 "All-air" and "air-water" HVAC systems use air ducts, outlets, and inlets installed throughout their buildings. The "outlet vent" is actually an "air outlet", or more specifically in this case an "air diffuser". HVAC (pronounced either "H-V-A-C" or, occasionally, "H-VAK") is an initialism/acronym that stands for "heating, ventilating, and air conditioning". This is sometimes referred to as climate control. In certain regions (e.g., UK) the term "Building Services" is also used, but may also include plumbing and electrical systems. Refrigeration is sometimes added to the field's abbreviation as HVAC&R or HVACR. Image File history File links Central_ventilation_tube2. ...
Image File history File links Central_ventilation_tube2. ...
A round duct connecting to a typical diffuser Ducts are used in heating, ventilation, and air conditioning (HVAC) to carry air - these include conditioned, fresh, stale, foul (toilet extract), and contaminated air (flue exhaust, fume extraction) - from place to place. ...
Acronyms and initialisms are abbreviations formed from the initial letter or letters of words, such as NATO and XHTML, and are pronounced in a way that is distinct from the full pronunciation of what the letters stand for. ...
It has been suggested that this article or section be merged with Backronym and Apronym (Discuss) Acronyms and initialisms are abbreviations, such as NATO, laser, and ABC, written as the initial letter or letters of words, and pronounced on the basis of this abbreviated written form. ...
Return inlet (left)Supply outlet (right). ...
Note: in the broadest sense, air conditioning can refer to any form of heating, ventilation, and air-conditioning. ...
It has been suggested that Refrigerator be merged into this article or section. ...
The HVAC industry is huge, worldwide, with career opportunities ranging from operation and maintenance, to system design and construction, to equipment manufacturing and sales, and to education and research. Annual sales are in the US$100's of billions. There are also hundreds of related local, national, and international professional, technical, trade, and labor organizations such as ASHRAE, SMACNA, ACCA, and AMCA, to name just a few, that support the industry and encourage high standards and achievement. The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) is an international voluntary organization for people involved in heating, ventilation, air conditioning, or refrigeration (HVAC&R). ...
The Sheet Metal and Air Conditioning Contractors National Association (SMACNA; pronounced Smack-Nah) is an international association of union HVAC contractors. ...
The Air Movement and Control Association International, Inc. ...
The three HVAC functions, heating, ventilating, and air-conditioning, are closely interrelated. All seek to provide thermal comfort, acceptable indoor air quality, and reasonable installation, operation, and maintenance costs. HVAC systems can provide ventilation, reduce infiltration, and maintain pressure relationships between spaces. How air is delivered to, and removed from spaces is known as room air distribution.[1] Human thermal comfort is the state of mind that expresses satisfaction with the surrounding environment, according to ASHRAE Standard 55. ...
Indoor Air Quality (IAQ) deals with the content of interior air that could affect health and comfort of building occupants. ...
Return inlet (left)Supply outlet (right). ...
Infiltration is the unintentional or accidential introduction of outside air into a building, typically through cracks in the building envelope and through use of doors for passage. ...
Characterizing how air is introduced to, flows through, and is removed from spaces is called room air distribution. ...
In modern buildings the design, installation, and control systems of these functions are integrated into one or more HVAC systems. For very small buildings, contractors normally "size" and select HVAC systems and equipment. For larger buildings where required by law, "building services" designers and engineers, such as mechanical, architectural, or building services engineers analyze, design, and specify the HVAC systems, and specialty mechanical contractors build and commission them. In all buildings, building permits for, and code-compliance inspections of the installations are the norm. A control system is a device or set of devices that manage the behavior of other devices. ...
Engineering is the application of scientific and technical knowledge to solve human problems. ...
Mechanical engineers design and build engines and power plants. ...
An architectural engineer applies the skills of many engineering disciplines to the design, construction, operation, maintenance, and renovation of buildings while paying attention to their impacts on the surrounding environment. ...
// Building engineering: a discipline for the modern era Building engineering, commonly known in the US as architectural engineering, is an emerging engineering discipline that concerns with the planning, design, construction, operation, renovation, and maintenance of buildings, as well as with their impacts on the surrounding environment. ...
Major Terms
- Air handler, or air handling unit (AHU) can mean a whole unit including the blower, heating and cooling elements, filter racks or chamber, dampers, humidifier, and other central equipment in direct contact with the airflow. This does not include the ductwork through the building.
