HVAC Abbreviations

• A - compressed air line or area
• ABC - above ceiling
• AC - air chamber, alternating current
• A/C - air conditioning
• AFF - above finished floor
• AFG - above finished grade
• AL - aluminum
• AMB - ambient
• AMP - ampere
• ARR - arrangement
• ATC - automatic temperature control, at ceiling
• ATM - atmosphere
• AUTO - automatic
• AUX - auxiliary
• AVG - average
• BBD - boiler blowdown
• BF - boiler feed
• BHP - boiler horsepower, brake horsepower
• BOD - bottom of duct
• BOP - bottom of pipe
• BOT - bottom
• BP - back pressure
• B & S - bell-and-spigot
• BSMT - basement
• BTU - British thermal unit
• BV - butterfly valve
• ^oC - degrees Celsius
• C - condensate line
• C to C - center to center
• CA - compressed air
• CAL - calorie
• CAP - capacity
• CD - condensate drain
• CF - chemical feed, cubic foot
• CFH - cubic feet per hour
• CFM - cubic feet per minute
• CI - cast iron
• CIRC - circular
• CL - center line
• CM - centimetre
• CM² - square centimetre
• CO - clean out
• COL - column
• CONC - concrete, concentric
• CONN - connect, connection
• CONT - continuation
• CPVC - chlorinated polyvinyl chloride
• CR - condenser return
• CRW - chemical resistant waste
• CS - condenser supply
• CTR - center
• CU - cubic
• CU FT. - cubic feet
• CU IN. - cubic inches
• CV - check valve
• CW - cold water
• CWR - cold water riser

• D - drain, deep
• DB - dry bulb
• DDC - direct digital control
• DEG - degree
• DELTAT - temperature difference
• DET - detail
• DIA - diameter
• DISC - disconnect
• DN - down
• DP - dew point temperature
• DR - drain
• DWG - drawing
• EA - exhaust air, each
• EAT - entering temperature
• EATR – Exhaust Air Transfer Ratio - to identify the amount of exhaust air transferred to inlet air in an energy recovery ventilator
• E to C - end to center
• EER - energy efficient ratio
• EFF - efficiency
• EJ - expansion joint
• EL - elevation
• ELB - elbow
• ELEC - electrical
• ENT - entering
• ERV – Energy Recovery Ventilator
• ESP - external static pressure
• ET - expansion tank
• EVAP - evaporator
• EWT - entering water temperature
• EXH - exhaust
• EXP - expansion
• EXST - existing
• EXT - external
• ^oF - degrees Fahrenheit
• F - Fahrenheit
• FC - flexible connector, flexible connection
• FCO - floor clean out
• FD - floor drain
• FDW - feed water
• FEC - fire extinguisher cabinet
• FF - finish floor
• FG - finish grade
• FHC - fire hose cabinet
• FLA - full load amps
• FLR - floor
• FM - flow meter
• FO - fuel oil
• FOV - flush out valve
• FPM - feet per minute
• FPS - feet per second
• FS - flow switch, federal specs
• FT - foot, feet
• FTG - fitting
• FU - fixture unit
• FV - flush valve

