{"id":2815,"date":"2026-01-14T12:47:15","date_gmt":"2026-01-14T12:47:15","guid":{"rendered":"https:\/\/svetainiuperkelimas.eu\/vilprasauna\/?p=2815"},"modified":"2026-07-10T15:15:05","modified_gmt":"2026-07-10T12:15:05","slug":"tw25-triple-flue-overview-when-is-a-flue-needed-that-also-supplies-combustion-air","status":"publish","type":"post","link":"https:\/\/vilpraindustries.com\/en\/trisienio-dumtraukio-tw25-apzvalga-kada-reikalingas-dumtraukis-kuris-taip-pat-tiekia-degimo-ora\/","title":{"rendered":"Triple-wall TW25 review: when do you need a chimney that also supplies combustion air?"},"content":{"rendered":"<p class=\"wp-block-paragraph\">Modern homes are getting tighter (better insulation, fewer air leaks), and many appliances are designed to work <strong>independently of room air<\/strong>. That\u2019s where a <em>chimney that also brings combustion air <\/em>becomes a smart\u2014and sometimes necessary\u2014choice.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\u201eVilpra Chimneys TW25\u201c<\/strong> is <strong>a triple-wall air-flue chimney system<\/strong>designed to:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Supply combustion air<\/strong> to <strong>a room-sealed heating appliance<\/strong> and<\/li>\n\n\n\n<li><strong>Convey combustion products<\/strong> safely to the atmosphere, using <strong>natural draught<\/strong>.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The following information explains when <a href=\"https:\/\/vilpraindustries.com\/en\/product-cat\/triple-wall-chimneys-tw25\/\" data-type=\"product_cat\" data-id=\"41\">TW25<\/a> is <strong>the right choice<\/strong>, what it\u2019s built for, and how to decide.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"ka-is-tikruju-reiskia-uzdara-patalpa\">What does \u201croom-sealed\u201d actually mean?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Room-sealed<\/strong> (also called \u201croom air independent\u201d) appliance is built so it <strong>doesn\u2019t take combustion air from the room<\/strong>it\u2019s installed in. Instead, it needs a dedicated air supply route. TW25 provides that air supply while also taking exhaust out through the same chimney system.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This approach helps:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Maintain stable combustion in airtight buildings<\/li>\n\n\n\n<li>Reduce risk of indoor air pressure issues affecting draft<\/li>\n\n\n\n<li>Keep indoor air quality more consistent (no \u201cusing up\u201d room oxygen)<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"kas-yra-tw25-sistema\">What is the TW25 system?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><a href=\"https:\/\/vilpraindustries.com\/en\/product-cat\/triple-wall-chimneys-tw25\/\" data-type=\"product_cat\" data-id=\"41\">TW25<\/a><\/strong> is a <strong>triple-wall chimney<\/strong>intended for <strong>gas, oil<\/strong> or <strong>solid-fuel appliances<\/strong>that are room-sealed and operate on <strong>natural draught (N1)<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Key TW25 characteristics from the catalogue:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Working temperature:<\/strong> up to <strong>450 \u00b0C<\/strong><\/li>\n\n\n\n<li><strong>Pressure class:<\/strong> <strong>N1 \u2013 natural draught<\/strong><\/li>\n\n\n\n<li><strong>Condensate resistance: W \u2013 designed for wet operating conditions<\/strong><\/li>\n\n\n\n<li><strong>Sootfire resistance: G \u2013 resistant<\/strong><\/li>\n\n\n\n<li><strong>Insulation:<\/strong> injected mineral wool, <strong>25 mm<\/strong><\/li>\n\n\n\n<li><strong>Install location:<\/strong> can be used <strong>inside or outside<\/strong><\/li>\n\n\n\n<li><strong>Product designation code:<\/strong> <strong>EN 1856-1 T450-N1-W-V2-L50xxx-G80<\/strong><\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"572\" src=\"https:\/\/vilpraindustries.com\/wp-content\/uploads\/2026\/01\/Triple-wall-TW25-explained-when-do-you-need-a-chimney-that-also-supplies-combustion-air-1-1-1-1024x572.png\" alt=\"\" class=\"wp-image-2826\" srcset=\"https:\/\/vilpraindustries.com\/wp-content\/uploads\/2026\/01\/Triple-wall-TW25-explained-when-do-you-need-a-chimney-that-also-supplies-combustion-air-1-1-1-1024x572.png 1024w, https:\/\/vilpraindustries.com\/wp-content\/uploads\/2026\/01\/Triple-wall-TW25-explained-when-do-you-need-a-chimney-that-also-supplies-combustion-air-1-1-1-300x167.png 