HVAC Definitions Terms & Acronyms | Heating Cooling - This is a comprehensive list of HVAC Definitions Terms & Acronyms. High Performance HVAC is certain there are more terms and acronyms. If you know of something we missed please email us. Thanks!

HVAC Definitions Terms & Acronyms

VSD or Variable Speed Drives

AC – Air Conditioning or Alternating Current

ACCA – Air Conditioning Contractors Associations

AFUE – Annual Fuel Utilization Efficiency

AHU – Air Handling Unit

AI – Analog Input

AMCA – Air Movement and Control Association

AO – Analog Output

AQS – Air Quality Systems

ASHRAE – American Society of Heating, Refrigerating, and Air Conditioning Engineers

AV – Automatic Air Vent

AWG – American Wire Gage

B – Boiler

BACnet – Computer communication protocol for building automation systems and control networks

BAS – Building Automation System

BI – Binary Input

BMS – Building Management System

BO – Binary Output

BP – Backflow Preventer

BTU – British Thermal Unit

BTUh – Brtish Thermal Units per Hour

HVAC Definitions Terms & Acronyms

CAV – Constant Air Volume

CD – Cold Deck (also Condensation Drain)

CFC – ChloroFluoroCarbon

CFM – Cubic Feet per Minute

CHR – Chilled Water Return (can also have an S in front of the acronym which stands for Secondary when secondary water loops have secondary loops)

CHS – Chilled Water Supply (can also have an S in front of the acronym which stands for Secondary when secondary water loops have secondary loops)

CHWP – Chilled Water Pump (can also have an S in front of the acronym which stands for Secondary when secondary water loops have secondary loops)

CHWR – Chilled Water Return (can also have an S in front of the acronym which stands for Secondary when secondary water loops have secondary loops)

CHWS – Chilled Water Supply (can also have an S in front of the acronym which stands for Secondary when secondary water loops have secondary loops)

CO – Clean Out (also Carbon Monoxide)

COP – Coefficienct of Performance

CRAC – Computer Room Air Conditioner

CRAH – Computer Room Air Handler

CSR – Capacitor Start Capacitor Run

CV – Constant Volume

CWP – Condenser Water Pump

CWR – Condenser Water Return

CWS – Condenser Water Supply

HVAC Definitions Terms & Acronyms

DA – Discharge Air or Direct Acting

DAT – Discharge Air Temperature

DB – Dry Bulb or Dead Band

DC – Direct Current

DCBP – Double Check Backflow Preventer

DD – Degree Day

DDC – Direct Digital Control

DI – Digital Input

DO – Digital Output

DP – Differential Pressure

DPDT – Double Pole Double Throw

DPST – Double Pole Single Throw

DSI – Direct Spark ignition

DX – Direct Expansion

EDR – Equivalent Direct Radiation

EER – Energy Efficiency Ratio

EMF – Electromotive Force

EF – Exhaust Fan

EMCS – Energy Management Control System

EMS – Energy Management System

EP – Electric to Pneumatic

ERV – Energy Recovery Ventilator

EXV – Electronic Expansion Valve

FA – Fire Alarm

FAI – Fresh Air Intake

FCU – Fan Coil Unit

FD – Fire Damper

FLA – Full Load Amps

FPM – Feet Per Minute

FPVAV – Fan Powered Variable Air Volume Box

FS – Float Switch

F & T – Float & Thermostatic

HVAC Definitions Terms & Acronyms

GPM – Gallons per Minute

GWP – Global Warming Potential

HEPA – High-Efficiency Particulate Arresting

HCFC – HydroChloroFluoroCarbon

HD – Hot Deck

HFC – HydroFluoroCarbon

HOA – Hand Off Auto

HP – High Pressure or Horse Power

HPS – High-Pressure Steam

HRU – Heat Recovery Unit

HRV – Heat Recovery Ventilator

HSI – Hot Surface Ignition

HSPF – Heating Seasonal Performance Factor

HSTAT – Humidistat

HVAC – Heating, Ventilation, & Air Conditioning

HVAC&R – Heating, Ventilation, Air Conditioning, & Refrigeration

HWP – Hot Water Pump

HWR – Hot Water Return (can also have an S in front of the acronym which stands for Secondary when hot water loops have secondary loops)

HWS – Hot Water Supply (can also have an S in front of the acronym which stands for Secondary when hot water loops have secondary loops)

HWUH – Hot Water Unit Heater

HX – Heat Exchanger

HZ – Hertz
I/O – Input/Output

IAQ – Indoor Air Quality

IMC – International Mechanical Code

in. Hg – inches of mercury vacuum

in. WC – inches of Water Column

IRH – Infrared Heater

JB – Junction Box

KO – Knock Out

KW – Kilowatts

HVAC Definitions Terms & Acronyms

LL – Low Limit

LP – Low Pressure or Liquified Petroleum

LPS – Low-Pressure Steam

LRA – Locked Rotor Amps

LWCO – Low Water Cut Off

MA – Mixed Air

MAT – Mixed Air Temperature

MAU – Makeup Air Unit

MCC – Motor Control Center

MFD – Micro-Farad

MP – Motor Protector

MPT – Male Pipe Thread

MUW – Make-up Water

MV – Manual Air Vent

NC – Normally Closed

NEC – National Electric Code

NFPA – National Fire Protection Association

NO – Normally Open

NPT – National Pipe Thread

NTC – Negative Temperature Coefficient

OA – Outside Air

OAT – Outside Air Temperature

OP – Oil Pressure

ODP – Ozone Depletion Potential

PCB – Printed Circuit Board

PE – Pneumatic to Electric

PID – Proportional, Integral, & Derivative

PRV – Pressure Reducing Valve

PSC – Permanent Split Capacitor

PSIA – Pounds per Square Inch Absolute

PSIG – Pounds per Square Inch Gauge

PT – Pressure Temperature

PTAC – Portable Terminal Air Conditioner

PTC – Positive Temperature Coefficient

PWM – Pulse Width Modulation

HVAC Definitions Terms & Acronyms

RA – Return Air or Reverse Acting

RAT – Return Air Temperature

RF – Return Fan

RH – Relative Humidity

RPBP – Reduced Pressure Backflow Preventer (sometimes also seen as RPZ)

RPM – Revolutions Per Minute

RTU – Roof Top Unit

RV – Reversing Valve

SA – Supply Air

SAT – Supply Air Temperature

SCADA – Supervisory Control and Data Acquisition

SD – Smoke Damper

SEER – Seasonal Energy Efficiency Ratio

SF – Service Factor or Supply Fan

SH – Super Heat

SMACNA – Sheet Metal and Air Conditioning Contractors National Association

SP – Static Pressure or SetPoint

SPDT – Single Pole Double Throw

SPST – Single Pole Single Throw

SV – Solenoid Valve

TD – Temperature Difference or Time Delay

TDS – Total Dissolved Solids

TH – Thermometer in a Thermowell

TEV – Thermostatic Expansion Valve (sometimes also seen as TXV)

Ton – a ton of refrigeration effect

TSTAT – Thermostat

UH – Unit Heater

UMC – Uniform Mechanical Code

UV – Ultra-Violet or Unit Ventilator

VAV – Variable Air Volume

VFD – Variable Frequency Drive

VSD – Variable Speed Drive

VVT – Variable Volume/Temperature

W – Watt

WB – Wet Bulb

WC – Water Column

XFMR – Transformer

ZD – Zone Damper

HVAC Definitions Terms & Acronyms

Technical Resource: Refrigeration and Air Conditioning Technology