VMC or VMR?

[Syliodj]

Hello,
My two questions again on the forum, , a bit of a handyman but not well-versed in ventilation, concern a choice of ventilation system. I have read all the previous posts on the matter but still hesitate.
Sorry if my message is going to be a bit long ( ) but I think I have to explain the framework of my questions ... that I ask myself for a small house in the Gard which dates from 1850, in stone, not insulated, with an impressive thickness of walls (50 cm) and old-fashioned plaster on the inside and simple cement plaster on the outside.
We will probably not be able to live there for a year and we have the problem of humidity when it is closed (we live 2 ½ hours away and therefore will not be able to come every weekend).
Upstairs, living room, kitchen, bathroom, wc, 2 bedrooms for approximately 56 m² and 140 m3. Above, an attic isolated by a layer of glass wool on the ground (on a slab) and more than 2 meters high at the lowest point.
Downstairs, a summer kitchen with a laundry room behind (in which I will install sanitary shower, washbasin wc), for about 30 m² and 62 m3 plus 3 cellars, one of which contains a gas boiler on a fireplace and communicates with the laundry room by the passage of the heating pipes.
Small peculiarity, in the back of the laundry room (at ¾ buried on the back), a free water inlet of excess rainwater infiltration during "Cevennes episodes" (persistent thunderstorms in the rainy season) which infiltrates into a channel dug for this purpose for ... ages? ... But this is the subject of our concern in terms of humidity although the house has been doing this for decades!

Question 1: I hesitate for the top between a VMC hygro B low consumption 3-4 pieces on kitchen, bath, wc, or a permanent VMR on the bath only (currently equipped with a mini VMR triggered on the light) knowing that my companion systematically opens the windows in all seasons and that we are considering a small fireplace in the living room for 2 years.
Your opinions ?

Question 2: While waiting for me to resolve the issue of the arrival of excess rainwater in the laundry room (located below the upstairs bath) with a mason from the village, I am considering an air extraction in the laundry room (equipped with a free exit) but which will suck as much from the summer kitchen (hole in the existing wall) as from the cellar equipped with the gas boiler mounted on a fireplace (passage of the heating pipes).
Your opinions ?

Thank you in advance for your replies…

[antoinet111]

the solution of the vmc hygro seems correct to me, but in your case, what scares me the most is that you have "period" breathable walls, but closed by cement, which is not the less of the world breathable.
I would be a little more afraid of the degradation of the walls.

but for having lived in the same type of house as you, with also a semi-buried part and without vmc, I assure you that it is a disaster level mushrooms ...

Note that for hygro it is very useful to know the relative humidity peaks outside in rainy weather, because they start all the time. (I am in Finistère)

[oiseautempete]

that I ask myself for a small house in the Gard which dates from 1850, in stone, not insulated, with an impressive thickness of walls (50 cm)
Question 1: I hesitate for the top between a VMC hygro B low consumption 3-4 pieces on kitchen, bath, wc, or a permanent VMR on the bath only (currently equipped with a mini VMR triggered on the light) knowing that my companion systematically opens the windows in all seasons and that we are considering a small fireplace in the living room for 2 years.
Your opinions ?

When installing permanent mechanical ventilation, the house must be kept closed otherwise all the benefits will be lost, that is to say: reduction of heat loss in winter and maintains interior freshness in summer, especially more efficient with massive walls ... and it also prevents the introduction of critters into the house ...

[aerialcastor]

what scares me the most is that you have "period" breathable walls, but closed with cement, which is not in the least breathable.
I would be a little more afraid of the degradation of the walls.

+1
You will never solve the moisture problem, as long as this cement plaster is in place.
Not to mention the structural disorders that the presence of water in the walls will create

[moby25]

Good evening

here, I am studying what I could do in terms of ventilation in my house.

FYI, I had my old wooden joinery replaced not very waterproof by PVC double glazed windows bcp more waterproof.

I just have a double double glazed door with an aerator above the window. So it's not very ventilated anymore.

As you can imagine, I feel myself between a VMC or a VMR.

Concerning the CMV:

- I don't have much room to put one. In principle feasible in a small, gently sloping attic, but not too much space. A "flat" vmc should be able to fit.
- I'm afraid the flow is too high. I have small volumes.
I had seen a post where someone said that the VMC pumped all the heat.

VMR:

- simpler to implement.
- from what I read it is also to see better than a CMV. (the vents and ducts are almost never serviced).

http://humidite.comprendrechoisir.com/c ... e_repartie

http://conseils.xpair.com/consulter_par ... partie.htm

By cons I do not know what to put as an extractor, hygro, not hygro.

If anyone has any experience in this. (hygro for the bathroom for example, manual for the kitchen etc ...)

