{"id":66268,"date":"2026-02-10T16:15:13","date_gmt":"2026-02-10T15:15:13","guid":{"rendered":"https:\/\/www.idm-energie.at\/?page_id=66268"},"modified":"2026-07-06T13:50:29","modified_gmt":"2026-07-06T11:50:29","slug":"domestic-hot-water","status":"publish","type":"page","link":"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/","title":{"rendered":"Domestic Hot Water"},"content":{"rendered":"<p><div class=\"fusion-fullwidth fullwidth-box fusion-builder-row-1 fusion-flex-container has-pattern-background has-mask-background nonhundred-percent-fullwidth non-hundred-percent-height-scrolling\" style=\"--awb-border-radius-top-left:0px;--awb-border-radius-top-right:0px;--awb-border-radius-bottom-right:0px;--awb-border-radius-bottom-left:0px;--awb-flex-wrap:wrap;\" ><div class=\"fusion-builder-row fusion-row fusion-flex-align-items-flex-start fusion-flex-content-wrap\" style=\"max-width:1185.6px;margin-left: calc(-4% \/ 2 );margin-right: calc(-4% \/ 2 );\"><div class=\"fusion-layout-column fusion_builder_column fusion-builder-column-0 fusion_builder_column_1_1 1_1 fusion-flex-column\" style=\"--awb-bg-size:cover;--awb-width-large:100%;--awb-margin-top-large:0px;--awb-spacing-right-large:1.92%;--awb-margin-bottom-large:20px;--awb-spacing-left-large:1.92%;--awb-width-medium:100%;--awb-order-medium:0;--awb-spacing-right-medium:1.92%;--awb-spacing-left-medium:1.92%;--awb-width-small:100%;--awb-order-small:0;--awb-spacing-right-small:1.92%;--awb-spacing-left-small:1.92%;\"><div class=\"fusion-column-wrapper fusion-column-has-shadow fusion-flex-justify-content-flex-start fusion-content-layout-column\"><nav class=\"fusion-breadcrumbs fusion-breadcrumbs-1\" style=\"--awb-margin-top:1%;--awb-breadcrumb-sep:&#039;\/&#039;;\" aria-label=\"Breadcrumb\"><nav aria-label=\"breadcrumbs\" class=\"rank-math-breadcrumb\"><p><span class=\"last\">Home<\/span><\/p><\/nav><\/nav><div class=\"fusion-title title fusion-title-1 fusion-sep-none fusion-title-center fusion-title-text fusion-title-size-one\" style=\"--awb-margin-top:3%;--awb-margin-bottom:3%;--awb-margin-top-small:10px;--awb-margin-right-small:0px;--awb-margin-bottom-small:10px;--awb-margin-left-small:0px;\"><h1 class=\"fusion-title-heading title-heading-center fusion-responsive-typography-calculated\" style=\"margin:0;text-transform:uppercase;--fontSize:42;line-height:1;\">Domestic Hot Water (DHW) for Heat Pump Systems<\/h1><\/div><div class=\"fusion-text fusion-text-1\"><p>Domestic hot water (DHW) is the part of a heating system that provides hot tap water for showers, baths, handwashing, and kitchens. In a heat pump system, DHW is a separate demand category because it combines temperature requirements, hygiene risk control, and user safety.<\/p>\n<p>This page explains DHW as a heat distribution function within a heat pump system.<\/p>\n<blockquote>\n<p><em>Learn about other components of <a href=\"https:\/\/www.idm-energie.at\/en\/heat-distribution\/\">heat distribution<\/a><\/em><\/p>\n<p><em>Learn about <a href=\"https:\/\/www.idm-energie.at\/en\/heat-pump-technology\/\">heat pump technology<\/a><\/em><\/p>\n<\/blockquote>\n<\/div><\/div><\/div><\/div><\/div><div class=\"fusion-fullwidth fullwidth-box fusion-builder-row-2 fusion-flex-container has-pattern-background has-mask-background nonhundred-percent-fullwidth non-hundred-percent-height-scrolling\" style=\"--awb-border-radius-top-left:0px;--awb-border-radius-top-right:0px;--awb-border-radius-bottom-right:0px;--awb-border-radius-bottom-left:0px;--awb-flex-wrap:wrap;\" ><div class=\"fusion-builder-row fusion-row fusion-flex-align-items-stretch fusion-flex-justify-content-center fusion-flex-content-wrap\" style=\"max-width:1185.6px;margin-left: calc(-4% \/ 2 );margin-right: calc(-4% \/ 2 );\"><div class=\"fusion-layout-column fusion_builder_column fusion-builder-column-1 fusion-flex-column\" style=\"--awb-padding-top:1%;--awb-padding-right:2%;--awb-padding-left:2%;--awb-overflow:hidden;--awb-bg-color:#fff042;--awb-bg-color-hover:#fff042;--awb-bg-size:cover;--awb-border-radius:16px 16px 16px 16px;--awb-width-large:800px;--awb-margin-top-large:0px;--awb-spacing-right-large:2%;--awb-margin-bottom-large:20px;--awb-spacing-left-large:2%;--awb-width-medium:100%;--awb-order-medium:0;--awb-spacing-right-medium:1.92%;--awb-spacing-left-medium:1.92%;--awb-width-small:100%;--awb-order-small:0;--awb-spacing-right-small:1.92%;--awb-spacing-left-small:1.92%;\" data-scroll-devices=\"small-visibility,medium-visibility,large-visibility\"><div class=\"fusion-column-wrapper fusion-column-has-shadow fusion-flex-justify-content-flex-start fusion-content-layout-column\"><div class=\"fusion-title title fusion-title-2 fusion-sep-none fusion-title-center fusion-title-text fusion-title-size-paragraph blink-heading\" style=\"--awb-margin-top-small:10px;--awb-margin-right-small:0px;--awb-margin-bottom-small:10px;--awb-margin-left-small:0px;--awb-font-size:20px;\"><p class=\"fusion-title-heading title-heading-center title-heading-tag fusion-responsive-typography-calculated\" style=\"margin:0;text-transform:uppercase;font-size:1em;--fontSize:20;line-height:1.8;\"><strong>Configure your personalized heat pump system!<\/strong><\/p><\/div><div class=\"fusion-builder-row fusion-builder-row-inner fusion-row fusion-flex-align-items-stretch fusion-flex-justify-content-center fusion-flex-content-wrap\" style=\"--awb-flex-grow:0;--awb-flex-grow-medium:0;--awb-flex-grow-small:0;--awb-flex-shrink:0;--awb-flex-shrink-medium:0;--awb-flex-shrink-small:0;width:104% !important;max-width:104% !important;margin-left: calc(-4% \/ 2 );margin-right: calc(-4% \/ 2 );\"><div class=\"fusion-layout-column fusion_builder_column_inner fusion-builder-nested-column-0 fusion_builder_column_inner_1_1 1_1 fusion-flex-column\" style=\"--awb-bg-size:cover;--awb-width-large:100%;--awb-margin-top-large:0px;--awb-spacing-right-large:1.92%;--awb-margin-bottom-large:-5px;--awb-spacing-left-large:1.92%;--awb-width-medium:100%;--awb-order-medium:0;--awb-spacing-right-medium:1.92%;--awb-spacing-left-medium:1.92%;--awb-width-small:100%;--awb-order-small:0;--awb-spacing-right-small:1.92%;--awb-spacing-left-small:1.92%;\" data-scroll-devices=\"small-visibility,medium-visibility,large-visibility\"><div class=\"fusion-column-wrapper fusion-column-has-shadow fusion-flex-justify-content-flex-start fusion-content-layout-column\"><div class=\"fusion-text fusion-text-2\" style=\"--awb-margin-left:2%;\"><p style=\"text-align: left;\">Plan your heat pump system with iDM Energiesysteme. Discover efficient heating, cooling, and hot water solutions for new buildings, renovations, and modern energy systems. Configure and personalize your iDM heat pump solution in just a few clicks.