HVAC Terms Glossary
In the ever-evolving world of Heating, Ventilation, and Air Conditioning (HVAC), staying informed about industry-specific terminology is essential for professionals and companies alike. Whether you're an HVAC technician, installer, engineer, or business owner, understanding the precise definitions and applications of common terms can enhance communication, improve system design, and ensure optimal performance. This glossary serves as a valuable resource, compiling key HVAC terms and their clear, concise explanations to support your expertise and operations. From fundamental concepts like BTU and SEER to advanced technologies such as Variable Refrigerant Flow (VRF) and Building Energy Management Systems (BEMS), our comprehensive collection is designed to keep you informed and proficient in delivering top-notch HVAC solutions. Explore each entry to deepen your knowledge and stay ahead in the competitive HVAC industry.
A
AC (Air Conditioner)
A system or device designed to cool and dehumidify indoor spaces by removing heat and circulating conditioned air.
AC (Alternating Current)
An electrical current that periodically reverses direction, commonly used to power HVAC motors and equipment.
ACH (Air Changes Per Hour)
The number of times the air within a defined space is replaced by fresh or conditioned air each hour through ventilation systems.
ACCA (Air Conditioning Contractors of America)
A leading association representing HVAC contractors, promoting best practices and industry standards.
ACIS™ (Airedale Controls Integrated Systems)
A building energy management system that integrates and optimizes various HVAC and building services for enhanced efficiency.
ACRIB (Air Conditioning and Refrigeration Industry Board)
A regulatory body in the UK overseeing standards and practices within the air conditioning and refrigeration industries.
Adiabatic Cooling
A cooling process that reduces air temperature through the expansion of air without exchanging heat with the environment.
Acoustical
Pertaining to sound management and noise control within HVAC systems to ensure quiet operation and comfort.
AFUE (Annual Fuel Utilization Efficiency)
A measure of a furnace's or boiler's efficiency, indicating the percentage of fuel converted into usable heat over a year.
AFUE (Annual Fuel Efficiency Ratio)
Similar to AFUE, it assesses the efficiency of heating systems by comparing heat output to fuel consumption annually.
AGA (American Gas Association)
An organization representing the natural gas industry, advocating for policies and standards that support gas usage.
AHRI (Air-Conditioning, Heating, and Refrigeration Institute)
A trade association that sets performance standards and certifications for HVACR equipment.
Air-cooled System
An HVAC system that uses air to dissipate heat from the refrigerant in the condenser, typically located outdoors.
Air Diffuser
A device installed in ductwork that distributes conditioned air evenly throughout a space, often featuring adjustable vanes.
Air Flow Volume
The quantity of air moved by an HVAC system, measured in cubic feet per minute (CFM).
Air Handling Unit (AHU) / Air Handler (Blower)
An indoor component of an HVAC system that conditions and circulates air, including fans, filters, and coils.
Ambient
Refers to the surrounding environmental conditions, particularly temperature and pressure, affecting HVAC performance.
Application
The specific location or context where an HVAC system or component is installed and utilized.
ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers)
A global professional society advancing HVAC&R technologies and setting industry standards.
Azeotrope/Azeotropic Mixture
A refrigerant blend that maintains a consistent composition in vapor and liquid phases, making separation by distillation impossible.
Azeotropic Point
The specific temperature at which an azeotropic mixture boils, maintaining identical vapor and liquid compositions.
B
BTU (British Thermal Unit)
A unit of energy representing the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.
BTU/h (British Thermal Units per Hour)
A measure of the heating or cooling power of an HVAC system, indicating the number of BTUs transferred each hour.
BEMS (Building Energy Management System)
A computerized system that monitors and controls building services like HVAC, lighting, and power to optimize energy usage.
Blend
A combination of two or more refrigerants mixed in specific proportions to achieve desired performance characteristics.
BREEAM (Building Research Establishment Environmental Assessment Methodology)
A global standard for assessing the sustainability and environmental performance of buildings.
Bubble Point
The pressure at which a liquid refrigerant begins to vaporize, initiating the phase change in the refrigeration cycle.
Burner
A component in heating systems where fuel is combusted to produce heat for distribution throughout a building.
Burner Orifice
The nozzle through which fuel enters the burner, controlling the flow rate for efficient combustion.
C
Capacity
The total heating or cooling output an HVAC system can deliver, typically measured in BTUs or tons.
Capillary Tube
A small-diameter tube used as a metering device in HVAC systems to regulate refrigerant flow based on pressure differences.
