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class="vector-toc-list"> <li id="toc-Galvanized_steel" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Galvanized_steel"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1</span> <span>Galvanized steel</span> </div> </a> <ul id="toc-Galvanized_steel-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Aluminium" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Aluminium"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.2</span> <span>Aluminium</span> </div> </a> <ul id="toc-Aluminium-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Polyurethane_and_phenolic_insulation_panels_(pre-insulated_air_ducts)" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Polyurethane_and_phenolic_insulation_panels_(pre-insulated_air_ducts)"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.3</span> <span>Polyurethane and phenolic insulation panels (pre-insulated air ducts)</span> </div> </a> <ul id="toc-Polyurethane_and_phenolic_insulation_panels_(pre-insulated_air_ducts)-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Fiberglass_duct_board_(preinsulated_non-metallic_ductwork)" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Fiberglass_duct_board_(preinsulated_non-metallic_ductwork)"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.4</span> <span>Fiberglass duct board (preinsulated non-metallic ductwork)</span> </div> </a> <ul id="toc-Fiberglass_duct_board_(preinsulated_non-metallic_ductwork)-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Flexible_ducting" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Flexible_ducting"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.5</span> <span>Flexible ducting</span> </div> </a> <ul id="toc-Flexible_ducting-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Fabric_ducting" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Fabric_ducting"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.6</span> <span>Fabric ducting</span> </div> </a> <ul id="toc-Fabric_ducting-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-PVC_low-profile_ducting" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#PVC_low-profile_ducting"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.7</span> <span>PVC low-profile ducting</span> </div> </a> <ul id="toc-PVC_low-profile_ducting-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Waterproofing" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Waterproofing"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.8</span> <span>Waterproofing</span> </div> </a> <ul id="toc-Waterproofing-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Duct_system_components" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Duct_system_components"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Duct system components</span> </div> </a> <button aria-controls="toc-Duct_system_components-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Duct system components subsection</span> </button> <ul id="toc-Duct_system_components-sublist" class="vector-toc-list"> <li id="toc-Vibration_isolators" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Vibration_isolators"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.1</span> <span>Vibration isolators</span> </div> </a> <ul id="toc-Vibration_isolators-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Take-offs" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Take-offs"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2</span> <span>Take-offs</span> </div> </a> <ul id="toc-Take-offs-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Stack_boots_and_heads" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Stack_boots_and_heads"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.3</span> <span>Stack boots and heads</span> </div> </a> <ul id="toc-Stack_boots_and_heads-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Volume_control_dampers" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Volume_control_dampers"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.4</span> <span>Volume control dampers</span> </div> </a> <ul id="toc-Volume_control_dampers-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Smoke_and_fire_dampers" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Smoke_and_fire_dampers"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.5</span> <span>Smoke and fire dampers</span> </div> </a> <ul id="toc-Smoke_and_fire_dampers-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Turning_vanes" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Turning_vanes"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.6</span> <span>Turning vanes</span> </div> </a> <ul id="toc-Turning_vanes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Plenums" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Plenums"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.7</span> <span>Plenums</span> </div> </a> <ul id="toc-Plenums-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Terminal_units" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Terminal_units"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.8</span> <span>Terminal units</span> </div> </a> <ul id="toc-Terminal_units-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Air_terminals" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Air_terminals"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.9</span> <span>Air terminals</span> </div> </a> <ul id="toc-Air_terminals-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Duct_cleaning" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Duct_cleaning"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Duct cleaning</span> </div> </a> <button aria-controls="toc-Duct_cleaning-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Duct cleaning subsection</span> </button> <ul id="toc-Duct_cleaning-sublist" class="vector-toc-list"> <li id="toc-Signs_and_indicators" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Signs_and_indicators"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Signs and indicators</span> </div> </a> <ul id="toc-Signs_and_indicators-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Commercial_inspection" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Commercial_inspection"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Commercial inspection</span> </div> </a> <ul id="toc-Commercial_inspection-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Duct_sealing" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Duct_sealing"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Duct sealing</span> </div> </a> <button aria-controls="toc-Duct_sealing-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Duct sealing subsection</span> </button> <ul id="toc-Duct_sealing-sublist" class="vector-toc-list"> <li id="toc-Signs_of_leaks" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Signs_of_leaks"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>Signs of leaks</span> </div> </a> <ul id="toc-Signs_of_leaks-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" 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<div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. 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class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/L%C3%BCftungskanal" title="Lüftungskanal – German" lang="de" hreflang="de" data-title="Lüftungskanal" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Conducto_de_aire" title="Conducto de aire – Spanish" lang="es" hreflang="es" data-title="Conducto de aire" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%DA%A9%D8%A7%D9%86%D8%A7%D9%84_%D9%87%D9%88%D8%A7" title="کانال هوا – Persian" lang="fa" hreflang="fa" data-title="کانال هوا" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Air_duct" title="Air duct – French" lang="fr" hreflang="fr" data-title="Air duct" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Zrakovod" title="Zrakovod – Croatian" lang="hr" hreflang="hr" data-title="Zrakovod" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Canalizzazioni_aerauliche" title="Canalizzazioni aerauliche – Italian" lang="it" hreflang="it" data-title="Canalizzazioni aerauliche" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Luchtkoker" title="Luchtkoker – Dutch" lang="nl" hreflang="nl" data-title="Luchtkoker" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%83%80%E3%82%AF%E3%83%88" title="ダクト – Japanese" lang="ja" hreflang="ja" data-title="ダクト" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9A%D0%B0%D0%BD%D0%B0%D0%BB%D1%8C%D0%BD%D1%8B%D0%B9_%D0%BA%D0%BE%D0%BD%D0%B4%D0%B8%D1%86%D0%B8%D0%BE%D0%BD%D0%B5%D1%80" title="Канальный кондиционер – Russian" lang="ru" hreflang="ru" data-title="Канальный 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id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Conduit used in heating, ventilation, and air conditioning</div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Regenerative_thermal_oxidizer.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/f8/Regenerative_thermal_oxidizer.jpg/220px-Regenerative_thermal_oxidizer.jpg" decoding="async" width="220" height="124" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/f8/Regenerative_thermal_oxidizer.jpg/330px-Regenerative_thermal_oxidizer.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/f8/Regenerative_thermal_oxidizer.jpg/440px-Regenerative_thermal_oxidizer.jpg 2x" data-file-width="1632" data-file-height="918" /></a><figcaption>Ducts for air pollution control in a 17000 <a href="/wiki/Scfm" class="mw-redirect" title="Scfm">standard cubic feet per minute</a> <a href="/wiki/Regenerative_thermal_oxidiser" class="mw-redirect" title="Regenerative thermal oxidiser">regenerative thermal oxidizer (RTO).</a></figcaption></figure> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Central_ventilation_tube2.