HVAC/R Glossary

This glossary of HVAC and Refrigeration related abbreviations can help you navigate the most common terms you'll come across during your buying decision.

Acronym	What it stands for …
A		Back to Top
AC	Air Conditioning
AC	Alternating Current
ACH	Air Changes per Hour
ACM	Asbestos Containing Material
AEE	Association of Energy Engineers
AFD	Adjustable Frequency Drive
AFUE	Annual Fuel Efficiency Ratio
AHU	Air Handling Unit
AI	Analog Input
Anti-Ice Control	same as a freeze stat or encapsulated pressure control
AO	Analog Output
Aquastat	controls the use of a water system. We sell the Honeywell aquastats. You can also use the Ranco ETC series of temp controls.
ASHRAE	American Society of Heating Refrigeration and Air Conditioning Engineers
B		Back to Top
B	Boiler
BACnet	A Data Communication Protocol for Building Automation and Control Networks
BAS	Building Automation System
Bazooka	636 concentric vent kit
BCA	Building Commissioning Association
Bearshit	cork tape
BI	Backward Incline
BI	Binary Input
BO	Binary Output
BSLN	Baseline
BTU	British Thermal Unit
BTUH	Brtish Thermal Units / Hour
BY	Base Year
C		Back to Top
Can	a small hermetic compressor
CAV	Constant Air Volume
CD	Cold Deck
CDD	Cooling Degree Days
CEM	Certified Energy Manager
CFC	ChloroFluoroCarbon
CFM	Cubic Feet per Minute
CH	Chiller
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
CLF	Cooling Load Factor
CLTD	Cooling Load Temperature Difference
COP	Coefficient Of Performance
CRAC	Computer Room Air Conditioner
CT	Cooling Tower
CV	Constant Volume
CVRMSE	Coefficient of Variation of the Root Mean Square of the Error
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		Back to Top
DA	Discharge Air
DB	Data Base
DB	Dry Bulb
DC	Direct Current
DCV	Demand Controlled Ventilation
DD	Degree Day
DDC	Direct Digital Control
DH	Duct Heater
DI	Digital Input
DO	Digital Output
DP	Dew Point
DP	Differential Pressure
DX	Direct Expansion
E		Back to Top
EAT	Entering Air Temperature
ECM	Electronically Commutated Motor
ECM	Energy Conservation Measure
ECO	Energy Conservation Opportunity
EDH	Electric Duct Heater
EEM	Energy Efficiency Measure
EER	Energy Efficiency Ratio
EF	Exhaust Fan
Eggcrate	this is a plastic grill material that can replace ceiling tiles. Part Number: 2-4-1/2-ALL
EH	Electric Heater
EMS	Energy Management System
ESCO	Energy Service Company
EUH	Electric Unit Heater
EWT	Entering Water Temperature
F		Back to Top
FC	Forward Curve
FCU	Fan Coil Unit
FIM	Facility Improvement Measure
Firecracker	Fan cycling control
FLA	Full Load Amps
Flux	Used to etch metal for filler (solder) to bold
FMS	Facility Management System
FPM	Feet Per Minute
Freeze-Stat	a switch to stop evaporators from icing up. (eg. AE1C-1-ECO or HH)
FW	Feed Water
G		Back to Top
GPM	Gallons Per Minute
GUI	Graphical User Interface
H		Back to Top
HCFC	Hydrochlorocfuorocarbon
HD	Hot Deck
HDD	Heating Degree Days
HEPA	High Efficiency Particulate Arresting
HFC	HydroFluoroCarbon
HHV	Higher Heating Value
HHWP	Heating Hot Water Pump
HHWR	Heating Hot Water Return
HHWS	Heating Hot Water Supply
HL	High Limit
HPS	High Pressure Steam
HR	Heat Recovery
HRU	Heat Recovery Unit
HRV	Heat Recovery Ventilator
HSPF	Heating Seasonal Performance Factor
HVAC	Heating Ventilation and Air Conditioning
HWP	Hot Water Pump
HWR	Hot Water Return
HWS	Hot Water Supply
HWRT	Hot Water Return Temperature
HWST	Hot Water Supply Temperature
HX	Heat Exchanger
I		Back to Top
I/O	Input Output
Inducer Motor	also known as a venter motor. It vents harmful gas out of the furnace through 636 pipe to the outside of the house or building
IAQ	Indoor Air Quality
IPMVP	International Performance Measurement and Verification Protocol
IR	Infra-Red
J		Back to Top
