text:
Water heating

[[File:Active Indirect Water Heater Diagram.svg|thumb|upright=1.3|1. Municipal water feed

2. Fluid from water storage tank to external (passive) heat source; passive heat source can be the ground (soil or groundwater), sun or air via heat pump, district heating or thermodynamic solar panel

3. Fluid from heat pump, or thermodynamic solar panel to water storage tank

4. Pump, actuator, controller and other parts

5. Water heater

6. Water storage tank

7. Hot water to domestic appliances]] Water heating is a heat transfer process that uses an energy source to heat water above its initial temperature. Typical domestic uses of hot water include cooking, cleaning, bathing, and space heating. In industry, hot water and water heated to steam have many uses.

Domestically, water is traditionally heated in vessels known as water heaters, kettles, cauldrons, pots, or coppers. These metal vessels that heat a batch of water do not produce a continual supply of heated water at a preset temperature. Rarely, hot water occurs naturally, usually from natural hot springs. The temperature varies with the consumption rate, becoming cooler as flow increases.

Appliances that provide a continual supply of hot water are called water heaters, hot water heaters, hot water tanks, boilers, heat exchangers, geysers (Southern Africa and the Arab world), or calorifiers. These names depend on region, and whether they heat potable or non-potable water, are in domestic or industrial use, and their energy source. In domestic installations, potable water heated for uses other than space heating is also called domestic hot water (DHW).

Fossil fuels (natural gas, liquefied petroleum gas, oil), or solid fuels are commonly used for heating water. These may be consumed directly or may produce electricity that, in turn, heats water. Electricity to heat water may also come from any other electrical source, such as nuclear power or renewable energy. Alternative energy such as solar energy, heat pumps, hot water heat recycling, and geothermal heating can also heat water, often in combination with backup systems powered by fossil fuels or electricity.

Densely populated urban areas of some countries provide district heating of hot water. This is especially the case in Scandinavia, Finland and Poland. District heating systems supply energy for water heating and space heating from combined heat and power (CHP) plants such as incinerators, central heat pumps, waste heat from industries, geothermal heating, and central solar heating. Actual heating of tap water is performed in heat exchangers at the consumers' premises. Generally the consumer has no in-building backup system as redundancy is usually significant on the district heating supply side.

Today, in the United States, domestic hot water used in homes is most commonly heated with natural gas, electric resistance, or a heat pump. Electric heat pump water heaters are significantly more efficient than electric resistance water heaters, but also more expensive to purchase. Some energy utilities offer their customers funding to help offset the higher first cost of energy efficient water heaters.

Types of water heating appliances
Hot water used for space heating may be heated by fossil fuels in a boiler, while potable water may be heated in a separate appliance. This is common practice in the US, especially when warm-air space heating is usually employed.

Storage water heaters (tank-type)

In household and commercial usage, most North American and Southern Asian water heaters are the tank type, also called storage water heaters. These consist of a cylindrical vessel or container that keeps water continuously hot and ready to use. Typical sizes for household use range from 75–400 L (20–100 US gallons). These may use electricity, natural gas, propane, heating oil, solar, or other energy sources. Natural gas heaters are most popular in the US and most European countries, since the gas is often conveniently piped throughout cities and towns and currently is the cheapest to use. In the United States, typical natural gas water heaters for households without unusual needs are 40 – with a burner rated at 34,000 –.

This is a popular arrangement where higher flow rates are required for limited periods. Water is heated in a pressure vessel that can withstand a hydrostatic pressure close to that of the incoming mains supply. A pressure reducing valve is sometimes employed to limit the pressure to a safe level for the vessel. In North America, these vessels are called hot water tanks, and may incorporate an electrical resistance heater, a heat pump, or a gas or oil burner that heats water directly.

Where hot-water space heating boilers are installed, domestic hot water cylinders are usually heated indirectly by primary water from the boiler, or by an electric immersion heater (often as backup to the boiler). In the UK these vessels are called indirect cylinders and direct cylinders, respectively. Additionally, if these cylinders form part of a sealed system, providing mains-pressure hot water, they are known as unvented cylinders. In the US, when connected to a boiler, they are called indirect-fired water heaters.

Compared to tankless heaters, storage water heaters have the advantage of using energy (gas or electricity) at a relatively slow rate, storing the heat for later use. The disadvantage is that over time, heat escapes through the tank wall and the water cools down, activating the heating system to heat the water back up, so investing in a tank with better insulation improves this standby efficiency. Additionally, when heavy use exhausts the hot water, there is a significant delay before hot water is available again. Larger tanks tend to provide hot water with less temperature fluctuation at moderate flow rates.

Volume storage water heaters in the United States and New Zealand are typically vertical cylindrical tanks, usually standing on the floor, a 'cylinder tray' or on a platform raised a short distance above the floor. Volume storage water heaters in Spain are typically horizontal. In India, they are mainly vertical. In apartments they can be mounted in the ceiling space over laundry-utility rooms. In Australia, gas and electric outdoor tank heaters have mainly been used (with high temperatures to increase effective capacity), but solar roof tanks are becoming fashionable.

Tiny point-of-use (POU) electric storage water heaters with capacities ranging from 8–32 L (2–6 gallons) are made for installation in kitchen and bath cabinets or on the wall above a sink. They typically use low power heating elements, about 1 kW to 1.5 kW, and can provide hot water long enough for hand washing, or, if plumbed into an existing hot water line, until hot water arrives from a remote high capacity water heater. They may be used when retrofitting a building with hot water plumbing is too costly or impractical. Since they maintain water temperature thermostatically, they can only supply a continuous flow of hot water at extremely low flow rates, unlike high-capacity tankless heaters.

In tropical countries like Singapore and India, a storage water heater may vary from 10 L to 35 L. Smaller water heaters are sufficient, as ambient weather temperatures and incoming water temperature are moderate. The Coldest regions in India like Kashmir, people are mostly dependent on the storage type electric water heaters. Mostly 50L or 75L Storage type electric water heaters are connected to overhead water source.

Point-of-use (POU) vs centralized hot water
A locational design decision may be made between point-of-use and centralized water heaters. Centralized water heaters are more traditional, and are still a good choice for small buildings. For larger buildings with intermittent or occasional hot water use, multiple POU water heaters may be a better choice, since they can reduce long waits for hot water to arrive from a remote heater. The decision where to locate the water heater(s) is only partially independent of the decision of a tanked vs. tankless water heater, or the choice of energy source for the heat.

Instantaneous water heaters (tankless-type)

Tankless water heaters—also called instantaneous, continuous flow, inline, flash, on-demand, or instant-on water heaters—are gaining in popularity. These high-power water heaters instantly heat water as it flows through the device, and do not retain any water internally except for what is in the heat exchanger coil. Copper heat exchangers are preferred in these units because of their high thermal conductivity and ease of fabrication.

Tankless heaters may be installed throughout a household at more than one point-of-use (POU), far from a central water heater, or larger centralized models may still be used to provide all the hot water requirements for an entire house. The main advantages of tankless water heaters are a plentiful continuous flow of hot water (as compared to a limited flow of continuously heated hot water from conventional tank water heaters), and potential energy savings under some conditions. The main disadvantage is their much higher initial costs; a US study in Minnesota reported a 20- to 40-year payback for the tankless water heaters. In a comparison to a less efficient natural gas fired hot water tank, on-demand natural gas will cost 30% more over its useful life.

Stand-alone appliances for quickly heating water for domestic usage are known in North America as tankless or on demand water heaters. In some places, they are called multipoint heaters, geysers or ascots. In Australia and New Zealand they are called instantaneous hot water units. In Argentina they are called calefones. In that country calefones use gas instead of electricity, although gas powered tankless water heaters can also be found in other countries. A similar wood-fired appliance was known as the chip heater.

A common arrangement where hot-water space heating is employed is for a boiler also to heat potable water, providing a continuous supply of hot water without extra equipment. Appliances that can supply both space-heating and domestic hot water are called combination (or combi) boilers. Though on-demand heaters provide a continuous supply of domestic hot water, the rate at which they can produce it is limited by the thermodynamics of heating water from the available fuel supplies.

Electric shower heads
An electric shower head has an electric heating element which heats water as it passes through. These self-heating shower heads are specialized point-of-use (POU) tankless water heaters, and are widely used in some countries.

Invented in Brazil in the 1930s due to a lack of central gas distribution and used frequently since the 1940s, the electric shower is a home appliance often seen in South and Central American countries due to the higher costs of gas distribution, combined with households that in most cases do not support conventional water heaters. Earlier models were made of chromed copper or brass, which were expensive, but since 1970, units made of injected plastics are popular due to low prices similar to that of a hair dryer.

Electric showers have a simple electric system, working like a coffee maker, but with a larger water flow. A flow switch turns on the device when water flows through it. Once the water is stopped, the device turns off automatically. An ordinary electric shower often but not always has three heat settings: high (5.5 kW), low (2.5 kW), or cold (0 W) to use when a central heater system is available or in hot seasons. Higher power (up to 7.5 KW) and lower power (up to 3.2 KW) versions are also made, as well as versions with 4 heat settings or a variable heat setting.

Energy usage
The power consumption of electric showers in the max. heating setting is about 5.5 kW for 120 V and 7.5 kW for 220 V. The lower costs with electric showers compared to the higher costs with tank boilers is due to the time of use: an electric shower uses energy only while the water flows, while a tank boiler works many times a day to keep a quantity of standing water hot for use throughout the day and night. Moreover, the transfer of electric energy to the water in an electric shower head is very efficient, approaching 100%. Electric showers may save energy compared to electric tank heaters, which lose some standby heat.

Safety
There is a wide range of electric shower heads, with various designs and types of heating controls. The heating element of an electric shower is immersed in the water stream, using an often replaceable nichrome resistive heating element which is often not sheathed and electrically isolated, in which case isolation is provided by earthing electrodes that directly touch the water before it exits the head. Electric shower heads with sheathed and electrically isolated heating elements are often marketed as such (chuveiros blindados in Portuguese) and are more expensive. Due to electrical safety standards as well as cost, modern electric showers are made of plastic instead of using metallic casings like in the past.

As an electrical appliance that uses more electric current than a clothes washer or a hair dryer, an electric shower installation requires careful planning, and generally is intended to be wired directly from the electrical distribution box with a dedicated circuit breaker and ground system. A poorly installed system with old aluminum wires, bad connections or an unconnected ground wire (which is often the case) may be dangerous, as the wires can overheat or electric current may leak via the water stream through the body of the user to earth.

Solar water heaters

Increasingly, solar powered water heaters are being used. Their solar collectors are installed outside dwellings, typically on the roof or walls or nearby, and the potable hot water storage tank is typically a pre-existing or new conventional water heater, or a water heater specifically designed for solar thermal. In Cyprus and Israel 90 percent of homes have solar water heating systems.

