Is decentralised MVHR noisy?
A well-designed and properly installed MVHR system is not noisy. Helty decentralised MVHR units stand out for their acoustic performance: both the wall-mounted MVHR models and the wall-recessed Flow30 and Flow40 units have a minimum sound pressure level of just 18 decibels.
Noise generated by building services is one of the most common concerns for both designers and end users, whether it comes from air-conditioning systems or from air renewal and treatment systems.
In general, air renewal systems follow the same principle as other domestic building services: when properly designed and carefully installed, a Mechanical Ventilation with Heat Recovery system is not noisy.
In the case of decentralised MVHR, the main sound sources responsible for noise generation are essentially the rotation of the electric fans installed inside the ventilation unit and the airflow noise produced as air leaves the room terminals.
Quiet operation is a particularly important parameter for this type of MVHR system, as the ventilation units are installed directly in occupied rooms, often in bedrooms. These are precisely the spaces where condensation-related mould problems are more likely to occur and where adequate air renewal should be ensured without having to open the windows.
When selecting the best decentralised MVHR system, operating noise must therefore be considered alongside other essential parameters, such as air renewal flow rates, heat recovery efficiency and air filtration level.
Which data should be considered: sound power or sound pressure level in the room?
Although both are measured in decibels (dB, the unit used to measure sound), they refer to different measurements and cannot be directly compared.
In simplified terms:
- Sound power, or acoustic power, identifies the absolute amount of noise emitted by the MVHR unit.
- Sound pressure, or acoustic pressure, is a relative value referring to the noise perceived within a given room, taking into account the position of the sound source and the characteristics of the room itself.
This explains why the sound power value is usually a few decibels higher than the sound pressure value. When comparing different products, it is important to ensure that sound power data are not being compared with sound pressure data, or vice versa. Likewise, when comparing sound pressure values, the measurement conditions must be the same.
For example, Helty wall-mounted decentralised MVHR models, as well as the wall-recessed Flow40, have a sound pressure level of just 18 decibels, measured in a 30 m² semi-anechoic room at a distance of 3 metres, compared with a sound power level of 29.5 decibels. Both values refer to the first air renewal speed.
To ensure transparency and accuracy for designers, installers and end customers, Helty has chosen from the outset to publish both values in its product data sheets and catalogue.
These figures give Helty decentralised ventilation units a significant advantage in terms of acoustic performance, a parameter that is becoming increasingly decisive in purchasing decisions.
In case of doubt, customers can always contact a partner retailer where a working product is available and request a demonstration. This makes it possible to experience first-hand how Helty decentralised MVHR stands out not only for its effectiveness and design, but also for its exceptionally quiet operation.