Jellybean	specific style of crimp connector
K		Back to Top
King Valve	The shut off valve on a condensing unit. This where refrigerant is charged and where the line set piping connects to
L		Back to Top
LAT	Leaving Air Temperature
LHV	Lower Heating Value
Line Voltage Thermostat	Used for electrical baseboards or anything using 120/208v to match amperage. Look for these Honeywell items
LL	Low Limit
LON	Local Operating Network
LP	Low Pressure
LPS	Low Pressure Steam
LRA	Locked Rotor Amps
LWBT	Leaving Wet Bulb Temperature
LWT	Leaving Water Temperature
M		Back to Top
M&V	Measurement and Verification
MA	Mixed Air
MAT	Mixed Air Temperature
MCC	Motor Control Center
MUA	Make-up Air Unit
Muffin Motor	3.3" unit bearing motor eg. R-5411
MX	Metrix Utility Accounting System
MZ	Multi-Zone
N		Back to Top
NC	Normally Closed
NEMA	National Electrical Manufacturers Association
NO	Normally Open
NPSH	Net Positive Suction Head
O		Back to Top
OA	Outside Air
OAP	Outside Air Percentage
OAT	Outside Air Temperature
OCS	this stands for “Our Compressor Shop”. It is referring to internal purchases used for the business. It was called this when RSL operated their own compressor rebuild shop decades ago
ODP	Open Drip Proof
OWS	Operator Work Station
P		Back to Top
Pancake	636 low profile vent termination kit (1HT
Pancake Drier	stout suction line filter driers. ie C-145-S-TT-HH
PC	Performance Contracting
PE	Professional Engineer
Penthouse Unit	they are likely referring to a self-contained refrigeration system that is mounted on the top of a walk-in box. We stock the Bohn Pro3
PH	Pre-Heat
PID	Proportional Integral Derivative
PRV	Pressure Relief Valve
PRV	Pressure Reducing Valve
PTAC	Packaged Terminal Air Conditioner
Q		Back to Top
R		Back to Top
RA	Return Air
Rezpack/Respack	this is short for “Residential Packaged Unit”. They are a rooftop square in shape that are typically 2-5 tons. In some parts of North America they are used in residential applications.
RF	Return Fan
RH	Reheat
RH	Relative Humidity
RPM	Revolutions Per Minute
RTD	Resistance Temperature Detector
RTU	Roof Top Unit
S		Back to Top
SA	Supply Air
SAT	Supply Air Temperature
SC	Shading Coefficient
SEER	Seasonal Energy Efficiency Ratio
SF	Supply Fan
SHFG	Solar Heat Gain Factor
SHR	Sensible Heat Ratio
Silfos	comes in 5 and 15% silver and is used to bond copper to copper. No flux required
Silver Solder	Silver solder required flux or comes pre fluxed and is used for bonding dissimilar metals
Skeleton Motor	specific style of motor used in small refrigeration applications.
SP	Set Point
SP	Static Pressure
Super Hose	Also known as High Pressure Control Hose. We stock the Ritchie yellow jacket product. Part #: 78712, 78718, 78724, 78730, 78736, 78748, 78760, 78772
SWP	Steam Working Pressure
T		Back to Top
T	Temperature
T	Thermostat
TEV	Thermostatic Expansion Valve
TOD	Time Of Day
TORR	Millimeter of Mercury (mmHg)
Trax/Traxx Oil/Traxx Oil Control	Trax is an old brand name. The customer is likely looking for a Copeland oil level control – Part #: OMB-JB1
TXV	Thermostatic Expansion Valve
U		Back to Top
UH	Unit Heater
UV	UltraViolet
UV	Unit Ventilator
V		Back to Top
VAV	Variable Air Volume
VD	Volume Damper
Venter Motor	also known as an inducer motor. It vents harmful gas out of the furnace through pipes to the outside of the house or building
VFD	Variable Frequency Drive
VSD	Variable Speed Drive
VSP	Variable Speed Pump(ing)
W		Back to Top
WB	Wet Bulb
WC	Water Column
Window Shaker	refers to the window mounted air conditioners. We stock Friedrich, and have access to Comfort-aire and Amana
X		Back to Top
Y		Back to Top
YTD	Year To Date
Z		Back to Top

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