HVAC Definitions
A complete glossary of terms related to HVAC
Welcome to our comprehensive HVAC Glossary, your go-to resource for understanding the terminology, concepts, and technology associated with Heating, Ventilation, and Air Conditioning (HVAC) systems. Whether you're a homeowner looking to demystify your home's heating and cooling systems, a student venturing into the world of HVAC, or a seasoned professional brushing up on specific terms, this glossary is designed to be your helpful companion.
HVAC systems are integral to our daily comfort and well-being, playing a crucial role in maintaining the ideal temperature, ensuring fresh air circulation, and managing humidity levels in our living and working environments. However, the technical jargon, acronyms, and industry‐specific language can often be overwhelming. That's where our glossary steps in to make these concepts accessible and understandable.
In this glossary, you'll find an alphabetical list of terms commonly used in the HVAC industry. Each term is accompanied by a clear and concise definition, along with additional context or details where necessary. From essential components like compressors and evaporators to more complex concepts like load calculations and zoning systems, we've covered a wide range of topics to provide you with a thorough understanding of HVAC systems.
Continued Additions
We've also included emerging technologies and modern practices that are shaping the future of HVAC systems, reflecting the industry's commitment to energy efficiency, environmental sustainability, and technological innovation.
Our aim is to make this glossary a dynamic and evolving resource that keeps pace with the latest advancements in the field. We hope it serves as a valuable reference tool, enhancing your knowledge and appreciation of the HVAC systems that keep us comfortable all year round.
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- Air Conditioning
- A system used for cooling and sometimes dehumidifying the air in a building. Air conditioners work by removing heat from indoor air and transferring it outside, creating a more comfortable indoor environment.
- Air Handler
- A unit within an HVAC system that circulates and regulates air. Typically, it consists of a blower, heating or cooling elements, filter racks, and dampers. Air handlers connect to ductwork that distributes the conditioned air throughout the building and returns it to the AHU.
- Airflow
- The movement of air through a space, which is crucial in HVAC systems for maintaining indoor air quality and comfort. Proper airflow ensures efficient operation of the system and distributes conditioned air evenly.
- Air Quality
- Refers to the cleanliness and healthiness of the air inside a building. Good air quality is essential for comfort and health, and HVAC systems play a vital role in filtering and purifying indoor air to remove pollutants and allergens.
- AFUE (Annual Fuel Utilization Efficiency)
- A measure of a gas furnace's efficiency in converting fuel to energy. The higher the AFUE percentage, the more efficient the furnace. For example, an AFUE of 90% means that 90% of the fuel is used to heat the home, and the rest is lost in the combustion process.
- Accumulator
- A component in an HVAC system designed to protect the compressor from liquid refrigerant. It's particularly important in heat pump systems, as it prevents liquid refrigerant from entering the compressor, which can cause damage.
- ACCA (Air Conditioning Contractors of America)
- A non‐profit association in the United States that represents HVAC contractors. They work to promote professional contracting, energy efficiency, and healthy, comfortable indoor environments.
- Actuator
- A device in an HVAC system used to control the opening and closing of dampers in ductwork, regulating airflow. Actuators can be either manual or motorized and are essential for zone control in HVAC systems.
- ASHRAE (American Society of Heating, Refrigerating and Air‐Conditioning Engineers)
- An international technical society dedicated to advancing the arts and sciences of heating, ventilation, air conditioning, and refrigeration to serve humanity and promote a sustainable world.
- Ambient Temperature
- The temperature of the surrounding air. In HVAC terms, it often refers to the outdoor air temperature, which can impact the performance of air conditioning and heating systems.
- Attenuator
- A device used in HVAC systems to reduce noise in the ductwork. It is designed to absorb sound and is often used in situations where duct noise could be disruptive.
- Air Filter
- A component in HVAC systems that removes particles, such as dust, pollen, and bacteria, from the air, improving indoor air quality. Air filters require regular maintenance and replacement to ensure efficiency and cleanliness.
- BTU (British Thermal Unit)
- A unit of measure for heat. It represents the amount of thermal energy required to raise the temperature of one pound of water by one degree Fahrenheit. In HVAC, BTU is used to measure the heating and cooling capacity of equipment.
- Boiler
- A heating system that heats water or generates steam to provide heating through radiators or a hydronic heating system. Boilers are commonly used in residential and commercial buildings for efficient heating solutions.
- Blower Motor
- A component in HVAC systems that drives the fan or blower, circulating air through the ducts and into the space. Blower motors can be single‐speed, multi‐speed, or variable‐speed, affecting the efficiency and control of airflow.
- Bypass Damper
- A device in ductwork that allows air to bypass a section of the system. It's often used in zoned HVAC systems to maintain proper air pressure and ensure consistent temperatures in different areas of a building.
- Balancing (Air/Water)
- The process of adjusting an HVAC system to distribute the correct amount of air or water flow to different areas in a building, ensuring optimal performance and comfort.
- Building Automation System (BAS)
- A system that automates the control of various building systems, including HVAC, lighting, and security. BAS can enhance energy efficiency, reduce operating costs, and improve occupant comfort.
- Backdraft Damper
- A damper installed in the ductwork that prevents outside air from flowing back into the system. It's particularly important in exhaust systems to prevent contaminated air from re‐entering the building.
- Barometric Relief
- A method or device used in HVAC systems to maintain a specific air pressure within a space. It works by automatically adjusting to allow excess air to escape, thereby balancing the pressure.
- Brazing
- A process used in HVAC for joining metal parts (typically copper) by melting and flowing a filler metal into the joint. Brazing is stronger than soldering and is commonly used in piping and refrigeration systems.
- British Standard Pipe (BSP)
- A standard for screw threads commonly used in the plumbing and pipe fitting industry, including HVAC systems. It's crucial for ensuring proper fitting and sealing in piping connections.
- Bimetal
- A temperature‐sensing element made of two dissimilar metals joined together. It's used in some thermostats and controls in HVAC systems to sense temperature changes and activate switches or other controls.
- Buffer Tank
- A tank used in HVAC systems, particularly in hydronic heating or cooling systems, to store hot or chilled water. The buffer tank helps to stabilize temperature fluctuations and improve system efficiency.
- BACnet (Building Automation and Control Networks)
- A communication protocol for building automation and control systems, including HVAC. It allows different systems and devices to communicate with each other, enhancing integration and control.
- Condenser
- A component in air conditioning and refrigeration systems that condenses a substance from its gaseous to its liquid state, thereby releasing heat. In HVAC systems, the condenser is typically part of the outdoor unit.
- Compressor
- A key part of an air conditioning or refrigeration system, the compressor increases the pressure of refrigerant gas and moves it through the system. It's often considered the heart of the system.
- CFM (Cubic Feet per Minute)
- A measure of airflow volume, indicating how many cubic feet of air pass by a stationary point in one minute. In HVAC, CFM is used to gauge the effectiveness of the air distribution system.