Carbon Usage Effectiveness (CUE)
A metric assessing the ratio of total carbon emissions from a data center to its IT equipment energy consumption.
Celsius
A temperature scale where water freezes at 0°C and boils at 100°C under standard atmospheric conditions.
CFM (Cubic Feet per Minute)
A unit measuring the volume of air moved by an HVAC system per minute.
Charge (Refrigerant Charge) / Refrigerant Charge
The specific amount of refrigerant required in an HVAC system for optimal performance, usually measured in kilograms or pounds.
Chiller
A machine that removes heat from a liquid via a refrigeration cycle, used to cool water or glycol solutions for HVAC systems.
Chilled Water System
An HVAC setup where chilled water circulates through a building to provide cooling, typically supplied by a central chiller.
CIBSE (Chartered Institution of Building Services Engineers)
A professional body in the UK focused on building services engineering, including HVAC design and implementation.
CITB (Construction Industry Training Board)
An organization providing training and support for professionals in the construction and HVAC industries.
CFC (Chlorofluorocarbon) / CFCs
A class of refrigerants known for their ozone-depleting properties, largely phased out due to environmental regulations.
Coefficient of Performance (COP)
A ratio that measures the efficiency of an HVAC system, comparing the amount of heating or cooling provided to the energy consumed.
Compressor
A key HVAC component that pressurizes refrigerant gas, facilitating the heat exchange process in the refrigeration cycle.
Constant Air Volume (CAV)
An HVAC system type where the airflow rate remains constant, and temperature is adjusted to meet heating or cooling demands.
Condenser
The part of an HVAC system where refrigerant releases absorbed heat and transitions from a gas back to a liquid.
Condenser Coil
The coil within the condenser unit where heat is expelled from the refrigerant to the outside air.
Condenser Fan
A fan that moves air across the condenser coil to aid in the heat dissipation process.
Condensing Unit
A complete HVAC unit that includes the compressor, condenser coil, and fan, typically installed outdoors.
Condensate
The liquid water produced when humid air is cooled and dehumidified by an HVAC system.
Controls
The systems and devices used to regulate HVAC operations, including thermostats, sensors, and automated controllers.
Conduction
The transfer of heat through direct contact between materials, one being warmer than the other.
Convection
The transfer of heat through the movement of fluids or gases, driven by temperature-induced density changes.
Cooling Tower
A device that removes heat from an HVAC system by transferring it to the atmosphere through the evaporation of water.
CRAC (Computer Room Air Conditioning)
Specialized air conditioning units designed to maintain precise environmental conditions in data centers.
CRAH (Computer Room Air Handling)
Units that manage and distribute conditioned air within computer rooms to ensure optimal cooling.
CWR (Chilled Water Return)
The return flow of chilled water back to the chiller after it has circulated through the building.
CWS (Chilled Water Supply)
The supply of chilled water from the chiller to the various air handling units or cooling coils in a building.
D
Damper
A device within ductwork that regulates airflow by adjusting the opening size, controlling the volume and direction of air.
Data Centre
A facility housing computer systems and related components, requiring precise HVAC control to maintain optimal operating conditions.
Decant/Receiver
Storage containers used for temporarily holding refrigerant during maintenance or system servicing.
Dehumidifier / Dehumidification
Equipment or processes that remove excess moisture from the air to maintain desired humidity levels and enhance comfort.
Density
The mass of a substance per unit volume, influencing how air moves and behaves within HVAC systems.
Degree-Day
A measure used to estimate heating or cooling requirements based on the deviation of outdoor temperatures from a base value, typically 65°F.
Dew Point
The temperature at which air becomes saturated with moisture, leading to condensation.
Direct Expansion Systems (DX)
HVAC systems where refrigerant directly absorbs and releases heat within the conditioned space without using an intermediate fluid.
Downflow Furnace
A furnace configuration where air enters from the top and exits at the bottom, suitable for spaces with ceiling-mounted vents.
Downflow Air Conditioning
Systems that discharge conditioned air downward, commonly used in settings like office spaces and computer rooms.
Drop-in Refrigerant
Refrigerants that can replace existing ones in HVAC systems without requiring significant modifications to the system infrastructure.
Duct
Channels used to distribute conditioned air throughout a building, encompassing supply, return, and exhaust ducts.
E
EER (Energy Efficiency Ratio)
A metric indicating the cooling efficiency of an HVAC system, calculated as the ratio of cooling capacity (BTU) to electrical input (watts) under specific conditions.