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/0/01/Central_ventilation_tube2.jpg" decoding="async" width="250" height="167" class="mw-file-element" data-file-width="250" data-file-height="167" /></a><figcaption>A round galvanized steel duct connecting to a typical <a href="/wiki/Diffuser_(thermodynamics)" title="Diffuser (thermodynamics)">diffuser</a></figcaption></figure> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Shaft_dupont_mississauga_on.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/2f/Shaft_dupont_mississauga_on.jpg/220px-Shaft_dupont_mississauga_on.jpg" decoding="async" width="220" height="160" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/2f/Shaft_dupont_mississauga_on.jpg/330px-Shaft_dupont_mississauga_on.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/2f/Shaft_dupont_mississauga_on.jpg/440px-Shaft_dupont_mississauga_on.jpg 2x" data-file-width="4875" data-file-height="3540" /></a><figcaption><a href="/wiki/Fire-resistance_rating" title="Fire-resistance rating">Fire-resistance rated</a> mechanical shaft with HVAC <a href="/wiki/Sheet_metal" title="Sheet metal">sheet metal</a> ducting and <a href="/wiki/Copper" title="Copper">copper</a> <a href="/wiki/Pipe_(material)" class="mw-redirect" title="Pipe (material)">piping</a>, as well as <a href="/wiki/Joint_(building)" title="Joint (building)">"HOW" (Head-Of-Wall) joint</a> between top of <a href="/wiki/Concrete" title="Concrete">concrete</a> block wall and underside of concrete slab, <a href="/wiki/Firestop" title="Firestop">firestopped</a> with ceramic fibre-based firestop <a href="/wiki/Caulking" class="mw-redirect" title="Caulking">caulking</a> on top of <a href="/wiki/Mineral_wool" title="Mineral wool">rockwool</a>.</figcaption></figure> <p><b>Ducts</b> are conduits or passages used in <a href="/wiki/HVAC" class="mw-redirect" title="HVAC">heating, ventilation, and air conditioning</a> (HVAC) to deliver and remove air. The needed airflows include, for example, <i>supply air</i>, <i>return air</i>, and <i>exhaust air</i>.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> Ducts commonly also deliver <i><a href="/wiki/Ventilation_(architecture)" title="Ventilation (architecture)">ventilation air</a></i> as part of the supply air. As such, air ducts are one method of ensuring acceptable <a href="/wiki/Indoor_air_quality" title="Indoor air quality">indoor air quality</a> as well as <a href="/wiki/Thermal_comfort" title="Thermal comfort">thermal comfort</a>. </p><p>A duct system is also called <i>ductwork</i>. Planning (laying out), sizing, optimizing, detailing, and finding the pressure losses through a duct system is called <i>duct design</i>.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Materials">Materials</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=1" title="Edit section: Materials"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Ducts can be made out of the following materials: They are </p> <div class="mw-heading mw-heading3"><h3 id="Galvanized_steel">Galvanized steel</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=2" title="Edit section: Galvanized steel"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Galvanized" class="mw-redirect" title="Galvanized">Galvanized</a> <a href="/wiki/Mild_steel" class="mw-redirect" title="Mild steel">mild steel</a> is the standard and most common material used in fabricating ductwork because the zinc coating of this metal prevents rusting and avoids cost of painting. For insulation purposes, metal ducts are typically lined with faced <a href="/wiki/Fiberglass" title="Fiberglass">fiberglass</a> blankets (duct liner) or wrapped externally with fiberglass blankets (duct wrap). When necessary, a double walled duct is used. This will usually have an inner perforated liner, then a 1–2" (2.5-5 cm) layer of fiberglass insulation contained inside an outer solid pipe. </p><p>Rectangular ductwork commonly is fabricated to suit by specialized metal shops. For ease of handling, it most often comes in 4' (120 cm) sections (or joints). Round duct is made using a continuous spiral forming machine which can make round duct in nearly any diameter when using the right forming die and to any length to suit, but the most common stock sizes range evenly from 4" to 24" (10-60 cm) with 6"-12" (15-30 cm) being most commonly used. Stock pipe is usually sold in 10' (300 cm) joints. There are also 5' (150 cm) joints of the non-spiral type pipe available, which is commonly used in residential applications. </p> <div class="mw-heading mw-heading3"><h3 id="Aluminium">Aluminium</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=3" title="Edit section: Aluminium"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Aluminium" title="Aluminium">Aluminium</a> ductwork is lightweight and quick to install. Also, custom or special shapes of ducts can be easily fabricated in the shop or on site. </p><p>The ductwork construction starts with the tracing of the duct outline onto the aluminium preinsulated panel. The parts are then typically cut at 45°, bent if required to obtain the different fittings (i.e. elbows, tapers) and finally assembled with glue. Aluminium tape is applied to all seams where the external surface of the aluminium foil has been cut. A variety of flanges are available to suit various installation requirements. All internal joints are sealed with sealant. </p><p>Aluminum is also used to make round spiral duct, but it is much less common than galvanized steel. </p> <div class="mw-heading mw-heading3"><h3 id="Polyurethane_and_phenolic_insulation_panels_(pre-insulated_air_ducts)"><span id="Polyurethane_and_phenolic_insulation_panels_.28pre-insulated_air_ducts.29"></span>Polyurethane and phenolic insulation panels (pre-insulated air ducts)</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=4" title="Edit section: Polyurethane and phenolic insulation panels (pre-insulated air ducts)"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Traditionally, air ductwork is made of sheet metal which was installed first and then lagged with insulation. Today, a sheet metal fabrication shop would commonly fabricate the galvanized steel duct and insulate with duct wrap prior to installation. However, ductwork manufactured from rigid insulation panels does not need any further insulation and can be installed in a single step. Both <a href="/wiki/Polyurethane" title="Polyurethane">polyurethane</a> and <a href="/wiki/Phenol_formaldehyde_resin" title="Phenol formaldehyde resin">phenolic foam</a> panels are manufactured with factory applied aluminium facings on both sides. The thickness of the aluminium foil can vary from 25 micrometres for indoor use to 200 micrometers for external use or for higher mechanical characteristics. There are various types of rigid polyurethane foam panels available, including water formulated panel for which the foaming process is obtained through the use of water and CO<sub>2</sub> instead of <a href="/wiki/Chlorofluorocarbon" title="Chlorofluorocarbon">CFC</a>, <a href="/wiki/Chlorofluorocarbon" title="Chlorofluorocarbon">HCFC</a>, <a href="/wiki/Hydrofluorocarbon" title="Hydrofluorocarbon">HFC</a> and <a href="/wiki/Hydrocarbon" title="Hydrocarbon">HC</a> gasses. Most manufacturers of rigid polyurethane or phenolic foam panels use <a href="/wiki/Pentane" title="Pentane">pentane</a> as <a href="/wiki/Foaming_agent" title="Foaming agent">foaming agent</a> instead of the aforementioned gasses. </p><p>A rigid phenolic insulation ductwork system is listed as a class 1<sup class="noprint Inline-Template" style="margin-left:0.1em; white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Please_clarify" title="Wikipedia:Please clarify"><span title="The text near this tag may need clarification or removal of jargon. (July 2014)">clarification needed</span></a></i>]</sup> air duct to UL 181 Standard for Safety. </p> <div class="mw-heading mw-heading3"><h3 id="Fiberglass_duct_board_(preinsulated_non-metallic_ductwork)"><span id="Fiberglass_duct_board_.28preinsulated_non-metallic_ductwork.29"></span>Fiberglass duct board (preinsulated non-metallic ductwork)</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=5" title="Edit section: Fiberglass duct board (preinsulated non-metallic ductwork)"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Fiberglass duct board panels provide built-in <a href="/wiki/Thermal_insulation" title="Thermal insulation">thermal insulation</a> and the interior surface absorbs [sound], helping to provide quiet operation of the HVAC system. </p><p>The duct board is formed by sliding a specially-designed <a href="/wiki/Knife" title="Knife">knife</a> along the board using a straightedge as a guide. The knife automatically trims out a groove with 45° sides which does not quite penetrate the entire depth of the duct board, thus providing a thin section acting as a <a href="/wiki/Hinge" title="Hinge">hinge</a>. The duct board can then be folded along the groove to produce 90° folds, making the rectangular duct shape in the fabricator's desired size. The duct is then closed with outward-clinching staples and special aluminum or similar metal-backed tape. </p> <div class="mw-heading mw-heading3"><h3 id="Flexible_ducting">Flexible ducting</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=6" title="Edit section: Flexible ducting"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Flexible ducts (also known as <i>flex</i>) are typically made of flexible plastic over a metal wire coil to shape a tube. They have a variety of configurations. In the United States, the insulation is usually <a href="/wiki/Glass_wool" title="Glass wool">glass wool</a>, but other markets such as Australia, use both <a href="/wiki/Polyester" title="Polyester">polyester</a> fiber and glass wool for thermal insulation. A protective layer surrounds the insulation, and is usually composed of <a href="/wiki/Polyethylene" title="Polyethylene">polyethylene</a> or metalized <a href="/wiki/Polyethylene_terephthalate" title="Polyethylene terephthalate">PET</a>. It is commonly sold