- Chiller
- A machine that removes heat from a liquid via a vapor‐compression or absorption refrigeration cycle. This chilled liquid can then be circulated through a heat exchanger to cool equipment or another process stream.
- Condensate
- The liquid that forms when air is cooled below its dew point and moisture condenses. In HVAC systems, condensate is often seen as water dripping from an air conditioner's indoor unit or drain line.
- Carbon Monoxide (CO)
- A colorless, odorless gas that can be harmful when inhaled in large amounts. It's important for HVAC systems, especially those that burn fossil fuels, to have proper ventilation to prevent CO buildup.
- Coil
- Refers to the serpentine loops, usually made of copper or aluminum, through which refrigerant flows. In HVAC systems, there are typically two types of coils: evaporator coils (which absorb heat) and condenser coils (which release heat).
- COP (Coefficient of Performance)
- A measure of efficiency for a heating or cooling system. It represents the ratio of useful heating or cooling provided to the energy consumed. Higher COP values indicate a more efficient system.
- Compressor Overload Protector
- A safety device that shuts off the compressor if it becomes dangerously hot or draws too much power, helping to prevent damage and potential failures.
- Central Air Conditioning
- A system that cools and dehumidifies air in multiple rooms or an entire building through one central location. It typically includes a compressor, condenser, and evaporator, and uses ducts to distribute the conditioned air.
- Capacitor
- An electrical component that stores and releases electrical energy. In HVAC systems, capacitors are used with motors, like those in the compressor and blower motor, to provide a starting boost and stabilize running power.
- Condensate Pump
- A pump used to remove water (condensate) that's been collected in a catch pan, typically found in central air conditioning systems, furnaces, and dehumidifiers.
- CFCs (Chlorofluorocarbons)
- Chemical compounds once commonly used as refrigerants in air conditioning systems. Due to their harmful effect on the ozone layer, CFCs have been largely phased out and replaced with more environmentally friendly substances.
- Ductwork
- The system of ducts used to transport air from the HVAC unit throughout the building. Properly designed and maintained ductwork is crucial for efficient air distribution and indoor comfort.
- Damper
- A device installed in ductwork that regulates airflow by opening or closing. Dampers are used to balance airflow and control the temperature in different zones of a building.
- Diffuser
- An outlet device mounted on the ceiling or wall that spreads the conditioned air in various directions. Diffusers are designed to mix the conditioned air with the existing air in the room effectively.
- Dehumidifier
- A device that removes excess moisture from the air. In HVAC systems, dehumidifiers help to maintain comfortable humidity levels and prevent problems like mold growth and dampness.
- Dry Bulb Temperature
- A measure of air temperature independent of humidity. It's called 'dry bulb' because the air temperature is measured without the influence of moisture, as opposed to wet bulb temperature which considers humidity.
- Downflow Furnace
- A type of furnace in which air enters the top of the unit and is heated as it moves downward. This design is often used in homes with limited space or in basements where the furnace must fit under the floor.
- Ductless System
- An HVAC system that provides heating or cooling without the need for ductwork. Commonly known as mini‐split systems, they are often used in additions to homes, small apartments, or rooms where installing ductwork is impractical.
- Drain Pan
- Also known as a condensate pan, this is a tray placed under the evaporator coil to catch condensation as it drips off the coil, preventing water damage and leaks.
- Dew Point
- The temperature at which air becomes saturated with moisture and dew can form. Understanding dew point is important in HVAC for controlling humidity and preventing condensation problems.
- Duct Sealing
- The process of sealing joints, seams, and gaps in ductwork to prevent air leaks. Proper duct sealing improves the efficiency of the HVAC system and reduces energy costs.
- Delta T (ΔT)
- Stands for 'temperature difference.' In HVAC, it often refers to the difference in temperature between the air entering and the air exiting a system component, like a coil, indicating the effectiveness of heat transfer.
- Duct Insulation
- Insulation material wrapped around ductwork to prevent heat loss or gain and condensation. Insulating ducts is important for maintaining energy efficiency in HVAC systems.
- Demand Response
- A program in which consumers reduce or shift their electricity use during peak periods in response to time-based rates or other forms of financial incentives. This concept is increasingly being integrated into smart HVAC systems for energy savings.
- Evaporator Coil
- A part of an HVAC system where the refrigerant absorbs heat from the air, causing it to evaporate. In air conditioning systems, this component is typically located inside or near the air handler where it cools the indoor air.
- Energy Efficiency Ratio (EER)
- A measure of how efficiently an air conditioning system will operate when the outdoor temperature is at a specific level. It's calculated by dividing the cooling capacity (in BTUs per hour) by the power input (in watts).
- Exhaust Ventilation
- The process of removing air from inside a building to the outside. This is crucial for eliminating pollutants, moisture, and odors, and for maintaining indoor air quality.
- Expansion Valve
- A device in an HVAC system that controls the amount of refrigerant released into the evaporator, thereby controlling the cooling process.
- Economizer
- A system that reduces energy consumption by using outside air to cool a building. When the outdoor air is cooler than the indoor air, the economizer brings in the cooler air, reducing the need for artificial cooling.
- Energy Recovery Ventilator (ERV)
- A device that exchanges stale indoor air with fresh outdoor air, while also transferring heat and moisture between the incoming and outgoing air streams, thus saving energy.
- Electronic Air Cleaner (EAC)
- A device that uses electrical charges to filter and remove particles from the air, like dust, pollen, and smoke. It's more effective than standard air filters and is used in HVAC systems to improve indoor air quality.
- Evaporative Cooler
- Also known as a swamp cooler, this device cools air through the evaporation of water, which is an energy‐efficient alternative to traditional air conditioning in certain climates.
- End Cap (in ductwork)
- A cap or cover used to seal the end of a duct, preventing air leakage and ensuring that air is directed to the intended locations.
- Entalpy
- A term used in thermodynamics to describe the total heat content of air. In HVAC, it's important for calculating the energy efficiency of heating and cooling processes.
- Electric Resistance Heating
- A type of heating system where electric current is used to heat a resistant element, which then radiates heat to the surrounding area. It's simple but often less energy-efficient than other heating methods.
- Energy Star
- A program run by the U.S. Environmental Protection Agency (EPA) that certifies buildings and products for energy efficiency. HVAC systems with the Energy Star label meet strict energy efficiency guidelines set by the EPA.
- EER (Energy Efficiency Ratio)
- A measure of how efficiently an air conditioning unit uses electricity. It's calculated by dividing the cooling capacity by the power input. Higher EER ratings indicate more efficient equipment.
- Furnace
- A heating system that warms air which is then distributed throughout a building via ductwork. Furnaces can be powered by various fuel sources, including natural gas, propane, oil, or electricity.
- Filter Drier
- A device in HVAC systems that removes moisture and contaminants from the refrigerant. This helps to prevent blockages and maintain the efficiency and longevity of the system.
