VMC: the pros and cons, advantages and disadvantages

[gmac]

Here is another topic of reflection that I have right now.

Is the VMC really essential in a house???

Some houses are equipped, others not ... Often very old houses are lacking and yet it does not prevent that they are comfortable and healthy.

Currently, I live in a house of 20 years old, insulation from the inside, hollow bricks .... double glazing "perforated" by pretty air inlets. I imagine that these entries are intended for the operation of the VMC, history of not putting the house in depression.

However:

-Where there is wind, there is a lot of airflow in the house, notament because of these air intakes.

- Basically, the entry of air at the windows, it is still a significant loss of calories.


Among the three main types of VMC:

- simple flow: not really automated control, the hot air is extracted from the house, without necessarily that it is necessary.

- simple hygro-adjustable flow: A little better, the suction is done "so-called" when necessary, but still a big loss of calories.

- double flow: probably the least bad, the heat exchanger can recover calories, but the installation is binding, especially in renovation ... not to mention the price.


In short, is the VMC really useful? Would not it be an econological aberration? (a fan that pumps electricity, all that to evacuate calories).

In short, can I do without VMC in my house?

[cosinus]

For me the VMC is used to remove excess moisture in a home. I was able to judge the merits of this claim from personal experience.
There are some years I was renting a house with VMC. The previous tenant probably judging that the VMC was a source of unnecessary calorie loss had unplugged!
At first I was found out anything, after a year 1 / 2 traces of moisture began to appear in the corners, I reconnected the VMC.
So my personal experience tells me that the VMC is necessary to remove moisture from a house.
As is also true that calories are lost in this way I am now considering replacing the single flow VMC my new house by a double flow.

[I Citro]

It seems to me that the subject has been extensively treated.

Overall, it emerged that the home is, along with the automobile, an important place of concentration of pollution.
For this reason it is very important to renew the air in our homes (and automobiles), simply to evacuate the accumulations of pollutants.

This results in an immediate gain in comfort and sanitary quality:
Elimination of humidity, risks of mould, allergens, carcinogens, improvement of thermal comfort which deteriorates if the % humidity increases.

The additional energy expenditure caused by air management is largely amortized by the gains made.
The fact remains that a more natural management can be envisaged according to the dwellings (thermosiphon for example).
However, the increased sealing of modern constructions and the increase in polluting emissions (aerosols, cleaning products, toxic fumes from furniture, paints, floor and wall coverings, etc.) require large renewal coefficients.

That's basically the theory, the pros in the field can back it up with numbers.

[gmac]

Thank you for your feedback !

In this case, I will move towards a Hygro A. with mouths that go well. I also hope to find a noisy model (I would probably hang it on lines to limit transmitted vibrations.)

This will be my work next weekend I think ^^

[I Citro]

In this case, I will move towards a Hygro A. with mouths that go well. I also hope to find a noisy model (I would probably hang it on lines to limit transmitted vibrations.)

This is the way to proceed.

[bham]

Formerly there was indeed no VMC because the houses were not insulated, the water vapor, let's say the ambient humidity could migrate from the inside to the outside, exceptions made of naturally humid regions including style of housing based on solid bricks for example as the north of France, the bricks being particularly hydrophilic.
With the era of the first insulators, i.e. glass wool and polystyrene which, in interior insulation, constituted a barrier to the migration of water vapour, polystyrene being not very permeable, unlike glass wool which on the other hand, being very hydrophilic, it had to be laid with a vapor barrier.
So the walls no longer "breathe", it was necessary to find a stopgap and it was the CMV. Who said VMC said air vents at window level. However, I have heard that to renew the indoor air, 15 minutes / day is sufficient by opening a window.
In short today, new insulators have appeared and to answer your gmac question, I think that it must be possible to do without VMC if one uses insulators insensitive to water vapor and sufficiently permeable to the latter and if you insulate from the outside, use sufficiently hygro-regulating building materials such as lime, earth, wood, for example.
Personally I have a very old house in which I found masses of natural insulation: sound, envelopes grain seeds. They placed them on the ceiling, between the beams, and hid the whole thing with plaster. And it's very nice when you renovate and it falls on your head. It was their insulation, very permeable to water vapor and hygroregulator. I even heard that in a castle in the region, they found as insulation .... pig bristles (long haired I guess).