300w, https:\/\/vilpraindustries.com\/wp-content\/uploads\/2026\/01\/Triple-wall-TW25-explained-when-do-you-need-a-chimney-that-also-supplies-combustion-air-1-1-1-768x429.png 768w, https:\/\/vilpraindustries.com\/wp-content\/uploads\/2026\/01\/Triple-wall-TW25-explained-when-do-you-need-a-chimney-that-also-supplies-combustion-air-1-1-1-18x10.png 18w, https:\/\/vilpraindustries.com\/wp-content\/uploads\/2026\/01\/Triple-wall-TW25-explained-when-do-you-need-a-chimney-that-also-supplies-combustion-air-1-1-1-900x502.png 900w, https:\/\/vilpraindustries.com\/wp-content\/uploads\/2026\/01\/Triple-wall-TW25-explained-when-do-you-need-a-chimney-that-also-supplies-combustion-air-1-1-1.png 1376w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"kada-reikalingas-dumtraukis-tiekiantis-degimo-ora\">When do you need a chimney that supplies combustion air?<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"1-jusu-prietaisas-yra-aiskiai-nurodytas-kaip-uzdaros-patalpos-tipo\">1) Your appliance is explicitly \u201croom-sealed\u201d<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">If the appliance manual states it must be installed as <strong>room-sealed \/ room air independent<\/strong>it needs a reliable combustion air supply that does not depend on room ventilation. TW25 is designed for exactly that use-case.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"2-your-building-is-very-airtight-1\">2) Your building is very airtight<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">In newer or renovated homes, natural infiltration is low. A traditional setup that steals air from the room can lead to:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>unstable burning,<\/li>\n\n\n\n<li>draft problems,<\/li>\n\n\n\n<li>or negative-pressure situations when extractor fans run.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">A system like TW25 helps by providing a dedicated air pathway for combustion.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"3-norite-kad-montavimo-trasa-butu-tvarkingesne-ir-lengviau-numatoma-viduje-arba-lauke\">3) You want a cleaner, more predictable installation route (inside or outside)<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Because TW25 is designed for <strong>internal or external use<\/strong>, it\u2019s often chosen when the appliance is in a location where routing separate ducts would be awkward.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"4-naudojate-kuro-rusis-kurioms-svarbus-atsparumas-suodziu-uzsidegimui\">4) You\u2019re using fuels where sootfire resistance matters<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/vilpraindustries.com\/en\/product-cat\/triple-wall-chimneys-tw25\/\" data-type=\"product_cat\" data-id=\"41\">TW25<\/a> is classified as <strong>G \u2013 resistant<\/strong> (sootfire resistant), which is particularly relevant for <strong>solid fuels<\/strong>.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"kada-tw25-gali-buti-netinkamas-pasirinkimas\">When TW25 may not be the right choice?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">TW25 is a <strong>natural draught (N1) system<\/strong>. If your appliance requires a <strong>positive pressure (fan-assisted)<\/strong> air-flue system, you\u2019re typically looking at a different category (for example, Vilpra\u2019s <strong>CLV<\/strong> is classified as <strong>P1 \u2013 positive pressure<\/strong> and is also meant to supply combustion air to room-sealed heating appliances).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Also, <strong>for room-sealed gas fireplaces<\/strong> Vilpra lists a dedicated <strong>CGF<\/strong> concentric air-flue system for that application.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><em>(In short: match the chimney type to the appliance\u2019s required pressure class and application.)<\/em><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"saugos-pastaba-atstumas-iki-degiu-medziagu\">Safety note: distance to combustible materials<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The TW25 catalogue lists <strong>distance to combustible material \u2265 80 mm<\/strong> (tested non-enclosed and with insulated floor penetration).<br>But it also clearly notes that the actual minimum distance must follow:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>the chimney<strong> marking\/designation<\/strong> and<\/li>\n\n\n\n<li><strong>national legal acts<\/strong> \u2013 and if they differ, you must follow the <strong>bigger distance<\/strong>.