- Freon
- A brand name for a type of refrigerant used in air conditioning systems. It's important to note that some Freon types have been phased out due to environmental concerns.
- Fan Coil Unit (FCU)
- A simple device consisting of a heating or cooling coil and fan. It's part of an HVAC system and is typically used to control the temperature in a single room or zone.
- Flow Rate
- In HVAC, this refers to the volume of air, water, or refrigerant moving through the system. Proper flow rate is crucial for the efficiency and effectiveness of HVAC systems.
- Flue
- A duct or opening that conveys exhaust gases from a furnace, water heater, boiler, or fireplace to the outdoors. Proper flue design is essential for safety and efficiency.
- Fresh Air Intake
- A feature in HVAC systems that brings in fresh outdoor air to replace indoor air that has become stale or polluted. This is important for maintaining good indoor air quality.
- Fan Limit Switch
- A control device in furnaces that turns the fan on and off based on the temperature within the furnace. It helps to prevent the system from overheating and ensures efficient operation.
- Fancoil
- An HVAC component that consists of a coil and a fan, used to either heat or cool the air. Fancoils are often used in split system air conditioners.
- Fire Damper
- A safety device installed in ductwork that closes automatically in the event of a fire to prevent the spread of flames and smoke through the ducts.
- Foot Candle
- A measure of light intensity, indicating how much light is received from a source one foot away. While not directly an HVAC term, it's relevant in building design and comfort levels.
- Fahrenheit
- A temperature scale commonly used in the United States to measure air temperature in HVAC systems. The freezing point of water is 32 degrees Fahrenheit and the boiling point is 212 degrees Fahrenheit.
- Flex Duct
- A type of lightweight, flexible ductwork used in HVAC systems. It's easier to install than rigid ductwork and is commonly used in residential applications.
- Grille
- An opening with several slats that is installed in ductwork and allows air to return to the HVAC system. Grilles do not have dampers and cannot regulate airflow.
- Gas Furnace
- A type of furnace that uses natural gas or propane as a fuel source to heat air. Gas furnaces are known for their efficiency and are a common heating option in many homes and buildings.
- Geothermal Heat Pump
- A central heating and cooling system that transfers heat to or from the ground. It uses the earth as a heat source in the winter or a heat sink in the summer, offering high efficiency.
- Glycol System
- A type of HVAC system that uses glycol (a type of antifreeze) mixed with water in its hydronic (water-based) heating and cooling systems. Glycol prevents the system from freezing in cold temperatures.
- Galvanized Steel
- Steel that has been coated with zinc to prevent rusting. It is commonly used in ductwork for HVAC systems due to its durability and resistance to corrosion.
- Gauge Pressure
- The pressure of a system, measured relative to the surrounding atmospheric pressure. In HVAC, gauge pressure is often used for measuring refrigerant pressure in a system.
- Grains of Moisture
- A measurement used to describe the amount of moisture in the air. One grain of moisture is equal to 1/7,000 of a pound of water. This is important in HVAC for determining humidity levels.
- Green HVAC
- Refers to environmentally friendly and energy‐efficient heating, ventilation, and air conditioning systems. Green HVAC systems are designed to minimize energy consumption and reduce environmental impact.
- Ground Source Heat Pump
- Another term for geothermal heat pump. It uses the constant temperature of the earth as the exchange medium instead of the outside air temperature.
- Gas Valve
- A component in gas furnaces that regulates the flow of gas into the burner. It's a critical safety feature that ensures the correct amount of fuel is delivered to the burner.
- Gasket
- A seal used in HVAC equipment to prevent leaks of air or refrigerants. Gaskets are typically made from flexible materials like rubber or silicone.
- Generator
- In the context of HVAC, it refers to a backup power source that can run heating or cooling systems during a power outage. Generators are especially important in critical applications where maintaining temperature is essential.
- Grains per Pound (GPP)
- A measure of the amount of moisture in the air. It is used in the HVAC industry to calculate the humidity level of a given environment.
- Heat Pump
- A device that transfers heat from one place to another, either heating or cooling a space. It works like an air conditioner in reverse, extracting heat from the air, ground, or water.
- Humidifier
- A device that adds moisture to the air to increase humidity levels. This is particularly useful in dry climates or during winter when indoor air tends to become dry due to heating.
- HVAC (Heating, Ventilation, and Air Conditioning)
- This term encompasses the systems used for moving air between indoor and outdoor areas, along with heating and cooling both residential and commercial buildings.
- Heat Exchanger
- A component in furnaces and boilers that transfers heat from the combustion gases to the air or water that is circulated through the HVAC system.
- HERS Index (Home Energy Rating System Index)
- A scoring system that measures a home's energy efficiency. A lower HERS Index score indicates better energy efficiency.
- Hydronic Heating
- A type of heating system that uses hot water or steam to heat a space. This system typically involves boilers, radiators, and/or underfloor heating systems.
- HVACR
- An extended acronym for Heating, Ventilation, Air Conditioning, and Refrigeration. It's often used to include the broader range of services provided by HVAC professionals, including refrigeration.
- Heat Load
- The amount of heating required to maintain a desired temperature in a building. It's influenced by factors like building size, insulation, climate, and window size.
- Humidistat
- A device used to control the humidity level in a space. It works by turning a humidifier or dehumidifier on and off based on the desired humidity setting.
- HSPF (Heating Seasonal Performance Factor)
- A measure of the efficiency of a heat pump. It calculates the total heating output (including electricity used) over the heating season divided by the total electricity consumed during the same period.
- HVAC Zoning
- A method of heating or cooling different areas of a building separately for enhanced comfort and efficiency. It typically involves the use of dampers in the ductwork and individual thermostats for each zone.
- High-Efficiency Particulate Air (HEPA) Filter
- A type of air filter that can theoretically remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 microns.
- HFCs (Hydrofluorocarbons)
- Compounds used as refrigerants in air conditioning systems, replacing older substances that were harmful to the ozone layer. HFCs are more environmentally friendly but still contribute to greenhouse gas effects.
- IAQ (Indoor Air Quality)
- Refers to the air quality within and around buildings, especially as it relates to the health and comfort of building occupants. Good IAQ is crucial for a healthy living environment and is influenced by factors like pollutants, humidity, and ventilation.
- Inverter Technology
- Used in modern HVAC systems, inverter technology enables the speed of the compressor motor to vary, allowing for more precise temperature control and energy efficiency.
- Insulation
- Material used to prevent the loss of heat or cool air within a building. Insulation is key in maintaining energy efficiency in HVAC systems, reducing the amount of energy required for heating or cooling.
- Ionizer
- A device often found in air purifiers that uses electrically charged ions to remove particles like dust and bacteria from the air. Ionizers can improve indoor air quality by reducing airborne pollutants.
- Impeller
- A type of rotor used in some HVAC system components, like fans or blowers, to increase (or decrease) the pressure and flow of a fluid.
