ventilation renovation by VMI, am I crazy?

[nutt]

Hello everybody
I have been asking myself a lot of questions for some time. Indeed we have undertaken a change of boiler (for pellets), (modest) insulation work ... and as I cogitate, lots of questions come up.

I am wondering about the ventilation of my house. I hope you can help me.

It is an old town house renovated in the 70s by the former owners. The approximate volume is 500 m3.
The insulation is still to be improved but is not ultimately catastrophic.

We have a little humidity but nothing serious. It is just after the shower in the bathroom; so-so.

For the moment there is natural ventilation with ventilation grilles in some rooms.

As we are going to improve our insulation, that ventilation is still important in a house, we want to improve it.

With this new pellet boiler, it is not possible for me to install a vmc (because of the depression that would hinder the draft of the boiler and therefore the dangers that follow, monoxide ....)

So I rummaged in and discovered the VMI which is none other than the opposite of the VMC.

However from what I could find as info, it's expensive. It is out of the question for us to spend 2000 or 3000 € for that.

So I thought maybe I could tinker with something.

Tell me what you think. There are still many questions that arise. maybe you can help me.

Step 1 - I buy a basic vmc and mount it upside down.
1st question: Will the flow be sufficient to breathe air into the house?
Does it have to run all the time (consumption?)

Step 2 - I create a box in which I circulate the air capture outside before blowing it. In this box I there would be filters among other things.
2nd question: should we add a rubson style dehumidifier?

Step 3 - I heat the air before blowing it into the house.
3rd question: install a resistor that consumes where to circulate the duct near the radiators or the boiler.

Step 4 - the air leaves through the house vents


Another question this time on humidity sensitive systems to reduce consumption.

Can I install a vmc hygro upside down (in step 1)?
What will happen ? Will the engine start depending on the humidity? So there is a probe to install?

Well I hope to be clear.

Thank you in advance for your clarification.

Nutt

[Forhorse]

I do not know ... but a detail however, I believe that a humidity-sensitive VMC does not agitate at all on the engine, this one turns all the time, it is just that the opening of the mouths of aspiration and / or that of air intake depends on the humidity level.

[I Citro]

With this new pellet boiler, it is not possible for me to install a vmc (because of the depression that would hinder the draft of the boiler and therefore the dangers that follow, monoxide ....)

Are you sure.
Just yesterday I was at a friend's house and her pellet stove was connected to a suction cup, so no influence on the air flows from the house and no risk of combustion gases being released into the living space.

So I rummaged in and discovered the VMI which is none other than the opposite of the VMC.

Well, I don't quite agree ...
The VMI puts the house in overpressure so it increases the comfort felt but it must properly evacuate the air from humid rooms and as there is overpressure, there is electrical overconsumption.
In addition, the VMI rejects even more heated air outside therefore increases the thermal consumption of the home, like the single-flow VMC ...

[nutt]

With this new pellet boiler, it is not possible for me to install a vmc (because of the depression that would hinder the draft of the boiler and therefore the dangers that follow, monoxide ....)

Are you sure.
Just yesterday I was at a friend's house and her pellet stove was connected to a suction cup, so no influence on the air flows from the house and no risk of combustion gases being released into the living space.

Yes it is a natural draft boiler.

So I rummaged in and discovered the VMI which is none other than the opposite of the VMC.

Well, I don't quite agree ...
The VMI puts the house in overpressure so it increases the comfort felt but it must properly evacuate the air from humid rooms and as there is overpressure, there is electrical overconsumption.
In addition, the VMI rejects even more heated air outside therefore increases the thermal consumption of the home, like the single-flow VMC ...

I do not understand.
A vmc brings out the hot (and humid) air by extracting it to bring in cold air everywhere in the house by the ventilation of the windows for example.
The mvI brings in cold air and pushes the hot air out.
For me it is the same. There is no more hot air exhausted with the vmi than with the vmc.

And why, in overpressure, there is overconsumption of electricity?

[nutt]

up

I really want to hear your opinion.

[minguinhirigue]

There are five things to consider:
- natural ventilation, linked to the tightness of the openings, to the differences in external pressures due to the wind, to the difference in temperature (can be harmful in winter if the house is not waterproof, or if the users do not ventilate enough their accommodation)
- the vmc single continuous flow, which extracts hot air from humid rooms, and brings in fresh air (the operation is not great with a boiler with air intake in the house *, and losses of hot air are not negligible)
- the hygro-adjustable vmc, which varies the extract air flow according to the presence of pollutants, installed for example in humid rooms, it limits the losses of hot air to the strict minimum (it can be programmed to trigger at home business hours).
- the vmc by insufflation, or vmi, which avoids the feeling of cold, increases the draft of the heaters with air intake in the house *, has losses of hot air equivalent to those of a vmc single flow classic . Generally less sensation of drafts (leakage of openings), but less good regulation of humidity (humid rooms are no longer the main points of evacuation of stale air).
- the double flow vmc with exchanger, whose exhaust vents are in the humid rooms, ensures the recovery of calories from the outgoing air flow, and is generally adjusted to put the house in over-pressure (no drafts air). But it is more expensive.