<\/p>\n<\/div><\/div><\/div><div class=\"fusion-layout-column fusion_builder_column_inner fusion-builder-nested-column-1 fusion_builder_column_inner_2_3 2_3 fusion-flex-column\" style=\"--awb-bg-size:cover;--awb-width-large:66.666666666667%;--awb-margin-top-large:0px;--awb-spacing-right-large:2.88%;--awb-margin-bottom-large:20px;--awb-spacing-left-large:2.88%;--awb-width-medium:100%;--awb-order-medium:0;--awb-spacing-right-medium:1.92%;--awb-spacing-left-medium:1.92%;--awb-width-small:100%;--awb-order-small:0;--awb-spacing-right-small:1.92%;--awb-spacing-left-small:1.92%;\" data-scroll-devices=\"small-visibility,medium-visibility,large-visibility\"><div class=\"fusion-column-wrapper fusion-column-has-shadow fusion-flex-justify-content-flex-start fusion-content-layout-column\"><div class=\"fusion-text fusion-text-3\"><div style=\"display: flex; align-items: center; gap: 15px; flex-wrap: wrap;\">\n<div style=\"display: flex;\">\n<img decoding=\"async\" width=\"150\" height=\"150\" class=\"size-thumbnail wp-image-73518 aligncenter\" style=\"width: 50px; height: 50px; border-radius: 50%; border: 2px solid #000000;\" src=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/thomas-portrait-150x150.jpg\" alt=\"Thomas Pletzer\" srcset=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/thomas-portrait-66x66.jpg 66w, https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/thomas-portrait-150x150.jpg 150w\" sizes=\"(max-width: 150px) 100vw, 150px\" \/><br \/>\n<img decoding=\"async\" width=\"150\" height=\"150\" class=\"size-thumbnail wp-image-73509 aligncenter\" style=\"width: 50px; height: 50px; border-radius: 50%; border: 2px solid #000000;\" src=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/matthias-portrait-150x150.jpg\" alt=\"Matthias Steiner\" margin-left: -15px; srcset=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/matthias-portrait-66x66.jpg 66w, https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/matthias-portrait-150x150.jpg 150w\" sizes=\"(max-width: 150px) 100vw, 150px\" \/><br \/>\n<img decoding=\"async\" width=\"150\" height=\"150\" class=\"size-thumbnail wp-image-73500 aligncenter\" style=\"width: 50px; height: 50px; border-radius: 50%; border: 2px solid #000000;\" src=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/christian-hutter-portrait-150x150.jpg\" alt=\"Christian Hutter\" margin-left: -15px; srcset=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/christian-hutter-portrait-66x66.jpg 66w, https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/christian-hutter-portrait-150x150.jpg 150w\" sizes=\"(max-width: 150px) 100vw, 150px\" \/><br \/>\n<img decoding=\"async\" width=\"150\" height=\"150\" class=\"size-thumbnail wp-image-73491 aligncenter\" style=\"width: 50px; height: 50px; border-radius: 50%; border: 2px solid #000000;\" src=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/adrian-portrait-150x150.jpg\" alt=\"Adrian Egger\" margin-left: -15px; srcset=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/adrian-portrait-66x66.jpg 66w, https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/adrian-portrait-150x150.jpg 150w\" sizes=\"(max-width: 150px) 100vw, 150px\" \/><\/p>\n<\/div>\n<div style=\"color: #000000; line-height: 0.7; margin-left: 2%;\"><strong style=\"display: block;\">CONNECT WITH OUR EXPERTS<\/strong><br \/>\n<span style=\"opacity: 0.8;\">50+ Years of Heat Pumps Experience<\/span><\/div>\n<\/div>\n<\/div><\/div><\/div><div class=\"fusion-layout-column fusion_builder_column_inner fusion-builder-nested-column-2 fusion_builder_column_inner_1_3 1_3 fusion-flex-column fusion-flex-align-self-center\" style=\"--awb-bg-size:cover;--awb-width-large:33.333333333333%;--awb-margin-top-large:0px;--awb-spacing-right-large:5.76%;--awb-margin-bottom-large:20px;--awb-spacing-left-large:5.76%;--awb-width-medium:100%;--awb-order-medium:0;--awb-spacing-right-medium:1.92%;--awb-spacing-left-medium:1.92%;--awb-width-small:100%;--awb-order-small:0;--awb-spacing-right-small:1.92%;--awb-spacing-left-small:1.92%;\" data-scroll-devices=\"small-visibility,medium-visibility,large-visibility\"><div class=\"fusion-column-wrapper fusion-column-has-shadow fusion-flex-justify-content-center fusion-content-layout-column\"><div style=\"text-align:center;\"><a class=\"fusion-button button-flat fusion-button-default-size button-default fusion-button-default button-1 fusion-button-default-span fusion-button-default-type\" target=\"_self\" href=\"https:\/\/konfigurator.myidm.at\/#\/?lang=EN\" rel=\"noopener\"><span class=\"fusion-button-text awb-button__text awb-button__text--default\">Configure Now!<\/span><\/a><\/div><\/div><\/div><\/div><\/div><\/div><\/div><\/div><div class=\"fusion-fullwidth fullwidth-box fusion-builder-row-3 fusion-flex-container has-pattern-background has-mask-background nonhundred-percent-fullwidth non-hundred-percent-height-scrolling\" style=\"--awb-border-radius-top-left:0px;--awb-border-radius-top-right:0px;--awb-border-radius-bottom-right:0px;--awb-border-radius-bottom-left:0px;--awb-flex-wrap:wrap;\" ><div class=\"fusion-builder-row fusion-row fusion-flex-align-items-flex-start fusion-flex-content-wrap\" style=\"max-width:1185.6px;margin-left: calc(-4% \/ 2 );margin-right: calc(-4% \/ 2 );\"><div class=\"fusion-layout-column fusion_builder_column fusion-builder-column-2 fusion_builder_column_1_1 1_1 fusion-flex-column\" style=\"--awb-bg-size:cover;--awb-width-large:100%;--awb-margin-top-large:0px;--awb-spacing-right-large:1.92%;--awb-margin-bottom-large:20px;--awb-spacing-left-large:1.92%;--awb-width-medium:100%;--awb-order-medium:0;--awb-spacing-right-medium:1.92%;--awb-spacing-left-medium:1.92%;--awb-width-small:100%;--awb-order-small:0;--awb-spacing-right-small:1.92%;--awb-spacing-left-small:1.92%;\"><div class=\"fusion-column-wrapper fusion-column-has-shadow fusion-flex-justify-content-flex-start fusion-content-layout-column\"><div class=\"fusion-text fusion-text-4\"><p><strong>Facts and figures<\/strong><\/p>\n<ul>\n<li><strong>DHW is a major household energy use.