- Integrated HVAC System
- A system that combines multiple HVAC technologies into a single, unified solution for heating, cooling, and ventilation. Integrated systems can improve efficiency and ease of use.
- Indoor Coil
- Part of an air conditioner or heat pump that is located inside a building. The indoor coil, or evaporator coil, absorbs heat from the indoor air, cooling it before it is circulated back into the room.
- Isolation Valve
- A valve used in HVAC systems to isolate certain components for maintenance or troubleshooting. This allows for servicing without disrupting the entire system.
- Intake Vent
- An opening in a building's structure that allows fresh air to enter into the HVAC system. Proper intake vent placement and sizing are critical for maintaining effective ventilation.
- Ignitor
- A component in a gas furnace that ignites the fuel, starting the combustion process. Modern systems often use electronic ignitors instead of pilot lights for better efficiency and reliability.
- Insulated Ducts
- Ductwork that is wrapped or coated with insulating material. Insulating ducts helps to maintain the temperature of the air as it travels through the system, increasing efficiency and reducing energy loss.
- Infrared Heater
- A heating device that uses infrared rays to heat a space. These heaters emit infrared light which is absorbed by objects and surfaces, warming them directly.
- ICP (Indoor Coil Protection)
- A coating or treatment applied to the indoor coil of an HVAC system to protect it from corrosion, improve efficiency, and extend the life of the coil.
- Joule
- In HVAC, a joule is a unit of energy. It's used to measure the amount of energy required to perform work, like heating or cooling a space. One joule is equal to the energy transferred when one watt of power is applied for one second.
- Jacket
- This term refers to the outer covering of an HVAC component, such as a boiler or furnace. The jacket serves to insulate the component, improve efficiency, and enhance safety by protecting against contact with hot surfaces.
- J-T (Joule-Thomson) Effect
- In refrigeration and air conditioning systems, this effect describes the temperature change of a gas or liquid when it is forced through a valve or porous plug while kept insulated so that no heat is exchanged with the environment. This principle is key in the operation of many cooling systems.
- Jumper
- A jumper is a short wire or connector used within the HVAC control system or thermostat. It's used to connect two points together, typically to bypass a particular control or to customize the control system for specific needs.
- Junction Box
- An enclosure within the HVAC electrical system where wires are connected or spliced together. Junction boxes protect wire connections and provide a safe and organized way to house electrical connections.
- JIC (Joint Industrial Council) Fittings
- These are standardized fittings used in HVAC systems, particularly in the refrigeration circuit. They ensure a secure, leak‐proof connection in the system.
- Jet Diffuser
- A type of air diffuser used in HVAC systems, designed to handle high air flow rates and provide long throw capabilities. Jet diffusers are often used in large or high‐ceiling spaces where air needs to be distributed over a long distance.
- Jalousie
- A type of window or vent that consists of horizontal slats arranged in parallel. In the context of HVAC, jalousie windows can be opened or closed to control air flow and ventilation in a room.
- Kilowatt (kW)
- A unit of power equal to 1,000 watts. In HVAC, it's used to measure the energy consumption of larger systems. The kilowatt-hour (kWh), a unit of energy, indicates the amount of energy used over time, such as in a billing period for electrical usage.
- Kilowatt‐Hour (kWh)
- A measure of electrical energy equivalent to a power consumption of 1,000 watts for 1 hour. It's commonly used as a billing unit for energy delivered to consumers by electric utilities.
- K‐factor
- In HVAC, the K‐factor is a value that indicates the thermal conductivity of a material, used in calculating heat transfer. A lower K-factor means better insulation properties.
- Kickstart
- A term often used to describe a method or device that helps start a compressor, especially under difficult conditions like low voltage or high head pressures. These devices temporarily boost the starting torque of the motor.
- Kink
- Refers to a bend or fold in flexible ductwork that restricts airflow. Proper installation and maintenance of ductwork are important to avoid kinks that can reduce the efficiency and effectiveness of an HVAC system.
- Knockout
- Pre‐cut, removable sections in electrical boxes or HVAC equipment that allow for the easy entry of electrical cables or ductwork. Removing a knockout creates an opening for wiring or piping while maintaining the integrity of the enclosure.
- K‐type Thermocouple
- A type of thermocouple used for temperature measurement in HVAC systems. It consists of a pair of dissimilar metals, Chromel and Alumel, that produce a voltage in response to a temperature difference.
- Key Duct
- In large building HVAC systems, a key duct is a main branch of the duct system that serves as a primary route for airflow. Proper design and sizing of key ducts are crucial for efficient air distribution.
- K‐Value
- Another term for thermal conductivity. In HVAC, it's used to describe the rate at which heat passes through a material. Insulation materials with a low K-value are more effective in reducing heat transfer.
- Knee Wall
- A short wall, typically less than three feet in height, used to support rafters in the top floor of a building. In HVAC, ensuring proper insulation and ventilation around knee walls is important for maintaining energy efficiency.
- Latent Heat
- The heat absorbed or released by a substance during a phase change (like ice melting or water vaporizing) without a temperature change. In HVAC, managing latent heat is important for effective humidity control.
- Load Calculation
- A mathematical process used in HVAC to determine the right size of a heating and cooling system for a building. It considers factors like size of the building, climate, insulation, window type, and occupancy.
- Louvers
- Slatted devices installed in ducts or walls to regulate airflow. They can be adjusted to control the volume of air allowed to pass through, and they also help in directing the air flow.
- Low-E Glass (Low Emissivity)
- A type of energy‐efficient glass for windows that reflects heat. In HVAC, using low‐E glass can help in reducing the heat gain in summer and heat loss in winter, thereby reducing heating and cooling demands.
- Louvered Coil Guard
- A protective covering with slats (louvers) over an HVAC unit's coil. The guard protects the coil from damage while allowing adequate airflow.
- Limit Switch
- A safety device in a furnace that shuts off the burner if the furnace overheats. If the furnace reaches a dangerous temperature, the limit switch will interrupt power, stopping the heating cycle.
- Liquid Line
- The part of an air conditioning or refrigeration system that carries liquid refrigerant from the condenser to the expansion valve.
- Linear Diffuser
- An air diffuser that distributes air in a linear direction. It's often used in ceiling applications in modern architecture for a streamlined look and effective air distribution.
- Leak Detection
- The process of identifying and locating leaks in an HVAC system. This is crucial for maintaining system efficiency, preventing damage, and ensuring safety, especially in refrigeration systems.
- Laminar Flow
- A type of air flow in which air moves at the same speed and in the same direction, with minimal or no crossover of air streams. Laminar flow is often desired in cleanroom environments.
- Life Cycle Cost
- The total cost of owning an HVAC system over its entire lifespan, including initial purchase, installation, operation, maintenance, and disposal costs. Considering life cycle cost helps in making cost‐effective choices.
- Louvered Doors
- Doors with slats (louvers) designed to allow for air circulation while providing privacy and noise reduction. They can be used for enclosing HVAC equipment while ensuring adequate ventilation.