- Makeup Air Unit (MAU) is an air handler that conditions 100% outside air. MAUs are typically used in industrial settings, or in once-through, low-flow, or primary-secondary commercial HVAC systems.
- Rooftop Unit (RTU) is an air handling unit, of recirculating or once-through design, that is for outdoor installation. They most often include, internally, their own heating and cooling devices. RTUs are very popular -- particularly for single-story commercial buildings.
- Fan Coil Unit (FCU) is a small terminal unit that is often composed of only a blower and either a heating or a cooling coil. Often used in hotels, condos, or apartments.
- Constant Air Volume (CAV) is an all-air or air-water HVAC system that has variable supply air temperature, but a constant flow rate of air. Most residential forced-air systems are small CAV systems with on/off control.
- Variable Air Volume (VAV) is an all-air or air-water HVAC system that has a relatively fixed supply air temperature, but the volumetric flow rate of air varies to meet the thermal load. Most new commercial buildings have VAV systems due to their reduced fan energy consumption, as compared to CAV.
- Thermal Zone is a single or group of neighboring indoor spaces that the HVAC designer or contractor expects will have similar thermal loads. Zones are defined to reduce the number of HVAC subsystems, and thus initial cost. Small residences typically have only one conditioned thermal zone, plus unconditioned spaces such as attached garages, attics, and crawlspaces. Basements may be either conditioned or unconditioned.
- Controllers are computers that can be programmed to execute functions such as turning on fans and opening dampers.
Anything that moves the air such as fans, blowers, etc. ...
Constant Air Volume (CAV) is a type of heating, ventilating, and air-conditioning (HVAC) system. ...
A variable air volume (VAV) device is a computer-controlled zone damper used in HVAC systems to vary the flow of air through ductwork. ...
Heating Heating systems may be classified as central or local. Central heating is often used in cold climates to heat private houses and public buildings. Such a system contains a boiler, furnace, or heat pump to heat water, steam, or air, all in a central location such as a furnace room in a home or a mechanical room in a large building. The system also contains piping or ductwork to distribute the heated fluid, and radiators to transfer this heat to the air. The term radiator in this context is misleading since most heat transfer from the heat exchanger is by convection, not radiation. The radiators may be mounted on walls or buried in the floor to give under-floor heating. For the Grand Central Records albums, see Central Heating (Grand Central album) and Central Heating 2. ...
For the Grand Central Records albums, see Central Heating (Grand Central album) and Central Heating 2. ...
A boiler is a closed vessel in which water or other fluid is heated under pressure. ...
A furnace is a device for heating air or any other fluid. ...
A diagram of a simple heat pumps vapor-compression refrigeration cycle: 1) condenser, 2) expansion valve, 3) evaporator, 4) compressor. ...
Furnace room A Furnace room is a room for locating the furnace and auxillary equipment. ...
Mechanical room in a large office building. ...
Radiators and convectors are types of heat exchangers designed to transfer thermal energy from one medium to another for the purpose of cooling and heating. ...
Convection is the internal movement of currents within fluids (i. ...
Thermal radiation is electromagnetic radiation emitted from the surface of an object which is due to the objects temperature. ...
All but the simplest systems have a pump to circulate the water and ensure an equal supply of heat to all the radiators. The heated water is often fed through another heat exchanger inside a storage cylinder to provide hot running water.
Forced air systems send air through ductwork. During warm weather the same ductwork can be reused for air conditioning. The forced air can be filtered or put through air cleaners. Most ducts cannot fit a human being (as they do in many films) since this would require a greater duct-structural integrity and create a potential security liability. A round duct connecting to a typical diffuser Ducts are used in heating, ventilation, and air conditioning (HVAC) to carry air - these include conditioned, fresh, stale, foul (toilet extract), and contaminated air (flue exhaust, fume extraction) - from place to place. ...
The heating elements (radiators or vents) should be located in the coldest part of the room and typically next to the windows to minimize condensation. Popular retail devices that direct vents away from windows to prevent "wasted" heat defeat this design parameter. Drafts contribute more to the subjective feeling of coldness than actual room temperature. Therefore, rather than improving the heating of a room/building, it is often more important to control the air leaks.
The invention of central heating is often credited to the ancient Romans, who installed a system of air ducts in walls and floors of public baths and private villas. The ducts were fed with hot air from a central fire. Generally, these heated by radiation; a better physiologic approach to heating than conventional forced air convective heating. The Roman Empire is the name given to both the imperial domain developed by the city-state of Rome and also the corresponding phase of that civilization, characterized by an autocratic form of government. ...