<\/strong> A REHVA journal article notes that hot water production and legionella prevention in DHW systems account for around 17% of total energy demand of German households (based on Eurostat figures discussed in that article).<\/li>\n<li><strong>Legionella growth is temperature-sensitive.<\/strong> World Health Organization guidance highlights keeping water temperatures outside typical growth ranges and notes, for hot water systems, water leaving heaters above 60\u00b0C and maintaining above 50\u00b0C through associated pipework as part of control strategies.<\/li>\n<li><strong>Many systems store hotter than the water you actually use.<\/strong> An International Energy Agency Heat Pumping Technologies report notes DHW is often produced\/stored\/distributed at 55\u201360\u00b0C for legionella control, while desired use temperature at high-risk taps (e.g., showers) is often 30\u201340\u00b0C\u2014which is why mixing\/tempering is common.<\/li>\n<li><strong>Heat pumps may need a DHW \u201cboost\u201d mode.<\/strong> Sustainable Energy Authority of Ireland guidance notes some heat pumps cannot heat a cylinder to 60\u00b0C, and in those cases a booster heater\/immersion is often used for disinfection cycles.<\/li>\n<\/ul>\n<\/div><\/div><\/div><\/div><\/div><div class=\"fusion-fullwidth fullwidth-box fusion-builder-row-4 fusion-flex-container has-pattern-background has-mask-background nonhundred-percent-fullwidth non-hundred-percent-height-scrolling\" style=\"--awb-border-radius-top-left:0px;--awb-border-radius-top-right:0px;--awb-border-radius-bottom-right:0px;--awb-border-radius-bottom-left:0px;--awb-flex-wrap:wrap;\" ><div class=\"fusion-builder-row fusion-row fusion-flex-align-items-flex-start fusion-flex-content-wrap\" style=\"max-width:1185.6px;margin-left: calc(-4% \/ 2 );margin-right: calc(-4% \/ 2 );\"><div class=\"fusion-layout-column fusion_builder_column fusion-builder-column-3 fusion_builder_column_1_1 1_1 fusion-flex-column\" style=\"--awb-bg-size:cover;--awb-width-large:100%;--awb-margin-top-large:0px;--awb-spacing-right-large:1.92%;--awb-margin-bottom-large:20px;--awb-spacing-left-large:1.92%;--awb-width-medium:100%;--awb-order-medium:0;--awb-spacing-right-medium:1.92%;--awb-spacing-left-medium:1.92%;--awb-width-small:100%;--awb-order-small:0;--awb-spacing-right-small:1.92%;--awb-spacing-left-small:1.92%;\"><div class=\"fusion-column-wrapper fusion-column-has-shadow fusion-flex-justify-content-flex-start fusion-content-layout-column\"><div class=\"fusion-text fusion-text-5\">\n<\/div><div class=\"fusion-text fusion-text-6\"><div id=\"ez-toc-container\" class=\"ez-toc-v2_0_85 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/#What_%E2%80%9Cdomestic_hot_water%E2%80%9D_means\" >What \u201cdomestic hot water\u201d means<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/#Why_DHW_matters_for_heat_pumps\" >Why DHW matters for heat pumps<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/#Key_terms_and_system_boundaries\" >Key terms and system boundaries<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/#DHW_hygiene_and_temperature_control\" >DHW hygiene and temperature control<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/#User_safety_scalding_risk_and_temperature_limiting\" >User safety: scalding risk and temperature limiting<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/#Main_DHW_system_configurations\" >Main DHW system configurations<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/#Integration_with_other_distribution_components\" >Integration with other distribution components<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/#Core_components_in_a_DHW_system\" >Core components in a DHW system<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/#What_influences_DHW_performance_and_efficiency\" >What influences DHW performance and efficiency<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/#Integration_with_other_distribution_components-2\" >Integration with other distribution components<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/#Frequently_Asked_Questions_FAQs\" >Frequently Asked Questions (FAQs)<\/a><\/li><\/ul><\/nav><\/div>\n<h2><span class=\"ez-toc-section\" id=\"What_%E2%80%9Cdomestic_hot_water%E2%80%9D_means\"><\/span>What \u201cdomestic hot water\u201d means<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Domestic hot water is sanitary hot water delivered at outlets in a building for everyday use. In a heat pump system, DHW is usually produced by heating water in a storage cylinder\/tank or via instantaneous heating (depending on system concept).<\/p>\n<p><strong>What this is<\/strong><\/p>\n<ul>\n<li>A heat distribution demand (separate from space heating)<\/li>\n<li>A system function shaped by hygiene (microbiological risk) and safety (scald prevention)<\/li>\n<li>Often a load that requires higher temperatures than low-temperature space heating<\/li>\n<\/ul>\n<p><strong>What this is not<\/strong><\/p>\n<ul>\n<li>A different heat pump technology<\/li>\n<li>A single universal temperature rule (requirements vary by building type, risk level, and national regulations)<\/li>\n<\/ul>\n<\/div><div class=\"fusion-image-element\" style=\"text-align:center;--awb-margin-top:2%;--awb-margin-bottom:2%;--awb-caption-title-font-family:var(--h2_typography-font-family);--awb-caption-title-font-weight:var(--h2_typography-font-weight);--awb-caption-title-font-style:var(--h2_typography-font-style);--awb-caption-title-size:var(--h2_typography-font-size);--awb-caption-title-transform:var(--h2_typography-text-transform);--awb-caption-title-line-height:var(--h2_typography-line-height);--awb-caption-title-letter-spacing:var(--h2_typography-letter-spacing);\"><span