{"id":92,"date":"2021-01-27T14:27:46","date_gmt":"2021-01-27T19:27:46","guid":{"rendered":"https:\/\/opentextbc.ca\/basichvac\/chapter\/dampers\/"},"modified":"2023-03-02T11:43:52","modified_gmt":"2023-03-02T16:43:52","slug":"dampers","status":"publish","type":"chapter","link":"https:\/\/opentextbc.ca\/basichvac\/chapter\/dampers\/","title":{"raw":"Dampers","rendered":"Dampers"},"content":{"raw":"Click play on the following audio player to listen along as you read this section.\r\n\r\nhttps:\/\/media.bccampus.ca\/id\/0_ck8qsva8?width=608&amp;height=80&amp;playerId=23449753\r\n\r\nDampers are devices installed in the ductwork of air systems to regulate the flow of air. They can be controlled manually or remotely and can be used to ensure a certain percentage of the return airflow is mixed with incoming air from outside. This helps ensure that healthy levels of fresh air are added to the recirculating air flow system.\r\n\r\nMost sets of dampers consist of a U-channel frame with several connected sheet-metal blades which are driven by a small motor. The edges of the sheet-metal blades will have rubber seals to help provide a tighter barrier to air when in the closed position.\r\n\r\n[caption id=\"attachment_91\" align=\"aligncenter\" width=\"456\"]<img class=\"wp-image-91 size-full\" src=\"https:\/\/opentextbc.ca\/accessibilitytoolkit\/wp-content\/uploads\/sites\/336\/2021\/02\/Dampers.png\" alt=\"Parallel blade dampers have all of blades angled the same way. Opposing blade dampers have blades angled alternating ways.\" width=\"456\" height=\"326\" \/> Parallel and opposing blade dampers.[\/caption]\r\n\r\nDampers are divided into two categories depending upon how their blades rotate relative to each other. <strong>[pb_glossary id=\"164\"]Opposed blade dampers[\/pb_glossary]<\/strong> are constructed so that adjacent blades rotate in opposite directions, while [pb_glossary id=\"165\"]<strong>parallel blade <\/strong>dampers[\/pb_glossary] have all blades rotating in the same direction, similar to Venetian blinds.\r\n\r\nMotor driven dampers that are part of larger commercial or industrial HVAC systems will have power-fail positions that they will revert to in the event of a loss of voltage.\r\n\r\nMotor driven dampers are controlled by <strong>[pb_glossary id=\"223\"]actuators[\/pb_glossary]<\/strong>, which contain a spiral spring inside their housing that tightens clockwise as the motor is driven. This spring provides the stored energy to return the sheet-metal blades back to their original position should electrical power be disconnected from the actuator. When installing actuators care must be taken to ensure that in the event of a power failure the spring in the actuator returns the damper blades to the desired default power-fail position.\r\n\r\nOutside and exhaust dampers will generally revert to a normally-closed (NC) position, while return air dampers will revert to their normally-open (NO) position to ensure that any supply fans are not deprived of fresh air.","rendered":"<p>Click play on the following audio player to listen along as you read this section.<\/p>\n<p><iframe loading=\"lazy\" id=\"kaltura_player\" title=\"3.27 Dampers\" src=\"https:\/\/api.ca.kaltura.com\/p\/148\/sp\/14800\/embedIframeJs\/uiconf_id\/23449753\/partner_id\/148?iframeembed=true&#38;playerId=kaltura_player&#38;entry_id=0_ck8qsva8&#38;flashvars[leadWithHTML5]=true&#38;flashvars[streamerType]=auto&#38;flashvars[localizationCode]=en&#38;flashvars[sideBarContainer.plugin]=true&#38;flashvars[sideBarContainer.position]=left&#38;flashvars[sideBarContainer.clickToClose]=true&#38;flashvars[chapters.plugin]=true&#38;flashvars[chapters.layout]=vertical&#38;flashvars[chapters.thumbnailRotator]=false&#38;flashvars[streamSelector.plugin]=true&#38;flashvars[EmbedPlayer.SpinnerTarget]=videoHolder&#38;flashvars[dualScreen.plugin]=true&#38;flashvars[Kaltura.addCrossoriginToIframe]=true&#38;wid=0_4ewm3psc\" width=\"608\" height=\"80\" allowfullscreen=\"allowfullscreen\" sandbox=\"allow-downloads allow-forms allow-same-origin allow-scripts allow-top-navigation allow-pointer-lock allow-popups allow-modals allow-orientation-lock allow-popups-to-escape-sandbox allow-presentation allow-top-navigation-by-user-activation\" frameborder=\"0\"><\/iframe><\/p>\n<p>Dampers are devices installed in the ductwork of air systems to regulate the flow of air. They can be controlled manually or remotely and can be used to ensure a certain percentage of the return airflow is mixed with incoming air from outside. This helps ensure that healthy levels of fresh air are added to the recirculating air flow system.