Another question, whether for VMC or VMR, what type of air intake did you put.

Thank you

[Syliodj]

Hello,
first of all my apologies for having delayed in answering ...

For Aintoinet111, OiseauTempête and AerialCastor, the walls, according to the local mason I had brought in, are covered with a mixture that allows breathing ... I am reassured. I am not a mason!
Indeed, in the main body of the 160-year-old house, no trace of humidity or fungus.
Our fear of humidity actually came from the statements of the former owner who she had bought from Englishmen who only came in the summer and left the house closed without ventilation or heating. But the house held up well despite this.

Then, I bought a hygrometer from a well-known DIY store for about twenty euros with recording of the minimums and maximums in order to study the situation. The daily variations go from 35-40% to 55-60% humidity with peaks towards 75-80% during heavy rain of the well-known Sevenol type episodes ... but this humidity quickly returns to normal at the end of the rains.
Finally, the dreaded humidity is no worse than in an ordinary house.

I have often been told to observe the house before making any decisions, and that sounds good to me.

So I just installed a basic single flow VMC (Aldes Sekoia) which works very well and fulfills its role. I am away for 2 and a half weeks with VMC and minimum heating and I will see if the humidity measurements are stable.

For Moby25 and all of you, I did not decide on a hygro variable CMV (which in principle always appeals to me a lot) to reduce the cost of the installation because the Gard professionals that I contacted all told me that in living in such a stone house, the CMV was of the order of the superfluous and was only justified for prolonged absences.

It all depends on the type of house in which the installation is planned, surface area, type of construction and insulation.
For Moby25 again, I also have double glazed PVC windows but I must admit that we live with windows open 8 months out of 12! It's the Gard!
The CMV will work in cold weather if I may say so.
Because we saw clearly by taking possession of this house that we very quickly dried it in the cellar where there are water passages: All the professionals who came were not surprised ... They saw many houses under which and in which passes water but the passages are planned, they should not be blocked and the houses which are between 1 and 2 centuries old are still there without damage!

For the air inlets of the CMV, the openings were made not on the windows but on the top frame. The operation gives complete satisfaction.
In my case, I had no problem with space, hence the VMC in the attic with insulated ducts. For your Moby25 case, if space is really lacking maybe you can consider two extractors with 2 hygro variable speeds and switch for bath and kitchen ... solution to be criticized by other DIY enthusiasts ...

Good evening and thank you for your answers.

[moby25]

This evening I had 55% relative humidity, I opened my 2 French windows and at the same time not 5 minutes I went to 45%.

And I lost a little less than 1 ° C.

We can see that ventilation dramatically lowers the humidity level.

So indeed at the level of humidity even without ventilation it is not bad, but with a ventilation I go much lower quickly. I also evacuate bad smells and potential VOCs.

So I will have to find the ventilation / heat loss compromise

[moby25]

I saw that now we were also talking about VNR: reinforced natural ventilation. So no engine.

What do you think, because on paper it doesn't look bad at all!

http://www.acthys-gie.fr/index.php?SRubID=80&RubID=86

[moby25]

I have read tons of post about vmc and given my situation I don't think about installing one.

- I have no humidity problem: currently - 50% (wooden frame + a part in cellular concrete) with just a hygro air inlet on a window frame

- VMC ducts which are not cleaned regularly are nests for microbes.


I am thinking of going for a hygro aerator for the bathroom in case of shower / bath.

There remains the question of the kitchen. I am in "open-space" kitchen, living room, SaM.

I tate to a hygro or constant low flow.

I also have to choose the type of air intake that will be in this room. Either a humidity sensitive, or one with manual opening / closing of this type

[Syliodj]

This idea of ​​VNR, I did not come across it at the time of my research and the observation of our new home was not long enough to opt for. But that appeals to me a lot ... and I think that its effectiveness must depend as much on the type of construction as on the organization of the rooms as well as on its occupation.

Your type of house (wood frame and cellular concrete in part) should normally be able to accept this NRV well! I had considered cellular concrete for a previous house in view of its breathable qualities (abandoned for budget reasons because at the time BC was really more expensive).

In our case, we wanted a CMV for our periods of absence the first year by considering disconnecting it for the 8 out of 12 months during which we will live windows open from next year (my partner is a fervent follower and I do not know 'don't complain! ).

For information, we also have in our kitchen a manual opening of the type you show (Gas safety).

For the bathroom aerator, I strongly recommend a hygro therefore not coupled to the light (which I found in our new house in Gard which is nonsense to couple a hygro extractor to the light because as soon as you turn off, there is no more power but in fact, by dismantling this extractor, it was not hygro but tempo, contrary to what our saleswoman had told us!).

So much for my comments, so good choice for you and good installation.