Paul Williams, Domus Ventilation Product Manager, looks at ventilation ducting in new builds and why it’s often overlooked and undervalued.

Ducting can make or break a ventilation system, whether it’s a sophisticated Mechanical Ventilation with Heat Recovery (MVHR) system in a large house or a simple bathroom fan in an apartment. That’s because the ducting conveys the all-important fresh air to (and from, in the case of MVHR) the ventilation unit and into the property. If the air flow is impeded in the duct run, insufficient air reaches the fan in a timely way, and the property does not receive adequate ventilation. Maintaining air flow at a set level is especially important in whole house ventilation systems as otherwise the systems will not perform to their best ability.

Choose ducting wisely

I’d like to think that developers and HVAC contractors invest time into researching whole house ventilation systems and, hopefully, into their choice of extract fans. But has similar time and effort been spent into researching ducting? Quite possibly not. As I have stated above, ducting is at the heart of a successful ventilation system, so it is important to take the time to ensure you choose duct systems wisely. There is no set standard for ducting, but poor quality ducting is relatively easy to spot. If the ducting bows or looks like it’s concave, or the wall thickness appears uneven, it will not provide a tight fit when connected, leading to air and even condensation leakage. Good quality ducting will have exacting tolerances and connects together for minimal air and moisture loss and maximum system efficiency.

Make sure the ducting has been designed to work in harmony as part of a system and has been third party tested for end-to-end system performance. For MVHR and MEV systems, quality rigid ducting in larger sizes should be used. But whatever you do, and whatever size the ventilation system, avoid using flexible duct work in place of rigid ducting at all times, as it causes a lot more air resistance and can be crushed easily.

Drawing duct schemes require skill

Many people misjudge the level of skill required to produce ducting drawings. The duct runs, the number of bends and the angle of those bends, plus the temperature of the areas the ducting runs through, all affect the air flow. It’s important to keep ductwork runs as short and straight as possible, and minimise the number of bends.

This can best be achieved if the drawing is produced before the ventilation unit is specified and before services, such as gas and water pipes, go in. Make full reference to dwelling and room ventilation rates within the drawing.

By far the easiest option though is to outsource the drawing. Most manufacturers, Domus Ventilation included, will provide a system drawing free of charge, along with duct take-offs and estimations.

Lastly, be prepared! Site related constraints may change, and the duct drawing may need to alter. If changes have to be made, the air flow rates need to be re calculated and, where necessary, product changes accordingly. For example, if you must include a bend where one didn’t exist before, consider using something like a Domus Greenline Bend which has been cleverly engineered to reduce duct bend resistance by up to 60%. Stick to the plan when it comes to installation

Once the duct drawing is finalised and the ducting is ready to be installed, be sure contractors stick to it on site. It has been known for some to try save time by making the duct runs simpler or swapping rigid ducting for flexible ducting at final connections or around obstructions.

Ensure ducting insulation and fire-stopping products are fitted, as laid out in Building Regulations. Insulation is required where the ducting passes through unheated areas and voids, such as loft spaces. Fire-stopping products are necessary whenever a hole is made in a compartment wall for plastic ventilation ducting to pass through. In addition, non-combustible air bricks, such as Domus Ventilation’s Solis Air Brick, must be used where ductwork penetrates through the external cavity when above 18m in England and 11m in Scotland.

Take care of your ducting and it will take care of you Getting the ducting right really is one of the most important aspects of a residential ventilation system, yet it’s frequently the most overlooked and undervalued. By taking the time to consider ducting products, where they go and how they are installed, you are more than halfway to ensuring a good ventilation system that is Building Regulations compliant.

For more information, visit www.rdr.link/dbe023

The post Why ventilation ducting is overlooked and undervalued appeared first on PHPD Online.

Paul Williams, Domus Ventilation Product Manager explains why housebuilders and architects should be specifying MVHR systems in their new builds.