as boxes containing 25' (7.5 m) of duct compressed into a 5' (1.5 m) length. It is available in diameters ranging from as small as 4" (10 cm) to as big as 18" (45 cm), but the most commonly used are even sizes ranging from 6" to 12" (15 to 30 cm). </p><p>Flexible duct is very convenient for attaching supply air outlets to the rigid ductwork. It is commonly attached with long zip ties or metal band claps. However, the pressure loss is higher than for most other types of ducts. As such, designers and installers attempt to keep their installed lengths (<i>runs</i>) short, e.g. less than 15 feet (5 m) or so, and try to minimize turns. Kinks in flexible ducting must be avoided. Some flexible duct markets prefer to avoid using flexible duct on the return air portions of HVAC systems, however flexible duct can tolerate moderate <a href="https://en.wiktionary.org/wiki/negative_pressure" class="extiw" title="wikt:negative pressure">negative pressures</a>. The UL181 test requires a negative pressure of 200 Pa. </p><p>To use flexible ducting in a system, make sure to pull the duct tight so you get the full internal diameter. This reduces resistance and improves airflow, as well as ventilation efficiency. Minimize bends and kinks as much as possible, since they can affect how well the airstream flows through the ductwork. </p><p>There are a few types of flexible ducting - Polyurethane (PU), Aluminium & Aluminium insulated, Acoustic and Rectangular flexible ducting, as well as semi- and combi-flex. </p> <div class="mw-heading mw-heading3"><h3 id="Fabric_ducting">Fabric ducting</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=7" title="Edit section: Fabric ducting"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>This is actually an air distribution device and is not intended as a conduit for conditioned air. The term fabric <i>duct</i> is therefore somewhat misleading; <i>fabric air dispersion system</i> would be the more definitive name. However, as it often replaces hard ductwork, it is easy to perceive it simply as a duct. Usually made of polyester material, fabric ducts can provide a more even distribution and blending of the conditioned air in a given space than a conventional duct system. They may also be manufactured with vents or orifices. </p><p>Fabric ducts are available in various colors, with options for silk screening or other forms of decoration, or in porous (air-permeable) and non-porous fabric. The determination which fabric is appropriate (i.e. air-permeable or not) can be made by considering if the application would require an insulated metal duct. If so, an air-permeable fabric is recommended because it will not commonly create condensation on its surface and can therefore be used where air is supplied below the <a href="/wiki/Dew_point" title="Dew point">dew point</a>. Material that eliminates moisture may be healthier for the occupants. It can also be treated with an anti-microbial agent to inhibit bacterial growth. Porous material also tends to require less maintenance as it repels dust and other airborne contaminants. </p><p>Fabric made of more than 50% recycled material is also available, allowing it to be certified as green product. The material can also be <a href="/wiki/Fire_retardant" title="Fire retardant">fire retardant</a>, which means that the fabric can still burn, but will extinguish when the heat source is removed. </p><p>Fabric ducts are not rated for use in ceilings or concealed attic spaces. However, products for use in <a href="/wiki/Raised_floor" title="Raised floor">raised floor</a> applications are available. Fabric ducting usually weighs less than other conventional ducting and will therefore put less stress on the building's structure. The lower weight allows for easier installation. </p><p>Fabric ducts require a minimum of certain range of airflow and static pressure in order for it to work. </p> <div class="mw-heading mw-heading3"><h3 id="PVC_low-profile_ducting">PVC low-profile ducting</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=8" title="Edit section: PVC low-profile ducting"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Polyvinyl_chloride" title="Polyvinyl chloride">PVC</a> low-profile ducting has been developed as a cost-effective alternative to steel low-profile ducting. Low-profile ducting has been used extensively in apartment and hotel ventilation since 2005. The growth of low-profile ducting has grown significantly due to the reduction of available space in ceiling cavities in an effort to reduce cost. Since the <a href="/wiki/Grenfell_Tower_fire" title="Grenfell Tower fire">Grenfell Tower fire</a> in 2017 there has been a rise in the discovery of non-compliant building materials; many PVC low-profile ducting manufacturers have struggled to gain or maintain compliance, and some building projects have had to resort back to using the more expensive steel option. </p> <div class="mw-heading mw-heading3"><h3 id="Waterproofing">Waterproofing</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=9" title="Edit section: Waterproofing"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The finish for external ductwork exposed to the weather can be sheet steel coated with aluminium or an aluminium/zinc alloy, a multilayer laminate, a fibre reinforced polymer or other waterproof coating. </p> <div class="mw-heading mw-heading2"><h2 id="Duct_system_components">Duct system components</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=10" title="Edit section: Duct system components"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Besides the ducts themselves, complete ducting systems contain many other components. </p> <div class="mw-heading mw-heading3"><h3 id="Vibration_isolators">Vibration isolators</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=11" title="Edit section: Vibration isolators"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Air_handling_unit.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/00/Air_handling_unit.JPG/220px-Air_handling_unit.JPG" decoding="async" width="220" height="146" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/00/Air_handling_unit.JPG/330px-Air_handling_unit.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/00/Air_handling_unit.JPG/440px-Air_handling_unit.JPG 2x" data-file-width="1109" data-file-height="738" /></a><figcaption>An air handling unit with vibration isolator (3)</figcaption></figure> <p>A duct system often begins at an <a href="/wiki/Air_handler" title="Air handler">air handler</a>. The <a href="/wiki/Fan_(mechanical)" class="mw-redirect" title="Fan (mechanical)">blowers</a> in the air handler can create substantial <a href="/wiki/Vibration" title="Vibration">vibration</a>, and the large area of the duct system would transmit this <a href="/wiki/Noise" title="Noise">noise</a> and vibration to the inhabitants of the building. To avoid this, vibration isolators (flexible sections) are normally inserted into the duct immediately before and after the air handler. The rubberized canvas-like material of these sections allows the air handler to vibrate without transmitting much vibration to the attached ducts. The same flexible section can reduce the noise that can occur when the blower engages and positive air pressure is introduced to the ductwork. </p> <div class="mw-heading mw-heading3"><h3 id="Take-offs">Take-offs</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=12" title="Edit section: Take-offs"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Downstream of the air handler, the supply air <i>trunk duct</i> will commonly fork, providing air to many individual air outlets such as <a href="/wiki/Diffuser_(thermodynamics)" title="Diffuser (thermodynamics)">diffusers</a>, grilles, and <a href="/wiki/Register_(air_and_heating)" title="Register (air and heating)">registers</a>. When the system is designed with a main duct branching into many subsidiary branch ducts, fittings called <i>take-offs</i> allow a small portion of the flow in the main duct to be diverted into each branch duct. Take-offs may be fitted into round or rectangular openings cut into the wall of the main duct. The take-off commonly has many small metal tabs that are then bent to attach the take-off to the main duct. Round versions are called <i>spin-in fittings</i>. Other take-off designs use a snap-in attachment method, sometimes coupled with an adhesive foam gasket for improved sealing. The outlet of the take-off then connects to the rectangular, oval, or round branch duct. </p> <div class="mw-heading mw-heading3"><h3 id="Stack_boots_and_heads">Stack boots and heads</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=13" title="Edit section: Stack boots and heads"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Ducts, especially in homes, must often allow air to travel vertically within relatively thin walls. These vertical ducts are called <i>stacks</i> and are formed with either very wide and relatively thin rectangular sections or oval sections. At the bottom of the stack, a <i>stack boot</i> provides a transition from an ordinary large round or rectangular duct to the thin wall-mounted duct. At the top, a <i>stack head</i> can provide a transition back to ordinary ducting while a <i>register head</i> allows the transition to a wall-mounted air register. </p> <div class="mw-heading mw-heading3"><h3 id="Volume_control_dampers">Volume control dampers</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=14" title="Edit section: Volume control dampers"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Zone_Damper_1.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Zone_Damper_1.jpg/220px-Zone_Damper_1.jpg" decoding="async" width="220" height="123" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Zone_Damper_1.jpg/330px-Zone_Damper_1.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Zone_Damper_1.jpg/440px-Zone_Damper_1.jpg 2x" data-file-width="1419" data-file-height="792" /></a><figcaption>An opposed-blade, motor-operated zone damper, shown in the "open" position.