Flexible Ducting Hoses for domestic and light commercial use
Flexible ducting is made from PVC, aluminium, vinyl or PU (polyurethane), and comes in: Acoustic, reinforced, combi, semi-rigid, insulated and vinyl varieties. It is used when space constrictions make rigid duct impractical. It comes in: Acoustic, reinforced, combi, semi-rigid, insulated and vinyl v...
Flexible ducting is made from PVC, aluminium, vinyl or PU (polyurethane), and comes in: Acoustic, reinforced, combi, semi-rigid, insulated and vinyl varieties.It is used when space constrictions make rigid duct impractical. It comes in: Acoustic, reinforced, combi, semi-rigid, insulated and vinyl varieties.
i-sells provides round and rectangular flexible ducting in both PVC and combi hose variations. Rectangular or “flat” ducting can be easier to install and to conceal but suffers from higher resistance than round flexible hose. We would always recommend the use of round ducting over rectangular or flat for this reason, however, for installation or cosmetic purposes, we understand that this is not always viable.
Flexible duct can be used as a very quick way of setting up simple duct runs for air conditioning units, bathroom and kitchen extractor fans, cooker hoods, dust extraction and for general HVAC systems in both commercial and industrial settings.
Typical uses for flexible ducting over rigid plastic duct would be when ducting around corners or within eaves or soffits, and small or tight spaces that make working with rigid ducting difficult or impossible.
It is not recommended for applications where very high heat is involved, such as venting furnaces. In this circumstance, a flue system is a far more appropriate option.
Sizes range from 50mm to 600mm diameter in various materials, with our most popular sizes being 50mm, 100m, 120mm, 125mm, 150mm and 200mm diameter (4-inch, 5-inch, 6-inch and 8-inch). These tend to be used more within a domestic application, but larger sizes are available or can be fabricated for larger commercial purposes.
Coping with pressure loss
Pressure loss can be common due to the internal resistance being higher than rigid duct, this is as a result of both the ridges within the structure of the ducting and the material itself having greater air resistance than rigid duct which tends to have a smoother internal surface.
Pressure loss can also be influenced by the way the ducting was installed. If secured without being fully stretched, the surface area of the duct is increased, adding additional resistance to the run and lowering the pressure within it.
This effect can be minimised by ensuring that when you install flexible ducting yourself, the pipe is pulled as tightly as possible, with little to no additional pressure or sagging to the pipe throughout the run. This means it must be supported correctly, without anything pressing against it.
All our plastic flexible ducting contains an internal wire helix to prevent any natural sagging and to keep the internal diameter of the pipe as wide as possible. Our semi-rigid ducting does not require any additional re-enforcement to maintain its shape.
Installation of PVC Flexible Ducting
To maximise the efficiency of your flexible duct run, please follow the simple installation tips below.
To cut PVC, insulated aluminium, or even vinyl ducting, you will only need a sharp knife such as a utility knife or (box cutter) and a pair of wire cutters or snips. Put a mark on your ducting at the desired cutting point, then use the blade to carefully cut the material. In the case of insulated ducting, you will have several centimetres of insulation to cut through before you get to the actual hose itself.
Once the cut has been completed, you will need to use the snips or wire cutters to cut through the metal wire helix inside. We recommend the use of safety gloves during this process, as cutting the hose and then dealing with sharp wires could be dangerous.
Once your ducting is cut to the desired length, you would place it over (for example) a spigot, then use a quick release worm drive clip or standard hose clip to tighten the flexible duct around it. If you do not have a worm drive clip, you can use duct tape, however, duct tape loses its adhesive qualities over time and may lead to pressure loss, or complete failure of the duct run.
Installing Semi-Rigid Flexible Ducting
To cut semi-rigid ducting, you will first need to mark out your area to cut, using either masking tape or a marker. Then use a box cutter or utility knife to carefully cut a small pilot hole. Once you have made your pilot hole, you can use a pair of snips to cut the pipe to your desired length.
As semi-rigid ducting isn’t as pliable as a plastic flexible hose, you may find it easier to install around a vent pipe or spigot if you snip three half-inch to one-inch cuts on the inside of the pipe. This will make it easier to press onto another pipe. You can then place a quick release worm drive clamp around the duct and the connecting part, and tighten, creating a tight seal.
Hanging a flexible duct run
Hanging flexible ducting is possible with the use of “webbing”, as it allows the duct to hang naturally with minimal pressure being placed on the pipe. The webbing acts as a support and can be easily attached to roof joists. Ensure that adequate support is given, so that no sagging occurs, as this would increase resistance within the duct run and could cause additional wear and tear of the fan it is attached to. It is also important to make sure that the flex duct is sitting at least 2-3 inches off the bottom of the floor.