[gmac]

Thank you for this history of the VMC.

Like the house at 20, it is fitted with polystyrene interior insulation and hollow bricks for the exterior. Even if it's not great, I think there is a way to have "not too catastrophic" results with this type of insulation. What is catching most at the moment are probably the old double glazed / wood windows that are no longer waterproof.

Anyway, this has already been covered in another post.

The important thing for now is my VMC.

In fact, when you look at large DIY stores, the choice is relatively "poor". At most one or two hygro A.

I will certainly move towards an ALDES or an Atlantic. 4 sanitary connections + 1 kitchen. It should be around 350 €.

However, I have a few questions:

-> how does a humidity sensitive extraction outlet work? On all the sites, it works more or less by "magic" with a cord which retracts according to the humidity. Is it a chemical phenomenon ???? There is no electronic / electric piloting?

-> I also saw that there were also inlet vents to be fixed at window level. Some are also humidity sensitive. What to think of these types of products?

Sorry if my questions deviate a little more to the DIY side than the econological one.

[elekaj34]

Hello

For my part, I have a VMC (I posted the same comments as you there is little) https://www.econologie.com/forums/question-sur-vmc-et-chauffage-t4218.html

I tried not to air during 1 weeks.
Results, the bad smells supposed to be evacuated by the VMC remain, and then the heating is there to collapse, it takes almost 4 to gain 1°C whereas in normal times I put 3/4h to 1H.

So I resumed the daily aeration of 1 / 4h per day.

Advantages: The air is cooler, seems to be less heavy to breathe, more efficient heating.

By cons, not having the right to cut the VMC (which at home is done by plugging mouths), I resigned myself to see the warm air fly away: /

Sincerely,

[bamboo]

Hello,

-> how does a humidity sensitive extraction outlet work? On all the sites, it works more or less by "magic" with a cord which retracts according to the humidity. Is it a chemical phenomenon ???? There is no electronic / electric piloting?

In my old apartment, I had humidity-controlled extraction vents. It's great for the SDB. Really very effective.
I don't know how it works, but it's not powered => neither electronic nor electric.

-> I also saw that there were also inlet vents to be fixed at window level. Some are also humidity sensitive. What to think of these types of products?

I think this is of much less interest: it is not especially the humidity of dry rooms (where the air inlets are placed) that must be measured, but rather that of damp rooms => I think that it is rather necessary to put the budget in the humidity sensitive extractions.

A+

[jonule]

Hello,
I just moved into an old house, big 50cm stone walls.
there is no VMC, I asked myself the question and I had a hygrometer / T ° C 20 € to carouf;

I've always heard "a house is ventilated 5 to 10 minutes a day" without VMC it works very well I see my parents' house and I renew: it's very healthy for the house!

for the "modern cocooning lazy" it's on the CMV it's more practical, but it consumes (well not much) we can not have everything! -)

scratching the lead paint and the wallpaper I find lime plaster on the old stones of the peripheral walls and the hollow bricks partition walls: the walls breathe I have no accumulation of moisture, it's the same for the under roof the insulation is always dried by the air which passes under the roof, which avoids the rain!
therefore unnecessary to put a "vapor barrier rain brake" with a technique such as straw bale coated lime outside (fire barrier + anti rodent) interior earth coating (humidity regulation), which is sold only by sellers of "vapor barrier brake rain" ;-)

when the sun is out during the day and the weather is good in the house after eating and/or having a coffee, it's time to turn off the heating and open the door and the windows.

this problem only arises in winter I think ...

in order not to have humidity on the windows (or the "corners" hihi) just close the shutters!

but for the "faignat .... yes we know, there are remote controllable or even automatic plastic shutters

just find the way (lao tzu)!

so good thinking.


otherwise I think a VMC double flow keeps the house in overpressure, for the spread of heat from room to room?