2,400+ Definitions
HVAC GLOSSARY
Every HVAC term, acronym, and industry phrase — defined in plain English.
Contact Factor
The complement of bypass factor, representing the fraction of air…
Contact Weld
A failure condition in which the main contacts of a…
Contactor
A contactor is an electromagnetic switching device that controls power…
Contactor Arc Chute
A set of metal plates or other arc-extinguishing materials mounted…
Contactor Auxiliary Contact
A supplementary low-current contact block mechanically linked to a contactor’s…
Contactor Failure
Contactor failure occurs when the electromagnetic switch fails to close…
Contaminant Source Control
The practice of eliminating or reducing indoor air pollutant sources…
Continuity Test
A continuity test measures whether electrical current can flow unobstructed…
Continuous Commissioning
Continuous commissioning is the sustained verification and optimization of building…
Continuous Insulation
Continuous insulation is a thermal barrier applied across the entire…
Continuous Monitoring
Continuous monitoring refers to real-time, 24/7 measurement of indoor air…
Control Board
A control board is the central electronic component that manages…
Control Calibration
Control calibration involves adjusting thermostat and building management system settings…
Control Damper
A control damper is an automatic or modulating damper controlled…
Control Diagram
A Control Diagram is a detailed schematic illustrating all sensors,…
Control Loop
A closed feedback system consisting of a sensor, controller, and…
Control Narrative
A Control Narrative is a written description of how a…
Control Point
The actual value of the controlled variable at which a…
Control System Design
Control System Design specifies the hardware, software, and logic sequences…
Control Transformer
A control transformer is a step-down transformer that reduces line…
Control Valve
A Control Valve is an actuated device that modulates fluid…
Controlled Environment
A controlled environment is a space where temperature, humidity, air…
Convection
Convection is the transfer of thermal energy through the movement…
Convector
A convector is a heating device that transfers warmth from…
Converging Tee
A duct fitting in which two airstreams merge into a…
Cool Roof
A cool roof is a roofing system with high solar…
Cooling Coil
A cooling coil is a heat exchanger that removes thermal…
Cooling Degree Hours
The sum of hourly differences between outdoor dry-bulb temperature and…
Cooling Load
Cooling load is the rate at which heat must be…
Cooling Load Calculation
Cooling load calculation determines the total heat removal capacity (in…
Cooling Load Temperature Difference
A tabulated equivalent temperature difference used with the U-factor of…
Cooling Seasonal Performance Factor
Cooling Seasonal Performance Factor (CSPF) measures the total cooling output…
Cooling Tower
A cooling tower is a heat rejection device that transfers…
Cooling Tower Blowdown
Blowdown is the controlled release of concentrated circulating water from…
Cooling Tower Chemical Treatment
Cooling tower chemical treatment involves adding specialized biocides, corrosion inhibitors,…
Cooling Tower Efficiency
Cooling tower efficiency measures how effectively a tower removes heat…
Cooling Tower Fan Control
The modulation of cooling tower fan speed or staging to…
Cooling Tower Makeup Water
Makeup water is fresh water added to the cooling tower…
COP
COP (Coefficient of Performance) measures the ratio of heat output…
COP (Coefficient of Performance)
Coefficient of Performance (COP) measures the efficiency of a heat…
Copper Pipe
Copper pipe is a rigid or semi-rigid tubing made from…
Core Depressor Tool
A specialized valve stem wrench or fitting adapter used to…
Counter Flow Heat Exchanger
A counter flow heat exchanger operates with fluids moving in…
Counterflow Tower
A counterflow cooling tower directs air vertically upward while water…
CPVC Pipe
CPVC (chlorinated polyvinyl chloride) pipe is a rigid plastic tubing…
CRAC Unit
A Computer Room Air Conditioner (CRAC) unit is a close-control…
Crankcase Heater
A crankcase heater is a small electrical resistance heating element…
Crawl Space Encapsulation
Crawl space encapsulation is the process of sealing and conditioning…