Personally, in your case, I checked that the air inlet of the boiler is in the heated volume (natural draft does not necessarily mean that the combustion air is taken in the air volume of the house ). If so, I will leave natural ventilation.

Otherwise, I will choose a hygro-adjustable vmc for the wet room, or a double-flow vmc according to my means ...

[Korben Dallas]

A VMI is often (all the time?) Equipped with a resistor to heat the injected air. It must consume a lot ...

I have an offer from a "specialized" company which offered me this as a miracle solution to save energy. The integrated resistor is 1140W anyway. Installed price: 2300 €
He told me that it was mounting in place of the existing CMV ... which leaves me perplexed because it will push the stale air from the wet rooms to the dry rooms!

[nutt]

There are five things to consider:
- natural ventilation, linked to the tightness of the openings, to the differences in external pressures due to the wind, to the difference in temperature (can be harmful in winter if the house is not waterproof, or if the users do not ventilate enough their accommodation)

For the moment this is what we have. Air vents on double glazed pvc windows, some grids in the walls here and there (which must surely ventilate the wall linings).
We are not unhappy our house is not extremely humid but it could be better and especially in the bathroom!
But this one is right next to the boiler (yes our house is oddly organized ) so you cannot use a vmc.
We have had confirmation from the installer, it is a natural print that takes the air out of the room.

- the vmc single continuous flow, which extracts hot air from humid rooms, and brings in fresh air (the operation is not great with a boiler with air intake in the house *, and losses of hot air are not negligible)
- the hygro-adjustable vmc, which varies the extract air flow according to the presence of pollutants, installed for example in humid rooms, it limits the losses of hot air to the strict minimum (it can be programmed to trigger at home business hours).

So all this is impossible because of the boiler.

- the vmc by insufflation, or vmi, which avoids the feeling of cold, increases the draft of the heaters with air intake in the house *, has losses of hot air equivalent to those of a vmc single flow classic . Generally less sensation of drafts (leakage of openings), but less good regulation of humidity (humid rooms are no longer the main points of evacuation of stale air).

I had thought of installing my vmc upside down in the attic lost just above the bathroom, trying to recover a little heat by running the ducts along heating pipes which pass to the attic and then breathe into the boiler room. I would have to plug everything into a programmer to only trigger the system from time to time. (for example morning, noon and evening 30 minutes each time)
The rest of the time we would find our natural ventilation.

- the double flow vmc with exchanger, whose exhaust vents are in the humid rooms, ensures the recovery of calories from the outgoing air flow, and is generally adjusted to put the house in over-pressure (no drafts air). But it is more expensive.

The double flow could perhaps be suitable by blowing near the boiler. But very difficult to implement to take full advantage of it. We have two adjoining buildings and therefore very very thick walls, it would be very complicated to pass ducts to distribute the air in the house (even impossible, it would require two groups vmc). No, because if I invest in a double flow, it is not just to ventilate my bathroom and blow on my boiler !!!

Thank you very much in any case!

[nutt]

A VMI is often (all the time?) Equipped with a resistor to heat the injected air. It must consume a lot ...

I have an offer from a "specialized" company which offered me this as a miracle solution to save energy. The integrated resistor is 1140W anyway. Installed price: 2300 €
He told me that it was mounting in place of the existing CMV ... which leaves me perplexed because it will push the stale air from the wet rooms to the dry rooms!

Yes I inquired. It is out of the question to spend such a sum of money just to dehumidify my bathroom and renew the air in the house !!!
for resistance, I saw that. That's why I don't want to buy a ready-made thing. A small vmc connected upside down (the pipe provided for the discharge towards the roof oriented towards the interior of the house) a little heat recovery by attaching an aluminum sheath to my heating pipes and that will be enough. (for the moment these pipes are insulated. I plan to remove the insulation over a certain length, touch my ventilation duct and surround the assembly with insulation.

Finally, my husband finds that I complicate my life. He would like to stay like this. But he is not at all handy ...
I tell myself that if it is just a question of buying a small vmc and a few ducts and a programmable socket, it is tempted!

[Aumicron]

Finally, my husband finds that I complicate my life. He would like to stay like this. But he is not at all handy ...

Bravo nutt, you are right. You must stir your husband. No but...
More seriously, regarding your boiler, you can not move the air inlet of the boiler outside the heated volume?