{"id":1349,"date":"2026-04-11T06:48:27","date_gmt":"2026-04-11T05:48:27","guid":{"rendered":"https:\/\/strover.com\/?p=1349"},"modified":"2026-04-11T11:55:30","modified_gmt":"2026-04-11T10:55:30","slug":"smart-switch-upgrade-for-immersion-heater","status":"publish","type":"post","link":"https:\/\/strover.com\/?p=1349","title":{"rendered":"Smart Switch Upgrade for Immersion Heater"},"content":{"rendered":"\n<p>This is a project to convert an existing hot water immersion tank from a simple on \/ off manual switch to a configurable system with remote access. The challenge is to keep it electrically safe; a simple design; whilst on a budget.<\/p>\n\n\n\n<figure class=\"wp-block-gallery has-nested-images columns-default is-cropped wp-block-gallery-1 is-layout-flex wp-block-gallery-is-layout-flex\">\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/particulier.edf.fr\/en\/home\/contract-and-consumption\/meter\/linky-meter.html\"><img loading=\"lazy\" decoding=\"async\" width=\"640\" height=\"640\" data-id=\"1368\" src=\"https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6401.jpeg\" alt=\"\" class=\"wp-image-1368\" srcset=\"https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6401.jpeg 640w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6401-300x300.jpeg 300w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6401-150x150.jpeg 150w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6401-100x100.jpeg 100w\" sizes=\"auto, (max-width: 640px) 100vw, 640px\" \/><\/a><figcaption class=\"wp-element-caption\">Linky Smart Meter (Mains) &amp; Consumer Unit<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"480\" height=\"640\" data-id=\"1367\" src=\"https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6402.jpeg\" alt=\"\" class=\"wp-image-1367\" srcset=\"https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6402.jpeg 480w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6402-225x300.jpeg 225w\" sizes=\"auto, (max-width: 480px) 100vw, 480px\" \/><figcaption class=\"wp-element-caption\">Ballon d&#8217;eau chaude sanitaire (Immersion heater)<\/figcaption><\/figure>\n<\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Option A<\/h2>\n\n\n\n<p>Install a smart switch directly to the immersion heater.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Option B<\/h2>\n\n\n\n<p>Install a smart switch to the consumer unit feeding electricity to the immersion heater.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Option C<\/h2>\n\n\n\n<p>Save myself the bother.. and get a plumber\/electrician to do the job. Not an option for a curious DIYer &#8211; or particularly easy in France!<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Chosen Approach<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Option A requires a smart switch rated for a high current (~16 amps for a 3000W heater) and &#8216;wet contact&#8217; plus opening up the internal workings of the heater. <\/li>\n\n\n\n<li>Option B makes use of an existing <strong>relay switch<\/strong> on the water heater circuit. This is electrically safer since the switching can be triggered from the low current side of the relay. However, it meant working on a consumer unit for the first time.<\/li>\n\n\n\n<li>Option B is chosen.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Contacteur Jour\/Nuit<\/h2>\n\n\n\n<p>In France, this relay switch is called the Contacteur Jour\/Nuit. It is designed to allow hot water tanks to make use of cheaper electricity at night. <\/p>\n\n\n\n<p>It has 3 settings: I, Auto and 0. Since our electricity tariff with EDF is a basic tariff, this Jour\/Nuit facility is not installed. Fortunately, this meant the Auto setting of the relay could be re-purposed for a smart switch installation.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"480\" height=\"640\" src=\"https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6397.jpeg\" alt=\"\" class=\"wp-image-1372\" srcset=\"https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6397.jpeg 480w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6397-225x300.jpeg 225w\" sizes=\"auto, (max-width: 480px) 100vw, 480px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Circuit Breaker<\/h2>\n\n\n\n<p>The Contacteur Jour\/Nuit sit downstream of the circuit breaker for the hot water heater. This proves to be convenient later as the spare terminals are used to power the smart switch.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"480\" height=\"640\" src=\"https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6398.jpeg\" alt=\"\" class=\"wp-image-1371\" srcset=\"https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6398.jpeg 480w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6398-225x300.jpeg 225w\" sizes=\"auto, (max-width: 480px) 100vw, 480px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Purchases<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Shelly 1 Gen 3 smart switch\n<ul class=\"wp-block-list\">\n<li>This is suitable for a <strong>dry contact<\/strong> installation. Dry\u00a0contact\u00a0is defined as a switch that controls\u00a0electrical\u00a0circuits without supplying the power itself. Gen 3 can be accessed via WiFi. <\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>DIN Rail Holder for Shelly smart switch\n<ul class=\"wp-block-list\">\n<li>This is a 3D-printed device to secure the smart switch inside of the consumer unit.