EC Fan (Electronically Commutated Fan)
Fans equipped with electronically controlled motors that offer higher efficiency and variable speed operation compared to traditional AC motors.
Economizer / Economiser
A system component that reduces energy consumption by utilizing outside air for cooling when conditions are favorable, thereby decreasing reliance on mechanical cooling.
Electronic Expansion Valve (EEV)
A device that precisely controls refrigerant flow into the evaporator using electronic signals, enhancing system efficiency and performance.
Energy Reuse Effectiveness (ERE)
A measure of how effectively a data center reuses energy, calculated as the ratio of reused energy to total energy consumed.
Energy Reuse Factor (ERF)
The proportion of energy used within a data center that is successfully reused elsewhere within the facility.
Energy Star®
A certification program by the EPA recognizing energy-efficient products and systems that help reduce environmental impact.
Energy Technology List (ETL) / ECA Scheme
A government program offering tax incentives for businesses investing in energy-efficient equipment that meets specific criteria.
Enthalpy
The total heat content of air, combining both sensible and latent heat, essential for analyzing HVAC system performance.
Entropy
A thermodynamic property representing the degree of disorder or randomness in a system, influencing heat transfer processes.
EPA (Environmental Protection Agency)
A U.S. federal agency responsible for creating and enforcing regulations to protect human health and the environment, including HVAC standards.
Evaporator Coil
The component in an HVAC system where refrigerant absorbs heat from indoor air, facilitating the cooling process.
Evaporating Temperature
The temperature at which refrigerant vaporizes within the evaporator, essential for efficient heat absorption.
Expansion Valve
A device that regulates the flow of refrigerant into the evaporator, maintaining appropriate pressure and temperature for effective cooling.
Thermostatic Expansion Valve (TEV)
A precise expansion valve that adjusts refrigerant flow based on temperature changes, ensuring optimal evaporator performance.
F
Fahrenheit
A temperature scale where water freezes at 32°F and boils at 212°F under standard atmospheric conditions.
Fan / Fan Coil Unit (FCU)
A device that circulates air across heating or cooling coils to distribute conditioned air within a space.
Filter / Filter-Drier
Components that remove dust, debris, and moisture from the air or refrigerant, protecting HVAC system parts and maintaining efficiency.
Flue
A vent pipe that directs combustion gases from heating appliances to the outside, ensuring safe removal of byproducts.
Fluorocarbon
Chemical compounds containing fluorine and carbon, widely used as refrigerants due to their stability and efficiency.
Footprint
The physical space occupied by an HVAC unit or system within a building or facility.
Furnace
A heating device that combusts fuel to generate heat, which is then distributed throughout a building via airflow systems.
F-Gas / F-Gas Regulation
A category of refrigerants containing fluorine, subject to regulations aimed at reducing their environmental impact through restrictions and reporting requirements.
Fuse
An electrical safety device that interrupts the current flow in the event of an overload, protecting HVAC systems from electrical damage.
G
GAMA (Gas Appliance Manufacturers Association)
An industry group representing manufacturers of gas-powered HVAC appliances, promoting standards and innovations.
Gauge Pressure
The pressure measured relative to atmospheric pressure, allowing for positive or negative readings based on system conditions.
Glycol-Cooled System
An HVAC system that uses a glycol-water mixture as a heat transfer fluid to prevent freezing in cooling towers and condensers.
Glide
The temperature range over which a refrigerant blend changes phase, affecting system performance and efficiency.
GWP (Global Warming Potential)
A metric indicating the relative impact of a greenhouse gas on global warming compared to carbon dioxide over a specific timeframe.
Grille
The protective and aesthetic covering over duct openings, directing airflow and preventing debris entry.
H
Heat Exchanger
A component that transfers heat between two or more fluids without mixing them, essential for heating and cooling processes.
Heat Gain
The increase in temperature within a space due to external factors like sunlight, equipment, or occupant activity.
Heat Capacity
The amount of heat required to change the temperature of a substance, influencing HVAC system sizing and performance.
Heat Loss
The reduction in temperature within a space caused by factors such as insulation deficiencies, drafts, or external weather conditions.
Heat Pump
A versatile HVAC device that can provide both heating and cooling by transferring heat between indoor and outdoor environments.
Heat Transfer
The movement of thermal energy from one location to another through conduction, convection, or radiation within HVAC systems.
Hemi-Anechoic Chamber
A specialized testing environment that absorbs sound or electromagnetic waves, used for evaluating HVAC equipment noise levels.
