Flexible ducting for residential and light commercial ventilation — connecting fans, MVHR units, and extract terminals to rigid duct runs where a straight rigid connection isn't practical.
This collection covers the Verplas flexible and semi-rigid hose range in diameters from 100mm to 250mm, spanning four distinct product types suited to different installation conditions. Choosing the right type matters: material, wall construction, and temperature rating each affect long-term performance, condensation risk, and noise levels in ways that a single generic "flex hose" won't address across all applications.
PVC flexible hose
The standard round PVC flexible hose — available in 100mm in lengths of 1m, 3m, 6m, and 15m — is the go-to short-section connector for bathroom and kitchen extract fans, connecting the fan spigot to the rigid duct run or external wall termination. It compresses and extends to navigate tight ceiling voids and wall penetrations, and accepts standard push-fit fittings from the Verplas round ducting range. This is an uninsulated product; runs through cold spaces should be kept as short as possible to limit condensation risk.
Heavy duty PVC-coated polyester fibre hose
The heavy duty range is manufactured from PVC-coated polyester fibre rather than plain PVC, giving it significantly greater crush resistance and a wider operating temperature range of -30°C to +80°C. Available in diameters from 100mm to 250mm in 6m boxes, it is the correct choice where the hose is subject to compression, foot traffic risk in loft installations, or where higher temperature tolerance is needed — for example, in proximity to plant or in commercial extract applications. The wider size range (up to 250mm) also makes it appropriate for higher-flow MEV branch connections that standard PVC hose cannot accommodate.
Semi-rigid aluminium hose
Available in 100mm, 125mm, and 150mm in 3m boxes, semi-rigid aluminium hose holds its shape once bent rather than springing back, which makes it preferable to plain PVC flex where the connection needs to stay routed around an obstruction without being clipped or supported. The aluminium construction also provides better resistance to rodent damage in accessible loft spaces. It connects directly to standard round PVC fittings and fan spigots using duct clamps.
Acoustic insulated flexible aluminium hose
The acoustic range adds a layer of mineral wool insulation wrapped around the aluminium inner and covered by an outer jacket, available in 100mm, 125mm, and 150mm in 10m lengths. The insulation serves two purposes simultaneously: it reduces heat loss through the duct wall in cold zones — reducing condensation risk on the duct exterior — and attenuates airborne noise transmitted through the duct from the fan or MVHR unit. This is the appropriate specification for MVHR branch connections to supply and extract valves in habitable rooms, and anywhere noise from continuous-running fans is a design concern. It should not be confused with the rigid Verplas Self-Seal Thermal range, which is a separate product for higher-flow trunk runs requiring a greater R-value.
Specifying correctly
Flexible ducting of any type creates more resistance per metre than rigid duct of the same diameter. Best practice is to use flex only for the final connection — typically no more than 1.5m — and to avoid tight bends that further increase pressure drop. Where a duct run requires a change of direction, a rigid bend in the hard duct run performs better than an equivalent bend formed in flexible hose. Always check the fan or MVHR manufacturer's maximum permissible system resistance before specifying long flex sections, particularly in acoustic insulated hose where the corrugated inner adds measurable resistance compared to smooth-bore rigid duct.