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>2.5mm gauge solid core electrical wire. \n<ul class=\"wp-block-list\">\n<li>This is consistent with existing electrical cabling within the consumer unit.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>2 * Wago 221 connectors<\/li>\n<\/ul>\n\n\n\n<p>Total Cost ~\u20ac30<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Wiring<\/h2>\n\n\n\n<figure class=\"wp-block-gallery has-nested-images columns-default is-cropped wp-block-gallery-2 is-layout-flex wp-block-gallery-is-layout-flex\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"1024\" data-id=\"1369\" src=\"https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6400-1024x1024.jpeg\" alt=\"\" class=\"wp-image-1369\" srcset=\"https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6400-1024x1024.jpeg 1024w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6400-300x300.jpeg 300w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6400-150x150.jpeg 150w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6400-768x768.jpeg 768w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6400-100x100.jpeg 100w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6400.jpeg 1431w\" sizes=\"auto, (max-width: 706px) 89vw, (max-width: 767px) 82vw, 740px\" \/><figcaption class=\"wp-element-caption\">Space already exists to the left of the Contacteur Jour\/Nuit<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"640\" height=\"640\" data-id=\"1370\" src=\"https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6399-1.jpeg\" alt=\"\" class=\"wp-image-1370\" srcset=\"https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6399-1.jpeg 640w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6399-1-300x300.jpeg 300w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6399-1-150x150.jpeg 150w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6399-1-100x100.jpeg 100w\" sizes=\"auto, (max-width: 640px) 100vw, 640px\" \/><figcaption class=\"wp-element-caption\">Smart switched installed<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"768\" height=\"1024\" data-id=\"1364\" src=\"https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6399-768x1024.jpeg\" alt=\"\" class=\"wp-image-1364\" srcset=\"https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6399-768x1025.jpeg 768w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6399-225x300.jpeg 225w, https:\/\/strover.com\/wp-content\/uploads\/2026\/04\/IMG_6399.jpeg 1009w\" sizes=\"auto, (max-width: 706px) 89vw, (max-width: 767px) 82vw, 740px\" \/><figcaption class=\"wp-element-caption\">Detailed view<\/figcaption><\/figure>\n<\/figure>\n\n\n\n<div class=\"wp-block-group\"><div class=\"wp-block-group__inner-container is-layout-constrained wp-block-group-is-layout-constrained\">\n<figure class=\"wp-block-table alignleft\"><table class=\"has-fixed-layout\"><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\">#<\/td><td>Shelly<\/td><td>Contacteur Jour\/Nuit<\/td><td>Circuit Breaker<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">1<\/td><td>Neutral<\/td><td>A2 (Neutral)<\/td><td>Neutral<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">2<\/td><td>Permanent Live (L)<\/td><td><\/td><td>Permanent Live<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">3<\/td><td>Input Live (I) jumper to Shelly (L)<\/td><td><\/td><td><\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">4<\/td><td>Output Live (O)<\/td><td>A1 (Live)<\/td><td><\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div><\/div>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>This is a project to convert an existing hot water immersion tank from a simple on \/ off manual switch to a configurable system with remote access. The challenge is to keep it electrically safe; a simple design; whilst on a budget. Option A Install a smart switch directly to the immersion heater. Option B &hellip; <\/p>\n<p class=\"link-more\"><a href=\"https:\/\/strover.com\/?p=1349\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Smart Switch Upgrade for Immersion Heater&#8221;<\/span><\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1349","post","type-post","status-publish","format-standard","hentry","category-uncategorised"],"_links":{"self":[{"href":"https:\/\/strover.com\/index.php?rest_route=\/wp\/v2\/posts\/1349","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/strover.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/strover.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/strover.com\/index.php?rest_route=\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/strover.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1349"}],"version-history":[{"count":16,"href":"https:\/\/strover.com\/index.php?rest_route=\/wp\/v2\/posts\/1349\/revisions"}],"predecessor-version":[{"id":1375,"href":"https:\/\/strover.com\/index.php?rest_route=\/wp\/v2\/posts\/1349\/revisions\/1375"}],"wp:attachment":[{"href":"https:\/\/strover.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1349"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/strover.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1349"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/strover.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1349"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}