HFC (Hydrofluorocarbon)
A type of refrigerant with no ozone depletion potential but varying degrees of global warming potential, widely used in modern HVAC systems.
HFO (Hydrofluoroolefin)
Advanced refrigerants with low global warming potential and zero ozone depletion potential, serving as environmentally friendly alternatives to HFCs.
HSPF (Heating Seasonal Performance Factor)
A rating that measures the efficiency of heat pumps, calculated by dividing the total heating output by the total energy consumed over a heating season.
Humidity
The amount of water vapor present in the air, affecting comfort levels and HVAC system performance.
Humidifier / Humidification
Devices or processes that add moisture to the air, improving indoor air quality and comfort in dry environments.
Humidistat
A sensor and control device that measures indoor humidity levels and activates the humidifier as needed.
Hydrocarbon Refrigerant (HC)
Natural refrigerants composed of hydrogen and carbon, such as propane (R290) and isobutane (R600a), known for their low environmental impact.
I
Ignition
The process of initiating combustion in heating systems, typically involving the lighting of fuel in burners.
Inverter Compressor
A compressor that uses variable speed technology to adjust its operation based on cooling demand, enhancing efficiency and reducing energy consumption.
Interconnection Agreement
A contract between power systems allowing them to share resources and provide backup power in case of demand spikes or outages.
Internet Service Provider (ISP)
While not directly related to HVAC, ISPs provide internet access services, which can be integral for smart HVAC systems and building management solutions.
K
Kilowatt (kW)
A unit of power representing one thousand watts, used to quantify the energy consumption and capacity of HVAC equipment.
Kyoto Protocol
An international treaty aimed at reducing greenhouse gas emissions, influencing the development and regulation of environmentally friendly HVAC technologies.
L
Latent Cooling Capacity
The portion of cooling provided by an HVAC system that removes moisture from the air, measured in kilograms per kilogram of dry air.
Latent Heat
The heat absorbed or released during a phase change of a substance, such as water vapor condensing into liquid, crucial for understanding dehumidification.
Low Pressure Stage
The phase in a multi-stage refrigeration system where refrigerant is at its lowest pressure and temperature before being compressed again.
M
Make Up Air Unit (MUA)
An HVAC component that introduces fresh outdoor air into a building to replace air exhausted by ventilation systems, maintaining indoor air quality.
Manufacturer Approved System
HVAC systems and components that are certified by the original manufacturer to ensure compatibility and optimal performance when replaced or upgraded.
Media
The material within a filter that captures contaminants like dust, pollen, and microbes to maintain air quality and protect HVAC components.
Microchannel Coil
A compact coil design featuring numerous small channels for improved heat transfer efficiency and reduced refrigerant charge requirements.
Mineral Oil
A lubricant used in some HVAC systems, particularly with certain refrigerants, to ensure smooth operation and reduce wear on components.
N
NATE (North American Technician Excellence)
A certification organization that validates the skills and knowledge of HVACR technicians, promoting industry standards and professionalism.
NEC (National Energy Council / National Electric Code)
Standards and codes governing electrical installations and safety practices within HVAC systems.
NEMA (National Electrical Manufacturers Association)
An association representing electrical equipment manufacturers, setting standards and promoting best practices in the industry.
Natural Refrigerant
Refrigerants derived from natural sources, such as ammonia (R717), carbon dioxide (R744), and hydrocarbons, known for their low environmental impact.
Near Azeotrope
A refrigerant mixture with vapor and liquid phases that are nearly identical in composition, allowing for easier separation and reduced temperature glide.
N+1 Redundancy
A system design strategy ensuring continuous operation by having one additional backup component beyond what is needed for normal operation.
O
ODP (Ozone Depletion Potential)
A measure of a substance's ability to deplete the ozone layer, with higher values indicating greater potential for ozone damage.
Oil Separator
A device in HVAC systems that removes excess oil from refrigerant, preventing compressor damage and maintaining system efficiency.
Orifice
An opening in an HVAC component, such as an expansion valve, that controls the flow rate of refrigerant.
Ozone Depletion Potential (ODP)
See ODP above.
P
Package Unit / Packaged Unit / RTU (Rooftop Unit) / Self-contained System
An all-in-one HVAC system that houses heating and cooling components within a single enclosure, typically installed on rooftops for commercial buildings.
Particulates
Tiny particles in the air, such as dust and pollen, that HVAC filters capture to maintain indoor air quality and protect equipment.
Precision Air Conditioning (PAC) / CRAC (Computer Room Air Conditioning) / CRAH (Computer Room Air Handling)
Specialized HVAC systems designed to maintain strict environmental conditions in data centers and critical facilities, ensuring optimal performance of sensitive equipment.