- LED Lighting
- While primarily known for its use in lighting, LED technology is also incorporated into HVAC systems for control displays and other indicators. LED lighting is energy-efficient and has a long lifespan.
- Manual D
- A protocol used in the HVAC industry for designing residential duct systems. It ensures that ductwork is properly sized and configured for efficient airflow.
- MERV Rating (Minimum Efficiency Reporting Value)
- A standard that rates the overall effectiveness of air filters. Higher MERV ratings indicate finer filtration, meaning fewer dust particles and other airborne contaminants can pass through the filter.
- Modulating Furnace
- A type of furnace that can vary its heating output based on the current need, providing more efficient heating and more consistent indoor comfort levels than traditional furnaces.
- Manifold Gauge
- A device used in HVAC systems to measure the pressure of refrigerants. It consists of multiple gauges and is used for diagnosing and servicing air conditioning and refrigeration systems.
- Make‐Up Air
- Fresh, outside air that's brought into a building to replace exhausted air. This is crucial for maintaining indoor air quality and proper ventilation.
- Microchannel Coil
- A type of condenser or evaporator coil that features flat, aluminum tubes and fins for heat transfer. These coils are compact, efficient, and often used in modern HVAC systems.
- Mixed Air
- In HVAC systems, this refers to the combination of fresh outside air and recirculated indoor air that is used to maintain indoor air quality and temperature.
- Modulating Valve
- A valve that can adjust the flow of liquid or gas in a system incrementally, allowing for precise control of heating or cooling.
- Mini‐Split System
- A ductless HVAC system that consists of an outdoor compressor unit and one or more indoor air‐handling units, connected by a conduit. It's ideal for heating or cooling individual rooms or small spaces.
- Mechanical Ventilation
- A type of ventilation system that uses mechanical means, like fans and ductwork, to circulate fresh air into and out of a building, as opposed to natural ventilation which relies on passive air flow.
- Multizone System
- An HVAC system that can control temperatures in multiple areas or zones independently, offering greater comfort and efficiency than single‐zone systems.
- Motorized Damper
- A damper in the ductwork that is controlled by a motor. It opens or closes automatically to regulate airflow in the HVAC system, often as part of a zoning system.
- Manual J
- A standard calculation used in the HVAC industry for determining the heating and cooling loads of a building. This calculation is essential for properly sizing an HVAC system to match the specific needs of a building.
- Natural Ventilation
- The process of supplying and removing air through an indoor space without the use of mechanical systems, relying instead on natural forces like wind and thermal buoyancy.
- Nitrogen Charge
- Nitrogen is often used in HVAC systems to test for leaks, charge the system, or purge lines. A nitrogen charge refers to the process of filling the system with nitrogen for these purposes.
- NEC (National Electrical Code)
- A set of standards for safe electrical design, installation, and inspection to protect people and property from electrical hazards. In HVAC, adherence to the NEC is essential for safe operation.
- Non-Condensable Gases
- Gases that do not condense at the temperatures and pressures used within a particular HVAC system. Their presence can decrease the efficiency of refrigeration cycles.
- NEMA (National Electrical Manufacturers Association) Ratings
- NEMA ratings define the types of environments in which an electrical enclosure can be used and how well it protects against elements like dust, water, and corrosion.
- Nozzle
- In HVAC, a nozzle can refer to a component in a ventilation system that directs the flow of air into a room. It's often designed to provide a specific airflow pattern.
- NATE (North American Technician Excellence)
- A certification organization for HVAC technicians. NATE‐certified technicians have demonstrated their knowledge and proficiency in HVAC systems through rigorous testing.
- Negative Pressure
- A condition where the air pressure inside a space is lower than the air pressure outside. In HVAC systems, negative pressure can cause problems like poor air quality or backdrafts.
- Non-Programmable Thermostat
- A basic type of thermostat that allows users to set a single temperature, which must be changed manually as needed. It doesn't offer scheduling or advanced features found in programmable models.
- Noise Reduction
- In HVAC, this refers to methods or technologies used to minimize noise produced by heating and cooling systems. This can include soundproofing materials, design modifications, or specific components designed to operate quietly.
- Normal Operating Pressure
- The range of pressures within which an HVAC system or component is designed to operate efficiently and safely.
- Nest Thermostat
- A brand of smart thermostat known for its learning capabilities and energy‐saving features. It can adapt to a user's schedule and preferences and can be controlled remotely.
- NEMA Frame Size
- In HVAC, this refers to the standardized dimensions of electric motor mounting flanges and shafts as defined by the National Electrical Manufacturers Association.
- Orifice
- A small opening, often in a nozzle or as part of the HVAC system's components, that controls the flow of liquid or gas. In HVAC, orifices are critical in metering devices and in distributing refrigerants.
- Outdoor Unit
- In a split HVAC system, the outdoor unit contains components like the compressor, condenser coil, and fan. It's part of the system that expels heat from the refrigerant to the outside air.
- Occupancy Sensor
- A device that detects the presence of people within a space and adjusts the HVAC system accordingly. This can improve energy efficiency by reducing heating or cooling in unoccupied areas.
- Overload Protector
- A safety device that prevents an electric motor or other component in an HVAC system from overheating by shutting down the system when it draws too much power.
- Ozone Depletion
- Refers to the reduction of the ozone layer in the Earth's stratosphere. Certain HVAC refrigerants, like older chlorofluorocarbons (CFCs), have contributed to ozone depletion, leading to their phase‐out and replacement with more environmentally friendly options.
- Offset Duct
- A ductwork configuration where two sections of duct are not in a straight line and an offset is used to align them. This is often necessary due to physical obstacles in a building's structure.
- Ohm
- A unit of electrical resistance. In HVAC systems, ohm measurements can be used to diagnose electrical problems, like bad motors or malfunctioning controls.
- On-Board Diagnostics
- Modern HVAC systems often include diagnostic systems that monitor the operation and alert users to any maintenance needs or system failures, enhancing efficiency and convenience.
- Open System
- An HVAC system where the refrigerant or other working fluid is exposed to the atmosphere. This is in contrast to a closed system, where the fluid is contained.
- Operating Cost
- The ongoing cost of running an HVAC system, including energy consumption, maintenance, and repairs. Energy‐efficient systems typically have lower operating costs over time.
- Outdoor Air Damper
- A component of the HVAC system that controls the amount of outdoor air entering the system. It plays a crucial role in ventilation and maintaining indoor air quality.
- Oxidation
- A chemical reaction involving oxygen that can lead to deterioration of some HVAC components, such as corrosion in metal parts. Proper maintenance helps to minimize oxidation-related issues.
- OEM (Original Equipment Manufacturer) Parts
- These are components produced by the manufacturer of the HVAC equipment. Using OEM parts in repairs and maintenance ensures compatibility and reliability.
- Package Unit
- A type of HVAC system where all components, including the compressor, coils, and fan, are housed in a single unit. Package units are typically installed outdoors and are common in commercial buildings.