The most basic solar thermal models are the direct-gain type, in which the potable water is directly sent into the collector. Many such systems are said to use integrated collector storage (ICS), as direct-gain systems typically have storage integrated within the collector. Heating water directly is inherently more efficient than heating it indirectly via heat exchangers, but such systems offer very limited freeze protection (if any), can easily heat water to temperatures unsafe for domestic use, and ICS systems suffer from severe heat loss on cold nights and cold, cloudy days.

By contrast, indirect or closed-loop systems do not allow potable water through the panels, but rather pump a heat transfer fluid (either water or a water/antifreeze mix) through the panels. After collecting heat in the panels, the heat transfer fluid flows through a heat exchanger, transferring its heat to the potable hot water. When the panels are cooler than the storage tank or when the storage tank has already reached its maximum temperature, the controller in closed-loop systems stops the circulation pumps. In a drainback system, the water drains into a storage tank contained in conditioned or semi-conditioned space, protected from freezing temperatures. With antifreeze systems, however, the pump must be run if the panel temperature gets too hot (to prevent degradation of the antifreeze) or too cold (to prevent the water/antifreeze mixture from freezing.)

Flat panel collectors are typically used in closed-loop systems. Flat panels, which often resemble skylights, are the most durable type of collector, and they also have the best performance for systems designed for temperatures within 100 F-change of ambient temperature. Flat panels are regularly used in both pure water and antifreeze systems.

Another type of solar collector is the evacuated tube collector, which are intended for cold climates that do not experience severe hail and/or applications where high temperatures are needed (i.e., over 94 C). Placed in a rack, evacuated tube collectors form a row of glass tubes, each containing absorption fins attached to a central heat-conducting rod (copper or condensation-driven). The evacuated description refers to the vacuum created in the glass tubes during the manufacturing process, which results in very low heat loss and lets evacuated tube systems achieve extreme temperatures, far in excess of water's boiling point.

Geothermal heating
In countries like Iceland and New Zealand, and other volcanic regions, water heating may be done using geothermal heating, rather than combustion.

Gravity-fed system
Where a space-heating water boiler is employed, the traditional arrangement in the UK and Ireland is to use boiler-heated (primary) water to heat potable (secondary) water contained in a cylindrical vessel (usually made of copper)—which is supplied from a cold water storage vessel or container, usually in the roof space of the building. This produces a fairly steady supply of DHW (domestic hot water) at low static pressure head but usually with a good flow. In most other parts of the world, water heating appliances do not use a cold water storage vessel or container, but heat water at pressures close to that of the incoming mains water supply.

Other improvements
Other improvements to water heaters include check valve devices at their inlet and outlet, cycle timers, electronic ignition in the case of fuel-using models, sealed air intake systems in the case of fuel-using models, and pipe insulation. The sealed air-intake system types are sometimes called "band-joist" intake units. "High-efficiency" condensing units can convert up to 98% of the energy in the fuel to heating the water. The exhaust gases of combustion are cooled and are mechanically ventilated either through the roof or through an exterior wall. At high combustion efficiencies a drain must be supplied to handle the water condensed out of the combustion products, which are primarily carbon dioxide and water vapor.

In traditional plumbing in the UK, the space-heating boiler is set up to heat a separate hot water cylinder or water heater for potable hot water. Such water heaters are often fitted with an auxiliary electrical immersion heater for use if the boiler is out of action for a time. Heat from the space-heating boiler is transferred to the water heater vessel/container by means of a heat exchanger, and the boiler operates at a higher temperature than the potable hot water supply. Most potable water heaters in North America are completely separate from the space heating units, due to the popularity of HVAC/forced air systems in North America.

Residential combustion water heaters manufactured since 2003 in the United States have been redesigned to resist ignition of flammable vapors and incorporate a thermal cutoff switch, per ANSI Z21.10.1. The first feature attempts to prevent vapors from flammable liquids and gases in the vicinity of the heater from being ignited and thus causing a house fire or explosion. The second feature prevents tank overheating due to unusual combustion conditions. These safety requirements were made in response to homeowners storing, or spilling, gasoline or other flammable liquids near their water heaters and causing fires. Since most of the new designs incorporate some type of flame arrestor screen, they require monitoring to make sure they do not become clogged with lint or dust, reducing the availability of air for combustion. If the flame arrestor becomes clogged, the thermal cutoff may act to shut down the heater.

A wetback stove (NZ), wetback heater (NZ), or back boiler (UK), is a simple household secondary water heater using incidental heat. It typically consists of a hot water pipe running behind a fireplace or stove (rather than hot water storage), and has no facility to limit the heating. Modern wetbacks may run the pipe in a more sophisticated design to assist heat-exchange. These designs are being forced out by government efficiency regulations that do not count the energy used to heat water as 'efficiently' used.

History
Another type of water heater developed in Europe predated the storage model. In London, England, in 1868, a painter named Benjamin Waddy Maughan invented the first instantaneous domestic water heater that did not use solid fuel. Named the geyser after an Icelandic gushing hot spring, Maughan's invention made cold water at the top flow through pipes that were heated by hot gases from a burner at the bottom. Hot water then flowed into a sink or tub. The invention was somewhat dangerous because there was no flue to remove heated gases from the bathroom. A water heater is still sometimes called a geyser in the UK.

Maughn's invention influenced the work of a Norwegian mechanical engineer named Edwin Ruud. The first automatic, storage tank-type gas water heater was invented around 1889 by Ruud after he immigrated to Pittsburgh, Pennsylvania (US). The Ruud Manufacturing Company, still in existence today, made many advancements in tank-type and tankless water heater design and operation.

Thermodynamics and economics
Water typically enters residences in the US at about 10 C, depending on latitude and season. Hot water temperatures of 50 °C are usual for dish-washing, laundry and showering, which requires that the heater raise the water temperature about 40 C-change if the hot water is mixed with cold water at the point of use. The Uniform Plumbing Code reference shower flow rate is 2.5 USgal per minute. Sink and dishwasher usages range from 1 - 3 USgal per minute.

Natural gas is often measured by volume or heat content. Common units of measurement by volume are cubic metre or cubic feet at standard conditions or by heat content in kilowatt hours, British thermal units (BTU) or therm, which is equal to 100,000 BTU. A BTU is the energy required to raise one pound of water by one degree Fahrenheit. A US gallon of water weighs 8.3 lbs. To raise 60 usgal of water from 10 °C to 50 °C at 90% efficiency requires $60 × 8.3 × (122 − 50) × 1.11 = 39,840 BTU$. A 157,000 BTU/h heater, as might exist in a tankless heater, would take about 15 minutes to do this. At $1 per therm, the cost of the gas would be about 40 cents. In comparison, a typical 60 usgal tank electric water heater has a 4.5 kW heating element, which at 100% efficient results in a heating time of about 2.34 hours. At $0.16/kWh the electricity would cost $1.68.

Energy efficiencies of water heaters in residential use can vary greatly, particularly depending on manufacturer and model. However, electric heaters tend to be slightly more efficient (not counting power station losses) with recovery efficiency (how efficiently energy transfers to the water) reaching about 98%. Gas-fired heaters have maximum recovery efficiencies of only about 82–94% (the remaining heat is lost with the flue gasses). Overall energy factors can be as low as 80% for electric and 50% for gas systems. Natural gas and propane tank water heaters with energy factors of 62% or greater, as well as electric tank water heaters with energy factors of 93% or greater, are considered high-efficiency units. Energy Star-qualified natural gas and propane tank water heaters (as of September 2010) have energy factors of 67% or higher, which is usually achieved using an intermittent pilot together with an automatic flue damper, baffle blowers, or power venting.

Direct electric resistance tank water heaters are not included in the Energy Star program; however, the Energy Star program does include electric heat pump units with energy factors of 200% or higher. Tankless gas water heaters (as of 2015) must have an energy factor of 90% or higher for Energy Star qualification. Since electricity production in thermal plants has efficiency levels ranging from only 15% to slightly over 55% (combined cycle gas turbine), with around 40% typical for thermal power stations, direct resistance electric water heating may be the least energy efficient option.

However, use of a heat pump can make electric water heaters much more energy efficient and lead to a decrease in carbon dioxide emissions, even more so if a low carbon source of electricity is used. Using district heating utilizing waste heat from electricity generation and other industries to heat residences and hot water gives an increased overall efficiency, removing the need for burning fossil fuel or using high energy value electricity to produce heat in the individual home.

Fundamentally, it takes a great deal of energy to heat water, as one may experience when waiting to boil a gallon of water on a stove. For this reason, tankless on-demand water heaters require a powerful energy source. A standard 120V, 15-ampere rated wall electric outlet, by comparison, only sources enough power to warm a disappointingly small amount of water: about 0.17 USgal per minute at 40 C-change temperature elevation.

The energy used by an electric water heater can be reduced by as much as 18% through optimal schedule and temperature control that is based on knowledge of the usage pattern.

US minimum requirements
On April 16, 2015, as part of the National Appliance Energy Conservation Act (NAECA), new minimum standards for efficiency of residential water heaters set by the United States Department of Energy went into effect. All new gas storage tank water heaters with capacities smaller than 55 USgal sold in the United States in 2015 or later shall have an energy factor of at least 60% (for 50-US-gallon units, higher for smaller units), increased from the pre-2015 minimum standard of 58% energy factor for 50-US-gallon gas units. Electric storage tank water heaters with capacities less than 55 US gallons sold in the United States shall have an energy factor of at least 95%, increased from the pre-2015 minimum standard of 90% for 50-US-gallon electric units.

Under the 2015 standard, for the first time, storage water heaters with capacities of 55 US gallons or larger now face stricter efficiency requirements than those of 50 US gallons or less. Under the pre-2015 standard, a 75 USgal gas storage water heater with a nominal input of 75,000 BTU/h or less was able to have an energy factor as low as 53%, while under the 2015 standard, the minimum energy factor for a 75-US-gallon gas storage tank water heater is now 74%, which can only be achieved by using condensing technology. Storage water heaters with a nominal input of 75,000 BTU/h or greater are not currently affected by these requirements, since energy factor is not defined for such units. An 80 USgal electric storage tank water heater was able to have a minimum energy factor of 86% under the pre-2015 standard, while under the 2015 standard, the minimum energy factor for an 80-gallon electric storage tank water heater is now 197%, which is only possible with heat pump technology. This rating measures efficiency at the point of use.

Depending on how electricity is generated, overall efficiency may be much lower. For example, in a traditional coal plant, only about 30–35% of the energy in the coal ends up as electricity on the other end of the generator. Losses on the electrical grid (including line losses and voltage transformation losses) reduce electrical efficiency further. According to data from the Energy Information Administration, transmission and distribution losses in 2005 consumed 6.1% of net generation. In contrast, 90% of natural gas's energy value is delivered to the consumer. (In neither case is the energy expended exploring, developing and extracting coal or natural gas resources included in the quoted efficiency numbers.) Gas tankless water heaters shall have an energy factor of 82% or greater under the 2015 standards, which corresponds to the pre-2015 Energy Star standard.