Plenum / Plenum Space
An enclosed area used to distribute conditioned air throughout a building, often located above ceilings or below floors to facilitate airflow.
Programmable Thermostat
A thermostat that allows users to set schedules for heating and cooling, enhancing energy efficiency and comfort by automatically adjusting temperatures based on occupancy patterns.
Psychrometric Chart
A graphical representation of the properties of air, including temperature, humidity, and enthalpy, used for designing and analyzing HVAC processes.
Psychrometric
Relating to the study of the properties of air-water vapor mixtures, essential for HVAC system design and optimization.
PUE (Power Usage Effectiveness)
A metric for data centers that compares total facility energy consumption to the energy used by IT equipment, indicating overall energy efficiency.
PSI (Pound per Square Inch)
A unit of pressure commonly used in HVAC systems to measure refrigerant pressures and airflow resistance.
PSIA (Pounds per Square Inch, Absolute)
Pressure measured relative to a perfect vacuum, used in HVAC systems to determine absolute pressure levels.
PSIG (Pounds per Square Inch, Gauge)
Pressure measured relative to atmospheric pressure, commonly used in HVAC diagnostics and operations.
PVC (Polyvinyl Chloride)
A durable plastic material used in HVAC ductwork and piping for air distribution and refrigerant lines.
R
Radiant Floor
A heating system where warm water circulates through pipes embedded in the floor, providing comfortable and even heat distribution.
Radiation
The transfer of heat energy through electromagnetic waves without the need for a medium, contributing to overall HVAC heat transfer processes.
Rack
A metal framework used to organize and hold electronic equipment like servers within data centers, requiring precise cooling solutions.
RCI (Rack Cooling Index)
A metric evaluating the percentage of server racks within a data center that maintain optimal inlet temperatures, ensuring efficient cooling.
Reciprocating Compressor
A type of compressor that uses pistons to compress refrigerant, commonly found in smaller HVAC systems due to its reliability and cost-effectiveness.
Recycle
The process of cleaning and reusing recovered refrigerant, ensuring it meets quality standards before being reintroduced into an HVAC system.
Recovery
The extraction and safe storage of refrigerant from an HVAC system during maintenance or decommissioning to prevent environmental release.
Reclaim
The thorough processing of recovered refrigerant to restore it to a condition suitable for reuse, often involving filtering and distillation.
Refrigerant
A fluid used in HVAC systems to absorb and release heat as it cycles between liquid and gas states, essential for the cooling and heating processes.
Refrigerant Charge
The specific quantity of refrigerant required in an HVAC system for optimal operation, determined by manufacturer specifications.
Refrigerant Line
The piping that carries refrigerant between the condenser and evaporator coils within an HVAC system.
Refrigeration Cycle (Vapor Compression Cycle)
The continuous process in HVAC systems where refrigerant absorbs heat in the evaporator, is compressed, releases heat in the condenser, and expands back to its initial state.
Relative Humidity (%rh)
The percentage ratio of the current amount of water vapor in the air to the maximum amount the air can hold at that temperature, affecting comfort and HVAC efficiency.
Remote Electronic Expansion Valve (REEV)
An expansion valve located remotely from the evaporator, providing precise refrigerant flow control for improved system performance.
Retrofit
Upgrading or modifying an existing HVAC system to enhance performance, efficiency, or compatibility with new technologies or refrigerants.
R-number
The designation assigned to a specific refrigerant by standards organizations like ASHRAE, identifying its chemical composition and properties.
R1234ze (HFO Refrigerant)
A fourth-generation hydrofluoroolefin refrigerant with extremely low global warming potential, used as an environmentally friendly alternative in HVAC systems.
R134a (HFC Refrigerant)
Tetrafluoroethane, a common refrigerant with no ozone depletion potential, widely used in automotive and commercial air conditioning applications.
R22 (HCFC Refrigerant)
A hydrochlorofluorocarbon refrigerant with moderate ozone depletion potential, being phased out in favor of more environmentally friendly alternatives.
R407C (HFC Refrigerant)
A blend of hydrofluorocarbons used as a substitute for R22, offering similar performance with no ozone depletion potential.
R410A (HFC Refrigerant)
A high-efficiency refrigerant used in modern air conditioning systems, known for its ability to operate at higher pressures and provide better cooling performance.
Register
The grille and damper assembly at the end of a duct, controlling the direction and flow of conditioned air into a space.