class=\" fusion-imageframe imageframe-none imageframe-1 hover-type-none\" style=\"border:3px solid #333333;\"><img decoding=\"async\" width=\"1024\" height=\"559\" alt=\"Domestic Hot Water as a component in Heat Pump System for Heat Distribution\" title=\"domestic-hot-water\" src=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/02\/domestic-hot-water-1024x559.webp\" class=\"img-responsive wp-image-66283\" srcset=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/02\/domestic-hot-water-200x109.webp 200w, https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/02\/domestic-hot-water-400x218.webp 400w, https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/02\/domestic-hot-water-600x327.webp 600w, https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/02\/domestic-hot-water-800x436.webp 800w, https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/02\/domestic-hot-water-1200x655.webp 1200w\" sizes=\"(max-width: 1024px) 100vw, (max-width: 640px) 100vw, 1200px\" \/><\/span><\/div><div class=\"fusion-text fusion-text-7\"><h2><span class=\"ez-toc-section\" id=\"Why_DHW_matters_for_heat_pumps\"><\/span>Why DHW matters for heat pumps<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>DHW often drives different operating conditions than space heating:<\/p>\n<ul>\n<li>Higher temperature targets than many space-heating emitters<\/li>\n<li>Short, concentrated demand peaks (showers\/baths)<\/li>\n<li>Hygiene control needs (temperature\/time strategies or other measures)<\/li>\n<\/ul>\n<p>This is why DHW is commonly treated as its own operating mode in heat pump system design and control logic.<\/p>\n<\/div><div class=\"fusion-text fusion-text-8\"><h2><span class=\"ez-toc-section\" id=\"Key_terms_and_system_boundaries\"><\/span>Key terms and system boundaries<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>A simple boundary helps avoid confusion:<\/p>\n<ul>\n<li><strong>Heat generation:<\/strong> the heat pump produces heat (and may have a booster heater for DHW cycles)<\/li>\n<li><strong>Heat distribution (DHW):<\/strong> cylinder\/tank, pipes, circulation (if used), mixing\/tempering devices, valves, safety components<\/li>\n<li><strong>Control:<\/strong> priority switching (space heat vs DHW), timers\/sensors, disinfection cycle scheduling, temperature limiting logic<\/li>\n<\/ul>\n<\/div><div class=\"fusion-text fusion-text-9\"><h2><span class=\"ez-toc-section\" id=\"DHW_hygiene_and_temperature_control\"><\/span>DHW hygiene and temperature control<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>A core reason DHW is treated differently is legionella risk management.<\/p>\n<ul>\n<li>WHO guidance describes temperature as a key control lever and references hot water leaving heaters at or above ~60\u00b0C and maintaining above ~50\u00b0C in pipework as part of control strategies.<\/li>\n<li>European Centre for Disease Prevention and Control technical guidance similarly discusses reduced colonisation at higher hot-water temperatures and highlights approaches such as circulating at ~60\u00b0C with \u226550\u201355\u00b0C at outlets (or before thermostatic mixing).<\/li>\n<\/ul>\n<\/div><div class=\"fusion-text fusion-text-10\"><h2><span class=\"ez-toc-section\" id=\"User_safety_scalding_risk_and_temperature_limiting\"><\/span>User safety: scalding risk and temperature limiting<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Hygiene control often pushes storage\/distribution temperatures upward, while user safety pushes outlet temperatures downward.<\/p>\n<ul>\n<li>UK safety guidance notes the scalding risk can become significant for vulnerable users and mentions thermostatic mixing valves (TMVs) as a control method in relevant settings.<\/li>\n<\/ul>\n<p><strong>Practical meaning:<\/strong> many systems store water at higher temperatures for hygiene control, then temper it at the point of use to a safer delivery temperature\u2014while keeping the \u201chot side\u201d hot enough to manage microbial risk.<\/p>\n<\/div><div class=\"fusion-text fusion-text-11\"><h2><span class=\"ez-toc-section\" id=\"Main_DHW_system_configurations\"><\/span>Main DHW system configurations<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>DHW concepts can be grouped by how hot water is prepared and delivered.<\/p>\n<h3>Storage DHW (cylinder \/ tank)<\/h3>\n<ul>\n<li>Water is heated and stored in a cylinder.<\/li>\n<li>Supports peak demand by drawing from stored volume.<\/li>\n<li>Often paired with scheduled high-temperature cycles (depending on risk strategy and system capability).<\/li>\n<\/ul>\n<h3>Instantaneous DHW (on-demand)<\/h3>\n<ul>\n<li>Hot water is produced when a tap opens (using a heat exchanger).<\/li>\n<li>Can reduce stored hot water volume, but still needs hygiene and safety management consistent with local rules and the overall system concept.<\/li>\n<\/ul>\n<h3>DHW circulation (recirculation loop) vs non-circulated<\/h3>\n<ul>\n<li>A circulation loop reduces waiting time and can help maintain temperature in larger buildings, but it also increases heat loss from pipework and adds a temperature-control requirement.<\/li>\n<li>Some building guidance discusses maintaining circulation temperatures in a 50\u201355\u00b0C band as part of legionella control strategy (context-dependent).