Valued at $106.69 million in 2022, the Mechanical Ventilation Heat Recovery (MVHR) UK market is predicted to reach $235.34 million by 2030. This extraordinary growth is being driven by increased awareness about the benefits of MVHR, as well as the adoption of these systems to comply with the latest uplift to Building Regulations.

MVHR systems take a whole house approach to ventilation, combing supply and extract ventilation in one system. They extract the stale air from wet rooms (kitchens, bathrooms, utility spaces) within a property via ducting, transferring the heat from that air to the fresh air being drawn into the building via a heat exchanger. Domus Ventilation’s HRXE MVHR range recovers heat with up to 95% efficiency, making it highly effective. The filtered, pre-warmed air is then distributed around the home.  If you’re yet to be sold on MVHR systems, then consider these key benefits:

1. Health
   In the UK, we spend 80-90% of our time indoors. The air that we breath indoors is therefore just as – if not more – important than the air we breathe outdoors. Sources of indoor air pollution are widespread, from cooking, cleaning products and furniture to external emissions entering our homes. In the winter months you also have condensation and mould to contend with. Poor indoor air quality has been linked to an increased risk of respiratory and cardiovascular illness, cognitive impairment and certain cancers. England’s Chief Medical Officers Annual Report 2022 Air Pollution stated: “The role of ventilation is central to reducing unavoidable indoor air pollution.” MVHR systems are the most effective ventilation method for our homes as they both extract stale air and supply filtered ‘fresh’ air to key rooms, such as bedrooms.
2. Comfort
   Breathing in poor quality air is not only unhealthy, it’s unpleasant. As stale air is usually the result of a buildup of chemicals (especially VOCs) and humidity, our homes feel ‘stuffy’ and can have an unpleasant smell. MVHR systems are continuously on, removing that stale, humid air and its undesirable odours. Furthermore, during colder months they take the chill out of the supply air by passing it through a heat exchanger where the outgoing air’s energy is extracted and transferred. In the summer months, an automatic 100% thermal bypass allows in cooler, fresh, filtered air without warming it.
3. Energy efficiency
   By reusing the outgoing air’s heat to temper the incoming air, MVHR systems help reduce the home’s heating load. The Centre for Sustainable Energy estimates heating costs can be reduced by around 25%. Whilst MVHR running costs are dependent on the property size, building fabric, occupant lifestyle etc., they are inexpensive to run. To ensure maximum energy efficiency is gained from an MVHR system though, it’s important to correctly size the unit, use good quality ducting (Domus Ventilation ducting has been third party tested for end-to-end system performance), and correctly install and commission the units.
4. Structural integrity
   If not dealt with, trapped condensation can lead to timber decay and can have a detrimental effect on insulation. More often though, it leads to mould growth on surfaces of walls and furniture. Removing large areas of mould is not easy and can be costly, especially when redecorating is required and furniture has to be replaced. What’s more, as the source of the mould hasn’t been addressed, it’s very likely it will return. MVHR systems remove humidity, reducing levels of condensation and preventing mould from forming.
5. Building Regulations
   Changes to Building Regulations ‘Approved Document F, Volume 1: Dwellings’ (ADF1) came into effect on 15th June 2022. Across all sizes of properties, minimum ventilation rates were increased. In the case of larger properties with five bedrooms, the minimum ventilation rate went from 29 to 43l/s. To achieve these new ventilation rates, mechanical ventilation systems such as MVHRs are the most proficient option.
6. Value-add
   The public are more aware than ever before of the importance of good air quality. Stories of extreme overheating in properties located in urban heat islands are also making national news. For housebuilders, an MVHR system can therefore be an attractive proposition to home buyers, providing them with good indoor air quality, added comfort and energy efficiency. These six points all provide a powerful argument for including MVHR systems into your new residential developments. So, if you haven’t really considered MVHR systems previously, isn’t it time to think again? Domus Ventilation is a manufacturer of market-leading ventilation systems that save energy and improve indoor air quality.

The post Why housebuilders should be specifying MVHR systems in their new builds appeared first on PHPD Online.