A Guide to Quieter Ventilation: Units, Ducting and Air Valves Explained
A Guide to Quieter Ventilation: Units, Ducting and Air Valves Explained
Quiet ventilation starts with good system design. While many people focus on the MVHR unit, extractor fan or air valve itself, the overall noise level of a ventilation system is affected by several factors, including unit size, duct layout, air speed, ducting type, air valve selection and commissioning.
If a ventilation system is too small, poorly routed or incorrectly balanced, it may need to work harder than necessary. This can increase noise, reduce comfort and affect long-term performance.
In this guide, we explain how to make ventilation quieter by choosing the right size of unit, using suitable ducting, selecting the right air valves and considering a professional ventilation design service.
What makes a ventilation system noisy?
A noisy ventilation system is often caused by air moving too quickly through the system or by components being incorrectly sized for the airflow required.
Common causes of ventilation noise include:
- An undersized ventilation unit
- Fan speeds running too high
- Ducting that is too small
- Too many bends or restrictions in the ductwork
- Poorly fitted or unsuitable air valves
- Air valves being closed down too far
- Lack of silencers or attenuators
- Poor commissioning after installation
A quiet system is not usually achieved by one product alone. It is the result of the right products being selected, designed and installed correctly.
Choose the right size ventilation unit
One of the most important steps in reducing ventilation noise is choosing the correct size of unit for the property.
If a unit is too small for the required airflow, it may need to run at a higher fan speed for longer periods. This can make the system louder and may place more strain on the unit over time.
A correctly sized MVHR unit, MEV unit or extractor fan should be able to deliver the required airflow without constantly running near maximum capacity. This helps keep noise levels lower and supports better long-term performance.
When choosing a unit, consider:
- Property size
- Number of rooms
- Required airflow rates
- Number of wet rooms
- Ductwork layout
- Available installation space
- Whether the system is for a new build, retrofit or renovation
For whole-house systems, a professional ventilation design can help make sure the unit is suitable for the property rather than simply choosing based on price or basic room count.
Why ducting matters for quieter ventilation
Ducting has a major impact on how quiet a ventilation system feels in the home.
If ducting is too narrow, too long or full of sharp bends, the system has to work harder to move air through it. This can increase resistance, airflow noise and fan noise.
Good ducting design should aim to keep air movement smooth and efficient. This usually means using the correct duct size, avoiding unnecessary bends and keeping duct runs as direct as possible.
For quieter ventilation, consider:
- Correct duct sizing
- Smooth internal duct routes
- Fewer sharp bends
- Secure duct connections
- Suitable silencers where needed
- Good quality ducting components
- Proper sealing to reduce air leakage
In MVHR systems, semi-rigid radial ducting can be a good option because each room has its own dedicated duct run from a manifold. This can help with airflow control and reduce the risk of noise transfer between rooms when the system is designed correctly.
Which air valves are the quietest?
The quietest air valves are usually the ones that are correctly selected, correctly sized and correctly commissioned for the airflow required in the room.
It is not only about choosing a “quiet” air valve. Even a good quality air valve can become noisy if too much air is being forced through it or if it has been closed too far during balancing.
For quieter air valve performance, consider:
- The airflow rate required for the room
- Whether the valve is being used for supply or extract
- The valve size
- The valve design
- The location of the valve
- The ductwork connected to it
- Whether the system has been commissioned correctly
A larger or better-suited air valve may allow air to pass through at a lower velocity, which can help reduce noise. Air valves should also be positioned carefully to avoid draughts, whistling or direct airflow over areas where people sit or sleep.
Supply valves vs extract valves
Air valves are generally used for either supply air or extract air.
Supply valves deliver fresh air into living spaces such as bedrooms, lounges, dining rooms and home offices.
Extract valves remove stale or moist air from wet rooms such as bathrooms, kitchens, utility rooms and en-suites.
Both types need to be selected and balanced correctly. If an extract valve is too restricted, it may create unwanted airflow noise. If a supply valve is poorly positioned, occupants may notice draughts or sound from the air movement.
Can closing an air valve make ventilation quieter?
Closing an air valve may seem like a quick way to reduce airflow noise, but it can often make the system worse.
If an air valve is closed too much, it can increase pressure and create a whistling sound. It can also affect the balance of the whole ventilation system, meaning other rooms may receive too much or too little airflow.
Air valves should be adjusted as part of proper system commissioning, not randomly closed to reduce noise. If a valve is noisy, the issue may be related to airflow rate, duct sizing, fan speed or system design.
Use silencers and attenuators where needed
Silencers, also known as attenuators, can help reduce noise travelling through ventilation ductwork.
They are commonly used near MVHR units, in duct runs where sound transfer is a concern, or where ventilation noise needs to be reduced in sensitive rooms such as bedrooms and home offices.
Silencers are most effective when included as part of the design stage, as they need enough space and the correct duct connections. They should not be treated as a fix for a poorly designed system, but they can be very useful in a well-planned quiet ventilation setup.
Commissioning is essential
Even with the right unit, ducting and air valves, commissioning is still essential.
Commissioning is the process of testing and adjusting the airflow at each valve so the system delivers the correct amount of air to each room. This helps the system work efficiently and quietly.
Without commissioning, some rooms may receive too much airflow while others do not receive enough. This can lead to noise, poor ventilation performance and an uncomfortable indoor environment.
A properly commissioned system should provide the required ventilation without excessive fan speeds or noisy air movement.
How to make an existing ventilation system quieter
If your current ventilation system is noisy, there are a few things to check before replacing the unit.
Possible steps include:
- Check whether filters need to be cleaned or replaced
- Check that air valves have not been closed too far
- Inspect ducting for restrictions or crushed sections
- Make sure grilles and terminals are not blocked
- Check whether fan speeds are set correctly
- Consider whether silencers could be added
- Have the system checked and recommissioned
If the system was not designed correctly, there may be limits to how much it can be improved without changing ductwork, valves or the unit itself.
Why professional ventilation design helps reduce noise
A quiet ventilation system is much easier to achieve when noise is considered at the design stage.
A professional ventilation design can help make sure the system uses the right unit, duct sizes, air valves, duct routes and accessories for the property. It can also help reduce the risk of high fan speeds, poor airflow balance and unnecessary noise.
This is especially useful for MVHR systems, whole-house ventilation projects, new builds, renovations and properties where comfort is a priority.
Quiet-Vent design service
If you are planning a ventilation project and want to reduce the risk of noisy airflow, the Quiet-Vent design service can help.
Quiet-Vent can support your project with a ventilation design that considers the layout of the property, required airflow rates, duct routes, unit selection and air valve positioning. This helps create a more balanced system that is designed for comfort, efficiency and quieter operation.
A good design can help you avoid common issues such as undersized units, excessive duct resistance, poor valve placement and difficult commissioning.
Send your plans for a free ventilation design today.
Final thoughts
The quietest ventilation systems are not created by one product alone. They are created through good design, correct sizing, suitable ducting, appropriate air valves and proper commissioning.
If you want quieter ventilation, start by looking at the full system rather than just the visible air valves. Choosing the right unit size, planning duct routes properly and using the correct components can make a big difference to comfort and noise levels.
For support with your ventilation project, explore the Quiet-Vent design service and get a system planned around your property from the start.