Bathroom ventilation: which one to choose?

Choosing your bathroom VMC can be complicated because there are different models. However, we do not miss this purchase, the Controlled mechanical ventilation preserving the building and allowing the occupants of a dwelling to benefit from healthier indoor air. Since the VMC bathroom considerably reduces the humidity level, it preserve health some people, good condition of materials and has many other advantages. Let’s see in detail the interest of installing a VMC in a humid room such as the bathroom, and take stock of the criteria for choosing a VMC.

Why install a VMC in the bathroom?

In the bathroom (or in the shower room), a large amount of steam is produced every day following the baths and/or showers taken by all the members of a family as well as the guests. If we do not act daily against the condensationthis environment quickly becomes unhealthy. Indeed, in a very humid atmosphere, micro-organisms and fungi develop in no time and can be the cause of allergies. At the same time, the humidity generated reaches the walls, the joints, the ceiling, the floor, and all the materials gradually deteriorate. With the kitchen, the bathroom is therefore a wet room which must be equipped with a device capable ofpurify the ambient air.

In addition to ventilating your bathroom every day by simply opening the window whatever the weather, it is essential to install Controlled Mechanical Ventilation (VMC), an even more fundamental necessity when the room does not have a opening to the outside.

It should be noted that the VMC is as useful in an old dwelling as in a new dwelling, because the latter benefits from a extreme insulation. This is perfect for reducing energy losses and therefore your heating bill. But it can have a perverse effect since the dwelling is particularly airtight. However, if it is well ventilated, new ultra-insulated housing displays low energy losses, which allows occupants to live in a comfortable and healthy environment.

Know the different types of VMC to refine your choice

The operating principle of Controlled Mechanical Ventilation is quite simple to understand. Its motor is connected to an extraction mouth by a network of ducts. L’stale air is evacuated to the outside whileNew air enters the room (in this case the bathroom). There are two types of VMC in dedicated stores.

La VMC simple flux

The stale air is extracted from the bathroom by an extraction vent placed in the ceiling then passes through the duct to be evacuated to the outside. It is thanks to a turbine that the air circulation is ensured. Fresh air then enters the room through the vent. For information, sheaths of a 80cm diameter are recommended for a bathroom.

One can criticize this simple flow Controlled Mechanical Ventilation for being quite noisy. It is better to place your engine in the attic, for example, if they have good sound insulation. On the other hand, she is very easy to install since it only requiresa single duct network. Unless you are experienced in installing VMC, it is preferable to entrust this task to a professional.

Two categories of single-flow VMC are available. The self-adjusting model allows air renewal constant ensured thanks to the power of the motor and the diameter of the duct without any need to resort in parallel to a control system external to the VMC. The self-adjusting single-flow CMV is the minimum solution to install at home if you don’t have a big budget and/or if there is little humidity, which is not really the case in a bathroom.

The humidity sensitive model ensures air extraction and regulates its flow according to the indoor humidity level thanks to vents that are sensitive to the degree of humidity in the bathroom. The humidity sensitive model also regulates the flow of air to be extracted according to the humidity level.

There exists a VMC hygroréglable A intended for tertiary buildings and to collective housing. The price is reasonable, the power consumption and heat loss are moderate. For more precise control of the airflows in an individual dwelling, one can opt for a VMC hygroréglable B which meets the current standard for new constructions. This model is more expensive to purchase than the others, but it allows better control heat loss.

La VMC double flux

She owns two different networks, each with its own fan. The first network manages the evacuation of stale air and the second network is intended to bring fresh air into the home. This is the type of CMV that is recommended in a maison passivethat is to say whose energy consumption per square meter is minimum. A double flow VMC is rentable only in this type of accommodation.

Here again, there are different types of double flow VMC:

  • Classic : most commonly installed model. Heat loss is minimal since it blows heated air.
  • Thermodynamics : expensive to buy, it is coupled to the heat pump (heat pump), so that it represents, in addition, a solution for heating the accommodation.

Due to the obligation to have two duct networksl’installation of a double flow VMC is enough complex. The use of a professional is therefore essential.

Before choose your double flow VMCit is important to consider the following points:

  • The fashion the functioning : we opt either for a self-adjusting if you want non-stop operation (quite energy-intensive), either for a humidity sensitive more energy efficient because it only starts when the humidity level in the bathroom is too high.
  • The air flow : it must be adapted to the volume of the room (or, for an entire dwelling, to the volume of all the rooms). Its method of calculation is simple since it suffices to divide this volume by 24 in order to obtain the minimum flow necessary for a VMC. He is expressed in m3/h (cubic meters per hour).
  • The yield : professionals recommend a yield of 85 % minimum. The higher it is, the more economical the CMV.

A VMC being more difficult to install in an old dwelling, there is a alternative whose effectiveness has been proven: the VMP or Punctual Mechanical Ventilation. These are air extractors to be placed in the bathroom. Each aerator is independent. Today there are electric extractors and other more economical models, operated by the simple force of the wind, allowing a natural ventilation. Everyone can therefore find the VMP perfectly adapted to the volume of their bathroom.

Finally, the prix counts for a lot in the choice of a single flow VMC or a double flow VMC even if it should not be the first selection criterion. It is necessary to count a minimum of 80 € for a single flow CMV and at least 120 € for a humidity sensitive one of this category. The budget is higher for a double-flow CMV: at least €360 for a medium-efficiency model, and between €800 and more than €3,000 if you set your sights on a high-efficiency model. The best VMCs are those that consume little energy and have a excellent performance at least 85%. They are certified NF VMC or NF 205.

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