A/D

Analog to Digital

AC

Air Conditioning - Alternating current

ACH

Air Changes per Hour

ACM

Asbestos Containing Material

ADC

Analog to Digital Converter

AFUE

Annual Fuel Efficiency Ratio

AHU

Air Handling Unit

AI

Analog Input

AL

Air Leakage

AO

Analog Output

ASC

Application Specific Controller

ATC

Automatic Temperature Control

AVB

Atmospheric Vacuum Breaker

AWG

American Wire Gage

C

Chiller

CA

Central Air

CAV

Constant Air Volume

CB

Circuit Breaker

CCH

CrankCase Heater

CD

Cold Deck

CDD

Cooling Degree Days

CFC

ChloroFluoroCarbon

CFM

Cubic Feet per Minute

CFU

Colony Forming Units

CHWP

Chilled Water Pump

CHWR

Chilled Water Return

CHWS

Chilled Water Supply

CI

Cast Iron

CLF

Cooling Load Factor

CLTD

Cooling Load Temperature Difference

COP

Coefficient Of Performance

COS

Change Of State

COV

Change Of Value

CPR

Crankcase Pressure Regulating

CPVC

Chlorinated PolyVinyl Chloride

CRAC

Computer Room Air Conditioner

CSA

Canadian Standards Association

CSIR

Capacitor Start Induction Run

CSR

Capacitor Start Capacitor Run

CT

Cooling Tower - Current Transducer

CTH

Constant Temperature and Humidity

CUH

Cabinet Unit Heater

CV

Constant Volume - Control Valve

CHWP

Chilled Water Pump

Condenser Water Pump

CHWR

Chilled Water Return

Condenser Water Return

CHWS

Chilled Water Supply

Condenser Water Supply

D/A

Digital to Analog

DA

DeAerator - Direct Acting - Discharge Air

DAC

Digital to Analog Conversion

DB

Data Base - Dry Bulb

DC

Duty Cycle

DCBP

Double Check Back flow Preventer

DCDA

Double Check Detector Assembly

DCS

Distributed Control System

DD

Degree Day - Direct Drive

DDC

Direct Digital Control

DH

Duct Heater

DI

Digital Input

DL

Demand Limit

DMM

Digital Multi Meter

DO

Digital Output

DP

Dew Point - Differential Pressure

DPDT

Double Pole Double Throw

DPST

Double Pole Single Throw

DSI

Direct Spark Ignition

DCV

Demand Controlled Ventilation

DVM

Digital Volt Meter

DW

Distilled Water

DX

Direct eXpansion

EAT

Entering Air Temperature

EDR

Equivalent Direct Radiation

EER

Energy Efficiency Ratio

EEV

Electronic Expansion Valve

EMF

ElectroMotive Force

EWT

Entering Water Temperature

EDH

Electric Duct Heater

EF

Exhaust Fan

EH

Electric Heater

EMS

Energy Management System

EOL

End Of Line

EP

Electric to Pressure or Electric to Pneumatic

EPR

Evaporator Pressure Regulator

EPT

Electric to Pressure Transducer

ERV

Energy Recovery Ventilator

ESO

Enthalpy Switch Over

EUH

Electric Unit Heater

EWC

Electric Water Cooler

EXV

Electronic Expansion Valve

F

Fuse

FA

Fire Alarm

FC

Forward Curve

FCU

Fan Coil Unit

FD

Fire Damper

FLA

Full Load Amps

FMS

Facility Management System

FP

Full Port

FPM

Feet Per Minute

FPT

Female Pipe Thread

FS

Float Switch - Flow Switch

FV

Face Velocity

F&T

Float & Thermostatic

FTU

Fan Terminal Unit

FW

Feed Water

G

Gas

GE

Grooved End

GI

Galvanized Iron

GPM

Gallons Per Minute

GUI

Graphical User Interface

GWP

Global Warming Potential

HEPA

High Efficiency Particulate Arresting

HCFC

Hydrochlorocfuorocarbon

HD

Hot Deck

HDD

Heating Degree Days or Hard Disk Drive

HFC

HydroFluoroCarbon

HGB

Hot Gas Bypass

HHV

Higher Heating Value

HHWP

Heating Hot Water Pump

HHWR

Heating Hot Water Return

HHWS

Heating Hot Water Supply

HI

Hydronics Institute

HL

Head Loss

HL

High Limit

HOA

Hand Off Auto

HP

High Pressure

HPS

High Pressure Steam

HR

Heat Recovery

HRU

Heat Recovery Unit

HRV

Heat Recovery Ventilator

HSI

Hot Surface Igniter

HSPF

Heating Seasonal Performance Factor

HVAC

Heating Ventilation and Air Conditioning

HWG

Hot Water Generator

HWP

Hot Water Pump

HWR

Hot Water Return

HWS

Hot Water Supply

HX

Heat eXchanger

I/O

Input Output

IA

Intellegent Automation

IAQ

Indoor Air Quality

IM

Ice Maker

IP

Iron Pipe

IPS

Iron Pipe Size

IR

InfraRed

JB

Junction Box

JIC

Joint Industries Council

K

Relay

KO

Knock Out

LAT

Leaving Air Temperature

LHV

Lower Heating Value

LL

