{"id":43,"date":"2021-02-11T18:16:57","date_gmt":"2021-02-11T23:16:57","guid":{"rendered":"https:\/\/opentextbc.ca\/basichvac\/chapter\/line-voltage-thermostats\/"},"modified":"2023-03-02T11:32:47","modified_gmt":"2023-03-02T16:32:47","slug":"line-voltage-thermostats","status":"publish","type":"chapter","link":"https:\/\/opentextbc.ca\/basichvac\/chapter\/line-voltage-thermostats\/","title":{"raw":"Line Voltage Thermostats","rendered":"Line Voltage Thermostats"},"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_t2h3cut2?width=608&amp;height=80&amp;playerId=23449753\r\n\r\nLine-voltage thermostats are available as either single-pole single throw (SPST) or double-pole single throw (DPST) switch types and are popular for use with baseboard heaters. They are relatively inexpensive and act as on\/off switches to conduct full power to the heater load.\r\n\r\n[caption id=\"attachment_42\" align=\"aligncenter\" width=\"377\"]<img class=\"wp-image-41 size-full\" src=\"https:\/\/opentextbc.ca\/accessibilitytoolkit\/wp-content\/uploads\/sites\/336\/2021\/01\/Thermostat-contacts.png\" alt=\"Diagram of a A 120 V SPST thermostat and a 240 V DPST thermostat.\" width=\"377\" height=\"217\" \/> Line-voltage thermostat contacts.[\/caption]\r\n\r\nUsed most commonly with multiple baseboard heaters, line-voltage thermostats must be installed in each room or heated area to allow precise control of heat.\r\n\r\nFor example, it is common to install a baseboard heater under the window in every room with an exterior wall and have one thermostat near the entrance to that room, either above or beside the light switch, to control that individual heater.\u00a0 This ensures that the whole room will be heated before the thermostat clicks off, but that the unoccupied room next door does not heat up.\r\n\r\nSince heating loads are energized at 240V for increased efficiency, thermostats controlling them are not allowed to have a marked \"OFF\" position unless they open all ungrounded conductors. This means that only a double-pole, single-throw (DPST) thermostat will have an \"OFF\" position, while a single-pole, single-throw (SPST) thermostat will instead be marked \"LOW\" or \"MIN.\"\r\n\r\nRegardless of the type of thermostat used, NEVER use a thermostat as a disconnecting means before working on a baseboard heater. Disconnect the power at the source and verify it is dead before working on any voltage source.\r\n\r\nLine-voltage thermostats must be <strong>[pb_glossary id=\"183\"]rated[\/pb_glossary]<\/strong> for the voltage, current and power ratings of the loads they will be controlling. For example a thermostat rated at 240 volts and 2880 watts must only be used to control maximum 12 amps of load current.\r\n<p style=\"text-align: center;\">[latex]12\\text{ A}=\\dfrac{2880 \\text{W}}{240\\text{ V}}[\/latex]<\/p>\r\n\r\n\r\n[caption id=\"attachment_42\" align=\"aligncenter\" width=\"489\"]<img class=\"wp-image-42\" src=\"https:\/\/opentextbc.ca\/accessibilitytoolkit\/wp-content\/uploads\/sites\/336\/2021\/03\/Line-voltage-thermostat-1024x424.png\" alt=\"A thermostat that has been taken apart. It has a dial that you use to set the temperature.\" width=\"489\" height=\"202\" \/> A standard SPST line voltage thermostat[\/caption]","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=\"2.8 Line Voltage Thermostats\" 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_t2h3cut2&#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_0zz14485\" 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>Line-voltage thermostats are available as either single-pole single throw (SPST) or double-pole single throw (DPST) switch types and are popular for use with baseboard heaters. They are relatively inexpensive and act as on\/off switches to conduct full power to the heater load.<\/p>\n<figure id=\"attachment_42\" aria-describedby=\"caption-attachment-42\" style=\"width: 377px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-41 size-full\" src=\"https:\/\/opentextbc.ca\/accessibilitytoolkit\/wp-content\/uploads\/sites\/336\/2021\/01\/Thermostat-contacts.png\" alt=\"Diagram of a A 120 V SPST thermostat and a 240 V DPST thermostat.\" width=\"377\" height=\"217\" srcset=\"https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/01\/Thermostat-contacts.png 377w, https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/01\/Thermostat-contacts-300x173.png 300w, https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/01\/Thermostat-contacts-65x37.png 65w, https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/01\/Thermostat-contacts-225x130.png 225w, https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/01\/Thermostat-contacts-350x201.png 350w\" sizes=\"auto, (max-width: 377px) 100vw, 377px\" \/><figcaption id=\"caption-attachment-42\" class=\"wp-caption-text\">Line-voltage thermostat contacts.