Feet
CU IN	Cubic Inches
CUH	Cabinet Unit Heater
CV	Constant Volume / Check Valve / Convector
CVRMSE	Coefficient Of Variation Of The Root Mean Square Of The Error
CW	Condenser Water / Cold Water
CWP	Condenser Water Pump
CWR	Condenser Water Return
CWRT	Condenser Water Return Temperature
CWS	Condenser Water Supply
CWST	Condenser Water Supply Temperature
CY	Current Year
D	Deep or Drain
DA	Discharge Air
DB	Dry Bulb Temperature
DBT	Dry Bulb Temperature
DC	Dust Collector / Direct Current
DCV	Demand Controlled Ventilation
DCW	Domestic Cold Water
DD	Degree Day
DDC	Direct Digital Control
DEC	Direct Evaporative Cooler
DEG	Degree
DELTA T	Delta Temperature / Temperature Difference
DET	Detail
DH	Duct Heater
DHW	Domestic Hot Water
DI	Digital Input
DIA / Ø	Diameter
DIM	Dimension
DISC	Disconnect
DL	Door Louver
DN	Down
DO	Digital Output
DOAS	Dedicated Outdoor Air System
DP	Differential Pressure (in Feet Of Head, Unless Otherwise Noted)
DPS	Differential Pressure Switch
DPT	Dew Point Temperature
DR	Drain
DRV	Double Regulating Valve
DRX	Clothes Dryer Exhaust
DS	Duct Silencer
DT	Differential Temperature (in °f, Unless Otherwise Noted)
DU	Dehumidification Unit
DUC	Door Under Cut (in Inches, Unless Otherwise Noted)
DV	Displacement ventilation
DWG	Drawing
DX	Direct Expansion
E	Emergency Heating
E TO C	End To Center
E/P	Electrical/pneumatic
EA	Exhaust Air / Each
EAD	Exhaust Air Duct
EAG	Exhaust Air Grill
EAHU	Exhaust Air Handling Unit
EAL	Exhaust Air Louver
EAR	Exhaust Air Register
EAT	Entering Air Temperature
EATR	Exhaust Air Transfer Ratio
ECD	Exhaust Ceiling Diffuser
ECG	Exhaust Ceiling Grill
ECH	Electric Cabinet Heater
ECM	Electronically Commutated Motor
ECO	Energy Conservation Opportunity
ECON	Economizer
EDB	Entering Drying Bulb
EDH	Electric Duct Heater
EEM	Energy Efficiency Measure
EER	Energy Efficiency Ratio
EF	Exhaust Fan
EFF	Efficiency
EG	Exhaust Grille
EH	Electric Heater
EHC	Electric Heating Coil
EJ	Expansion Joint
EL	Elevation
ELB	Elbow
ELEC	Electric, Electrical
ELEV	Elevation
ELSD	Exhaust Linear Slot Diffuser
EM	Expanded Metal (minimum Of 70% Free Area, Unless Otherwise
EMER	Emergency
EMS	Energy Management System
ENT	Entering
EP	Elevator Pressurization
EQUIP	Equipment
ERC	Energy Recovery Chiller
ERV	Energy Recovery Ventilator
ERW	Energy Recovery Wheel / Heat Enthalpy Wheel
ESCO	Energy Service Company
ESP	External Static Pressure
ET	Expansion Tank
EUH	Electrical Unit Heater
EVAP	Evaporator
EVV	Exhaust Venture Valve
EWB	Entering Wet Bulb
EWT	Entering Water Temperature
EX	Existing
EXF	Exhaust Fan

EXH or EX	Exhaust
EXP	Expansion
EXST	Existing
EXT	Exterior
F	Filter
F/SD	Combination Fire/smoke Damper
F&T	Float And Thermostatic Trap
FA	Free Area / Fire Alarm / From Above
FAD	Fresh Air Duct
FAF	Fresh Air Fan
FAHU	Fresh Air Handling Unit
FAI	Fresh Air Intake
FAL	Fresh Air Louver
FAR	Fresh Air Register
FB	From Below
FBO	Furnished By Others
FC	Fan Coil Unit
FCC	Fire Control Center
FCO	Floor Clean Out
FCU	Fan Coil Unit
FCV	Fan Coil Unit, For VRF Systems
FD	Fire Damper
FDW	Feed Water
FEC	Fire Extinguisher Cabinet
FF	Finish Floor
FG	Finish Grade
FHC	Fire Hose Cabinet
FIM	Facility Improvement Measure
FJ	Flexible Joint
FLA	Full Load Amps
FLEX	Flexible
FLR	Floor
FLRDR	Floor Drain
FM	Flow Meter
FMS	Facility Management System
FO	Fuel Oil
FOR	Fuel Oil Return
FOS	Fuel Oil Supply
FOV	Flush Out Valve