In 2022 the Department of Energy proposed rules that would take effect in 2026 and would effectively eliminate inefficient non-condensing gas water heaters in commercial buildings. Non-condensing models waste heat, while condensing models capture and used otherwise lost energy. The change will reduce emissions by 38 million tons of carbon dioxide over 30 years and reduce buildings' energy costs.

Explosion hazard

Water heaters potentially can explode and cause significant damage, injury, or death if certain safety devices are not installed. A safety device called a temperature and pressure relief (T&P or TPR) valve, is normally fitted on the top of the water heater to dump water if the temperature or pressure becomes too high. Most plumbing codes require that a discharge pipe be connected to the valve to direct the flow of discharged hot water to a drain, typically a nearby floor drain, or outside the living space. Some building codes allow the discharge pipe to terminate in the garage.

If a gas or propane fired water heater is installed in a garage or basement, many plumbing codes require that it be elevated at least 18 in above the floor to reduce the potential for fire or explosion due to spillage or leakage of combustible liquids in the garage. Furthermore, certain local codes mandate that tank-type heaters in new and retrofit installations must be secured to an adjacent wall by a strap or anchor to prevent tipping over and breaking the water and gas pipes in the event of an earthquake.

For older houses where the water heater is part of the space heating boiler, and plumbing codes allow, some plumbers install an automatic gas shutoff (such as the "Watts 210") in addition to a TPR valve. When the device senses that the temperature reaches 99 °C, it shuts off the gas supply and prevents further heating. In addition, an expansion tank or exterior pressure relief valve must be installed to prevent pressure buildup in the plumbing from rupturing pipes, valves, or the water heater.

Thermal burns (scalding)
Scalding is a serious concern with any water heater. Human skin burns quickly at high temperature, in less than 5 seconds at 60 °C, but much slower at 53 °C — it takes a full minute for a second degree burn. Older people and children often receive serious scalds due to disabilities or slow reaction times. In the United States and elsewhere it is common practice to put a tempering valve or thermostatic mixing valve on the outlet of the water heater. The result of automatically mixing hot and cold water via a tempering valve is referred to as "tempered water".

A tempering valve mixes enough cold water with the hot water from the heater to keep the outgoing water temperature fixed at a more moderate temperature, often set to 50 °C. Without a tempering valve, reduction of the water heater's setpoint temperature is the most direct way to reduce scalding. However, for sanitation, hot water is needed at a temperature that can cause scalding. This may be accomplished by using a supplemental heater in an appliance that requires hotter water. Most residential dishwashing machines, for example, include an internal electric heating element for increasing the water temperature above that provided by a domestic water heater.

Bacterial contamination
Two conflicting safety issues affect water heater temperature—the risk of scalding from excessively hot water greater than 55 °C, and the risk of incubating bacteria colonies, particularly Legionella, in water that is not hot enough to kill them. Both risks are potentially life-threatening and are balanced by setting the water heater's thermostat to 55 °C. The European Guidelines for Control and Prevention of Travel Associated Legionnaires' Disease recommend that hot water should be stored at 60 °C and distributed so that a temperature of at least 50 °C and preferably 55 °C is achieved within one minute at points of use.

If there is a dishwasher without a booster heater, it may require a water temperature within a range of 57 - 60 °C for optimum cleaning, but tempering valves set to no more than 55 °C can be applied to faucets to avoid scalding. Tank temperatures above 60 °C may produce limescale deposits, which could later harbor bacteria, in the water tank. Higher temperatures may also increase etching of glassware in the dishwasher.

Tank thermostats are not a reliable guide to the internal temperature of the tank. Gas-fired water tanks may have no temperature calibration shown. An electric thermostat shows the temperature at the elevation of the thermostat, but water lower in the tank can be considerably cooler. An outlet thermometer is a better indication of water temperature.

In the renewable energy industry (solar and heat pumps, in particular) the conflict between daily thermal Legionella control and high temperatures, which may drop system performance, is subject to heated debate. In a paper seeking a green exemption from normal Legionellosis safety standards, Europe's top CEN solar thermal technical committee TC 312 asserts that a 50% fall in performance would occur if solar water heating systems were heated to the base daily. However some solar simulator analysis work using Polysun 5 suggests that an 11% energy penalty is a more likely figure. Whatever the context, both energy efficiency and scalding safety requirements push in the direction of considerably lower water temperatures than the legionella pasteurization temperature of around 60 °C.

Legionella pneumophila has been detected at the point of use downstream from horizontally-mounted electric water heaters with volumes of 150 Liters.

However, legionella can be safely and easily controlled with good design and engineering protocols. For instance raising the temperature of water heaters once a day or even once every few days to 55 °C at the coldest part of the water heater for 30 minutes effectively controls legionella. In all cases and in particular energy efficient applications, Legionnaires' disease is more often than not the result of engineering design issues that do not take into consideration the impact of stratification or low flow.

It is also possible to control Legionella risks by chemical treatment of the water. This technique allows lower water temperatures to be maintained in the pipework without the associated Legionella risk. The benefit of lower pipe temperatures is that the heat loss rate is reduced and thus the energy consumption is reduced.

title: Water heating


text:
Talk:Blue Devils

This seems to be straight out of the student handbook, verbatim. Copyright infringement?

Drunkasian 15:12, 12 Mar 2004 (UTC)

Removals and reasons
Please add these back when articles are present or anticipated:

Red-links

 * The Blue Devils, the mascot for Elite Cheer & Dance (An all-star cheerleading team in Davie, Florida).

No-links

 * Blue Devils is also the mascot of numerous secondary schools.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Talk:Blue Devils


text:
Genome (book)

Genome: The Autobiography of a Species in 23 Chapters is a 1999 popular science book by the science writer Matt Ridley, published by Fourth Estate. The chapters are numbered for the pairs of human chromosomes, one pair being the X and Y sex chromosomes, so the numbering goes up to 22 with Chapter X and Y couched between Chapters 7 and 8.

The book was welcomed by critics in journals such as Nature and newspapers including The New York Times. The London Review of Books however found the book "at once instructive and infuriating", as "his right-wing politics lead him to slant the implications of the research".

Context
The book's author, Matt Ridley, is a British journalist and businessman, known for writing on science, the environment, and economics. He studied zoology, gaining his DPhil in 1983.

Structure
The book devotes one chapter to each pair of human chromosomes. Since one (unnumbered) chapter is required to discuss the sex chromosomes, the final chapter is number 22. Ridley was inspired to adopt this model by Primo Levi's book The Periodic Table.

 * Chapter 1, Life

The first chapter begins with a quote from Alexander Pope on the cycle of life. The very broad topic "Life" is also the topic of the chapter. Ridley discusses the history of the gene briefly, including our "last universal common ancestor".

 * Chapter 2, Species

Ridley discusses the history of human kind as a genetically distinct species. He compares the human genome to chimpanzees, and ancestral primates. He also points out that until the 19th century, most scholars believed that there were 24 sets of genes, not 23 as known today.

 * Chapter 3, History

This chapter discusses the interplay between early geneticists, including Gregor Mendel, Charles Darwin, Hermann Joseph Muller and Francis Crick.

 * Chapter 4, Fate

Huntington's chorea is used to discuss the use of a particular sequence on Chromosome Four to cause traumatic health consequences. The search for the chromosomal source of this and other related diseases is discussed through the work of Nancy Wexler, someone who may have inherited the gene but who turns to scientific work to study it in others.

 * Chapter 5, Environment

The concepts of pleiotropy and genetic pluralism are introduced. A brief history of the study of asthma is used as the case study. Asthma is related to as many as fifteen different genes, many on chromosome five. Specifically, this includes a change from adenosine (A) to guanine (G) at position 46 on the ADRB2 gene. The ADRB2 gene is related to the control of bronchodilation and bronchoconstriction.

 * Chapter 6, Intelligence

Robert Plomin's announcement in 1997 of the discovery of "a gene for intelligence" on chromosome 6 is the foundation for this chapter's lengthier discussion of the genetic basis for intelligence. This included gene IGF2R on the long arm of chromosome 6, which may also be related to liver cancer. Ridley continues his premise in this chapter that the use of simple genetic markers is inadequate to describe the complete function of the genome, or the causation of disease.

 * Chapter 7, Instinct

This chapter discusses whether the form and existence of language has a genetic component. In particular, "specific language impairment" is possibly related to a gene on chromosome 7. Ridley discusses the scientific disagreement between Canadian linguist Myrna Gopnik and others on whether this disorder relates to difficulties with grammar formulation, or is a broader intellectual disorder.

 * Chapter X and Y, Conflict

Ridley contemplates evolutionary psychology using the genes SRY on the Y chromosome, and DAX1 and Xq28 on the X chromosome. The theory of genetic conflict and evolution is debated using the rhetorical question, are we bodies containing genes, or genes in bodies?

 * Chapter 8, Self-Interest

Richard Dawkins's concept of the "selfish gene" is described by Ridley through a discussion of retrotransposons. This includes the behavior of the LINE-1 and Alu transposons. Further, Ridley discusses the possible purposes of cytosine methylation in development. The chapter also discusses how, through reverse transcriptase, retroviruses like HIV copy themselves to the human genome.

 * Chapter 9, Disease

For chromosome 9, the book examines the discussion of the blood-typing genetic sequences. Namely, the ABO blood groups and their impact on evolution are discussed. Other genes mentioned include CFTR for cystic fibrosis. Ridley concludes that the Human Genome Project is largely based on the inaccurate belief that there is one single human genome. Proof that this is wrong comes from answering the question, which of the several choices of blood typing genetic sequence is selected, since each one has different disease-resistant and evolutionary consequences?

 * Chapter 10, Stress

The impact of stress on the human body is described starting with the creation of hormones by the CYP17 gene on chromosome 10. Ridley points out the relationship between cholesterol, steroidal hormones such as progesterone, cortisol, aldosterone, testosterone and oestradiol.

 * Chapter 11, Personality

Ridley chooses the gene D4DR which codes for the manufacture of dopamine and is located on the short arm of chromosome 11. Interactions between dopamine, serotonin and other serotonin neurochemistry are lightly covered.

 * Chapter 12, Self-Assembly

This chapter relates to how understanding the genetic code matches models for embryonic development among vertebrates. Ridley discusses 'gap' genes, 'pair-rule' genes, and 'segment-polarity' genes. Homeotic genes and Hox genes are described briefly. Walter Gehring's discovery of the homeobox set of codes in 1983 is related to an on and off switch metaphorically.