Ruins of the hypocaust under the floor of a Roman villa. ...
Ventilation Ventilation is the changing of air in any space to remove moisture, odors, smoke, heat, and airborne bacteria. Ventilation includes both the exchange of air to the outside as well as circulation of air within the building. It is one of the most important factors for maintaining acceptable indoor air quality in buildings. Methods for ventilating a building may be divided into mechanical/forced and natural types.[2] Return inlet (left)Supply outlet (right). ...
Indoor Air Quality (IAQ) deals with the content of interior air that could affect health and comfort of building occupants. ...
Mechanical or Forced ventilation "Mechanical" or "Forced" ventilation is used to control indoor air quality. Excess humidity, odors, and contaminants can often be controlled via dilution or replacement with outside air. But in humid climates, much energy is required to remove excess moisture from ventilation air. Indoor Air Quality (IAQ) deals with the content of interior air that could affect health and comfort of building occupants. ...
Humidity is the concentration of water vapor in the air. ...
Kitchens and bathrooms typically have mechanical exhaust to control odors and sometimes humidity. Factors in the design of such systems include the flow rate (which is a function of the fan speed and exhaust vent size) and noise level. If the ducting for the fans traverse unheated space (e.g., an attic), the ducting should be insulated as well to prevent condensation on the ducting. Direct drive fans are available for many applications, and can reduce maintenance needs.
Heat recovery ventilation systems employ heat exchangers to recover some heat from exhausted air to preheat the incoming outside air. Heat recovery ventilation is a ventilation system that employs a heat exchanger between the inbound and outbound air flow to save on energy required for heating (or cooling) the room. ...
Ceiling fans and table/floor fans are very effective in circulating air within a room. Paradoxically, because hot air rises, ceiling fans may be used to keep a room warmer. Ceiling fans do not provide 'ventilation', however. Non-electric fan Household Electric Fan A fan is a device used to induce airflow and generally made from broad, flat surfaces which revolve or oscillate. ...
Natural ventilation Natural ventilation is the ventilation of a building with outside air without the use of a fan or other mechanical system. It can be achieved with operable windows when the spaces to ventilate are small and the architecture permits. In more complex systems warm air in the building can be allowed to rise and flow out upper openings to the outside (stack effect) thus forcing cool outside air to be drawn into the building naturally though openings in the lower areas. These systems use very little energy but care must be taken to ensure the occupants' comfort. In warm or humid months, in many climates, maintaining thermal comfort via solely natural ventilation may not be possible so conventional air conditioning systems are used as backups. Natural ventilation is the process of supplying and removing air through an indoor space by natural means. ...
Stack effect is the ventilation in buildings and chimneys that results from thermal differences between indoor and outside temperature. ...
Human thermal comfort is the state of mind that expresses satisfaction with the surrounding environment, according to ASHRAE Standard 55. ...
Note: in the broadest sense, air conditioning can refer to any form of heating, ventilation, and air-conditioning. ...
Air-conditioning An air conditioning system, or a stand-alone air conditioner, provides heating, cooling, ventilation, and humidity control for all or part of a building. 'Central', 'all-air' air conditioning systems are often installed in modern residences, offices, and public buildings, but are difficult to retrofit (install in a building that was not designed to receive it) because of the bulky air ducts required. A duct system must be carefully maintained to prevent the growth of pathogenic bacteria in the ducts. An alternative to large ducts to carry the needed air to heat or cool an area is the use of remote fan coils or split systems. These systems, although most often seen in residential applications, are gaining popularity in small commercial buildings. The remote coil is connected to a remote condenser unit using piping instead of ducts. Note: in the broadest sense, air conditioning can refer to any form of heating, ventilation, and air-conditioning. ...
Note: in the broadest sense, air conditioning can refer to any form of heating, ventilation, and air-conditioning. ...
A pathogen or infectious agent is a biological agent that causes disease or illness to its host. ...
Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ...
A dehumidifier is an air-conditioner-like device that controls the humidity of a room or building. They are often employed in basements which have a higher relative humidity because of their lower temperature (and propensity for damp floors and walls). In food retailing establishments, large open chiller cabinets are highly effective at dehumidifying the internal air. Conversely, a humidifier increases the humidity of a building. A dehumidifier is a household appliance that reduces the level of humidity in a room. ...
This article does not cite its references or sources. ...
A humidifier is a household appliance that increases the level of water vapor, or moisture, in a room. ...
Air-conditioned buildings often have sealed windows, because open windows would disrupt the attempts of the HVAC system to maintain constant indoor air conditions.