FP	Fire Protection
FPB	Fan Powered Box
FPI	Fins Per Inch
FPM	Feet Per Minute
FPS	Feet Per Second
FR	Filter Rack
FRE	Fire Rated Enclosure
FRP	Fiberglass Reinforced Plastic
FS	Flow Switch
FSD	Combination Fire and Smoke Damper
FT	Feet
FTG	Fitting
FTR	Fin Tube Radiation
FU	Fixture Unit
FV	Flush Valve
FW	Feed Water
G	Gas
GA	Gauge
GAL	Gallons
GALV	Galvanized
GC	Condensate Piping - Gravity Drainage
GF	Glycol Feeder
GFU	Glycol Feed Unit
GLR	Ground/geothermal Loop Return
GLS	Ground/geothermal Loop Supply
GLV	Gas Lift Valve
GLY	Glycol
GND	Ground
GPD	Gallons Per Day
GPH	Gallons Per Hour
GPM	Gallons Per Minute
GPS	Gallons Per Second
GR	Grade / Grain
GRD	Grills, Registers, and Diffusers
GUI	Graphical User Interface
GV	Gate Valve / Globe Valve
GWH	Gas Water Heater
GX	Garage Exhaust / General Exhaust
H2O	Water
HB	Hose Bib (connection)
HC	Heating Coil
HCFC	Hydrochlorocfuorocarbon
HD	Head
HDD	Heating Degree Days
HDG	Heavy Duty Grille
HEPA	High Efficiency Particulate Arresting
HEX	Heat Exchanger
HF	Hepa Filter
HFC	Hydrofluorocarbon
HG	Mercury
HGT	Height
HHR	Heating Hot Water Return
HHS	Heating Hot Water Supply
HHV	Higher Heating Value
HHWP	Heating Hot Water Pump
HHWR	Heating Hot Water Return
HHWS	Heating Hot Water Supply
HL	High Limit
HLS	High Limit Switch
HMD	Humidity
HORIZ	Horizontal
HP	Horsepower
HPR	Heat Pump Loop Return
HPS	Heat Pump Loop Supply
HPU	Heat Pump Air Handling Unit, Air Or Water Source
HPW	Water To Water Heat Pump Unit
HR	Heat Recovery
HRU	Heat Recovery Unit
HRV	Heat Recovery Ventilator
HSPF	Heating Seasonal Performance Factor
HSPF2	Heating Seasonal Performance Factor 2
HTD	Heated
HTG	Heating
HTP	Heat Pump
HTR	Heater
HTW	Heatwheel
HU	Humidistat
HV	Heating and Ventilation Unit
HVAC	Heating Ventilation And Air Conditioning
HVAC R, HVAC&R, or HVACR	Heating, Ventilation, Air Conditioning, and Refrigeration
HW	Hot Water
HWH	Hot Water Heater
HWP	Heating Hot Water Pump
HWR	Hot Water Return
HWRT	Hot Water Return Temperature
HWS	Hot Water Supply
HWST	Hot Water Supply Temperature
HWT	Hot Water Tank
HX	Heat Exchanger
HZ	Herts (cycles Per Second)
I/O	Input Output
IAQ	Indoor Air Quality
ID	Inside Diameter (in Inches, Unless Otherwise Noted)
IDEC	Indirect Evaporative Cooler
IH	Intake Hood
IN	Inch / Inches
INHG	Inches Of Mercury
INSUL	Insulation
INT	International
INTL	Internal
INV	Invert
IPMVP	International Performance Measurement And Verification Protocol
IPS	Iron Pipe Size
IR	Infra
IV	Indirect Vent
IW	Indirect Waste
J	Joule
K	Kelvin
KG	Kilogram
KH	Kitchen Hood
KM	Kilometer
KM2	Kquare Kilometer
KPA	Kilo Pascal
KS	Kitchen Sink
KW	Kilowatt
KWH	Kilowatt Hours
KX	Kitchen Exhaust
L	Length / Liter
LAT	Leaving Air Temperature
LB	Pound
LBF	Pound Force
LBS	Pounds
LD	Linear Diffuser (ceiling, wall, sill, or floor)
LF	Linear Feet
LHV	Lower Heating Value
LIQ	Liquid
LL	Low Level / Low Limit
LLS	Low Limit Switch
LON	Local Operating Network
LP	Liquid Petroleum
LPD	Lift Pressurization Duct
LPS	Low Pressure Steam
LRA	Lock Rotor Amps
LSD	Linear Slot Diffuser
LUVR or LVR	Louver
LVDR	Louvered Door
LVG	Leaving
LVL	Level
LVR	Louver
LWBT	Leaving Wet Bulb Temperature
LWS	Louver with Wire Screen
LWT	Leaving Water Temperature
M	Meter
M TYPE	Lightest Type Of Rigid Copper Pipe
M&V	Measurement And Verification
M2	Square Meter
MA	Mixed Air
MAN	Manual
MAT	Mixed Air Temperature
MAU	Makeup Air Unit
MAX	Maximum