 * Chapter 13, Pre-History

Ridley describes the relationship between the development of Indo-European and other ancient root languages and the classical polymorphisms which map genetic frequencies in Eurasia. The interplay between the breast cancer genes BRCA2 on chromosome 13 and BRCA1 on chromosome 17 help to illustrate these larger concepts. Ridley also describes genetic studies of different types of peoples to isolate why people developed a mutation allowing adults to digest lactase in adulthood. He concludes that since the herding tribes of the world all evolved this mutation earliest, these people's genes adapted to their environment. This may sound like Lamarck's tale of the blacksmith's strong arms 'handed down' to his sons, but it is not. The controversial conclusion is that willed action can alter our evolutionary history and genetic composition, by changing the environment to which we have to adapt.

 * Chapter 14, Immortality

This chapter examines the so-called "immortality" of the genetic code - i.e. how is it that genetic code can remain as precise as it has been for 50 billion copyings since the dawn of life? Part of the answer is in the protein enzyme telomerase, lying on chromosome 14 and coded by the gene TEP1.

 * Chapter 15, Sex

Ridley discusses two chromosome 15 genetic diseases, Prader-Willi syndrome and Angelman's syndrome: Prader-Willi inherited from the father, Angelman's from the mother, through sexual antagonism and the placenta's control by paternal genes.

 * Chapter 16, Memory

Ridley debates the old knowledge versus instinct problem, claiming that natural selection will be the explanation of the instinct for grammar, and noting that many animals including invertebrates can learn. All the same, he argues that the brain is controlled by genes and gene products.

 * Chapter 17, Death

The TP53 gene on chromosome 17 suppresses cancer cells, while oncogenes stimulate cell growth and can cause cancer if kept switched on, while TP53 can cause cancer when kept switched off. Other mutator genes like BRCA1 and BRCA2 contribute to breast cancer.
 * Chapter 18, Cures

Recombinant DNA enabled genetic manipulation with restriction enzymes and a ligase. Genetic engineering has been highly controversial, especially in food production; it might, writes Ridley, one day be used in humans.

 * Chapter 19, Prevention

It might be possible to prevent or cure Alzheimer's disease and coronary heart disease. APO genes like APOE influence fat and cholesterol metabolism. The E4 allele of EPOE contributes to the plaque buildup of Alzheimer's. Genetic testing may help patients take early preventative action.

 * Chapter 20, Politics

The sheep brain disease scrapie appeared to be infectious but did not involve a microorganism. The disaster of Creutzfeldt–Jakob disease in humans was found to be caused by the PRP gene which produces a prion protein that aggregates into clumps, destroying brain cells. Ridley attacks the panicky handling of prion disease outbreaks by governments.
 * Chapter 21, Eugenics

Eugenics a century ago, based on faulty knowledge of genetics, led to immoral actions by governments and the US Supreme Court, pushing through compulsory sterilization of people such as those with trisomy 21 which causes Down syndrome. Ridley discusses the conflict between society, in the form of the state, and the individual.

 * Chapter 22, Free Will

Ridley addresses the heated debate between genetic determinism and freedom. Children are moulded both by their peers (other children) and by their genes. He argues that behaviour is in the short term unpredictable, but "broadly" predictable in the long term.

Reception
Genome has been reviewed in scientific journals including Nature and in medical journals such as the New England Journal of Medicine, where Robert Schwartz notes that Ridley speculates, "sometimes wildly". The book is a "gambol" through the human chromosomes. All the same, Schwartz writes, the book is "instructive, challenging, and fun to read. I envy Ridley's talent for presenting, without condescension, complex sets of facts and ideas in terms comprehensible to outsiders."

Lee M. Silver, reviewing Genome in The New York Times, argues that the book's theme is that each individual's genome contains "echoes" (Ridley's word) of their ancestors' lives. Silver calls Ridley "adamant" in believing that the use of "personal genetics" must not be left for doctors or governments to control, following on from the mistakes of eugenics a century ago, but that it's a fundamental human right to "see and use the messages in their own DNA as they see fit." Silver describes the book as remarkable for focusing on "pure intellectual discovery", providing "delightful stories". He suggests that even practising geneticists will gain a sense of wonder from the "hidden secrets" in the book.

The biologist Jerry Coyne, writing in the London Review of Books, criticises Genome as "at once instructive and infuriating. For each nugget of science, Ridley also includes an error or misrepresentation. Some of these derive from poor scholarship: others from his political agenda." For example, Coyne mentions Ridley's incorrect claim that "half of your IQ is inherited"; that Ridley assumes that the marker used by Robert Plomin, IGF2R, is the purported "intelligence gene" that it marks; and that social influences on behaviour [always] work by switching genes on and off, something that Coyne states is "occasionally true". Coyne argues that Ridley is an "implacable" genetic determinist, denying the influence of the environment, and calling his politics "right-wing". He calls the book's structure "eccentric" and "bizarre", the chapters matching the 23 pairs of human chromosomes, and notes that Genome is the third of Ridley's books that "tries to popularise" evolutionary psychology.

The science writer Michael Shermer finds Ridley's technique "at once clever and delimiting: Each chapter represents a chromosome, for which he has chosen a single entity supposedly determined or influenced by that chromosome." In Shermer's view, "It is a facile literary device to help readers get their minds around this illimitable subject, but I fear that it gives the wrong impression, disclaimers notwithstanding, that such things as intelligence, instinct, or self-interest are wholly located on that chromosome (and, therefore, genetically programmed and biologically determined)."

Awards and distinctions
Genome was shortlisted for the Samuel Johnson Prize in 2000.

title: Genome (book)


text:
Iwahori–Hecke algebra

In mathematics, the Iwahori–Hecke algebra, or Hecke algebra, named for Erich Hecke and Nagayoshi Iwahori, is a deformation of the group algebra of a Coxeter group.

Hecke algebras are quotients of the group rings of Artin braid groups. This connection found a spectacular application in Vaughan Jones' construction of new invariants of knots. Representations of Hecke algebras led to discovery of quantum groups by Michio Jimbo. Michael Freedman proposed Hecke algebras as a foundation for topological quantum computation.

Hecke algebras of Coxeter groups
Start with the following data:

 * (W, S) is a Coxeter system with the Coxeter matrix M = (mst),
 * R is a commutative ring with identity.
 * {qs | s ∈ S} is a family of units of R such that qs = qt whenever s and t are conjugate in W
 * A is the ring of Laurent polynomials over Z with indeterminates qs (and the above restriction that qs = qt whenever s and t are conjugated), that is A = Z [q$±1 s$]

Multiparameter Hecke Algebras
The multiparameter Hecke algebra HR(W,S,q) is a unital, associative R-algebra with generators Ts for all s ∈ S and relations:
 * Braid Relations: Ts Tt Ts ... = Tt Ts Tt ..., where each side has mst < ∞ factors and s,t belong to S.
 * Quadratic Relation: For all s in S we have: (Ts - qs)(Ts + 1) = 0.

Warning: in later books and papers, Lusztig used a modified form of the quadratic relation that reads $$(T_s-q_s^{1/2})(T_s+q_s^{-1/2})=0.$$ After extending the scalars to include the half integer powers q$±1/2 s$ the resulting Hecke algebra is isomorphic to the previously defined one (but the Ts here corresponds to q$-1/2 s$ Ts in our notation). While this does not change the general theory, many formulae look different.

Generic Multiparameter Hecke Algebras
HA(W,S,q) is the generic multiparameter Hecke algebra. This algebra is universal in the sense that every other multiparameter Hecke algebra can be obtained from it via the (unique) ring homomorphism A → R which maps the indeterminate qs ∈ A to the unit qs ∈ R. This homomorphism turns R into a A-algebra and the scalar extension HA(W,S) ⊗A R is canonically isomorphic to the Hecke algebra HR(W,S,q) as constructed above. One calls this process specialization of the generic algebra.

One-parameter Hecke Algebras
If one specializes every indeterminate qs to a single indeterminate q over the integers (or q$1/2 s$ to q1/2 respectively), then one obtains the so-called generic one-parameter Hecke algebra of (W,S).

Since in Coxeter groups with single laced Dynkin diagrams (for example groups of type A and D) every pair of Coxeter generators is conjugated, the above-mentioned restriction of qs being equal qt whenever s and t are conjugated in W forces the multiparameter and the one-parameter Hecke algebras to be equal. Therefore, it is also very common to only look at one-parameter Hecke algebras.

Coxeter groups with weights
If an integral weight function is defined on W (i.e. a map L:W → Z with L(vw)=L(v)+L(w) for all v,w ∈ W with l(vw)=l(v)+l(w)), then a common specialization to look at is the one induced by the homomorphism qs ↦ qL(s), where q is a single indeterminate over Z.

If one uses the convention with half-integer powers, then weight function L:W → $1⁄2$Z may be permitted as well. For technical reasons it is also often convenient only to consider positive weight functions.

Properties
1. The Hecke algebra has a basis $$(T_w)_{w\in W}$$ over A indexed by the elements of the Coxeter group W. In particular, H is a free A-module. If $$w=s_1 s_2 \ldots s_n$$ is a reduced decomposition of w ∈ W, then $$T_w=T_{s_1}T_{s_2}\ldots T_{s_n}$$. This basis of Hecke algebra is sometimes called the natural basis. The neutral element of W corresponds to the identity of H: Te = 1.

2. The elements of the natural basis are multiplicative, namely, Tyw=Ty Tw whenever l(yw)=l(y)+l(w), where l denotes the length function on the Coxeter group W.

3. Elements of the natural basis are invertible. For example, from the quadratic relation we conclude that T$−1 s$ = q$−1 s$ Ts + (q$−1 s$-1).

4. Suppose that W is a finite group and the ground ring is the field C of complex numbers. Jacques Tits has proved that if the indeterminate q is specialized to any complex number outside of an explicitly given list (consisting of roots of unity), then the resulting one parameter Hecke algebra is semisimple and isomorphic to the complex group algebra C[W] (which also corresponds to the specialization q ↦ 1).

5. More generally, if W is a finite group and the ground ring R is a field of characteristic zero, then the one parameter Hecke algebra is a semisimple associative algebra over R[q±1]. Moreover, extending earlier results of Benson and Curtis, George Lusztig provided an explicit isomorphism between the Hecke algebra and the group algebra after the extension of scalars to the quotient field of R[q±1/2]

Canonical basis
A great discovery of Kazhdan and Lusztig was that a Hecke algebra admits a different basis, which in a way controls representation theory of a variety of related objects.

