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Ventilation and air treatment: extractors, controlled mechanical ventilation (VMC), dehumidifiers...

The evolution of thermal regulations in favor of insulation and caulking imposes the need for a strengthening of ventilation. A house needs to breathe. In old housing, the poor airtightness of wooden frames is sufficient. The situation is quite different in modern houses, or in those whose original door frames are replaced by new, totally waterproof ones. For health as for comfort, it is necessary that the stale air is constantly evacuated, and replaced by fresh air. This is the role of controlled mechanical ventilation systems (VMC), air handling units, dehumidifiers, etc.


  1. Residential ventilation systems
  2. Stale air: danger
  3. Chasing the kitchen smells
  4. Fight against moisture
  5. Get better air

Residential ventilation systems

Headache, feeling of poor breathing, moisture inside the windows, mold on some walls: these are all signs that should alert you to the quality of ventilation in your home.
If it is not very old (after 1960) it has a natural ventilation. If it is more recent (after 1970), it probably has at least a system of electric ventilation, even a VMC - controlled mechanical ventilation - single or double-flow.

Ventilation and air treatment: extractors, controlled mechanical ventilation (VMC), dehumidifiers...: treatment

Natural ventilation, air circulates from one room to another from below to create a homogeneous mixing in all rooms.

Natural ventilation, air circulates from one room to another from below to create a homogeneous mixing in all rooms.

Simple flow VMC system

Simple flow VMC system

The VMC double flow: the fresh air is sucked from the outside, the stale air is extracted from the interior parts and evacuated to the outside.
It heats the fresh air via a heat exchanger.

Stale air: danger

The ventilation of a room is not, as is often believed, a source of cooling and therefore of excessive heating expenses, the circulation of air being one of the major components of any heating system; because it is the air that heats us and not the device itself. If you stop the flow of air, it will not move closer to the heat source and will not warm you up. Only radiant panels escape (to a certain extent) this rule.
It is dangerous to obstruct (As we often see!) the high and low ventilation grilles, especially in rooms where there is a gas appliance (heating, or water heater): not only does it interfere with its proper functioning, but in addition you risk, at a minimum, being inconvenienced by lack of oxygen.
If you benefit from a modern ventilation systemregularly check or have his condition checked; the fans are now silent, but you will still see without difficulty of their eventual stop.
If your house is old, and especially if you have installed PVC windows for better thermal and sound insulation, think of the need for good ventilation. Several solutions are available to you:

  • have in a number of rooms a window aerator (unattractive but effective);
  • place ventilation grilles at doors and windows (low ventilation and high ventilation) to create air circulation;
  • install a real aeration system in sensitive rooms, at least in the kitchen (where the hood is not enough).

Ventilation and air treatment: extractors, controlled mechanical ventilation (VMC), dehumidifiers...: treatment

Boasting double insulation, this direct aerator is ideal for a bathroom.

Ventilation and air treatment: extractors, controlled mechanical ventilation (VMC), dehumidifiers...: controlled

To calculate the cubage of a piece, multiply its width (L) by its depth (P) and by its height (H). The air must be replaced 10 to 15 times an hour in a kitchen.

Ventilation and air treatment: extractors, controlled mechanical ventilation (VMC), dehumidifiers...: mechanical

Modern windows have a device like this: do not plug it!

Chasing the kitchen smells

Chasing the kitchen smells

An extractor in the kitchen actively participates in the renewal of the air which corrupts rapidly (if only because of the frequent presence of burners).
The kitchen is a sensitive room, the air must be renewed.

Ventilation and air treatment: extractors, controlled mechanical ventilation (VMC), dehumidifiers...: controlled

The extractor and filter hood above the hob is now essential. Although there is often talk of hood that can work in recycling, nothing can replace a real evacuation to the open air. It should be noted that some VMCs have a box specially designed to provide the suction necessary for the renewal of air by a single duct, for the hood as for the rest of the house.
This appliance has become indispensable in any kitchen worthy of the name. Most are built-in motors, but you can also opt for a model whose engine will be placed in the attic, ensuring silence in the kitchen. The quality of the filter is essential: preferably take a model admitting activated carbon filters, more expensive but much more effective and much more durable. Some hoods operate in recycling, so without evacuation.

Fight against moisture

Excess moisture leads to the formation of condensation and mold. Ventilation is the best antidote against the process, as well as quality insulation avoiding "cold wall" phenomena. However, some homes are and will remain wetter than others. It is possible to actively fight against moisture by a simple means: the moisture absorber, consisting of a tray intermediate grid, on which we place a bag of absorbent crystals: not to be within the reach of children and pets because the crystals are highly toxic. Do not forget to empty the bin, because if the bag is calibrated for its volume, it may however overflow.

Moisture absorber

Moisture absorber

Ventilation and air treatment: extractors, controlled mechanical ventilation (VMC), dehumidifiers...: ventilation

Moisture absorbers including a plastic container, absorbent crystals, and a separator screen are readily available commercially. Just release the bag of crystals from its plastic packaging and place it on the grid: the crystals absorb moisture that is deposited in the tray. It is emptied by changing the crystals. ideal in cellars and wet cuisines.

Ventilation and air treatment: extractors, controlled mechanical ventilation (VMC), dehumidifiers...: extractors

The electric dehumidifier is a very efficient device, which should not be confused with an air conditioner, even if it can participate in the cooling of the room, then-it uses a refrigeration device to condense the water in the atmosphere under the form steam and then return the air "dried" to the room. The water must be evacuated through a pipe or collected in a tank to be emptied periodically.

  • This device eliminates up to 12 liters of water per day from the atmosphere of a 120 m3 room. This for a consumption of 380 W / h.
  • Silent, it has an automatic defrosting system and it can be optionally equipped with a device for drainage and permanent water evacuation.

Get better air

The air too dry
Too dry air also has a number of health disadvantages: dryness of the mucous membranes, skin irritation are some of these inconveniences. As there are dehumidifiers, there are devices designed to make steam and distribute it regularly in the atmosphere. The simplest continuous operation, the most sophisticated are equipped with a controller for automatic triggering as soon as the humidity level drops below the comfort threshold (40% humidity). It must be refilled with water every day, the autonomy being, depending on the model, from 12 to 24 hours, for volumes of 70 and 180 m3 respectively. Particular attention will be paid to the quality of the water, which must not be calcareous, as this may cause very rapid fouling (some models however have an automatic descaling system).

Pollution is of concern to us all; the use of appliances to improve the air quality in homes (ionizers) remains confidential. However, there are effective materials, which filter up to 98% of airborne particles (sources of many allergies) and bring down dust and pollen that have not been filtered. Externally, these devices are a bit like small air conditioners.

Air conditioning
Regulating the temperature to the nearest degree is a dream that is no longer inaccessible. If in many places a simple fan is enough to withstand the few days of heat that summer in the summer, in some areas, the air conditioner is a real comfort equipment.
Two technologies are involved: monoblocks and splits, both operating on the principle of heat exchange.
In both families, there are mobile devices and other fixed (the splits however still having the "wire to the leg" of a pipe connecting it to the condenser, located outside the house).
Also note refreshing soils and reversible systems: air conditioning in summer, heating in winter.

(photos / visuals: © DIY-Prod, except special mention)

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