<\/li>\n<\/ul>\n<\/div><div class=\"fusion-text fusion-text-12\"><h2><span class=\"ez-toc-section\" id=\"Integration_with_other_distribution_components\"><\/span>Integration with other distribution components<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Radiators often appear in systems that include additional distribution components:<\/p>\n<ul>\n<li><strong>Radiators + <a href=\"https:\/\/www.idm-energie.at\/en\/heat-distribution\/underfloor-heating\/\">underfloor heating<\/a> (mixed emitter systems):<\/strong> usually needs clear temperature management (often with a mixing concept)<\/li>\n<li><strong>Radiators + domestic hot water (DHW):<\/strong> DHW has different temperature and control priorities than space heating<\/li>\n<li><strong>Multiple zones:<\/strong> increases the importance of stable hydraulics and good control logic<\/li>\n<li><strong>Hydraulic separation or buffering:<\/strong> may be used to stabilize flows and operating behavior in some system layouts (depends on topology, zoning, and control strategy)<\/li>\n<\/ul>\n<\/div><div class=\"fusion-text fusion-text-13\"><h2><span class=\"ez-toc-section\" id=\"Core_components_in_a_DHW_system\"><\/span>Core components in a DHW system<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>A typical DHW setup includes:<\/p>\n<ul>\n<li><strong>Heat source interface:<\/strong> coil\/heat exchanger connected to the heat pump circuit<\/li>\n<li><strong>Storage cylinder \/ tank<\/strong> (if storage-based)<\/li>\n<li><strong>Distribution pipework<\/strong> (hot, cold, and sometimes a circulation return)<\/li>\n<li><strong>Circulation pump<\/strong> (if a recirculation loop is used)<\/li>\n<li><strong>Mixing\/tempering valve<\/strong> (to limit outlet temperature and improve safety)<\/li>\n<li><strong>Safety components:<\/strong> temperature\/pressure relief, expansion provisions, backflow protection (exact requirements depend on national codes)<\/li>\n<li><strong>Sensors and controls:<\/strong> cylinder temperature sensor(s), timers, disinfection cycle control, priority logic<\/li>\n<\/ul>\n<\/div><div class=\"fusion-text fusion-text-14\"><h2><span class=\"ez-toc-section\" id=\"What_influences_DHW_performance_and_efficiency\"><\/span>What influences DHW performance and efficiency<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>These factors show up across most DHW discussions:<\/p>\n<ol>\n<li><strong>Temperature targets:<\/strong> Higher DHW temperatures generally increase the heat pump\u2019s temperature lift requirement and can reduce efficiency relative to low-temperature space heating.<\/li>\n<li><strong>Storage and distribution losses:<\/strong> Tanks and long pipe runs lose heat continuously; circulation loops can increase losses if not well controlled.<\/li>\n<li><strong>System capability at high temperature:<\/strong> Some heat pump systems rely on a booster heater\/immersion for periodic high-temperature cycles.<\/li>\n<li><strong>Demand profile:<\/strong> Short peaks (showers) and usage timing affect how often the system needs to reheat the tank.<\/li>\n<li><strong>Hygiene strategy and monitoring:<\/strong> Temperature control is a common approach; cleaning, flushing, and stagnation reduction are also discussed in public health guidance.<\/li>\n<\/ol>\n<\/div><div class=\"fusion-text fusion-text-15\"><h2><span class=\"ez-toc-section\" id=\"Integration_with_other_distribution_components-2\"><\/span>Integration with other distribution components<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>DHW interacts with the rest of the heating system:<\/p>\n<ul>\n<li><strong>DHW + space heating:<\/strong> many controls give DHW priority during reheating, then return to space heating.<\/li>\n<li><strong>DHW + buffer\/storage concepts:<\/strong> DHW cylinders are different from space-heating buffer tanks, but both are storage elements that affect cycling and stability.<\/li>\n<li><strong>DHW + mixed-temperature systems:<\/strong> mixing\/tempering is common to balance hygiene temperatures with safe outlet delivery.<\/li>\n<\/ul>\n<p>The other components of heat distribution in heat pump system include:<\/p>\n<blockquote>\n<p><a href=\"https:\/\/www.idm-energie.at\/en\/heat-distribution\/underfloor-heating\/\"><em>Underfloor Heating<\/em><\/a><\/p>\n<p><a href=\"https:\/\/www.idm-energie.at\/en\/heat-distribution\/radiators\/\"><em>Radiators<\/em><\/a><\/p>\n<\/blockquote>\n<\/div><\/div><\/div><\/div><\/div><div class=\"fusion-fullwidth fullwidth-box fusion-builder-row-5 fusion-flex-container has-pattern-background has-mask-background nonhundred-percent-fullwidth non-hundred-percent-height-scrolling\" style=\"--awb-border-radius-top-left:0px;--awb-border-radius-top-right:0px;--awb-border-radius-bottom-right:0px;--awb-border-radius-bottom-left:0px;--awb-flex-wrap:wrap;\" ><div class=\"fusion-builder-row fusion-row fusion-flex-align-items-stretch fusion-flex-justify-content-center fusion-flex-content-wrap\" style=\"max-width:1185.6px;margin-left: calc(-4% \/ 2 );margin-right: calc(-4% \/ 2 );\"><div class=\"fusion-layout-column fusion_builder_column fusion-builder-column-4 fusion-flex-column\" style=\"--awb-padding-top:1%;--awb-padding-right:2%;--awb-padding-left:2%;--awb-overflow:hidden;--awb-bg-color:#fff042;--awb-bg-color-hover:#fff042;--awb-bg-size:cover;--awb-border-radius:16px 16px 16px 16px;--awb-width-large:800px;--awb-margin-top-large:0px;--awb-spacing-right-large:2%;--awb-margin-bottom-large:20px;--awb-spacing-left-large:2%;--awb-width-medium:100%;--awb-order-medium:0;--awb-spacing-right-medium:1.92%;--awb-spacing-left-medium:1.92%;--awb-width-small:100%;--awb-order-small:0;--awb-spacing-right-small:1.92%;--awb-spacing-left-small:1.92%;\" data-scroll-devices=\"small-visibility,medium-visibility,large-visibility\"><div class=\"fusion-column-wrapper fusion-column-has-shadow fusion-flex-justify-content-flex-start fusion-content-layout-column\"><div class=\"fusion-title title fusion-title-3 fusion-sep-none fusion-title-center fusion-title-text fusion-title-size-paragraph blink-heading\" style=\"--awb-margin-top-small:10px;--awb-margin-right-small:0px;--awb-margin-bottom-small:10px;--awb-margin-left-small:0px;--awb-font-size:20px;\"><p class=\"fusion-title-heading title-heading-center title-heading-tag fusion-responsive-typography-calculated\" style=\"margin:0;text-transform:uppercase;font-size:1em;--fontSize:20;line-height:1.8;\"><strong>Configure your personalized heat pump system!