How to spot a quality ventilation system when you see it

Paul Williams of Domus Ventilation looks at why quality is more crucial than ever in specifying whole ventilation systems for domestic schemes, and how to identify it. 

The word ‘quality’ gets bandied about all over the place. Let’s face it, no sane company is going to say their products and services aren’t good quality. When it comes to ventilation, it’s no different: everyone seemingly makes good quality ventilation products and systems. But how do you define quality, and is it actually important? 


In the world of ventilation, quality really does matter. Using poor quality products will most likely result in a ventilation system that is unable to deliver the air flow required to comply with Building Regulations, and make for an uncomfortable environment in which to live. But that’s not all; it could also make for a noisy system and one that leaks condensation onto walls and ceilings, leading to the formation of mould which is not only unsightly but can be hazardous to health. 


With whole house ventilation systems featuring Mechanical Extract Ventilation (MEV) and Mechanical Ventilation with Heat Recovery (MVHR) as the main means of meeting the revised Part F Ventilation of Building Regulations, the quality of these units can make or break a system.

A good quality unit will have a low Specific Fan Power (SFP), which reduces energy consumption and directly impacts on a property’s Dwelling Emission Rate (DER). In the case of MVHRs, the heat exchanger is a key component so be sure to check its proficiency. The heat exchangers featured within our Domus HRXE range of MVHRs enable up to 95% of waste heat to be recovered, making it highly efficient.

Important features to look for in MVHR units are a thermal bypass which automatically activates when the air temperature reaches a pre-set level, allowing in cooler, fresh, filtered air without warming it through the heat exchanger; and integral humidity sensors which automatically changes the extract speed from background to boost as the level of humidity increases. The units must be listed on the SAP Product Characteristics Database (PCDB).

If MEV and MVHR units are seen as the heart of the ventilation system, they can only function efficiently if the arteries – the ducting – is of a similarly good standard. Unfortunately, this is where the majority of problems arise, as ducting quality is often forsaken on the grounds of price. If you want your mechanical ventilation system to function correctly, it’s imperative to invest in quality ducting that has been designed to work in harmony as part of a system and has been third party tested for end-to-end system performance. A good quality ducting system will have exacting tolerances and push fits together for minimal air and moisture loss and maximum system efficiency. It’s easy to spot poor quality ducting as the channel or pipe bows, or looks like it is concave, or the wall thickness appears uneven. 

And remember, never use flexible duct work in place of rigid ducting as it causes a lot more air resistance and can be crushed easily. 

A quality ducting system will also come with a range of useful accessories to help you meet site circumstances, such as ducting silencers, aerodynamic bends and pollutant filters. In addition, it should be accompanied by dedicated ducting insulation, and firestopping products. 


Of course, you can have the best ventilation products in the world, but if the system design is not up to scratch, then it won’t lead to the results you expect. So quality matters here too.

While some might think the ventilation unit should be the starting point, it’s actually the ducting drawing that needs to come first; before unit specification and before the other services (gas, water pipes etc) going in, as otherwise you will need to add more duct work to get around these obstacles. Doing ducting drawings is not easy, but ‘quality’ manufacturers will be able to provide these for you, so be sure to take advantage of this service.


Over the years we have seen just about all the mistakes that could be made onsite, from installers trying to simplify duct runs to save time and money; using flexible duct work at final connections or around obstructions such as steel beams; using the wrong size air bricks and incorrect size air valves; not using ducting insulation, and a whole lot more.

With the revised Building Regulations ‘Approved Document F, Volume 1: Dwellings’ (ADF1), which came into effect in 2022, the ventilation rate calculations have been considerably simplified and reporting has been tightened up to drive compliance and, ultimately, system quality. 

Quality does come at a cost and there will always be a balance between these two factors. But quality ventilation products are often designed with easy – and therefore quick – installation in mind. Opting for lower cost products may well end up being a false economy.

Paul Williams is product manager at Domus Ventilation