MBH	Equivalent To 1,000 Btuh
MCA	Minimum Circuit Amps
MCC	Motor Control Center
MECH	Mechanical
MFR	Manufacturer
MFR or MFG	Manufacturer
MFS	Maximum Fuse Size
MG	Milligram
MGD	Millions Gallons Per Day
MH	Manhole
MIN	Minimum
MISC	Miscellaneous
ML	Milliliter
MM	Millimeter
MM3	Cubic Millimeter
MOCP	Maximum Overcurrent Protection
MOD	Motorized Operated Damper
MPS	Medium Pressure Steam Supply
MPT	Male Pipe Thread
MSD	Motorized Smoke Damper
MSFD	Motorized Smoke Fire Damper
MSIU	Mini Split Indoor Unit
MTD	Mounted
MU	Make Up
MUA	Make Up Air
MX	Metrix Utility Accounting System
MZ	Multi
NA	Not Applicable
NC	Normally Closed / Noise Criteria
NEG	Negative
NEMA	National Electrical Manufacturers Association
NFA	Net Free Area
NG	Natural Gas
NIC	Not In Contact
NK	Neck
NO	Normally Open
NO / #	Number
NOM	Nominal
NP	Non-potable Water
NPHP	Name Plate Horsepower
NPS	Nominal Pipe Size
NPSH	Net Positive Suction Head
NRD	Non
NRV	Non Return Valve
NTS	Not To Scale
O	Oxygen
OA	Outdoor Air
OAI	Outside Air Intake
OAP	Outside Air Percentage
OAT	Outdoor Air Temperature (in °f, Unless Otherwise Noted)
OBD	Opposed Blade Damper
OC	On Center
OD	Outdoor Diameter (in Inches, Unless Otherwise Noted)
ODP	Open Drip Proof
OED	Open End Duct
OF	Degrees Fahrenheit
OR	Oil Return
OS	Oil Supply
OV	Outlet Velocity
OWS	Operator Work Station
OZ.	Ounce
P	Pump
P/E	Pneumatic/electric
P/T	Pressure/temperature Port, Pete's Plug
PA	Pascal
PC	Performance Contracting
PCF	Pounds Per Cubic Foot
PCR	Pounds Per Cubic Foot
PD	Pressure Drop
PE	Professional Engineer
PF	Power Factor
PG	Pressure Gauge
PH	Phase
PHC	Pre-Heat coil
PICV	Pressure Independent Control Valve
PID	Proportional Integral Derivative
PL	Plate
PNEU	Pneumatic
PP	Primary Pump
PRD	Pressure Relief Damper
PREFAB	Prefabricated
PRES	Pressure
PRESS	Pressure
PROP	Propeller
PRV	Pressure Reducing Valve
PSF	Pounds Per Square Foot
PSI	Pounds Per Square Inch
PSIA	Pound Per Square Inch (Absolute)
PSID	Pounds Per Square Inch (Differential)
PSIG	Pound Per Square Inch (Gauge)
PTAC	Package Terminal Air Conditioning Unit
PUH	Propeller Unit Heater
PV	Plug Valve
PVC	Polyvinyl Chloride
QTY	Quantity
R	Radiant
R/E	Return And Exhaust
RA	Return Air
RAD	Radius
RAG	Return Air Grill
RAT	Return Air Temperature
RCD	Return Ceiling Diffuser
RCP	Radiant Ceiling Panel
RD	Roof Drain
RECOV	Recovery
RED	Reducer
REF	Reference
REQ'D	Required
REQD	Required
RET	Return
REV	Revision
RF	Return Fan
RFM	Refrigerant Monitor
RG	Return Air Grille
RH	Reheat
RHC	Reheat Coil
RL	Refrigerant Liquid
RLA	Rated Load Amperes
RLBG	Return Linear Bar Grille
RLF	Relief
RLSD	Return Linear Slot Diffuser
RM	Room
RPM	Revolutions Per Minute
RS	Refrigerant Suction
RTD	Resistance Temperature Detector
RTN	Return
RTU	Roof Top Air Handling Unit
RV	Relief Valve
RWO	Return Air Wall Opening (above Ceiling, Unless Otherwise Noted)
S	Sensor
SA	Supply Air (with A Unit Measurement Of Cfm)
SAD	Supply Air Duct
SAG	Supply Air Grill
SAT	Supply Air Temperature
SC	Shading Coefficient
SCD	Supply Ceiling Diffuser
SCH	Schedule
SCHED	Schedule
SCR	Screen
SCT	Saturated Condensing Temperature
SD	Smoke Damper
SDT	Saturated Discharge Temperature
SE	Smoke Exhaust
SEC	Seconds / Secondary
SED	See Electrical Drawings
SEER	Seasonal Energy Efficiency Ratio
SEER2	Seasonal Energy Efficiency Ratio 2
SEG	Smoke Extract Grille
SEN or SENS	Sensible
SENS	Sensible
SEP	Separate