<\/strong><\/p><\/div><div class=\"fusion-builder-row fusion-builder-row-inner fusion-row fusion-flex-align-items-stretch fusion-flex-justify-content-center fusion-flex-content-wrap\" style=\"--awb-flex-grow:0;--awb-flex-grow-medium:0;--awb-flex-grow-small:0;--awb-flex-shrink:0;--awb-flex-shrink-medium:0;--awb-flex-shrink-small:0;width:104% !important;max-width:104% !important;margin-left: calc(-4% \/ 2 );margin-right: calc(-4% \/ 2 );\"><div class=\"fusion-layout-column fusion_builder_column_inner fusion-builder-nested-column-3 fusion_builder_column_inner_1_1 1_1 fusion-flex-column\" style=\"--awb-bg-size:cover;--awb-width-large:100%;--awb-margin-top-large:0px;--awb-spacing-right-large:1.92%;--awb-margin-bottom-large:-5px;--awb-spacing-left-large:1.92%;--awb-width-medium:100%;--awb-order-medium:0;--awb-spacing-right-medium:1.92%;--awb-spacing-left-medium:1.92%;--awb-width-small:100%;--awb-order-small:0;--awb-spacing-right-small:1.92%;--awb-spacing-left-small:1.92%;\" data-scroll-devices=\"small-visibility,medium-visibility,large-visibility\"><div class=\"fusion-column-wrapper fusion-column-has-shadow fusion-flex-justify-content-flex-start fusion-content-layout-column\"><div class=\"fusion-text fusion-text-16\" style=\"--awb-margin-left:2%;\"><p style=\"text-align: left;\">Plan your heat pump system with iDM Energiesysteme. Discover efficient heating, cooling, and hot water solutions for new buildings, renovations, and modern energy systems. Configure and personalize your iDM heat pump solution in just a few clicks.<\/p>\n<\/div><\/div><\/div><div class=\"fusion-layout-column fusion_builder_column_inner fusion-builder-nested-column-4 fusion_builder_column_inner_2_3 2_3 fusion-flex-column\" style=\"--awb-bg-size:cover;--awb-width-large:66.666666666667%;--awb-margin-top-large:0px;--awb-spacing-right-large:2.88%;--awb-margin-bottom-large:20px;--awb-spacing-left-large:2.88%;--awb-width-medium:100%;--awb-order-medium:0;--awb-spacing-right-medium:1.92%;--awb-spacing-left-medium:1.92%;--awb-width-small:100%;--awb-order-small:0;--awb-spacing-right-small:1.92%;--awb-spacing-left-small:1.92%;\" data-scroll-devices=\"small-visibility,medium-visibility,large-visibility\"><div class=\"fusion-column-wrapper fusion-column-has-shadow fusion-flex-justify-content-flex-start fusion-content-layout-column\"><div class=\"fusion-text fusion-text-17\"><div style=\"display: flex; align-items: center; gap: 15px; flex-wrap: wrap;\">\n<div style=\"display: flex;\">\n<img decoding=\"async\" width=\"150\" height=\"150\" class=\"size-thumbnail wp-image-73518 aligncenter\" style=\"width: 50px; height: 50px; border-radius: 50%; border: 2px solid #000000;\" src=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/thomas-portrait-150x150.jpg\" alt=\"Thomas Pletzer\" srcset=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/thomas-portrait-66x66.jpg 66w, https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/thomas-portrait-150x150.jpg 150w\" sizes=\"(max-width: 150px) 100vw, 150px\" \/><br \/>\n<img decoding=\"async\" width=\"150\" height=\"150\" class=\"size-thumbnail wp-image-73509 aligncenter\" style=\"width: 50px; height: 50px; border-radius: 50%; border: 2px solid #000000;\" src=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/matthias-portrait-150x150.jpg\" alt=\"Matthias Steiner\" margin-left: -15px; srcset=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/matthias-portrait-66x66.jpg 66w, https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/matthias-portrait-150x150.jpg 150w\" sizes=\"(max-width: 150px) 100vw, 150px\" \/><br \/>\n<img decoding=\"async\" width=\"150\" height=\"150\" class=\"size-thumbnail wp-image-73500 aligncenter\" style=\"width: 50px; height: 50px; border-radius: 50%; border: 2px solid #000000;\" src=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/christian-hutter-portrait-150x150.jpg\" alt=\"Christian Hutter\" margin-left: -15px; srcset=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/christian-hutter-portrait-66x66.jpg 66w, https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/christian-hutter-portrait-150x150.jpg 150w\" sizes=\"(max-width: 150px) 100vw, 150px\" \/><br \/>\n<img decoding=\"async\" width=\"150\" height=\"150\" class=\"size-thumbnail wp-image-73491 aligncenter\" style=\"width: 50px; height: 50px; border-radius: 50%; border: 2px solid #000000;\" src=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/adrian-portrait-150x150.jpg\" alt=\"Adrian Egger\" margin-left: -15px; srcset=\"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/adrian-portrait-66x66.jpg 66w, https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/07\/adrian-portrait-150x150.jpg 150w\" sizes=\"(max-width: 150px) 100vw, 150px\" \/><\/p>\n<\/div>\n<div style=\"color: #000000; line-height: 0.7; margin-left: 2%;\"><strong style=\"display: block;\">CONNECT WITH OUR EXPERTS<\/strong><br \/>\n<span style=\"opacity: 0.8;\">50+ Years of Heat Pumps Experience<\/span><\/div>\n<\/div>\n<\/div><\/div><\/div><div class=\"fusion-layout-column fusion_builder_column_inner fusion-builder-nested-column-5 fusion_builder_column_inner_1_3 1_3 fusion-flex-column fusion-flex-align-self-center\" style=\"--awb-bg-size:cover;--awb-width-large:33.333333333333%;--awb-margin-top-large:0px;--awb-spacing-right-large:5.76%;--awb-margin-bottom-large:20px;--awb-spacing-left-large:5.76%;--awb-width-medium:100%;--awb-order-medium:0;--awb-spacing-right-medium:1.92%;--awb-spacing-left-medium:1.92%;--awb-width-small:100%;--awb-order-small:0;--awb-spacing-right-small:1.92%;--awb-spacing-left-small:1.92%;\" data-scroll-devices=\"small-visibility,medium-visibility,large-visibility\"><div class=\"fusion-column-wrapper fusion-column-has-shadow fusion-flex-justify-content-center fusion-content-layout-column\"><div style=\"text-align:center;\"><a class=\"fusion-button button-flat fusion-button-default-size button-default fusion-button-default button-2 fusion-button-default-span fusion-button-default-type\" target=\"_self\" href=\"https:\/\/konfigurator.myidm.at\/#\/?lang=EN\" rel=\"noopener\"><span class=\"fusion-button-text awb-button__text awb-button__text--default\">Configure Now!