</figcaption></figure> <p>Ducting systems must often provide a method of adjusting the volume of air flow to various parts of the system. Volume control dampers (VCDs; not to be confused with smoke/fire dampers) provide this function. Besides the regulation provided at the registers or diffusers that spread air into individual rooms, <a href="/wiki/Damper_(architecture)" class="mw-redirect" title="Damper (architecture)">dampers</a> can be fitted within the ducts themselves. These dampers may be manual or automatic. <a href="/wiki/Zone_damper" class="mw-redirect" title="Zone damper">Zone dampers</a> provide automatic control in simple systems while <a href="/wiki/Variable_air_volume" title="Variable air volume">variable air volume</a> (VAV) allows control in sophisticated systems. </p> <div class="mw-heading mw-heading3"><h3 id="Smoke_and_fire_dampers">Smoke and fire dampers</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=15" title="Edit section: Smoke and fire dampers"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Smoke_damper" title="Smoke damper">Smoke dampers</a> and <a href="/wiki/Fire_damper" title="Fire damper">fire dampers</a> are found in ductwork where the duct passes through a <a href="/wiki/Firewall_(construction)" title="Firewall (construction)">firewall</a> or firecurtain. </p><p>Smoke dampers are driven by a motor, referred to as an <a href="/wiki/Actuator" title="Actuator">actuator</a>. A probe connected to the motor is installed in the run of the duct and detects smoke, either in the air which has been extracted from or is being supplied to a room, or elsewhere within the run of the duct. Once smoke is detected, the actuator will automatically close the smoke damper until it is manually re-opened. </p><p>Fire dampers can be found in the same places as smoke dampers, depending on the application of the area after the firewall. Unlike smoke dampers, they are not triggered by any electrical system (which is an advantage in case of an electrical failure where the smoke dampers would fail to close). Vertically mounted fire dampers are gravity operated, while horizontal fire dampers are spring powered. A fire damper's most important feature is a mechanical <a href="/wiki/Fusible_link" title="Fusible link">fusible link</a> which is a piece of metal that will melt or break at a specified temperature. This allows the damper to close (either from gravity or spring power), effectively sealing the duct, containing the fire, and blocking the necessary air to burn. </p> <div class="mw-heading mw-heading3"><h3 id="Turning_vanes">Turning vanes</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=16" title="Edit section: Turning vanes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Turning_vanes_inside_of_large_durasteel_ductwork_06.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/54/Turning_vanes_inside_of_large_durasteel_ductwork_06.png/170px-Turning_vanes_inside_of_large_durasteel_ductwork_06.png" decoding="async" width="170" height="256" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/54/Turning_vanes_inside_of_large_durasteel_ductwork_06.png/255px-Turning_vanes_inside_of_large_durasteel_ductwork_06.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/54/Turning_vanes_inside_of_large_durasteel_ductwork_06.png/340px-Turning_vanes_inside_of_large_durasteel_ductwork_06.png 2x" data-file-width="3084" data-file-height="4644" /></a><figcaption>Turning vanes inside of large <a href="/wiki/Fire-resistance_rating" title="Fire-resistance rating">fire-resistance rated</a> <a class="external text" href="https://commons.wikimedia.org/wiki/Category:Durasteel">Durasteel</a> <a href="/wiki/Pressurisation_ductwork" title="Pressurisation ductwork">pressurisation ductwork</a></figcaption></figure> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Turning_vanes_inside_of_large_durasteel_ductwork_11.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/52/Turning_vanes_inside_of_large_durasteel_ductwork_11.png/220px-Turning_vanes_inside_of_large_durasteel_ductwork_11.png" decoding="async" width="220" height="146" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/52/Turning_vanes_inside_of_large_durasteel_ductwork_11.png/330px-Turning_vanes_inside_of_large_durasteel_ductwork_11.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/52/Turning_vanes_inside_of_large_durasteel_ductwork_11.png/440px-Turning_vanes_inside_of_large_durasteel_ductwork_11.png 2x" data-file-width="4644" data-file-height="3084" /></a><figcaption>Turning vane close-up.</figcaption></figure> <p><a href="/wiki/HVAC_turning_vanes" class="mw-redirect" title="HVAC turning vanes">Turning vanes</a> are installed inside of ductwork at changes of direction (e.g. at 90° turns) in order to minimize turbulence and resistance to the air flow. The vanes guide the air so it can follow the change of direction more easily. </p> <div class="mw-heading mw-heading3"><h3 id="Plenums">Plenums</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=17" title="Edit section: Plenums"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Air-mixing_plenum" title="Air-mixing plenum">Plenums</a> are the central distribution and collection units for an HVAC system. The return plenum carries the air from several large return <a href="/wiki/Grille_(car)" title="Grille (car)">grilles</a> (vents) or <a href="/wiki/Bell_mouth" title="Bell mouth">bell mouths</a> to a central air handler. The supply plenum directs air from the central unit to the rooms which the system is designed to heat or cool. They must be carefully planned in ventilation design.<sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Please_clarify" title="Wikipedia:Please clarify"><span title="The reason for this is unclear. (July 2014)">why?</span></a></i>]</sup> </p> <div class="mw-heading mw-heading3"><h3 id="Terminal_units">Terminal units</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=18" title="Edit section: Terminal units"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>While single-zone <a href="/wiki/Constant_air_volume" title="Constant air volume">constant air volume</a> systems typically do not have these, multi-zone systems often have terminal units in the branch ducts. Usually there is one terminal unit per <a href="/w/index.php?title=Thermal_zone&action=edit&redlink=1" class="new" title="Thermal zone (page does not exist)">thermal zone</a>. Some types of terminal units are <a href="/wiki/Variable_air_volume" title="Variable air volume">VAV</a> boxes (single or dual duct), fan-powered mixing boxes (in parallel or series arrangement), and induction terminal units. Terminal units may also include a heating or cooling coil. </p> <div class="mw-heading mw-heading3"><h3 id="Air_terminals">Air terminals</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=19" title="Edit section: Air terminals"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Air terminals are the supply air outlets and return or exhaust air inlets. For supply, <a href="/wiki/Diffuser_(thermodynamics)" title="Diffuser (thermodynamics)">diffusers</a> are most common, but <a href="/wiki/Grille_(architecture)" title="Grille (architecture)">grilles</a>, and for very small HVAC systems (such as in residences) <a href="/wiki/Register_(air_and_heating)" title="Register (air and heating)">registers</a> are also used widely. Return or exhaust grilles are used primarily for appearance reasons, but some also incorporate an air filter and are known as filter returns.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Duct_cleaning">Duct cleaning</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=20" title="Edit section: Duct cleaning"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The position of the <a href="/wiki/U.S._Environmental_Protection_Agency" class="mw-redirect" title="U.S. Environmental Protection Agency">U.S. Environmental Protection Agency</a> (EPA) is that "If no one in your household suffers from allergies or unexplained symptoms or illnesses and if, after a visual inspection of the inside of the ducts, you see no indication that your air ducts are contaminated with large deposits of dust or mold (no musty odor or visible mold growth), having your air ducts cleaned is probably unnecessary."<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Manual_of_Style/Dates_and_numbers#Chronological_items" title="Wikipedia:Manual of Style/Dates and numbers"><span title="The date of the event predicted near this tag has passed. (September 2024)">needs update</span></a></i>]</sup><sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Accuracy_dispute#Disputed_statement" title="Wikipedia:Accuracy dispute"><span title="The material near this tag is possibly inaccurate or nonfactual. (September 2024)">dubious</span></a> – <a href="/wiki/Talk:Duct_(flow)#Dubious" title="Talk:Duct (flow)">discuss</a></i>]</sup> </p><p>A thorough duct cleaning done by a professional duct cleaner will remove <a href="/wiki/Dust" title="Dust">dust</a>, <a href="/wiki/Cobwebs" class="mw-redirect" title="Cobwebs">cobwebs</a>, <a href="/wiki/Debris" title="Debris">debris</a>, pet hair, <a href="/wiki/Rodent" title="Rodent">rodent</a> hair and droppings, paper clips, <a href="/wiki/Calcium" title="Calcium">calcium</a> deposits, children's <a href="/wiki/Toys" class="mw-redirect" title="Toys">toys</a>, and whatever else might collect inside. Ideally, the interior surface will be shiny and bright after cleaning. Insulated fiber glass duct liner and duct board can be cleaned with special non-metallic bristles. Fabric ducting can be washed or vacuumed using typical household appliances. </p> <div class="mw-heading mw-heading3"><h3 id="Signs_and_indicators">Signs and indicators</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=21" title="Edit section: Signs and indicators"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Cleaning of the duct system may be necessary if: </p> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-More_citations_needed_section plainlinks metadata ambox ambox-content ambox-Refimprove" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></span></div></td><td class="mbox-text"><div class="mbox-text-span">This section <b>needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a></b>.