HVAC Energy Efficiency
Heating Energy Water heating is more efficient for heating buildings and was the standard many years ago. Today forced air systems can double for air conditioning and are more popular. The most efficient central heating method is geothermal heating. Geothermal heating is a method of heating and cooling a building. ...
Energy efficiency can be improved even more in central heating systems by introducing zoned heating. This allows a more granular application of heat, similar to non-central heating systems. Zones are controlled by multiple thermostats. In water heating systems the thermostats control zone valves, and in forced air systems they control zone dampers inside the vents which selectively block the flow of air. A thermostat is a device for maintaining the temperature of a system within a range by controlling the flow of heat energy into or out of the system. ...
A zone valve is a specific type of valve used to control the flow of water or steam in a hydronic heating or cooling system. ...
A zone damper is a specific type of damper used to control the flow of air in an HVAC heating or cooling system. ...
Air Conditioning Energy The performance of vapor compression refrigeration cycles is limited by thermodynamics. These AC and heat pump devices move heat rather than convert it from one form to another, so thermal efficiencies do not appropriately describe their performance. The Coefficient-of-Performance (COP) does, but this dimensionless measure does not enjoy wide use like the dimensional Energy Efficiency Ratio (EER). To more accurately describe the performance of air conditioning equipment over a typical cooling season a modified version of the EER is used, and is the Seasonal Energy Efficiency Ratio (SEER). The SEER article describes it further, and presents some economic comparisons using this useful performance measure. Thermodynamics (from the Greek thermos meaning heat and dynamics meaning power) is a branch of physics that studies the effects of changes in temperature, pressure, and volume on physical systems at the macroscopic scale by analyzing the collective motion of their particles using statistics. ...
A diagram of a simple heat pumps vapor-compression refrigeration cycle: 1) condenser, 2) expansion valve, 3) evaporator, 4) compressor. ...
The thermal efficiency () is a dimensionless performance measure of a thermal device such as an internal combustion engine, a boiler, or a furnace, for example. ...
Seer has several possible meanings: A fortune teller or prophet The fictional character on the television series Charmed The Seasonal energy efficiency ratio standard for air conditioning appliances This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...
HVAC Industry in the United Kingdom NOTE: The information in this section applies only to the United Kingdom
Building Services is a construction body that covers the essential services that allow buildings to operate. It includes the electrotechnical, heating, ventilating, air conditioning, refrigeration and plumbing industries. For other uses, see Building (disambiguation). ...
Cranes are essential in large construction projects, such as this skyscraper In project architecture and civil engineering, construction is the building or assembly of any infrastructure on a site. ...
Services are: plural of service Tertiary sector of industry IRC services Web services the name of a first-class cricket team in India This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...
HVAC may also stand for High-voltage alternating current HVAC is an initialism that stands for heating, ventilation and air-conditioning. This is sometimes referred to as climate control. ...
Ventilation is movement of air, and can be used in the following contexts: ventilation (architecture) ventilation (firefighting) ventilation (physiology) This is a disambiguation page: a list of articles associated with the same title. ...
Note: in the broadest sense, air conditioning can refer to any form of heating, ventilation, and air-conditioning. ...
It has been suggested that Refrigerator be merged into this article or section. ...
A plumber wrench for working on pipes and fittings Plumbing, from the Latin for lead (plumbum), is the skilled trade of working with pipes, tubing and plumbing fixtures for potable water systems and the drainage of waste. ...
Building Services is part of a sector that has over 51,000 businesses and employs over 500,000 people. This sector has an annual turnover of £19.3 billion which represents 2%-3% of the GDP. A sector is a part of a whole. ...
Within the construction sector, it is the job of the building services engineer to design, install and maintain the essential services such as gas, electricity, water, heating and lighting, as well as many others. These all help to make buildings comfortable and healthy places to live and work in. Cranes are essential in large construction projects, such as this skyscraper In project architecture and civil engineering, construction is the building or assembly of any infrastructure on a site. ...
Design, usually considered in the context of the applied arts, engineering, architecture, and other such creative endeavours, is used as both a noun and a verb. ...
Installation can be used to refer to Installation (computer programs) of an operating system or program. ...
Lightning strikes during a night-time thunderstorm. ...
Lighting refers to either artificial light sources such as lamps or to natural illumination of interiors from daylight. ...
