ᐅ Advantages and Disadvantages of Ventilation and Exhaust Systems

Yes, I keep reading two different opinions everywhere:

1. No, I can just open windows! – From people who don’t know the ventilation systems and have never experienced them.

2. Never again without one! – From those who know ventilation systems or have taken the step to install one.

As you can see, if you haven’t experienced it yourself, you are usually against it… but once you have experienced it, you don’t want to miss it.

As my predecessors said, the noise level strongly depends on the type of system, installation location, air circulation volume, etc. My system is in the utility room, and starting from 200 cubic meters per hour it is barely audible “from far away,” but much quieter… at night the system runs at 50 cubic meters per hour (approximately 30 cubic feet per minute), and you can’t hear it at all… at the “party mode,” meaning full power, you can hear the system at about laptop volume… but full power is rarely used… and if you are having a party, you don’t notice it anyway…

When you open windows, external environmental noise also comes in…

I mentioned this as a disadvantage, but only for completeness… every kitchen exhaust hood is many times louder even at the lowest setting…

kaho674 schrieb:
Okay, so there are advantages then. Although, sorry for saying this, I'm still in favor of just opening the windows. I also sleep with the window open – even in winter.
How loud is the system? Does it constantly hum? Is it as loud as a laptop, for example, or quieter?

I honestly don’t know anyone who doesn’t open windows when the temperature is reasonable.
Opening windows in winter: you invest in a high-quality, future-oriented heating system... energy costs skyrocket... and then you let all that energy escape overnight – which is exactly what a mechanical ventilation system aims to prevent.
Also, as mentioned earlier: modern houses nowadays are completely airtight, like a plastic bag. We produce moisture through showering, cooking, and sweating at night. Combined with heated air, this eventually leads to mold.
Your evening ventilation in living spaces isn’t enough to remove all the moisture. You need several ventilation cycles throughout the day… I once read about 6 to 7 ventilation intervals.
Who can manage that? Exactly: the mechanical ventilation system.

We keep the windows closed whenever possible. In summer, to keep the heat out. And at night, to keep out the millions of flies and mosquitoes (the joys of country life on the Rhine).
In winter, to avoid losing expensive heated air.
The only exception is when the fireplace is on; then I crack a window open... otherwise, it gets too warm.

Our ventilation system always runs on setting 1, 50 cubic meters per hour. Only when guests are over, a lot of baking has been done, or it simply gets too warm do we increase it.

What is actually a myth, at least in my experience, is that the controlled ventilation system warms the other rooms when the fireplace is burning.
I checked in spring once... outside temperature was -5°C (23°F), fireplace running at full power, supply air temperature in the system was 15°C (59°F). But the rooms upstairs were at 18°C (64°F)... so it doesn’t heat the rooms. And if it does, the effect is minimal. What helps more is opening the living room door and using a small fan to blow the warm air out. (Our fireplace is right next to the door.)

Der Da schrieb:

Our ventilation system is always running at level 1, 50 cubic meters per hour. Only when guests are over, a lot of baking has been done, or it simply gets too warm do we increase it.

That seems a bit low to me. You also have around 130-140 square meters (1400-1500 square feet), right? For that, we need 120 cubic meters per hour at level 1. Then, unfortunately, you can also hear the ventilation system.

We can’t get the dry air under control – humidifiers, damp towels – all attempts end up at a maximum of 40 percent humidity. Does anyone have any tips? We have an evaporative humidifier (supposedly designed for 40 square meters (430 square feet)).

Wastl schrieb:
That seems a bit low to me? You also have around 130-140 sqm (1400-1500 sq ft), right? We need about 120 cubic meters (4200 cubic feet) on level 1. Unfortunately, then you can hear the ventilation system as well.
We can’t seem to control the dry air in our house – humidifiers, damp cloths – all attempts only reach a maximum of 40 percent. Does anyone have any tips? We have an evaporative humidifier (supposedly designed for 40 sqm (430 sq ft)).

You might be right. I only checked the manual, but I just noticed that it actually describes more than 3 levels… I guess my 3 levels are somehow configured or calibrated. So, I can’t specify the current airflow. I would need to check the protocol for that.

Regarding humidity… houseplants with large leaves can help… But what exactly is wrong with 40%? That’s actually normal in winter…

ypg schrieb:

Your evening ventilation in your living spaces is not enough to remove the moisture. There need to be more intervals during the day... I once read about 6 to 7 ventilation intervals.

Wow! Is that true? Then all new houses without mechanical ventilation systems would have mold, because who would ventilate 6 to 7 times a day?

What I also don’t understand is that the ventilation system is supposed to remove moisture, but many people here write that the humidity inside the rooms actually rises and that this is even intentional. Another user (see above) says that with mechanical ventilation, the rooms become too dry. So, which is it—does it get drier or more humid? Am I missing something here?