<span class="hide-when-compact"> Please help <a href="/wiki/Special:EditPage/Duct_(flow)" title="Special:EditPage/Duct (flow)">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a> in this section. Unsourced material may be challenged and removed.</span> <span class="date-container"><i>(<span class="date">July 2009</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <ul><li>Sweeping and dusting the furniture needs to be done more than usual.</li> <li>After cleaning, there is still left over visible dust floating around the house.</li> <li>After or during sleep, occupants experience headaches, nasal congestion, or other sinus problems.</li> <li>Rooms in the house have little or no air flow coming from the vents.</li> <li>Occupants are constantly getting sick or are experiencing more allergies than usual.</li> <li>There is a musty or stale odor when turning on the furnace or air conditioner.</li> <li>Occupants are experiencing signs of sickness, e.g. fatigue, headache, sneezing, stuffy or running nose, irritability, nausea, dry or burning sensation in eyes, nose and throat.</li></ul> <div class="mw-heading mw-heading3"><h3 id="Commercial_inspection">Commercial inspection</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=22" title="Edit section: Commercial inspection"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In commercial settings, regular inspection of ductwork is recommended by several standards. One standard recommends inspecting supply ducts every 1–2 years, return ducts every 1–2 years, and air handling units annually.<sup id="cite_ref-NADCA_5-0" class="reference"><a href="#cite_note-NADCA-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> Another recommends visual inspection of internally lined ducts annually<sup id="cite_ref-ASH180_6-0" class="reference"><a href="#cite_note-ASH180-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> Duct cleaning should be based on the results of those inspections. </p><p>Inspections are typically visual, looking for water damage or biological growth.<sup id="cite_ref-NADCA_5-1" class="reference"><a href="#cite_note-NADCA-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-ASH180_6-1" class="reference"><a href="#cite_note-ASH180-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Willis_7-0" class="reference"><a href="#cite_note-Willis-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> When visual inspection needs to be validated numerically, a <i>vacuum test</i> (VT) or <i>deposit thickness test</i> (DTT) can be performed. A duct with less than 0.75 mg/100m<sup>2</sup> is considered to be clean, per the NADCA standard.<sup id="cite_ref-Willis_7-1" class="reference"><a href="#cite_note-Willis-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> A Hong Kong standard lists surface deposit limits of 1g/m<sup>2</sup> for supply and return ducts and 6g/m<sup>2</sup> for exhaust ducts, or a maximum deposit thickness of 60 μm in supply and return ducts, and 180 μm for exhaust ducts.<sup id="cite_ref-AIIB_8-0" class="reference"><a href="#cite_note-AIIB-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> In the UK, <a href="/wiki/Chartered_Institution_of_Building_Services_Engineers" title="Chartered Institution of Building Services Engineers">CIBSE</a> standard TM26 recommends duct cleaning if measured bacterial content is more than 29 colony forming units (CFU) per 10 cm<sup>2</sup>; contamination is classified as "low" below 10 CFU/cm<sup>2</sup>, "medium" at up to 20 CFU/cm<sup>2</sup>, and "high" when measured above 20 CFU/cm<sup>2</sup>.<sup id="cite_ref-CIBSE26_9-0" class="reference"><a href="#cite_note-CIBSE26-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Duct_sealing">Duct sealing</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=23" title="Edit section: Duct sealing"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Air pressure combined with air duct leakage can lead to a loss of energy in a <a href="/wiki/HVAC" class="mw-redirect" title="HVAC">HVAC</a> system. Sealing leaks in air ducts reduces air leakage, optimizes energy efficiency, and controls the entry of pollutants into the building. Before sealing ducts it is imperative to ensure the total external static pressure of the duct work, and if equipment will fall within the equipment manufacturer's specifications. If not, higher energy usage and reduced equipment performance may result. </p><p>Commonly available <a href="/wiki/Duct_tape" title="Duct tape">duct tape</a> should not be used on air ducts (metal, fiberglass, or otherwise) that are intended for long-term use. The adhesive on so called duct tape dries and releases with time. A more common type of duct sealant is a water-based paste that is brushed or sometimes sprayed on the seams when the duct is built. <a href="/wiki/Building_code" title="Building code">Building codes</a> and UL standards call for special fire-resistant tapes, often with foil backings and long lasting adhesives. </p><p>Automated technology exists that can seal a duct system in its entirety from the inside out using a patented process and specialized sealant. This method for duct sealing is often used in commercial construction and multi-unit residential construction. The cost associated with automated duct sealing often makes it impractical for the average homeowner to implement in their own house. </p> <div class="mw-heading mw-heading3"><h3 id="Signs_of_leaks">Signs of leaks</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=24" title="Edit section: Signs of leaks"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Signs of leaky or poorly performing air ducts include: </p> <ul><li>Utility bills in winter and summer months above average relative to rate fluctuation</li> <li>Spaces or rooms that are difficult to heat or cool</li> <li>Duct location in an attic, attached garage, leaky floor cavity, crawl space or unheated basement.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup></li></ul> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=25" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);display:flow-root}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 0.9em 2px 0;text-align:center}@media(min-width:500px){.mw-parser-output .side-box-flex{display:flex;align-items:center}.mw-parser-output .side-box-text{flex:1;min-width:0}}@media(min-width:720px){.mw-parser-output .side-box{width:238px}.mw-parser-output .side-box-right{clear:right;float:right;margin-left:1em}.mw-parser-output .side-box-left{margin-right:1em}}</style><style data-mw-deduplicate="TemplateStyles:r1237033735">@media print{body.ns-0 .mw-parser-output .sistersitebox{display:none!important}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}</style><div class="side-box side-box-right plainlinks sistersitebox"><style data-mw-deduplicate="TemplateStyles:r1126788409">.mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0}</style> <div class="side-box-flex"> <div class="side-box-image"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png" decoding="async" width="30" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/45px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/59px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></span></span></div> <div class="side-box-text plainlist">Wikimedia Commons has media related to <a href="https://commons.wikimedia.org/wiki/Category:Ductwork" class="extiw" title="commons:Category:Ductwork"><span style="font-style:italic; font-weight:bold;">Ductwork</span></a>.</div></div> </div> <ul><li><a href="/wiki/Central_vacuum_cleaner" title="Central vacuum cleaner">Central vacuum cleaner</a></li> <li><a href="/wiki/Duct_(industrial_exhaust)" title="Duct (industrial exhaust)">Duct (industrial exhaust)</a></li> <li><a href="/wiki/Darcy_friction_factor" class="mw-redirect" title="Darcy friction factor">Darcy friction factor</a></li> <li><a href="/wiki/Fire_damper" title="Fire damper">Fire damper</a></li> <li><a href="/wiki/HVAC" class="mw-redirect" title="HVAC">HVAC</a></li> <li><a href="/wiki/Bus_duct" title="Bus duct">Bus duct</a></li> <li><a href="/wiki/Pressurisation_ductwork" title="Pressurisation ductwork">Pressurisation ductwork</a></li> <li><a href="/wiki/Register_(air_and_heating)" title="Register (air and heating)">Register (air and heating)</a></li> <li><a href="/wiki/Smoke_exhaust_ductwork" title="Smoke exhaust ductwork">Smoke exhaust ductwork</a></li> <li><a href="/wiki/Sheet_Metal_and_Air_Conditioning_Contractors%27_National_Association" title="Sheet Metal and Air Conditioning Contractors' National Association">Sheet Metal and Air Conditioning Contractors' National Association</a></li> <li><a href="/wiki/Uniform_Mechanical_Code" title="Uniform Mechanical Code">Uniform Mechanical Code</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=26" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text">The Fundamentals volume of the <i><a href="/wiki/ASHRAE_Handbook" title="ASHRAE Handbook">ASHRAE Handbook</a></i>, <a href="/wiki/ASHRAE" title="ASHRAE">ASHRAE</a>, Inc., Atlanta, GA, USA, 2005</span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><i>HVAC Systems – Duct Design</i>, 3rd Ed., <a href="/wiki/SMACNA" class="mw-redirect" title="SMACNA">SMACNA</a>, 1990</span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><i>Designer's Guide to Ceiling-Based Room Air Diffusion</i>, Rock and Zhu, <a href="/wiki/ASHRAE" title="ASHRAE">ASHRAE</a>, Inc., Atlanta, GA, USA, 2002</span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFUS_EPA2014" class="citation web cs1">US EPA, OAR (2014-07-28). <a rel="nofollow" class="external text" href="https://www.epa.gov/indoor-air-quality-iaq/should-you-have-air-ducts-your-home-cleaned">"Should You Have the Air Ducts in Your Home Cleaned?"