• G - gram, gas line
• GA - gauge
• GAL - gallons
• GALV - galvanized
• GL.V - globe valve
• GND - ground
• GPD - gallons per day
• GPH - gallons per hour
• GPM - gallons per minute
• GPS - gallons per second
• GR - grain
• GV - gate valve
• GWH - gas water heater
• H₂O - water
• HB - hose bibb
• HD - head
• Hg - mercury
• HGT - height
• HMD - humidity
• HORIZ - horizontal
• HP - horsepower
• HR - hour
• HRV – Heat Recovery Ventilator
• HTD - heated
• HTR - heater
• HW - hot water
• HWH - hot water heater
• HWR - hot water return, hot water riser
• HWS - hot water supply
• HWT - hot water tank
• HZ - herts
• ID - inside diameter
• IN. - inch
• INHg - inches of mercury
• INSUL - insulation
• INT - international
• INTL - internal
• IPS - iron pipe size
• IV - indirect vent
• IW - indirect waste
• J - joule
• K - kelvin
• KG - kilogram
• KM - kilometre
• KM² - square kilometre
• KPA - kilo pascal
• KS - kitchen sink
• KW - kilowatt
• L - length, liter
• LAT - leaving air temperature
• LB. - pound
• LBF - pound-force
• LIQ - liquid
• LP - low pressure
• LRA - locked rotor amps
• LVL - level
• LVR - louver
• LWT - leaving water temperature
• M - meter
• M² - square meter
• M TYPE - lightest type of rigid copper pipe
• MAN - manual
• MAT - mixed air temperature
• MAX - maximum
• MBH - thousand British thermal units per hour
• MFR - manufacturer
• MG - milligram
• MGD - millions gallons per day
• MIN - minimum or minute
• ML - milliliter
• MM - millimetre
• MM³ - cubic millimetre
• MPT - male pipe thread
• MTD - mounted
• MU - make up
• NA - not applicable
• NC - normally closed
• NEG - negative
• NIC - not in contact
• NO - normally open
• NPHP - name plate horsepower
• NPS - nominal pipe size
• NPSH - net positive suction head
• NTS - not to scale
• O - oxygen
• OA - outside air
• OAT - outside temperature
• OC - on center
• OD - outside diameter
• OED - open end duct
• OF - overflow
• OV - outlet velocity
• OZ. - ounce

• PA - pascal
• PC - plumbing contractor
• PCR - pumped condensate return
• PD - pressure drop
• PF - power factor
• PG - pressure gauge
• PL - plate
• PNEU - pneumatic
• PRESS - pressure
• PROP - propeller
• PRV - pressure reducing valve
• PSI - pounds per square inch
• PSIA - pound per square inch absolute
• PSIG - pound per square inch gauge
• PV - plug valve
• QTY - quantity
• RA - return air
• RAD - radius
• RAT - return air temperature
• RD - roof drain
• R/E - return and exhaust
• RECOV - recovery
• RED - reducer
• REF - reference
• RH - relative humidity
• REQD - required
• REV - revision
• RL - refrigerant liquid
• RLA - Rated Load Amperes
• RM - room
• RS - refrigerant suction
• RTN - return
• RV - relief valve
• S - switch
• SA - shock absorber, supply air
• SAT - supply air temperature
• SCH - schedule
• SDT - saturated discharge temperature
• SEC - seconds, secondary
• SENS - sensible
• SEP - separate
• SEQ - sequence
• SER - series
• SERV - service
• SF - service factor
• SHT - sheet
• SI - international systems of units
• SOL - solenoid
• SP - static pressure
• SPEC - specification
• SQ. - square
• SQ.FT. - square feet
• SS - stainless steel
• SSH - static suction head
• SST - saturated suction temperature
• STD - standard
• STH - static total head
• STL - steel
• SUCT - suction
• SPLY - supply
• SV - service
• SVH - static velocity head
• SW - service weight
• SWS - service water
• TD - temperature difference
• TDH - total dynamic head
• TEMP - temperature
• TH - thermometer
• THK - thick
• TP - total pressure
• TSP - total static pressure
• UF - under floor
• UH - unit heater
• V - vent, volt, volume
• VAC - vacuum
• VAV - variable air volume
• VB - vacuum breaker
• VCI - vacuum cleaning inlet
• VCL - vacuum cleaning line
• VEL - velocity
• VERT - vertical
• VIB - vibration
• VOL - volume
• VSD - variable speed drive
• VP - velocity pressure
• VTR - vent thru roof
• W - watt, width, wide
• WB - wet bulb
• WCO - wall clean out
• WG - water gauge
• WH - water heater

Temperature ^oC
K
^oF

Length m
km
in
ft
yards
miles
naut miles

Area m²
km²
in²
ft²
miles²
acres

Volume m³
liters
in³
ft³
us gal

Weight kg_f
N
lbf

Velocity m/s
km/h
ft/min
ft/s
mph
knots

Pressure Pa
bar
mm H₂O
kg/cm²
psi
inches H₂O

Flow m³/s
m³/h
US gpm
cfm