Editing Pipeline (section)

===District heating===
[[File:Fernwärmeleitung Dü StPö mit Kraftwerk Dürnrohr.jpg|thumb|200px|District heating pipeline in Austria with a length of 31&nbsp;km<ref name="Wärmetransportleitung">[http://www.gaswaerme.at/de/pdf/10-1/oberhammer.pdf Andreas Oberhammer; The longest heat transfer pipeline in Austria] {{webarchive|url=https://web.archive.org/web/20110706092155/http://www.gaswaerme.at/de/pdf/10-1/oberhammer.pdf |date=2011-07-06}} Paper in German. Retrieved 2010-09-20</ref>]]
{{Main|District heating}}

District heating or ''teleheating'' systems consist of a network of [[insulated pipe|insulated]] feed and return pipes which transport heated water, [[pressurized hot water]], or sometimes [[steam]] to the customer. While steam is hottest and may be used in [[industrial process]]es due to its higher temperature, it is less [[thermal efficiency|efficient]] to produce and transport due to greater heat losses. Heat transfer oils are generally not used for economic and ecological reasons. The typical annual loss of thermal energy through distribution is around 10%, as seen in Norway's district heating network.<ref>{{cite web |url=http://www.nve.no/global/energi/analyser/energi%20i%20norge%20folder/energy%20in%20norway%202009%20edition.pdf |title=Norwegian Water Resources and Energy Directorate |access-date=2011-09-25 |url-status=dead |archive-url=https://web.archive.org/web/20110928144652/http://www.nve.no/global/energi/analyser/energi%20i%20norge%20folder/energy%20in%20norway%202009%20edition.pdf |archive-date=2011-09-28}}
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District heating pipelines are normally installed underground, with some exceptions. Within the system, [[thermal energy storage|heat storage]] may be installed to even out peak load demands. Heat is transferred into the [[central heating]] of the dwellings through [[heat exchanger]]s at [[district heating substation|heat substations]], without mixing of the fluids in either system.