</a>. <i>www.epa.gov</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2022-11-23</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.epa.gov&rft.atitle=Should+You+Have+the+Air+Ducts+in+Your+Home+Cleaned%3F&rft.date=2014-07-28&rft.aulast=US+EPA&rft.aufirst=OAR&rft_id=https%3A%2F%2Fwww.epa.gov%2Findoor-air-quality-iaq%2Fshould-you-have-air-ducts-your-home-cleaned&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADuct+%28flow%29" class="Z3988"></span></span> </li> <li id="cite_note-NADCA-5"><span class="mw-cite-backlink">^ <a href="#cite_ref-NADCA_5-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NADCA_5-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFNADCA2013" class="citation web cs1">NADCA (2013). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20150211205954/http://www.ductandvent.com/clientuploads/NADCA-13-ACRbooklet_final.pdf">"ACR, The NADCA Standard for Assessment Cleaning Restoration of HVAC Systems"</a> <span class="cs1-format">(PDF)</span>. National Air Duct Cleaners Association. Archived from <a rel="nofollow" class="external text" href="http://www.ductandvent.com/clientuploads/NADCA-13-ACRbooklet_final.pdf">the original</a> <span class="cs1-format">(PDF)</span> on 11 February 2015<span class="reference-accessdate">. Retrieved <span class="nowrap">16 June</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=ACR%2C+The+NADCA+Standard+for+Assessment+Cleaning+Restoration+of+HVAC+Systems&rft.pub=National+Air+Duct+Cleaners+Association&rft.date=2013&rft.au=NADCA&rft_id=http%3A%2F%2Fwww.ductandvent.com%2Fclientuploads%2FNADCA-13-ACRbooklet_final.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADuct+%28flow%29" class="Z3988"></span></span> </li> <li id="cite_note-ASH180-6"><span class="mw-cite-backlink">^ <a href="#cite_ref-ASH180_6-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-ASH180_6-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFANSI/ASHRAE/ACCA2012" class="citation web cs1">ANSI/ASHRAE/ACCA (2012). <a rel="nofollow" class="external text" href="https://store.accuristech.com/ieee/standards/ashrae-180-2012?product_id=1832333">"Standard 180 Standard Practice for Inspection and Maintenance of Commercial Building HVAC Systems"</a>. American Society of Heating Ventilation and Air Conditioning Engineers<span class="reference-accessdate">. Retrieved <span class="nowrap">16 June</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Standard+180+Standard+Practice+for+Inspection+and+Maintenance+of+Commercial+Building+HVAC+Systems&rft.pub=American+Society+of+Heating+Ventilation+and+Air+Conditioning+Engineers&rft.date=2012&rft.au=ANSI%2FASHRAE%2FACCA&rft_id=https%3A%2F%2Fstore.accuristech.com%2Fieee%2Fstandards%2Fashrae-180-2012%3Fproduct_id%3D1832333&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADuct+%28flow%29" class="Z3988"></span></span> </li> <li id="cite_note-Willis-7"><span class="mw-cite-backlink">^ <a href="#cite_ref-Willis_7-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Willis_7-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWillis" class="citation web cs1">Willis, Steve. <a rel="nofollow" class="external text" href="http://www.commissioning.org/documents/Steve%20Willis%20Verifying%20Duct%20Cleanliness.pdf">"Verifying System Cleanliness: A Guide for Commissioning Providers"</a> <span class="cs1-format">(PDF)</span>. <i>www.commissioning.org</i>. American Commissioning Group (ACG)<span class="reference-accessdate">. Retrieved <span class="nowrap">16 June</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.commissioning.org&rft.atitle=Verifying+System+Cleanliness%3A+A+Guide+for+Commissioning+Providers&rft.aulast=Willis&rft.aufirst=Steve&rft_id=http%3A%2F%2Fwww.commissioning.org%2Fdocuments%2FSteve%2520Willis%2520Verifying%2520Duct%2520Cleanliness.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADuct+%28flow%29" class="Z3988"></span></span> </li> <li id="cite_note-AIIB-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-AIIB_8-0">^</a></b></span> <span class="reference-text"> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAIIB/ACRA/BSOMES/HKBCxC2004" class="citation cs2">AIIB/ACRA/BSOMES/HKBCxC (2004), <i>A Management Practice Guidance Note on Air Duct Cleaning for Hong Kong</i>, Asian Institute of Intelligent Buildings</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=A+Management+Practice+Guidance+Note+on+Air+Duct+Cleaning+for+Hong+Kong&rft.pub=Asian+Institute+of+Intelligent+Buildings&rft.date=2004&rft.au=AIIB%2FACRA%2FBSOMES%2FHKBCxC&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADuct+%28flow%29" class="Z3988"></span></span> </li> <li id="cite_note-CIBSE26-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-CIBSE26_9-0">^</a></b></span> <span class="reference-text"> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFChartered_Institute_of_Building_Service_Engineers2000" class="citation cs2">Chartered Institute of Building Service Engineers (October 2000), <i>TM 26: Hygiene Maintenance of Office Ventilation Ductwork</i></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=TM+26%3A+Hygiene+Maintenance+of+Office+Ventilation+Ductwork&rft.date=2000-10&rft.au=Chartered+Institute+of+Building+Service+Engineers&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADuct+%28flow%29" class="Z3988"></span></span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.energystar.gov/index.cfm?c=home_improvement.hm_improvement_ducts">Ductwork sealing article at Energy Star</a></span> </li> <li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.ducting-express.co.uk/category/flexible-ducting">Types of flexible ducting</a></span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Duct_(flow)&action=edit&section=27" title="Edit section: Further reading"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><i>Air Diffusion Council Flexible Duct Performance and Installation Standard</i>, 4th Ed., 2003</li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol 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href="/wiki/Dilution_(equation)" title="Dilution (equation)">Dilution</a></li> <li><a href="/wiki/Domestic_energy_consumption" title="Domestic energy consumption">Domestic energy consumption</a></li> <li><a href="/wiki/Enthalpy" title="Enthalpy">Enthalpy</a></li> <li><a href="/wiki/Fluid_dynamics" title="Fluid dynamics">Fluid dynamics</a></li> <li><a href="/wiki/Gas_compressor" class="mw-redirect" title="Gas compressor">Gas compressor</a></li> <li><a href="/wiki/Heat_pump_and_refrigeration_cycle" title="Heat pump and refrigeration cycle">Heat pump and refrigeration cycle</a></li> <li><a href="/wiki/Heat_transfer" title="Heat transfer">Heat transfer</a></li> <li><a href="/wiki/Humidity" title="Humidity">Humidity</a></li> <li><a href="/wiki/Infiltration_(HVAC)" title="Infiltration (HVAC)">Infiltration</a></li> <li><a href="/wiki/Latent_heat" title="Latent heat">Latent heat</a></li> <li><a href="/wiki/Noise_control" title="Noise control">Noise control</a></li> <li><a href="/wiki/Outgassing" title="Outgassing">Outgassing</a></li> <li><a href="/wiki/Particulates" title="Particulates">Particulates</a></li> <li><a href="/wiki/Psychrometrics" title="Psychrometrics">Psychrometrics</a></li> <li><a href="/wiki/Sensible_heat" title="Sensible heat">Sensible heat</a></li> <li><a href="/wiki/Stack_effect" title="Stack effect">Stack effect</a></li> <li><a href="/wiki/Thermal_comfort" title="Thermal comfort">Thermal comfort</a></li> <li><a href="/wiki/Thermal_destratification" title="Thermal destratification">Thermal destratification</a></li> <li><a href="/wiki/Thermal_mass" title="Thermal mass">Thermal mass</a></li> <li><a href="/wiki/Thermodynamics" title="Thermodynamics">Thermodynamics</a></li> <li><a href="/wiki/Vapour_pressure_of_water" title="Vapour pressure of water">Vapour pressure of water</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Technology</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Absorption-compression_heat_pump" title="Absorption-compression heat pump">Absorption-compression heat pump</a></li> <li><a href="/wiki/Absorption_refrigerator" title="Absorption refrigerator">Absorption refrigerator</a></li> <li><a href="/wiki/Air_barrier" title="Air barrier">Air barrier</a></li> <li><a href="/wiki/Air_conditioning" title="Air conditioning">Air conditioning</a></li> <li><a href="/wiki/Antifreeze" title="Antifreeze">Antifreeze</a></li> <li><a href="/wiki/Automobile_air_conditioning" class="mw-redirect" title="Automobile air conditioning">Automobile air conditioning</a></li> <li><a href="/wiki/Autonomous_building" title="Autonomous building">Autonomous building</a></li> <li><a href="/wiki/Building_insulation_material" title="Building insulation material">Building insulation materials</a></li> <li><a href="/wiki/Central_heating" title="Central heating">Central heating</a></li> <li><a href="/wiki/Central_solar_heating" title="Central solar heating">Central solar heating</a></li> <li><a href="/wiki/Chilled_beam" title="Chilled beam">Chilled beam</a></li> <li><a href="/wiki/Chilled_water" title="Chilled water">Chilled water</a></li> <li><a href="/wiki/Constant_air_volume" title="Constant air volume">Constant air volume</a> (CAV)</li> <li><a href="/wiki/Coolant" title="Coolant">Coolant</a></li> <li><a href="/wiki/Cross_ventilation" title="Cross ventilation">Cross ventilation</a></li> <li><a href="/wiki/Dedicated_outdoor_air_system" title="Dedicated outdoor air system">Dedicated outdoor air system</a> (DOAS)</li> <li><a href="/wiki/Deep_water_source_cooling" title="Deep water source cooling">Deep water source cooling</a></li> <li><a href="/wiki/Demand_controlled_ventilation" title="Demand controlled ventilation">Demand controlled ventilation</a> (DCV)</li> <li><a href="/wiki/Displacement_ventilation" title="Displacement