<\/p>\n<p>Most sets of dampers consist of a U-channel frame with several connected sheet-metal blades which are driven by a small motor. The edges of the sheet-metal blades will have rubber seals to help provide a tighter barrier to air when in the closed position.<\/p>\n<figure id=\"attachment_91\" aria-describedby=\"caption-attachment-91\" style=\"width: 456px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-91 size-full\" src=\"https:\/\/opentextbc.ca\/accessibilitytoolkit\/wp-content\/uploads\/sites\/336\/2021\/02\/Dampers.png\" alt=\"Parallel blade dampers have all of blades angled the same way. Opposing blade dampers have blades angled alternating ways.\" width=\"456\" height=\"326\" srcset=\"https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/02\/Dampers.png 456w, https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/02\/Dampers-300x214.png 300w, https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/02\/Dampers-65x46.png 65w, https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/02\/Dampers-225x161.png 225w, https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/02\/Dampers-350x250.png 350w\" sizes=\"auto, (max-width: 456px) 100vw, 456px\" \/><figcaption id=\"caption-attachment-91\" class=\"wp-caption-text\">Parallel and opposing blade dampers.<\/figcaption><\/figure>\n<p>Dampers are divided into two categories depending upon how their blades rotate relative to each other. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_92_164\">Opposed blade dampers<\/a><\/strong> are constructed so that adjacent blades rotate in opposite directions, while <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_92_165\"><strong>parallel blade <\/strong>dampers<\/a> have all blades rotating in the same direction, similar to Venetian blinds.<\/p>\n<p>Motor driven dampers that are part of larger commercial or industrial HVAC systems will have power-fail positions that they will revert to in the event of a loss of voltage.<\/p>\n<p>Motor driven dampers are controlled by <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_92_223\">actuators<\/a><\/strong>, which contain a spiral spring inside their housing that tightens clockwise as the motor is driven. This spring provides the stored energy to return the sheet-metal blades back to their original position should electrical power be disconnected from the actuator. When installing actuators care must be taken to ensure that in the event of a power failure the spring in the actuator returns the damper blades to the desired default power-fail position.<\/p>\n<p>Outside and exhaust dampers will generally revert to a normally-closed (NC) position, while return air dampers will revert to their normally-open (NO) position to ensure that any supply fans are not deprived of fresh air.<\/p>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_92_164\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_92_164\"><div tabindex=\"-1\"><p>Blades that alternate their direction of rotation.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_92_165\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_92_165\"><div tabindex=\"-1\"><p>Blades that all rotate in the same direction.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_92_223\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_92_223\"><div tabindex=\"-1\"><p>A electromechanical device that controls damper blade position. It has a spring-loaded coil to return dampers to a fail-safe position in case of loss of power.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":90,"menu_order":6,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-92","chapter","type-chapter","status-publish","hentry"],"part":78,"_links":{"self":[{"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/chapters\/92","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/wp\/v2\/users\/90"}],"version-history":[{"count":3,"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/chapters\/92\/revisions"}],"predecessor-version":[{"id":353,"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/chapters\/92\/revisions\/353"}],"part":[{"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/parts\/78"}],"metadata":[{"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/chapters\/92\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/wp\/v2\/media?parent=92"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/chapter-type?post=92"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/wp\/v2\/contributor?post=92"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/wp\/v2\/license?post=92"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}