To train as a building services engineer, the academic requirement is GCSEs (A-C) / Standard Grades (1-3) in Maths and Science, which are important in measurements, planning and theory. Employers will often want a degree in a branch of engineering, such as building environment engineering, electrical engineering or mechanical engineering. A typical North American steam train In rail transport, a train consists of rail vehicles that move along guides to transport freight or passengers from one place to another. ...
Plato is credited with the inception of academia: the body of knowledge, its development and transmission across generations. ...
It has been suggested that Professional degree be merged into this article or section. ...
Engineering is the application of scientific or mathematical principles with due reference to economics, society and environment to develop solutions to technical problems, creating products, facilities, and structures that are useful to people. ...
HVAC Equipment Note: in the broadest sense, air conditioning can refer to any form of heating, ventilation, and air-conditioning. ...
It has been suggested that this article or section be merged with air cleaner. ...
Anything that moves the air such as fans, blowers, etc. ...
A boiler is a closed vessel in which water or other fluid is heated under pressure. ...
York International water-cooled chiller. ...
Image 1: Natural draft wet cooling towers at Didcot Power Station, UK Cooling towers are evaporative coolers used for cooling water or other working medium to near the ambient wet-bulb air temperature. ...
Damper is a traditional Australian outback food prepared by swagmen, drovers and other travellers. ...
A diffuser is the mechanical device that is designed to control the characteristics of a fluid at the entrance to a thermodynamic open system. ...
A duct may refer to: An atmospheric duct. ...
Evaporative coolers (also called air coolers or desert coolers) are cooling devices which uses simple evaporation of water in air. ...
Non-electric fan Household Electric Fan A fan is a device used to induce airflow and generally made from broad, flat surfaces which revolve or oscillate. ...
BMWs distinctive kidney-shaped grille on an E34 M5 Audis single frame grille, here on a second generation TT Grille is also the name of a German self-propelled artillery vehicle. ...
A heat exchanger is a device built for efficient heat transfer from one fluid to another, whether the fluids are separated by a solid wall so that they never mix, or the fluids are directly contacted. ...
A humidifier is a household appliance that increases the level of water vapor, or moisture, in a room. ...
A dehumidifier is a household appliance that reduces the level of humidity in a room. ...
A HVAC control system is a computerized system for climate control in buildings. ...
Piping is used to convey fluids (usually liquids and gases but sometimes loose solids) from one location to another. ...
An electrically driven pump (electropump) for waterworks near the Hengsteysee, Germany. ...
See also The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) is an international voluntary organization for people involved in heating, ventilation, air conditioning, or refrigeration (HVAC&R). ...
An architectural engineer applies the skills of many engineering disciplines to the design, construction, operation, maintenance, and renovation of buildings while paying attention to their impacts on the surrounding environment. ...
// Building engineering: a discipline for the modern era Building engineering, commonly known in the US as architectural engineering, is an emerging engineering discipline that concerns with the planning, design, construction, operation, renovation, and maintenance of buildings, as well as with their impacts on the surrounding environment. ...
Building indoor environment covers the environmental aspects in the design, analysis, and operation of energy-efficient, healthy, and comfortable buildings. ...
The Chartered Institute of Building Services Engineers (CIBSE) represents building services engineers and their various specialities. ...
BACnet is a Data Communications Protocol for Building Automation and Control Networks. ...
LonWorks is a networking platform specifically created to address the unique performance, reliability, installation, and maintenance needs of control applications. ...
Mechanical engineers design and build engines and power plants. ...
It has been suggested that Refrigerator be merged into this article or section. ...
Solar power describes a number of methods of harnessing energy from the light of the sun. ...
Underfloor heating is a unique traditional form of central heating that is gaining newfound popularity. ...
References - ^ Designer's Guide to Ceiling-Based Air Diffusion, Rock and Zhu, ASHRAE, Inc., Atlanta, GA, USA, 2002
- ^ Ventilation and Infiltration chapter, Fundamentals volume of the ASHRAE Handbook, ASHRAE, Inc., Atlanta, GA, 2005
The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) is an international voluntary organization for people involved in heating, ventilation, air conditioning, or refrigeration (HVAC&R). ...
External links - Complete HVAC Visual Training
- The UK Selfbuild FAQ
- The effects of displacement ventilation
- Natural Ventilation - by Andy Walker of the National Renewable Energy Laboratory
- IEA Energy Conservation in Buildings and Community Systems Programme.
- BTU Calculator A worksheet by the Association of Home Appliance Manufacturers to help you estimate how much cooling capacity you need.
- Indoor Environmental Quality
- HVAC Schematics
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