ventilation">Displacement ventilation</a></li> <li><a href="/wiki/District_cooling" title="District cooling">District cooling</a></li> <li><a href="/wiki/District_heating" title="District heating">District heating</a></li> <li><a href="/wiki/Electric_heating" title="Electric heating">Electric heating</a></li> <li><a href="/wiki/Energy_recovery_ventilation" class="mw-redirect" title="Energy recovery ventilation">Energy recovery ventilation</a> (ERV)</li> <li><a href="/wiki/Firestop" title="Firestop">Firestop</a></li> <li><a href="/wiki/Forced-air" title="Forced-air">Forced-air</a></li> <li><a href="/wiki/Forced-air_gas" title="Forced-air gas">Forced-air gas</a></li> <li><a href="/wiki/Free_cooling" title="Free cooling">Free cooling</a></li> <li><a href="/wiki/Heat_recovery_ventilation" title="Heat recovery ventilation">Heat recovery ventilation</a> (HRV)</li> <li><a href="/wiki/Hybrid_heat" title="Hybrid heat">Hybrid heat</a></li> <li><a href="/wiki/Hydronics" title="Hydronics">Hydronics</a></li> <li><a href="/wiki/Ice_storage_air_conditioning" title="Ice storage air conditioning">Ice storage air conditioning</a></li> <li><a href="/wiki/Kitchen_ventilation" title="Kitchen ventilation">Kitchen ventilation</a></li> <li><a href="/wiki/Mixed-mode_ventilation" title="Mixed-mode ventilation">Mixed-mode ventilation</a></li> <li><a href="/wiki/Microgeneration" title="Microgeneration">Microgeneration</a></li> <li><a href="/wiki/Passive_cooling" title="Passive cooling">Passive cooling</a></li> <li><a href="/wiki/Passive_daytime_radiative_cooling" title="Passive daytime radiative cooling">Passive daytime radiative cooling</a></li> <li><a href="/wiki/Passive_house" title="Passive house">Passive house</a></li> <li><a href="/wiki/Passive_ventilation" title="Passive ventilation">Passive ventilation</a></li> <li><a href="/wiki/Radiant_heating_and_cooling" title="Radiant heating and cooling">Radiant heating and cooling</a></li> <li><a href="/wiki/Radiant_cooling" class="mw-redirect" title="Radiant cooling">Radiant cooling</a></li> <li><a href="/wiki/Radiant_heating" class="mw-redirect" title="Radiant heating">Radiant heating</a></li> <li><a href="/wiki/Radon_mitigation" title="Radon mitigation">Radon mitigation</a></li> <li><a href="/wiki/Refrigeration" title="Refrigeration">Refrigeration</a></li> <li><a href="/wiki/Renewable_heat" title="Renewable heat">Renewable heat</a></li> <li><a href="/wiki/Room_air_distribution" title="Room air distribution">Room air distribution</a></li> <li><a href="/wiki/Solar_air_heat" title="Solar air heat">Solar air heat</a></li> <li><a href="/wiki/Solar_combisystem" title="Solar combisystem">Solar combisystem</a></li> <li><a href="/wiki/Solar_cooling" class="mw-redirect" title="Solar cooling">Solar cooling</a></li> <li><a href="/wiki/Solar_heating" class="mw-redirect" title="Solar heating">Solar heating</a></li> <li><a href="/wiki/Thermal_insulation" title="Thermal insulation">Thermal insulation</a></li> <li><a href="/wiki/Thermosiphon" title="Thermosiphon">Thermosiphon</a></li> <li><a href="/wiki/Underfloor_air_distribution" title="Underfloor air distribution">Underfloor air distribution</a></li> <li><a href="/wiki/Underfloor_heating" title="Underfloor heating">Underfloor heating</a></li> <li><a href="/wiki/Vapor_barrier" title="Vapor barrier">Vapor barrier</a></li> <li><a href="/wiki/Vapor-compression_refrigeration" title="Vapor-compression refrigeration">Vapor-compression refrigeration</a> (VCRS)</li> <li><a href="/wiki/Variable_air_volume" title="Variable air volume">Variable air volume</a> (VAV)</li> <li><a href="/wiki/Variable_refrigerant_flow" title="Variable refrigerant flow">Variable refrigerant flow</a> (VRF)</li> <li><a href="/wiki/Ventilation_(architecture)" title="Ventilation (architecture)">Ventilation</a></li> <li><a href="/wiki/Water_heat_recycling" title="Water heat recycling">Water heat recycling</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Components</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Air_conditioner_inverter" class="mw-redirect" title="Air conditioner inverter">Air conditioner inverter</a></li> <li><a href="/wiki/Air_door" title="Air door">Air door</a></li> <li><a href="/wiki/Air_filter" title="Air filter">Air filter</a></li> <li><a href="/wiki/Air_handler" title="Air handler">Air handler</a></li> <li><a href="/wiki/Air_ioniser" title="Air ioniser">Air ionizer</a></li> <li><a href="/wiki/Air-mixing_plenum" title="Air-mixing plenum">Air-mixing plenum</a></li> <li><a href="/wiki/Air_purifier" title="Air purifier">Air purifier</a></li> <li><a href="/wiki/Air_source_heat_pump" title="Air source heat pump">Air source heat pump</a></li> <li><a href="/wiki/Attic_fan" title="Attic fan">Attic fan</a></li> <li><a href="/wiki/Automatic_balancing_valve" title="Automatic balancing valve">Automatic balancing valve</a></li> <li><a href="/wiki/Back_boiler" title="Back boiler">Back boiler</a></li> <li><a href="/wiki/Barrier_pipe" title="Barrier pipe">Barrier pipe</a></li> <li><a href="/wiki/Blast_damper" title="Blast damper">Blast damper</a></li> <li><a href="/wiki/Boiler" title="Boiler">Boiler</a></li> <li><a href="/wiki/Centrifugal_fan" title="Centrifugal fan">Centrifugal fan</a></li> <li><a href="/wiki/Ceramic_heater" title="Ceramic heater">Ceramic heater</a></li> <li><a href="/wiki/Chiller" title="Chiller">Chiller</a></li> <li><a href="/wiki/Condensate_pump" title="Condensate pump">Condensate pump</a></li> <li><a href="/wiki/Condenser_(heat_transfer)" title="Condenser (heat transfer)">Condenser</a></li> <li><a href="/wiki/Condensing_boiler" title="Condensing boiler">Condensing boiler</a></li> <li><a href="/wiki/Convection_heater" title="Convection heater">Convection heater</a></li> <li><a href="/wiki/Compressor" title="Compressor">Compressor</a></li> <li><a href="/wiki/Cooling_tower" title="Cooling tower">Cooling tower</a></li> <li><a href="/wiki/Damper_(flow)" title="Damper (flow)">Damper</a></li> <li><a href="/wiki/Dehumidifier" title="Dehumidifier">Dehumidifier</a></li> <li><a class="mw-selflink selflink">Duct</a></li> <li><a href="/wiki/Economizer" title="Economizer">Economizer</a></li> <li><a href="/wiki/Electrostatic_precipitator" title="Electrostatic precipitator">Electrostatic precipitator</a></li> <li><a href="/wiki/Evaporative_cooler" title="Evaporative cooler">Evaporative cooler</a></li> <li><a href="/wiki/Evaporator" title="Evaporator">Evaporator</a></li> <li><a href="/wiki/Exhaust_hood" class="mw-redirect" title="Exhaust hood">Exhaust hood</a></li> <li><a href="/wiki/Expansion_tank" title="Expansion tank">Expansion tank</a></li> <li><a href="/wiki/Fan_(machine)" title="Fan (machine)">Fan</a></li> <li><a href="/wiki/Fan_coil_unit" title="Fan coil unit">Fan coil unit</a></li> <li><a href="/wiki/Fan_filter_unit" title="Fan filter unit">Fan filter unit</a></li> <li><a href="/wiki/Fan_heater" title="Fan heater">Fan heater</a></li> <li><a href="/wiki/Fire_damper" title="Fire damper">Fire damper</a></li> <li><a href="/wiki/Fireplace" title="Fireplace">Fireplace</a></li> <li><a href="/wiki/Fireplace_insert" title="Fireplace insert">Fireplace insert</a></li> <li><a href="/wiki/Freeze_stat" title="Freeze stat">Freeze stat</a></li> <li><a href="/wiki/Flue" title="Flue">Flue</a></li> <li><a href="/wiki/Freon" title="Freon">Freon</a></li> <li><a href="/wiki/Fume_hood" title="Fume hood">Fume hood</a></li> <li><a href="/wiki/Furnace_(house_heating)" class="mw-redirect" title="Furnace (house heating)">Furnace</a></li> <li><a href="/wiki/Gas_compressor" class="mw-redirect" title="Gas compressor">Gas compressor</a></li> <li><a href="/wiki/Gas_heater" title="Gas heater">Gas heater</a></li> <li><a href="/wiki/Gasoline_heater" title="Gasoline heater">Gasoline heater</a></li> <li><a href="/wiki/Grease_duct" title="Grease duct">Grease duct</a></li> <li><a href="/wiki/Grille_(architecture)" title="Grille (architecture)">Grille</a></li> <li><a href="/wiki/Ground-coupled_heat_exchanger" title="Ground-coupled heat exchanger">Ground-coupled heat exchanger</a></li> <li><a href="/wiki/Ground_source_heat_pump" title="Ground source heat pump">Ground source heat pump</a></li> <li><a href="/wiki/Heat_exchanger" title="Heat exchanger">Heat exchanger</a></li> <li><a href="/wiki/Heat_pipe" title="Heat pipe">Heat pipe</a></li> <li><a href="/wiki/Heat_pump" title="Heat pump">Heat pump</a></li> <li><a href="/wiki/Heating_film" title="Heating film">Heating film</a></li> <li><a href="/wiki/Heating_system" title="Heating system">Heating system</a></li> <li><a href="/wiki/HEPA" title="HEPA">HEPA</a></li> <li><a href="/wiki/High_efficiency_glandless_circulating_pump" title="High efficiency glandless circulating pump">High efficiency glandless circulating pump</a></li> <li><a href="/wiki/High-pressure_cut-off_switch" class="mw-redirect" title="High-pressure cut-off switch">High-pressure cut-off switch</a></li> <li><a href="/wiki/Humidifier" title="Humidifier">Humidifier</a></li> <li><a href="/wiki/Infrared_heater" title="Infrared heater">Infrared heater</a></li> <li><a href="/wiki/Inverter_compressor" title="Inverter compressor">Inverter compressor</a></li> <li><a href="/wiki/Kerosene_heater" title="Kerosene heater">Kerosene heater</a></li> <li><a href="/wiki/Louver" title="Louver">Louver</a></li> <li><a href="/wiki/Mechanical_room" title="Mechanical room">Mechanical room</a></li> <li><a href="/wiki/Oil_heater" title="Oil heater">Oil heater</a></li> <li><a href="/wiki/Packaged_terminal_air_conditioner" title="Packaged terminal air conditioner">Packaged terminal air conditioner</a></li> <li><a href="/wiki/Plenum_space" title="Plenum space">Plenum space</a></li> <li><a href="/wiki/Pressurisation_ductwork" title="Pressurisation ductwork">Pressurisation ductwork</a></li> <li><a href="/wiki/Process_duct_work" title="Process duct work">Process duct work</a></li> <li><a href="/wiki/Radiator_(heating)" title="Radiator (heating)">Radiator</a></li> <li><a href="/wiki/Radiator_reflector" title="Radiator