The generic multiparameter Hecke algebra, HA(W,S,q), has an involution bar that maps q1/2 to q−1/2 and acts as identity on Z. Then H admits a unique ring automorphism i that is semilinear with respect to the bar involution of A and maps Ts to T$−1 s$. It can further be proved that this automorphism is involutive (has order two) and takes any Tw to $$T^{-1}_{w^{-1}}.$$

Kazhdan - Lusztig Theorem: For each w ∈ W there exists a unique element $$C^{\prime}_w$$ which is invariant under the involution i and if one writes its expansion in terms of the natural basis:
 * $$ C'_w= \left (q^{-1/2} \right )^{l(w)}\sum_{y\leq w}P_{y,w}T_y, $$

one has the following:
 * Pw,w=1,
 * Py,w in Z[q] has degree less than or equal to $1⁄2$(l(w)-l(y)-1) if y<w in the Bruhat order,
 * Py,w=0 if $$y\nleq w.$$

The elements $$C^{\prime}_w$$ where w varies over W form a basis of the algebra H, which is called the dual canonical basis of the Hecke algebra H. The canonical basis {Cw | w ∈ W} is obtained in a similar way. The polynomials Py,w(q) making appearance in this theorem are the Kazhdan–Lusztig polynomials.

The Kazhdan–Lusztig notions of left, right and two-sided cells in Coxeter groups are defined through the behavior of the canonical basis under the action of H.

Hecke algebra of a locally compact group
Iwahori–Hecke algebras first appeared as an important special case of a very general construction in group theory. Let (G,K) be a pair consisting of a unimodular locally compact topological group G and a closed subgroup K of G. Then the space of K-biinvariant continuous functions of compact support, Cc(K\G/K), can be endowed with a structure of an associative algebra under the operation of convolution. This algebra is denoted by H(G//K) and called the Hecke ring of the pair (G,K).

Example: If G = SL(n,Qp) and K = SL(n,Zp) then the Hecke ring is commutative and its representations were studied by Ian G. Macdonald. More generally if (G,K) is a Gelfand pair then the resulting algebra turns out to be commutative.

Example: If G = SL(2,Q) and K = SL(2,Z) we get the abstract ring behind Hecke operators in the theory of modular forms, which gave the name to Hecke algebras in general.

The case leading to the Hecke algebra of a finite Weyl group is when G is the finite Chevalley group over a finite field with pk elements, and B is its Borel subgroup. Iwahori showed that the Hecke ring H(G//B) is obtained from the generic Hecke algebra Hq of the Weyl group W of G by specializing the indeterminate q of the latter algebra to pk, the cardinality of the finite field. George Lusztig remarked in 1984 (Characters of reductive groups over a finite field, xi, footnote):

 * I think it would be most appropriate to call it the Iwahori algebra, but the name Hecke ring (or algebra) given by Iwahori himself has been in use for almost 20 years and it is probably too late to change it now.

Iwahori and Matsumoto (1965) considered the case when G is a group of points of a reductive algebraic group over a non-archimedean local field K, such as Qp, and K is what is now called an Iwahori subgroup of G. The resulting Hecke ring is isomorphic to the Hecke algebra of the affine Weyl group of G, or the affine Hecke algebra, where the indeterminate q has been specialized to the cardinality of the residue field of K.

Work of Roger Howe in the 1970s and his papers with Allen Moy on representations of p-adic GL(n) opened a possibility of classifying irreducible admissible representations of reductive groups over local fields in terms of appropriately constructed Hecke algebras. (Important contributions were also made by Joseph Bernstein and Andrey Zelevinsky.) These ideas were taken much further in Colin Bushnell and Philip Kutzko's theory of types, allowing them to complete the classification in the general linear case. Many of the techniques can be extended to other reductive groups, which remains an area of active research. It has been conjectured that all Hecke algebras that are ever needed are mild generalizations of affine Hecke algebras.

Representations of Hecke algebras
It follows from Iwahori's work that complex representations of Hecke algebras of finite type are intimately related with the structure of the spherical principal series representations of finite Chevalley groups.

George Lusztig pushed this connection much further and was able to describe most of the characters of finite groups of Lie type in terms of representation theory of Hecke algebras. This work used a mixture of geometric techniques and various reductions, led to introduction of various objects generalizing Hecke algebras and detailed understanding of their representations (for q not a root of unity). Modular representations of Hecke algebras and representations at roots of unity turned out to be related with the theory of canonical bases in affine quantum groups and combinatorics.

Representation theory of affine Hecke algebras was developed by Lusztig with a view towards applying it to description of representations of p-adic groups. It is different in many ways from the finite case. A generalization of affine Hecke algebras, called double affine Hecke algebra, was used by Ivan Cherednik in his proof of the Macdonald's constant term conjecture.

title: Iwahori–Hecke algebra


text:
D channel

D channel (delta channel) is a telecommunications term which refers to the ISDN channel in which the control and signalling information is carried.

The bit rate of the D channel of a basic rate interface is 16 kbit/s, whereas it amounts to 64 kbit/s on a primary rate interface.

For DSS1 signalling, the D channel layer 2 protocol is Q.921 also called LAPD and it carries Layer 3 messages according to Q.931 protocol.

title: D channel


text:
Nidaros

Nidaros, Niðarós or Niðaróss was the medieval name of Trondheim when it was the capital of Norway's first Christian kings. It was named for its position at the mouth (Old Norse: óss) of the River Nid (the present-day Nidelva).

Although the capital was later moved to Oslo (around the year 1300), Nidaros remained the centre of Norway's spiritual life until the Protestant Reformation. The Archdiocese of Nidaros was separated from Lund (in Scania) by the papal legate Nicholas Breakspeare in 1152, and the shrine to Saint Olaf in Nidaros Cathedral was Northern Europe's most important pilgrimage site during the Middle Ages. Archbishop Olav Engelbrektsson led Norway in its attempted resistance against the Danish Reformation, and was forced into exile by King Christian III in 1537. The archdiocese was abolished and replaced with a Lutheran diocese.

Pre-Reformation
The Christianization of Norway was begun by Haakon the Good (d. 961) and was continued by Olaf Trygvesson (d. 1000) and Saint Olaf Haraldsson (d. 1030), two Vikings who had converted (and been baptized) at Andover in England and Rouen in Normandy, respectively. Olaf Trygvesson founded Nidaros in 997, and built a Kongsgård estate and church there. From this base, he worked to spread Christianity in Norway, Orkney, Shetland, the Faroes, Iceland, and Greenland.

Olaf Haraldsson established Nidaros as a see, and installed the monk Grimkill as its first bishop. Since Norway had no universities at the time, many English and German priests were brought in for its parishes and dioceses. The Norwegian bishops were at first dependent on Hamburg, and then (after 1103) on Lund in Denmark.

Pope Eugene III resolved to create a metropolitan see at Nidaros, and sent Nicholas Breakspeare as his legate in 1151. Nicholas installed Jon Birgerson, bishop of Stavanger, as the first archbishop of Nidaros. The bishops of Oslo (established 1073), Bergen (c. 1060), Stavanger (1130), Hamar (1151), Orkney (1070), Skálholt (1056) and Hólar (1105) in Iceland, and Garđar in Greenland were made its suffragans.

Jon Birgerson was succeeded as archbishop by Eystein (Beatus Augustinus, 1158–88), former royal secretary and treasurer and an intelligent, strong-willed, pious man. Those characteristics were needed to defend the Catholic Church against King Sverre, who wanted to make the church a tool of temporal power. The archbishop fled from him to England, returning after a lukewarm reconciliation with the king. Sverre renewed his attacks at Eystein's death, and Archbishop Eric took refuge with Archbishop Absalon of Lund. When Sverre attacked the papal legate, Pope Innocent III placed the king and his partisans under interdict.

King Håkon III Sverresson (1202), son and successor of Sverre, made peace with the church whose liberty was preserved by the support of the pope and his archbishops. Norwegian Protestant ecclesiastical historian Anton Christian Bang asked what would have happened "if the Church, deprived of all liberty, had become the submissive slave of absolute royalty? What influence would it have exercised at a time when its chief mission was to act as the educator of the people and as the necessary counterpoise to defend the liberty of the people against the brutal whims of the secular lords? And what would have happened when a century later royalty left the country? After that time the Church was, in reality, the sole centre of which was grouped the whole national life of our country".

To regulate ecclesiastical affairs (which had suffered during the struggles with Sverre), Innocent IV sent Cardinal William of Sabina as legate to Norway in 1247. He intervened against encroachments by bishops, reformed abuses, and abolished the ordeal by hot iron. Due to the papal legates, Norway became more closely linked with the pope. Secular priests and Benedictines, Cistercians, Augustinians, Dominicans, and Franciscans worked together for the prosperity of the church. Archbishops Eilif Kortin (d. 1332), Paul Baardson (d. 1346) and Arne Vade (d. 1349) were most notable. Provincial councils were held at which efforts were made to eliminate abuses and to encourage Christian education and morality.

St. Olaf, Norway's patron saint and Rex perpetuus Norvegiae (perpetual king of Norway), is entombed at Nidaros and the national and ecclesiastical life of the country was centred there. His tomb was a site of pilgrimage. The feast of St. Olaf on 29 July was a day of reunion for "all the nations of the Northern seas, Norwegians, Swedes, Goths, Cimbrians, Danes and Slavs" in the cathedral of Nidaros, where the saint's reliquary was near the altar. Built in Romanesque style by King Olaf Kyrre (d. 1093), the cathedral was enlarged by Archbishop Eystein in ogival style. It was finished in 1248 by Archbishop Sigurd Sim. Although the cathedral was damaged several times by fire, it was restored each time until the Reformation.

Archbishop Erik Valkendorf was exiled in 1521. His successor, Olaf Engelbrektsson (the instrument of the royal will in the introduction of Lutheranism and a partisan of King Christian II of Denmark and Norway), fled from the threat of Christian III (1537). The reliquaries of St. Olaf and St. Augustine (Eystein) were taken to Copenhagen and melted down. The bones of St. Olaf were buried, unmarked, in the cathedral.

Present day
When Norway regained self-rule as a separate kingdom in a union with Sweden in 1814, a period of national romanticism began in which attention was paid to the remnants of the independent medieval kingdom. It was resolved to restore the ancient cathedral of Nidaros.

Trondheim briefly changed its name back to Nidaros on January 1, 1930. After widespread opposition to the name, the Norwegian Parliament (led by Ivar Lykke) restored the city's name on March 6, 1931.

The pilgrimage route to Nidaros Cathedral has been revived. Using Norwegian spelling, the route is known as Saint Olav's Way. The main, 640 km route begins in the ruins of Oslo's Old City (Gamlebyen) and heads north along the lake Mjøsa, up Gudbrandsdalen, over Dovrefjell and down the Oppdal valley to the cathedral. Oslo has an office to advise pilgrims, and the Trondheim cathedral has a pilgrim centre which awards certificates to pilgrims who complete their journey.