<\/span><\/a><\/div><\/div><\/div><\/div><\/div><\/div><\/div><\/div><div class=\"fusion-fullwidth fullwidth-box fusion-builder-row-6 fusion-flex-container has-pattern-background has-mask-background nonhundred-percent-fullwidth non-hundred-percent-height-scrolling\" style=\"--awb-border-radius-top-left:0px;--awb-border-radius-top-right:0px;--awb-border-radius-bottom-right:0px;--awb-border-radius-bottom-left:0px;--awb-flex-wrap:wrap;\" ><div class=\"fusion-builder-row fusion-row fusion-flex-align-items-flex-start fusion-flex-content-wrap\" style=\"max-width:1185.6px;margin-left: calc(-4% \/ 2 );margin-right: calc(-4% \/ 2 );\"><div class=\"fusion-layout-column fusion_builder_column fusion-builder-column-5 fusion_builder_column_1_1 1_1 fusion-flex-column\" style=\"--awb-bg-size:cover;--awb-width-large:100%;--awb-margin-top-large:0px;--awb-spacing-right-large:1.92%;--awb-margin-bottom-large:20px;--awb-spacing-left-large:1.92%;--awb-width-medium:100%;--awb-order-medium:0;--awb-spacing-right-medium:1.92%;--awb-spacing-left-medium:1.92%;--awb-width-small:100%;--awb-order-small:0;--awb-spacing-right-small:1.92%;--awb-spacing-left-small:1.92%;\"><div class=\"fusion-column-wrapper fusion-column-has-shadow fusion-flex-justify-content-flex-start fusion-content-layout-column\"><div class=\"fusion-text fusion-text-18 fusion-text-no-margin\" style=\"--awb-margin-bottom:5px;\"><h2><span class=\"ez-toc-section\" id=\"Frequently_Asked_Questions_FAQs\"><\/span>Frequently Asked Questions (FAQs)<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<\/div><div class=\"accordian fusion-accordian\" style=\"--awb-border-size:1px;--awb-icon-size:16px;--awb-content-font-size:15px;--awb-icon-alignment:right;--awb-hover-color:#f9f9fb;--awb-border-color:#e2e2e2;--awb-background-color:#ffffff;--awb-divider-color:#e2e2e2;--awb-divider-hover-color:#e2e2e2;--awb-icon-color:#009fe3;--awb-title-color:#59682f;--awb-content-color:#3f3f3f;--awb-icon-box-color:#212934;--awb-toggle-hover-accent-color:#009fe3;--awb-title-font-family:&quot;Aller&quot;;--awb-title-font-weight:700;--awb-title-font-style:normal;--awb-title-font-size:18px;--awb-content-font-family:&quot;Aller&quot;;--awb-content-font-style:normal;--awb-content-font-weight:400;\"><div class=\"panel-group fusion-toggle-icon-right fusion-toggle-icon-unboxed\" id=\"accordion-66268-1\"><div class=\"fusion-panel panel-default panel-2ff975d2ce0b96feb fusion-toggle-no-divider fusion-toggle-boxed-mode\" style=\"--awb-title-color:#59682f;--awb-content-color:#3f3f3f;\"><div class=\"panel-heading\"><h4 class=\"panel-title toggle\" id=\"toggle_2ff975d2ce0b96feb\"><a aria-expanded=\"false\" aria-controls=\"2ff975d2ce0b96feb\" role=\"button\" data-toggle=\"collapse\" data-parent=\"#accordion-66268-1\" data-target=\"#2ff975d2ce0b96feb\" href=\"#2ff975d2ce0b96feb\"><span class=\"fusion-toggle-icon-wrapper\" aria-hidden=\"true\"><i class=\"fa-fusion-box active-icon awb-icon-minus\" aria-hidden=\"true\"><\/i><i class=\"fa-fusion-box inactive-icon awb-icon-plus\" aria-hidden=\"true\"><\/i><\/span><span class=\"fusion-toggle-heading\">1. What is domestic hot water (DHW) in a heat pump system?<\/span><\/a><\/h4><\/div><div id=\"2ff975d2ce0b96feb\" class=\"panel-collapse collapse \" aria-labelledby=\"toggle_2ff975d2ce0b96feb\"><div class=\"panel-body toggle-content fusion-clearfix\">\n<p>DHW is hot tap water for showers, baths, and sinks. In a heat pump system it is treated as a separate demand because it combines temperature targets, hygiene control, and user safety.<\/p>\n<\/div><\/div><\/div><div class=\"fusion-panel panel-default panel-799cfc1817842f826 fusion-toggle-no-divider fusion-toggle-boxed-mode\" style=\"--awb-title-color:#59682f;--awb-content-color:#3f3f3f;\"><div class=\"panel-heading\"><h4 class=\"panel-title toggle\" id=\"toggle_799cfc1817842f826\"><a aria-expanded=\"false\" aria-controls=\"799cfc1817842f826\" role=\"button\" data-toggle=\"collapse\" data-parent=\"#accordion-66268-1\" data-target=\"#799cfc1817842f826\" href=\"#799cfc1817842f826\"><span class=\"fusion-toggle-icon-wrapper\" aria-hidden=\"true\"><i class=\"fa-fusion-box active-icon awb-icon-minus\" aria-hidden=\"true\"><\/i><i class=\"fa-fusion-box inactive-icon awb-icon-plus\" aria-hidden=\"true\"><\/i><\/span><span class=\"fusion-toggle-heading\">2. Why is DHW often stored hotter than the water used at the tap?<\/span><\/a><\/h4><\/div><div id=\"799cfc1817842f826\" class=\"panel-collapse collapse \" aria-labelledby=\"toggle_799cfc1817842f826\"><div class=\"panel-body toggle-content fusion-clearfix\">\n<p data-pm-slice=\"1 1 &#091;&#093;\">Because hygiene control often relies on higher storage\/distribution temperatures, while users typically want lower temperatures at showers and sinks\u2014so tempering\/mixing is used.<\/p>\n<\/div><\/div><\/div><div class=\"fusion-panel panel-default panel-1a929012b5c5d7031 fusion-toggle-no-divider fusion-toggle-boxed-mode\" style=\"--awb-title-color:#59682f;--awb-content-color:#3f3f3f;\"><div class=\"panel-heading\"><h4 class=\"panel-title toggle\" id=\"toggle_1a929012b5c5d7031\"><a aria-expanded=\"false\" aria-controls=\"1a929012b5c5d7031\" role=\"button\" data-toggle=\"collapse\" data-parent=\"#accordion-66268-1\" data-target=\"#1a929012b5c5d7031\" href=\"#1a929012b5c5d7031\"><span class=\"fusion-toggle-icon-wrapper\" aria-hidden=\"true\"><i class=\"fa-fusion-box active-icon awb-icon-minus\" aria-hidden=\"true\"><\/i><i class=\"fa-fusion-box inactive-icon awb-icon-plus\" aria-hidden=\"true\"><\/i><\/span><span class=\"fusion-toggle-heading\">3. What temperatures are commonly referenced for legionella control?<\/span><\/a><\/h4><\/div><div id=\"1a929012b5c5d7031\" class=\"panel-collapse collapse \" aria-labelledby=\"toggle_1a929012b5c5d7031\"><div class=\"panel-body toggle-content fusion-clearfix\">\n<p>WHO guidance references hot water leaving heaters at ~60\u00b0C and maintaining &gt;50\u00b0C in pipework as part of temperature control strategies; ECDC technical guidance discusses similar ranges in control contexts. Always align with local regulations and risk assessment.<\/p>\n<\/div><\/div><\/div><div class=\"fusion-panel panel-default panel-a6a2712bb72dcb752 fusion-toggle-no-divider fusion-toggle-boxed-mode\" style=\"--awb-title-color:#59682f;--awb-content-color:#3f3f3f;\"><div class=\"panel-heading\"><h4 class=\"panel-title toggle\" id=\"toggle_a6a2712bb72dcb752\"><a aria-expanded=\"false\" aria-controls=\"a6a2712bb72dcb752\" role=\"button\" data-toggle=\"collapse\" data-parent=\"#accordion-66268-1\" data-target=\"#a6a2712bb72dcb752\" href=\"#a6a2712bb72dcb752\"><span class=\"fusion-toggle-icon-wrapper\" aria-hidden=\"true\"><i class=\"fa-fusion-box active-icon awb-icon-minus\" aria-hidden=\"true\"><\/i><i class=\"fa-fusion-box inactive-icon awb-icon-plus\" aria-hidden=\"true\"><\/i><\/span><span class=\"fusion-toggle-heading\">4. Why do some heat pump systems use an electric \u201cboost\u201d for DHW?