{"id":6573,"date":"2025-09-28T12:00:00","date_gmt":"2025-09-28T11:00:00","guid":{"rendered":"https:\/\/www.marshflattsfarm.org.uk\/wordpress\/?p=6573"},"modified":"2025-09-29T07:30:28","modified_gmt":"2025-09-29T06:30:28","slug":"above-ceiling-mvhr-ductwork","status":"publish","type":"post","link":"https:\/\/www.marshflattsfarm.org.uk\/wordpress\/?p=6573","title":{"rendered":"Above-Ceiling MVHR Ductwork"},"content":{"rendered":"\n

The supplier of the MVHR equipment (BPC Ventilation<\/a>) prepared a design showing the rough locations of the inlet and extract vents, specifying that each vent should have two 75mm semi-rigid ducts attached (in order to achieve the required airflow – especially given the relatively long duct runs). The detail of the duct routing is left to the discretion of the installer. I settled on locating the vents along the centreline of the workshop then running the ducts on the East side – mostly because the access hatches are just to the West side of the central bracing planks, which form a natural walkway – at least for now, before the rest of the loft insulation gets installed. While the 75mm duct (FR\u00c4NKISCHE profi-air classic grey NW75) specifies a minimum bend radius of only 150mm there is no harm in having much larger radius bends where space allows.<\/p>\n\n\n\n

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Some of the MVHR ductwork above the ceiling in the Workshop. The black plastic moulding is a plenum chamber that feeds the air vent (that will be) fitted below the ceiling.<\/figcaption><\/figure>\n\n\n\n

The loft space will be ‘cold’ (deliberately ventilated to the outside) and I initially looked at pre-insulated ductwork but was advised that’s not as good as it might be and the best approach is to install un<\/em>insulated ductwork ‘in the middle’ of the loft insulation. The insulation visible in the above photo is a 100mm-thick layer between the ceiling joists and that – together with the grey ducts – will get covered by the additional 170mm of insulation installed on top.<\/p>\n\n\n\n

At their other ends, the ducts connect to another plenum chamber adjacent to the MVHR unit.<\/p>\n\n\n\n

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The ‘inlet’ plenum chamber feeding the three inlet vents (which each have two 75mm semi-rigid duct connections). The inlet from the MVHR unit is underneath.<\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"

The supplier of the MVHR equipment (BPC Ventilation) prepared a design showing the rough locations of the inlet and extract vents, specifying that each vent should have two 75mm semi-rigid ducts attached (in order to achieve the required airflow – … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[94,58,60],"tags":[],"class_list":["post-6573","post","type-post","status-publish","format-standard","hentry","category-outbuildings","category-ventilation","category-ventilation-ducts"],"_links":{"self":[{"href":"https:\/\/www.marshflattsfarm.org.uk\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/6573","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.marshflattsfarm.org.uk\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.marshflattsfarm.org.uk\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.marshflattsfarm.org.uk\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.marshflattsfarm.org.uk\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=6573"}],"version-history":[{"count":3,"href":"https:\/\/www.marshflattsfarm.org.uk\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/6573\/revisions"}],"predecessor-version":[{"id":6581,"href":"https:\/\/www.marshflattsfarm.org.uk\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/6573\/revisions\/6581"}],"wp:attachment":[{"href":"https:\/\/www.marshflattsfarm.org.uk\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6573"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.marshflattsfarm.org.uk\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6573"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.marshflattsfarm.org.uk\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6573"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}