The modern Lutheran diocese of Trondheim is known as Nidaros. The Roman Catholic archdiocese, suppressed in 1537, was restored as the Mission sui iuris of central Norway (on territory split off from the Apostolic Vicariate of Norway) on April 7, 1931. In 1935 it became the apostolic prefecture of central Norway, the apostolic vicariate of central Norway on February 4, 1953, and became the Roman Catholic Territorial Prelature of Trondheim on March 28, 1979.

title: Nidaros


text:
Cloris Leachman

Cloris Leachman (April 30, 1926 – January 27, 2021) was an American actress and comedienne whose career spanned nearly eight decades. She won many accolades, including eight Primetime Emmy Awards from 22 nominations, making her the most nominated and, along with Julia Louis-Dreyfus, most awarded performer in Emmy history. Leachman also won an Academy Award, a BAFTA Award, and a Golden Globe Award. In her early career, she was known for her versatility. Another unique trait of Leachman's acting style was her distinctive physicality, where she utilized props to accentuate and express her roles' characterizations.

Born and raised in Des Moines, Iowa, Leachman attended Northwestern University and began appearing in local plays as a teenager. After competing in the 1946 Miss America pageant, she secured a scholarship to study under Elia Kazan at the Actors Studio in New York City, making her professional debut in 1948. In film, she appeared in Peter Bogdanovich's The Last Picture Show (1971) as the neglected wife of a closeted schoolteacher in the 1950s; she won the Academy Award for Best Supporting Actress and the BAFTA Award for Best Actress in a Supporting Role. She was part of Mel Brooks's ensemble cast, playing Frau Blücher in Young Frankenstein (1974), Nurse Diesel in High Anxiety (1977) and Madame Defarge in History of the World, Part I (1981).

Leachman won additional Emmys for her role on The Mary Tyler Moore Show (1970-1975) and a Golden Globe for the spinoff Phyllis (1975-1977), in which she starred. She also appeared in television film A Brand New Life (1973); the variety sketch show Cher (1975); the ABC Afterschool Special production The Woman Who Willed a Miracle (1983); and the television shows Promised Land (1998) and Malcolm in the Middle (2000–06). Her other television credits include Gunsmoke (1961), Wagon Train (1962), The Twilight Zone (1961; 2003), and Raising Hope (2010–2014). She also acted in the films Butch Cassidy and the Sundance Kid (1969), WUSA (1970), Yesterday (1981), Castle in the Sky (1986), Spanglish (2004), and Mrs. Harris (2005). She wrote her memoir Cloris: My Autobiography (2009).

Early life and education
Leachman was born on April 30, 1926, in Des Moines, Iowa, the eldest of three daughters. Her parents were Cloris (née Wallace) and Berkeley Claiborne "Buck" Leachman. Her father worked at the family-owned Leachman Lumber Company. Her youngest sister, Claiborne Cary, was an actress and singer. Her other sister, Mary, was not in show business. Their maternal grandmother was of Bohemian (Czech) descent. Leachman attended Theodore Roosevelt High School.

As a teenager, Leachman appeared in plays by local youth on weekends at Drake University in Des Moines. After graduating from high school, she enrolled at Northwestern University in the School of Education. At Northwestern, she became a member of Gamma Phi Beta and was a classmate of future comic actors Paul Lynde and Charlotte Rae. She began appearing on television and in films shortly after competing in Miss America in 1946 as Miss Chicago.

1948–1967: Rise to prominence
After winning a scholarship in the Miss America pageant, placing in the top 16, Leachman studied acting under Elia Kazan at the Actors Studio in New York City. She had been cast as a replacement for the role of Nellie Forbush during the original run of Rodgers and Hammerstein's South Pacific. A few years later, she appeared in the Broadway-bound production of William Inge's Come Back, Little Sheba, but left the show before it reached Broadway when Katharine Hepburn asked her to co-star in a production of William Shakespeare's As You Like It. Leachman was slated to play the role of Abigail Williams in the original Broadway cast of Arthur Miller's seminal drama The Crucible. The production played four preview performances at the Playhouse Theatre in Wilmington, Delaware, from January 15–17, 1953, prior to opening on Broadway on January 22. However, Leachman left the production the day before opening night in Wilmington, with Madeleine Sherwood assuming the role. Leachman's name was heavily publicized prior to the production's opening, and her name still appeared in the printed program; a sign appeared at the box office in Wilmington noting the change.

Leachman appeared in many live television broadcasts in the 1950s, including such programs as Suspense and Studio One. She played opposite John Forsythe in Alfred Hitchcock Presents Season 1, Episode 2 "Premonition", which aired 10/8/1955. She also briefly held the role of the mother of "Lassie's" second master Timmy (Jon Provost) until she was replaced late in her only season with the cast by June Lockhart due to contract disputes. She made her feature-film debut as an extra in Carnegie Hall (1947), but her first real role was in Robert Aldrich's film noir Kiss Me Deadly, released in 1955. Leachman was several months pregnant during the filming, and appears in one scene running down a darkened highway wearing only a trench coat. A year later, she appeared opposite Paul Newman and Lee Marvin in The Rack (1956). She appeared with Newman again in a brief role in Butch Cassidy and the Sundance Kid (1969). She continued to work mainly in television, with appearances on Rawhide and in The Twilight Zone episode "It's a Good Life", as well as the sequel "It's Still a Good Life" in the 2002–2003 UPN series revival. During this period, Leachman appeared opposite John Forsythe on the anthology Alfred Hitchcock Presents in an episode titled "Premonition" (1955). In 1956 she guest starred as "Flory Tibbs", in a complex role as an abused captive on the TV Western Gunsmoke in S2E1's "Legal Revenge". She later appeared as Ruth Martin, Timmy Martin's adoptive mother, in the last half of season four (1957) of Lassie. Jon Provost, who played Timmy, said, "Cloris did not feel particularly challenged by the role. Basically, when she realized that all she'd be doing was baking cookies, she wanted out." She was replaced by June Lockhart in 1958.

That same year, she appeared in an episode of One Step Beyond titled "The Dark Room", with Marcel Dalio, in which she portrayed an American photographer living in Paris. In 1960, she played Marilyn Parker, the roommate of Janice Rule's character, Elena Nardos, in the Checkmate episode "The Mask of Vengeance". In 1961, she starred as Boni, a cold-hearted woman that would sell out her man for $500 in the TV Western Gunsmoke (S6E36 - "For The Love of Money). She appeared in The Twilight Zone S3 E8 "It's a Good Life" which aired 11/2/1961. Also in 1961, she appeared in The Donna Reed Show (S4E4 - Mouse at Play) as Donna Stone's friend Iris. In 1962, she appeared in "The Nancy Davis Story" as a forlorn bar maid desperate for love on Wagon Train (S5E33), plus she co-starred in "Trial by Fire", on an episode of Laramie that same year, as well as the "Where Beauty Lies" episode of Alfred Hitchcock Presents opposite George Nader. In 1966, she guest-starred on Perry Mason as Gloria Shine in "The Case of the Crafty Kidnapper". In late 1970, Leachman starred in one episode of That Girl as Don Hollinger's sister, Sandy.

1968–1989: Stardom and acclaim
In the drama film The Last Picture Show (1971), based on the bestselling book by Larry McMurtry, Leachman played Ruth Popper, the high-school gym teacher's neglected wife, with whom Timothy Bottoms' character has an affair. The part was originally offered to Ellen Burstyn, but Burstyn wanted another role in the film. Director Peter Bogdanovich correctly predicted during production that Leachman would win an Oscar for her performance; she won for Best Supporting Actress. Critic Roger Ebert of the Chicago Sun-Times wrote of her performance, "The only real warmth comes from the Leachman ...The film is above all an evocation of mood. It is about a town with no reason to exist, and people with no reason to live there. The only hope is in transgression, as Ruth knows when she seduces Sonny, the boy half her age."

Leachman won acclaim portraying Phyllis Lindstrom on the CBS sitcom The Mary Tyler Moore Show. She acted alongside Mary Tyler Moore, Valerie Harper, Ed Asner, Ted Knight, and Betty White. Leachman played the recurring role of Mary Richards' snobbish, self-absorbed and interfering downstairs neighbor on the program for five years. The role earned her two Primetime Emmy Award for Outstanding Supporting Actress in a Comedy Series. She was subsequently featured in a spinoff series, Phyllis (1975–1977), for which Leachman won a Golden Globe Award. The series ran for two seasons. Leachman won a record-setting eight Primetime and one Daytime Emmy Awards, in addition to having been nominated more than 20 times.

Leachman appeared in three Mel Brooks films including the comedic horror satire Young Frankenstein (1974), in which the mere mention of the name of her character, Frau Blücher, elicits the loud neighing of horses (an homage to a cinematic villain stereotype). Christopher Connor of The Film Magazine wrote of her role that it provides "fine contrasts and plenty of comedic moments". She also acted in his thriller spoof High Anxiety (1977) as the demented villainess and psychiatric nurse Charlotte Diesel. In the epic satire History of the World: Part I (1981) she portrayed Madame Defarge.

In 1977, she guest-starred on The Muppet Show, episode 2.24. In 1978, she won the Sarah Siddons Award for her work in Chicago theater. Leachman appeared in Disney's The North Avenue Irregulars in 1979, playing the role of Claire. In 1987, she hosted the VHS releases of Schoolhouse Rock! and portrayed the evil witch Griselda for Disney's Cannon Tales production of Hansel and Gretel. In 1986, she returned to television, replacing Charlotte Rae's character Edna Garrett as the den mother in The Facts of Life. Leachman's role as Edna's sister, Beverly Ann Stickle, continued until the end of the series two years later.

1989–2021: Final roles
In 1989, Leachman starred on Brooks' short-lived NBC sitcom The Nutt House in dual roles as head hotel housekeeper Mrs. Frick (a variation of the Frau Blücher character) and Mrs. Nutt, the senile owner of the hotel. During this time she worked as a voice actor in numerous animated films, including My Little Pony: The Movie (as the evil witch mother from the Volcano of Gloom), A Troll in Central Park (as Queen Gnorga), The Iron Giant, Gen13, and most notably as the voice of the cantankerous sky pirate Dola in Hayao Miyazaki's 1986 feature Castle in the Sky. She played a reclusive but eventually friendly neighbor who regains her Christmas spirit in Prancer. She played Ferris and Jeannie’s grandmother in the one season television series Ferris Bueller (TV series), episode 9, which aired in November of 1990. In 1993 she played a convincing Granny in the Penelope Spheeris film The Beverly Hillbillies. In 1999 Leachman starred in ‘Thanks’, a sitcom about a 17th century Puritan family that was cancelled after six episodes. Leachman played embittered, greedy, Slavic Canadian "Grandma Ida" on the Fox sitcom Malcolm in the Middle, for which she won an Emmy Award for Outstanding Guest Actress in a Comedy Series (2006). She was nominated for playing the character for six consecutive years.

