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Gas Boiler
Condensing boilers are water heaters typically used for heating systems that are fueled by gas or oil. When operated in the correct circumstances, a heating system can achieve high efficiency (greater than 90% on the higher heating value) by condensing water vapour found in the exhaust gases in a heat exchanger to preheat the circulating water. This recovers the latent heat of vaporisation, which would otherwise have been wasted. The condensate is sent to a drain. In many countries, the use of condensing boilers is compulsory or encouraged with financial incentives. For the condensation process to work properly, the return temperature of the circulating water must be around or below, so condensing boilers are often run at lower temperatures, around or below, which can require larger pipes and radiators than non-condensing boilers. Nevertheless, even partial condensing is more efficient than a conventional non-condensing boiler. Operational principle In a conventional boiler, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Higher Heating Value
The heating value (or energy value or calorific value) of a substance, usually a fuel or food (see food energy), is the amount of heat released during the combustion of a specified amount of it. The ''calorific value'' is the total energy released as heat when a substance undergoes complete combustion with oxygen under standard conditions. The chemical reaction is typically a hydrocarbon or other organic molecule reacting with oxygen to form carbon dioxide and water and release heat. It may be expressed with the quantities: * energy/ mole of fuel * energy/mass of fuel * energy/volume of the fuel There are two kinds of enthalpy of combustion, called high(er) and low(er) heat(ing) value, depending on how much the products are allowed to cool and whether compounds like are allowed to condense. The high heat values are conventionally measured with a bomb calorimeter. Low heat values are calculated from high heat value test data. They may also be calculated as the difference betwe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chartered Institution Of Building Services Engineers
The Chartered Institution of Building Services Engineers (CIBSE; pronounced 'sib-see') is an international professional engineering association based in London, England that represents building services engineers. It is a full member of the Construction Industry Council, and is consulted by government on matters relating to construction, engineering and sustainability. It is also licensed by the Engineering Council to assess candidates for inclusion on its Register of Professional Engineers. History CIBSE was formed in 1976, and received a Royal Charter that same year following a merger of the Institution of Heating and Ventilation Engineers (founded in 1897) and the Illuminating Engineering Society (founded in 1909). Previously CIBS, the word 'Engineers' was added in 1985, and hence the Institution became CIBSE. Royal Charter Under the CIBSE Royal Charter and By-laws, the Institution's primary objects are: * The promotion for the benefit of the public in general of the art, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OpenTherm
OpenTherm (OT) is a standard communications protocol used in central heating systems for the communication between central heating appliances and thermostatic controllers. As a standard, OpenTherm is independent of any single manufacturer. A controller from one manufacturer can in principle be used to control a boiler from another. However, OpenTherm controllers and boilers do not always work properly together. The OpenTherm standard comprises a number of optional features and some devices may include manufacturer-specific features. The presence or absence of such features may impair compatibility with other OpenTherm devices. History OpenTherm was founded in 1996 because multiple manufacturers needed a simple-to-use communicating system between room controller and boiler. It had to run, like the existing controllers, over the existing two wires, not polarity sensitive, without the use of batteries. For one British pound, Honeywell sold the first specification to the OpenTherm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Energy Efficiency In British Housing
Domestic housing in the United Kingdom presents a possible opportunity for achieving the 20% overall cut in UK greenhouse gas emissions targeted by the Government for 2010. However, the process of achieving that drop is proving problematic given the very wide range of age and condition of the UK housing stock. Carbon emissions Although carbon emissions from housing have remained fairly stable since 1990 (due to the increase in household energy use having been compensated for by the 'dash for gas'), housing accounted for around 30% of all the UK's carbon dioxide emissions in 2004 (40 million tonnes of carbon) up from 26.42% in 1990 as a proportion of the UK's total emissions. The Select Committee on Environmental Audit noted that emissions from housing could constitute over 55% of the UK's target for carbon emissions in 2050. A 2006 report commissioned by British Gas estimated the average carbon emissions for housing in each of the local authorities in Great Britain, the firs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminum
Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has a great affinity towards oxygen, passivation (chemistry), forming a protective layer of aluminium oxide, oxide on the surface when exposed to air. It visually resembles silver, both in its color and in its great ability to reflect light. It is soft, magnetism, nonmagnetic, and ductility, ductile. It has one stable isotope, 27Al, which is highly abundant, making aluminium the abundance of the chemical elements, 12th-most abundant element in the universe. The radioactive decay, radioactivity of aluminium-26, 26Al leads to it being used in radiometric dating. Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al3+ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acidic