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"greito-sprendimo-kontrolinis-sarasas-ar-tw25-tinka-jums\">Quick decision checklist: is TW25 for you?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">TW25 is a strong candidate if:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The appliance is <strong>room-sealed \/ air independent<\/strong><\/li>\n\n\n\n<li>The appliance uses <strong>natural draught (N1)<\/strong><\/li>\n\n\n\n<li>You want a system usable <strong>inside or outside<\/strong><\/li>\n\n\n\n<li>You need resistance to <strong>wet-condition (W)<\/strong> (condensate-resistant design)<\/li>\n\n\n\n<li>You\u2019re installing for <strong>gas, oil, or solid fuels<\/strong> and value <strong>G sootfire resistance<\/strong><\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">If any of those are unclear, the catalogue\u2019s guidance is simple: system suitability should be decided by considering the <strong>appliance manufacturer documentation<\/strong>, <strong>chimney installation guide<\/strong> and <strong>national legal acts<\/strong>.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"dazniausiai-uzduodami-klausimai\">Frequently Asked Questions<\/h2>\n\n\n<div id=\"rank-math-faq\" class=\"rank-math-block\">\n<div class=\"rank-math-list\">\n<div id=\"faq-question-1768395099966\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question\"><strong>Can TW25 be installed outside the building?<\/strong><br><\/h3>\n<div class=\"rank-math-answer\">\n\n<p>Yes \u2014 TW25 can be used internally or externally.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1768395121452\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question\"><strong>What types of fuel-powered devices does the TW25 support?<\/strong><\/h3>\n<div class=\"rank-math-answer\">\n\n<p>Gas, oil, or solid fuel systems.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1768395152860\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question\"><strong>Is TW25 sootfire resistant?<\/strong><\/h3>\n<div class=\"rank-math-answer\">\n\n<p>Yes \u2014 classified as<strong> G (resistant)<\/strong>.<\/p>\n\n<\/div>\n<\/div>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>\u0160iuolaikiniai namai tampa vis sandaresni (geresn\u0117 izoliacija, ma\u017eiau oro nuot\u0117ki\u0173), o daugelis prietais\u0173 suprojektuoti taip, kad veikt\u0173 nepriklausomai nuo patalpos oro. B\u016btent tod\u0117l d\u016bmtraukis, kuris taip pat tiekia degimo or\u0105, tampa protingu \u2013 o kartais ir b\u016btinu \u2013 pasirinkimu. \u201eVilpra Chimneys TW25\u201c yra trisien\u0117 oro-d\u016bm\u0173 d\u016bmtraukio sistema, sukurta: Toliau pateikiama informacija, kada TW25 yra tinkamas [&hellip;]<\/p>\n","protected":false},"author":5,"featured_media":2826,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_gspb_post_css":"","_yoast_wpseo_title":"","_yoast_wpseo_metadesc":"","_yoast_wpseo_focuskw":"","rank_math_title":"","rank_math_description":"","rank_math_focus_keyword":"","footnotes":""},"categories":[39],"tags":[],"class_list":["post-2815","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-dumtraukiu-sistemos"],"acf":[],"_links":{"self":[{"href":"https:\/\/vilpraindustries.com\/en\/wp-json\/wp\/v2\/posts\/2815","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vilpraindustries.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/vilpraindustries.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/vilpraindustries.com\/en\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/vilpraindustries.com\/en\/wp-json\/wp\/v2\/comments?post=2815"}],"version-history":[{"count":1,"href":"https:\/\/vilpraindustries.com\/en\/wp-json\/wp\/v2\/posts\/2815\/revisions"}],"predecessor-version":[{"id":4598,"href":"https:\/\/vilpraindustries.com\/en\/wp-json\/wp\/v2\/posts\/2815\/revisions\/4598"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/vilpraindustries.com\/en\/wp-json\/wp\/v2\/media\/2826"}],"wp:attachment":[{"href":"https:\/\/vilpraindustries.com\/en\/wp-json\/wp\/v2\/media?parent=2815"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vilpraindustries.com\/en\/wp-json\/wp\/v2\/categories?post=2815"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vilpraindustries.com\/en\/wp-json\/wp\/v2\/tags?post=2815"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}