{"id":89,"date":"2021-02-13T16:24:21","date_gmt":"2021-02-13T21:24:21","guid":{"rendered":"https:\/\/opentextbc.ca\/basichvac\/chapter\/fan-substitutions\/"},"modified":"2023-03-02T11:43:21","modified_gmt":"2023-03-02T16:43:21","slug":"fan-substitutions","status":"publish","type":"chapter","link":"https:\/\/opentextbc.ca\/basichvac\/chapter\/fan-substitutions\/","title":{"raw":"Fan Substitutions","rendered":"Fan Substitutions"},"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_9jhsb4ph?width=608&amp;height=80&amp;playerId=23449753\r\n\r\nThere are three important considerations to keep in mind when changing the motors of HVAC fans, if a change in [pb_glossary id=\"162\"]<strong>speed<\/strong>[\/pb_glossary] or <strong>[pb_glossary id=\"163\"]horsepower[\/pb_glossary]<\/strong> is also involved.\r\n\r\nThe first is that airflow varies directly with fan speed, so doubling the speed of the fan will double the airflow.\r\n<p style=\"text-align: center;\">[latex]\\text{Fan Speed}=\\text{Air Flow}[\/latex]<\/p>\r\nThe second is that static pressure varies with the square of the fan speed, so that doubling the fan speed will quadruple the static pressure in the ductwork.\r\n<p style=\"text-align: center;\">[latex]\\text{Fan Speed}={\\text{Static Pressure}}^{2}[\/latex]<\/p>\r\nThe third consideration is that electrical power consumed by the motor varies with the cube of the fan speed, so that it requires a motor with eight-times the horsepower rating of the previous motor to double the fan speed.\r\n<p style=\"text-align: center;\">[latex]\\text{Fan Speed}={\\text{Power Consumed}}^{3}[\/latex]<\/p>\r\nThis will result in a very significant change in the demand of the electrical draw of the motor. Be sure not to exceed the current, voltage, or horsepower ratings of any electrical circuits, or overcurrent devices.","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=\"3.26 Fan Substitutions\" 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_9jhsb4ph&#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_8gs0mesx\" 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>There are three important considerations to keep in mind when changing the motors of HVAC fans, if a change in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_89_162\"><strong>speed<\/strong><\/a> or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_89_163\">horsepower<\/a><\/strong> is also involved.<\/p>\n<p>The first is that airflow varies directly with fan speed, so doubling the speed of the fan will double the airflow.<\/p>\n<p style=\"text-align: center;\">[latex]\\text{Fan Speed}=\\text{Air Flow}[\/latex]<\/p>\n<p>The second is that static pressure varies with the square of the fan speed, so that doubling the fan speed will quadruple the static pressure in the ductwork.<\/p>\n<p style=\"text-align: center;\">[latex]\\text{Fan Speed}={\\text{Static Pressure}}^{2}[\/latex]<\/p>\n<p>The third consideration is that electrical power consumed by the motor varies with the cube of the fan speed, so that it requires a motor with eight-times the horsepower rating of the previous motor to double the fan speed.<\/p>\n<p style=\"text-align: center;\">[latex]\\text{Fan Speed}={\\text{Power Consumed}}^{3}[\/latex]<\/p>\n<p>This will result in a very significant change in the demand of the electrical draw of the motor. Be sure not to exceed the current, voltage, or horsepower ratings of any electrical circuits, or overcurrent devices.<\/p>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_89_162\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_89_162\"><div tabindex=\"-1\"><p>The speed or RPM of a fan determines how fast it rotates.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_89_163\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_89_163\"><div tabindex=\"-1\"><p>How much electric power is consumed by the motor. 1 horsepower is the equivalent of 746 watts.<\/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":5,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-89","chapter","type-chapter","status-publish","hentry"],"part":78,"_links":{"self":[{"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/chapters\/89","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\/89\/revisions"}],"predecessor-version":[{"id":352,"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/chapters\/89\/revisions\/352"}],"part":[{"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/parts\/78"}],"metadata":[{"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/chapters\/89\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/wp\/v2\/media?parent=89"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/chapter-type?post=89"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/wp\/v2\/contributor?post=89"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/wp\/v2\/license?post=89"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}