SEQ	Sequence
SER	Series
SERV	Service
SF	Service Factor
SFD	Combination Smoke / Fire Damper
SHC	Sensible Heat Capacity
SHFG	Solar Heat Gain Factor
SHR	Sensible Heat Ratio
SHT	Sheet
SI	International Systems Of Units
SIM	Similar
SL	Linear Slot Diffuser
SLBG	Supply Linear Bar Grille
SLSD	Supply Linear Slot Diffuser
SM	Sheet Metal
SOL	Solenoid
SP	Secondary Pump
SPD	Stair Pressurization Duct
SPEC	Specification
SPF	Stair Pressurization Fan
SPLY	Supply
SQ	Square
SQFT	Square Feet
SS	Stainless Steel
SSH	Static Suction Head
SST	Saturated Suction Temperature
ST	Sound Trap
STD	Standard
STH	Static Total Head
STL	Steel
SUCT	Suction
SUP	Supply
SV	Service
SVH	Static Velocity Head
SW	Service Weight
SWP	Steam Working Pressure
SWS	Service Water
SX	Smoke Exhaust
T	Temperature (in °f, Unless Otherwise Noted)
TA	To Above
TAB	Testing, Adjusting, And Balancing
TB	To Below
TC	Temperature Control
TCC	Temperature Control Contractor
TCP	Temperature Control System Control Panel
TCS	Temperature Control System.
TD	Temperature Difference
TDH	Total Dynamic Head
TE	Toilet Exhaust
TED	Toilet Extract Duct
TEFC	Totally Enclosed Fan Cooled
TEMP	Temperature
TEV	Thermostatic Expansion Valve
TEWI	Total Equivalent Warming Impact
TF	Transfer Fan
TH	Thermometer
THK	Thick
TOD	Time Of Day
TON	12,000 BTUH (BTU per Hour) Cooling Capacity
TORR	Millimeter Of Mercury (mmhg)
TP	Total Pressure
TR	Temperature Rise (in °f, Unless Otherwise Stated)
TRD	Transfer Duct
TRG	Transfer Grille
TSP	Total Static Pressure
TSTAT	Thermostat
TX	Toilet Exhaust
TXV	Thermal Expansion Valve
TYP	Typical
UC	Undercut (door)
UF	Under Floor
UFAD	Underfloor Air Distribution
UH	Unit Heater
UON	Unless Otherwise noted
UV	Ultraviolet
V	Vent
VAC	Vacuum
VAR	Variable
VAV	Variable Air Volume
VB	Vacuum Breaker
VCD	Volume Control Damper
VCI	Vacuum Cleaning Inlet
VCL	Vacuum Cleaning Line
VD	Volume Damper
VEL	Velocity
VERT	Vertical
VF	Ventilation Fan
VFC	Variable Frequency Controller (or Vfd)
VFD	Variable Frequency Drive
VHP	Variable Refrigerant Volume Heat Pump Unit, For VRF Systems
VIB	Vibration
VIF	Verify In Field
VOL	Volume
VP	Velocity Pressure
VRC	Refrigerant System Controller, For VRF Systems
VRF or VRV	Variable Refrigerant Flow / Variable Refrigerant Volume
VSD	Variable Speed Drive
VSP	Variable Speed Pump(ing)
VTR	Vent Through Roof
VVD	Dual Inlet Variable Primary Air Volume Terminal Unit
VVF	Fan Powered Variable Primary Air Volume Terminal Unit
VVR	Variable Primary Air Volume Terminal Unit
VVT	Variable Volume Variable Temperature
W	Watt / Width / Wide
W/	With
W/O	Without
WB	Wet Bulb
WBT	Wet Bulb Temperature
WC	Water Column
WCO	Wall Clean Out
WCU	Water Chilling Unit
WFU	Water Filtration Unit
WG	Water Gauge
WH	Water Heater
WMS	Wire Mesh Screen
WO-SIZE	Wall-Opening Size
WPD	Water Pressure Drop
WR	Wall Register
WTD	Water Temperature Difference
YTD	Year To Date
ZV	Zone Valve

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Jim Dorsey

Writer and Reviewer at HeatingandCoolingUSA

Jim has 40 years of experience working in the residential and commercial HVAC Industry. He is certified in Environmental Control 1, Environmental Control 2, and Environmental Control 3- HVAC Heating and Industrial Electrical Service Certifications from the Society of Building Science Educators (SBSE) and holds a universal Refrigerant Training and Certification EPA card.