Leachman's later television credits include the Lifetime Television miniseries Beach Girls with Rob Lowe and Julia Ormond. She took a comedic role as the wine-soaked former jazz singer and grandmother Evelyn in Spanglish (2004) opposite Adam Sandler for which she was nominated for a SAG Award. She had replaced an ailing Anne Bancroft in the role. The film reunited her with the Mary Tyler Moore Show writer, producer, and director James L. Brooks. That same year, she appeared with Sandler again in the remake of The Longest Yard. She also appeared in the Kurt Russell comedy Sky High as a school nurse with X-ray vision. In 2005, she guest-starred as Charlie Harper's neighbor Norma in an episode ("Madame and Her Special Friend") of Two and a Half Men. In 2006, Leachman's performance alongside Sir Ben Kingsley and Annette Bening in the HBO special Mrs. Harris earned her nominations for a Primetime Emmy Award, and a Screen Actors Guild Award. She auditioned to revive her role from Young Frankenstein in the 2007 Broadway production opposite Megan Mullally (who replaced Kristin Chenoweth) and Roger Bart. Andrea Martin was cast instead. Brooks was quoted as joking that Leachman, then 81, was too old for the role. "We don't want her to die on stage," Brooks (also 81, at the time) told columnist Army Archerd, a statement to which Leachman took umbrage. However, due to Leachman's success on Dancing with the Stars, Brooks then, doing a U-turn, reportedly asked her to reprise her role as Frau Blücher in the Broadway production of Young Frankenstein after the departure of Beth Leavel, who had succeeded Martin. The Broadway production closed before this could happen.

In 2008, Leachman was a contestant on the seventh season of Dancing with the Stars, paired with Corky Ballas, the oldest of the professionals and father of two-time champion Mark Ballas. Leachman is the oldest person to have competed on the show to date. She placed seventh in the competition. After Dancing with the Stars she guest starred on Disney Channel's Girl Meets World (2015), the Christian movie I Can Only Imagine (2018). Leachman made guest roles in the NBC sitcom The Office, the TV Land series Hot in Cleveland, the CBS drama Hawaii Five-0, and USA Network Royal Pains. During this time she portrayed a number of raunchy elderly women including Beerfest (2006), Scary Movie 4 (2006), and The Wedding Ringer (2015). From 2010 to 2014, She played another grandmother, Maw Maw, the matriarch of the family on the Fox sitcom Raising Hope, for which she was nominated for an Emmy Award for Outstanding Guest Actress in a Comedy Series.

One of Leachman's final roles was as Zorya Vechernyaya, one of the "old gods" who represented the evening star, in season one (2019) of the Showtime series American Gods. Leachman appears in the film Not To Forget (2021) in her final role. The movie, directed by Valerio Zanoli, stars Karen Grassle and 5 Academy Award winners: Cloris Leachman, Louis Gossett Jr, Tatum O'Neal, George Chakiris, and Olympia Dukakis.

On May 14, 2006, she was awarded an honorary doctorate in fine arts from Drake University.

Acting credits and awards

 * Leachman was inducted into the Television Academy Hall of Fame in 2011. That same year, she was ranked number 23 on the TV Guide Network special Funniest Women on TV.
 * On June 20, 2014, Leachman received an honorary degree from her alma mater, Northwestern University.
 * In 2017, she received PETA's Lifetime Achievement Award for her dedication to animal-rights issues.
 * She was awarded a Star on the Hollywood Walk of Fame in the Television Category on September 22, 1980, at 6435 Hollywood Boulevard.

Personal life
From 1953 to 1979, Leachman was married to Hollywood impresario George Englund. Her former mother-in-law was character actress Mabel Albertson. The marriage produced four sons and one daughter: Bryan (died 1986), Morgan, Adam, Dinah, and George. Some of them are in show business. Her son Morgan played Dylan on Guiding Light for several years. The Englunds were Bel Air neighbors of Judy Garland, Sid Luft, and their children, Lorna and Joey Luft, during the early 1960s. Lorna Luft stated in her memoir Me and My Shadows: A Family Memoir that Leachman was "the kind of mom I'd only seen on TV". Knowing of the turmoil at the Luft home, but never mentioning it, Leachman prepared meals for the children and made them feel welcome when they needed a place to stay.

Leachman was also a friend of Mort Sahl and Marlon Brando, whom she met while studying under Elia Kazan in the 1950s. She introduced him to her husband, who became close to Brando, as well, directing him in The Ugly American (1963) and writing a memoir about their friendship called Marlon Brando: The Way It's Never Been Done Before (2005).

Leachman was a vegetarian and an animal rights activist. In 1997, she appeared on the cover of Alternative Medicine Digest, posing nude while body-painted with images of fruit in a parody of Demi Moore's 1991 Vanity Fair cover photo. She also posed clad in a dress made of lettuce for a 2009 PETA advertisement. In 2013, she starred in a comedic PETA ad on spay and neuter in which she opened a condom wrapper with her teeth.

Leachman's granddaughter, Anabel Englund, is a singer. In addition to Anabel, Leachman had other grandchildren, and one great-grandson, Braden.

Leachman was an atheist.

Death
On January 27, 2021, Leachman died of natural causes in her sleep at her home in Encinitas, California, at the age of 94. Leachman's manager, Juliet Green, confirmed to People magazine that she had died on Wednesday, January 27, 2021. Leachman's son also confirmed this date to The New York Times. However, some sources cited a death date of January 26. Her body was cremated on February 7, 2021.

title: Cloris Leachman


text:
Quercus laevis

Quercus laevis, the turkey oak, is a member of the red oak group of oaks. It is native to the southeastern United States. The name turkey oak derives from the resemblance of the leaves to a turkey's foot. A Turkish and southern European species Quercus cerris is also commonly referred to as Turkey oak, so Quercus laevis is sometimes referred to as American turkey oak to distinguish it from the European species.

Description
Quercus laevis is a small tree, sometimes shrubby, typically only 8 - 10 m tall, though occasionally reaching 28 m. The leaves are variable in size, mostly 10 - 17 cm long but occasionally just 8 cm or as much as 30 cm long. They have 3–7 slender lobes, deeply incised between the lobes, each lobe with 1–3 bristle teeth at the tip. The leaves turn red in Autumn. The acorns are about 20 - 25 mm long, and, like other red oaks, take 18 months to mature.

Distribution and habitat
Turkey oak occurs on the coastal plain from Virginia south to southwestern Florida, and west to southeast Louisiana, where it mingles with many tropical trees such as mature coconut palms and large Cuban Laurel (Ficus) trees.

It typically grows on poor, thin, dry, rocky or sandy soils where few other oaks other than blackjack oak (Q. marilandica) can thrive. It does not have the beautiful crown form of many oaks, but is nonetheless a valuable tree for growing on infertile, dry, sandy sites. The deeply lobed leaves are also attractive. It associates as an understory tree with longleaf pine and other pine stands on sandy knolls in the southeastern United States.

title: Quercus laevis


text:
Deutsche Eishockey Liga

The Deutsche Eishockey Liga (for sponsorship reasons called PENNY Deutsche Eishockey Liga) (English: German Ice Hockey League) or DEL, is a German professional ice hockey league and the highest division in German ice hockey. Founded in 1994, it was formed as a replacement for the Eishockey-Bundesliga and became the new top-tier league in Germany as a result. Unlike the old Bundesliga, the DEL is not under the administration of the German Ice Hockey Federation.

Teams from the DEL participate in the IIHF's annual Champions Hockey League (CHL), competing for the European Trophy. Participation is based on the strength of the various leagues in Europe (excluding the European/Asian Kontinental Hockey League). Going into the 2022–23 CHL season, the DEL was ranked the No. 3 league in Europe, allowing them to send their top four teams to compete in the CHL.

In the 2016–17 season, the league was the second-best supported ice hockey league in Europe, behind the Swiss National League A, with an average attendance of 6,198 spectators per game. Fifteen different teams comprise the league, playing their home games in a diverse mix of venues, including a few large, modern arenas (e.g. in Berlin, Mannheim, Cologne, and Düsseldorf) and older, smaller venues (e.g. in Bietigheim, Schwenningen, and Straubing). Kölner Haie (English: Cologne Sharks), Düsseldorfer EG, and Eisbären Berlin (Berlin Polar Bears) all regularly attract over 15,000 fans for home games. Adler Mannheim (Mannheim Eagles) also regularly attract over 12,000 fans per home game with each of their home games in the 2019 DEL Playoffs, including all three games in the final series against EHC Red Bull München, selling out. Despite attracting some of the biggest crowds in the DEL, and hosting NHL teams in preseason games, Kölner Haie have not won a championship since 2002.

In the DEL Winter Game, similar to the NHL Winter Classic where matches are played in larger outdoor venues, Cologne and Düsseldorf have played in front of crowds in excess of 40,000, notably in 2019 as Düsseldorf won in overtime in rival Cologne's RheinEnergieStadion. The DEL Winter Game traditionally takes place every two years; four editions have been played since 2013, including games in Cologne and at the home of TSG Hoffenheim, with each attracting over 30,000 spectators. Following a 2021 postponement due to the ongoing COVID-19 pandemic, the DEL Winter Game is set to return in December 2022 with Cologne hosting Mannheim in the RheinEnergieStadion.

The DEL is known for its game-day atmosphere, as well as producing NHL talents including Dominik Kahun, Tim Stutzle and Lukas Reichel. Many of the German national team that took silver at the 2018 Winter Olympics in Pyeongchang played in the DEL, while EHC Red Bull München became the first German team to reach the Champions Hockey League final in 2019, losing to the Swedish team Frölunda HC. EHC Red Bull München followed this up by reaching the semi-finals in the 2021-22 Champions Hockey League. Ice hockey is growing as a sport in Germany and is seen as a popular alternative to football or handball, building upon the Olympic success in 2018.

A new system of promotion and relegation with the DEL2 began with the 2021–22 season, in which the last-placed DEL club will be replaced by the DEL2 champions. SC Bietigheim Steelers joined the DEL for the 2021-22 DEL season as DEL2 champions ahead of the first promotion/relegation to DEL2. Following the conclusion of the 2021–22 season, Bietigheim retained their place in the top flight while Krefeld Pinguine were relegated after finishing bottom of the table. Löwen Frankfurt (Frankfurt Lions) will be promoted as DEL2 champions for the 2022–23 season.

The DEL Playoffs determine the season champions in a similar format to the NHL. Each team plays 52 regular-season games to determine the regular-season champions before the top 10 teams are seeded and qualify for the playoffs. The top 6 teams receive a bye to the quarter-finals while the teams ranked 7–10 compete in the pre-playoff (wildcard) round. The seedings are re-calculated after each round in a straight knockout system. The DEL Finals, held in late April or early May, is a best-of-seven games format, similarly to the NHL where the top seed remaining holds home-field advantage in a Game 7 scenario.