Flexible Ducting Kits
To make installing flexible ducting a little easier, i-sells provides warm air exhaust kits, soffit venting kits, cooker hood kits and tumble dryer kits in 100mm and 125mm diameter, specifically put together to ensure you have anything you need to easily install your duct run.
Flexible Duct vs Rigid Ducting
Less internal resistance – Superior airflow
Easy to install in cramped conditions
Easier to create an airtight seal
Generally cheaper to purchase and install
Less chance of liquid water “pooling”
Less pressure loss
Far more durable, less chance of damage
Types of Flexible Ducting Hose
White PVC Flexible Hose
White, lightweight, PCV (Polyvinyl chloride) hose is perfectly suited for light domestic use such as venting extractor fans, cooker hoods and tumble dryers. An internal metal wire helix helps retain its shape. i-sells provides PVC flexible hose in 80mm, 100mm, 125mm and 150mm diameter, with 3m to 45m lengths, in both round and rectangular (flat) varieties. Manufactured from flame retardant PVC film, max Working Temperature: -5°c to 70°c.
Aluminium Flexible Hose
Light and very flexible hose reinforced with a 5-layer laminate of aluminium/polyester. It is a versatile product which can be used for low and medium pressure heating, ventilation, cooling, and exhaust systems. Perfect for ducting your Bathroom or Kitchen extractor fan, Hydroponics, In-Line Extract Fans, Tumble Dryer, or Cooker Hood. This flexible hose can be used as a part of a long ductwork run for a variety of purposes including whole-house ventilation, passive stack vent, air conditioning, positive pressure ventilators, HVAC, and Heat Recovery Systems.
Max/min Temperature: +150c / -30c, maximum operating pressure: 2500 pa maximum air velocity: 30m/sec.
Insulated Aluminium Hose
Insulated flexible duct features all the benefits of standard flexible aluminium duct, including the 5 layer laminate inner lining, but with the addition of 25mm in glass wire wool insulation. This makes it ideal for ducting through cold areas such as loft voids where condensation build-up is a concern.
Max / Min Temperature: +150c / -30c, maximum operating pressure: 3000 Pa, maximum air velocity: 30m/sec.
Acoustic Flexible Ducting
Much the same as a standard aluminium flexible hose, but featuring an internal layer of acoustically transparent interliner. This interliner reduces sound travelling along the duct run and from the connected ventilation system, whilst shielding the airstream for any fibreglass insulation, making fibre migration into the airflow highly unlikely. Fire-resistant certified acoustic performance and Suitable for medium and low-pressure applications.
Semi-Rigid Aluminium Flexible Ducting
Semi-rigid hoses are flexible and can be bent into shape by hand, and are perfect for runs that require a firm and yet flexible hose. Bend and crush resistant, high temperatures tolerance, for exhaust and gas extraction purposes.
Maximum air velocity of 30m/s and 2500 Pa working pressure. High-tensile strength with limited noise attenuation.
Polyester Reinforced PVC Hose
Highly resilient and corrosion-resistant PVC flexible hose designed to be used for low and medium pressure heating, ventilation, cooling, and exhaust systems. Fire-Retardant PVC and high tensile steel wire.
Max / Min Temperature: +80c / -30c. Nominal Thickness of Inner Duct: 250 microns. Max. Operating Pressure: 3000 Pa. Max. Air Velocity: 30 m/s.
PVC Combi Hose
Aluminium and polyester hose with a PVC outer layer used as a substitute for insulated hose in various applications. Features an Inner Duct Construction of 1xAluminium, 1xPolyester and 1xPVC layers.
Temperature range: -30°C / +120°C, air velocity: 30m/s (max), nominal thickness of Inner duct: 106 microns. Available in both round and rectangular/flat varieties.
Uninsulated Vinyl Flexible Ducting
Highly flexible fabric ducting manufactured from a tough, puncture-resistant, grey coloured PVC coated woven glass cloth fabric supported by an encapsulated high tensile steel wire helix. Suitable for applications where high strength and flexibility is required. The wire helix contained within an additional internal layer, allows for a smooth internal surface, resulting in 10-25% air resistance.
PU Dust Extraction
Dust extraction hose is used in the transfer of materials such as dust, wood chippings and general lightweight industrial debris. Under low pressure, the hose can also vent exhaust gasses and fumes. Highly abrasive and puncture-resistant, PU dust extraction hose retains its flexibility and features an encapsulated high tensile steel helix, resulting in a smooth internal surface with minimal air resistance.
i-sells Flexible Ducting
i-sells provides Flexible ducting for purchase all around the UK. Custom sizes can be fabricated, and orders of stocked products over £100 are free of delivery charges.