HVAC Acronyms & HVAC Terms

This is a comprehensive list of HVAC Acronyms and HVAC Terms. High Performance HVAC is certain there are more terms and acronyms.

• 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

1. B - Boiler
2. BACnet - Computer communication protocol for building automation systems and control networks
3. BAS - Building Automation System
4. BI - Binary Input
5. BMS - Building Management System
6. BO - Binary Output
7. BP - Backflow Preventer
8. BTU - British Thermal Unit
9. BTUh - Brtish Thermal Units per Hour

• 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

1. DA - Discharge Air or Direct Acting
2. DAT - Discharge Air Temperature
3. DB - Dry Bulb or Dead Band
4. DC - Direct Current
5. DCBP - Double Check Backflow Preventer
6. DD - Degree Day
7. DDC - Direct Digital Control
8. DI - Digital Input
9. DO - Digital Output
10. DP - Differential Pressure
11. DPDT - Double Pole Double Throw
12. DPST - Double Pole Single Throw
13. DSI - Direct Spark ignition
14. 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 Pnuematic
• ERV - Energy Recovery Ventilator
• EXV - Electronic Expansion Valve

1. FA - Fire Alarm
2. FAI - Fresh Air Intake
3. FCU - Fan Coil Unit
4. FD - Fire Damper
5. FLA - Full Load Amps
6. FPM - Feet Per Minute
7. FPVAV - Fan Powered Variable Air Volume Box
8. FS - Float Switch
9. F & T - Float & Thermostatic

• GPM - Gallons per Minute
• GWP - Global Warming Potential

1. HEPA - High Efficiency Particulate Arresting
2. HCFC - HydroChloroFluoroCarbon
3. HD - Hot Deck
4. HFC - HydroFluoroCarbon
5. HOA - Hand Off Auto
6. HP - High Pressure or Horse Power
7. HPS - High Pressure Steam
8. HRU - Heat Recovery Unit
9. HRV - Heat Recovery Ventilator
10. HSI - Hot Surface Ignition
11. HSPF - Heating Seasonal Performance Factor
12. HSTAT - Humidistat
13. HVAC - Heating, Ventilation, & Air Conditioning
14. HVAC&R - Heating, Ventilation, Air Conditioning, & Refrigeration
15. HWP - Hot Water Pump
16. 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)
17. 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)
18. HWUH - Hot Water Unit Heater
19. HX - Heat Exchanger
20. 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

1. KO - Knock Out
2. KW - Kilowatts

• LL - Low Limit
• LP - Low Pressure or Liquified Petroleum
• LPS - Low Pressure Steam
• LRA - Locked Rotor Amps
• LWCO - Low Water Cut Off

1. MA - Mixed Air
2. MAT - Mixed Air Temperature
3. MAU - Make-up Air Unit
4. MCC - Motor Control Center
5. MFD - Micro-Farad
6. MP - Motor Protector
7. MPT - Male Pipe Thread
8. MUW - Make-up Water
9. 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

1. OA - Outside Air
2. OAT - Outside Air Temperature
3. OP - Oil Pressure
4. ODP - Ozone Depletion Potential

• PCB - Printed Circuit Board
• PE - Pnuematic 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

1. RA - Return Air or Reverse Acting
2. RAT - Return Air Temperature
3. RF - Return Fan
4. RH - Relative Humidity
5. RPBP - Reduced Pressure Backflow Preventer (sometimes also seen as RPZ)
6. RPM - Revolutions Per Minute
7. RTU - Roof Top Unit
8. 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 Set Point
• SPDT - Single Pole Double Throw
• SPST - Single Pole Single Throw
• SV - Solenoid Valve

1. TD - Temperature Difference or Time Delay
2. TDS - Total Dissolved Solids
3. TH - Thermometer in a Thermowell
4. TEV - Thermostatic Expansion Valve (sometimes also seen as TXV)
5. Ton - ton of refrigeration effect
6. TSTAT - Thermostat

• UH - Unit Heater
• UMC - Uniform Mechanical Code
• UV - Ultra-Violet or Unit Ventilator

1. VAV - Variable Air Volume
2. VFD - Variable Frequency Drive
3. VSD - Variable Speed Drive
4. VVT - Variable Volume/Temperature

• W - Watt
• WB - Wet Bulb
• WC - Water Column

          XFMR - Transformer

          ZD - Zone Damper