Air network

With the move to more energy efficient, airtight homes, partly driven by what was known as the Code for Sustainable Homes and by changes to Building Regulations, ventilation has evolved into a whole house solution, with mechanically driven systems such as Mechanical Extract Ventilation (MEV) and Mechanical Ventilation with Heat Recovery (MVHR).

This, in turn, has driven considerable improvements to the individual ventilation system components. Ducting is no longer just plastic tubing pushed together. If the mechanical ventilation units are to perform efficiently, ducting needs to be an airtight, end to end system. High quality ducting, such Polypipe’s range of Domus ducting, is therefore essential in helping to ensure effective and efficient ventilation performance.

The quality of a ducting system is not the only change brought about by the increasing popularity of mechanical ventilation systems. The choice of ducting and accessories has never been greater, giving designers, installers and developers maximum flexibility in system preference and installation methods. However, the familiarity of the rigid duct system with flat and round profiles remains unchanged. Flat channel duct is effective and space saving, whilst the round profiles offer improved flow rates and smoother air flow.

Rigid ducting is fitted in a traditional branch design, with ducting to rooms ‘branching’ off a main trunk duct connected to a whole house ventilation unit or fan.

New challenger
A more recent newcomer to the UK market is the semi-rigid Radial ducting system. More commonly used across mainland Europe, these systems have really begun to take off in the UK as they provide a very easy ducting solution for whole house mechanical ventilation systems. The ducting, typically Ø75 mm, is flexible enough to go round bends, but rigid enough to retain its shape. With a Radial system, each room terminal is served by its own duct run which connects directly to a central distribution system. As you can imagine, this makes for a considerably quicker and easier installation than traditional branch ducting and with far fewer parts.

Such systems can also benefit from reduced air leakage and improved air flow, which makes for easier commissioning and a quieter system as the air flow is smooth and cross-talk noise is minimal. Having a dedicated duct run to each room means that individual rooms can be commissioned to extract or supply air at exact rates without it impacting on other rooms – much easier all round.

Additional elements
Whether you specify or install Radial or traditional rigid branch ducting, do ensure the ducting system you pick has all the accessories you need. A ‘mix and match’ approach is not suitable for ducting, so it is important to check the manufacturer is able to supply all of the accessories that you need to create the ventilation system as a whole.

Ducting insulation should also be on your list of requirements, as under Building Regulations it’s an essential component. If you are using the ducting as part of a mechanical ventilation system, regulations stipulate that ducting must be insulated where it passes through unheated areas and voids, such as loft spaces, to reduce the possibility of condensation forming. A minimum duct insulation standard, which is the equivalent of at least 25 mm of a material having a thermal conductivity of ≤0.04 W/m.K, is required. A number of insulating materials are not able to meet this requirement, so it’s important you opt for a system designed specifically to meet the regulations.

Domus Thermal has been recognised by the LABC for this purpose, as well as for insulating rigid ducting passing between the MVHR (Mechanical Ventilation with Heat Recovery) appliance and external terminals in the heated area of a property. The latest NHBC guidelines reinforce this usage, stressing the need to prevent condensate forming on the outside of these colder duct runs.

Having a wide range of accessories allows for a variety of solutions to individual problems. It gives you the ability to specify the ducting system in the most economic and energy efficient manner if, for whatever reason, you cannot meet the designed layout due to unforeseen site circumstances.

Domestic ventilation has changed significantly over the past decade. New domestic properties now often come with house wide ventilation systems that require a quality ducting system that has been tested for end to end performance, rather than just duct runs. Ducting has become specifiable. That’s why getting the right ducting system is vital, and is an essential element of ventilation design and installation.