<\/figcaption><\/figure>\n<p>Used most commonly with multiple baseboard heaters, line-voltage thermostats must be installed in each room or heated area to allow precise control of heat.<\/p>\n<p>For example, it is common to install a baseboard heater under the window in every room with an exterior wall and have one thermostat near the entrance to that room, either above or beside the light switch, to control that individual heater.\u00a0 This ensures that the whole room will be heated before the thermostat clicks off, but that the unoccupied room next door does not heat up.<\/p>\n<p>Since heating loads are energized at 240V for increased efficiency, thermostats controlling them are not allowed to have a marked &#8220;OFF&#8221; position unless they open all ungrounded conductors. This means that only a double-pole, single-throw (DPST) thermostat will have an &#8220;OFF&#8221; position, while a single-pole, single-throw (SPST) thermostat will instead be marked &#8220;LOW&#8221; or &#8220;MIN.&#8221;<\/p>\n<p>Regardless of the type of thermostat used, NEVER use a thermostat as a disconnecting means before working on a baseboard heater. Disconnect the power at the source and verify it is dead before working on any voltage source.<\/p>\n<p>Line-voltage thermostats must be <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_43_183\">rated<\/a><\/strong> for the voltage, current and power ratings of the loads they will be controlling. For example a thermostat rated at 240 volts and 2880 watts must only be used to control maximum 12 amps of load current.<\/p>\n<p style=\"text-align: center;\">[latex]12\\text{ A}=\\dfrac{2880 \\text{W}}{240\\text{ V}}[\/latex]<\/p>\n<figure id=\"attachment_42\" aria-describedby=\"caption-attachment-42\" style=\"width: 489px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-42\" src=\"https:\/\/opentextbc.ca\/accessibilitytoolkit\/wp-content\/uploads\/sites\/336\/2021\/03\/Line-voltage-thermostat-1024x424.png\" alt=\"A thermostat that has been taken apart. It has a dial that you use to set the temperature.\" width=\"489\" height=\"202\" srcset=\"https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/03\/Line-voltage-thermostat-1024x424.png 1024w, https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/03\/Line-voltage-thermostat-300x124.png 300w, https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/03\/Line-voltage-thermostat-768x318.png 768w, https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/03\/Line-voltage-thermostat-1536x635.png 1536w, https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/03\/Line-voltage-thermostat-2048x847.png 2048w, https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/03\/Line-voltage-thermostat-65x27.png 65w, https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/03\/Line-voltage-thermostat-225x93.png 225w, https:\/\/opentextbc.ca\/basichvac\/wp-content\/uploads\/sites\/336\/2021\/03\/Line-voltage-thermostat-350x145.png 350w\" sizes=\"auto, (max-width: 489px) 100vw, 489px\" \/><figcaption id=\"caption-attachment-42\" class=\"wp-caption-text\">A standard SPST line voltage thermostat<\/figcaption><\/figure>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_43_183\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_43_183\"><div tabindex=\"-1\"><p>Meaning the component is designed to be safely operated within certain tolerances. EG: A 240V Rated switch could safely switch a 120V load, but not a 480V load.<\/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":2,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-43","chapter","type-chapter","status-publish","hentry"],"part":37,"_links":{"self":[{"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/chapters\/43","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\/43\/revisions"}],"predecessor-version":[{"id":334,"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/chapters\/43\/revisions\/334"}],"part":[{"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/parts\/37"}],"metadata":[{"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/chapters\/43\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/wp\/v2\/media?parent=43"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/pressbooks\/v2\/chapter-type?post=43"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/wp\/v2\/contributor?post=43"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/opentextbc.ca\/basichvac\/wp-json\/wp\/v2\/license?post=43"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}