- Plenum
- A central distribution box in an HVAC system that connects to the ductwork. It takes in supply or return air, then channels it to different areas of the building.
- Programmable Thermostat
- A thermostat that allows users to set different temperatures for different times of the day or days of the week. It helps in energy saving by adjusting the temperature based on occupancy or time.
- Purge System
- A system used in large chillers to remove non‐condensable gases from the refrigerant, improving efficiency and performance.
- Pressure Switch
- A safety device in HVAC systems that shuts off the system if the pressure gets too high or too low. It helps prevent damage to equipment.
- Pascal (Pa)
- A unit of pressure in the International System of Units (SI). In HVAC, it is used for measuring small differences in air pressure, crucial for system design and troubleshooting.
- Psychrometrics
- The study of the properties of air and water vapor mixtures. In HVAC, psychrometric charts are used to calculate heating and cooling loads, and to design systems.
- PTAC (Packaged Terminal Air Conditioner)
- A self‐contained heating and air conditioning unit commonly found in hotels. It is installed through a wall and typically has controls accessible from within the room.
- Pilot Light
- A small flame that is used to ignite the gas in older gas furnaces. Modern systems often use electronic ignition systems instead.
- PVC (Polyvinyl Chloride)
- A type of plastic commonly used for venting in high-efficiency furnaces and water heaters. It is corrosion-resistant and can handle the low-temperature exhaust of these systems.
- Pressure Balancing
- A process in HVAC to ensure that different areas of a building have the same air pressure. This is important for comfort and for the efficient operation of the system.
- Piping
- In HVAC, piping refers to the network of pipes used for the distribution of heating or cooling medium, such as water or refrigerant, throughout the system.
- Pump Down
- A procedure in refrigeration systems where the refrigerant is pumped from the evaporator and lines into the condenser and receiver for service or maintenance purposes.
- Quality Air
- This term refers to indoor air that meets a certain standard of cleanliness, free from excessive levels of pollutants, allergens, and other harmful substances. It's essential for health and comfort in indoor environments.
- Quick Connect Fittings
- Special fittings used in HVAC systems that allow for rapid and secure connection of components, such as refrigerant lines, without the need for specialized tools. These are particularly useful for modular or portable HVAC units.
- Quadrant Damper
- A type of damper used in ductwork, typically shaped like a quadrant (a quarter circle), that allows for precise airflow control by rotating to various positions.
- Q‐value
- In HVAC, this represents the rate of heat flow through a material. It's a measure of thermal performance, and a lower Q-value indicates better insulating properties.
- Quiet Operation
- An attribute of HVAC equipment designed to minimize noise during operation. This can be achieved through various means such as insulated cabinets, vibration dampening, and specially designed fan blades.
- Quadra‐Flo
- A method or system used in HVAC to distribute air evenly in four directions. It's often a feature of certain types of air diffusers or grilles, providing more uniform air distribution in a space.
- Quenching
- In HVAC terms, this refers to the rapid cooling of a hot component. For example, quenching is used in some manufacturing processes for metal components of HVAC systems to improve their durability or performance.
- Quarter‐Turn Valve
- A valve that can be opened or closed with a quarter turn. In HVAC systems, these valves are used for their ease of operation and reliability, often in applications where quick control of flow is necessary.
- Q‐R Factor
- A term used in HVAC design and analysis, referring to the flow rate and resistance in duct systems. It's a factor in calculating the pressure drop and energy efficiency of ductwork.
- Qualification Standard
- In HVAC, this often refers to the criteria or standards set by industry bodies or certification agencies that technicians or equipment must meet to be considered qualified or certified.
- Refrigerant
- A chemical compound used in HVAC systems to absorb and transfer heat. Refrigerants change from liquid to gas and back to liquid in the refrigeration cycle.
- Return Air
- The air that is drawn back into an HVAC system for reconditioning and recirculation. This air is typically drawn through return ducts and filters before being heated or cooled again.
- Register
- An adjustable air outlet device that controls the direction and flow rate of air into a room. Registers are typically found on walls, floors, or ceilings.
- Radiant Heating
- A method of heating, often used in floors or panels, that directly warms people and objects in a room rather than heating the air. It provides heat through infrared radiation.
- Reheat Coil
- A component in HVAC systems used to reheat air that has been cooled too much, especially in systems where humidity control is important.
- Relative Humidity (RH)
- A measure of the amount of moisture in the air compared to the maximum amount of moisture the air can hold at that temperature. It is expressed as a percentage.
- Reciprocating Compressor
- A type of compressor in HVAC systems that uses pistons driven by a crankshaft to compress the refrigerant. It's commonly used in smaller systems.
- Roof Top Unit (RTU)
- A type of HVAC system installed on roofs of buildings. RTUs are commonly used in commercial buildings and are self-contained units that include all components needed for the air conditioning process.
- Refrigerant Charge
- The amount of refrigerant in an HVAC system. Proper refrigerant charge is essential for the efficient operation of air conditioning and refrigeration systems.
- Return Duct
- The part of an HVAC system's ductwork that carries air back to the air handler from the building. This air is to be reconditioned, passing through filters before being heated or cooled again.
- Reversing Valve
- A valve in a heat pump that reverses the flow of refrigerant to switch between heating and cooling modes.
- R‐Value
- A measure of thermal resistance used in the building and construction industry. Higher R‐values indicate better insulating effectiveness.
- Radiator
- A heat exchanger device designed to transfer thermal energy from one medium to another for heating a space. It's commonly used in hydronic heating systems.
- Refrigerant Lines
- Tubes or pipes that carry refrigerant between the various components of an HVAC system, such as between the outdoor and indoor units in a split system.
- SEER (Seasonal Energy Efficiency Ratio)
- A measure of air conditioning efficiency calculated as the cooling output during a typical cooling-season divided by the total electric energy input. Higher SEER ratings indicate greater energy efficiency.
- Split System
- A common type of HVAC system that is divided into two main parts: an outdoor unit containing the compressor and condenser, and an indoor unit with the evaporator. It's commonly used in residential settings.
- Supply Air
- The conditioned air that is distributed from the HVAC system into the occupied space through the ductwork and vents.
- Scroll Compressor
- A type of compressor used in HVAC systems, known for its efficiency and reliability. It operates by compressing refrigerant with two interlocking scrolls.
- Setpoint
- The temperature to which a thermostat is set for desired comfort. The HVAC system will work to maintain the indoor temperature at the setpoint.
- Static Pressure
- The pressure exerted by the air within the HVAC system's ductwork. Proper static pressure is necessary for effective airflow and system performance.
- Sensible Heat
- The heat energy that causes a change in temperature of a substance but does not contribute to a change in phase, like from liquid to gas. It's contrasted with latent heat.
- Soffit Vent
- A type of vent used in buildings to allow fresh air to enter into the attic or roof space. It's typically installed in the underside of a building's eaves (soffits).