Return Air
The air drawn back into the HVAC system from living or working spaces to be reconditioned and recirculated.
Remote Electronic Expansion Valve (REEV)
See above.
Retrofit
See above.
RCI (Rack Cooling Index)
See above.
R-number
See above.
S
SEER (Seasonal Energy Efficiency Ratio)
A rating that measures the cooling efficiency of HVAC systems over an entire cooling season, with higher values indicating greater efficiency.
Sensible Cooling Capacity
The portion of an HVAC system's cooling output that directly reduces air temperature without affecting moisture levels.
Sensible Heat Ratio (SHR)
The ratio of sensible heat (temperature change) to total heat (sensible plus latent) removed by an HVAC system.
Sensor
Devices within HVAC systems that detect changes in environmental conditions, such as temperature and humidity, to regulate system operations.
Single-Speed
A motor operating at a fixed speed, providing consistent airflow but potentially less energy-efficient compared to variable-speed alternatives.
Scroll Compressor
A compressor using interleaved spiral scrolls to compress refrigerant, known for smooth, quiet operation and high efficiency.
Screw Compressor
A type of compressor that utilizes rotating screws to compress refrigerant, suitable for large-scale HVAC applications due to its high capacity and reliability.
Self-contained System
An HVAC system where all components are housed within a single unit, simplifying installation and maintenance.
T
Thermostat
A control device that monitors indoor temperature and adjusts the HVAC system's heating or cooling output to maintain desired conditions.
Thermostatic Expansion Valve (TEV)
A valve that precisely regulates refrigerant flow into the evaporator based on temperature measurements, ensuring optimal cooling performance.
Thyristor
An electronic component used in HVAC systems to control the flow of electricity, often regulating motor speeds and heater outputs.
Turning Vane
Devices installed within ductwork to guide airflow smoothly through bends and turns, reducing turbulence and improving efficiency.
Ton
A unit of measurement for cooling capacity, equivalent to 12,000 BTUs per hour, commonly used to size air conditioning systems.
Two-Speed
Motors that operate at two distinct speeds, allowing HVAC systems to adjust airflow based on cooling demand for improved efficiency and comfort.
U
Upflow Furnace / Upflow Unit
A furnace design where air enters from the bottom and exits through the top, ideal for spaces with ceiling-mounted vents or limited floor space.
UPS (Uninterruptible Power Supply)
An electrical device that provides emergency power to HVAC systems during outages, ensuring continuous operation of critical equipment like data centers.
V
Vacuum Test
A procedure to remove air and moisture from HVAC refrigerant lines before charging the system, ensuring optimal performance and preventing corrosion.
Variable Air Volume (VAV)
An HVAC system that adjusts the airflow rate to maintain consistent temperature control while optimizing energy usage.
Variable Refrigerant Flow (VRF)
Advanced HVAC systems that modulate refrigerant flow to multiple indoor units, allowing simultaneous heating and cooling in different zones with high efficiency.
Variable-Speed
Motors capable of operating at multiple speeds, providing precise control over airflow and enhancing energy efficiency and system longevity.
Vapour / Vapor
The gaseous state of refrigerant within HVAC systems, essential for the heat exchange process during cooling and heating cycles.
Vapour Barrier/Seal
Materials or systems designed to prevent moisture ingress or egress in critical areas, protecting HVAC components and maintaining indoor air quality.
Ventilation
The process of exchanging indoor air with outdoor air to maintain air quality, control humidity, and ensure occupant comfort.
Voltage
The electrical potential difference that drives current through HVAC system components, essential for their operation.
Volt
The unit of measurement for electrical potential and electromotive force within HVAC systems.
W
Watt
A unit of power representing one joule per second, used to quantify the energy consumption and output of HVAC equipment.
Wet Bulb Temperature
The temperature measured by a thermometer covered with a water-soaked wick, indicating the cooling effect of evaporation and influencing HVAC humidity control.
Water-Cooled System
An HVAC configuration that uses water as the primary medium for heat rejection, typically involving cooling towers and large-scale condensers.
Water Usage Effectiveness (WUE)
A metric evaluating the efficiency of water usage within HVAC systems, particularly in data centers, by comparing total water consumed to IT equipment energy usage.
Z
Zoning
The practice of dividing a building into distinct areas, each controlled by its own thermostat, allowing for customized heating and cooling for enhanced comfort and efficiency.
Zeotrope
Refrigerant blends with varying compositions across different temperatures, allowing for easier separation and maintenance compared to azeotropic mixtures.