Don Spearman, managing director at Xpelair, looks at the growth of central extract ventilation systems and suggests ways to help installers fit the right system for the right application.
With buildings becoming more airtight, it is crucial that ventilation systems are specified and installed correctly to deliver the required performance levels, help reduce carbon emissions and comply with industry regulations.

However, because many installers have not undertaken the necessary training, the majority of the ventilation systems are either not fit for purpose or are being installed incorrectly.

Ultimately, poor ventilation is a serious issue. Not only can excessive condensation cause mould growth, leading to cosmetic and structural damage to the fabric of a dwelling, but mould and other pollutants can create extremely poor indoor air quality which, for some homeowners or tenants, can lead to health issues.

There are a number of ventilation systems for installers to choose from: from intermittent and passive stack to MEV and MVHR. However, in the commercial sector, the move towards low energy ventilation means the days of the AC motor are limited.

These traditional intermittent systems are a shrinking part of the market because they lack aesthetic appeal and have maintenance issues. This has led to the rise of central extract systems, which are more energy efficient, quieter and can be catered to specific projects on design or convenience.





The growth of these central extract systems has resulted in a number of installation issues. The most common is the use of flexible ducting and how it can create unacceptable bends that can restrict airflow and increase system pressure. In addition, using flexible ducting for an entire installation means it can be easily crushed in the roof space, diminishing system performance over time and potentially leading to collapse.

To combat this, it is crucial to use rigid ducting for the majority of the duct route and only use flexible ducting when absolutely necessary. This, combined with planning the duct route carefully to avoid unnecessary bends and ensuring ducts take the path of least resistance, will maintain system efficiency and achieve better results. It is also essential mechanically to fix and tape joints on the ducting to ensure an airtight seal.

How ducts connect

Another important factor to consider is how the ducts connect. Don't cram flexible ducting into a small space, for example, or snake it unnecessarily as it will reduce the air flow. Fixing and sealing the ducts securely will also ensure that the system performs according to spec. It is crucial not to rush connections or fabricate components not suitable for the transfer of air to prevent and minimise leakage.

To ensure the required performance and indoor air quality is achieved, it is imperative that the filters are regularly inspected and maintained. Alarmingly, a recent BRE report stated that there is no replacement market for filters, meaning that even basic maintenance on systems is not being undertaken. If filters wear out because they have been left too long and not replaced, it will lead to a build up of humidity, carbon dioxide and other pollutants, and drive up energy use.

To help achieve the highest standards of installation, Xpelair runs dedicated training for commercial, industrial and domestic ventilation that covers ventilation strategies, how different systems work, planning and design and installation and commissioning guidance.

To complement this and add value to its service, the company has also launched a design service to ensure installers have everything at their disposal for best practice. By recreating dwellings in a 3D format, Xpelair's software calculates all resistances and selects the right products to suit, determining the best locations for the system and its ducting in accordance with the building regulations. By being proactive and eliminating the potential issues before installing, it ensures no time, labour and product costs are wasted.

Looking forward, we believe the most logical move to ensure the highest installation standards would be to introduce a competent persons scheme or approved installer scheme for the industry. Similar to the Gas Safe scheme, this would ensure everyone dealing with ventilation systems was trained and competent.

Not only would this help raise the bar within the industry but it would also help further improve the image and reputation of the industry with our customers, for manufacturers and installers alike.