<\/span><\/a><\/h4><\/div><div id=\"a6a2712bb72dcb752\" class=\"panel-collapse collapse \" aria-labelledby=\"toggle_a6a2712bb72dcb752\"><div class=\"panel-body toggle-content fusion-clearfix\">\n<p>Some heat pumps cannot reach the highest cylinder temperatures needed for periodic disinfection cycles, so a booster heater\/immersion may be used.<\/p>\n<\/div><\/div><\/div><div class=\"fusion-panel panel-default panel-522a8e260d8203d8f fusion-toggle-no-divider fusion-toggle-boxed-mode\" style=\"--awb-title-color:#59682f;--awb-content-color:#3f3f3f;\"><div class=\"panel-heading\"><h4 class=\"panel-title toggle\" id=\"toggle_522a8e260d8203d8f\"><a aria-expanded=\"false\" aria-controls=\"522a8e260d8203d8f\" role=\"button\" data-toggle=\"collapse\" data-parent=\"#accordion-66268-1\" data-target=\"#522a8e260d8203d8f\" href=\"#522a8e260d8203d8f\"><span class=\"fusion-toggle-icon-wrapper\" aria-hidden=\"true\"><i class=\"fa-fusion-box active-icon awb-icon-minus\" aria-hidden=\"true\"><\/i><i class=\"fa-fusion-box inactive-icon awb-icon-plus\" aria-hidden=\"true\"><\/i><\/span><span class=\"fusion-toggle-heading\">5. What is the role of a mixing valve in DHW?<\/span><\/a><\/h4><\/div><div id=\"522a8e260d8203d8f\" class=\"panel-collapse collapse \" aria-labelledby=\"toggle_522a8e260d8203d8f\"><div class=\"panel-body toggle-content fusion-clearfix\">\n<p data-pm-slice=\"1 1 &#091;&#093;\">A mixing (tempering) valve blends hot and cold water to deliver a safer outlet temperature while the storage side can remain hotter for hygiene control.<\/p>\n<\/div><\/div><\/div><div class=\"fusion-panel panel-default panel-6cee403cca43a73dc fusion-toggle-no-divider fusion-toggle-boxed-mode\" style=\"--awb-title-color:#59682f;--awb-content-color:#3f3f3f;\"><div class=\"panel-heading\"><h4 class=\"panel-title toggle\" id=\"toggle_6cee403cca43a73dc\"><a aria-expanded=\"false\" aria-controls=\"6cee403cca43a73dc\" role=\"button\" data-toggle=\"collapse\" data-parent=\"#accordion-66268-1\" data-target=\"#6cee403cca43a73dc\" href=\"#6cee403cca43a73dc\"><span class=\"fusion-toggle-icon-wrapper\" aria-hidden=\"true\"><i class=\"fa-fusion-box active-icon awb-icon-minus\" aria-hidden=\"true\"><\/i><i class=\"fa-fusion-box inactive-icon awb-icon-plus\" aria-hidden=\"true\"><\/i><\/span><span class=\"fusion-toggle-heading\">6. Does DHW change how the heat pump works internally?<\/span><\/a><\/h4><\/div><div id=\"6cee403cca43a73dc\" class=\"panel-collapse collapse \" aria-labelledby=\"toggle_6cee403cca43a73dc\"><div class=\"panel-body toggle-content fusion-clearfix\">\n<p data-pm-slice=\"1 1 &#091;&#093;\">No. DHW changes the operating targets (temperatures and scheduling), but the thermodynamic heat pump process remains the same.<\/p>\n<\/div><\/div><\/div><\/div><\/div><script type=\"application\/ld+json\">\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@graph\": [\n    {\n      \"@type\": \"Article\",\n      \"@id\": \"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/#article\",\n      \"headline\": \"Domestic Hot Water (DHW) Integration in Heat Pump Systems\",\n      \"url\": \"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/\",\n      \"image\": \"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2026\/02\/domestic-hot-water-1200x655.webp\",\n      \"datePublished\": \"2026-02-10\",\n      \"author\": {\n        \"@type\": \"Organization\",\n        \"@id\": \"https:\/\/www.idm-energie.at\/en\/#organization\",\n        \"name\": \"iDM Energiesysteme GmbH\",\n        \"url\": \"https:\/\/www.idm-energie.at\/en\/\"\n      },\n      \"publisher\": {\n        \"@id\": \"https:\/\/www.idm-energie.at\/en\/#organization\",\n      \"logo\": {\n        \"@type\": \"ImageObject\",\n        \"url\": \"https:\/\/www.idm-energie.at\/wp-content\/uploads\/2020\/10\/logo_iDM-80.jpg\"\n      }\n\n      },\n      \"about\": {\n        \"@type\": \"Thing\",\n        \"name\": \"Domestic hot water \",\n        \"sameAs\": [\n          \"https:\/\/www.google.com\/search?kgmid=\/g\/1q6h_pv53\",\n          \"https:\/\/www.wikidata.org\/wiki\/Q3046670\"\n        ]\n      },\n      \"isPartOf\": {\n        \"@type\": \"WebPage\",\n        \"@id\": \"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/#webpage\",\n        \"name\": \"Heat Distribution & Hydronics\",\n        \"url\": \"https:\/\/www.idm-energie.at\/en\/heat-distribution\/\"\n      },\n      \"mentions\": [\n        {\n          \"@type\": \"Thing\",\n          \"name\": \"Legionella\",\n          \"sameAs\": \"https:\/\/www.wikidata.org\/wiki\/Q158013\"\n        }\n      ]\n    },\n    {\n      \"@type\": \"BreadcrumbList\",\n      \"@id\": \"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/#breadcrumb\",\n      \"itemListElement\": [\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 1,\n          \"name\": \"Heat Pump Technology\",\n          \"item\": \"https:\/\/www.idm-energie.at\/en\/heat-pump-technology\/\"\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 2,\n          \"name\": \"Heat Distribution\",\n          \"item\": \"https:\/\/www.idm-energie.at\/en\/heat-distribution\/\"\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 3,\n          \"name\": \"Domestic Hot Water\",\n          \"item\": \"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/\"\n        }\n      ]\n    },\n    {\n      \"@type\": \"FAQPage\",\n      \"@id\": \"https:\/\/www.idm-energie.at\/en\/heat-distribution\/domestic-hot-water\/#faq\",\n      \"name\": \"FAQ: Domestic Hot Water (DHW) & Heat Pumps\",\n      \"mainEntity\": [\n        {\n          \"@type\": \"Question\",\n          \"name\": \"What is domestic hot water (DHW) in a heat pump system?\",\n          \"acceptedAnswer\": {\n            \"@type\": \"Answer\",\n            \"text\": \"DHW is hot tap water for showers, baths, and sinks. 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