Low Limit

LMTD

Log Mean Temperature Difference

LOC

Loss Of Charge

LP

Liquefied Petroleum - Low Pressure

LPS

Low Pressure Steam

LR

Load Rolling - Long Radius

LRA

Locked Rotor Amps

LS

Level Switch

LWBT

Leaving Wet Bulb Temperature

LWCO

Low Water Cut Off

LWT

Leaving Water Temperature

MUA

Make-up Air Unit

MAWP

Maximum Allowable Working Pressure

MCC

Motor Control Center

MFD

Micro Farad

MI

Malleable Iron

MMI

Man Machine Interface

MODEM

Modulator Demodulator

MOP

Maximum Operating Pressure

MOV

Motor Operated Valve

MP

Motor Protector

MPT

Male Pipe Thread

MPY

Mils Per Year

MRA

Message Requiring Acknowledgment

MTD

Month To Date

MVAC

Motor Vehicle Air Conditioning

MZ

Multiple Zone

NEC

National Electrical Code

NC

Noise Criteria or Normally Closed

NEMA

National Electrical Manufacturers Association

NO

Normally Open

NPSH

Net Positive Suction Head

NPT

National Pipe Thread or National Pipe Taper

NTC

Negative Temperature Coefficient

NTU

Number of Transfer Units

ODA / OSA / OAT

Outdoor Air / Outside Air / Outside Air Temperature

OBD

Opposed Blade Damper

ODP

Open Drip Proof

ODS

Ozone Depleting Substances

OP

Oil Pressure

OPS

Oil Pressure Switch

ORT

Optimum Run Time

OSS

Optimum Start/Stop Time

OWS

Operator Work Station

PB

Proportional Band

PCB

Printed Circuit Board

PBD

Parallel Blade Damper

PE

Plain End or Pressure to Electric or Pneumatic to Electric

PET

Pressure to Electric Transducer

PEX

cross-linked PolyEthylene

PFC

PerFluoroCarbon

PH

PreHeat

PID

Proportional Integral Derivative

P&ID

Piping & Instrumentation Drawing

POT

Portable Operators Terminal

PRV

Pressure Reducing Valve - Pressure Relief Valve

PS

Pressure Switch

PSC

Permanent Split Capacitor

PT

Pressure Temperature

PTAC

Packaged Terminal Air Conditioner

PTC

Positive Temperature Coefficient

PVB

Pressure Vacuum Breaker

PVC

PolyVinyl Chloride

PWM

Pulse Width Modulation

QO

Quick Opening

R

Return

RA

Return Air

Reverse Acting

RAG

Return Air Grille

RF

Radio Frequency

Return Fan

RH

ReHeat

Relative Humidity

RMS

Root Mean Square

RP

Reduced Port

RPBP

Reduced Pressure Back flow Preventer

RPDA

Reduced Pressure Detector Assembly

RPM

Revolutions Per Minute

RTD

Resistance Temperature Detector

RV

Reversing Valve

S

Supply

SA / SAT

Supply Air / Supply Air Temperature

SAE

Society of Automotive Engineers

SAV

Solenoid Air Valve

SC

Shading Coefficient

SCFM

Standard Cubic Feet per Minute

SCIM

Standard Cubic Inches per Minute

SD

Smoke Damper

SE

Shaft End

SEER

Seasonal Energy Efficiency Ratio

SEHVAC

Sci.Engr.Heat-Vent-AC

SF

Service Factor - Supply Fan

SH

SuperHeat

SHFG

Solar Heat Gain Factor

SHR

Sensible Heat Ratio

SI

Single Inlet

SP

Static Pressure - Setpoint

SPDT

Single Pole Double Throw

SPL

Sound Power Level

SPST

Single Pole Single Throw

SR

Short Radius - Sound Rating

SS

Solid State - Stainless Steel

SUS

Saybolt Universal Seconds

SV

Solenoid Valve

SWP

Steam Working Pressure

T

Temperature

T&C

Threaded and Coupled

TB

Terminal Block

TCT

Temperature Control Tubing

TD

Temperature Difference - Time Delay

TDC

Time Delay Closed

TDO

Time Delay Open

TDS

Total Dissolved Solids

TDV

Triple Duty Valve

TE

Temperature Element

TEFC

Totally Enclosed Fan Cooled

TEV

Thermostatic Expansion Valve

TH

Total Hardness

TOD

Time Of Day

TP

Total Pressure - Twisted Pair

TR

Throttling Range

TS

Temperature Switch

TUC

Terminal Unit Controller

TXV

Thermostatic expansion Valve

UD

Upload Download

UH

Unit Heater

UTP

UnTwisted Pair

UV

UltraViolet - Unit Ventilator

VAV

Variable Air Volume

VD

Volume Damper

VE

Value Engineering

VFD

Variable Frequency Drive

VOM

Volt Ohm Meter

VP

Velocity Pressure

VSP

Variable Speed Pump(ing)

V V T

Variable Volume Variable Temperature

V W V

Variable Water Volume

WB

Wet Bulb

WC

Water Column

WOG

Water Oil Gas

WP

Working Pressure

X

By

XFMR

Transformer

Y

Wye

YTD

Year To Date

ZD

Zone Damper

ZOH

Zero Order Hold