reflector">Radiator reflector</a></li> <li><a href="/wiki/Recuperator" title="Recuperator">Recuperator</a></li> <li><a href="/wiki/Refrigerant" title="Refrigerant">Refrigerant</a></li> <li><a href="/wiki/Register_(air_and_heating)" title="Register (air and heating)">Register</a></li> <li><a href="/wiki/Reversing_valve" title="Reversing valve">Reversing valve</a></li> <li><a href="/wiki/Run-around_coil" title="Run-around coil">Run-around coil</a></li> <li><a href="/wiki/Sail_switch" title="Sail switch">Sail switch</a></li> <li><a href="/wiki/Scroll_compressor" title="Scroll compressor">Scroll compressor</a></li> <li><a href="/wiki/Solar_chimney" title="Solar chimney">Solar chimney</a></li> <li><a href="/wiki/Solar-assisted_heat_pump" title="Solar-assisted heat pump">Solar-assisted heat pump</a></li> <li><a href="/wiki/Space_heater" title="Space heater">Space heater</a></li> <li><a href="/wiki/Smoke_canopy" title="Smoke canopy">Smoke canopy</a></li> <li><a href="/wiki/Smoke_damper" title="Smoke damper">Smoke damper</a></li> <li><a href="/wiki/Smoke_exhaust_ductwork" title="Smoke exhaust ductwork">Smoke exhaust ductwork</a></li> <li><a href="/wiki/Thermal_expansion_valve" title="Thermal expansion valve">Thermal expansion valve</a></li> <li><a href="/wiki/Thermal_wheel" title="Thermal wheel">Thermal wheel</a></li> <li><a href="/wiki/Thermostatic_radiator_valve" title="Thermostatic radiator valve">Thermostatic radiator valve</a></li> <li><a href="/wiki/Trickle_vent" title="Trickle vent">Trickle vent</a></li> <li><a href="/wiki/Trombe_wall" title="Trombe wall">Trombe wall</a></li> <li><a href="/wiki/TurboSwing" title="TurboSwing">TurboSwing</a></li> <li><a href="/wiki/Turning_vanes_(HVAC)" title="Turning vanes (HVAC)">Turning vanes</a></li> <li><a href="/wiki/Ultra-low_particulate_air" title="Ultra-low particulate air">Ultra-low particulate air</a> (ULPA)</li> <li><a href="/wiki/Whole-house_fan" title="Whole-house fan">Whole-house fan</a></li> <li><a href="/wiki/Windcatcher" title="Windcatcher">Windcatcher</a></li> <li><a href="/wiki/Wood-burning_stove" title="Wood-burning stove">Wood-burning stove</a></li> <li><a href="/wiki/Zone_valve" title="Zone valve">Zone valve</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Measurement<br />and control</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Air_flow_meter" title="Air flow meter">Air flow meter</a></li> <li><a href="/wiki/Aquastat" title="Aquastat">Aquastat</a></li> <li><a href="/wiki/BACnet" title="BACnet">BACnet</a></li> <li><a href="/wiki/Blower_door" title="Blower door">Blower door</a></li> <li><a href="/wiki/Building_automation" title="Building automation">Building automation</a></li> <li><a href="/wiki/Carbon_dioxide_sensor" title="Carbon dioxide sensor">Carbon dioxide sensor</a></li> <li><a href="/wiki/Clean_air_delivery_rate" title="Clean air delivery rate">Clean air delivery rate</a> (CADR)</li> <li><a href="/wiki/Control_valve" title="Control valve">Control valve</a></li> <li><a href="/wiki/Gas_detector" title="Gas detector">Gas detector</a></li> <li><a href="/wiki/Home_energy_monitor" title="Home energy monitor">Home energy monitor</a></li> <li><a href="/wiki/Humidistat" title="Humidistat">Humidistat</a></li> <li><a href="/wiki/HVAC_control_system" title="HVAC control system">HVAC control system</a></li> <li><a href="/wiki/Infrared_thermometer" title="Infrared thermometer">Infrared thermometer</a></li> <li><a href="/wiki/Intelligent_buildings" class="mw-redirect" title="Intelligent buildings">Intelligent buildings</a></li> <li><a href="/wiki/LonWorks" title="LonWorks">LonWorks</a></li> <li><a href="/wiki/Minimum_efficiency_reporting_value" title="Minimum efficiency reporting value">Minimum efficiency reporting value</a> (MERV)</li> <li><a href="/wiki/Normal_temperature_and_pressure" class="mw-redirect" title="Normal temperature and pressure">Normal temperature and pressure</a> (NTP)</li> <li><a href="/wiki/OpenTherm" title="OpenTherm">OpenTherm</a></li> <li><a href="/wiki/Programmable_communicating_thermostat" title="Programmable communicating thermostat">Programmable communicating thermostat</a></li> <li><a href="/wiki/Programmable_thermostat" title="Programmable thermostat">Programmable thermostat</a></li> <li><a href="/wiki/Psychrometrics" title="Psychrometrics">Psychrometrics</a></li> <li><a href="/wiki/Room_temperature" title="Room temperature">Room temperature</a></li> <li><a href="/wiki/Smart_thermostat" title="Smart thermostat">Smart thermostat</a></li> <li><a href="/wiki/Standard_temperature_and_pressure" title="Standard temperature and pressure">Standard temperature and pressure</a> (STP)</li> <li><a href="/wiki/Thermographic_camera" class="mw-redirect" title="Thermographic camera">Thermographic camera</a></li> <li><a href="/wiki/Thermostat" title="Thermostat">Thermostat</a></li> <li><a href="/wiki/Thermostatic_radiator_valve" title="Thermostatic radiator valve">Thermostatic radiator valve</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Professions,<br />trades,<br />and services</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Architectural_acoustics" title="Architectural acoustics">Architectural acoustics</a></li> <li><a href="/wiki/Architectural_engineering" title="Architectural engineering">Architectural engineering</a></li> <li><a href="/wiki/Architectural_technologist" title="Architectural technologist">Architectural technologist</a></li> <li><a href="/wiki/Building_services_engineering" title="Building services engineering">Building services engineering</a></li> <li><a href="/wiki/Building_information_modeling" title="Building information modeling">Building information modeling</a> (BIM)</li> <li><a href="/wiki/Deep_energy_retrofit" title="Deep energy retrofit">Deep energy retrofit</a></li> <li><a href="/wiki/Duct_cleaning" class="mw-redirect" title="Duct cleaning">Duct cleaning</a></li> <li><a href="/wiki/Duct_leakage_testing" title="Duct leakage testing">Duct leakage testing</a></li> <li><a href="/wiki/Environmental_engineering" title="Environmental engineering">Environmental engineering</a></li> <li><a href="/wiki/Hydronic_balancing" title="Hydronic balancing">Hydronic balancing</a></li> <li><a href="/wiki/Kitchen_exhaust_cleaning" title="Kitchen exhaust cleaning">Kitchen exhaust cleaning</a></li> <li><a href="/wiki/Mechanical_engineering" title="Mechanical engineering">Mechanical engineering</a></li> <li><a href="/wiki/Mechanical,_electrical,_and_plumbing" title="Mechanical, electrical, and plumbing">Mechanical, electrical, and plumbing</a></li> <li><a href="/wiki/Mold_growth,_assessment,_and_remediation" class="mw-redirect" title="Mold growth, assessment, and remediation">Mold growth, assessment, and remediation</a></li> <li><a href="/wiki/Refrigerant_reclamation" title="Refrigerant reclamation">Refrigerant reclamation</a></li> <li><a href="/wiki/Testing,_adjusting,_balancing" title="Testing, adjusting, balancing">Testing, adjusting, balancing</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Industry <br />organizations</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Air_Conditioning,_Heating_and_Refrigeration_Institute" title="Air Conditioning, Heating and Refrigeration Institute">AHRI</a></li> <li><a href="/wiki/Air_Movement_and_Control_Association" title="Air Movement and Control Association">AMCA</a></li> <li><a href="/wiki/ASHRAE" title="ASHRAE">ASHRAE</a></li> <li><a href="/wiki/ASTM_International" title="ASTM International">ASTM International</a></li> <li><a href="/wiki/Building_Research_Establishment" title="Building Research Establishment">BRE</a></li> <li><a href="/wiki/BSRIA" title="BSRIA">BSRIA</a></li> <li><a href="/wiki/Chartered_Institution_of_Building_Services_Engineers" title="Chartered Institution of Building Services Engineers">CIBSE</a></li> <li><a href="/wiki/Institute_of_Refrigeration" title="Institute of Refrigeration">Institute of Refrigeration</a></li> <li><a href="/wiki/International_Institute_of_Refrigeration" title="International Institute of Refrigeration">IIR</a></li> <li><a href="/wiki/Leadership_in_Energy_and_Environmental_Design" class="mw-redirect" title="Leadership in Energy and Environmental Design">LEED</a></li> <li><a href="/wiki/Sheet_Metal_and_Air_Conditioning_Contractors%27_National_Association" title="Sheet Metal and Air Conditioning Contractors' National Association">SMACNA</a></li> <li><a href="/wiki/Uniform_Mechanical_Code" title="Uniform Mechanical Code">UMC</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Health and safety</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Indoor_air_quality" title="Indoor air quality">Indoor air quality</a> (IAQ)</li> <li><a href="/wiki/Passive_smoking" title="Passive smoking">Passive smoking</a></li> <li><a href="/wiki/Sick_building_syndrome" title="Sick building syndrome">Sick building syndrome</a> (SBS)</li> <li><a href="/wiki/Volatile_organic_compound" title="Volatile organic compound">Volatile organic compound</a> (VOC)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">See also</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/ASHRAE_Handbook" title="ASHRAE Handbook">ASHRAE Handbook</a></li> <li><a href="/wiki/Building_science" title="Building science">Building science</a></li> <li><a href="/wiki/Fireproofing" title="Fireproofing">Fireproofing</a></li> <li><a href="/wiki/Glossary_of_HVAC_terms" title="Glossary of HVAC terms">Glossary of HVAC terms</a></li> <li><a href="/wiki/Warm_Spaces" title="Warm Spaces">Warm Spaces</a></li> <li><a href="/wiki/World_Refrigeration_Day" title="World Refrigeration Day">World Refrigeration Day</a></li> <li><a href="/wiki/Template:Home_automation" title="Template:Home automation">Template:Home automation</a></li> <li><a href="/wiki/Template:Solar_energy" title="Template:Solar energy">Template:Solar energy</a></li></ul> </div></td></tr></tbody></table></div>    </div><noscript><img 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