- Swamp Cooler
- Also known as an evaporative cooler, it cools air through the evaporation of water, ideal for dry and arid climates. It's a cost‐effective and energy‐efficient alternative to traditional air conditioning.
- Smart Thermostat
- An advanced thermostat that can be programmed and controlled remotely through a smartphone or other devices. It often includes features like learning a user's habits and adjusting settings for optimal comfort and energy savings.
- Supply Duct
- The ductwork in an HVAC system that carries conditioned air from the system to the various spaces in a building.
- Suction Line
- The pipe that carries refrigerant in its gaseous state from the evaporator to the compressor in an HVAC system.
- Solar Gain
- The increase in temperature in a space, object, or structure as a result of solar radiation. Managing solar gain is important in HVAC design for energy efficiency.
- Sizing
- The process of determining the appropriate size of an HVAC system or its components for a specific building, based on factors like square footage, climate, and building characteristics.
- Thermostat
- A device that monitors and regulates the temperature of a space by controlling the operation of an HVAC system. Thermostats can be manual or programmable, and more advanced models are "smart," offering remote control and learning features.
- Ton
- A unit of measurement used in HVAC to describe the cooling capacity of an air conditioning system. One ton of cooling is equal to the amount of heat absorbed by one ton of ice causing it to melt completely over a 24-hour period (12,000 BTUs per hour).
- Transformer
- A device in HVAC systems that steps down the voltage from the power source to a level that is safe and usable for the control systems and components within the HVAC unit.
- TXV (Thermostatic Expansion Valve)
- A device in air conditioning and refrigeration systems that regulates the flow of refrigerant to the evaporator, maintaining optimal efficiency.
- Two‐Stage Furnace
- A type of gas furnace that has two levels of heat output: high for cold winter days and low for milder days. This allows for more efficient energy use compared to traditional single‐stage furnaces.
- Thermal Zone
- An area of a building that has similar heating and cooling needs, controlled by a single thermostat. Effective zoning can greatly improve the efficiency and comfort of an HVAC system.
- Trunk Line
- The main ductwork in an HVAC system that delivers air from the heating and cooling equipment to the branch ducts, which then distribute it throughout the building.
- Thermocouple
- A safety device in gas heating systems that shuts off the gas if the pilot light goes out or fails to light. It prevents gas from leaking into the home if there's no flame to burn it.
- Tonnage
- The term used to describe the cooling capacity of an air conditioner. One ton of cooling equals the amount of heat absorbed by one ton of ice melting over 24 hours, or 12,000 BTUs per hour.
- Turndown Ratio
- In heating systems, this refers to the range of the heating output. A higher turndown ratio means the equipment can operate at lower minimum outputs, improving efficiency and comfort.
- Thermal Load
- The amount of heating or cooling that a building needs to maintain the desired temperature. It's determined by factors like building size, insulation, climate, and occupancy.
- Transfer Grilles
- Grilles used to allow air to move between different areas or rooms, aiding in the circulation and balancing of air within an HVAC system.
- Temperature Differential
- The difference in temperature between two points, such as the air temperature and the set point on a thermostat. In HVAC, a small temperature differential can indicate a system's efficiency.
- Upflow Furnace
- A type of furnace in which heated air is pushed upwards into the ductwork. This design is typically used in basements or lower levels of a building, with the furnace blowing warm air upwards to heat a room or space.
- U-Value (or U‐Factor)
- A measure of heat transfer through a building material, such as a window or wall. The U‐Value indicates how well a material insulates; lower U‐Values mean better insulation and greater energy efficiency.
- UV (Ultraviolet) Air Purifier
- A device that uses ultraviolet light to kill or neutralize bacteria, viruses, and other airborne pathogens, improving indoor air quality. These purifiers are often used in HVAC systems to maintain healthy indoor air.
- Unit Heater
- A type of heater that is commonly used in garages or workshops. It is a self‐contained unit, often gas or electric, that provides direct heat to a space.
- Underfloor Heating
- A type of radiant heating system installed beneath the floor, providing even heat distribution across a room. It can be water-based (hydronic) or electric.
- Unidirectional Flow
- An airflow pattern moving in a single direction in a controlled environment, often used in cleanrooms or laboratories to maintain clean and contaminant‐free air conditions.
- Universal Motor
- A type of electric motor that can operate on either AC or DC power. In HVAC, these motors are typically found in portable equipment or tools.
- Ultrasonic Humidifier
- A type of humidifier that uses ultrasonic vibration to produce a fine mist, which is then expelled to add moisture to the air. These are known for their quiet operation.
- Utility Set Fan
- A type of centrifugal fan used in various HVAC applications. It is characterized by its compact design and is often used in commercial and industrial settings.
- Unbalanced System
- Refers to an HVAC system where the air distribution is not even, leading to areas that are either too hot or too cold. Proper balancing is necessary for comfort and efficiency.
- User Interface
- In the context of HVAC, this refers to the controls and displays through which a user interacts with the HVAC system, such as thermostats, control panels, and remote controls.
- U‐Bend
- In HVAC systems, particularly in refrigeration, a U-bend is a U‐shaped section of piping used in the construction of heat exchangers.
- VAV (Variable Air Volume)
- A type of heating, ventilating, and air-conditioning (HVAC) system that varies the airflow at a constant temperature. VAV systems adjust the air volume to meet the demands of the space, leading to improved comfort and efficiency.
- Ventilation
- The process of exchanging or replacing air within any space to provide high indoor air quality, involving temperature control, oxygen replenishment, and removal of moisture, odors, smoke, heat, dust, airborne bacteria, carbon dioxide, and other gases.
- VRF (Variable Refrigerant Flow)
- An HVAC technology that uses refrigerant as the cooling and heating medium. The system is designed to allow for varying degrees of heating and cooling in different zones of a building, providing enhanced comfort and efficiency.
- Volt
- The unit of measure for electric potential or electromotive force. In HVAC systems, voltage is an important consideration for the correct operation of equipment.
- Vent
- An outlet for air or gas in a building's HVAC system. Vents are used to distribute air processed by the system into the building and can be adjustable to control airflow direction and speed.
- Vacuum Breaker
- A device that prevents unwanted backflow of liquids into a system, often used in water supply systems to prevent cross‐contamination.
- Variable Speed Motor
- A motor that can operate at a range of speeds as opposed to a single fixed speed. This type of motor is used in some HVAC systems for more precise control of air flow and energy efficiency.
- Volume Damper
- A damper in the ductwork that regulates the volume of air flowing through the duct. Volume dampers are crucial for balancing air distribution in HVAC systems.
- Ventilator
- An appliance or device that brings fresh air into or expels air out of a space. Ventilators are key components in maintaining indoor air quality and can be part of a larger HVAC system.
- Vent Pipe
- A pipe through which gas or air is vented. In HVAC systems, vent pipes are essential for safe operation, particularly in systems that use combustion, like gas furnaces.