An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen cation, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid. The first category of acids are the proton donors, or Brønsted–Lowry acids. In the special case of aqueous solutions, proton donors form the hydronium ion H3O+ and are known as Arrhenius acids. Brønsted and Lowry generalized the Arrhenius theory to include non-aqueous solvents. A Brønsted–Lowry or Arrhenius acid usually contains a hydrogen atom bonded to a chemical structure that is still energetically favorable after loss of H+. Aqueous Arrhenius acids have characteristic properties that provide a practical description of an acid. Acids form aqueous solutions with a sour taste, can turn blue litmus red, and react with bases and certain metals (like calcium) to form salts. The word ''acid'' is derived from the Latin , meaning 'sour'. An aqueous solution of an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientific Evidence
Scientific evidence is evidence that serves to either support or counter a scientific theory or hypothesis, although scientists also use evidence in other ways, such as when applying theories to practical problems. "Discussions about empirical evidence have tended to focus on epistemological questions regarding its role in theory testing ... even though empirical evidence also plays important and philosophically interesting roles in other areas including scientific discovery, the development of experimental tools and techniques, and the application of scientific theories to practical problems." Such evidence is expected to be empirical evidence and interpretable in accordance with the scientific method. Standards for scientific evidence vary according to the field of inquiry, but the strength of scientific evidence is generally based on the results of Statistics, statistical analysis and the strength of scientific controls. Principles of inference A person's assumptions or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buffering Agent
A buffer solution is a solution where the pH does not change significantly on dilution or if an acid or base is added at constant temperature. Its pH changes very little when a small amount of strong acid or base is added to it. Buffer solutions are used as a means of keeping pH at a nearly constant value in a wide variety of chemical applications. In nature, there are many living systems that use buffering for pH regulation. For example, the bicarbonate buffering system is used to regulate the pH of blood, and bicarbonate also acts as a buffer in the ocean. Principles of buffering Buffer solutions resist pH change because of a chemical equilibrium between the weak acid HA and its conjugate base A−: When some strong acid is added to an equilibrium mixture of the weak acid and its conjugate base, hydrogen ions (H+) are added, and the equilibrium is shifted to the left, in accordance with Le Chatelier's principle. Because of this, the hydrogen ion concentration increas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkaline
In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The adjective alkaline, and less often, alkalescent, is commonly used in English as a synonym for basic, especially for bases soluble in water. This broad use of the term is likely to have come about because alkalis were the first bases known to obey the Arrhenius definition of a base, and they are still among the most common bases. Etymology The word ''alkali'' is derived from Arabic ''al qalīy'' (or ''alkali''), meaning (see calcination), referring to the original source of alkaline substances. A water-extract of burned plant ashes, called potash and composed mostly of potassium carbonate, was mildly basic. After heating this substance with calcium hydroxide (''slaked lime''), a far more strongly basic substance known as ''caustic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Building Research Establishment
The Building Research Establishment (BRE) is a centre of building science in the United Kingdom, owned by charitable organisation the BRE Trust. It is a former Government of the United Kingdom, UK government national laboratory that was privatised in 1997. BRE provides research, advice, training, testing, certification and standards for both public sector, public and private sector organisations in the UK and abroad. It has its headquarters in Garston, Hertfordshire, England, with regional sites in Glasgow, Swansea, the US, India, the Middle East and China. BRE is funded with income from commissioned research, commercial programmes and by a number of digital tools for use in the construction sector. Programmes *BRE's certification arm, BRE Global, is an independent, third-party certification body responsible for sustainability certification schemes such as BREEAM (for buildings and communities), CEEQUAL (for infrastructure), the Home Quality Mark (for housing) and LPCB certific ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plumber
A plumber is a tradesperson who specializes in installing and maintaining systems used for potable (drinking) water, hot-water production, sewage and drainage in plumbing systems.Employment and Occupations in the Skilled Trades in Michigan , Michigan Department of Technology, Management, and Budget, Bureau of Labor Market Information and Strategic Initiatives (June 2013). History The origin of the word "plumber" dates from the . Roman roofs used lead in conduits and drain pipes and some were also covered with lead; lead was also used for[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embedded System
An embedded system is a specialized computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is embedded as part of a complete device often including electrical or electronic hardware and mechanical parts. Because an embedded system typically controls physical operations of the machine that it is embedded within, it often has real-time computing constraints. Embedded systems control many devices in common use. , it was estimated that ninety-eight percent of all microprocessors manufactured were used in embedded systems. Modern embedded systems are often based on microcontrollers (i.e. microprocessors with integrated memory and peripheral interfaces), but ordinary microprocessors (using external chips for memory and peripheral interface circuits) are also common, especially in more complex systems. In either case, the processor(s) us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