For the 2021–22 season and 2020–21 season, a shortened version of the DEL playoffs was used in light of the COVID-19 pandemic. Eisbären Berlin won the 2022 Finals against EHC Red Bull München 3-1 in a best-of-5 format. Berlin also won the title in 2021, defeating Wolfsburg 2-1 in a best-of-3 series following a North/South regional league split during the 2020/21 season due to the pandemic.

The Eisbären Berlin and Adler Mannheim are the most successful DEL clubs and have won the last three editions between them (Mannheim 2019, Berlin 2021 & 2022). Mannheim have enjoyed a lot of success in recent years (2015 and 2019 Champions, 2021 Regular Season Champions) although EHC Red Bull München won three consecutive titles between 2016 and 2018 and also made the 2019 final, losing to Mannheim in five games. München were also top of the 2020 standings before the season was curtailed. ERC Ingolstadt (2014 Champions as the 9th seed) and Grizzlys Wolfsburg (2021 runners-up) have also enjoyed deep playoff runs in the last decade.

Some of the league's biggest rivalries include Kölner Haie and Düsseldorfer EG, Kölner Haie and Adler Mannheim, and Eisbären Berlin and EHC Red Bull München. The Bavarian Derbies between München, ERC Ingolstadt, Augsburger Panther, Straubing Tigers, and Nürnberg Ice Tigers are also fiercely contested. Due to geography, Nürnberg/Straubing and Augsburg/Ingolstadt are notable rivalries although Munich/Augsburg has become a stronger rivalry following their epic 2019 semi-final series. München won that series in the deciding game 7 which also included the longest match in DEL history, won by Augsburger Panther after 104 minutes of action in game 3, as two matches required three overtimes to determine a winner.

History
The Eishockey-Bundesliga was formed in 1957 as the elite hockey competition in the Federal Republic of Germany, replacing the Oberliga in this position. It was in turn replaced by the Deutsche Eishockey Liga, which now also carries the name 1st Bundesliga in its logo.

The DEL was founded in the 1994–95 season, consisting of teams from the Eishockey-Bundesliga's 1st and 2nd divisions. The condition of these earlier leagues had become intolerable. Many 1st and 2nd division teams were heavily in debt. The 2nd division attracted few sponsors and spectators. As a result, many clubs were forced to fold or withdraw to the lower leagues. Fans and corporate sponsors focused on the 1st Bundesliga teams, forcing the elite teams to invest heavily in players to avoid relegation. This increased budgets 25 percent over the previous two years.

In the final Bundesliga season, 1993–94, only 11 teams wanted to play in the 2nd Bundesliga. Furthermore, two teams folded during and after the season. Ice hockey's reputation in Germany was heavily tarnished. This made it difficult to attract serious sponsorship. In January 1994, 20 out of the remaining 21 1st and 2nd Bundesliga teams voted for creating a new entity, the DEL.

Upon founding, the "DEL Betriebsgesellschaft mbH" was the first German professional sports league managed by an organization whose members were incorporated as well. The goal behind the DEL was to create a league, based on the model of the North American NHL, in which teams could play consistently without relegation concerns and create a stable league. Clubs in the DEL were required to conform to rules, which were designed to ensure long-term viability. Twelve clubs from the old 1st Bundesliga, and six from the 2nd Bundesliga came together as founding members. The new league immediately attracted corporate sponsorship with the Krombacher Brewery, which was prominently featured on the new league logo.

The hope of avoiding the troubles of the old Bundesliga by stricter financial controls did not materialize. During DEL's initial season, on 18 December 1994, the Bundesliga's final champion, the renamed EC Hedos München, folded. This was controversial, as DEL's president Franz Hofherr had approved their license and certified their finances. Hofherr was Mad Dogs former president and it was alleged that he must have known about their desperate financial situation.

The Bosman ruling, a 1995 decision of the European Court of Justice regarding the movement of labor in soccer, had profound influence on the league. The old Bundesliga had national character with German clubs competing for the German title using mostly German players. After the ruling European Union players were excluded from the "foreign" player quota. In the 1995–96 season following the decision, the DEL teams employed 97 EU players. This lowered costs significantly, enabling smaller teams to compete more effectively. However, frequent player moves were not viewed positively by the fans, resulting in smaller attendance numbers.

Following an agreement with the DEB the league renamed itself as "DEL – Die 1. Bundesliga" in the 1999–2000 season, while reintroducing relegation and promotion to/from the 2nd Ice Hockey Bundesliga.

The 2004–05 season was significant due to the NHL lockout. 26 NHL players came to play the season in the DEL, including Jamie Langenbrunner, Erik Cole, Stéphane Robidas, Doug Weight, Mike York and several German national team players – Jochen Hecht, Olaf Kölzig, and Marco Sturm.

League regulations
The DEL is an independently run league, fully owned and operated by its 14 member teams. Each team must fulfill the DEL's basic requirements to remain in the league:
 * A written application for membership;
 * "On ice qualification" for new teams (championship in the 2nd Bundesliga);
 * A stadium that meets DEL standards;
 * Financial qualification;
 * Formation of an ordinary company (the DEL consists of franchises);
 * Development program for young players; and
 * Purchase of a license (currently, the licensing fee is set at €800,000.00)

The DEL can only admit one 2nd Bundesliga team per season to the league, unless the league strength falls below fourteen, in which case two clubs can be admitted. Since the 2006–07 season, no DEL team can be automatically relegated, a team can only lose its league status through non-compliance with the leagues regulations (see above).

The ESBG guarantees to admit any DEL team wishing to step down to the lower 2nd Bundesliga or Oberliga. The team, however, has to purchase a license (licensing fees for the 2nd Bundesliga are currently set at €100,000.00).

To regulate the relationship between the DEL, the DEB and the ESBG (2nd Bundesliga), a so-called Kooperationsvertrag exists. This cooperation contract was signed in December 2005, and was valid until 2011. This contract ended years of dispute between the three organizations over competencies and financial issues.

In November 2007, the DEL announced another change in policy. The league expanded to allow 16 teams beginning in the 2008–09 season, resulting in direct promotion for the 2nd Bundesliga league champions, should they fulfill all requirements and be interested in joining the DEL. Should this not be the case, or a current DEL team resigns from the league, a selection process would determine the club, or clubs, who would be eligible to join in order required to achieve 16 teams. (Note: Füchse Duisburg resigned before the 2009–10 season and was not replaced until the following season.)

For that season, it was also mandated that each DEL club would be allowed to have no more than ten non-EC players under contract.

Additionally, a new format for the game schedule will limit the number of regular-season games to 52 for each team. This is achieved by each team playing four games against eleven others and two games against the remaining four. To determine which teams play, the final standings of the previous season are used.

The DEL would also reintroduce promotion once more. The first- and second-lowest ranked teams will play a best-of-seven series to determine which team faces the 2nd Bundesliga champion for a place in the league. There is, however, an ongoing dispute about those games as second division teams may only have five foreign players on contract and therefore face a handicap in comparison to the DEL teams with twelve import players each. For now, the ESBG has declared that no team from the 2nd Bundesliga would take part in these matches and therefore no promotion/relegation with the DEL will take place.

Teams
Members of the 2023–24 DEL season.

Former teams

 * BSC Preussen Berlin later BSchC Preussen/Berlin Capitals, dissolved 2005 refounded as Eissport & Schlittschuh Club 2007 Berlin
 * Frankfurt Lions dissolved 5 July 2010 due to bankruptcy
 * Füchse Duisburg
 * ESG Füchse Sachsen Weißwasser/Chemnitz now Lausitzer Füchse
 * Hamburg Freezers ceased operations 24 May 2016
 * EC Hannover now Hannover Indians
 * Hannover Scorpions
 * Kassel Huskies dissolved 27 August 2010 due to bankruptcy
 * Kaufbeurer Adler
 * EV Landshut
 * Maddogs München dissolved 1994 due to bankruptcy
 * Moskitos Essen
 * Munich Barons relocated in 2002 to become Hamburg Freezers
 * EC Ratingen "Die Löwen" relocated in 1997 to become Revierlöwen Oberhausen
 * Revierlöwen Oberhausen
 * Starbulls Rosenheim
 * SC Riessersee
 * Wölfe Freiburg
 * Bietigheim Steelers
 * Krefeld Pinguine

Past champions

 * 1994–95 Kölner Haie
 * 1995–96 Düsseldorfer EG
 * 1996–97 Adler Mannheim
 * 1997–98 Adler Mannheim
 * 1998–99 Adler Mannheim
 * 1999–00 Munich Barons
 * 2000–01 Adler Mannheim
 * 2001–02 Kölner Haie
 * 2002–03 Krefeld Pinguine
 * 2003–04 Frankfurt Lions
 * 2004–05 Eisbären Berlin
 * 2005–06 Eisbären Berlin
 * 2006–07 Adler Mannheim
 * 2007–08 Eisbären Berlin
 * 2008–09 Eisbären Berlin
 * 2009–10 Hannover Scorpions
 * 2010–11 Eisbären Berlin
 * 2011–12 Eisbären Berlin
 * 2012–13 Eisbären Berlin
 * 2013–14 ERC Ingolstadt
 * 2014–15 Adler Mannheim
 * 2015–16 EHC München
 * 2016–17 EHC München
 * 2017–18 EHC München
 * 2018–19 Adler Mannheim
 * 2019–20 EHC München (RS) 7
 * 2020–21 Eisbären Berlin
 * 2021–22 Eisbären Berlin
 * 2022–23 EHC München
 * 2023–24 Eisbären Berlin

All-time standings
33 clubs have played in the DEL since founding, with 15 currently playing. The 1994 standing represents the Bundesliga and 2. Bundesliga.

title: Deutsche Eishockey Liga


text:
Talk:Poland's wedding to the sea

How about "Poland's Betrothal with the Sea"? Space Cadet 15:29, 12 Mar 2004 (UTC)

The proper title is "Poland's wedding to the sea." "Engagement"="betrothal" is only a preliminary to the "wedding" (zaslubiny).

Also, why did General Haller appear as "Haller de Hallenburg," when he is simply called "Haller" in histories? On that basis, why not list all of Charles de Gaulle's half-dozen given names each time? Putting in "de Hallenburg" tends to make Haller look pompous. (Which he may have been, but why perpetuate it?) I suggest dropping "de Hallenburg" from the title of the entry, "Jozef Haller de Hallenburg." It can be mentioned in the opening paragraph instead. Logologist 23:36, 12 Nov 2004 (UTC)

 * I replied in Talk:Józef Haller de Hallenburg. Halibutt 07:35, July 19, 2005 (UTC)

title: Talk:Poland's wedding to the sea