- Viscosity
- In HVAC, this term refers to the thickness or thinness of a liquid (like oil or refrigerant) and its resistance to flow. Proper viscosity is important for the efficient operation of HVAC system components.
- Vapor Barrier
- Material used to prevent moisture from penetrating walls, ceilings, and floors. In HVAC, vapor barriers are important for controlling humidity and preventing mold growth.
- VAV Box (Variable Air Volume Box)
- A component in VAV systems that controls the volume of air delivered to a space, adjusting the airflow based on the current heating or cooling needs.
- Water Source Heat Pump
- A type of heat pump that uses water instead of air as the heat exchange medium. These systems can be more efficient than air-source heat pumps, especially in moderate climates.
- Wet Bulb Temperature
- A measure of air temperature that takes into account humidity, reflecting the cooling effects of evaporation. It's a key factor in HVAC for determining the properties of air and designing effective cooling systems.
- Watt (W)
- A unit of power in the International System of Units (SI) that measures the rate of energy transfer. In HVAC, the wattage of a system indicates its power consumption or output.
- Weatherstripping
- Material used to seal gaps around windows and doors to prevent air leaks. Effective weatherstripping is important in HVAC for maintaining energy efficiency and indoor comfort.
- Whole‐House Fan
- A large fan that helps cool a home by pulling cooler outdoor air through open windows and doors and exhausting warm indoor air through the attic and roof.
- Water Chiller
- A machine that removes heat from a liquid via a vapor‐compression or absorption refrigeration cycle. This chilled liquid can then be used in air conditioning or other processes.
- Working Fluid
- In HVAC systems, particularly in heat pumps and refrigeration cycles, the working fluid is the refrigerant or other medium that absorbs and releases heat.
- Warm Air Furnace
- A type of furnace that heats air and distributes it throughout a building using ductwork. These furnaces can use various fuel sources, including natural gas, oil, or electricity.
- Water Coil
- A type of heat exchanger in an HVAC system that uses water to either heat or cool air. These coils can be part of hydronic heating or cooling systems.
- Wind Baffle
- A device used on outdoor HVAC units to prevent disruption of the system's operation due to wind. It helps in stabilizing the performance of the unit, particularly in windy conditions.
- Water Hammer
- A phenomenon in which a shock wave is sent through a water pipe, often caused by a sudden closure of a valve. In HVAC, this can occur in systems with water circulation, and it may require a water hammer arrestor to prevent damage.
- Wiring Diagram
- A diagram that shows the electrical connections and functions of an HVAC system. It is essential for installation, troubleshooting, and repairing HVAC equipment.
- Wraparound Heat Pipe
- An energy recovery system used in HVAC to pre‐cool the incoming fresh air by using the cool exhaust air, improving energy efficiency without additional mechanical cooling.
- Xenon Lighting
- While not directly related to HVAC, xenon lighting can impact the thermal load in a building. Xenon lights are often used for their bright, clear light and long lifespan. They can generate significant heat, affecting the cooling load in an indoor environment.
- X-Ref (Cross Reference)
- In HVAC parts and systems, an 'X-Ref' or cross‐reference is often used to find compatible parts or replacements. This is useful when dealing with discontinued models or when sourcing parts from different manufacturers.
- Xeriscaping
- This term is more related to landscaping but can indirectly affect HVAC efficiency. Xeriscaping involves designing landscapes to reduce or eliminate the need for irrigation. By reducing water usage and maintaining cooler surroundings through strategic plant placement, xeriscaping can indirectly reduce the cooling load on HVAC systems in dry climates.
- X‐Duct
- While not a standard term, this could refer to any ductwork with a configuration or shape resembling the letter 'X.' In complex ductwork layouts, different sections might be described based on their shapes or configurations.
- X‐Factor in Insulation
- This is an informal term that could be used to describe a variable or unknown factor in insulation effectiveness. In building and HVAC, understanding all factors that contribute to insulation performance, including materials, installation, and environmental conditions, is crucial for energy efficiency.
- Y-Strainer
- A type of strainer used in HVAC systems, shaped like the letter "Y." It's used to protect components such as pumps or valves by filtering out debris from the liquids that pass through the system, ensuring efficient operation and preventing damage.
- Year-Round Comfort
- A term used to describe HVAC systems that are designed to provide comfortable indoor temperatures and air quality in all seasons. It encompasses both heating and cooling capabilities.
- York
- A well-known manufacturer of HVAC systems and equipment. York produces a wide range of heating, cooling, and air conditioning products for residential and commercial applications.
- Yield
- In the context of HVAC, yield can refer to the efficiency or output of a system. For example, it might describe the amount of heating or cooling provided compared to the energy consumed.
- Y‐Terminal
- On a thermostat, the Y‐terminal is typically used to control the cooling system. In a typical setup, when the thermostat calls for cooling, it sends a signal to the Y-terminal to activate the air conditioner.
- Zone
- In HVAC, a zone is an area or section of a building that has distinct heating and cooling needs, controlled independently from other areas. Zoning is used for improving comfort and energy efficiency.
- Zoning System
- An HVAC system that uses dampers in the ductwork to regulate and redirect air to specific areas or zones within a building. Each zone has its own thermostat and control mechanism.
- Zero Energy Building
- A building with zero net energy consumption, meaning the total amount of energy used annually is roughly equal to the amount of renewable energy created on-site. These buildings often use advanced HVAC systems to maximize energy efficiency.
- Zeotropic Refrigerant
- A blend of refrigerants that have different boiling points and evaporate or condense at different rates. This characteristic can affect the efficiency and operation of HVAC systems using these refrigerants.
- Zone Valve
- A valve used to control the flow of water or steam in a hydronic heating or cooling system. Each zone valve is typically controlled by its own thermostat.
- Zigbee
- A wireless communication standard used in some smart HVAC systems for controlling thermostats, sensors, and other components. It allows for remote and automated control of the HVAC system.
- Zoned Control Panel
- The central control unit in a zoned HVAC system that manages the opening and closing of dampers and coordinates the heating or cooling based on the settings of each zone's thermostat.
- Zone Sensor
- A sensor located within an HVAC zone that monitors temperature, humidity, or other environmental conditions, providing feedback to the system to maintain the desired conditions in that zone.
- Zero Ozone Depletion Potential (ODP)
- A characteristic of some refrigerants that indicates they do not contribute to the depletion of the ozone layer. These are more environmentally friendly options in HVAC systems.
- Zinc Coating
- In HVAC, zinc coatings are often applied to components, like ductwork, for corrosion resistance. This helps in prolonging the lifespan of the components, especially in harsh environments.
- Zoning Ordinance
- Regulations set by local governments that can impact the design and installation of HVAC systems. These might include restrictions on equipment placement, noise levels, or efficiency requirements.
- Zinc Oxide
- A compound sometimes used in HVAC systems for corrosion protection, particularly in metal components exposed to harsh conditions or corrosive substances.